1
|
Nano PR, Bhaduri A. Evaluation of advances in cortical development using model systems. Dev Neurobiol 2022; 82:408-427. [PMID: 35644985 PMCID: PMC10924780 DOI: 10.1002/dneu.22879] [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: 01/05/2022] [Revised: 04/26/2022] [Accepted: 04/30/2022] [Indexed: 11/11/2022]
Abstract
Compared with that of even the closest primates, the human cortex displays a high degree of specialization and expansion that largely emerges developmentally. Although decades of research in the mouse and other model systems has revealed core tenets of cortical development that are well preserved across mammalian species, small deviations in transcription factor expression, novel cell types in primates and/or humans, and unique cortical architecture distinguish the human cortex. Importantly, many of the genes and signaling pathways thought to drive human-specific cortical expansion also leave the brain vulnerable to disease, as the misregulation of these factors is highly correlated with neurodevelopmental and neuropsychiatric disorders. However, creating a comprehensive understanding of human-specific cognition and disease remains challenging. Here, we review key stages of cortical development and highlight known or possible differences between model systems and the developing human brain. By identifying the developmental trajectories that may facilitate uniquely human traits, we highlight open questions in need of approaches to examine these processes in a human context and reveal translatable insights into human developmental disorders.
Collapse
Affiliation(s)
- Patricia R Nano
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, USA
| | - Aparna Bhaduri
- Department of Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, USA
| |
Collapse
|
2
|
Del Rio-Bermudez C, Blumberg MS. Sleep as a window on the sensorimotor foundations of the developing hippocampus. Hippocampus 2022; 32:89-97. [PMID: 33945190 PMCID: PMC9118132 DOI: 10.1002/hipo.23334] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 03/21/2021] [Indexed: 02/03/2023]
Abstract
The hippocampal formation plays established roles in learning, memory, and related cognitive functions. Recent findings also suggest that the hippocampus integrates sensory feedback from self-generated movements to modulate ongoing motor responses in a changing environment. Such findings support the view of Bland and Oddie (Behavioural Brain Research, 2001, 127, 119-136) that the hippocampus is a site of sensorimotor integration. In further support of this view, we review neurophysiological evidence in developing rats that hippocampal function is built on a sensorimotor foundation and that this foundation is especially evident early in development. Moreover, at those ages when the hippocampus is first establishing functional connectivity with distant sensory and motor structures, that connectivity is preferentially expressed during periods of active (or REM) sleep. These findings reinforce the notion that sleep, as the predominant state of early infancy, provides a critical context for sensorimotor development, including development of the hippocampus and its associated network.
Collapse
Affiliation(s)
| | - Mark S Blumberg
- Department of Psychological and Brain Sciences, University of Iowa, Iowa City, Iowa, USA.,Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa, USA
| |
Collapse
|
3
|
Meng X, Solarana K, Bowen Z, Liu J, Nagode DA, Sheikh A, Winkowski DE, Kao JPY, Kanold PO. Transient Subgranular Hyperconnectivity to L2/3 and Enhanced Pairwise Correlations During the Critical Period in the Mouse Auditory Cortex. Cereb Cortex 2021; 30:1914-1930. [PMID: 31667495 DOI: 10.1093/cercor/bhz213] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 08/20/2019] [Accepted: 08/20/2019] [Indexed: 11/13/2022] Open
Abstract
During the critical period, neuronal connections are shaped by sensory experience. While the basis for this temporarily heightened plasticity remains unclear, shared connections introducing activity correlations likely play a key role. Thus, we investigated the changing intracortical connectivity in primary auditory cortex (A1) over development. In adult, layer 2/3 (L2/3) neurons receive ascending inputs from layer 4 (L4) and also receive few inputs from subgranular layer 5/6 (L5/6). We measured the spatial pattern of intracortical excitatory and inhibitory connections to L2/3 neurons in slices of mouse A1 across development using laser-scanning photostimulation. Before P11, L2/3 cells receive most excitatory input from within L2/3. Excitatory inputs from L2/3 and L4 increase after P5 and peak during P9-16. L5/6 inputs increase after P5 and provide most input during P12-16, the peak of the critical period. Inhibitory inputs followed a similar pattern. Functional circuit diversity in L2/3 emerges after P16. In vivo two-photon imaging shows low pairwise signal correlations in neighboring neurons before P11, which peak at P15-16 and decline after. Our results suggest that the critical period is characterized by high pairwise activity correlations and that transient hyperconnectivity of specific circuits, in particular those originating in L5/6, might play a key role.
Collapse
Affiliation(s)
- Xiangying Meng
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Krystyna Solarana
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Zac Bowen
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Ji Liu
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Daniel A Nagode
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Aminah Sheikh
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Daniel E Winkowski
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Joseph P Y Kao
- Center for Biomedical Engineering and Technology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Patrick O Kanold
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| |
Collapse
|
4
|
The extracellular matrix regulates cortical layer dynamics and cross-columnar frequency integration in the auditory cortex. Commun Biol 2021; 4:322. [PMID: 33692502 PMCID: PMC7946889 DOI: 10.1038/s42003-021-01837-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 02/11/2021] [Indexed: 01/31/2023] Open
Abstract
In the adult vertebrate brain, enzymatic removal of the extracellular matrix (ECM) is increasingly recognized to promote learning, memory recall, and restorative plasticity. The impact of the ECM on translaminar dynamics during cortical circuit processing is still not understood. Here, we removed the ECM in the primary auditory cortex (ACx) of adult Mongolian gerbils using local injections of hyaluronidase (HYase). Using laminar current-source density (CSD) analysis, we found layer-specific changes of the spatiotemporal synaptic patterns with increased cross-columnar integration and simultaneous weakening of early local sensory input processing within infragranular layers Vb. These changes had an oscillatory fingerprint within beta-band (25-36 Hz) selectively within infragranular layers Vb. To understand the laminar interaction dynamics after ECM digestion, we used time-domain conditional Granger causality (GC) measures to identify the increased drive of supragranular layers towards deeper infragranular layers. These results showed that ECM degradation altered translaminar cortical network dynamics with a stronger supragranular lead of the columnar response profile.
Collapse
|
5
|
Deng R, Kao JPY, Kanold PO. Aberrant development of excitatory circuits to inhibitory neurons in the primary visual cortex after neonatal binocular enucleation. Sci Rep 2021; 11:3163. [PMID: 33542365 PMCID: PMC7862622 DOI: 10.1038/s41598-021-82679-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 01/22/2021] [Indexed: 11/09/2022] Open
Abstract
The development of GABAergic interneurons is important for the functional maturation of cortical circuits. After migrating into the cortex, GABAergic interneurons start to receive glutamatergic connections from cortical excitatory neurons and thus gradually become integrated into cortical circuits. These glutamatergic connections are mediated by glutamate receptors including AMPA and NMDA receptors and the ratio of AMPA to NMDA receptors decreases during development. Since previous studies have shown that retinal input can regulate the early development of connections along the visual pathway, we investigated if the maturation of glutamatergic inputs to GABAergic interneurons in the visual cortex requires retinal input. We mapped the spatial pattern of glutamatergic connections to layer 4 (L4) GABAergic interneurons in mouse visual cortex at around postnatal day (P) 16 by laser-scanning photostimulation and investigated the effect of binocular enucleations at P1/P2 on these patterns. Gad2-positive interneurons in enucleated animals showed an increased fraction of AMPAR-mediated input from L2/3 and a decreased fraction of input from L5/6. Parvalbumin-expressing (PV) interneurons showed similar changes in relative connectivity. NMDAR-only input was largely unchanged by enucleation. Our results show that retinal input sculpts the integration of interneurons into V1 circuits and suggest that the development of AMPAR- and NMDAR-only connections might be regulated differently.
Collapse
Affiliation(s)
- Rongkang Deng
- Department of Biology, University of Maryland, College Park, MD, 20742, USA.,Biological Sciences Graduate Program, University of Maryland, College Park, 20742, MD, USA
| | - Joseph P Y Kao
- Center for Biomedical Engineering and Technology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Patrick O Kanold
- Department of Biomedical Engineering, Johns Hopkins University, 379 Miller Res. Bldg, Baltimore, MD, 21205, USA. .,Department of Biology, University of Maryland, College Park, MD, 20742, USA.
| |
Collapse
|
6
|
Del Rio-Bermudez C, Kim J, Sokoloff G, Blumberg MS. Active Sleep Promotes Coherent Oscillatory Activity in the Cortico-Hippocampal System of Infant Rats. Cereb Cortex 2020; 30:2070-2082. [PMID: 31922194 PMCID: PMC7175014 DOI: 10.1093/cercor/bhz223] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2019] [Revised: 08/09/2019] [Accepted: 08/28/2019] [Indexed: 12/12/2022] Open
Abstract
Active sleep (AS) provides a unique developmental context for synchronizing neural activity within and between cortical and subcortical structures. In week-old rats, sensory feedback from myoclonic twitches, the phasic motor activity that characterizes AS, promotes coherent theta oscillations (4-8 Hz) in the hippocampus and red nucleus, a midbrain motor structure. Sensory feedback from twitches also triggers rhythmic activity in sensorimotor cortex in the form of spindle bursts, which are brief oscillatory events composed of rhythmic components in the theta, alpha/beta (8-20 Hz), and beta2 (20-30 Hz) bands. Here we ask whether one or more of these spindle-burst components are communicated from sensorimotor cortex to hippocampus. By recording simultaneously from whisker barrel cortex and dorsal hippocampus in 8-day-old rats, we show that AS, but not other behavioral states, promotes cortico-hippocampal coherence specifically in the beta2 band. By cutting the infraorbital nerve to prevent the conveyance of sensory feedback from whisker twitches, cortical-hippocampal beta2 coherence during AS was substantially reduced. These results demonstrate the necessity of sensory input, particularly during AS, for coordinating rhythmic activity between these two developing forebrain structures.
Collapse
Affiliation(s)
- Carlos Del Rio-Bermudez
- Department of Psychological and Brain Sciences, University of Iowa, Iowa City, IA 52242, USA
| | - Jangjin Kim
- Department of Psychological and Brain Sciences, University of Iowa, Iowa City, IA 52242, USA
| | - Greta Sokoloff
- Department of Psychological and Brain Sciences, University of Iowa, Iowa City, IA 52242, USA
- Iowa Neuroscience Institute, University of Iowa, Iowa City, IA 52242, USA
| | - Mark S Blumberg
- Department of Psychological and Brain Sciences, University of Iowa, Iowa City, IA 52242, USA
- Iowa Neuroscience Institute, University of Iowa, Iowa City, IA 52242, USA
- Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, IA 52245, USA
| |
Collapse
|
7
|
Andreoli E, Petrenko V, Constanthin PE, Contestabile A, Bocchi R, Egervari K, Quairiaux C, Salmon P, Kiss JZ. Transplanted Embryonic Neurons Improve Functional Recovery by Increasing Activity in Injured Cortical Circuits. Cereb Cortex 2020; 30:4708-4725. [PMID: 32266929 DOI: 10.1093/cercor/bhaa075] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Revised: 02/07/2020] [Accepted: 03/06/2020] [Indexed: 12/11/2022] Open
Abstract
Transplantation of appropriate neuronal precursors after injury is a promising strategy to reconstruct cortical circuits, but the efficiency of these approaches remains limited. Here, we applied targeted apoptosis to selectively ablate layer II/III pyramidal neurons in the rat juvenile cerebral cortex and attempted to replace lost neurons with their appropriate embryonic precursors by transplantation. We demonstrate that grafted precursors do not migrate to replace lost neurons but form vascularized clusters establishing reciprocal synaptic contacts with host networks and show functional integration. These heterotopic neuronal clusters significantly enhance the activity of the host circuits without causing epileptic seizures and attenuate the apoptotic injury-induced functional deficits in electrophysiological and behavioral tests. Chemogenetic activation of grafted neurons further improved functional recovery, and the persistence of the graft was necessary for maintaining restored functions in adult animals. Thus, implanting neuronal precursors capable to form synaptically integrated neuronal clusters combined with activation-based approaches represents a useful strategy for helping long-term functional recovery following brain injury.
Collapse
Affiliation(s)
- Evgenia Andreoli
- Department of Basic Neurosciences, Faculty of Medicine, University of Geneva, 1 Rue Michel Servet, 1211 Geneva, Switzerland
| | - Volodymyr Petrenko
- Department of Basic Neurosciences, Faculty of Medicine, University of Geneva, 1 Rue Michel Servet, 1211 Geneva, Switzerland
| | - Paul Eugène Constanthin
- Department of Basic Neurosciences, Faculty of Medicine, University of Geneva, 1 Rue Michel Servet, 1211 Geneva, Switzerland
| | - Alessandro Contestabile
- Department of Basic Neurosciences, Faculty of Medicine, University of Geneva, 1 Rue Michel Servet, 1211 Geneva, Switzerland
| | - Riccardo Bocchi
- Department of Basic Neurosciences, Faculty of Medicine, University of Geneva, 1 Rue Michel Servet, 1211 Geneva, Switzerland
| | - Kristof Egervari
- Department of Basic Neurosciences, Faculty of Medicine, University of Geneva, 1 Rue Michel Servet, 1211 Geneva, Switzerland
| | - Charles Quairiaux
- Department of Basic Neurosciences, Faculty of Medicine, University of Geneva, 1 Rue Michel Servet, 1211 Geneva, Switzerland
| | - Patrick Salmon
- Department of Basic Neurosciences, Faculty of Medicine, University of Geneva, 1 Rue Michel Servet, 1211 Geneva, Switzerland
| | - Jozsef Zoltan Kiss
- Department of Basic Neurosciences, Faculty of Medicine, University of Geneva, 1 Rue Michel Servet, 1211 Geneva, Switzerland
| |
Collapse
|
8
|
Booker SA, Domanski APF, Dando OR, Jackson AD, Isaac JTR, Hardingham GE, Wyllie DJA, Kind PC. Altered dendritic spine function and integration in a mouse model of fragile X syndrome. Nat Commun 2019; 10:4813. [PMID: 31645626 PMCID: PMC6811549 DOI: 10.1038/s41467-019-11891-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 07/23/2019] [Indexed: 12/23/2022] Open
Abstract
Cellular and circuit hyperexcitability are core features of fragile X syndrome and related autism spectrum disorder models. However, the cellular and synaptic bases of this hyperexcitability have proved elusive. We report in a mouse model of fragile X syndrome, glutamate uncaging onto individual dendritic spines yields stronger single-spine excitation than wild-type, with more silent spines. Furthermore, fewer spines are required to trigger an action potential with near-simultaneous uncaging at multiple spines. This is, in part, from increased dendritic gain due to increased intrinsic excitability, resulting from reduced hyperpolarization-activated currents, and increased NMDA receptor signaling. Using super-resolution microscopy we detect no change in dendritic spine morphology, indicating no structure-function relationship at this age. However, ultrastructural analysis shows a 3-fold increase in multiply-innervated spines, accounting for the increased single-spine glutamate currents. Thus, loss of FMRP causes abnormal synaptogenesis, leading to large numbers of poly-synaptic spines despite normal spine morphology, thus explaining the synaptic perturbations underlying circuit hyperexcitability. Fragile X syndrome and autism spectrum disorders are associated with circuit hyperexcitability, however, its cellular and synaptic bases are not well understood. Here, the authors report abnormal synaptogenesis with an increased prevalence of polysynaptic spines with normal morphology in a mouse model of fragile X.
Collapse
Affiliation(s)
- Sam A Booker
- Centre for Discovery Brain Sciences, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK.,Patrick Wild Centre, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK.,Simons Initiative for the Developing Brain, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK.,Centre for Brain Development and Repair, NCBS, GKVK Campus, Bangalore, 560065, India
| | - Aleksander P F Domanski
- Centre for Discovery Brain Sciences, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK.,School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol, UK
| | - Owen R Dando
- Centre for Discovery Brain Sciences, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK.,Patrick Wild Centre, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK.,Simons Initiative for the Developing Brain, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK.,Centre for Brain Development and Repair, NCBS, GKVK Campus, Bangalore, 560065, India.,UK Dementia Research Institute, University of Edinburgh, Chancellor's Buildings, Little France, Edinburgh, EH16 4SB, UK
| | - Adam D Jackson
- Centre for Discovery Brain Sciences, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK.,Patrick Wild Centre, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK.,Simons Initiative for the Developing Brain, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK.,Centre for Brain Development and Repair, NCBS, GKVK Campus, Bangalore, 560065, India
| | - John T R Isaac
- Developmental Synaptic Plasticity Section, NINDS, NIH, Bethesda, MD, 20892, USA.,Janssen Neuroscience, J&J London Innovation Centre, One Chapel Place, London, W1G 0B, UK
| | - Giles E Hardingham
- Centre for Discovery Brain Sciences, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK.,Patrick Wild Centre, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK.,Simons Initiative for the Developing Brain, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK.,Centre for Brain Development and Repair, NCBS, GKVK Campus, Bangalore, 560065, India.,UK Dementia Research Institute, University of Edinburgh, Chancellor's Buildings, Little France, Edinburgh, EH16 4SB, UK
| | - David J A Wyllie
- Centre for Discovery Brain Sciences, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK. .,Patrick Wild Centre, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK. .,Simons Initiative for the Developing Brain, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK. .,Centre for Brain Development and Repair, NCBS, GKVK Campus, Bangalore, 560065, India.
| | - Peter C Kind
- Centre for Discovery Brain Sciences, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK. .,Patrick Wild Centre, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK. .,Simons Initiative for the Developing Brain, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK. .,Centre for Brain Development and Repair, NCBS, GKVK Campus, Bangalore, 560065, India.
| |
Collapse
|
9
|
Peruffo A, Corain L, Bombardi C, Centelleghe C, Grisan E, Graïc JM, Bontempi P, Grandis A, Cozzi B. The motor cortex of the sheep: laminar organization, projections and diffusion tensor imaging of the intracranial pyramidal and extrapyramidal tracts. Brain Struct Funct 2019; 224:1933-1946. [DOI: 10.1007/s00429-019-01885-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Accepted: 05/03/2019] [Indexed: 02/06/2023]
|
10
|
Kast RJ, Levitt P. Precision in the development of neocortical architecture: From progenitors to cortical networks. Prog Neurobiol 2019; 175:77-95. [PMID: 30677429 PMCID: PMC6402587 DOI: 10.1016/j.pneurobio.2019.01.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 01/02/2019] [Accepted: 01/21/2019] [Indexed: 02/07/2023]
Abstract
Of all brain regions, the 6-layered neocortex has undergone the most dramatic changes in size and complexity during mammalian brain evolution. These changes, occurring in the context of a conserved set of organizational features that emerge through stereotypical developmental processes, are considered responsible for the cognitive capacities and sensory specializations represented within the mammalian clade. The modern experimental era of developmental neurobiology, spanning 6 decades, has deciphered a number of mechanisms responsible for producing the diversity of cortical neuron types, their precise connectivity and the role of gene by environment interactions. Here, experiments providing insight into the development of cortical projection neuron differentiation and connectivity are reviewed. This current perspective integrates discussion of classic studies and new findings, based on recent technical advances, to highlight an improved understanding of the neuronal complexity and precise connectivity of cortical circuitry. These descriptive advances bring new opportunities for studies related to the developmental origins of cortical circuits that will, in turn, improve the prospects of identifying pathogenic targets of neurodevelopmental disorders.
Collapse
Affiliation(s)
- Ryan J Kast
- Department of Pediatrics and Program in Developmental Neuroscience and Developmental Neurogenetics, The Saban Research Institute, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90027, USA
| | - Pat Levitt
- Department of Pediatrics and Program in Developmental Neuroscience and Developmental Neurogenetics, The Saban Research Institute, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90027, USA.
| |
Collapse
|
11
|
Whitehead K, Meek J, Fabrizi L. Developmental trajectory of movement-related cortical oscillations during active sleep in a cross-sectional cohort of pre-term and full-term human infants. Sci Rep 2018; 8:17516. [PMID: 30504857 PMCID: PMC6269518 DOI: 10.1038/s41598-018-35850-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 11/09/2018] [Indexed: 12/13/2022] Open
Abstract
In neonatal animal models, isolated limb movements during active sleep provide input to immature somatomotor cortex necessary for its development and are somatotopically encoded by alpha-beta oscillations as late as the equivalent of human full-term. Limb movements elicit similar neural patterns in very pre-term human infants (average 30 corrected gestational weeks), suggesting an analogous role in humans, but it is unknown until when they subserve this function. In a cohort of 19 neonates (31-42 corrected gestational weeks) we showed that isolated hand movements during active sleep continue to induce these same somatotopically distributed oscillations well into the perinatal period, but that these oscillations decline towards full-term and fully disappear at 41 corrected gestational weeks (equivalent to the end of gestation). We also showed that these highly localised alpha-beta oscillations are associated with an increase in delta oscillations which extends to the frontal area and does not decline with age. These results suggest that isolated limb movements during active sleep could have an important role in experience-dependent somatomotor development up until normal birth in humans.
Collapse
Affiliation(s)
- Kimberley Whitehead
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, United Kingdom.
| | - Judith Meek
- Elizabeth Garrett Anderson Obstetric Wing, University College London Hospitals, London, WC1E 6BD, United Kingdom
| | - Lorenzo Fabrizi
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, United Kingdom
| |
Collapse
|
12
|
Vinokurova D, Zakharov AV, Lebedeva J, Burkhanova GF, Chernova KA, Lotfullina N, Khazipov R, Valeeva G. Pharmacodynamics of the Glutamate Receptor Antagonists in the Rat Barrel Cortex. Front Pharmacol 2018; 9:698. [PMID: 30018551 PMCID: PMC6038834 DOI: 10.3389/fphar.2018.00698] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Accepted: 06/08/2018] [Indexed: 02/01/2023] Open
Abstract
Epipial application is one of the approaches for drug delivery into the cortex. However, passive diffusion of epipially applied drugs through the cortical depth may be slow, and different drug concentrations may be achieved at different rates across the cortical depth. Here, we explored the pharmacodynamics of the inhibitory effects of epipially applied ionotropic glutamate receptor antagonists CNQX and dAPV on sensory-evoked and spontaneous activity across layers of the cortical barrel column in urethane-anesthetized rats. The inhibitory effects of CNQX and dAPV were observed at concentrations that were an order higher than in slices in vitro, and they slowly developed from the cortical surface to depth after epipial application. The level of the inhibitory effects also followed the surface-to-depth gradient, with full inhibition of sensory evoked potentials (SEPs) in the supragranular layers and L4 and only partial inhibition in L5 and L6. During epipial CNQX and dAPV application, spontaneous activity and the late component of multiple unit activity (MUA) during sensory-evoked responses were suppressed faster than the short-latency MUA component. Despite complete suppression of SEPs in L4, sensory-evoked short-latency multiunit responses in L4 persisted, and they were suppressed by further addition of lidocaine suggesting that spikes in thalamocortical axons contribute ∼20% to early multiunit responses. Epipial CNQX and dAPV also completely suppressed sensory-evoked very fast (∼500 Hz) oscillations and spontaneous slow wave activity in L2/3 and L4. However, delta oscillations persisted in L5/6. Thus, CNQX and dAPV exert inhibitory actions on cortical activity during epipial application at much higher concentrations than in vitro, and the pharmacodynamics of their inhibitory effects is characterized by the surface-to-depth gradients in the rate of development and the level of inhibition of sensory-evoked and spontaneous cortical activity.
Collapse
Affiliation(s)
- Daria Vinokurova
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia.,Mediterranean Institute of Neurobiology - National Institute of Health and Medical Research, Aix-Marseille University, UMR1249, Marseille, France
| | | | - Julia Lebedeva
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia
| | | | | | - Nailya Lotfullina
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia.,Mediterranean Institute of Neurobiology - National Institute of Health and Medical Research, Aix-Marseille University, UMR1249, Marseille, France
| | - Rustem Khazipov
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia.,Mediterranean Institute of Neurobiology - National Institute of Health and Medical Research, Aix-Marseille University, UMR1249, Marseille, France
| | - Guzel Valeeva
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia
| |
Collapse
|
13
|
Del Rio-Bermudez C, Blumberg MS. Active Sleep Promotes Functional Connectivity in Developing Sensorimotor Networks. Bioessays 2018; 40:e1700234. [PMID: 29508913 PMCID: PMC6247910 DOI: 10.1002/bies.201700234] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Revised: 02/01/2018] [Indexed: 12/15/2022]
Abstract
A ubiquitous feature of active (REM) sleep in mammals and birds is its relative abundance in early development. In rat pups across the first two postnatal weeks, active sleep promotes the expression of synchronized oscillatory activity within and between cortical and subcortical sensorimotor structures. Sensory feedback from self-generated myoclonic twitches - which are produced exclusively during active sleep - also triggers neural oscillations in those structures. We have proposed that one of the functions of active sleep in early infancy is to provide a context for synchronizing developing structures. Specifically, neural oscillations contribute to a variety of neurodevelopmental processes, including synapse formation, neuronal differentiation and migration, apoptosis, and the refinement of topographic maps. In addition, synchronized oscillations promote functional connectivity between distant brain areas. Consequently, any condition or manipulation that restricts active sleep can, in turn, deprive the infant animal of substantial sensory experience, resulting in atypical developmental trajectories.
Collapse
Affiliation(s)
- Carlos Del Rio-Bermudez
- Department of Psychological and Brain Sciences, University of Iowa, Iowa City, 52242, Iowa, USA
- Delta Center, University of Iowa, Iowa City, 52242, Iowa, USA
| | - Mark S Blumberg
- Department of Psychological and Brain Sciences, University of Iowa, Iowa City, 52242, Iowa, USA
- Delta Center, University of Iowa, Iowa City, 52242, Iowa, USA
- Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, 52245, Iowa, USA
- Department of Biology, University of Iowa, Iowa City, 52242, Iowa, USA
- Iowa Neuroscience Institute, University of Iowa, Iowa City, 52242, Iowa, USA
| |
Collapse
|
14
|
Khazipov R, Milh M. Early patterns of activity in the developing cortex: Focus on the sensorimotor system. Semin Cell Dev Biol 2018; 76:120-129. [DOI: 10.1016/j.semcdb.2017.09.014] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 09/07/2017] [Accepted: 09/08/2017] [Indexed: 02/08/2023]
|
15
|
The Nature of the Sensory Input to the Neonatal Rat Barrel Cortex. J Neurosci 2017; 36:9922-32. [PMID: 27656029 DOI: 10.1523/jneurosci.1781-16.2016] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 08/07/2016] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Sensory input plays critical roles in the development of the somatosensory cortex during the neonatal period. This early sensory input may involve: (1) stimulation arising from passive interactions with the mother and littermates and (2) sensory feedback arising from spontaneous infant movements. The relative contributions of these mechanisms under natural conditions remain largely unknown, however. Here, we show that, in the whisker-related barrel cortex of neonatal rats, spontaneous whisker movements and passive stimulation by the littermates cooperate, with comparable efficiency, in driving cortical activity. Both tactile signals arising from the littermate's movements under conditions simulating the littermates' position in the litter, and spontaneous whisker movements efficiently triggered bursts of activity in barrel cortex. Yet, whisker movements with touch were more efficient than free movements. Comparison of the various experimental conditions mimicking the natural environment showed that tactile signals arising from the whisker movements with touch and stimulation by the littermates, support: (1) a twofold higher level of cortical activity than in the isolated animal, and (2) a threefold higher level of activity than in the deafferented animal after the infraorbital nerve cut. Together, these results indicate that endogenous (self-generated movements) and exogenous (stimulation by the littermates) mechanisms cooperate in driving cortical activity in newborn rats and point to the importance of the environment in shaping cortical activity during the neonatal period. SIGNIFICANCE STATEMENT Sensory input plays critical roles in the development of the somatosensory cortex during the neonatal period. However, the origins of sensory input to the neonatal somatosensory cortex in the natural environment remain largely unknown. Here, we show that in the whisker-related barrel cortex of neonatal rats, spontaneous whisker movements and passive stimulation by the littermates cooperate, with comparable efficiency, in driving cortical activity during the critical developmental period.
Collapse
|
16
|
Currie SP, Luz LL, Booker SA, Wyllie DJA, Kind PC, Daw MI. Reduced local input to fast-spiking interneurons in the somatosensory cortex in the GABA A γ2 R43Q mouse model of absence epilepsy. Epilepsia 2017; 58:597-607. [PMID: 28195311 PMCID: PMC5412680 DOI: 10.1111/epi.13693] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/04/2017] [Indexed: 02/04/2023]
Abstract
Objective Absence seizures in childhood absence epilepsy are initiated in the thalamocortical (TC) system. We investigated if these seizures result from altered development of the TC system before the appearance of seizures in mice containing a point mutation in γ‐aminobutyric acid A (GABAA) receptor γ2 subunits linked to childhood absence epilepsy (R43Q). Findings from conditional mutant mice indicate that expression of normal γ2 subunits during preseizure ages protect from later seizures. This indicates that altered development in the presence of the R43Q mutation is a key contributor to the R43Q phenotype. We sought to identify the cellular processes affected by the R43Q mutation during these preseizure ages. Methods We examined landmarks of synaptic development at the end of the critical period for somatosensory TC plasticity using electrophysiologic recordings in TC brain slices from wild‐type mice and R43Q mice. Results We found that the level of TC connectivity to layer 4 (L4) principal cells and the properties of TC synapses were unaltered in R43Q mice. Furthermore, we show that, although TC feedforward inhibition and the total level of GABAergic inhibition were normal, there was a reduction in the local connectivity to cortical interneurons. This reduction leads to altered inhibition during bursts of cortical activity. Significance This altered inhibition demonstrates that alterations in cortical circuitry precede the onset of seizures by more than a week.
Collapse
Affiliation(s)
- Stephen P Currie
- Muir Maxwell Epilepsy Centre, Patrick Wild Centre, Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Liliana L Luz
- Muir Maxwell Epilepsy Centre, Patrick Wild Centre, Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Sam A Booker
- Muir Maxwell Epilepsy Centre, Patrick Wild Centre, Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| | - David J A Wyllie
- Muir Maxwell Epilepsy Centre, Patrick Wild Centre, Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom.,Centre for Brain Development and Repair, InStem, Bangalore, India
| | - Peter C Kind
- Muir Maxwell Epilepsy Centre, Patrick Wild Centre, Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom.,Centre for Brain Development and Repair, InStem, Bangalore, India
| | - Michael I Daw
- Muir Maxwell Epilepsy Centre, Patrick Wild Centre, Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
| |
Collapse
|
17
|
Alterations in the properties of neonatal thalamocortical synapses with time in in vitro slices. PLoS One 2017; 12:e0171897. [PMID: 28178342 PMCID: PMC5298242 DOI: 10.1371/journal.pone.0171897] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 01/27/2017] [Indexed: 11/19/2022] Open
Abstract
New synapses are constantly being generated and lost in the living brain with only a subset of these being stabilized to form an enduring component of neuronal circuitry. The properties of synaptic transmission have primarily been established in a variety of in vitro neuronal preparations. It is not clear, however, if newly-formed and persistent synapses contribute to the results of these studies consistently throughout the lifespan of these preparations. In neonatal somatosensory, barrel, cortex we have previously hypothesized that a population of thalamocortical synapses displaying unusually slow kinetics represent newly-formed, default-transient synapses. This clear phenotype would provide an ideal tool to investigate if such newly formed synapses consistently contribute to synaptic transmission throughout a normal experimental protocol. We show that the proportion of synapses recorded in vitro displaying slow kinetics decreases with time after brain slice preparation. However, slow synapses persist in vitro in the presence of either minocycline, an inhibitor of microglia-mediated synapse elimination, or the TrkB agonist 7,8-dihydroxyflavone a promoter of synapse formation. These findings show that the observed properties of synaptic transmission may systematically change with time in vitro in a standard brain slice preparation.
Collapse
|
18
|
Crocker-Buque A, Currie SP, Luz LL, Grant SG, Duffy KR, Kind PC, Daw MI. Altered thalamocortical development in the SAP102 knockout model of intellectual disability. Hum Mol Genet 2016; 25:4052-4061. [PMID: 27466188 PMCID: PMC5291236 DOI: 10.1093/hmg/ddw244] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 06/24/2016] [Accepted: 07/13/2016] [Indexed: 12/30/2022] Open
Abstract
Genetic mutations known to cause intellectual disabilities (IDs) are concentrated in specific sets of genes including both those encoding synaptic proteins and those expressed during early development. We have characterized the effect of genetic deletion of Dlg3, an ID-related gene encoding the synaptic NMDA-receptor interacting protein synapse-associated protein 102 (SAP102), on development of the mouse somatosensory cortex. SAP102 is the main representative of the PSD-95 family of postsynaptic MAGUK proteins during early development and is proposed to play a role in stabilizing receptors at immature synapses. Genetic deletion of SAP102 caused a reduction in the total number of thalamocortical (TC) axons innervating the somatosensory cortex, but did not affect the segregation of barrels. On a synaptic level SAP102 knockout mice display a transient speeding of NMDA receptor kinetics during the critical period for TC plasticity, despite no reduction in GluN2B-mediated component of synaptic transmission. These data indicated an interesting dissociation between receptor kinetics and NMDA subunit expression. Following the critical period NMDA receptor function was unaffected by loss of SAP102 but there was a reduction in the divergence of TC connectivity. These data suggest that changes in synaptic function early in development caused by mutations in SAP102 result in changes in network connectivity later in life.
Collapse
Affiliation(s)
- Alex Crocker-Buque
- Centre for Integrative Physiology and Patrick Wild Centre, University of Edinburgh, Edinburgh EH8 9XD, UK
| | - Stephen P Currie
- Centre for Integrative Physiology and Patrick Wild Centre, University of Edinburgh, Edinburgh EH8 9XD, UK
| | - Liliana L Luz
- Centre for Integrative Physiology and Patrick Wild Centre, University of Edinburgh, Edinburgh EH8 9XD, UK
| | - Seth G Grant
- Centre for Clinical Brain Sciences, University of Edinburgh, Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB, UK
| | - Kevin R Duffy
- Department of Psychology and Neuroscience, Dalhousie University, 1355 Oxford Street, Halifax, NS B3H 4R2, Canada
| | - Peter C Kind
- Centre for Integrative Physiology and Patrick Wild Centre, University of Edinburgh, Edinburgh EH8 9XD, UK .,Centre for Brain Development and Repair, InStem, Bangalore 560065, India
| | - Michael I Daw
- Centre for Integrative Physiology and Patrick Wild Centre, University of Edinburgh, Edinburgh EH8 9XD, UK
| |
Collapse
|
19
|
Marques-Smith A, Lyngholm D, Kaufmann AK, Stacey JA, Hoerder-Suabedissen A, Becker EBE, Wilson MC, Molnár Z, Butt SJB. A Transient Translaminar GABAergic Interneuron Circuit Connects Thalamocortical Recipient Layers in Neonatal Somatosensory Cortex. Neuron 2016; 89:536-49. [PMID: 26844833 PMCID: PMC4742537 DOI: 10.1016/j.neuron.2016.01.015] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 08/28/2015] [Accepted: 01/06/2016] [Indexed: 01/06/2023]
Abstract
GABAergic activity is thought to influence developing neocortical sensory circuits. Yet the late postnatal maturation of local layer (L)4 circuits suggests alternate sources of GABAergic control in nascent thalamocortical networks. We show that a population of L5b, somatostatin (SST)-positive interneuron receives early thalamic synaptic input and, using laser-scanning photostimulation, identify an early transient circuit between these cells and L4 spiny stellates (SSNs) that disappears by the end of the L4 critical period. Sensory perturbation disrupts the transition to a local GABAergic circuit, suggesting a link between translaminar and local control of SSNs. Conditional silencing of SST+ interneurons or conversely biasing the circuit toward local inhibition by overexpression of neuregulin-1 type 1 results in an absence of early L5b GABAergic input in mutants and delayed thalamic innervation of SSNs. These data identify a role for L5b SST+ interneurons in the control of SSNs in the early postnatal neocortex. Early postnatal thalamic synaptic input onto L5b somatostatin interneurons Transient reciprocal connectivity between L5b INs and L4 spiny stellate cells Sensory activity is required for the transition to a local L4 GABAergic circuit Molecular bias toward early local IN synapses delays thalamic innervation of SSNs
Collapse
Affiliation(s)
- Andre Marques-Smith
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3QX, UK
| | - Daniel Lyngholm
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3QX, UK
| | - Anna-Kristin Kaufmann
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3QX, UK
| | - Jacqueline A Stacey
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3QX, UK
| | | | - Esther B E Becker
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3QX, UK
| | - Michael C Wilson
- Department of Neurosciences, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA
| | - Zoltán Molnár
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3QX, UK
| | - Simon J B Butt
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3QX, UK.
| |
Collapse
|
20
|
Unbiased, High-Throughput Electron Microscopy Analysis of Experience-Dependent Synaptic Changes in the Neocortex. J Neurosci 2016; 35:16450-62. [PMID: 26674870 DOI: 10.1523/jneurosci.1573-15.2015] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Neocortical circuits can be altered by sensory and motor experience, with experimental evidence supporting both anatomical and electrophysiological changes in synaptic properties. Previous studies have focused on changes in specific neurons or pathways-for example, the thalamocortical circuitry, layer 4-3 (L4-L3) synapses, or in the apical dendrites of L5 neurons- but a broad-scale analysis of experience-induced changes across the cortical column has been lacking. Without this comprehensive approach, a full understanding of how cortical circuits adapt during learning or altered sensory input will be impossible. Here we adapt an electron microscopy technique that selectively labels synapses, in combination with a machine-learning algorithm for semiautomated synapse detection, to perform an unbiased analysis of developmental and experience-dependent changes in synaptic properties across an entire cortical column in mice. Synapse density and length were compared across development and during whisker-evoked plasticity. Between postnatal days 14 and 18, synapse density significantly increases most in superficial layers, and synapse length increases in L3 and L5B. Removal of all but a single whisker row for 24 h led to an apparent increase in synapse density in L2 and a decrease in L6, and a significant increase in length in L3. Targeted electrophysiological analysis of changes in miniature EPSC and IPSC properties in L2 pyramidal neurons showed that mEPSC frequency nearly doubled in the whisker-spared column, a difference that was highly significant. Together, this analysis shows that data-intensive analysis of column-wide changes in synapse properties can generate specific and testable hypotheses about experience-dependent changes in cortical organization. SIGNIFICANCE STATEMENT Development and sensory experience can change synapse properties in the neocortex. Here we use a semiautomated analysis of electron microscopy images for an unbiased, column-wide analysis of synapse changes. This analysis reveals new loci for synaptic change that can be verified by targeted electrophysiological investigation. This method can be used as a platform for generating new hypotheses about synaptic changes across different brain areas and experimental conditions.
Collapse
|
21
|
Valiullina F, Akhmetshina D, Nasretdinov A, Mukhtarov M, Valeeva G, Khazipov R, Rozov A. Developmental Changes in Electrophysiological Properties and a Transition from Electrical to Chemical Coupling between Excitatory Layer 4 Neurons in the Rat Barrel Cortex. Front Neural Circuits 2016; 10:1. [PMID: 26834567 PMCID: PMC4720737 DOI: 10.3389/fncir.2016.00001] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 01/02/2016] [Indexed: 11/22/2022] Open
Abstract
During development, sensory systems switch from an immature to an adult mode of function along with the emergence of the active cortical states. Here, we used patch-clamp recordings from neocortical slices in vitro to characterize the developmental changes in the basic electrophysiological properties of excitatory L4 neurons and their connectivity before and after the developmental switch, which occurs in the rat barrel cortex in vivo at postnatal day P8. Prior to the switch, L4 neurons had higher resting membrane potentials, higher input resistance, lower membrane capacity, as well as action potentials (APs) with smaller amplitudes, longer durations and higher AP thresholds compared to the neurons after the switch. A sustained firing pattern also emerged around the switch. Dual patch-clamp recordings from L4 neurons revealed that recurrent connections between L4 excitatory cells do not exist before and develop rapidly across the switch. In contrast, electrical coupling between these neurons waned around the switch. We suggest that maturation of electrophysiological features, particularly acquisition of a sustained firing pattern, and a transition from the immature electrical to mature chemical synaptic coupling between excitatory L4 neurons, contributes to the developmental switch in the cortical mode of function.
Collapse
Affiliation(s)
- Fliza Valiullina
- Laboratory of Neurobiology, Institute of Fundamental Medicine and Biology, Kazan Federal University Kazan, Russia
| | - Dinara Akhmetshina
- Laboratory of Neurobiology, Institute of Fundamental Medicine and Biology, Kazan Federal University Kazan, Russia
| | - Azat Nasretdinov
- Laboratory of Neurobiology, Institute of Fundamental Medicine and Biology, Kazan Federal University Kazan, Russia
| | - Marat Mukhtarov
- Laboratory of Neurobiology, Institute of Fundamental Medicine and Biology, Kazan Federal University Kazan, Russia
| | - Guzel Valeeva
- Laboratory of Neurobiology, Institute of Fundamental Medicine and Biology, Kazan Federal University Kazan, Russia
| | - Roustem Khazipov
- Laboratory of Neurobiology, Institute of Fundamental Medicine and Biology, Kazan Federal UniversityKazan, Russia; Institut de Neurobiologie de la Méditerranée, Institut National de la Santé et de la Recherche Médicale UMR901Marseille, France; Aix-Marseille UniversityMarseille, France
| | - Andrei Rozov
- Laboratory of Neurobiology, Institute of Fundamental Medicine and Biology, Kazan Federal UniversityKazan, Russia; Department of Physiology and Pathophysiology, University of HeidelbergHeidelberg, Germany
| |
Collapse
|