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Inhibition of colony stimulating factor 1 receptor corrects maternal inflammation-induced microglial and synaptic dysfunction and behavioral abnormalities. Mol Psychiatry 2021; 26:1808-1831. [PMID: 32071385 PMCID: PMC7431382 DOI: 10.1038/s41380-020-0671-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 01/21/2020] [Accepted: 01/29/2020] [Indexed: 12/23/2022]
Abstract
Maternal immune activation (MIA) disrupts the central innate immune system during a critical neurodevelopmental period. Microglia are primary innate immune cells in the brain although their direct influence on the MIA phenotype is largely unknown. Here we show that MIA alters microglial gene expression with upregulation of cellular protrusion/neuritogenic pathways, concurrently causing repetitive behavior, social deficits, and synaptic dysfunction to layer V intrinsically bursting pyramidal neurons in the prefrontal cortex of mice. MIA increases plastic dendritic spines of the intrinsically bursting neurons and their interaction with hyper-ramified microglia. Treating MIA offspring by colony stimulating factor 1 receptor inhibitors induces depletion and repopulation of microglia, and corrects protein expression of the newly identified MIA-associated neuritogenic molecules in microglia, which coalesces with correction of MIA-associated synaptic, neurophysiological, and behavioral abnormalities. Our study demonstrates that maternal immune insults perturb microglial phenotypes and influence neuronal functions throughout adulthood, and reveals a potent effect of colony stimulating factor 1 receptor inhibitors on the correction of MIA-associated microglial, synaptic, and neurobehavioral dysfunctions.
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52
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Perisomatic innervation and neurochemical features of giant pyramidal neurons in both hemispheres of the human primary motor cortex. Brain Struct Funct 2020; 226:281-296. [PMID: 33355694 PMCID: PMC7817582 DOI: 10.1007/s00429-020-02182-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 11/24/2020] [Indexed: 12/11/2022]
Abstract
Betz cells-the gigantopyramidal neurons found in high amount in the primary motor cortex-are among of the most characteristic neuronal cells. A part of them contains the calcium-binding protein parvalbumin (PV) in primates. However, less is known about these cells in the human motor cortex despite their important role in different neurological disorders. Therefore, the aim of our study was to investigate the neurochemical features and perisomatic input properties of Betz cells in control human samples with short post-mortem interval. We used different microscopic techniques to investigate the primary motor cortex of both hemispheres. The soma size and density, and expression of PV of the Betz cells were investigated. Furthermore, we used confocal fluorescent and electron microscopy to examine their perisomatic input. The soma size and density showed moderate variability among samples and hemispheres. Post-mortem interval and hemispherical localization did not influence these features. Around 70% of Betz cells expressed PV, but in less intensity than the cortical interneurons. Betz neurons receive dense perisomatic input, which are mostly VIAAT- (vesicular inhibitory amino acid transporter) and PV immunopositive. In the electron microscope, we found PV-immunolabelled terminals with asymmetric-like synaptic structure, too. Terminals with morphologically similar synaptic specialisation were also found among vGluT2- (vesicular glutamate transporter type 2) immunostained terminals contacting Betz cells. Our data suggest that Betz cells' morphological properties showed less variability among subjects and hemispheres than the density of them. Their neurochemical and perisomatic input characteristics support their role in execution of fast and precise movements.
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53
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Crabé R, Aimond F, Gosset P, Scamps F, Raoul C. How Degeneration of Cells Surrounding Motoneurons Contributes to Amyotrophic Lateral Sclerosis. Cells 2020; 9:cells9122550. [PMID: 33260927 PMCID: PMC7760029 DOI: 10.3390/cells9122550] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 11/19/2020] [Accepted: 11/24/2020] [Indexed: 12/13/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurological disorder characterized by the progressive degeneration of upper and lower motoneurons. Despite motoneuron death being recognized as the cardinal event of the disease, the loss of glial cells and interneurons in the brain and spinal cord accompanies and even precedes motoneuron elimination. In this review, we provide striking evidence that the degeneration of astrocytes and oligodendrocytes, in addition to inhibitory and modulatory interneurons, disrupt the functionally coherent environment of motoneurons. We discuss the extent to which the degeneration of glial cells and interneurons also contributes to the decline of the motor system. This pathogenic cellular network therefore represents a novel strategic field of therapeutic investigation.
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Affiliation(s)
- Roxane Crabé
- The Neuroscience Institute of Montpellier, INSERM, UMR1051, University of Montpellier, 34091 Montpellier, France; (R.C.); (F.A.); (P.G.); (F.S.)
| | - Franck Aimond
- The Neuroscience Institute of Montpellier, INSERM, UMR1051, University of Montpellier, 34091 Montpellier, France; (R.C.); (F.A.); (P.G.); (F.S.)
| | - Philippe Gosset
- The Neuroscience Institute of Montpellier, INSERM, UMR1051, University of Montpellier, 34091 Montpellier, France; (R.C.); (F.A.); (P.G.); (F.S.)
| | - Frédérique Scamps
- The Neuroscience Institute of Montpellier, INSERM, UMR1051, University of Montpellier, 34091 Montpellier, France; (R.C.); (F.A.); (P.G.); (F.S.)
| | - Cédric Raoul
- The Neuroscience Institute of Montpellier, INSERM, UMR1051, University of Montpellier, 34091 Montpellier, France; (R.C.); (F.A.); (P.G.); (F.S.)
- Laboratory of Neurobiology, Kazan Federal University, 420008 Kazan, Russia
- Correspondence:
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54
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Quarta E, Cohen EJ, Bravi R, Minciacchi D. Future Portrait of the Athletic Brain: Mechanistic Understanding of Human Sport Performance Via Animal Neurophysiology of Motor Behavior. Front Syst Neurosci 2020; 14:596200. [PMID: 33281568 PMCID: PMC7705174 DOI: 10.3389/fnsys.2020.596200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 10/19/2020] [Indexed: 11/24/2022] Open
Abstract
Sport performances are often showcases of skilled motor control. Efforts to understand the neural processes subserving such movements may teach us about general principles of behavior, similarly to how studies on neurological patients have guided early work in cognitive neuroscience. While investigations on non-human animal models offer valuable information on the neural dynamics of skilled motor control that is still difficult to obtain from humans, sport sciences have paid relatively little attention to these mechanisms. Similarly, knowledge emerging from the study of sport performance could inspire innovative experiments in animal neurophysiology, but the latter has been only partially applied. Here, we advocate that fostering interactions between these two seemingly distant fields, i.e., animal neurophysiology and sport sciences, may lead to mutual benefits. For instance, recording and manipulating the activity from neurons of behaving animals offer a unique viewpoint on the computations for motor control, with potentially untapped relevance for motor skills development in athletes. To stimulate such transdisciplinary dialog, in the present article, we also discuss steps for the reverse translation of sport sciences findings to animal models and the evaluation of comparability between animal models of a given sport and athletes. In the final section of the article, we envision that some approaches developed for animal neurophysiology could translate to sport sciences anytime soon (e.g., advanced tracking methods) or in the future (e.g., novel brain stimulation techniques) and could be used to monitor and manipulate motor skills, with implications for human performance extending well beyond sport.
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Affiliation(s)
| | | | | | - Diego Minciacchi
- Physiological Sciences Section, Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
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55
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Popescu IR, Le KQ, Ducote AL, Li JE, Leland AE, Mostany R. Increased intrinsic excitability and decreased synaptic inhibition in aged somatosensory cortex pyramidal neurons. Neurobiol Aging 2020; 98:88-98. [PMID: 33249377 DOI: 10.1016/j.neurobiolaging.2020.10.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 09/02/2020] [Accepted: 10/08/2020] [Indexed: 10/23/2022]
Abstract
Sensorimotor performance declines during advanced age, partially due to deficits in somatosensory acuity. Cortical receptive field expansion contributes to somatosensory deficits, suggesting increased excitability or decreased inhibition in primary somatosensory cortex (S1) pyramidal neurons. To ascertain changes in excitability and inhibition, we measured both properties in neurons from vibrissal S1 in brain slices from young and aged mice. Because adapting and non-adapting neurons-the principal pyramidal types in layer 5 (L5)-differ in intrinsic properties and inhibitory inputs, we determined age-dependent changes according to neuron type. We found an age-dependent increase in intrinsic excitability in adapting neurons, caused by a decrease in action potential threshold. Surprisingly, in non-adapting neurons we found both an increase in excitability caused by increased input resistance, and a decrease in synaptic inhibition. Spike frequency adaptation, already small in non-adapting neurons, was further reduced by aging, whereas sag, a manifestation of Ih, was increased. Therefore, aging caused both decreased inhibition and increased intrinsic excitability, but these effects were specific to pyramidal neuron type.
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Affiliation(s)
- Ion R Popescu
- Department of Pharmacology, Tulane University School of Medicine, New Orleans, LA, USA.
| | - Kathy Q Le
- Tulane Brain Institute, Tulane University, New Orleans, LA, USA
| | - Alexis L Ducote
- Department of Pharmacology, Tulane University School of Medicine, New Orleans, LA, USA; Tulane Brain Institute, Tulane University, New Orleans, LA, USA
| | - Jennifer E Li
- Tulane Brain Institute, Tulane University, New Orleans, LA, USA
| | | | - Ricardo Mostany
- Department of Pharmacology, Tulane University School of Medicine, New Orleans, LA, USA; Tulane Brain Institute, Tulane University, New Orleans, LA, USA
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56
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Petrus E, Dembling S, Usdin T, Isaac JTR, Koretsky AP. Circuit-Specific Plasticity of Callosal Inputs Underlies Cortical Takeover. J Neurosci 2020; 40:7714-7723. [PMID: 32913109 PMCID: PMC7531555 DOI: 10.1523/jneurosci.1056-20.2020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 06/13/2020] [Accepted: 08/21/2020] [Indexed: 02/06/2023] Open
Abstract
Injury induces synaptic, circuit, and systems reorganization. After unilateral amputation or stroke, this functional loss disrupts the interhemispheric interaction between intact and deprived somatomotor cortices to recruit deprived cortex in response to intact limb stimulation. This recruitment has been implicated in enhanced intact sensory function. In other patients, maladaptive consequences such as phantom limb pain can occur. We used unilateral whisker denervation in male and female mice to detect circuitry alterations underlying interhemispheric cortical reorganization. Enhanced synaptic strength from the intact cortex via the corpus callosum (CC) onto deep neurons in deprived primary somatosensory barrel cortex (S1BC) has previously been detected. It was hypothesized that specificity in this plasticity may depend on to which area these neurons projected. Increased connectivity to somatomotor areas such as contralateral S1BC, primary motor cortex (M1) and secondary somatosensory cortex (S2) may underlie beneficial adaptations, while increased connectivity to pain areas like anterior cingulate cortex (ACC) might underlie maladaptive pain phenotypes. Neurons from the deprived S1BC that project to intact S1BC were hyperexcitable, had stronger responses and reduced inhibitory input to CC stimulation. M1-projecting neurons also showed increases in excitability and CC input strength that was offset with enhanced inhibition. S2 and ACC-projecting neurons showed no changes in excitability or CC input. These results demonstrate that subgroups of output neurons undergo dramatic and specific plasticity after peripheral injury. The changes in S1BC-projecting neurons likely underlie enhanced reciprocal connectivity of S1BC after unilateral deprivation consistent with the model that interhemispheric takeover supports intact whisker processing.SIGNIFICANCE STATEMENT Amputation, peripheral injury, and stroke patients experience widespread alterations in neural activity after sensory loss. A hallmark of this reorganization is the recruitment of deprived cortical space which likely aids processing and thus enhances performance on intact sensory systems. Conversely, this recruitment of deprived cortical space has been hypothesized to underlie phenotypes like phantom limb pain and hinder recovery. A mouse model of unilateral denervation detected remarkable specificity in alterations in the somatomotor circuit. These changes underlie increased reciprocal connectivity between intact and deprived cortical hemispheres. This increased connectivity may help explain the enhanced intact sensory processing detected in humans.
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Affiliation(s)
- Emily Petrus
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892
| | - Sarah Dembling
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892
| | - Ted Usdin
- Systems Neuroscience Imaging Resource, National Institute of Mental Health, Bethesda, Maryland 20892
| | - John T R Isaac
- Janssen Neuroscience, J&J Innovations, London W1G 0BG, United Kingdom
| | - Alan P Koretsky
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892
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57
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Anastasiades PG, Boada C, Carter AG. Cell-Type-Specific D1 Dopamine Receptor Modulation of Projection Neurons and Interneurons in the Prefrontal Cortex. Cereb Cortex 2020; 29:3224-3242. [PMID: 30566584 DOI: 10.1093/cercor/bhy299] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 11/01/2018] [Accepted: 11/07/2018] [Indexed: 11/14/2022] Open
Abstract
Dopamine modulation in the prefrontal cortex (PFC) mediates diverse effects on neuronal physiology and function, but the expression of dopamine receptors at subpopulations of projection neurons and interneurons remains unresolved. Here, we examine D1 receptor expression and modulation at specific cell types and layers in the mouse prelimbic PFC. We first show that D1 receptors are enriched in pyramidal cells in both layers 5 and 6, and that these cells project to intratelencephalic targets including contralateral cortex, striatum, and claustrum rather than to extratelencephalic structures. We then find that D1 receptors are also present in interneurons and enriched in superficial layer VIP-positive (VIP+) interneurons that coexpresses calretinin but absent from parvalbumin-positive (PV+) and somatostatin-positive (SOM+) interneurons. Finally, we determine that D1 receptors strongly and selectively enhance action potential firing in only a subset of these corticocortical neurons and VIP+ interneurons. Our findings define several novel subpopulations of D1+ neurons, highlighting how modulation via D1 receptors can influence both excitatory and disinhibitory microcircuits in the PFC.
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Affiliation(s)
- Paul G Anastasiades
- Center for Neural Science, New York University, 4 Washington Place, New York, NY, USA
| | - Christina Boada
- Center for Neural Science, New York University, 4 Washington Place, New York, NY, USA
| | - Adam G Carter
- Center for Neural Science, New York University, 4 Washington Place, New York, NY, USA
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58
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Streffing-Hellhake P, Luft A, Hosp J. Motor Learning Induces Profound but Delayed Dendritic Plasticity in M1 Layer II/III Pyramidal Neurons. Neuroscience 2020; 442:17-28. [DOI: 10.1016/j.neuroscience.2020.06.039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2020] [Revised: 06/25/2020] [Accepted: 06/26/2020] [Indexed: 10/23/2022]
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59
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Wiegel P, Leukel C. Training of a discrete motor skill in humans is accompanied by increased excitability of the fastest corticospinal connections at movement onset. J Physiol 2020; 598:3485-3500. [DOI: 10.1113/jp279879] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 05/21/2020] [Indexed: 11/08/2022] Open
Affiliation(s)
- Patrick Wiegel
- Department of Sport Science University of Freiburg Freiburg 79117 Germany
- Bernstein Center Freiburg University of Freiburg Freiburg 79104 Germany
| | - Christian Leukel
- Department of Sport Science University of Freiburg Freiburg 79117 Germany
- Bernstein Center Freiburg University of Freiburg Freiburg 79104 Germany
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60
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Corticospinal Pathways and Interactions Underpinning Dexterous Forelimb Movement of the Rodent. Neuroscience 2020; 450:184-191. [PMID: 32512136 DOI: 10.1016/j.neuroscience.2020.05.050] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 05/26/2020] [Accepted: 05/27/2020] [Indexed: 12/17/2022]
Abstract
In 2013, Thomas Jessell published a paper with Andrew Miri and Eiman Azim that took on the task of examining corticospinal neuron function during movement (Miri et al., 2013). They took the view that a combination of approaches would be able to shed light on corticospinal function, and that this function must be considered in the context of corticospinal connectivity with spinal circuits. In this review, we will highlight recent developments in this area, along with new information regarding inputs and cross-connectivity of the corticospinal circuit with other circuits across the rodent central nervous system. The genetic and viral manipulations available in these animals have led to new insights into descending circuit interaction and function. As species differences exist in the circuitry profile that contributes to dexterous forelimb movements (Lemon, 2008; Yoshida and Isa, 2018), highlighting important advances in one model could help to compare and contrast with what is known about other models. We will focus on the circuitry underpinning dexterous forelimb movements, including some recent developments from systems besides the corticospinal tract, to build a more holistic understanding of sensorimotor circuits and their control of voluntary movement. The rodent corticospinal system is thus a central point of reference in this review, but not the only focus.
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61
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Delevich K, Okada NJ, Rahane A, Zhang Z, Hall CD, Wilbrecht L. Sex and Pubertal Status Influence Dendritic Spine Density on Frontal Corticostriatal Projection Neurons in Mice. Cereb Cortex 2020; 30:3543-3557. [PMID: 32037445 DOI: 10.1093/cercor/bhz325] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
In humans, nonhuman primates, and rodents, the frontal cortices exhibit grey matter thinning and dendritic spine pruning that extends into adolescence. This maturation is believed to support higher cognition but may also confer psychiatric vulnerability during adolescence. Currently, little is known about how specific cell types in the frontal cortex mature or whether puberty plays a role in the maturation of some cell types but not others. Here, we used mice to characterize the spatial topography and adolescent development of cross-corticostriatal (cSTR) neurons that project through the corpus collosum to the dorsomedial striatum. We found that apical spine density on cSTR neurons in the medial prefrontal cortex decreased significantly between late juvenile (P29) and young adult time points (P60), with females exhibiting higher spine density than males at both ages. Adult males castrated prior to puberty onset had higher spine density compared to sham controls. Adult females ovariectomized before puberty onset showed greater variance in spine density measures on cSTR cells compared to controls, but their mean spine density did not significantly differ from sham controls. Our findings reveal that these cSTR neurons, a subtype of the broader class of intratelencephalic-type neurons, exhibit significant sex differences and suggest that spine pruning on cSTR neurons is regulated by puberty in male mice.
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Affiliation(s)
- Kristen Delevich
- Department of Psychology, University of California, Berkeley, CA 94720, USA and.,Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720, USA
| | - Nana J Okada
- Department of Psychology, University of California, Berkeley, CA 94720, USA and.,Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720, USA
| | - Ameet Rahane
- Department of Psychology, University of California, Berkeley, CA 94720, USA and.,Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720, USA
| | - Zicheng Zhang
- Department of Psychology, University of California, Berkeley, CA 94720, USA and.,Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720, USA
| | - Christopher D Hall
- Department of Psychology, University of California, Berkeley, CA 94720, USA and.,Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720, USA
| | - Linda Wilbrecht
- Department of Psychology, University of California, Berkeley, CA 94720, USA and.,Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720, USA
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62
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Lees RM, Johnson JD, Ashby MC. Presynaptic Boutons That Contain Mitochondria Are More Stable. Front Synaptic Neurosci 2020; 11:37. [PMID: 31998110 PMCID: PMC6966497 DOI: 10.3389/fnsyn.2019.00037] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 12/18/2019] [Indexed: 01/04/2023] Open
Abstract
The addition and removal of presynaptic terminals reconfigures neuronal circuits of the mammalian neocortex, but little is known about how this presynaptic structural plasticity is controlled. Since mitochondria can regulate presynaptic function, we investigated whether the presence of axonal mitochondria relates to the structural plasticity of presynaptic boutons in mouse neocortex. We found that the overall density of axonal mitochondria did not appear to influence the loss and gain of boutons. However, positioning of mitochondria at individual presynaptic sites did relate to increased stability of those boutons. In line with this, synaptic localization of mitochondria increased as boutons aged and showed differing patterns of localization at en passant and terminaux boutons. These results suggest that mitochondria accumulate locally at boutons over time to increase bouton stability.
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Affiliation(s)
| | | | - Michael C. Ashby
- School of Physiology, Pharmacology, and Neuroscience, Faculty of Biomedical Sciences, University of Bristol, Bristol, United Kingdom
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63
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Li N, Chen S, Guo ZV, Chen H, Huo Y, Inagaki HK, Chen G, Davis C, Hansel D, Guo C, Svoboda K. Spatiotemporal constraints on optogenetic inactivation in cortical circuits. eLife 2019; 8:e48622. [PMID: 31736463 PMCID: PMC6892606 DOI: 10.7554/elife.48622] [Citation(s) in RCA: 97] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 11/16/2019] [Indexed: 12/21/2022] Open
Abstract
Optogenetics allows manipulations of genetically and spatially defined neuronal populations with excellent temporal control. However, neurons are coupled with other neurons over multiple length scales, and the effects of localized manipulations thus spread beyond the targeted neurons. We benchmarked several optogenetic methods to inactivate small regions of neocortex. Optogenetic excitation of GABAergic neurons produced more effective inactivation than light-gated ion pumps. Transgenic mice expressing the light-dependent chloride channel GtACR1 produced the most potent inactivation. Generally, inactivation spread substantially beyond the photostimulation light, caused by strong coupling between cortical neurons. Over some range of light intensity, optogenetic excitation of inhibitory neurons reduced activity in these neurons, together with pyramidal neurons, a signature of inhibition-stabilized neural networks ('paradoxical effect'). The offset of optogenetic inactivation was followed by rebound excitation in a light dose-dependent manner, limiting temporal resolution. Our data offer guidance for the design of in vivo optogenetics experiments.
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Affiliation(s)
- Nuo Li
- Department of NeuroscienceBaylor College of MedicineHoustonUnited States
- Janelia Research CampusAshburnUnited States
| | - Susu Chen
- Janelia Research CampusAshburnUnited States
| | - Zengcai V Guo
- Janelia Research CampusAshburnUnited States
- School of MedicineTsinghua UniversityBeijingChina
| | - Han Chen
- School of MedicineTsinghua UniversityBeijingChina
| | - Yan Huo
- School of MedicineTsinghua UniversityBeijingChina
| | | | - Guang Chen
- Department of NeuroscienceBaylor College of MedicineHoustonUnited States
| | - Courtney Davis
- Department of NeuroscienceBaylor College of MedicineHoustonUnited States
- Janelia Research CampusAshburnUnited States
| | - David Hansel
- Center of Neurophysics, Physiology and Pathologies, CNRS-UMR8119ParisFrance
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64
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Gjorgjieva J, Meister M, Sompolinsky H. Functional diversity among sensory neurons from efficient coding principles. PLoS Comput Biol 2019; 15:e1007476. [PMID: 31725714 PMCID: PMC6890262 DOI: 10.1371/journal.pcbi.1007476] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 12/03/2019] [Accepted: 10/10/2019] [Indexed: 01/10/2023] Open
Abstract
In many sensory systems the neural signal is coded by the coordinated response of heterogeneous populations of neurons. What computational benefit does this diversity confer on information processing? We derive an efficient coding framework assuming that neurons have evolved to communicate signals optimally given natural stimulus statistics and metabolic constraints. Incorporating nonlinearities and realistic noise, we study optimal population coding of the same sensory variable using two measures: maximizing the mutual information between stimuli and responses, and minimizing the error incurred by the optimal linear decoder of responses. Our theory is applied to a commonly observed splitting of sensory neurons into ON and OFF that signal stimulus increases or decreases, and to populations of monotonically increasing responses of the same type, ON. Depending on the optimality measure, we make different predictions about how to optimally split a population into ON and OFF, and how to allocate the firing thresholds of individual neurons given realistic stimulus distributions and noise, which accord with certain biases observed experimentally.
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Affiliation(s)
| | - Markus Meister
- Division of Biology, California Institute of Technology, Pasadena, California, United States of America
| | - Haim Sompolinsky
- Center for Brain Science, Harvard University, Cambridge, Massachusetts, United States of America
- The Edmond and Lily Safra Center for Brain Sciences, Hebrew University, Jerusalem, Israel
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65
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Mercer Lindsay N, Knutsen PM, Lozada AF, Gibbs D, Karten HJ, Kleinfeld D. Orofacial Movements Involve Parallel Corticobulbar Projections from Motor Cortex to Trigeminal Premotor Nuclei. Neuron 2019; 104:765-780.e3. [PMID: 31587918 DOI: 10.1016/j.neuron.2019.08.032] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 07/07/2019] [Accepted: 08/19/2019] [Indexed: 01/21/2023]
Abstract
How do neurons in orofacial motor cortex (MCtx) orchestrate behaviors? We show that focal activation of MCtx corticobulbar neurons evokes behaviorally relevant concurrent movements of the forelimb, jaw, nose, and vibrissae. The projections from different locations in MCtx form gradients of boutons across premotor nuclei spinal trigeminal pars oralis (SpVO) and interpolaris rostralis (SpVIr). Furthermore, retrograde viral tracing from muscles that control orofacial actions shows that these premotor nuclei segregate their outputs. In the most dramatic case, both SpVO and SpVIr are premotor to forelimb and vibrissa muscles, while only SpVO is premotor to jaw muscles. Functional confirmation of the superimposed control by MCtx was obtained through selective optogenetic activation of corticobulbar neurons on the basis of their preferential projections to SpVO versus SpVIr. We conclude that neighboring projection neurons in orofacial MCtx form parallel pathways to distinct pools of trigeminal premotor neurons that coordinate motor actions into a behavior.
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Affiliation(s)
- Nicole Mercer Lindsay
- Section of Neurobiology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Per M Knutsen
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA
| | - Adrian F Lozada
- Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA
| | - Daniel Gibbs
- Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Harvey J Karten
- Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - David Kleinfeld
- Section of Neurobiology, University of California, San Diego, La Jolla, CA 92093, USA; Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA.
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66
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Rasmussen R, Nicholas E, Petersen NC, Dietz AG, Xu Q, Sun Q, Nedergaard M. Cortex-wide Changes in Extracellular Potassium Ions Parallel Brain State Transitions in Awake Behaving Mice. Cell Rep 2019; 28:1182-1194.e4. [PMID: 31365863 PMCID: PMC6790006 DOI: 10.1016/j.celrep.2019.06.082] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 06/01/2019] [Accepted: 06/24/2019] [Indexed: 12/21/2022] Open
Abstract
Brain state fluctuations modulate sensory processing, but the factors governing state-dependent neural activity remain unclear. Here, we tracked the dynamics of cortical extracellular K+ concentrations ([K+]o) during awake state transitions and manipulated [K+]o in slices, during visual processing, and during skilled motor execution. When mice transitioned from quiescence to locomotion, [K+]o increased by 0.6-1.0 mM in all cortical areas analyzed, and this preceded locomotion by 1 s. Emulating the state-dependent [K+]o increase in cortical slices caused neuronal depolarization and enhanced input-output transformation. In vivo, locomotion increased the gain of visually evoked responses in layer 2/3 of visual cortex; this effect was recreated by imposing a [K+]o increase. Elevating [K+]o in the motor cortex increased movement-induced neuronal spiking in layer 5 and improved motor performance. Thus, [K+]o increases in a cortex-wide state-dependent manner, and this [K+]o increase affects both sensory and motor processing through the dynamic modulation of neural activity.
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Affiliation(s)
- Rune Rasmussen
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen N, Denmark.
| | - Eric Nicholas
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Nicolas Caesar Petersen
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Andrea Grostøl Dietz
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Qiwu Xu
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Qian Sun
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Maiken Nedergaard
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, NY 14642, USA; Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen N, Denmark.
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67
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Saba L, Viscomi MT, Martini A, Caioli S, Mercuri NB, Guatteo E, Zona C. Modified age-dependent expression of NaV1.6 in an ALS model correlates with motor cortex excitability alterations. Neurobiol Dis 2019; 130:104532. [PMID: 31302244 DOI: 10.1016/j.nbd.2019.104532] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 06/28/2019] [Accepted: 07/10/2019] [Indexed: 12/13/2022] Open
Abstract
Cortical hyperexcitability is an early and intrinsic feature of Amyotrophic Lateral Sclerosis (ALS), but the mechanisms underlying this critical neuronal dysfunction are poorly understood. Recently, we have demonstrated that layer V pyramidal neurons (PNs) in the primary motor cortex (M1) of one-month old (P30) G93A ALS mice display an early hyperexcitability status compared to Control mice. In order to investigate the time-dependent evolution of the cortical excitability in the G93A ALS model, here we have performed an electrophysiological and immunohistochemical study at three different mouse ages. M1 PNs from 14-days old (P14) G93A mice have shown no excitability alterations, while M1 PNs from 3-months old (P90) G93A mice have shown a hypoexcitability status, compared to Control mice. These age-dependent cortical excitability dysfunctions correlate with a similar time-dependent trend of the persistent sodium current (INaP) amplitude alterations, suggesting that INaP may play a crucial role in the G93A cortical excitability aberrations. Specifically, immunohistochemistry experiments have indicated that the expression level of the NaV1.6 channel, one of the voltage-gated Na+ channels mainly distributed within the central nervous system, varies in G93A primary motor cortex during disease progression, according to the excitability and INaP alterations, but not in other cortical areas. Microfluorometry experiments, combined with electrophysiological recordings, have verified that P30 G93A PNs hyperexcitability is associated to a greater accumulation of intracellular calcium ([Ca2+]i) compared to Control PNs, and that this difference is still present when G93A and Control PNs fire action potentials at the same frequency. These results suggest that [Ca2+]i de-regulation in G93A PNs may contribute to neuronal demise and that the NaV1.6 channels could be a potential therapeutic target to ameliorate ALS disease progression.
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Affiliation(s)
- Luana Saba
- Department of Systems Medicine, University of Rome "Tor Vergata" via Montpellier 1, Rome 00133, Italy
| | - Maria Teresa Viscomi
- Università Cattolica del Sacro Cuore, Istituto di Istologia ed Embriologia, Fondazione Policlinico Universitario A. Gemelli, Largo F. Vito 1, Rome 00168, Italy
| | - Alessandro Martini
- IRCCS Fondazione Santa Lucia, via del Fosso di Fiorano 64, Rome 00143, Italy
| | - Silvia Caioli
- IRCCS Fondazione Santa Lucia, via del Fosso di Fiorano 64, Rome 00143, Italy
| | - Nicola Biagio Mercuri
- Department of Systems Medicine, University of Rome "Tor Vergata" via Montpellier 1, Rome 00133, Italy; IRCCS Fondazione Santa Lucia, via del Fosso di Fiorano 64, Rome 00143, Italy
| | - Ezia Guatteo
- IRCCS Fondazione Santa Lucia, via del Fosso di Fiorano 64, Rome 00143, Italy; Department of Motor Science and Wellness, University of Naples 'Parthenope', Via Medina 40, Naples 80133, Italy
| | - Cristina Zona
- Department of Systems Medicine, University of Rome "Tor Vergata" via Montpellier 1, Rome 00133, Italy; IRCCS Fondazione Santa Lucia, via del Fosso di Fiorano 64, Rome 00143, Italy.
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68
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Khodashenas M, Baghdadi G, Towhidkhah F. A modified Hodgkin-Huxley model to show the effect of motor cortex stimulation on the trigeminal neuralgia network. JOURNAL OF MATHEMATICAL NEUROSCIENCE 2019; 9:4. [PMID: 31152270 PMCID: PMC6544710 DOI: 10.1186/s13408-019-0072-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Accepted: 05/21/2019] [Indexed: 06/09/2023]
Abstract
BACKGROUND Trigeminal neuralgia (TN) is a severe neuropathic pain, which has an electric shock-like characteristic. There are some common treatments for this pain such as medicine, microvascular decompression or radio frequency. In this regard, transcranial direct current stimulation (tDCS) is another therapeutic method to reduce pain, which has been recently attracting the therapists' attention. The positive effect of tDCS on TN was shown in many previous studies. However, the mechanism of the tDCS effect has remained unclear. OBJECTIVE This study aims to model the neuronal behavior of the main known regions of the brain participating in TN pathways to study the effect of transcranial direct current stimulation. METHOD The proposed model consists of several blocks: (1) trigeminal nerve, (2) trigeminal ganglion, (3) PAG (periaqueductal gray in the brainstem), (4) thalamus, (5) motor cortex (M1) and (6) somatosensory cortex (S1). Each of these components is represented by a modified Hodgkin-Huxley (HH) model. The modification of the HH model was done based on some neurological facts of pain sodium channels. The input of the model involves any stimuli to the 'trigeminal nerve,' which cause the pain, and the output is the activity of the somatosensory cortex. An external current, which is considered as an electrical current, was applied to the motor cortex block of the model. RESULT The results showed that by decreasing the conductivity of the slow sodium channels (pain channels) and applying tDCS over the M1, the activity of the somatosensory cortex would be reduced. This reduction can cause pain relief. CONCLUSION The proposed model provided some possible suggestions about the relationship between the effects of tDCS and associated components in TN, and also the relationship between the pain measurement index, somatosensory cortex activity, and the strength of tDCS.
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Affiliation(s)
| | - Golnaz Baghdadi
- Department of Biomedical Engineering, Amirkabir University of Technology, Tehran, Iran
| | - Farzad Towhidkhah
- Department of Biomedical Engineering, Amirkabir University of Technology, Tehran, Iran
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69
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Lee CR, Yonk AJ, Wiskerke J, Paradiso KG, Tepper JM, Margolis DJ. Opposing Influence of Sensory and Motor Cortical Input on Striatal Circuitry and Choice Behavior. Curr Biol 2019; 29:1313-1323.e5. [PMID: 30982651 DOI: 10.1016/j.cub.2019.03.028] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Revised: 02/04/2019] [Accepted: 03/14/2019] [Indexed: 12/21/2022]
Abstract
The striatum is the main input nucleus of the basal ganglia and is a key site of sensorimotor integration. While the striatum receives extensive excitatory afferents from the cerebral cortex, the influence of different cortical areas on striatal circuitry and behavior is unknown. Here, we find that corticostriatal inputs from whisker-related primary somatosensory (S1) and motor (M1) cortex differentially innervate projection neurons and interneurons in the dorsal striatum and exert opposing effects on sensory-guided behavior. Optogenetic stimulation of S1-corticostriatal afferents in ex vivo recordings produced larger postsynaptic potentials in striatal parvalbumin (PV)-expressing interneurons than D1- or D2-expressing spiny projection neurons (SPNs), an effect not observed for M1-corticostriatal afferents. Critically, in vivo optogenetic stimulation of S1-corticostriatal afferents produced task-specific behavioral inhibition, which was bidirectionally modulated by striatal PV interneurons. Optogenetic stimulation of M1 afferents produced the opposite behavioral effect. Thus, our results suggest opposing roles for sensory and motor cortex in behavioral choice via distinct influences on striatal circuitry.
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Affiliation(s)
- Christian R Lee
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, 604 Allison Road, Piscataway, NJ 08854, USA
| | - Alex J Yonk
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, 604 Allison Road, Piscataway, NJ 08854, USA
| | - Joost Wiskerke
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, 604 Allison Road, Piscataway, NJ 08854, USA
| | - Kenneth G Paradiso
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, 604 Allison Road, Piscataway, NJ 08854, USA
| | - James M Tepper
- Center for Molecular and Behavioral Neuroscience, Rutgers, The State University of New Jersey, 197 University Avenue, Newark, NJ 07102, USA
| | - David J Margolis
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, 604 Allison Road, Piscataway, NJ 08854, USA.
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70
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Buskila Y, Kékesi O, Bellot-Saez A, Seah W, Berg T, Trpceski M, Yerbury JJ, Ooi L. Dynamic interplay between H-current and M-current controls motoneuron hyperexcitability in amyotrophic lateral sclerosis. Cell Death Dis 2019; 10:310. [PMID: 30952836 PMCID: PMC6450866 DOI: 10.1038/s41419-019-1538-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 03/13/2019] [Accepted: 03/19/2019] [Indexed: 12/13/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a type of motor neuron disease (MND) in which humans lose motor functions due to progressive loss of motoneurons in the cortex, brainstem, and spinal cord. In patients and in animal models of MND it has been observed that there is a change in the properties of motoneurons, termed neuronal hyperexcitability, which is an exaggerated response of the neurons to a stimulus. Previous studies suggested neuronal excitability is one of the leading causes for neuronal loss, however the factors that instigate excitability in neurons over the course of disease onset and progression are not well understood, as these studies have looked mainly at embryonic or early postnatal stages (pre-symptomatic). As hyperexcitability is not a static phenomenon, the aim of this study was to assess the overall excitability of upper motoneurons during disease progression, specifically focusing on their oscillatory behavior and capabilities to fire repetitively. Our results suggest that increases in the intrinsic excitability of motoneurons are a global phenomenon of aging, however the cellular mechanisms that underlie this hyperexcitability are distinct in SOD1G93A ALS mice compared with wild-type controls. The ionic mechanism driving increased excitability involves alterations of the expression levels of HCN and KCNQ channel genes leading to a complex dynamic of H-current and M-current activation. Moreover, we show a negative correlation between the disease onset and disease progression, which correlates with a decrease in the expression level of HCN and KCNQ channels. These findings provide a potential explanation for the increased vulnerability of motoneurons to ALS with aging.
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Affiliation(s)
- Yossi Buskila
- Biomedical Engineering and Neuroscience research group, The MARCS Institute, Western Sydney University, Penrith, NSW, 2751, Australia. .,School of Medicine, Western Sydney University, Campbelltown, NSW, 2560, Australia.
| | - Orsolya Kékesi
- Biomedical Engineering and Neuroscience research group, The MARCS Institute, Western Sydney University, Penrith, NSW, 2751, Australia.,School of Medicine, Western Sydney University, Campbelltown, NSW, 2560, Australia.,School of Chemistry and Molecular Bioscience, University of Wollongong, Northfields Avenue, Wollongong, NSW, 2522, Australia.,Illawarra Health and Medical Research Institute, Northfields Avenue, Wollongong, NSW, 2522, Australia
| | - Alba Bellot-Saez
- Biomedical Engineering and Neuroscience research group, The MARCS Institute, Western Sydney University, Penrith, NSW, 2751, Australia.,School of Medicine, Western Sydney University, Campbelltown, NSW, 2560, Australia
| | - Winston Seah
- Biomedical Engineering and Neuroscience research group, The MARCS Institute, Western Sydney University, Penrith, NSW, 2751, Australia.,School of Medicine, Western Sydney University, Campbelltown, NSW, 2560, Australia.,School of Chemistry and Molecular Bioscience, University of Wollongong, Northfields Avenue, Wollongong, NSW, 2522, Australia.,Illawarra Health and Medical Research Institute, Northfields Avenue, Wollongong, NSW, 2522, Australia
| | - Tracey Berg
- School of Chemistry and Molecular Bioscience, University of Wollongong, Northfields Avenue, Wollongong, NSW, 2522, Australia.,Illawarra Health and Medical Research Institute, Northfields Avenue, Wollongong, NSW, 2522, Australia
| | - Michael Trpceski
- School of Chemistry and Molecular Bioscience, University of Wollongong, Northfields Avenue, Wollongong, NSW, 2522, Australia.,Illawarra Health and Medical Research Institute, Northfields Avenue, Wollongong, NSW, 2522, Australia
| | - Justin J Yerbury
- School of Chemistry and Molecular Bioscience, University of Wollongong, Northfields Avenue, Wollongong, NSW, 2522, Australia.,Illawarra Health and Medical Research Institute, Northfields Avenue, Wollongong, NSW, 2522, Australia
| | - Lezanne Ooi
- School of Chemistry and Molecular Bioscience, University of Wollongong, Northfields Avenue, Wollongong, NSW, 2522, Australia. .,Illawarra Health and Medical Research Institute, Northfields Avenue, Wollongong, NSW, 2522, Australia.
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71
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Henderson NT, Le Marchand SJ, Hruska M, Hippenmeyer S, Luo L, Dalva MB. Ephrin-B3 controls excitatory synapse density through cell-cell competition for EphBs. eLife 2019; 8:e41563. [PMID: 30789343 PMCID: PMC6384025 DOI: 10.7554/elife.41563] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 01/31/2019] [Indexed: 11/13/2022] Open
Abstract
Cortical networks are characterized by sparse connectivity, with synapses found at only a subset of axo-dendritic contacts. Yet within these networks, neurons can exhibit high connection probabilities, suggesting that cell-intrinsic factors, not proximity, determine connectivity. Here, we identify ephrin-B3 (eB3) as a factor that determines synapse density by mediating a cell-cell competition that requires ephrin-B-EphB signaling. In a microisland culture system designed to isolate cell-cell competition, we find that eB3 determines winning and losing neurons in a contest for synapses. In a Mosaic Analysis with Double Markers (MADM) genetic mouse model system in vivo the relative levels of eB3 control spine density in layer 5 and 6 neurons. MADM cortical neurons in vitro reveal that eB3 controls synapse density independently of action potential-driven activity. Our findings illustrate a new class of competitive mechanism mediated by trans-synaptic organizing proteins which control the number of synapses neurons receive relative to neighboring neurons.
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Affiliation(s)
- Nathan T Henderson
- Department of Neuroscience, The Vickie and Jack Farber Institute for Neuroscience, Thomas Jefferson University, Philadelphia, United States
- Department of Neuroscience, University of Pennsylvania, Philadelphia, United States
| | | | - Martin Hruska
- Department of Neuroscience, The Vickie and Jack Farber Institute for Neuroscience, Thomas Jefferson University, Philadelphia, United States
| | - Simon Hippenmeyer
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Liqun Luo
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, United States
| | - Matthew B Dalva
- Department of Neuroscience, The Vickie and Jack Farber Institute for Neuroscience, Thomas Jefferson University, Philadelphia, United States
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72
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Beul SF, Hilgetag CC. Neuron density fundamentally relates to architecture and connectivity of the primate cerebral cortex. Neuroimage 2019; 189:777-792. [PMID: 30677500 DOI: 10.1016/j.neuroimage.2019.01.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 01/05/2019] [Indexed: 12/16/2022] Open
Abstract
Studies of structural brain connectivity have revealed many intriguing features of complex cortical networks. To advance integrative theories of cortical organization, an understanding is required of how connectivity interrelates with other aspects of brain structure. Recent studies have suggested that interareal connectivity may be related to a variety of macroscopic as well as microscopic architectonic features of cortical areas. However, it is unclear how these features are inter-dependent and which of them most strongly and fundamentally relate to structural corticocortical connectivity. Here, we systematically investigated the relation of a range of microscopic and macroscopic architectonic features of cortical organization, namely layer III pyramidal cell soma cross section, dendritic synapse count, dendritic synapse density and dendritic tree size as well as area neuron density, to multiple properties of cortical connectivity, using a comprehensive, up-to-date structural connectome of the primate brain. Importantly, relationships were investigated by multi-variate analyses to account for the interrelations of features. Of all considered factors, the classical architectonic parameter of neuron density most strongly and consistently related to essential features of cortical connectivity (existence and laminar patterns of projections, area degree), and in conjoint analyses largely abolished effects of cellular morphological features. These results confirm neuron density as a central architectonic indicator of the primate cerebral cortex that is closely related to essential aspects of brain connectivity and is also highly indicative of further features of the architectonic organization of cortical areas, such as the considered cellular morphological measures. Our findings integrate several aspects of cortical micro- and macroscopic organization, with implications for cortical development and function.
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Affiliation(s)
- Sarah F Beul
- Institute of Computational Neuroscience, University Medical Center Hamburg-Eppendorf, 20246, Hamburg, Germany
| | - Claus C Hilgetag
- Institute of Computational Neuroscience, University Medical Center Hamburg-Eppendorf, 20246, Hamburg, Germany; Department of Health Sciences, Boston University, 02215, Boston, MA, USA.
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73
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Clare AJ, Day RC, Empson RM, Hughes SM. Transcriptome Profiling of Layer 5 Intratelencephalic Projection Neurons From the Mature Mouse Motor Cortex. Front Mol Neurosci 2018; 11:410. [PMID: 30483051 PMCID: PMC6240696 DOI: 10.3389/fnmol.2018.00410] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 10/22/2018] [Indexed: 11/17/2022] Open
Abstract
The mature cortex contains hugely diverse populations of pyramidal projection neurons (PNs), critical to normal forebrain circuits. In order to understand the healthy cortex, it is essential to characterize this neuronal complexity. We recently demonstrated different identities for Fezf2-positive (Fezf2+ve) and Fezf2-negative (Fezf2−ve) intratelencephalic-PNs (IT-PNs) from layer 5 of the motor cortex (M1). Comparatively, each IT-PN type has a distinct electrophysiological phenotype and the Fezf2+ve IT-PNs display a unique apical dendritic tuft. Here, we aimed to expand our understanding of the molecular underpinnings defining these unique IT-PN types. Using a validated Fezf2-GFP reporter mouse, retrograde labeling techniques and fluorescence activated cell sorting (FACS), combined with a novel approach for low-input RNA-sequencing, we isolated mature Fezf2+ve and Fezf2−ve IT-PNs for transcriptome profiling. Through the comparison of Fezf2+ve and Fezf2−ve IT-PN gene expression profiles, we identified significant enrichment of 81 genes in the Fezf2+ve IT-PNs and 119 genes in the Fezf2−ve IT-PNs. Term enrichment analysis of these enriched genes demonstrated significant overrepresentation of the calcium-binding EF-hand domain in Fezf2+ve IT-PNs, suggesting a greater importance for calcium handling in these neurons. Of the Fezf2−ve IT-PN enriched genes an unexpected and unique enrichment of genes, previously associated with microglia were identified. Our dataset identifies the molecular profiles of two unique IT-PN types in the mature M1, providing important targets to investigate for their maintenance in the healthy mature brain.
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Affiliation(s)
- Alison J Clare
- Department of Biochemistry, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.,Brain Health Research Centre, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.,Genetics Otago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Robert C Day
- Department of Biochemistry, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.,Genetics Otago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Ruth M Empson
- Brain Health Research Centre, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.,Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Stephanie M Hughes
- Department of Biochemistry, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.,Brain Health Research Centre, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand.,Genetics Otago, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
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74
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Bedell HW, Song S, Li X, Molinich E, Lin S, Stiller A, Danda V, Ecker M, Shoffstall AJ, Voit WE, Pancrazio JJ, Capadona JR. Understanding the Effects of Both CD14-Mediated Innate Immunity and Device/Tissue Mechanical Mismatch in the Neuroinflammatory Response to Intracortical Microelectrodes. Front Neurosci 2018; 12:772. [PMID: 30429766 PMCID: PMC6220032 DOI: 10.3389/fnins.2018.00772] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 10/04/2018] [Indexed: 01/02/2023] Open
Abstract
Intracortical microelectrodes record neuronal activity of individual neurons within the brain, which can be used to bridge communication between the biological system and computer hardware for both research and rehabilitation purposes. However, long-term consistent neural recordings are difficult to achieve, in large part due to the neuroinflammatory tissue response to the microelectrodes. Prior studies have identified many factors that may contribute to the neuroinflammatory response to intracortical microelectrodes. Unfortunately, each proposed mechanism for the prolonged neuroinflammatory response has been investigated independently, while it is clear that mechanisms can overlap and be difficult to isolate. Therefore, we aimed to determine whether the dual targeting of the innate immune response by inhibiting innate immunity pathways associated with cluster of differentiation 14 (CD14), and the mechanical mismatch could improve the neuroinflammatory response to intracortical microelectrodes. A thiol-ene probe that softens on contact with the physiological environment was used to reduce mechanical mismatch. The thiol-ene probe was both softer and larger in size than the uncoated silicon control probe. Cd14-/- mice were used to completely inhibit contribution of CD14 to the neuroinflammatory response. Contrary to the initial hypothesis, dual targeting worsened the neuroinflammatory response to intracortical probes. Therefore, probe material and CD14 deficiency were independently assessed for their effect on inflammation and neuronal density by implanting each microelectrode type in both wild-type control and Cd14-/- mice. Histology results show that 2 weeks after implantation, targeting CD14 results in higher neuronal density and decreased glial scar around the probe, whereas the thiol-ene probe results in more microglia/macrophage activation and greater blood-brain barrier (BBB) disruption around the probe. Chronic histology demonstrate no differences in the inflammatory response at 16 weeks. Over acute time points, results also suggest immunomodulatory approaches such as targeting CD14 can be utilized to decrease inflammation to intracortical microelectrodes. The results obtained in the current study highlight the importance of not only probe material, but probe size, in regard to neuroinflammation.
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Affiliation(s)
- Hillary W. Bedell
- Department of Biomedical Engineering, School of Engineering, Case Western Reserve University, Cleveland, OH, United States
- Advanced Platform Technology Center, L. Stokes Cleveland VA Medical Center, Rehab. R&D, Cleveland, OH, United States
| | - Sydney Song
- Department of Biomedical Engineering, School of Engineering, Case Western Reserve University, Cleveland, OH, United States
- Advanced Platform Technology Center, L. Stokes Cleveland VA Medical Center, Rehab. R&D, Cleveland, OH, United States
| | - Xujia Li
- Department of Biomedical Engineering, School of Engineering, Case Western Reserve University, Cleveland, OH, United States
| | - Emily Molinich
- Department of Biomedical Engineering, School of Engineering, Case Western Reserve University, Cleveland, OH, United States
| | - Shushen Lin
- Department of Biomedical Engineering, School of Engineering, Case Western Reserve University, Cleveland, OH, United States
| | - Allison Stiller
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Vindhya Danda
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
- Center for Engineering Innovation, The University of Texas at Dallas, Richardson, TX, United States
| | - Melanie Ecker
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
- Center for Engineering Innovation, The University of Texas at Dallas, Richardson, TX, United States
- Department of Materials Science and Engineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Andrew J. Shoffstall
- Department of Biomedical Engineering, School of Engineering, Case Western Reserve University, Cleveland, OH, United States
- Advanced Platform Technology Center, L. Stokes Cleveland VA Medical Center, Rehab. R&D, Cleveland, OH, United States
| | - Walter E. Voit
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
- Center for Engineering Innovation, The University of Texas at Dallas, Richardson, TX, United States
- Department of Materials Science and Engineering, The University of Texas at Dallas, Richardson, TX, United States
- Department of Mechanical Engineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Joseph J. Pancrazio
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Jeffrey R. Capadona
- Department of Biomedical Engineering, School of Engineering, Case Western Reserve University, Cleveland, OH, United States
- Advanced Platform Technology Center, L. Stokes Cleveland VA Medical Center, Rehab. R&D, Cleveland, OH, United States
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75
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Kawaguchi Y. Pyramidal Cell Subtypes and Their Synaptic Connections in Layer 5 of Rat Frontal Cortex. Cereb Cortex 2018; 27:5755-5771. [PMID: 29028949 DOI: 10.1093/cercor/bhx252] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 09/06/2017] [Indexed: 12/31/2022] Open
Abstract
The frontal cortical areas make a coordinated response that generates appropriate behavior commands, using individual local circuits with corticostriatal and corticocortical connections in longer time scales than sensory areas. In secondary motor cortex (M2), situated between the prefrontal and primary motor areas, major subtypes of layer 5 corticostriatal cells are crossed-corticostriatal (CCS) cells innervating both sides of striatum, and corticopontine (CPn) cells projecting to the ipsilateral striatum and pontine nuclei. CCS cells innervate CPn cells unidirectionally: the former are therefore hierarchically higher than the latter among L5 corticostriatal cells. CCS cells project directly to both frontal and nonfrontal areas. On the other hand, CPn cells innervate the thalamus and layer 1a of frontal areas, where thalamic fibers relaying basal ganglia outputs are distributed. Thus, CCS cells can make activities of frontal areas in concert with those of nonfrontal area using corticocortical loops, whereas CPn cells are more involved in closed corticostriatal loops than CCS cells. Since reciprocal connections between CPn cells with facilitatory synapses may be related to persistent activity, CPn cells play a key role of longer time constant processes in corticostriatal as well as in corticocortical loops between the frontal areas.
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Affiliation(s)
- Yasuo Kawaguchi
- Division of Cerebral Circuitry, National Institute for Physiological Sciences, Okazaki 444-8787, Japan.,Department of Physiological Sciences, SOKENDAI (Graduate University for Advanced Studies), Okazaki, Japan
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76
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D5 dopamine receptors control glutamatergic AMPA transmission between the motor cortex and subthalamic nucleus. Sci Rep 2018; 8:8858. [PMID: 29891970 PMCID: PMC5995923 DOI: 10.1038/s41598-018-27195-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 05/25/2018] [Indexed: 12/23/2022] Open
Abstract
Corticofugal fibers target the subthalamic nucleus (STN), a component nucleus of the basal ganglia, in addition to the striatum, their main input. The cortico-subthalamic, or hyperdirect, pathway, is thought to supplement the cortico-striatal pathways in order to interrupt/change planned actions. To explore the previously unknown properties of the neurons that project to the STN, retrograde and anterograde tools were used to specifically identify them in the motor cortex and selectively stimulate their synapses in the STN. The cortico-subthalamic neurons exhibited very little sag and fired an initial doublet followed by non-adapting action potentials. In the STN, AMPA/kainate synaptic currents had a voltage-dependent conductance, indicative of GluA2-lacking receptors and were partly inhibited by Naspm. AMPA transmission displayed short-term depression, with the exception of a limited bandpass in the 5 to 15 Hz range. AMPA synaptic currents were negatively controlled by dopamine D5 receptors. The reduction in synaptic strength was due to postsynaptic D5 receptors, mediated by a PKA-dependent pathway, but did not involve a modified rectification index. Our data indicated that dopamine, through post-synaptic D5 receptors, limited the cortical drive onto STN neurons in the normal brain.
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Handley EE, Pitman KA, Dawkins E, Young KM, Clark RM, Jiang TC, Turner BJ, Dickson TC, Blizzard CA. Synapse Dysfunction of Layer V Pyramidal Neurons Precedes Neurodegeneration in a Mouse Model of TDP-43 Proteinopathies. Cereb Cortex 2018; 27:3630-3647. [PMID: 27496536 DOI: 10.1093/cercor/bhw185] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
TDP-43 is a major protein component of pathological neuronal inclusions that are present in frontotemporal dementia and amyotrophic lateral sclerosis. We report that TDP-43 plays an important role in dendritic spine formation in the cortex. The density of spines on YFP+ pyramidal neurons in both the motor and somatosensory cortex of Thy1-YFP mice, increased significantly from postnatal day 30 (P30), to peak at P60, before being pruned by P90. By comparison, dendritic spine density was significantly reduced in the motor cortex of Thy1-YFP::TDP-43A315T transgenic mice prior to symptom onset (P60), and in the motor and somatosensory cortex at symptom onset (P90). Morphological spine-type analysis revealed that there was a significant impairment in the development of basal mushroom spines in the motor cortex of Thy1-YFP::TDP-43A315T mice compared to Thy1-YFP control. Furthermore, reductions in spine density corresponded to mislocalisation of TDP-43 immunoreactivity and lowered efficacy of synaptic transmission as determined by electrophysiology at P60. We conclude that mutated TDP-43 has a significant pathological effect at the dendritic spine that is associated with attenuated neural transmission.
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Affiliation(s)
- Emily E Handley
- Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS 7000, Australia
| | - Kimberley A Pitman
- Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS 7000, Australia
| | - Edgar Dawkins
- Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS 7000, Australia
| | - Kaylene M Young
- Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS 7000, Australia
| | - Rosemary M Clark
- Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS 7000, Australia
| | - Tongcui C Jiang
- Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS 7000, Australia
| | - Bradley J Turner
- Florey Institute for Neuroscience and Mental Health, University of Melbourne, Melbourne, VIC 3052, Australia
| | - Tracey C Dickson
- Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS 7000, Australia
| | - Catherine A Blizzard
- Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS 7000, Australia
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78
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Specialized Subpopulations of Deep-Layer Pyramidal Neurons in the Neocortex: Bridging Cellular Properties to Functional Consequences. J Neurosci 2018; 38:5441-5455. [PMID: 29798890 DOI: 10.1523/jneurosci.0150-18.2018] [Citation(s) in RCA: 92] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 05/09/2018] [Accepted: 05/11/2018] [Indexed: 12/25/2022] Open
Abstract
Neocortical pyramidal neurons with somata in layers 5 and 6 are among the most visually striking and enigmatic neurons in the brain. These deep-layer pyramidal neurons (DLPNs) integrate a plethora of cortical and extracortical synaptic inputs along their impressive dendritic arbors. The pattern of cortical output to both local and long-distance targets is sculpted by the unique physiological properties of specific DLPN subpopulations. Here we revisit two broad DLPN subpopulations: those that send their axons within the telencephalon (intratelencephalic neurons) and those that project to additional target areas outside the telencephalon (extratelencephalic neurons). While neuroscientists across many subdisciplines have characterized the intrinsic and synaptic physiological properties of DLPN subpopulations, our increasing ability to selectively target and manipulate these output neuron subtypes advances our understanding of their distinct functional contributions. This Viewpoints article summarizes our current knowledge about DLPNs and highlights recent work elucidating the functional differences between DLPN subpopulations.
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79
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Bedell HW, Hermann JK, Ravikumar M, Lin S, Rein A, Li X, Molinich E, Smith PD, Selkirk SM, Miller RH, Sidik S, Taylor DM, Capadona JR. Targeting CD14 on blood derived cells improves intracortical microelectrode performance. Biomaterials 2018; 163:163-173. [PMID: 29471127 PMCID: PMC5841759 DOI: 10.1016/j.biomaterials.2018.02.014] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 01/31/2018] [Accepted: 02/07/2018] [Indexed: 01/02/2023]
Abstract
Intracortical microelectrodes afford researchers an effective tool to precisely monitor neural spiking activity. Additionally, intracortical microelectrodes have the ability to return function to individuals with paralysis as part of a brain computer interface. Unfortunately, the neural signals recorded by these electrodes degrade over time. Many strategies which target the biological and/or materials mediating failure modes of this decline of function are currently under investigation. The goal of this study is to identify a precise cellular target for future intervention to sustain chronic intracortical microelectrode performance. Previous work from our lab has indicated that the Cluster of Differentiation 14/Toll-like receptor pathway (CD14/TLR) is a viable target to improve chronic laminar, silicon intracortical microelectrode recordings. Here, we use a mouse bone marrow chimera model to selectively knockout CD14, an innate immune receptor, from either brain resident microglia or blood-derived macrophages, in order to understand the most effective targets for future therapeutic options. Using single-unit recordings we demonstrate that inhibiting CD14 from the blood-derived macrophages improves recording quality over the 16 week long study. We conclude that targeting CD14 in blood-derived cells should be part of the strategy to improve the performance of intracortical microelectrodes, and that the daunting task of delivering therapeutics across the blood-brain barrier may not be needed to increase intracortical microelectrode performance.
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Affiliation(s)
- Hillary W Bedell
- Department of Biomedical Engineering, Case Western Reserve University, School of Engineering, 2071 MLK Jr. Drive, Wickenden Bldg, Cleveland, OH 44106, USA; Advanced Platform Technology Center, L. Stokes Cleveland VA Medical Center, Rehab. R&D, 10701 East Blvd. Mail Stop 151 AW/APT, Cleveland, OH 44106, USA
| | - John K Hermann
- Department of Biomedical Engineering, Case Western Reserve University, School of Engineering, 2071 MLK Jr. Drive, Wickenden Bldg, Cleveland, OH 44106, USA; Advanced Platform Technology Center, L. Stokes Cleveland VA Medical Center, Rehab. R&D, 10701 East Blvd. Mail Stop 151 AW/APT, Cleveland, OH 44106, USA
| | - Madhumitha Ravikumar
- Department of Biomedical Engineering, Case Western Reserve University, School of Engineering, 2071 MLK Jr. Drive, Wickenden Bldg, Cleveland, OH 44106, USA; Advanced Platform Technology Center, L. Stokes Cleveland VA Medical Center, Rehab. R&D, 10701 East Blvd. Mail Stop 151 AW/APT, Cleveland, OH 44106, USA
| | - Shushen Lin
- Department of Biomedical Engineering, Case Western Reserve University, School of Engineering, 2071 MLK Jr. Drive, Wickenden Bldg, Cleveland, OH 44106, USA
| | - Ashley Rein
- Department of Biomedical Engineering, Case Western Reserve University, School of Engineering, 2071 MLK Jr. Drive, Wickenden Bldg, Cleveland, OH 44106, USA
| | - Xujia Li
- Department of Biomedical Engineering, Case Western Reserve University, School of Engineering, 2071 MLK Jr. Drive, Wickenden Bldg, Cleveland, OH 44106, USA
| | - Emily Molinich
- Department of Biomedical Engineering, Case Western Reserve University, School of Engineering, 2071 MLK Jr. Drive, Wickenden Bldg, Cleveland, OH 44106, USA
| | - Patrick D Smith
- Department of Biomedical Engineering, Case Western Reserve University, School of Engineering, 2071 MLK Jr. Drive, Wickenden Bldg, Cleveland, OH 44106, USA
| | - Stephen M Selkirk
- Advanced Platform Technology Center, L. Stokes Cleveland VA Medical Center, Rehab. R&D, 10701 East Blvd. Mail Stop 151 AW/APT, Cleveland, OH 44106, USA
| | - Robert H Miller
- Neurosciences, The George Washington University, The School of Medicine & Health Sciences, 2300 Eye Street, NW, Ross Hall, Washington DC 20037, USA
| | - Steven Sidik
- Department of Mathematics, Applied Mathematics and Statistics, Case Western Reserve University, 2049 Martin Luther King Jr. Drive, Yost Hall, Cleveland, OH 44106, USA
| | - Dawn M Taylor
- Department of Biomedical Engineering, Case Western Reserve University, School of Engineering, 2071 MLK Jr. Drive, Wickenden Bldg, Cleveland, OH 44106, USA; Department of Neurosciences, Cleveland Clinic Lerner Research Institute, 9500 Euclid Avenue, Cleveland, OH 44195, USA
| | - Jeffrey R Capadona
- Department of Biomedical Engineering, Case Western Reserve University, School of Engineering, 2071 MLK Jr. Drive, Wickenden Bldg, Cleveland, OH 44106, USA; Advanced Platform Technology Center, L. Stokes Cleveland VA Medical Center, Rehab. R&D, 10701 East Blvd. Mail Stop 151 AW/APT, Cleveland, OH 44106, USA.
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80
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Popovitchenko T, Rasin MR. Transcriptional and Post-Transcriptional Mechanisms of the Development of Neocortical Lamination. Front Neuroanat 2017; 11:102. [PMID: 29170632 PMCID: PMC5684109 DOI: 10.3389/fnana.2017.00102] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 10/25/2017] [Indexed: 12/31/2022] Open
Abstract
The neocortex is a laminated brain structure that is the seat of higher cognitive capacity and responses, long-term memory, sensory and emotional functions, and voluntary motor behavior. Proper lamination requires that progenitor cells give rise to a neuron, that the immature neuron can migrate away from its mother cell and past other cells, and finally that the immature neuron can take its place and adopt a mature identity characterized by connectivity and gene expression; thus lamination proceeds through three steps: genesis, migration, and maturation. Each neocortical layer contains pyramidal neurons that share specific morphological and molecular characteristics that stem from their prenatal birth date. Transcription factors are dynamic proteins because of the cohort of downstream factors that they regulate. RNA-binding proteins are no less dynamic, and play important roles in every step of mRNA processing. Indeed, recent screens have uncovered post-transcriptional mechanisms as being integral regulatory mechanisms to neocortical development. Here, we summarize major aspects of neocortical laminar development, emphasizing transcriptional and post-transcriptional mechanisms, with the aim of spurring increased understanding and study of its intricacies.
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Affiliation(s)
- Tatiana Popovitchenko
- Neuroscience and Cell Biology, Robert Wood Johnson Medical School, New Brunswick, NJ, United States
| | - Mladen-Roko Rasin
- Neuroscience and Cell Biology, Robert Wood Johnson Medical School, New Brunswick, NJ, United States
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81
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Höfflin F, Jack A, Riedel C, Mack-Bucher J, Roos J, Corcelli C, Schultz C, Wahle P, Engelhardt M. Heterogeneity of the Axon Initial Segment in Interneurons and Pyramidal Cells of Rodent Visual Cortex. Front Cell Neurosci 2017; 11:332. [PMID: 29170630 PMCID: PMC5684645 DOI: 10.3389/fncel.2017.00332] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 10/09/2017] [Indexed: 11/13/2022] Open
Abstract
The microdomain that orchestrates action potential initiation in neurons is the axon initial segment (AIS). It has long been considered to be a rather homogeneous domain at the very proximal axon hillock with relatively stable length, particularly in cortical pyramidal cells. However, studies in other brain regions paint a different picture. In hippocampal CA1, up to 50% of axons emerge from basal dendrites. Further, in about 30% of thick-tufted layer V pyramidal neurons in rat somatosensory cortex, axons have a dendritic origin. Consequently, the AIS is separated from the soma. Recent in vitro and in vivo studies have shown that cellular excitability is a function of AIS length/position and somatodendritic morphology, undermining a potentially significant impact of AIS heterogeneity for neuronal function. We therefore investigated neocortical axon morphology and AIS composition, hypothesizing that the initial observation of seemingly homogeneous AIS is inadequate and needs to take into account neuronal cell types. Here, we biolistically transfected cortical neurons in organotypic cultures to visualize the entire neuron and classify cell types in combination with immunolabeling against AIS markers. Using confocal microscopy and morphometric analysis, we investigated axon origin, AIS position, length, diameter as well as distance to the soma. We find a substantial AIS heterogeneity in visual cortical neurons, classified into three groups: (I) axons with somatic origin with proximal AIS at the axon hillock; (II) axons with somatic origin with distal AIS, with a discernible gap between the AIS and the soma; and (III) axons with dendritic origin (axon-carrying dendrite cell, AcD cell) and an AIS either starting directly at the axon origin or more distal to that point. Pyramidal cells have significantly longer AIS than interneurons. Interneurons with vertical columnar axonal projections have significantly more distal AIS locations than all other cells with their prevailing phenotype as an AcD cell. In contrast, neurons with perisomatic terminations display most often an axon originating from the soma. Our data contribute to the emerging understanding that AIS morphology is highly variable, and potentially a function of the cell type.
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Affiliation(s)
- Felix Höfflin
- Institute of Neuroanatomy, Medical Faculty Mannheim, Center for Biomedicine and Medical Technology Mannheim (CBTM), Heidelberg University, Heidelberg, Germany
| | - Alexander Jack
- Developmental Neurobiology, Department of Zoology and Neurobiology, Ruhr-University Bochum, Bochum, Germany
| | - Christian Riedel
- Developmental Neurobiology, Department of Zoology and Neurobiology, Ruhr-University Bochum, Bochum, Germany
| | - Julia Mack-Bucher
- Live Cell Imaging Core Mannheim (LIMA), Medical Faculty Mannheim, Center for Biomedicine and Medical Technology Mannheim (CBTM), Heidelberg University, Heidelberg, Germany
| | - Johannes Roos
- Institute of Neuroanatomy, Medical Faculty Mannheim, Center for Biomedicine and Medical Technology Mannheim (CBTM), Heidelberg University, Heidelberg, Germany
| | - Corinna Corcelli
- Institute of Neuroanatomy, Medical Faculty Mannheim, Center for Biomedicine and Medical Technology Mannheim (CBTM), Heidelberg University, Heidelberg, Germany
| | - Christian Schultz
- Institute of Neuroanatomy, Medical Faculty Mannheim, Center for Biomedicine and Medical Technology Mannheim (CBTM), Heidelberg University, Heidelberg, Germany
| | - Petra Wahle
- Developmental Neurobiology, Department of Zoology and Neurobiology, Ruhr-University Bochum, Bochum, Germany
| | - Maren Engelhardt
- Institute of Neuroanatomy, Medical Faculty Mannheim, Center for Biomedicine and Medical Technology Mannheim (CBTM), Heidelberg University, Heidelberg, Germany
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82
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Marked bias towards spontaneous synaptic inhibition distinguishes non-adapting from adapting layer 5 pyramidal neurons in the barrel cortex. Sci Rep 2017; 7:14959. [PMID: 29097689 PMCID: PMC5668277 DOI: 10.1038/s41598-017-14971-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 10/19/2017] [Indexed: 11/18/2022] Open
Abstract
Pyramidal neuron subtypes differ in intrinsic electrophysiology properties and dendritic morphology. However, do different pyramidal neuron subtypes also receive synaptic inputs that are dissimilar in frequency and in excitation/inhibition balance? Unsupervised clustering of three intrinsic parameters that vary by cell subtype – the slow afterhyperpolarization, the sag, and the spike frequency adaptation – split layer 5 barrel cortex pyramidal neurons into two clusters: one of adapting cells and one of non-adapting cells, corresponding to previously described thin- and thick-tufted pyramidal neurons, respectively. Non-adapting neurons presented frequencies of spontaneous inhibitory postsynaptic currents (sIPSCs) and spontaneous excitatory postsynaptic currents (sEPSCs) three- and two-fold higher, respectively, than those of adapting neurons. The IPSC difference between pyramidal subtypes was activity independent. A subset of neurons were thy1-GFP positive, presented characteristics of non-adapting pyramidal neurons, and also had higher IPSC and EPSC frequencies than adapting neurons. The sEPSC/sIPSC frequency ratio was higher in adapting than in non-adapting cells, suggesting a higher excitatory drive in adapting neurons. Therefore, our study on spontaneous synaptic inputs suggests a different extent of synaptic information processing in adapting and non-adapting barrel cortex neurons, and that eventual deficits in inhibition may have differential effects on the excitation/inhibition balance in adapting and non-adapting neurons.
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83
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Vitrac C, Benoit-Marand M. Monoaminergic Modulation of Motor Cortex Function. Front Neural Circuits 2017; 11:72. [PMID: 29062274 PMCID: PMC5640772 DOI: 10.3389/fncir.2017.00072] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Accepted: 09/19/2017] [Indexed: 01/09/2023] Open
Abstract
Elaboration of appropriate responses to behavioral situations rests on the ability of selecting appropriate motor outcomes in accordance to specific environmental inputs. To this end, the primary motor cortex (M1) is a key structure for the control of voluntary movements and motor skills learning. Subcortical loops regulate the activity of the motor cortex and thus contribute to the selection of appropriate motor plans. Monoamines are key mediators of arousal, attention and motivation. Their firing pattern enables a direct encoding of different states thus promoting or repressing the selection of actions adapted to the behavioral context. Monoaminergic modulation of motor systems has been extensively studied in subcortical circuits. Despite evidence of converging projections of multiple neurotransmitters systems in the motor cortex pointing to a direct modulation of local circuits, their contribution to the execution and learning of motor skills is still poorly understood. Monoaminergic dysregulation leads to impaired plasticity and motor function in several neurological and psychiatric conditions, thus it is critical to better understand how monoamines modulate neural activity in the motor cortex. This review aims to provide an update of our current understanding on the monoaminergic modulation of the motor cortex with an emphasis on motor skill learning and execution under physiological conditions.
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Affiliation(s)
- Clément Vitrac
- Laboratoire de Neurosciences Expérimentales et Cliniques, INSERM U1084, Poitiers, France.,Laboratoire de Neurosciences Expérimentales et Cliniques, Université de Poitiers, Poitiers, France
| | - Marianne Benoit-Marand
- Laboratoire de Neurosciences Expérimentales et Cliniques, INSERM U1084, Poitiers, France.,Laboratoire de Neurosciences Expérimentales et Cliniques, Université de Poitiers, Poitiers, France
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84
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Changes in the Excitability of Neocortical Neurons in a Mouse Model of Amyotrophic Lateral Sclerosis Are Not Specific to Corticospinal Neurons and Are Modulated by Advancing Disease. J Neurosci 2017; 37:9037-9053. [PMID: 28821643 PMCID: PMC5597984 DOI: 10.1523/jneurosci.0811-17.2017] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 07/22/2017] [Accepted: 08/06/2017] [Indexed: 12/13/2022] Open
Abstract
Cell type-specific changes in neuronal excitability have been proposed to contribute to the selective degeneration of corticospinal neurons in amyotrophic lateral sclerosis (ALS) and to neocortical hyperexcitability, a prominent feature of both inherited and sporadic variants of the disease, but the mechanisms underlying selective loss of specific cell types in ALS are not known. We analyzed the physiological properties of distinct classes of cortical neurons in the motor cortex of hSOD1G93A mice of both sexes and found that they all exhibit increases in intrinsic excitability that depend on disease stage. Targeted recordings and in vivo calcium imaging further revealed that neurons adapt their functional properties to normalize cortical excitability as the disease progresses. Although different neuron classes all exhibited increases in intrinsic excitability, transcriptional profiling indicated that the molecular mechanisms underlying these changes are cell type specific. The increases in excitability in both excitatory and inhibitory cortical neurons show that selective dysfunction of neuronal cell types cannot account for the specific vulnerability of corticospinal motor neurons in ALS. Furthermore, the stage-dependent alterations in neuronal function highlight the ability of cortical circuits to adapt as disease progresses. These findings show that both disease stage and cell type must be considered when developing therapeutic strategies for treating ALS.SIGNIFICANCE STATEMENT It is not known why certain classes of neurons preferentially die in different neurodegenerative diseases. It has been proposed that the enhanced excitability of affected neurons is a major contributor to their selective loss. We show using a mouse model of amyotrophic lateral sclerosis (ALS), a disease in which corticospinal neurons exhibit selective vulnerability, that changes in excitability are not restricted to this neuronal class and that excitability does not increase monotonically with disease progression. Moreover, although all neuronal cell types tested exhibited abnormal functional properties, analysis of their gene expression demonstrated cell type-specific responses to the ALS-causing mutation. These findings suggest that therapies for ALS may need to be tailored for different cell types and stages of disease.
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85
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Peters AJ, Lee J, Hedrick NG, O’Neil K, Komiyama T. Reorganization of corticospinal output during motor learning. Nat Neurosci 2017; 20:1133-1141. [PMID: 28671694 PMCID: PMC5656286 DOI: 10.1038/nn.4596] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 05/30/2017] [Indexed: 02/08/2023]
Abstract
Motor learning is accompanied by widespread changes within the motor cortex, but it is unknown whether these changes are ultimately funneled through a stable corticospinal output channel or whether the corticospinal output itself is plastic. We investigated the consistency of the relationship between corticospinal neuron activity and movement through in vivo two-photon calcium imaging in mice learning a lever-press task. Corticospinal neurons exhibited heterogeneous correlations with movement, with the majority of movement-modulated neurons decreasing activity during movement. Individual cells changed their activity across days, which led to changed associations between corticospinal activity and movement. Unlike previous observations in layer 2/3, activity accompanying learned movements did not become more consistent with learning; instead, the activity of dissimilar movements became more decorrelated. These results indicate that the relationship between corticospinal activity and movement is dynamic and that the types of activity and plasticity are different from and possibly complementary to those in layer 2/3.
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Affiliation(s)
- Andrew J. Peters
- Neurobiology Section, Center for Neural Circuits and Behavior, and Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Jun Lee
- Neurobiology Section, Center for Neural Circuits and Behavior, and Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Nathan G. Hedrick
- Neurobiology Section, Center for Neural Circuits and Behavior, and Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Keelin O’Neil
- Neurobiology Section, Center for Neural Circuits and Behavior, and Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Takaki Komiyama
- Neurobiology Section, Center for Neural Circuits and Behavior, and Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093, USA
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86
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Li Q, Ko H, Qian ZM, Yan LYC, Chan DCW, Arbuthnott G, Ke Y, Yung WH. Refinement of learned skilled movement representation in motor cortex deep output layer. Nat Commun 2017; 8:15834. [PMID: 28598433 PMCID: PMC5472789 DOI: 10.1038/ncomms15834] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2016] [Accepted: 04/26/2017] [Indexed: 01/06/2023] Open
Abstract
The mechanisms underlying the emergence of learned motor skill representation in primary motor cortex (M1) are not well understood. Specifically, how motor representation in the deep output layer 5b (L5b) is shaped by motor learning remains virtually unknown. In rats undergoing motor skill training, we detect a subpopulation of task-recruited L5b neurons that not only become more movement-encoding, but their activities are also more structured and temporally aligned to motor execution with a timescale of refinement in tens-of-milliseconds. Field potentials evoked at L5b in vivo exhibit persistent long-term potentiation (LTP) that parallels motor performance. Intracortical dopamine denervation impairs motor learning, and disrupts the LTP profile as well as the emergent neurodynamical properties of task-recruited L5b neurons. Thus, dopamine-dependent recruitment of L5b neuronal ensembles via synaptic reorganization may allow the motor cortex to generate more temporally structured, movement-encoding output signal from M1 to downstream circuitry that drives increased uniformity and precision of movement during motor learning.
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Affiliation(s)
- Qian Li
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
| | - Ho Ko
- Department of Medicine and Therapeutics, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
- Li Ka Shing Institute of Health Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
- Gerald Choa Neuroscience Centre, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
- Chow Yuk Ho Technology Center for Innovative Medicine, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
| | - Zhong-Ming Qian
- Laboratory of Neuropharmacology, School of Pharmacy, Fudan University, Shanghai 201203, China
| | - Leo Y. C. Yan
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
- Gerald Choa Neuroscience Centre, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
| | - Danny C. W. Chan
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
- Gerald Choa Neuroscience Centre, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
| | - Gordon Arbuthnott
- Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan 904-0495
| | - Ya Ke
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
- Gerald Choa Neuroscience Centre, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
- Chow Yuk Ho Technology Center for Innovative Medicine, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
| | - Wing-Ho Yung
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
- Gerald Choa Neuroscience Centre, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
- Chow Yuk Ho Technology Center for Innovative Medicine, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
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87
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Chovsepian A, Empl L, Correa D, Bareyre FM. Heterotopic Transcallosal Projections Are Present throughout the Mouse Cortex. Front Cell Neurosci 2017; 11:36. [PMID: 28270750 PMCID: PMC5318386 DOI: 10.3389/fncel.2017.00036] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2016] [Accepted: 02/06/2017] [Indexed: 11/13/2022] Open
Abstract
Transcallosal projection neurons are a population of pyramidal excitatory neurons located in layers II/III and to a lesser extent layer V of the cortex. Their axons form the corpus callosum thereby providing an inter-hemispheric connection in the brain. While transcallosal projection neurons have been described in some detail before, it is so far unclear whether they are uniformly organized throughout the cortex or whether different functional regions of the cortex contain distinct adaptations of their transcallosal connectivity. To address this question, we have therefore conducted a systematic analysis of transcallosal projection neurons and their axons across six distinct stereotactic coordinates in the mouse cortex that cover different areas of the motor and somatosensory cortices. Using anterograde and retrograde tracing techniques, we found that in agreement with previous studies, most of the transcallosal projections show a precise homotopic organization. The somata of these neurons are predominantly located in layer II/III and layer V but notably smaller numbers of these cells are also found in layer IV and layer VI. In addition, regional differences in the distribution of their somata and the precision of their projections exist indicating that while transcallosal neurons show a uniform organization throughout the mouse cortex, there is a sizeable fraction of these connections that are heterotopic. Our study thus provides a comprehensive characterization of transcallosal connectivity in different cortical areas that can serve as the basis for further investigations of the establishment of inter-hemispheric projections in development and their alterations in disease.
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Affiliation(s)
- Alexandra Chovsepian
- Institute of Clinical Neuroimmunology, Biomedical Center and University Hospital, Ludwig-Maximilians Universität München Munich, Germany
| | - Laura Empl
- Institute of Clinical Neuroimmunology, Biomedical Center and University Hospital, Ludwig-Maximilians Universität München Munich, Germany
| | - Daphne Correa
- Institute of Clinical Neuroimmunology, Biomedical Center and University Hospital, Ludwig-Maximilians Universität München Munich, Germany
| | - Florence M Bareyre
- Institute of Clinical Neuroimmunology, Biomedical Center and University Hospital, Ludwig-Maximilians Universität MünchenMunich, Germany; Munich Cluster of System Neurology (SyNergy), Ludwig-Maximilians Universität MünchenMunich, Germany
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88
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Vasques X, Vanel L, Villette G, Cif L. Morphological Neuron Classification Using Machine Learning. Front Neuroanat 2016; 10:102. [PMID: 27847467 PMCID: PMC5088188 DOI: 10.3389/fnana.2016.00102] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2016] [Accepted: 10/07/2016] [Indexed: 01/20/2023] Open
Abstract
Classification and quantitative characterization of neuronal morphologies from histological neuronal reconstruction is challenging since it is still unclear how to delineate a neuronal cell class and which are the best features to define them by. The morphological neuron characterization represents a primary source to address anatomical comparisons, morphometric analysis of cells, or brain modeling. The objectives of this paper are (i) to develop and integrate a pipeline that goes from morphological feature extraction to classification and (ii) to assess and compare the accuracy of machine learning algorithms to classify neuron morphologies. The algorithms were trained on 430 digitally reconstructed neurons subjectively classified into layers and/or m-types using young and/or adult development state population of the somatosensory cortex in rats. For supervised algorithms, linear discriminant analysis provided better classification results in comparison with others. For unsupervised algorithms, the affinity propagation and the Ward algorithms provided slightly better results.
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Affiliation(s)
- Xavier Vasques
- Laboratoire de Recherche en Neurosciences CliniquesSaint-André-de-Sangonis, France
- International Business Machines Corporation SystemsParis, France
| | - Laurent Vanel
- International Business Machines Corporation SystemsParis, France
| | | | - Laura Cif
- Département de Neurochirurgie, Hôpital Gui de Chauliac, Centre Hospitalier
Régional Universitaire de MontpellierMontpellier, France
- Université de Montpellier 1Montpellier, France
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89
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Kaufmann TJ, Harrison PM, Richardson MJE, Pinheiro TJT, Wall MJ. Intracellular soluble α-synuclein oligomers reduce pyramidal cell excitability. J Physiol 2016; 594:2751-72. [PMID: 26915902 PMCID: PMC4865569 DOI: 10.1113/jp271968] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 02/17/2016] [Indexed: 02/04/2023] Open
Abstract
Key points The presynaptic protein α‐synuclein forms aggregates during Parkinson's disease. Accumulating evidence suggests that the small soluble oligomers of α‐synuclein are more toxic than the larger aggregates appearing later in the disease. The link between oligomer toxicity and structure still remains unclear. In the present study, we have produced two structurally‐defined oligomers that have a similar morphology but differ in secondary structure. These oligomers were introduced into neocortical pyramidal cells during whole‐cell recording and, using a combination of experimentation and modelling, electrophysiological parameters were extracted. Both oligomeric species had similar effects on neuronal properties reducing input resistance, time constant and increasing capacitance. The net effect was a marked reduction in neuronal excitability that could impact on network activity.
Abstract The presynaptic protein α‐synuclein (αSyn) aggregates during Parkinson's disease (PD) to form large proteinaceous amyloid plaques, the spread of which throughout the brain clinically defines the severity of the disease. During early stages of aggregation, αSyn forms soluble annular oligomers that show greater toxicity than much larger fibrils. These oligomers produce toxicity via a number of possible mechanisms, including the production of pore‐forming complexes that permeabilize membranes. In the present study, two well‐defined species of soluble αSyn oligomers were produced by different protocols: by polymerization of monomer and by sonication of fibrils. The two oligomeric species produced were morphologically similar, with both having an annular structure and consisting of approximately the same number of monomer subunits, although they differed in their secondary structure. Oligomeric and monomeric αSyn were injected directly into the soma of pyramidal neurons in mouse neocortical brain slices during whole‐cell patch clamp recording. Using a combined experimental and modelling approach, neuronal parameters were extracted to measure, for the first time in the neocortex, specific changes in neuronal electrophysiology. Both species of oligomer had similar effects: (i) a significant reduction in input resistance and the membrane time constant and (ii) an increase in the current required to trigger an action potential with a resultant reduction in the firing rate. Differences in oligomer secondary structure appeared to produce only subtle differences in the activity of the oligomers. Monomeric αSyn had no effect on neuronal parameters, even at high concentrations. The oligomer‐induced fall in neuronal excitability has the potential to impact both network activity and cognitive processing. The presynaptic protein α‐synuclein forms aggregates during Parkinson's disease. Accumulating evidence suggests that the small soluble oligomers of α‐synuclein are more toxic than the larger aggregates appearing later in the disease. The link between oligomer toxicity and structure still remains unclear. In the present study, we have produced two structurally‐defined oligomers that have a similar morphology but differ in secondary structure. These oligomers were introduced into neocortical pyramidal cells during whole‐cell recording and, using a combination of experimentation and modelling, electrophysiological parameters were extracted. Both oligomeric species had similar effects on neuronal properties reducing input resistance, time constant and increasing capacitance. The net effect was a marked reduction in neuronal excitability that could impact on network activity.
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Affiliation(s)
| | - Paul M Harrison
- Warwick Systems Biology Centre, University of Warwick, Coventry, UK
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90
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Instructing Perisomatic Inhibition by Direct Lineage Reprogramming of Neocortical Projection Neurons. Neuron 2016; 88:475-83. [PMID: 26539889 DOI: 10.1016/j.neuron.2015.10.006] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Revised: 07/07/2015] [Accepted: 09/21/2015] [Indexed: 11/23/2022]
Abstract
During development of the cerebral cortex, local GABAergic interneurons recognize and pair with excitatory projection neurons to ensure the fine excitatory-inhibitory balance essential for proper circuit function. Whether the class-specific identity of projection neurons has a role in the establishment of afferent inhibitory synapses is debated. Here, we report that direct in vivo lineage reprogramming of layer 2/3 (L2/3) callosal projection neurons (CPNs) into induced corticofugal projection neurons (iCFuPNs) increases inhibitory input onto the converted neurons to levels similar to that of endogenous CFuPNs normally found in layer 5 (L5). iCFuPNs recruit increased numbers of inhibitory perisomatic synapses from parvalbumin (PV)-positive interneurons, with single-cell precision and despite their ectopic location in L2/3. The data show that individual reprogrammed excitatory projection neurons extrinsically modulate afferent input by local PV(+) interneurons, suggesting that projection neuron class-specific identity can actively control the wiring of the cortical microcircuit.
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91
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Pardillo-Díaz R, Carrascal L, Muñoz MF, Ayala A, Nunez-Abades P. Time and dose dependent effects of oxidative stress induced by cumene hydroperoxide in neuronal excitability of rat motor cortex neurons. Neurotoxicology 2016; 53:201-214. [PMID: 26877221 DOI: 10.1016/j.neuro.2016.02.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 01/22/2016] [Accepted: 02/09/2016] [Indexed: 12/19/2022]
Abstract
It has been claimed that oxidative stress and the production of reactive oxygen radicals can contribute to neuron degeneration and might be one factor in the development of different neurological diseases. In our study, we have attempted to clarify how oxidative damage induces dose dependent changes in functional membrane properties of neurons by means of whole cell patch clamp techniques in brain slices from young adult rats. Our research demonstrates physiological changes in membrane properties of pyramidal motor cortex neurons exposed to 3 concentrations of cumene hydroperoxide (CH; 1, 10 and 100μM) during 30min. Results show that oxidative stress induced by CH evokes important changes, in a concentration and time dependent manner, in the neuronal excitability of motor cortex neurons of the rat: (i) Low concentration of the drug (1μM) already blocks inward rectifications (sag) and decreases action potential amplitude and gain, a drug concentration which has no effects on other neuronal populations, (ii) 10μM of CH depresses the excitability of pyramidal motor cortex neurons by decreasing input resistance, amplitude of the action potential, and gain and maximum frequency of the repetitive firing discharge, and (iii) 100μM completely blocks the capability to produce repetitive discharge of action potentials in all cells. Both larger drug concentrations and/or longer times of exposure to CH narrow the current working range. This happens because of the increase in the rheobase, and the reduction of the cancelation current. The effects caused by oxidative stress, including those produced by the level of lipid peroxidation, are practically irreversible and, this, therefore, indicates that neuroprotective agents should be administered at the first symptoms of alterations to membrane properties. In fact, the pre-treatment with melatonin, acting as an antioxidant, prevented the lipid peroxidation and the physiological changes induced by CH. Larger cells (as estimated by their cell capacitance) were also more susceptible to oxidative stress. Our results provide previously unavailable observations that large size and high sensitivity to oxidative stress (even at low concentrations) make pyramidal neurons of the motor cortex, in particular corticofugal neurons, more susceptible to cell death when compared with other neuronal populations. These results could also shed some light on explaining the causes behind diseases such as Amyotrophic Lateral Sclerosis.
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Affiliation(s)
- R Pardillo-Díaz
- Department of Physiology, School of Pharmacy, University of Seville, Spain
| | - L Carrascal
- Department of Physiology, School of Pharmacy, University of Seville, Spain
| | - M F Muñoz
- Department of Biochemistry and Molecular Biology, School of Pharmacy, University of Seville, Spain
| | - A Ayala
- Department of Biochemistry and Molecular Biology, School of Pharmacy, University of Seville, Spain
| | - P Nunez-Abades
- Department of Physiology, School of Pharmacy, University of Seville, Spain.
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92
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Harb K, Magrinelli E, Nicolas CS, Lukianets N, Frangeul L, Pietri M, Sun T, Sandoz G, Grammont F, Jabaudon D, Studer M, Alfano C. Area-specific development of distinct projection neuron subclasses is regulated by postnatal epigenetic modifications. eLife 2016; 5:e09531. [PMID: 26814051 PMCID: PMC4744182 DOI: 10.7554/elife.09531] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 12/13/2015] [Indexed: 12/25/2022] Open
Abstract
During cortical development, the identity of major classes of long-distance projection neurons is established by the expression of molecular determinants, which become gradually restricted and mutually exclusive. However, the mechanisms by which projection neurons acquire their final properties during postnatal stages are still poorly understood. In this study, we show that the number of neurons co-expressing Ctip2 and Satb2, respectively involved in the early specification of subcerebral and callosal projection neurons, progressively increases after birth in the somatosensory cortex. Ctip2/Satb2 postnatal co-localization defines two distinct neuronal subclasses projecting either to the contralateral cortex or to the brainstem suggesting that Ctip2/Satb2 co-expression may refine their properties rather than determine their identity. Gain- and loss-of-function approaches reveal that the transcriptional adaptor Lmo4 drives this maturation program through modulation of epigenetic mechanisms in a time- and area-specific manner, thereby indicating that a previously unknown genetic program postnatally promotes the acquisition of final subtype-specific features.
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Affiliation(s)
- Kawssar Harb
- Institut de Biologie Valrose, University of Nice Sophia Antipolis, Nice, France.,Institut de Biologie Valrose, Institut national de la santé et de la recherche médicale, Nice, France.,Centre national de la recherche scientifique, Institut de Biologie Valrose, Nice, France
| | - Elia Magrinelli
- Institut de Biologie Valrose, University of Nice Sophia Antipolis, Nice, France.,Institut de Biologie Valrose, Institut national de la santé et de la recherche médicale, Nice, France.,Centre national de la recherche scientifique, Institut de Biologie Valrose, Nice, France
| | - Céline S Nicolas
- Institut de Biologie Valrose, University of Nice Sophia Antipolis, Nice, France.,Institut de Biologie Valrose, Institut national de la santé et de la recherche médicale, Nice, France.,Centre national de la recherche scientifique, Institut de Biologie Valrose, Nice, France
| | - Nikita Lukianets
- Institut de Biologie Valrose, University of Nice Sophia Antipolis, Nice, France.,Institut de Biologie Valrose, Institut national de la santé et de la recherche médicale, Nice, France.,Centre national de la recherche scientifique, Institut de Biologie Valrose, Nice, France
| | - Laura Frangeul
- Department of Basic Neurosciences, University of Geneva, Geneva, Switzerland
| | - Mariel Pietri
- Institut de Biologie Valrose, University of Nice Sophia Antipolis, Nice, France.,Institut de Biologie Valrose, Institut national de la santé et de la recherche médicale, Nice, France.,Centre national de la recherche scientifique, Institut de Biologie Valrose, Nice, France
| | - Tao Sun
- Department of Cell and Developmental Biology, Weill Medical College of Cornell University, New York, United States
| | - Guillaume Sandoz
- Institut de Biologie Valrose, University of Nice Sophia Antipolis, Nice, France.,Institut de Biologie Valrose, Institut national de la santé et de la recherche médicale, Nice, France.,Centre national de la recherche scientifique, Institut de Biologie Valrose, Nice, France
| | - Franck Grammont
- Institut de Biologie Valrose, University of Nice Sophia Antipolis, Nice, France.,Laboratoire J.A. Dieudonné, Nice, France
| | - Denis Jabaudon
- Department of Basic Neurosciences, University of Geneva, Geneva, Switzerland
| | - Michele Studer
- Institut de Biologie Valrose, University of Nice Sophia Antipolis, Nice, France.,Institut de Biologie Valrose, Institut national de la santé et de la recherche médicale, Nice, France.,Centre national de la recherche scientifique, Institut de Biologie Valrose, Nice, France
| | - Christian Alfano
- Institut de Biologie Valrose, University of Nice Sophia Antipolis, Nice, France.,Institut de Biologie Valrose, Institut national de la santé et de la recherche médicale, Nice, France.,Centre national de la recherche scientifique, Institut de Biologie Valrose, Nice, France
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93
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Tantirigama MLS, Oswald MJ, Clare AJ, Wicky HE, Day RC, Hughes SM, Empson RM. Fezf2 expression in layer 5 projection neurons of mature mouse motor cortex. J Comp Neurol 2015; 524:829-45. [PMID: 26234885 DOI: 10.1002/cne.23875] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Revised: 07/29/2015] [Accepted: 07/30/2015] [Indexed: 12/24/2022]
Abstract
The mature cerebral cortex contains a wide diversity of neuron phenotypes. This diversity is specified during development by neuron-specific expression of key transcription factors, some of which are retained for the life of the animal. One of these key developmental transcription factors that is also retained in the adult is Fezf2, but the neuron types expressing it in the mature cortex are unknown. With a validated Fezf2-Gfp reporter mouse, whole-cell electrophysiology with morphology reconstruction, cluster analysis, in vivo retrograde labeling, and immunohistochemistry, we identify a heterogeneous population of Fezf2(+) neurons in both layer 5A and layer 5B of the mature motor cortex. Functional electrophysiology identified two distinct subtypes of Fezf2(+) neurons that resembled pyramidal tract projection neurons (PT-PNs) and intratelencephalic projection neurons (IT-PNs). Retrograde labeling confirmed the former type to include corticospinal projection neurons (CSpPNs) and corticothalamic projection neurons (CThPNs), whereas the latter type included crossed corticostriatal projection neurons (cCStrPNs) and crossed-corticocortical projection neurons (cCCPNs). The two Fezf2(+) subtypes expressed either CTIP2 or SATB2 to distinguish their physiological identity and confirmed that specific expression combinations of key transcription factors persist in the mature motor cortex. Our findings indicate a wider role for Fezf2 within gene expression networks that underpin the diversity of layer 5 cortical projection neurons.
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Affiliation(s)
- Malinda L S Tantirigama
- Department of Physiology, Brain Health Research Centre, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand, 9054
| | - Manfred J Oswald
- Department of Physiology, Brain Health Research Centre, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand, 9054
| | - Alison J Clare
- Department of Biochemistry, Brain Health Research Centre, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand, 9054
| | - Hollie E Wicky
- Department of Biochemistry, Brain Health Research Centre, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand, 9054
| | - Robert C Day
- Department of Biochemistry, Brain Health Research Centre, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand, 9054
| | - Stephanie M Hughes
- Department of Biochemistry, Brain Health Research Centre, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand, 9054
| | - Ruth M Empson
- Department of Physiology, Brain Health Research Centre, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand, 9054
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94
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Ferreira AN, Yousuf H, Dalton S, Sheets PL. Highly differentiated cellular and circuit properties of infralimbic pyramidal neurons projecting to the periaqueductal gray and amygdala. Front Cell Neurosci 2015; 9:161. [PMID: 25972785 PMCID: PMC4412064 DOI: 10.3389/fncel.2015.00161] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 04/11/2015] [Indexed: 01/24/2023] Open
Abstract
The infralimbic (IL) cortex is a key node in an inter-connected network involved in fear and emotion processing. The cellular and circuit-level mechanisms whereby IL neurons receive, filter, and modulate incoming signals they project onward to diverse downstream nodes in this complex network remain poorly understood. Using the mouse as our model, we applied anatomical labeling strategies, brain slice electrophysiology, and focal activation of caged glutamate via laser scanning photostimulation (glu-LSPS) for quantitative neurophysiological analysis of projectionally defined neurons in IL. Injection of retrograde tracers into the periaqueductal gray (PAG) and basolateral amygdala (BLA) was used to identify cortico-PAG (CP) and cortico-BLA (CA) neurons in IL. CP neurons were found exclusively in layer 5 (L5) of IL whereas CA neurons were detected throughout layer 2, 3, and 5 of IL. We also identified a small percentage of IL neurons that project to both the PAG and the BLA. We found that L5 CP neurons have a more extensive dendritic structure compared to L5 CA neurons. Neurophysiological recordings performed on retrogradely labeled neurons in acute brain slice showed that CP and CA neurons in IL could be broadly classified in two groups: neuronal resonators and non-resonators. Layer 2 CA neurons were the only class that was exclusively non-resonating. CP, CA, and CP/CA neurons in layers 3 and 5 of IL consisted of heterogeneous populations of resonators and non-resonators showing that projection target is not an exclusive predictor of intrinsic physiology. Circuit mapping using glu-LSPS revealed that the strength and organization of local excitatory and inhibitory inputs were stronger to CP compared to CA neurons in IL. Together, our results establish an organizational scheme linking cellular neurophysiology with microcircuit parameters of defined neuronal subclasses in IL that send descending commands to subcortical structures involved in fear behavior.
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Affiliation(s)
- Ashley N Ferreira
- Department of Biological Sciences, University of Notre Dame Notre Dame, IN, USA
| | - Hanna Yousuf
- Department of Pharmacology and Toxicology, Indiana University School of Medicine-South Bend South Bend, IN, USA
| | - Sarah Dalton
- Department of Biological Sciences, University of Notre Dame Notre Dame, IN, USA
| | - Patrick L Sheets
- Department of Biological Sciences, University of Notre Dame Notre Dame, IN, USA ; Department of Pharmacology and Toxicology, Indiana University School of Medicine-South Bend South Bend, IN, USA
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95
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Chimeric rabies SADB19-VSVg-pseudotyped lentiviral vectors mediate long-range retrograde transduction from the mouse spinal cord. Gene Ther 2015; 22:357-64. [PMID: 25630949 DOI: 10.1038/gt.2015.3] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Revised: 12/08/2014] [Accepted: 12/30/2014] [Indexed: 12/21/2022]
Abstract
Lentiviral vectors have proved an effective method to deliver transgenes into the brain; however, they are often hampered by a lack of spread from the site of injection. Modifying the viral envelope with a portion of a rabies envelope glycoprotein can enhance spread in the brain by using long-range axon projections to facilitate retrograde transport. In this study, we generated two chimeric envelopes containing the extra-virion and transmembrane domain of rabies SADB19 or CVS-N2c with the intra-virion domain of vesicular stomatitis virus. Viral particles were packaged containing a green fluorescent protein reporter construct under the control of the phosphoglycerokinase promoter. Both vectors produced high-titer particles with successful integration of the glycoproteins into the particle envelope and significant transduction of neurons in vitro. Injection of the SADB19 chimeric viral vector into the lumbar spinal cord of adult mice mediated a strong preference for gene transfer to local neurons and axonal terminals, with retrograde transport to neurons in the brainstem, hypothalamus and cerebral cortex. Development of this vector provides a useful means to reliably target select populations of neurons by retrograde targeting.
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96
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Saba L, Viscomi MT, Caioli S, Pignataro A, Bisicchia E, Pieri M, Molinari M, Ammassari-Teule M, Zona C. Altered Functionality, Morphology, and Vesicular Glutamate Transporter Expression of Cortical Motor Neurons from a Presymptomatic Mouse Model of Amyotrophic Lateral Sclerosis. Cereb Cortex 2015; 26:1512-28. [DOI: 10.1093/cercor/bhu317] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
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97
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Oxidative stress induced by cumene hydroperoxide evokes changes in neuronal excitability of rat motor cortex neurons. Neuroscience 2015; 289:85-98. [PMID: 25592424 DOI: 10.1016/j.neuroscience.2014.12.055] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 12/30/2014] [Accepted: 12/31/2014] [Indexed: 01/12/2023]
Abstract
Oxidative stress and the production of reactive oxygen radicals play a key role in neuronal cell damage. This paper describes an in vitro study that explores the neuronal responses to oxidative stress focusing on changes in neuronal excitability and functional membrane properties. This study was carried out in pyramidal cells of the motor cortex by applying whole-cell patch-clamp techniques on brain slices from young adult rats. Oxygen-derived free radical formation was induced by bath application of 10μM cumene hydroperoxide (CH) for 30min. CH produced marked changes in the electrophysiological properties of neurons (n=30). Resting membrane potential became progressively depolarized, as well as depolarization voltage, with no variations in voltage threshold. Membrane resistance showed a biphasic behavior, increasing after 5min of drug exposure and then it started to decrease, even under control values, after 15 and 30min. At the same time, changes in membrane resistance produced compensatory variations in the rheobase. The amplitude of the action potentials diminished and the duration increased progressively over time. Some of the neurons under study also lost their ability to discharge action potentials in a repetitive way. Most of the neurons, however, kept their repetitive discharge even though their maximum frequency and gain decreased. Furthermore, cancelation of the repetitive firing discharge took place at intensities that decreased with time of exposure to CH, which resulted in a narrower working range. We can conclude that oxidative stress compromises both neuronal excitability and the capability of generating action potentials, and so this type of neuronal functional failure could precede the neuronal death characteristics of many neurodegenerative diseases.
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98
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Komulainen E, Zdrojewska J, Freemantle E, Mohammad H, Kulesskaya N, Deshpande P, Marchisella F, Mysore R, Hollos P, Michelsen KA, Mågard M, Rauvala H, James P, Coffey ET. JNK1 controls dendritic field size in L2/3 and L5 of the motor cortex, constrains soma size, and influences fine motor coordination. Front Cell Neurosci 2014; 8:272. [PMID: 25309320 PMCID: PMC4162472 DOI: 10.3389/fncel.2014.00272] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Accepted: 08/20/2014] [Indexed: 11/23/2022] Open
Abstract
Genetic anomalies on the JNK pathway confer susceptibility to autism spectrum disorders, schizophrenia, and intellectual disability. The mechanism whereby a gain or loss of function in JNK signaling predisposes to these prevalent dendrite disorders, with associated motor dysfunction, remains unclear. Here we find that JNK1 regulates the dendritic field of L2/3 and L5 pyramidal neurons of the mouse motor cortex (M1), the main excitatory pathway controlling voluntary movement. In Jnk1-/- mice, basal dendrite branching of L5 pyramidal neurons is increased in M1, as is cell soma size, whereas in L2/3, dendritic arborization is decreased. We show that JNK1 phosphorylates rat HMW-MAP2 on T1619, T1622, and T1625 (Uniprot P15146) corresponding to mouse T1617, T1620, T1623, to create a binding motif, that is critical for MAP2 interaction with and stabilization of microtubules, and dendrite growth control. Targeted expression in M1 of GFP-HMW-MAP2 that is pseudo-phosphorylated on T1619, T1622, and T1625 increases dendrite complexity in L2/3 indicating that JNK1 phosphorylation of HMW-MAP2 regulates the dendritic field. Consistent with the morphological changes observed in L2/3 and L5, Jnk1-/- mice exhibit deficits in limb placement and motor coordination, while stride length is reduced in older animals. In summary, JNK1 phosphorylates HMW-MAP2 to increase its stabilization of microtubules while at the same time controlling dendritic fields in the main excitatory pathway of M1. Moreover, JNK1 contributes to normal functioning of fine motor coordination. We report for the first time, a quantitative Sholl analysis of dendrite architecture, and of motor behavior in Jnk1-/- mice. Our results illustrate the molecular and behavioral consequences of interrupted JNK1 signaling and provide new ground for mechanistic understanding of those prevalent neuropyschiatric disorders where genetic disruption of the JNK pathway is central.
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Affiliation(s)
- Emilia Komulainen
- Turku Centre for Biotechnology, Åbo Akademi University and University of Turku Turku, Finland
| | - Justyna Zdrojewska
- Turku Centre for Biotechnology, Åbo Akademi University and University of Turku Turku, Finland
| | - Erika Freemantle
- Turku Centre for Biotechnology, Åbo Akademi University and University of Turku Turku, Finland
| | - Hasan Mohammad
- Turku Centre for Biotechnology, Åbo Akademi University and University of Turku Turku, Finland
| | | | - Prasannakumar Deshpande
- Turku Centre for Biotechnology, Åbo Akademi University and University of Turku Turku, Finland
| | - Francesca Marchisella
- Turku Centre for Biotechnology, Åbo Akademi University and University of Turku Turku, Finland
| | - Raghavendra Mysore
- Turku Centre for Biotechnology, Åbo Akademi University and University of Turku Turku, Finland
| | - Patrik Hollos
- Turku Centre for Biotechnology, Åbo Akademi University and University of Turku Turku, Finland
| | | | - Mats Mågard
- Institute for Immune Technology, Medicon Village, University of Lund Lund, Sweden
| | - Heikki Rauvala
- Neuroscience Center, University of Helsinki Helsinki, Finland
| | - Peter James
- Institute for Immune Technology, Medicon Village, University of Lund Lund, Sweden
| | - Eleanor T Coffey
- Turku Centre for Biotechnology, Åbo Akademi University and University of Turku Turku, Finland
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Expression of the developmental transcription factor Fezf2 identifies a distinct subpopulation of layer 5 intratelencephalic-projection neurons in mature mouse motor cortex. J Neurosci 2014; 34:4303-8. [PMID: 24647950 DOI: 10.1523/jneurosci.3111-13.2014] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The transcription factor encoded by Fez family zinc finger 2 (Fezf2) is necessary for normal development of the cerebral cortex. However, Fezf2 continues to be expressed in the mature brain, indicating that it might also be necessary for cortical function throughout life. Here, we show a unique identity of Fezf2-expressing intratelencephalic-projection neurons (IT-PNs) in layer 5 of the mature mouse motor cortex, using a Fezf2-Gfp reporter mouse, in vivo retrograde labeling, whole-cell electrophysiology with morphology reconstruction, and cluster analysis. Fezf2-expressing IT-PNs occupy layer 5A and display an apical dendritic tuft; functionally, they fire broad, adapting action potentials and exhibit an Ih-mediated voltage sag that influences their synaptic properties. In contrast, IT-PNs without Fezf2 expression mainly occupy layer 5B, do not display a tuft, and exhibit regular action potential firing and little sag. Both groups of IT-PNs demonstrated distinct frequency-selective synaptic responses to commissural inputs, indicating unique contributions within the cortical microcircuitry. Our findings establish a new, distinct physiological identity of Fezf2-expressing neurons within mature motor cortex.
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