1
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Wang G, Wu W, Xu Y, Yang Z, Xiao B, Long L. Imaging Genetics in Epilepsy: Current Knowledge and New Perspectives. Front Mol Neurosci 2022; 15:891621. [PMID: 35706428 PMCID: PMC9189397 DOI: 10.3389/fnmol.2022.891621] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 05/06/2022] [Indexed: 12/11/2022] Open
Abstract
Epilepsy is a neurological network disease with genetics playing a much greater role than was previously appreciated. Unfortunately, the relationship between genetic basis and imaging phenotype is by no means simple. Imaging genetics integrates multidimensional datasets within a unified framework, providing a unique opportunity to pursue a global vision for epilepsy. This review delineates the current knowledge of underlying genetic mechanisms for brain networks in different epilepsy syndromes, particularly from a neural developmental perspective. Further, endophenotypes and their potential value are discussed. Finally, we highlight current challenges and provide perspectives for the future development of imaging genetics in epilepsy.
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Affiliation(s)
- Ge Wang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
- Clinical Research Center for Epileptic Disease of Hunan Province, Central South University, Changsha, China
| | - Wenyue Wu
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
- Department of Neurology, The Second Affiliated Hospital of Nanchang University, Jiangxi, China
| | - Yuchen Xu
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
- Department of Neurology, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Zhuanyi Yang
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
- Clinical Research Center for Epileptic Disease of Hunan Province, Central South University, Changsha, China
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China
| | - Bo Xiao
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
- Clinical Research Center for Epileptic Disease of Hunan Province, Central South University, Changsha, China
| | - Lili Long
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
- Clinical Research Center for Epileptic Disease of Hunan Province, Central South University, Changsha, China
- *Correspondence: Lili Long
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2
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Carriot J, McAllister G, Hooshangnejad H, Mackrous I, Cullen KE, Chacron MJ. Sensory adaptation mediates efficient and unambiguous encoding of natural stimuli by vestibular thalamocortical pathways. Nat Commun 2022; 13:2612. [PMID: 35551186 PMCID: PMC9098492 DOI: 10.1038/s41467-022-30348-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 04/26/2022] [Indexed: 11/09/2022] Open
Abstract
Sensory systems must continuously adapt to optimally encode stimuli encountered within the natural environment. The prevailing view is that such optimal coding comes at the cost of increased ambiguity, yet to date, prior studies have focused on artificial stimuli. Accordingly, here we investigated whether such a trade-off between optimality and ambiguity exists in the encoding of natural stimuli in the vestibular system. We recorded vestibular nuclei and their target vestibular thalamocortical neurons during naturalistic and artificial self-motion stimulation. Surprisingly, we found no trade-off between optimality and ambiguity. Using computational methods, we demonstrate that thalamocortical neural adaptation in the form of contrast gain control actually reduces coding ambiguity without compromising the optimality of coding under naturalistic but not artificial stimulation. Thus, taken together, our results challenge the common wisdom that adaptation leads to ambiguity and instead suggest an essential role in underlying unambiguous optimized encoding of natural stimuli.
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Affiliation(s)
- Jerome Carriot
- Department of Physiology, McGill University, Montréal, Canada
| | | | - Hamed Hooshangnejad
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, USA
| | | | - Kathleen E Cullen
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, USA.,Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, USA.,Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, USA.,Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, USA
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3
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Simko J, Markram H. Morphology, physiology and synaptic connectivity of local interneurons in the mouse somatosensory thalamus. J Physiol 2021; 599:5085-5101. [PMID: 34591324 PMCID: PMC9298088 DOI: 10.1113/jp281711] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 09/28/2021] [Indexed: 01/03/2023] Open
Abstract
Abstract The thalamic reticular nucleus (TRN) neurons, projecting across the external medullary lamina, have long been considered to be the only significant source of inhibition of the somatosensory ventral posterior (VP) nuclei of the thalamus. Here we report for the first time effective local inhibition and disinhibition in the VP. Inhibitory interneurons were found in GAD67–GFP‐expressing mice and studied using in vitro multiple patch clamp. Inhibitory interneurons have expansive bipolar or tripolar morphologies, reach across most of the VP nucleus and display low threshold bursting behaviour. They form triadic and non‐triadic synaptic connections onto thalamocortical relay neurons and other interneurons, mediating feedforward inhibition and disinhibition. Synaptic inputs arrive before those expected from the TRN neurons, suggesting that local inhibition plays an early and significant role in the functioning of the somatosensory thalamus.
![]() Key points The physiology and structure of local interneurons in the mouse somatosensory thalamus is described for the first time. Inhibitory interneurons have extensive dendritic arborization providing significant local dendro‐dendritic inhibition in the somatosensory thalamus. Triadic and non‐triadic synaptic connectivity onto thalamic relay neurons and other interneurons provides both local feedforward inhibition and disinhibition. Interneurons of the somatosensory thalamus provide inhibition before the thalamic reticular nucleus, suggesting they play an important role in sensory perception.
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Affiliation(s)
- Jane Simko
- Laboratory of Neural Microcircuitry, Brain Mind Institute, School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Henry Markram
- Laboratory of Neural Microcircuitry, Brain Mind Institute, School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.,Blue Brain Project, École Polytechnique Fédérale de Lausanne (EPFL), Campus Biotech, Geneva, Switzerland
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4
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Saavedra L, Wallace K, Freudenrich TF, Mall M, Mundy WR, Davila J, Shafer TJ, Wernig M, Haag D. Comparison of Acute Effects of Neurotoxic Compounds on Network Activity in Human and Rodent Neural Cultures. Toxicol Sci 2021; 180:295-312. [PMID: 33537736 DOI: 10.1093/toxsci/kfab008] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Assessment of neuroactive effects of chemicals in cell-based assays remains challenging as complex functional tissue is required for biologically relevant readouts. Recent in vitro models using rodent primary neural cultures grown on multielectrode arrays allow quantitative measurements of neural network activity suitable for neurotoxicity screening. However, robust systems for testing effects on network function in human neural models are still lacking. The increasing number of differentiation protocols for generating neurons from human-induced pluripotent stem cells (hiPSCs) holds great potential to overcome the unavailability of human primary tissue and expedite cell-based assays. Yet, the variability in neuronal activity, prolonged ontogeny and rather immature stage of most neuronal cells derived by standard differentiation techniques greatly limit their utility for screening neurotoxic effects on human neural networks. Here, we used excitatory and inhibitory neurons, separately generated by direct reprogramming from hiPSCs, together with primary human astrocytes to establish highly functional cultures with defined cell ratios. Such neuron/glia cocultures exhibited pronounced neuronal activity and robust formation of synchronized network activity on multielectrode arrays, albeit with noticeable delay compared with primary rat cortical cultures. We further investigated acute changes of network activity in human neuron/glia cocultures and rat primary cortical cultures in response to compounds with known adverse neuroactive effects, including gamma amino butyric acid receptor antagonists and multiple pesticides. Importantly, we observed largely corresponding concentration-dependent effects on multiple neural network activity metrics using both neural culture types. These results demonstrate the utility of directly converted neuronal cells from hiPSCs for functional neurotoxicity screening of environmental chemicals.
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Affiliation(s)
- Lorena Saavedra
- NeuCyte Inc., San Carlos, California 94070, USA.,Institute for Stem Cell Biology and Regenerative Medicine, Department of Pathology, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Kathleen Wallace
- BCTD, CCTE, ORD, US Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA
| | - Theresa F Freudenrich
- BCTD, CCTE, ORD, US Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA
| | - Moritz Mall
- Institute for Stem Cell Biology and Regenerative Medicine, Department of Pathology, Stanford University School of Medicine, Stanford, California 94305, USA.,Cell Fate Engineering and Disease Modeling Group, German Cancer Research Center (DKFZ) and DKFZ-ZMBH Alliance, Heidelberg 69120, Germany
| | - William R Mundy
- BCTD, CCTE, ORD, US Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA
| | - Jorge Davila
- NeuCyte Inc., San Carlos, California 94070, USA.,Institute for Stem Cell Biology and Regenerative Medicine, Department of Pathology, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Timothy J Shafer
- BCTD, CCTE, ORD, US Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA
| | - Marius Wernig
- Institute for Stem Cell Biology and Regenerative Medicine, Department of Pathology, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Daniel Haag
- NeuCyte Inc., San Carlos, California 94070, USA.,Institute for Stem Cell Biology and Regenerative Medicine, Department of Pathology, Stanford University School of Medicine, Stanford, California 94305, USA
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5
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Sampathkumar V, Miller-Hansen A, Sherman SM, Kasthuri N. Integration of signals from different cortical areas in higher order thalamic neurons. Proc Natl Acad Sci U S A 2021; 118:e2104137118. [PMID: 34282018 PMCID: PMC8325356 DOI: 10.1073/pnas.2104137118] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Higher order thalamic neurons receive driving inputs from cortical layer 5 and project back to the cortex, reflecting a transthalamic route for corticocortical communication. To determine whether or not individual neurons integrate signals from different cortical populations, we combined electron microscopy "connectomics" in mice with genetic labeling to disambiguate layer 5 synapses from somatosensory and motor cortices to the higher order thalamic posterior medial nucleus. A significant convergence of these inputs was found on 19 of 33 reconstructed thalamic cells, and as a population, the layer 5 synapses were larger and located more proximally on dendrites than were unlabeled synapses. Thus, many or most of these thalamic neurons do not simply relay afferent information but instead integrate signals as disparate in this case as those emanating from sensory and motor cortices. These findings add further depth and complexity to the role of the higher order thalamus in overall cortical functioning.
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Affiliation(s)
- Vandana Sampathkumar
- Department of Neurobiology, University of Chicago, Chicago, IL 60637
- Biosciences Division, Argonne National Laboratory, Lemont, IL 60439
| | | | - S Murray Sherman
- Department of Neurobiology, University of Chicago, Chicago, IL 60637;
| | - Narayanan Kasthuri
- Department of Neurobiology, University of Chicago, Chicago, IL 60637;
- Biosciences Division, Argonne National Laboratory, Lemont, IL 60439
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6
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O'Reilly C, Iavarone E, Yi J, Hill SL. Rodent somatosensory thalamocortical circuitry: Neurons, synapses, and connectivity. Neurosci Biobehav Rev 2021; 126:213-235. [PMID: 33766672 DOI: 10.1016/j.neubiorev.2021.03.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 02/15/2021] [Accepted: 03/14/2021] [Indexed: 01/21/2023]
Abstract
As our understanding of the thalamocortical system deepens, the questions we face become more complex. Their investigation requires the adoption of novel experimental approaches complemented with increasingly sophisticated computational modeling. In this review, we take stock of current data and knowledge about the circuitry of the somatosensory thalamocortical loop in rodents, discussing common principles across modalities and species whenever appropriate. We review the different levels of organization, including the cells, synapses, neuroanatomy, and network connectivity. We provide a complete overview of this system that should be accessible for newcomers to this field while nevertheless being comprehensive enough to serve as a reference for seasoned neuroscientists and computational modelers studying the thalamocortical system. We further highlight key gaps in data and knowledge that constitute pressing targets for future experimental work. Filling these gaps would provide invaluable information for systematically unveiling how this system supports behavioral and cognitive processes.
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Affiliation(s)
- Christian O'Reilly
- Azrieli Centre for Autism Research, Montreal Neurological Institute, McGill University, Montreal, Canada; Ronin Institute, Montclair, NJ, USA; Blue Brain Project, École Polytechnique Fédérale de Lausanne, Geneva, Switzerland.
| | - Elisabetta Iavarone
- Blue Brain Project, École Polytechnique Fédérale de Lausanne, Geneva, Switzerland
| | - Jane Yi
- Brain Mind Institute, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Sean L Hill
- Blue Brain Project, École Polytechnique Fédérale de Lausanne, Geneva, Switzerland; Department of Psychiatry, University of Toronto, Toronto, Canada; Centre for Addiction and Mental Health, Toronto, Canada.
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7
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Syed P, Durisic N, Harvey RJ, Sah P, Lynch JW. Effects of GABA A Receptor α3 Subunit Epilepsy Mutations on Inhibitory Synaptic Signaling. Front Mol Neurosci 2020; 13:602559. [PMID: 33328885 PMCID: PMC7714833 DOI: 10.3389/fnmol.2020.602559] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 10/02/2020] [Indexed: 11/13/2022] Open
Abstract
Missense mutations T166M, Q242L, T336M, and Y474C in the GABAA receptor (GABAAR) α3 subunit gene are associated with epileptic seizures, dysmorphic features, intellectual disability, and developmental delay. When incorporated into GABAARs expressed in oocytes, all mutations are known to reduce GABA-evoked whole-cell currents. However, their impact on the properties of inhibitory synaptic currents (IPSCs) is unknown, largely because it is difficult to establish, much less control, the stoichiometry of GABAAR expressed in native neuronal synapses. To circumvent this problem, we employed a HEK293 cell-neuron co-culture expression system that permits the recording of IPSCs mediated by a pure population of GABAARs with a defined stoichiometry. We first demonstrated that IPSCs mediated by α3-containing GABAARs (α3β3γ2) decay significantly slower than those mediated by α1-containing isoforms (α1β2γ2 or α1β3γ2). GABAAR α3 mutations did not affect IPSC peak amplitudes or 10-90% rise times, but three of the mutations affected IPSC decay. T336M significantly accelerated the IPSC decay rate whereas T166M and Y474C had the opposite effect. The acceleration of IPSC decay kinetics caused by the T366M mutation was returned to wild-type-like values by the anti-epileptic medication, midazolam. Quantification experiments in HEK293 cells revealed a significant reduction in cell-surface expression for all mutants, in agreement with previous oocyte data. Taken together, our results show that impaired surface expression and altered IPSC decay rates could both be significant factors underlying the pathologies associated with these mutations.
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Affiliation(s)
- Parnayan Syed
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Nela Durisic
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Robert J Harvey
- School of Health and Behavioural Sciences, University of the Sunshine Coast, Maroochydore, QLD, Australia.,Sunshine Coast Health Institute, Birtinya, QLD, Australia
| | - Pankaj Sah
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia.,Department of Biology, Joint Center for Neuroscience and Neural Engineering, Southern University of Science and Technology, Shenzhen, China
| | - Joseph W Lynch
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
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8
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Gabrieli D, Schumm SN, Vigilante NF, Parvesse B, Meaney DF. Neurodegeneration exposes firing rate dependent effects on oscillation dynamics in computational neural networks. PLoS One 2020; 15:e0234749. [PMID: 32966291 PMCID: PMC7510994 DOI: 10.1371/journal.pone.0234749] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 06/01/2020] [Indexed: 12/26/2022] Open
Abstract
Traumatic brain injury (TBI) can lead to neurodegeneration in the injured circuitry, either through primary structural damage to the neuron or secondary effects that disrupt key cellular processes. Moreover, traumatic injuries can preferentially impact subpopulations of neurons, but the functional network effects of these targeted degeneration profiles remain unclear. Although isolating the consequences of complex injury dynamics and long-term recovery of the circuit can be difficult to control experimentally, computational networks can be a powerful tool to analyze the consequences of injury. Here, we use the Izhikevich spiking neuron model to create networks representative of cortical tissue. After an initial settling period with spike-timing-dependent plasticity (STDP), networks developed rhythmic oscillations similar to those seen in vivo. As neurons were sequentially removed from the network, population activity rate and oscillation dynamics were significantly reduced. In a successive period of network restructuring with STDP, network activity levels returned to baseline for some injury levels and oscillation dynamics significantly improved. We next explored the role that specific neurons have in the creation and termination of oscillation dynamics. We determined that oscillations initiate from activation of low firing rate neurons with limited structural inputs. To terminate oscillations, high activity excitatory neurons with strong input connectivity activate downstream inhibitory circuitry. Finally, we confirm the excitatory neuron population role through targeted neurodegeneration. These results suggest targeted neurodegeneration can play a key role in the oscillation dynamics after injury.
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Affiliation(s)
- David Gabrieli
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Samantha N. Schumm
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Nicholas F. Vigilante
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Brandon Parvesse
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - David F. Meaney
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Department of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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9
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Arkan S, Kasap M, Akman Ö, Akpınar G, Ateş N, Karson A. The lower expression of parvalbumin in the primary somatosensory cortex of WAG/Rij rats may facilitate the occurrence of absence seizures. Neurosci Lett 2019; 709:134299. [DOI: 10.1016/j.neulet.2019.134299] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 05/12/2019] [Accepted: 05/27/2019] [Indexed: 12/29/2022]
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10
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Aksenov DP, Li L, Miller MJ, Wyrwicz AM. Role of the inhibitory system in shaping the BOLD fMRI response. Neuroimage 2019; 201:116034. [PMID: 31326573 DOI: 10.1016/j.neuroimage.2019.116034] [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: 02/11/2019] [Revised: 07/11/2019] [Accepted: 07/17/2019] [Indexed: 12/17/2022] Open
Abstract
The shape of the blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) signal can vary considerably even across structures of the same sensory pathway. Here, we characterized the temporal behavior of the stimulus-evoked BOLD response in the primary cortical and subcortical regions of the visual and somatosensory whisker systems in awake rabbits. Despite similar BOLD responses in the thalamic nuclei, considerable differences in shape and duration emerged between the sensory cortices. Whereas the BOLD response in the whisker barrel cortex (WBC) was non-adaptive, BOLD in the visual cortex (V1) showed adaptation similar to simultaneously-recorded LFP and single unit activity. Analysis of baseline neuronal activity revealed significantly lower firing rates in V1 vs. WBC. We hypothesized that these changes point to region-dependent differences in the inhibitory systems which shape the hemodynamic response in each structure. To test the effect of neuronal baseline level inhibition on the BOLD signal shape, we locally injected the GABAA agonist muscimol in WBC. Adaptation emerged in the BOLD response after injection, along with an overall decrease in baseline firing rate. These findings point to the importance of region-specific inhibitory shaping in determining the temporal behavior of the BOLD response in different brain areas.
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Affiliation(s)
| | - Limin Li
- NorthShore University HealthSystem, Evanston, IL, 60201, USA
| | | | - Alice M Wyrwicz
- NorthShore University HealthSystem, Evanston, IL, 60201, USA.
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11
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Dong P, Wang H, Shen XF, Jiang P, Zhu XT, Li Y, Gao JH, Lin S, Huang Y, He XB, Xu FQ, Duan S, Lian H, Wang H, Chen J, Li XM. A novel cortico-intrathalamic circuit for flight behavior. Nat Neurosci 2019; 22:941-949. [DOI: 10.1038/s41593-019-0391-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 03/19/2019] [Indexed: 11/09/2022]
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12
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Reid CA, Rollo B, Petrou S, Berkovic SF. Can mutation‐mediated effects occurring early in development cause long‐term seizure susceptibility in genetic generalized epilepsies? Epilepsia 2018; 59:915-922. [DOI: 10.1111/epi.14077] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/20/2018] [Indexed: 12/12/2022]
Affiliation(s)
- Christopher Alan Reid
- The Florey Institute for Neuroscience and Mental Health The University of Melbourne Parkville Victoria Australia
| | - Ben Rollo
- The Florey Institute for Neuroscience and Mental Health The University of Melbourne Parkville Victoria Australia
| | - Steven Petrou
- The Florey Institute for Neuroscience and Mental Health The University of Melbourne Parkville Victoria Australia
| | - Samuel F. Berkovic
- Department of Medicine Epilepsy Research Centre Austin Health University of Melbourne Heidelberg Victoria Australia
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13
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Bombardi C, Venzi M, Crunelli V, Di Giovanni G. Developmental changes of GABA immunoreactivity in cortico-thalamic networks of an absence seizure model. Neuropharmacology 2018; 136:56-67. [PMID: 29471054 PMCID: PMC6018618 DOI: 10.1016/j.neuropharm.2018.01.047] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 01/09/2018] [Accepted: 01/29/2018] [Indexed: 12/24/2022]
Abstract
Absence seizures (ASs) are associated with abnormalities in gamma-aminobutyric acid (GABA) neurotransmission in the thalamus and the cortex. In the present study, we used light microscopy GABA immunocytochemistry to quantify the GABA-immunoreactive (GABA-IR) neurons and neuropil in the thalamic ventral basal (VB) nucleus, the nucleus reticularis thalami (NRT), the dorsal lateral geniculate (dLGN), the primary motor cortex (M1) and perioral region of the somatosensory cortex (S1po) of genetic absence epilepsy rats from Strasbourg (GAERS). We used both the relative non-epileptic control (NEC) and normal Wistar rats as control strains, and investigated GABA immunostaining at postnatal day 15 (P15), P25, and P90. The main findings were i) an increase in GABA-IR neuropil in the VB at P25 and P90 in GAERS but not in NEC and Wistar rats; ii) an increase in NRT GABA-IR neurons in GAERS and NEC, but not Wistar, rats at both P25 and P90; and iii) an increase in GABA-IR neuron density in S1po of GAERS at P25 and P90 and in Wistar at P90. These results indicate that the increased GABAergic innervation in the VB at P25 most likely contributes to the enhanced tonic inhibition observed in GAERS prior to AS onset, whereas the lack of any anatomo-morphological GABAergic differences in GAERS S1po suggests that functional more than structural abnormalities underlie the origin of cortical paroxysms in S1po of this AS model. This article is part of the “Special Issue Dedicated to Norman G. Bowery”. GABA-IR profiles increase in P25 to P90 VB neuropil in GAERS but not in NEC and Wistar rats. NRT GABA-IR neurons increase in P25 and P90 GAERS and NEC, but not in Wistar rats. GABA-IR neuron density increases in S1po of GAERS at P25 and P90 and in Wistar at P90.
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Affiliation(s)
- Cristiano Bombardi
- University of Bologna, Department of Veterinary Medical Science, Bologna, Italy
| | - Marcello Venzi
- Neuroscience Division, School of Bioscience, Cardiff University, Museum Avenue, Cardiff CF10 3AX, UK
| | - Vincenzo Crunelli
- Neuroscience Division, School of Bioscience, Cardiff University, Museum Avenue, Cardiff CF10 3AX, UK; Department of Physiology and Biochemistry, University of Malta, Malta.
| | - Giuseppe Di Giovanni
- Neuroscience Division, School of Bioscience, Cardiff University, Museum Avenue, Cardiff CF10 3AX, UK; Department of Physiology and Biochemistry, University of Malta, Malta.
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14
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Leresche N, Lambert RC. GABA receptors and T-type Ca 2+ channels crosstalk in thalamic networks. Neuropharmacology 2017; 136:37-45. [PMID: 28601398 DOI: 10.1016/j.neuropharm.2017.06.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 06/01/2017] [Accepted: 06/06/2017] [Indexed: 10/19/2022]
Abstract
Although the thalamus presents a rather limited repertoire of GABAergic cell types compare to other CNS area, this structure is a privileged system to study how GABA impacts neuronal network excitability. Indeed both glutamatergic thalamocortical (TC) and GABAergic nucleus reticularis thalami (NRT) neurons present a high expression of T-type voltage-dependent Ca2+ channels whose activation that shapes the output of the thalamus critically depends upon a preceding hyperpolarisation. Because of this strict dependence, a tight functional link between GABA mediated hyperpolarization and T-currents characterizes the thalamic network excitability. In this review we summarize a number of studies showing that the relationships between the various thalamic GABAA/B receptors and T-channels are complex and bidirectional. We discuss how this dynamic interaction sets the global intrathalamic network activity and its long-term plasticity and highlight how the functional relationship between GABA release and T-channel-dependent excitability is finely tuned by the T-channel activation itself. Finally, we illustrate how an impaired balance between T-channels and GABA receptors can lead to pathologically abnormal cellular and network behaviours. This article is part of the "Special Issue Dedicated to Norman G. Bowery".
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Affiliation(s)
- Nathalie Leresche
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005 Paris, France.
| | - Régis C Lambert
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005 Paris, France
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15
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Kirazlı Ö, Çavdar S, Yıldızel S, Onat F, Kaptanoğlu E. A developmental study of glutamatergic neuron populations in the ventrobasal and the lateral geniculate nucleus of the thalamus: Comparing Genetic Absence Rats from Strasbourg (GAERS) and normal control wistar rats. Int J Dev Neurosci 2016; 56:35-41. [PMID: 27939427 DOI: 10.1016/j.ijdevneu.2016.12.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 12/04/2016] [Indexed: 11/28/2022] Open
Abstract
An imbalance of GABAergic inhibition and glutamatergic excitation is suspected to be the cause of absence epileptic seizures. Absence seizures are known to be generated in thalamocortical circuitry. In the present study we used light microscopy immunohistochemistry to quantify the density of glutamate+ve neurons at two developmental stages (P10 and P60) in two thalamic nuclei, the ventrobasal (VB) and lateral geniculate nucleus (LGN) in Wistar rats and compared the results with similar data obtained from genetic absence epilepsy rats from Strasbourg (GAERS). Rats were perfused transcardially with glutaraldehyde and paraformaldehyde fixative, then samples from VB and LGN were removed from each animal and sectioned. The glutamatergic neurons were labelled using light-microscopic glutamate immunohistochemistry. The disector method was used to quantify the glutamate+ve neurons in VB and LGN of GAERS and Wistar rats. The data were statistically analyzed. The distribution of the glutamate+ve neurons in the VB thalamic nucleus showed a significant reduction in the neuronal profiles per unit thalamic area from P10 to P60 in both Wistar and GAERS. The decrease was greater in the GAERS compared to the Wistar animals. However, in the LGN no reduction was observed either in the Wistar or in the GAERS. Comparing the density of glutamate+ve neurons in the VB thalamic nucleus of P10 of Wistar animals with of P10 GAERS showed statistically significant greater densities of these neurons in GAERS than in the Wistar rats. However no significant difference was present at P60 between the Wistar and GAERS animals. The disproportional decrease in GAERS may be related to the onset of absence seizures or may be related to neurogenesis of absence epilepsy.
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Affiliation(s)
- Özlem Kirazlı
- Department of Anatomy, School of Medicine, Marmara University, Istanbul, Turkey
| | - Safiye Çavdar
- Department of Anatomy, School of Medicine, Koç University, Rumelifeneri Yolu Sarıyer, Istanbul, Turkey.
| | - Sercan Yıldızel
- Department of Anatomy, School of Medicine, Marmara University, Istanbul, Turkey
| | - Filiz Onat
- Department of Pharmacology, School of Medicine, Marmara University, Istanbul, Turkey
| | - Erkan Kaptanoğlu
- Department of Neurosurgery, Marmara University, School of Medicine, Institute of Neurological Sciences, Istanbul, Turkey
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Çavdar S, Özgür M, Kirazlı Ö, Karahüseyinoğlu S, Onat F. Comparing glutamatergic neuron population in the mediodorsal thalamic nucleus of genetic absence epilepsy rats from strasbourg (GAERS) and normal control Wistar rats. J Chem Neuroanat 2016; 77:93-99. [PMID: 27262783 DOI: 10.1016/j.jchemneu.2016.05.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 05/30/2016] [Accepted: 05/30/2016] [Indexed: 11/17/2022]
Abstract
An imbalance between GABAergic inhibition and glutamatergic excitation is suspected to play a role in the genesis of epileptic processes. In the present study we quantified the number of glutamate+ve neurons in the mediodorsal thalamic nucleus (MD) of genetic absence epilepsy rats from Strasbourg (GAERS) and compared these with values for normal Wistar rats. The MD thalamic nucleus was removed from each animal and the glutamatergic neurons were labelled using light-microscopy glutamate immunohistochemistry. The disector method was used to quantify the glutamate+ve neurons in the MD thalamic nucleus of GAERS and Wistar rats. The data were statistically analyzed. In the Wistar animals glutamate+ve neurons formed 89% and in GAERS 92.3% of the total neurons in 1000μm3 of MD thalamic nucleus. In GAERS glutamate+ve neurons showed statistically significant increase in the MD thalamic nucleus compared to Wistar animals. In Wistar animals the glutamate-ve neurons formed 11% and in GAERS 7.7% of the total neurons in 1000μm3 of MD thalamic. No significant difference was observed in glutamate-ve neurons between the two strains. The average diameter of glutamate+ve neurons showed no significance, while glutamate-ve neurons were significant between the two strains. The results of the present study, on genetic absence epilepsy model, GAERS, confirms the role of MD thalamic nucleus in chemically induced absence epilepsy.
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Affiliation(s)
- Safiye Çavdar
- Department of Anatomy, School of Medicine, Koç University, Sarıyer, Istanbul, Turkey.
| | - Merve Özgür
- Department of Anatomy, School of Medicine, Koç University, Sarıyer, Istanbul, Turkey
| | - Özlem Kirazlı
- Department of Anatomy, School of Medicine, Marmara University, Istanbul, Turkey
| | - Serçin Karahüseyinoğlu
- Department of Histology-Embryology, School of Medicine, Koç University, Sarıyer, Istanbul, Turkey
| | - Filiz Onat
- Department of Pharmacology and Clinic Pharmacology, School of Medicine, Marmara University, Istanbul, Turkey
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