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Taub DG, Jiang Q, Pietrafesa F, Su J, Carroll A, Greene C, Blanchard MR, Jain A, El-Rifai M, Callen A, Yager K, Chung C, He Z, Chen C, Woolf CJ. The secondary somatosensory cortex gates mechanical and heat sensitivity. Nat Commun 2024; 15:1289. [PMID: 38346995 PMCID: PMC10861531 DOI: 10.1038/s41467-024-45729-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 02/01/2024] [Indexed: 02/15/2024] Open
Abstract
The cerebral cortex is vital for the processing and perception of sensory stimuli. In the somatosensory axis, information is received primarily by two distinct regions, the primary (S1) and secondary (S2) somatosensory cortices. Top-down circuits stemming from S1 can modulate mechanical and cooling but not heat stimuli such that circuit inhibition causes blunted perception. This suggests that responsiveness to particular somatosensory stimuli occurs in a modality specific fashion and we sought to determine additional cortical substrates. In this work, we identify in a mouse model that inhibition of S2 output increases mechanical and heat, but not cooling sensitivity, in contrast to S1. Combining 2-photon anatomical reconstruction with chemogenetic inhibition of specific S2 circuits, we discover that S2 projections to the secondary motor cortex (M2) govern mechanical and heat sensitivity without affecting motor performance or anxiety. Taken together, we show that S2 is an essential cortical structure that governs mechanical and heat sensitivity.
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Affiliation(s)
- Daniel G Taub
- F. M. Kirby Neurobiology Center and Department of Neurology, Boston Children's Hospital, Boston, MA, USA
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Qiufen Jiang
- F. M. Kirby Neurobiology Center and Department of Neurology, Boston Children's Hospital, Boston, MA, USA
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Francesca Pietrafesa
- F. M. Kirby Neurobiology Center and Department of Neurology, Boston Children's Hospital, Boston, MA, USA
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Junfeng Su
- F. M. Kirby Neurobiology Center and Department of Neurology, Boston Children's Hospital, Boston, MA, USA
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Aloe Carroll
- College of Sciences, Northeastern University, Boston, MA, USA
| | - Caitlin Greene
- F. M. Kirby Neurobiology Center and Department of Neurology, Boston Children's Hospital, Boston, MA, USA
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | | | - Aakanksha Jain
- F. M. Kirby Neurobiology Center and Department of Neurology, Boston Children's Hospital, Boston, MA, USA
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Mahmoud El-Rifai
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Alexis Callen
- Morrissey College of Arts and Sciences, Boston College, Chestnut Hill, MA, USA
| | - Katherine Yager
- Morrissey College of Arts and Sciences, Boston College, Chestnut Hill, MA, USA
| | - Clara Chung
- Department of Neuroscience, Boston University, Boston, MA, USA
| | - Zhigang He
- F. M. Kirby Neurobiology Center and Department of Neurology, Boston Children's Hospital, Boston, MA, USA
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Chinfei Chen
- F. M. Kirby Neurobiology Center and Department of Neurology, Boston Children's Hospital, Boston, MA, USA
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Clifford J Woolf
- F. M. Kirby Neurobiology Center and Department of Neurology, Boston Children's Hospital, Boston, MA, USA.
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA.
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Gulledge AT. Cholinergic Activation of Corticofugal Circuits in the Adult Mouse Prefrontal Cortex. J Neurosci 2024; 44:e1388232023. [PMID: 38050146 PMCID: PMC10860659 DOI: 10.1523/jneurosci.1388-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 10/10/2023] [Accepted: 11/08/2023] [Indexed: 12/06/2023] Open
Abstract
Acetylcholine (ACh) promotes neocortical output to the thalamus and brainstem by preferentially enhancing the postsynaptic excitability of layer 5 pyramidal tract (PT) neurons relative to neighboring intratelencephalic (IT) neurons. Less is known about how ACh regulates the excitatory synaptic drive of IT and PT neurons. To address this question, spontaneous excitatory postsynaptic potentials (sEPSPs) were recorded in dual recordings of IT and PT neurons in slices of prelimbic cortex from adult female and male mice. ACh (20 µM) enhanced sEPSP amplitudes, frequencies, rise-times, and half-widths preferentially in PT neurons. These effects were blocked by the muscarinic receptor antagonist atropine (1 µM). When challenged with pirenzepine (1 µM), an antagonist selective for M1-type muscarinic receptors, ACh instead reduced sEPSP frequencies, suggesting that ACh may generally suppress synaptic transmission in the cortex via non-M1 receptors. Cholinergic enhancement of sEPSPs in PT neurons was not sensitive to antagonism of GABA receptors with gabazine (10 µM) and CGP52432 (2.5 µM) but was blocked by tetrodotoxin (1 µM), suggesting that ACh enhances action-potential-dependent excitatory synaptic transmission in PT neurons. ACh also preferentially promoted the occurrence of synchronous sEPSPs in dual recordings of PT neurons relative to IT-PT and IT-IT parings. Finally, selective chemogenetic silencing of hM4Di-expressing PT, but not commissural IT, neurons blocked cholinergic enhancement of sEPSP amplitudes and frequencies in PT neurons. These data suggest that, in addition to selectively enhancing the postsynaptic excitability of PT neurons, M1 receptor activation promotes corticofugal output by amplifying recurrent excitation within networks of PT neurons.
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Affiliation(s)
- Allan T Gulledge
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth College, Hanover 03755, New Hampshire
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3
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Gulledge AT. Cholinergic activation of corticofugal circuits in the adult mouse prefrontal cortex. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.28.538437. [PMID: 37163128 PMCID: PMC10168390 DOI: 10.1101/2023.04.28.538437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
In layer 5 of the neocortex, ACh promotes cortical output to the thalamus and brainstem by preferentially enhancing the postsynaptic excitability of pyramidal tract (PT) neurons relative to neighboring intratelencephalic (IT) neurons. Less is known about how ACh regulates the excitatory synaptic drive of IT and PT neurons. To address this question, spontaneous excitatory postsynaptic potentials (sEPSPs) were recorded in pairs of IT and PT neurons in slices of prelimbic cortex from adult female and male mice. ACh (20 µM) enhanced sEPSP amplitudes, frequencies, rise-times, and half-widths preferentially in PT neurons. These effects were blocked by the muscarinic acetylcholine receptor antagonist atropine (1 µM). When challenged with pirenzepine (1 µM), an antagonist selective for M1-type muscarinic receptors, ACh instead reduced sEPSP frequencies. The cholinergic increase in sEPSP amplitudes and frequencies in PT neurons was not sensitive to blockade of GABAergic receptors with gabazine (10 µM) and CGP52432 (2.5 µM), but was blocked by tetrodotoxin (1 µM), suggesting that ACh enhances action-potential-dependent excitatory synaptic transmission in PT neurons. ACh also preferentially promoted the occurrence of synchronous sEPSPs in pairs of PT neurons relative to IT-PT and IT-IT pairs. Finally, selective chemogenetic silencing of hM4Di-expressing PT, but not IT, neurons with clozapine-N-oxide (5 µM) blocked cholinergic enhancement of sEPSP amplitudes and frequencies in PT neurons. These data suggest that, in addition to enhancing the postsynaptic excitability of PT neurons, M1 receptor activation promotes corticofugal output by preferentially amplifying recurrent excitation within networks of PT neurons.
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Affiliation(s)
- Allan T Gulledge
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth College 74 College Street, Vail 601, Hanover, New Hampshire 03755, USA
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Taub DG, Jiang Q, Pietrafesa F, Su J, Greene C, Blanchard MR, Jain A, El-Rifai M, Callen A, Yager K, Chung C, He Z, Chen C, Woolf CJ. The Secondary Somatosensory Cortex Gates Mechanical and Thermal Sensitivity. RESEARCH SQUARE 2023:rs.3.rs-2976953. [PMID: 37461707 PMCID: PMC10350168 DOI: 10.21203/rs.3.rs-2976953/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/23/2023]
Abstract
The cerebral cortex is vital for the perception and processing of sensory stimuli. In the somatosensory axis, information is received by two distinct regions, the primary (S1) and secondary (S2) somatosensory cortices. Top-down circuits stemming from S1 can modulate mechanical and cooling but not heat stimuli such that circuit inhibition causes blunted mechanical and cooling perception. Using optogenetics and chemogenetics, we find that in contrast to S1, an inhibition of S2 output increases mechanical and heat, but not cooling sensitivity. Combining 2-photon anatomical reconstruction with chemogenetic inhibition of specific S2 circuits, we discover that S2 projections to the secondary motor cortex (M2) govern mechanical and thermal sensitivity without affecting motor or cognitive function. This suggests that while S2, like S1, encodes specific sensory information, that S2 operates through quite distinct neural substrates to modulate responsiveness to particular somatosensory stimuli and that somatosensory cortical encoding occurs in a largely parallel fashion.
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Affiliation(s)
- Daniel G. Taub
- F. M. Kirby Neurobiology Center and Department of Neurology, Boston Children’s Hospital, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Qiufen Jiang
- F. M. Kirby Neurobiology Center and Department of Neurology, Boston Children’s Hospital, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Francesca Pietrafesa
- F. M. Kirby Neurobiology Center and Department of Neurology, Boston Children’s Hospital, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Junfeng Su
- F. M. Kirby Neurobiology Center and Department of Neurology, Boston Children’s Hospital, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Caitlin Greene
- F. M. Kirby Neurobiology Center and Department of Neurology, Boston Children’s Hospital, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
| | | | - Aakanksha Jain
- F. M. Kirby Neurobiology Center and Department of Neurology, Boston Children’s Hospital, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Mahmoud El-Rifai
- Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Alexis Callen
- Morrissey College of Arts and Sciences, Boston College, Chestnut Hill, MA, USA
| | - Katherine Yager
- Morrissey College of Arts and Sciences, Boston College, Chestnut Hill, MA, USA
| | - Clara Chung
- Department of Neuroscience, Boston University, Boston, MA, USA
| | - Zhigang He
- F. M. Kirby Neurobiology Center and Department of Neurology, Boston Children’s Hospital, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Chinfei Chen
- F. M. Kirby Neurobiology Center and Department of Neurology, Boston Children’s Hospital, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
| | - Clifford J. Woolf
- F. M. Kirby Neurobiology Center and Department of Neurology, Boston Children’s Hospital, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
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Taub DG, Jiang Q, Pietrafesa F, Su J, Greene C, Blanchard MR, Jain A, El-Rifai M, Callen A, Yager K, Chung C, He Z, Chen C, Woolf CJ. The Secondary Somatosensory Cortex Gates Mechanical and Thermal Sensitivity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.19.541449. [PMID: 37293011 PMCID: PMC10245795 DOI: 10.1101/2023.05.19.541449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The cerebral cortex is vital for the perception and processing of sensory stimuli. In the somatosensory axis, information is received by two distinct regions, the primary (S1) and secondary (S2) somatosensory cortices. Top-down circuits stemming from S1 can modulate mechanical and cooling but not heat stimuli such that circuit inhibition causes blunted mechanical and cooling perception. Using optogenetics and chemogenetics, we find that in contrast to S1, an inhibition of S2 output increases mechanical and heat, but not cooling sensitivity. Combining 2-photon anatomical reconstruction with chemogenetic inhibition of specific S2 circuits, we discover that S2 projections to the secondary motor cortex (M2) govern mechanical and thermal sensitivity without affecting motor or cognitive function. This suggests that while S2, like S1, encodes specific sensory information, that S2 operates through quite distinct neural substrates to modulate responsiveness to particular somatosensory stimuli and that somatosensory cortical encoding occurs in a largely parallel fashion.
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6
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Lopez-Virgen V, Macias M, Rodriguez-Moreno P, Olivares-Moreno R, de Lafuente V, Rojas-Piloni G. Motor cortex projections to red and pontine nuclei have distinct roles during movement in the mouse. Neurosci Lett 2023; 807:137280. [PMID: 37116574 DOI: 10.1016/j.neulet.2023.137280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 04/16/2023] [Accepted: 04/24/2023] [Indexed: 04/30/2023]
Abstract
Motor control largely depends on the deep layer 5 (L5) pyramidal neurons that project to subcortical structures. However, it is largely unknown if these neurons are functionally segregated with distinct roles in movement performance. Here, we analyzed mouse motor cortex L5 pyramidal neurons projecting to the red and pontine nuclei during movement preparation and execution. Using photometry to analyze the calcium activity of L5 pyramidal neurons projecting to the red nucleus and pons, we reveal that both types of neurons activate with different temporal dynamics. Optogenetic inhibition of either kind of projection differentially affects forelimb movement onset and execution in a lever press task, but only the activity of corticopontine neurons is significantly correlated with trial-by-trial variations in reaction time. The results indicate that cortical neurons projecting to the red and pontine nuclei contribute differently to sensorimotor integration, suggesting that L5 output neurons are functionally compartmentalized generating, in parallel, different downstream information.
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Affiliation(s)
- Veronica Lopez-Virgen
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus UNAM-Juriquilla, Querétaro, México
| | - Martin Macias
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus UNAM-Juriquilla, Querétaro, México
| | - Paola Rodriguez-Moreno
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus UNAM-Juriquilla, Querétaro, México
| | - Rafael Olivares-Moreno
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus UNAM-Juriquilla, Querétaro, México
| | - Victor de Lafuente
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus UNAM-Juriquilla, Querétaro, México
| | - Gerardo Rojas-Piloni
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus UNAM-Juriquilla, Querétaro, México.
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Lopez-Virgen V, Olivares-Moreno R, de Lafuente V, Concha L, Rojas-Piloni G. Different subtypes of motor cortex pyramidal tract neurons projects to red and pontine nuclei. Front Cell Neurosci 2022; 16:1073731. [PMID: 36605617 PMCID: PMC9807917 DOI: 10.3389/fncel.2022.1073731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 12/05/2022] [Indexed: 12/24/2022] Open
Abstract
Introduction Pyramidal tract neurons (PTNs) are fundamental elements for motor control. However, it is largely unknown if PTNs are segregated into different subtypes with distinct characteristics. Methods Using anatomical and electrophysiological tools, we analyzed in mice motor cortex PTNs projecting to red and pontine midbrain nuclei, which are important hubs connecting cerebral cortex and cerebellum playing a critical role in the regulation of movement. Results We reveal that the vast majority of M1 neurons projecting to the red and pontine nuclei constitutes different populations. Corticopontine neurons have higher conduction velocities and morphologically, a most homogeneous dendritic and spine distributions along cortical layers. Discussion The results indicate that cortical neurons projecting to the red and pontine nuclei constitute distinct anatomical and functional pathways which may contribute differently to sensorimotor integration.
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Macías M, Lopez-Virgen V, Olivares-Moreno R, Rojas-Piloni G. Corticospinal neurons from motor and somatosensory cortices exhibit different temporal activity dynamics during motor learning. Front Hum Neurosci 2022; 16:1043501. [PMID: 36504625 PMCID: PMC9732016 DOI: 10.3389/fnhum.2022.1043501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 11/10/2022] [Indexed: 11/27/2022] Open
Abstract
The ability to learn motor skills implicates an improvement in accuracy, speed and consistency of movements. Motor control is related to movement execution and involves corticospinal neurons (CSp), which are broadly distributed in layer 5B of the motor and somatosensory cortices. CSp neurons innervate the spinal cord and are functionally diverse. However, whether CSp activity differs between different cortical areas throughout motor learning has been poorly explored. Given the importance and interaction between primary motor (M1) and somatosensory (S1) cortices related to movement, we examined the functional roles of CSp neurons in both areas. We induced the expression of GCaMP7s calcium indicator to perform photometric calcium recordings from layer 5B CSp neurons simultaneously in M1 and S1 cortices and track their activity while adult mice learned and performed a cued lever-press task. We found that during early learning sessions, the population calcium activity of CSp neurons in both cortices during movement did not change significantly. In late learning sessions the peak amplitude and duration of calcium activity CSp neurons increased in both, M1 and S1 cortices. However, S1 and M1 CSp neurons display a different temporal dynamic during movements that occurred when animals learned the task; both M1 and S1 CSp neurons activate before movement initiation, however, M1 CSp neurons continue active during movement performance, reinforcing the idea of the diversity of the CSp system and suggesting that CSp neuron activity in M1 and S1 cortices throughout motor learning have different functional roles for sensorimotor integration.
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Corticospinal populations broadcast complex motor signals to coordinated spinal and striatal circuits. Nat Neurosci 2021; 24:1721-1732. [PMID: 34737448 PMCID: PMC8639707 DOI: 10.1038/s41593-021-00939-w] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 09/10/2021] [Indexed: 11/23/2022]
Abstract
Many models of motor control emphasize the role of sensorimotor cortex in movement, principally through the projections that corticospinal neurons (CSNs) make to the spinal cord. Additionally, CSNs possess expansive supraspinal axon collaterals, the functional organization of which is largely unknown. Using anatomical and electrophysiological circuit-mapping techniques in the mouse, we reveal dorsolateral striatum as the preeminent target of CSN collateral innervation. We found that this innervation is biased so that CSNs targeting different striatal pathways show biased targeting of spinal cord circuits. Contrary to more conventional perspectives, CSNs encode not only individual movements, but also information related to the onset and offset of motor sequences. Furthermore, similar activity patterns are broadcast by CSN populations targeting different striatal circuits. Our results reveal a logic of coordinated connectivity between forebrain and spinal circuits, where separate CSN modules broadcast similarly complex information to downstream circuits, suggesting that differences in postsynaptic connectivity dictate motor specificity.
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Harding EK, Fung SW, Bonin RP. Insights Into Spinal Dorsal Horn Circuit Function and Dysfunction Using Optical Approaches. Front Neural Circuits 2020; 14:31. [PMID: 32595458 PMCID: PMC7303281 DOI: 10.3389/fncir.2020.00031] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Accepted: 05/01/2020] [Indexed: 12/13/2022] Open
Abstract
Somatosensation encompasses a variety of essential modalities including touch, pressure, proprioception, temperature, pain, and itch. These peripheral sensations are crucial for all types of behaviors, ranging from social interaction to danger avoidance. Somatosensory information is transmitted from primary afferent fibers in the periphery into the central nervous system via the dorsal horn of the spinal cord. The dorsal horn functions as an intermediary processing center for this information, comprising a complex network of excitatory and inhibitory interneurons as well as projection neurons that transmit the processed somatosensory information from the spinal cord to the brain. It is now known that there can be dysfunction within this spinal cord circuitry in pathological pain conditions and that these perturbations contribute to the development and maintenance of pathological pain. However, the complex and heterogeneous network of the spinal dorsal horn has hampered efforts to further elucidate its role in somatosensory processing. Emerging optical techniques promise to illuminate the underlying organization and function of the dorsal horn and provide insights into the role of spinal cord sensory processing in shaping the behavioral response to somatosensory input that we ultimately observe. This review article will focus on recent advances in optogenetics and fluorescence imaging techniques in the spinal cord, encompassing findings from both in vivo and in vitro preparations. We will also discuss the current limitations and difficulties of employing these techniques to interrogate the spinal cord and current practices and approaches to overcome these challenges.
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Affiliation(s)
- Erika K Harding
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON, Canada.,Department of Comparative Biology and Experimental Medicine, University of Calgary, Calgary, AB, Canada
| | - Samuel Wanchi Fung
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON, Canada
| | - Robert P Bonin
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON, Canada.,University of Toronto Centre for the Study of Pain, University of Toronto, Toronto, ON, Canada
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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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