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Ronzano R, Thetiot M, Lubetzki C, Desmazieres A. Myelin Plasticity and Repair: Neuro-Glial Choir Sets the Tuning. Front Cell Neurosci 2020; 14:42. [PMID: 32180708 PMCID: PMC7059744 DOI: 10.3389/fncel.2020.00042] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Accepted: 02/12/2020] [Indexed: 12/11/2022] Open
Abstract
The plasticity of the central nervous system (CNS) in response to neuronal activity has been suggested as early as 1894 by Cajal (1894). CNS plasticity has first been studied with a focus on neuronal structures. However, in the last decade, myelin plasticity has been unraveled as an adaptive mechanism of importance, in addition to the previously described processes of myelin repair. Indeed, it is now clear that myelin remodeling occurs along with life and adapts to the activity of neuronal networks. Until now, it has been considered as a two-part dialog between the neuron and the oligodendroglial lineage. However, other glial cell types might be at play in myelin plasticity. In the present review, we first summarize the key structural parameters for myelination, we then describe how neuronal activity modulates myelination and finally discuss how other glial cells could participate in myelinic adaptivity.
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Affiliation(s)
- Remi Ronzano
- Institut du Cerveau et de la Moelle épinière, Sorbonne Universités UPMC Université Paris 06, CNRS UMR7225-Inserm U1127, Paris, France
| | - Melina Thetiot
- Institut du Cerveau et de la Moelle épinière, Sorbonne Universités UPMC Université Paris 06, CNRS UMR7225-Inserm U1127, Paris, France
- Unit Zebrafish Neurogenetics, Department of Developmental & Stem Cell Biology, Institut Pasteur, CNRS, Paris, France
| | - Catherine Lubetzki
- Institut du Cerveau et de la Moelle épinière, Sorbonne Universités UPMC Université Paris 06, CNRS UMR7225-Inserm U1127, Paris, France
- Assistance Publique-Hôpitaux de Paris, Hôpital Pitié-Salpêtrière, Paris, France
| | - Anne Desmazieres
- Institut du Cerveau et de la Moelle épinière, Sorbonne Universités UPMC Université Paris 06, CNRS UMR7225-Inserm U1127, Paris, France
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52
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Extraretinal Spike Normalization in Retinal Ganglion Cell Axons. eNeuro 2020; 7:ENEURO.0504-19.2020. [PMID: 32086286 PMCID: PMC7110362 DOI: 10.1523/eneuro.0504-19.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 01/24/2020] [Accepted: 02/10/2020] [Indexed: 11/21/2022] Open
Abstract
Spike conduction velocity characteristically differs between myelinated and unmyelinated axons. Here we test whether spikes of myelinated and unmyelinated paths differ in other respects by measuring rat retinal ganglion cell (RGC) spike duration in the intraretinal, unmyelinated nerve fiber layer and the extraretinal, myelinated optic nerve and optic chiasm. We find that rapid spike firing and illumination broaden spikes in intraretinal axons but not in extraretinal axons. RGC axons thus initiate spikes intraretinally and normalize spike duration extraretinally. Additionally, we analyze spikes that were recorded in a previous study of rhesus macaque retinogeniculate transmission and find that rapid spike firing does not broaden spikes in optic tract. The spike normalization we find reduces the number of spike properties that can change during RGC light responses. However, this is not because identical spikes fire in all axons. Instead, our recordings show that different subtypes of RGC generate axonal spikes of different durations and that the differences resemble spike duration increases that alter neurotransmitter release from other neurons. Moreover, previous studies have shown that RGC spikes of shorter duration can fire at higher maximum frequencies. These properties should facilitate signal transfer by different mechanisms at RGC synapses onto subcortical target neurons.
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53
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Egger R, Narayanan RT, Guest JM, Bast A, Udvary D, Messore LF, Das S, de Kock CPJ, Oberlaender M. Cortical Output Is Gated by Horizontally Projecting Neurons in the Deep Layers. Neuron 2019; 105:122-137.e8. [PMID: 31784285 PMCID: PMC6953434 DOI: 10.1016/j.neuron.2019.10.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 09/01/2019] [Accepted: 10/02/2019] [Indexed: 12/13/2022]
Abstract
Pyramidal tract neurons (PTs) represent the major output cell type of the mammalian neocortex. Here, we report the origins of the PTs’ ability to respond to a broad range of stimuli with onset latencies that rival or even precede those of their intracortical input neurons. We find that neurons with extensive horizontally projecting axons cluster around the deep-layer terminal fields of primary thalamocortical axons. The strategic location of these corticocortical neurons results in high convergence of thalamocortical inputs, which drive reliable sensory-evoked responses that precede those in other excitatory cell types. The resultant fast and horizontal stream of excitation provides PTs throughout the cortical area with input that acts to amplify additional inputs from thalamocortical and other intracortical populations. The fast onsets and broadly tuned characteristics of PT responses hence reflect a gating mechanism in the deep layers, which assures that sensory-evoked input can be reliably transformed into cortical output. Simulations predict in vivo responses for major output cell type of the neocortex Simulations reveal strategy how to test the origins of cortical output empirically Manipulations confirm that deep-layer corticocortical neurons gate cortical output Gating of cortical output originates from deep-layer thalamocortical input stratum
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Affiliation(s)
- Robert Egger
- Max Planck Research Group In Silico Brain Sciences, Center of Advanced European Studies and Research (caesar), Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Rajeevan T Narayanan
- Max Planck Research Group In Silico Brain Sciences, Center of Advanced European Studies and Research (caesar), Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Jason M Guest
- Max Planck Research Group In Silico Brain Sciences, Center of Advanced European Studies and Research (caesar), Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Arco Bast
- Max Planck Research Group In Silico Brain Sciences, Center of Advanced European Studies and Research (caesar), Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Daniel Udvary
- Max Planck Research Group In Silico Brain Sciences, Center of Advanced European Studies and Research (caesar), Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Luis F Messore
- Max Planck Research Group In Silico Brain Sciences, Center of Advanced European Studies and Research (caesar), Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Suman Das
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, VU Amsterdam, De Boelelaan 1085, 1081 Amsterdam, the Netherlands
| | - Christiaan P J de Kock
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, VU Amsterdam, De Boelelaan 1085, 1081 Amsterdam, the Netherlands
| | - Marcel Oberlaender
- Max Planck Research Group In Silico Brain Sciences, Center of Advanced European Studies and Research (caesar), Ludwig-Erhard-Allee 2, 53175 Bonn, Germany.
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54
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Chapman TW, Hill RA. Myelin plasticity in adulthood and aging. Neurosci Lett 2019; 715:134645. [PMID: 31765728 DOI: 10.1016/j.neulet.2019.134645] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 11/06/2019] [Accepted: 11/21/2019] [Indexed: 12/31/2022]
Abstract
The central nervous system maintains the potential for molecular and cellular plasticity throughout life. This flexibility underlies fundamental features of neural circuitry including the brain's ability to sense, store, and properly adapt to everchanging external stimuli on time scales from seconds to years. Evidence for most forms of plasticity are centered around changes in neuronal structure and synaptic strength, however recent data suggests that myelinating oligodendrocytes exhibit certain forms of plasticity in the adult. This plasticity ranges from the generation of entirely new myelinating cells to more subtle changes in myelin sheath length, thickness, and distribution along axons. The extent to which these changes dynamically modify axonal function and neural circuitry and whether they are directly related to mechanisms of learning and memory remains an open question. Here we describe different forms of myelin plasticity, highlight some recent evidence for changes in myelination throughout life, and discuss how defects in these forms of plasticity could be associated with cognitive decline in aging.
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Affiliation(s)
- Timothy W Chapman
- Department of Biological Sciences, Dartmouth College, Hanover, NH, USA
| | - Robert A Hill
- Department of Biological Sciences, Dartmouth College, Hanover, NH, USA.
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55
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Santuy A, Turégano-López M, Rodríguez JR, Alonso-Nanclares L, DeFelipe J, Merchán-Pérez A. A Quantitative Study on the Distribution of Mitochondria in the Neuropil of the Juvenile Rat Somatosensory Cortex. Cereb Cortex 2019; 28:3673-3684. [PMID: 30060007 PMCID: PMC6132283 DOI: 10.1093/cercor/bhy159] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 06/14/2018] [Indexed: 12/17/2022] Open
Abstract
Mitochondria play a key role in energy production and calcium buffering, among many other functions. They provide most of the energy required by neurons, and they are transported along axons and dendrites to the regions of higher energy demands. We have used focused ion beam milling and scanning electron microscopy (FIB/SEM) to obtain stacks of serial sections from the somatosensory cortex of the juvenile rat. We have estimated the volume fraction occupied by mitochondria and their distribution between dendritic, axonal, and nonsynaptic processes. The volume fraction of mitochondria increased from layer I (4.59%) to reach its maximum in layer IV (7.74%) and decreased to its minimum in layer VI (4.03%). On average, 44% of mitochondrial volume was located in dendrites, 15% in axons and 41% in nonsynaptic elements. Given that dendrites, axons, and nonsynaptic elements occupied 38%, 23%, and 39% of the neuropil, respectively, it can be concluded that dendrites are proportionally richer in mitochondria with respect to axons, supporting the notion that most energy consumption takes place at the postsynaptic side. We also found a positive correlation between the volume fraction of mitochondria located in neuronal processes and the density of synapses.
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Affiliation(s)
- A Santuy
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Pozuelo de Alarcón, Madrid, Spain
| | - M Turégano-López
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Pozuelo de Alarcón, Madrid, Spain
| | - J R Rodríguez
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Pozuelo de Alarcón, Madrid, Spain.,Departamento de Neurobiología Funcional y de Sistemas, Instituto Cajal, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - L Alonso-Nanclares
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Pozuelo de Alarcón, Madrid, Spain.,Departamento de Neurobiología Funcional y de Sistemas, Instituto Cajal, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - J DeFelipe
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Pozuelo de Alarcón, Madrid, Spain.,Departamento de Neurobiología Funcional y de Sistemas, Instituto Cajal, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - A Merchán-Pérez
- Laboratorio Cajal de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Pozuelo de Alarcón, Madrid, Spain.,Departamento de Arquitectura y Tecnología de Sistemas Informáticos, Universidad Politécnica de Madrid, Boadilla del Monte, Madrid, Spain
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56
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Suminaite D, Lyons DA, Livesey MR. Myelinated axon physiology and regulation of neural circuit function. Glia 2019; 67:2050-2062. [PMID: 31233642 PMCID: PMC6772175 DOI: 10.1002/glia.23665] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 05/28/2019] [Accepted: 06/06/2019] [Indexed: 12/15/2022]
Abstract
The study of structural and functional plasticity in the central nervous system (CNS) to date has focused primarily on that of neurons and synapses. However, more recent studies implicate glial cells as key regulators of neural circuit function. Among these, the myelinating glia of the CNS, oligodendrocytes, have been shown to be responsive to extrinsic signals including neuronal activity, and in turn, tune neurophysiological function. Due to the fact that myelin fundamentally alters the conduction properties of axons, much attention has focused on how dynamic regulation of myelination might represent a form of functional plasticity. Here, we highlight recent research that indicates that it is not only myelin, but essentially all the function-regulating components of the myelinated axon that are responsive to neuronal activity. For example, the axon initial segment, nodes of Ranvier, heminodes, axonal termini, and the morphology of the axon itself all exhibit the potential to respond to neuronal activity, and in so doing might underpin specific functional outputs. We also highlight emerging evidence that the myelin sheath itself has a rich physiology capable of influencing axonal physiology. We suggest that to fully understand nervous system plasticity we need to consider the fact that myelinated axon is an integrated functional unit and adaptations that influence the entire functional unit are likely to underpin modifications to neural circuit function.
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Affiliation(s)
| | - David A. Lyons
- Centre for Discovery Brain SciencesUniversity of EdinburghEdinburghUK
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57
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Baumeister TR, Kolind SH, MacKay AL, McKeown MJ. Inherent spatial structure in myelin water fraction maps. Magn Reson Imaging 2019; 67:33-42. [PMID: 31677990 DOI: 10.1016/j.mri.2019.09.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 08/23/2019] [Accepted: 09/27/2019] [Indexed: 01/05/2023]
Abstract
Myelin water fraction (MWF) images in brain tend to be spatially noisy with unknown or no apparent spatial patterns structure, so values are therefore typically averaged over large white matter (WM) volumes. We investigated the existence of an inherent spatial structure in MWF maps and explored the benefits of examining MWF values along diffusion tensor imaging (DTI)-derived white matter tracts. We compared spatial anisotropy between MWF and the more widely-used fractional anisotropy (FA) measure. Sixteen major white matter fibre bundles were extracted based on DTI data from 41 healthy subjects. MWF coefficients of variation (CoV) were computed in sub-segments along each fibre tract and compared to MWF CoVs from the surrounding "tubes" - i.e. voxels just exterior to the tract - of each segment. We further assessed the consistency of the MWF along fibre bundles across subjects and investigated the benefit of examining MWF values in sections along each fibre bundle rather than integrating over the whole tract. CoVs of MWF and FA were lower in fibre bundles compared to their enclosing tubes in all investigated tracts. Both measures possessed a spatial gradient of CoV that was smaller aligned along, compared to perpendicular to, the fibre bundles. All WM tracts showed MWF profiles along their trajectory that were consistent across subjects and were more accurate than the mean overall fibre MWF value in estimating ages of the subjects. We conclude that, although less obvious visually, the spatial MWF distribution in white matter consistently follows a distinct pattern along underlying fibre bundles across subjects. Assessing MWF in sections along white matter tracts may provide a sensitive and robust way to assess myelin across subjects.
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Affiliation(s)
- Tobias R Baumeister
- School of Biomedical Engineering, The University of British Columbia, Canada
| | - Shannon H Kolind
- Faculty of Medicine, Division of Neurology, The University of British Columbia, Canada; Department of Radiology, The University of British Columbia, Canada; Department of Physics & Astronomy, The University of British Columbia, Canada
| | - Alex L MacKay
- Department of Radiology, The University of British Columbia, Canada; Department of Physics & Astronomy, The University of British Columbia, Canada
| | - Martin J McKeown
- Faculty of Medicine, Division of Neurology, The University of British Columbia, Canada.
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58
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Barnden LR, Shan ZY, Staines DR, Marshall-Gradisnik S, Finegan K, Ireland T, Bhuta S. Intra brainstem connectivity is impaired in chronic fatigue syndrome. NEUROIMAGE-CLINICAL 2019; 24:102045. [PMID: 31671321 PMCID: PMC6835065 DOI: 10.1016/j.nicl.2019.102045] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 08/27/2019] [Accepted: 10/17/2019] [Indexed: 11/16/2022]
Abstract
RAS connectivity was detected in HC and CFS groups both during rest and task. Strong connections were active for CFS from hippocampus to midbrain and medulla. RAS connectivity was diminished in CFS in the brainstem and to the hippocampus. RAS nuclei generate oscillatory signals which facilitate thalamocortical signal coherence. Impaired RAS affects cortical coherence necessary for attention, memory and problem solving.
In myalgic encephalomyelitis or chronic fatigue syndrome (ME/CFS), abnormal MRI correlations with symptom severity and autonomic measures have suggested impaired nerve signal conduction within the brainstem. Here we analyse fMRI correlations to directly test connectivity within and from the brainstem. Resting and task functional MRI (fMRI) were acquired for 45 ME/CFS (Fukuda criteria) and 27 healthy controls (HC). We selected limited brainstem reticular activation system (RAS) regions-of-interest (ROIs) based on previous structural MRI findings in a different ME/CFS cohort (bilateral rostral medulla and midbrain cuneiform nucleus), the dorsal Raphe nucleus, and two subcortical ROIs (hippocampus subiculum and thalamus intralaminar nucleus) reported to have rich brainstem connections. When HC and ME/CFS were analysed separately, significant correlations were detected for both groups during both rest and task, with stronger correlations during task than rest. In ME/CFS, connections were absent between medulla and midbrain nuclei, although hippocampal connections with these nuclei were enhanced. When corresponding correlations from HC and ME/CFS were compared, ME/CFS connectivity deficits were detected within the brainstem between the medulla and cuneiform nucleus and between the brainstem and hippocampus and intralaminar thalamus, but only during task. In CFS/ME, weaker connectivity between some RAS nuclei was associated with increased symptom severity. RAS neuron oscillatory signals facilitate coherence in thalamo-cortical oscillations. Brainstem RAS connectivity deficits can explain autonomic changes and diminish cortical oscillatory coherence which can impair attention, memory, cognitive function, sleep quality and muscle tone, all symptoms of ME/CFS.
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Affiliation(s)
- Leighton R Barnden
- National Centre for Neuroimmunology and Emerging Diseases, Menzies Health Institute Queensland, Griffith University, Southport, QLD 4222, Australia.
| | - Zack Y Shan
- National Centre for Neuroimmunology and Emerging Diseases, Menzies Health Institute Queensland, Griffith University, Southport, QLD 4222, Australia; Sunshine Coast Mind and Neuroscience Thompson Institute, University of the Sunshine Coast, Birtinya, QLD 4575, Australia.
| | - Donald R Staines
- National Centre for Neuroimmunology and Emerging Diseases, Menzies Health Institute Queensland, Griffith University, Southport, QLD 4222, Australia.
| | - Sonya Marshall-Gradisnik
- National Centre for Neuroimmunology and Emerging Diseases, Menzies Health Institute Queensland, Griffith University, Southport, QLD 4222, Australia.
| | - Kevin Finegan
- Medical Imaging Department, Gold Coast University Hospital, Parklands, QLD 4215, Australia.
| | - Timothy Ireland
- Medical Imaging Department, Gold Coast University Hospital, Parklands, QLD 4215, Australia.
| | - Sandeep Bhuta
- Medical Imaging Department, Gold Coast University Hospital, Parklands, QLD 4215, Australia
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59
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Slow-Wave Activity in the S1HL Cortex Is Contributed by Different Layer-Specific Field Potential Sources during Development. J Neurosci 2019; 39:8900-8915. [PMID: 31548234 PMCID: PMC6832678 DOI: 10.1523/jneurosci.1212-19.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 08/06/2019] [Accepted: 08/27/2019] [Indexed: 01/12/2023] Open
Abstract
Spontaneous correlated activity in cortical columns is critical for postnatal circuit refinement. We used spatial discrimination techniques to explore the late maturation of synaptic pathways through the laminar distribution of the field potential (FP) generators underlying spontaneous and evoked activities of the S1HL cortex in juvenile (P14-P16) and adult anesthetized rats. Juveniles exhibit an intermittent FP pattern resembling Up/Down states in adults, but with much reduced power and different laminar distribution. Whereas FPs in active periods are dominated by a layer VI generator in juveniles, in adults a developing multipart generator takes over, displaying current sinks in middle layers (III-V). The blockade of excitatory transmission in upper and middle layers of adults recovered the juvenile-like FP profiles. In addition to the layer VI generator, a gamma-specific generator in supragranular layers was the same in both age groups. While searching for dynamical coupling among generators in juveniles we found significant cross-correlation in ∼one-half of the tested pairs, whereas excessive coherence hindered their efficient separation in adults. Also, potentials evoked by tactile and electrical stimuli showed different short-latency dipoles between the two age groups, and the juveniles lacked the characteristic long latency UP state currents in middle layers. In addition, the mean firing rate of neurons was lower in juveniles. Thus, cortical FPs originate from different intra-columnar segments as they become active postnatally. We suggest that although some cortical segments are active early postnatally, a functional sensory-motor control relies on a delayed maturation and network integration of synaptic connections in middle layers.SIGNIFICANCE STATEMENT Early postnatal activity in the rodent cortex is mostly endogenous, whereas it becomes driven by peripheral input at later stages. The precise schedule for the maturation of synaptic pathways is largely unknown. We explored this in the somatosensory hindlimb cortex at an age when animals begin to use their limbs by uncovering the laminar distribution of the field potential generators underlying the dominant delta waves in juveniles and adults. Our results suggest that field potentials are mostly generated by a pathway in deep layers, whereas other pathways mature later in middle layers and take over in adults. We suggest that a functional sensory-motor control relies on a delayed maturation and network integration of synaptic connections in middle layers.
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60
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Byczkowicz N, Eshra A, Montanaro J, Trevisiol A, Hirrlinger J, Kole MHP, Shigemoto R, Hallermann S. HCN channel-mediated neuromodulation can control action potential velocity and fidelity in central axons. eLife 2019; 8:e42766. [PMID: 31496517 PMCID: PMC6733576 DOI: 10.7554/elife.42766] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2018] [Accepted: 08/13/2019] [Indexed: 12/31/2022] Open
Abstract
Hyperpolarization-activated cyclic-nucleotide-gated (HCN) channels control electrical rhythmicity and excitability in the heart and brain, but the function of HCN channels at the subcellular level in axons remains poorly understood. Here, we show that the action potential conduction velocity in both myelinated and unmyelinated central axons can be bidirectionally modulated by a HCN channel blocker, cyclic adenosine monophosphate (cAMP), and neuromodulators. Recordings from mouse cerebellar mossy fiber boutons show that HCN channels ensure reliable high-frequency firing and are strongly modulated by cAMP (EC50 40 µM; estimated endogenous cAMP concentration 13 µM). In addition, immunogold-electron microscopy revealed HCN2 as the dominating subunit in cerebellar mossy fibers. Computational modeling indicated that HCN2 channels control conduction velocity primarily by altering the resting membrane potential and are associated with significant metabolic costs. These results suggest that the cAMP-HCN pathway provides neuromodulators with an opportunity to finely tune energy consumption and temporal delays across axons in the brain.
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Affiliation(s)
- Niklas Byczkowicz
- Carl-Ludwig-Institute for Physiology, Medical FacultyUniversity LeipzigLeipzigGermany
| | - Abdelmoneim Eshra
- Carl-Ludwig-Institute for Physiology, Medical FacultyUniversity LeipzigLeipzigGermany
| | | | - Andrea Trevisiol
- Department of NeurogeneticsMax-Planck-Institute for Experimental MedicineGöttingenGermany
| | - Johannes Hirrlinger
- Carl-Ludwig-Institute for Physiology, Medical FacultyUniversity LeipzigLeipzigGermany
- Department of NeurogeneticsMax-Planck-Institute for Experimental MedicineGöttingenGermany
| | - Maarten HP Kole
- Department of Axonal Signaling, Netherlands Institute for NeuroscienceRoyal Netherlands Academy of Arts and SciencesAmsterdamNetherlands
- Cell Biology, Faculty of ScienceUniversity of UtrechtPadualaanNetherlands
| | - Ryuichi Shigemoto
- Institute of Science and Technology Austria (IST Austria)KlosterneuburgAustria
| | - Stefan Hallermann
- Carl-Ludwig-Institute for Physiology, Medical FacultyUniversity LeipzigLeipzigGermany
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61
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Kato D, Wake H, Lee PR, Tachibana Y, Ono R, Sugio S, Tsuji Y, Tanaka YH, Tanaka YR, Masamizu Y, Hira R, Moorhouse AJ, Tamamaki N, Ikenaka K, Matsukawa N, Fields RD, Nabekura J, Matsuzaki M. Motor learning requires myelination to reduce asynchrony and spontaneity in neural activity. Glia 2019; 68:193-210. [PMID: 31465122 PMCID: PMC6899965 DOI: 10.1002/glia.23713] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 07/23/2019] [Accepted: 08/12/2019] [Indexed: 12/21/2022]
Abstract
Myelination increases the conduction velocity in long‐range axons and is prerequisite for many brain functions. Impaired myelin regulation or impairment of myelin itself is frequently associated with deficits in learning and cognition in neurological and psychiatric disorders. However, it has not been revealed what perturbation of neural activity induced by myelin impairment causes learning deficits. Here, we measured neural activity in the motor cortex during motor learning in transgenic mice with a subtle impairment of their myelin. This deficit in myelin impaired motor learning, and was accompanied by a decrease in the amplitude of movement‐related activity and an increase in the frequency of spontaneous activity. Thalamocortical axons showed variability in axonal conduction with a large spread in the timing of postsynaptic cortical responses. Repetitive pairing of forelimb movements with optogenetic stimulation of thalamocortical axon terminals restored motor learning. Thus, myelin regulation helps to maintain the synchrony of cortical spike‐time arrivals through long‐range axons, facilitating the propagation of the information required for learning. Our results revealed the pathological neuronal circuit activity with impaired myelin and suggest the possibility that pairing of noninvasive brain stimulation with relevant behaviors may ameliorate cognitive and behavioral abnormalities in diseases with impaired myelination.
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Affiliation(s)
- Daisuke Kato
- Division of Homeostatic Development, National Institute for Physiological Sciences, Okazaki, Japan.,Division of Brain Circuits, National Institute for Basic Biology, Okazaki, Aichi, Japan.,Department of Neurology, Graduate School of Medicine, Nagoya City University, Nagoya, Japan.,Division of System Neuroscience, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Hiroaki Wake
- Division of Homeostatic Development, National Institute for Physiological Sciences, Okazaki, Japan.,Division of Brain Circuits, National Institute for Basic Biology, Okazaki, Aichi, Japan.,Division of System Neuroscience, Kobe University Graduate School of Medicine, Kobe, Japan.,Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency, Saitama, Japan.,Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Saitama, Japan
| | - Philip R Lee
- Section on Nervous System Development and Plasticity, National Institutes of Health, National Institute of Child Health and Human Development, Bethesda, Maryland
| | - Yoshihisa Tachibana
- Division of System Neuroscience, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Riho Ono
- Division of System Neuroscience, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Shouta Sugio
- Division of System Neuroscience, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Yukio Tsuji
- Division of System Neuroscience, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Yasuyo H Tanaka
- Division of Brain Circuits, National Institute for Basic Biology, Okazaki, Aichi, Japan.,Department of Physiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Yasuhiro R Tanaka
- Division of Brain Circuits, National Institute for Basic Biology, Okazaki, Aichi, Japan.,Department of Physiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Yoshito Masamizu
- Division of Brain Circuits, National Institute for Basic Biology, Okazaki, Aichi, Japan.,Department of Physiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Riichiro Hira
- Division of Brain Circuits, National Institute for Basic Biology, Okazaki, Aichi, Japan
| | - Andrew J Moorhouse
- Department of Physiology, School of Medical Sciences, The University of New South Wales, Sydney, Australia
| | - Nobuaki Tamamaki
- Department of Morphological Neural Science, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
| | - Kazuhiro Ikenaka
- Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, Okazaki, Japan
| | - Noriyuki Matsukawa
- Department of Neurology, Graduate School of Medicine, Nagoya City University, Nagoya, Japan
| | - R Douglas Fields
- Section on Nervous System Development and Plasticity, National Institutes of Health, National Institute of Child Health and Human Development, Bethesda, Maryland
| | - Junichi Nabekura
- Division of Homeostatic Development, National Institute for Physiological Sciences, Okazaki, Japan.,Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Saitama, Japan.,School of Life Science, The Graduate School for Advanced Study, Hayama, Japan
| | - Masanori Matsuzaki
- Division of Brain Circuits, National Institute for Basic Biology, Okazaki, Aichi, Japan.,Department of Physiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.,Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Saitama, Japan.,School of Life Science, The Graduate School for Advanced Study, Hayama, Japan
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62
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Redlich MJ, Lim H. A Method to Measure Myeloarchitecture of the Murine Cerebral Cortex in vivo and ex vivo by Intrinsic Third-Harmonic Generation. Front Neuroanat 2019; 13:65. [PMID: 31293394 PMCID: PMC6606705 DOI: 10.3389/fnana.2019.00065] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 06/11/2019] [Indexed: 11/13/2022] Open
Abstract
A new label-free method is presented for measuring myeloarchitecture of the murine cerebral cortex in vivo and ex vivo. Growing evidence suggests that cortical myelination plays significant roles in neuronal plasticity and pathologies, such as multiple sclerosis (MS), but illuminating the mechanism requires longitudinal imaging of the same brains. Here we demonstrate imaging unlabeled myelinated fibers in a live mouse brain by third-harmonic generation (THG). Contrary to other label-free microscopies based on reflectance, fibers of all orientations could be visualized, i.e., radial and tangential to the pia, which is suitable for revealing the three-dimensional connectivity. The depth of THG imaging in an intact brain was approximately 200 μm, so the network of myelinated fibers could be captured into layers 2/3 in vivo. THG provides a novel base for reconstruction of morphology. Semi-automatic tracing of THG-positive axons unraveled the depth-dependent distribution of the myelin lattice. Finally, a unique light property of THG was exploited for the estimation of the g-ratio. The demonstrated THG morphometry of the length density, orientation, and sheath thickness of cortical myelin could be useful for elucidating its function and how it is modulated during learning and disease.
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Affiliation(s)
- Michael J Redlich
- Department of Physics and Astronomy, Hunter College and the Graduate Center of the City University of New York, New York, NY, United States
| | - Hyungsik Lim
- Department of Physics and Astronomy, Hunter College and the Graduate Center of the City University of New York, New York, NY, United States
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63
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Murphy E. No Country for Oldowan Men: Emerging Factors in Language Evolution. Front Psychol 2019; 10:1448. [PMID: 31275219 PMCID: PMC6594215 DOI: 10.3389/fpsyg.2019.01448] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 06/06/2019] [Indexed: 01/14/2023] Open
Abstract
Language evolution has long been researched. I will review a number of broad, emerging research directions which arguably have the potential to contribute to our understanding of language evolution. Emerging topics in genomics and neurolinguistics are explored, and human-specific levels of braincase globularity - and the broader process of self-domestication within which globularity seems capable of being encapsulated - will be argued to be the central pillars of any satisfactory and interdisciplinary model of language evolution.
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Affiliation(s)
- Elliot Murphy
- Division of Psychology and Language Sciences, University College London, London, United Kingdom
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64
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Roberts JA, Gollo LL, Abeysuriya RG, Roberts G, Mitchell PB, Woolrich MW, Breakspear M. Metastable brain waves. Nat Commun 2019; 10:1056. [PMID: 30837462 PMCID: PMC6401142 DOI: 10.1038/s41467-019-08999-0] [Citation(s) in RCA: 86] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Accepted: 02/04/2019] [Indexed: 12/24/2022] Open
Abstract
Traveling patterns of neuronal activity-brain waves-have been observed across a breadth of neuronal recordings, states of awareness, and species, but their emergence in the human brain lacks a firm understanding. Here we analyze the complex nonlinear dynamics that emerge from modeling large-scale spontaneous neural activity on a whole-brain network derived from human tractography. We find a rich array of three-dimensional wave patterns, including traveling waves, spiral waves, sources, and sinks. These patterns are metastable, such that multiple spatiotemporal wave patterns are visited in sequence. Transitions between states correspond to reconfigurations of underlying phase flows, characterized by nonlinear instabilities. These metastable dynamics accord with empirical data from multiple imaging modalities, including electrical waves in cortical tissue, sequential spatiotemporal patterns in resting-state MEG data, and large-scale waves in human electrocorticography. By moving the study of functional networks from a spatially static to an inherently dynamic (wave-like) frame, our work unifies apparently diverse phenomena across functional neuroimaging modalities and makes specific predictions for further experimentation.
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Affiliation(s)
- James A Roberts
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, 4006, Australia.
- Centre for Integrative Brain Function, QIMR Berghofer Medical Research Institute, Brisbane, QLD, 4006, Australia.
| | - Leonardo L Gollo
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, 4006, Australia
- Centre for Integrative Brain Function, QIMR Berghofer Medical Research Institute, Brisbane, QLD, 4006, Australia
| | - Romesh G Abeysuriya
- Oxford Centre for Human Brain Activity (OHBA), Wellcome Centre for Integrative NeuroImaging, Department of Psychiatry, University of Oxford, Oxford, OX3 7JX, UK
| | - Gloria Roberts
- School of Psychiatry, University of New South Wales, Sydney, NSW, 2052, Australia
- Black Dog Institute, Prince of Wales Hospital, Hospital Road, Randwick, NSW, 2031, Australia
| | - Philip B Mitchell
- School of Psychiatry, University of New South Wales, Sydney, NSW, 2052, Australia
- Black Dog Institute, Prince of Wales Hospital, Hospital Road, Randwick, NSW, 2031, Australia
| | - Mark W Woolrich
- Oxford Centre for Human Brain Activity (OHBA), Wellcome Centre for Integrative NeuroImaging, Department of Psychiatry, University of Oxford, Oxford, OX3 7JX, UK
| | - Michael Breakspear
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, 4006, Australia
- Centre for Integrative Brain Function, QIMR Berghofer Medical Research Institute, Brisbane, QLD, 4006, Australia
- Metro North Mental Health Service, Royal Brisbane and Women's Hospital, Brisbane, QLD, 4029, Australia
- Hunter Medical Research Institute, University of Newcastle, Newcastle, NSW, 2305, Australia
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65
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Sun YJ, Liu BH, Tao HW, Zhang LI. Selective Strengthening of Intracortical Excitatory Input Leads to Receptive Field Refinement during Auditory Cortical Development. J Neurosci 2019; 39:1195-1205. [PMID: 30587538 PMCID: PMC6381237 DOI: 10.1523/jneurosci.2492-18.2018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 11/17/2018] [Accepted: 12/07/2018] [Indexed: 11/21/2022] Open
Abstract
In the primary auditory cortex (A1) of rats, refinement of excitatory input to layer (L)4 neurons contributes to the sharpening of their frequency selectivity during postnatal development. L4 neurons receive both feedforward thalamocortical and recurrent intracortical inputs, but how potential developmental changes of each component can account for the sharpening of excitatory input tuning remains unclear. By combining in vivo whole-cell recording and pharmacological silencing of cortical spiking in young rats of both sexes, we examined developmental changes at three hierarchical stages: output of auditory thalamic neurons, thalamocortical input and recurrent excitatory input to an A1 L4 neuron. In the thalamus, the tonotopic map matured with an expanded range of frequency representations, while the frequency tuning of output responses was unchanged. On the other hand, the tuning shape of both thalamocortical and intracortical excitatory inputs to a L4 neuron became sharpened. In particular, the intracortical input became better tuned than thalamocortical excitation. Moreover, the weight of intracortical excitation around the optimal frequency was selectively strengthened, resulting in a dominant role of intracortical excitation in defining the total excitatory input tuning. Our modeling work further demonstrates that the frequency-selective strengthening of local recurrent excitatory connections plays a major role in the refinement of excitatory input tuning of L4 neurons.SIGNIFICANCE STATEMENT During postnatal development, sensory cortex undergoes functional refinement, through which the size of sensory receptive field is reduced. In the rat primary auditory cortex, such refinement in layer (L)4 is mainly attributed to improved selectivity of excitatory input a L4 neuron receives. In this study, we further examined three stages along the hierarchical neural pathway where excitatory input refinement might occur. We found that developmental refinement takes place at both thalamocortical and intracortical circuit levels, but not at the thalamic output level. Together with modeling results, we revealed that the optimal-frequency-selective strengthening of intracortical excitation plays a dominant role in the refinement of excitatory input tuning.
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Affiliation(s)
- Yujiao J Sun
- Zilkha Neurogenetic Institute
- Graduate Program in Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, California 90089
| | - Bao-Hua Liu
- Zilkha Neurogenetic Institute
- Graduate Program in Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, California 90089
| | - Huizhong W Tao
- Zilkha Neurogenetic Institute,
- Department of Physiology and Neuroscience, and
| | - Li I Zhang
- Zilkha Neurogenetic Institute,
- Department of Physiology and Neuroscience, and
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66
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Outgrowing seizures in Childhood Absence Epilepsy: time delays and bistability. J Comput Neurosci 2019; 46:197-209. [PMID: 30737596 DOI: 10.1007/s10827-019-00711-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 12/14/2018] [Accepted: 01/29/2019] [Indexed: 10/27/2022]
Abstract
We formulate a conductance-based model for a 3-neuron motif associated with Childhood Absence Epilepsy (CAE). The motif consists of neurons from the thalamic relay (TC) and reticular nuclei (RT) and the cortex (CT). We focus on a genetic defect common to the mouse homolog of CAE which is associated with loss of GABAA receptors on the TC neuron, and the fact that myelination of axons as children age can increase the conduction velocity between neurons. We show the combination of low GABAA mediated inhibition of TC neurons and the long corticothalamic loop delay gives rise to a variety of complex dynamics in the motif, including bistability. This bistability disappears as the corticothalamic conduction delay shortens even though GABAA activity remains impaired. Thus the combination of deficient GABAA activity and changing axonal myelination in the corticothalamic loop may be sufficient to account for the clinical course of CAE.
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67
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Wilson D, Faramarzi S, Moehlis J, Tinsley MR, Showalter K. Synchronization of heterogeneous oscillator populations in response to weak and strong coupling. CHAOS (WOODBURY, N.Y.) 2018; 28:123114. [PMID: 30599520 DOI: 10.1063/1.5049475] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2018] [Accepted: 11/19/2018] [Indexed: 06/09/2023]
Abstract
Synchronous behavior of a population of chemical oscillators is analyzed in the presence of both weak and strong coupling. In each case, we derive upper bounds on the critical coupling strength which are valid for arbitrary populations of nonlinear, heterogeneous oscillators. For weak perturbations, infinitesimal phase response curves are used to characterize the response to coupling, and graph theoretical techniques are used to predict synchronization. In the strongly perturbed case, we observe a phase dependent perturbation threshold required to elicit an immediate spike and use this behavior for our analytical predictions. Resulting upper bounds on the critical coupling strength agree well with our experimental observations and numerical simulations. Furthermore, important system parameters which determine synchronization are different in the weak and strong coupling regimes. Our results point to new strategies by which limit cycle oscillators can be studied when the applied perturbations become strong enough to immediately reset the phase.
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Affiliation(s)
- Dan Wilson
- Department of Electrical Engineering and Computer Science, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Sadegh Faramarzi
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506-6045, USA
| | - Jeff Moehlis
- Department of Mechanical Engineering, University of California, Santa Barbara, California 93106, USA
| | - Mark R Tinsley
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506-6045, USA
| | - Kenneth Showalter
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506-6045, USA
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68
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Chorghay Z, Káradóttir RT, Ruthazer ES. White Matter Plasticity Keeps the Brain in Tune: Axons Conduct While Glia Wrap. Front Cell Neurosci 2018; 12:428. [PMID: 30519159 PMCID: PMC6251003 DOI: 10.3389/fncel.2018.00428] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2018] [Accepted: 10/30/2018] [Indexed: 12/28/2022] Open
Abstract
Precise timing of neuronal inputs is crucial for brain circuit function and development, where it contributes critically to experience-dependent plasticity. Myelination therefore provides an important adaptation mechanism for vertebrate circuits. Despite its importance to circuit activity, the interplay between neuronal activity and myelination has yet to be fully elucidated. In recent years, significant attention has been devoted to uncovering and explaining the phenomenon of white matter (WM) plasticity. Here, we summarize some of the critical evidence for modulation of the WM by neuronal activity, ranging from human diffusion tensor imaging (DTI) studies to experiments in animal models. These experiments reveal activity-dependent changes in the differentiation and proliferation of the oligodendrocyte lineage, and in the critical properties of the myelin sheaths. We discuss the implications of such changes for synaptic function and plasticity, and present the underlying mechanisms of neuron–glia communication, with a focus on glutamatergic signaling and the axomyelinic synapse. Finally, we examine evidence that myelin plasticity may be subject to critical periods. Taken together, the present review aims to provide insights into myelination in the context of brain circuit formation and function, emphasizing the bidirectional interplay between neurons and myelinating glial cells to better inform future investigations of nervous system plasticity.
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Affiliation(s)
- Zahraa Chorghay
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Ragnhildur Thóra Káradóttir
- Department of Veterinary Medicine, Wellcome Trust - Medical Research Council Stem Cell Institute, University of Cambridge, Cambridge, United Kingdom
| | - Edward S Ruthazer
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
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69
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Cabessa J, Villa AEP. Attractor dynamics of a Boolean model of a brain circuit controlled by multiple parameters. CHAOS (WOODBURY, N.Y.) 2018; 28:106318. [PMID: 30384642 DOI: 10.1063/1.5042312] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 08/29/2018] [Indexed: 06/08/2023]
Abstract
Studies of Boolean recurrent neural networks are briefly introduced with an emphasis on the attractor dynamics determined by the sequence of distinct attractors observed in the limit cycles. We apply this framework to a simplified model of the basal ganglia-thalamocortical circuit where each brain area is represented by a "neuronal" node in a directed graph. Control parameters ranging from neuronal excitability that affects all cells to targeted local connections modified by a new adaptive plasticity rule, and the regulation of the interactive feedback affecting the external input stream of information, allow the network dynamics to switch between stable domains delimited by highly discontinuous boundaries and reach very high levels of complexity with specific configurations. The significance of this approach with regard to brain circuit studies is briefly discussed.
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Affiliation(s)
- Jérémie Cabessa
- Laboratory of Mathematical Economics (LEMMA), Université Paris 2-Panthéon-Assas, 75005 Paris, France
| | - Alessandro E P Villa
- Neuroheuristic Research Group, University of Lausanne, CH-1015 Lausanne, Switzerland
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70
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Myelination of Axons Corresponds with Faster Transmission Speed in the Prefrontal Cortex of Developing Male Rats. eNeuro 2018; 5:eN-NWR-0203-18. [PMID: 30225359 PMCID: PMC6140121 DOI: 10.1523/eneuro.0203-18.2018] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 08/13/2018] [Accepted: 08/14/2018] [Indexed: 12/31/2022] Open
Abstract
Myelination of prefrontal circuits during adolescence is thought to lead to enhanced cognitive processing and improved behavioral control. However, while standard neuroimaging techniques commonly used in human and animal studies can measure large white matter bundles and residual conduction speed, they cannot directly measure myelination of individual axons or how fast electrical signals travel along these axons. Here we focused on a specific population of prefrontal axons to directly measure conduction velocity and myelin microstructure in developing male rats. An in vitro electrophysiological approach enabled us to isolate monosynaptic projections from the anterior branches of the corpus callosum (corpus callosum-forceps minor, CCFM) to the anterior cingulate subregion of the medial prefrontal cortex (Cg1) and to measure the speed and direction of action potentials propagating along these axons. We found that a large number of axons projecting from the CCFM to neurons in Layer V of Cg1 are ensheathed with myelin between pre-adolescence [postnatal day (PD)15] and mid-adolescence (PD43). This robust increase in axonal myelination is accompanied by a near doubling of transmission speed. As there was no age difference in the diameter of these axons, myelin is likely the driving force behind faster transmission of electrical signals in older animals. These developmental changes in axonal microstructure and physiology may extend to other axonal populations as well, and could underlie some of the improvements in cognitive processing between childhood and adolescence.
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71
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Hyperintense sensorimotor T1 spin echo MRI is associated with brainstem abnormality in chronic fatigue syndrome. NEUROIMAGE-CLINICAL 2018; 20:102-109. [PMID: 30497131 PMCID: PMC6309570 DOI: 10.1016/j.nicl.2018.07.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 06/29/2018] [Accepted: 07/10/2018] [Indexed: 01/08/2023]
Abstract
We recruited 43 Chronic Fatigue Syndrome (CFS) subjects who met Fukuda criteria and 27 healthy controls and performed 3T MRI T1 and T2 weighted spin-echo (T1wSE and T2wSE) scans. T1wSE signal follows T1 relaxation rate (1/T1 relaxation time) and responds to myelin and iron (ferritin) concentrations. We performed MRI signal level group comparisons with SPM12. Spatial normalization after segmentation was performed using T2wSE scans and applied to the coregistered T1wSE scans. After global signal-level normalization of individual scans, the T1wSE group comparison detected decreased signal-levels in CFS in a brainstem region (cluster-based inference controlled for family wise error rate, PFWE= 0.002), and increased signal-levels in large bilateral clusters in sensorimotor cortex white matter (cluster PFWE < 0.0001). Moreover, the brainstem T1wSE values were negatively correlated with the sensorimotor values for both CFS (R2 = 0.31, P = 0.00007) and healthy controls (R2 = 0.34, P = 0.0009), and the regressions were co-linear. This relationship, previously unreported in either healthy controls or CFS, in view of known thalamic projection-fibre plasticity, suggests brainstem conduction deficits in CFS may stimulate the upregulation of myelin in the sensorimotor cortex to maintain brainstem - sensorimotor connectivity. VBM did not find group differences in regional grey matter or white matter volumes. We argued that increased T1wSE observed in sensorimotor WM in CFS indicates increased myelination which is a regulatory response to deficits in the brainstem although the causality cannot be tested in this study. Altered brainstem myelin may have broad consequences for cerebral function and should be a focus of future research.
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72
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Higgins I, Stringer S, Schnupp J. A Computational Account of the Role of Cochlear Nucleus and Inferior Colliculus in Stabilizing Auditory Nerve Firing for Auditory Category Learning. Neural Comput 2018; 30:1801-1829. [PMID: 29652586 DOI: 10.1162/neco_a_01085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
It is well known that auditory nerve (AN) fibers overcome bandwidth limitations through the volley principle, a form of multiplexing. What is less well known is that the volley principle introduces a degree of unpredictability into AN neural firing patterns that may be affecting even simple stimulus categorization learning. We use a physiologically grounded, unsupervised spiking neural network model of the auditory brain with spike time dependent plasticity learning to demonstrate that plastic auditory cortex is unable to learn even simple auditory object categories when exposed to the raw AN firing input without subcortical preprocessing. We then demonstrate the importance of nonplastic subcortical preprocessing within the cochlear nucleus and the inferior colliculus for stabilizing and denoising AN responses. Such preprocessing enables the plastic auditory cortex to learn efficient robust representations of the auditory object categories. The biological realism of our model makes it suitable for generating neurophysiologically testable hypotheses.
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Affiliation(s)
- Irina Higgins
- Department of Experimental Psychology, University of Oxford, Oxford, OX2 6GG, U.K.
| | - Simon Stringer
- Department of Experimental Psychology, University of Oxford, Oxford, OX2 6GG, U.K.
| | - Jan Schnupp
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, OX1 3QX, U.K.
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73
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Lifelong cortical myelin plasticity and age-related degeneration in the live mammalian brain. Nat Neurosci 2018; 21:683-695. [PMID: 29556031 PMCID: PMC5920745 DOI: 10.1038/s41593-018-0120-6] [Citation(s) in RCA: 250] [Impact Index Per Article: 41.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 02/05/2018] [Indexed: 01/30/2023]
Abstract
Axonal myelin increases neural processing speed and efficiency. It is unknown whether patterns of myelin distribution are fixed or whether myelinating oligodendrocytes are continually generated in adulthood and maintain the capacity for structural remodeling. Using high-resolution, intravital label-free and fluorescence optical imaging in mouse cortex, we demonstrate lifelong oligodendrocyte generation occurring in parallel with structural plasticity of individual myelin internodes. Continuous internode formation occurred on both partially myelinated and unmyelinated axons, and the total myelin coverage along individual axons progressed up to two years of age. After peak myelination, gradual oligodendrocyte death and myelin degeneration in aging were associated with pronounced internode loss and myelin debris accumulation within microglia. Thus, cortical myelin remodeling is protracted throughout life, potentially playing critical roles in neuronal network homeostasis. The gradual loss of internodes and myelin degeneration in aging could contribute significantly to brain pathogenesis.
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74
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The cortical focus in childhood absence epilepsy; evidence from nonlinear analysis of scalp EEG recordings. Clin Neurophysiol 2018; 129:602-617. [DOI: 10.1016/j.clinph.2017.11.029] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 11/05/2017] [Accepted: 11/29/2017] [Indexed: 11/19/2022]
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75
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Ouhaz Z, Fleming H, Mitchell AS. Cognitive Functions and Neurodevelopmental Disorders Involving the Prefrontal Cortex and Mediodorsal Thalamus. Front Neurosci 2018; 12:33. [PMID: 29467603 PMCID: PMC5808198 DOI: 10.3389/fnins.2018.00033] [Citation(s) in RCA: 88] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 01/15/2018] [Indexed: 11/13/2022] Open
Abstract
The mediodorsal nucleus of the thalamus (MD) has been implicated in executive functions (such as planning, cognitive control, working memory, and decision-making) because of its significant interconnectivity with the prefrontal cortex (PFC). Yet, whilst the roles of the PFC have been extensively studied, how the MD contributes to these cognitive functions remains relatively unclear. Recently, causal evidence in monkeys has demonstrated that in everyday tasks involving rapid updating (e.g., while learning something new, making decisions, or planning the next move), the MD and frontal cortex are working in close partnership. Furthermore, researchers studying the MD in rodents have been able to probe the underlying mechanisms of this relationship to give greater insights into how the frontal cortex and MD might interact during the performance of these essential tasks. This review summarizes the circuitry and known neuromodulators of the MD, and considers the most recent behavioral, cognitive, and neurophysiological studies conducted in monkeys and rodents; in total, this evidence demonstrates that MD makes a critical contribution to cognitive functions. We propose that communication occurs between the MD and the frontal cortex in an ongoing, fluid manner during rapid cognitive operations, via the means of efference copies of messages passed through transthalamic routes; the conductance of these messages may be modulated by other brain structures interconnected to the MD. This is similar to the way in which other thalamic structures have been suggested to carry out forward modeling associated with rapid motor responding and visual processing. Given this, and the marked thalamic pathophysiology now identified in many neuropsychiatric disorders, we suggest that changes in the different subdivisions of the MD and their interconnections with the cortex could plausibly give rise to a number of the otherwise disparate symptoms (including changes to olfaction and cognitive functioning) that are associated with many different neuropsychiatric disorders. In particular, we will focus here on the cognitive symptoms of schizophrenia and suggest testable hypotheses about how changes to MD-frontal cortex interactions may affect cognitive processes in this disorder.
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Affiliation(s)
- Zakaria Ouhaz
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom
| | - Hugo Fleming
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom
| | - Anna S Mitchell
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom
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76
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Hartung H, Cichon N, De Feo V, Riemann S, Schildt S, Lindemann C, Mulert C, Gogos JA, Hanganu-Opatz IL. From Shortage to Surge: A Developmental Switch in Hippocampal-Prefrontal Coupling in a Gene-Environment Model of Neuropsychiatric Disorders. Cereb Cortex 2018; 26:4265-4281. [PMID: 27613435 PMCID: PMC5066837 DOI: 10.1093/cercor/bhw274] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 08/10/2016] [Indexed: 12/21/2022] Open
Abstract
Cognitive deficits represent a major burden of neuropsychiatric disorders and result in part from abnormal communication within hippocampal–prefrontal circuits. While it has been hypothesized that this network dysfunction arises during development, long before the first clinical symptoms, experimental evidence is still missing. Here, we show that pre-juvenile mice mimicking genetic and environmental risk factors of disease (dual-hit GE mice) have poorer recognition memory that correlates with augmented coupling by synchrony and stronger directed interactions between prefrontal cortex and hippocampus. The network dysfunction emerges already during neonatal development, yet it initially consists in a diminished hippocampal theta drive and consequently, a weaker and disorganized entrainment of local prefrontal circuits in discontinuous oscillatory activity in dual-hit GE mice when compared with controls. Thus, impaired maturation of functional communication within hippocampal–prefrontal networks switching from hypo- to hyper-coupling may represent a mechanism underlying the pathophysiology of cognitive deficits in neuropsychiatric disorders.
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Affiliation(s)
- Henrike Hartung
- Developmental Neurophysiology, Institute of Neuroanatomy, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany.,Laboratory of Neurobiology, Department of Biosciences, University of Helsinki, 00014 Helsinki, Finland
| | - Nicole Cichon
- Developmental Neurophysiology, Institute of Neuroanatomy, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Vito De Feo
- Developmental Neurophysiology, Institute of Neuroanatomy, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany.,Laboratory of Neural Computation, Center for Neuroscience and Cognitive Systems, Istituto Italiano di Tecnologia, 38068 Rovereto, Italy
| | - Stephanie Riemann
- Developmental Neurophysiology, Institute of Neuroanatomy, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany.,Current address: German Center for Neurodegenerative Diseases (DZNE), 39120 Magdeburg, Germany
| | - Sandra Schildt
- Developmental Neurophysiology, Institute of Neuroanatomy, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Christoph Lindemann
- Developmental Neurophysiology, Institute of Neuroanatomy, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Christoph Mulert
- Department of Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Joseph A Gogos
- Department of Neuroscience, Columbia University, New York, NY 10032, USA.,Department of Physiology, Columbia University, New York, NY 10032, USA
| | - Ileana L Hanganu-Opatz
- Developmental Neurophysiology, Institute of Neuroanatomy, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
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DNA damage-associated oligodendrocyte degeneration precedes amyloid pathology and contributes to Alzheimer's disease and dementia. Alzheimers Dement 2018; 14:664-679. [PMID: 29328926 DOI: 10.1016/j.jalz.2017.11.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 11/18/2017] [Accepted: 11/28/2017] [Indexed: 11/20/2022]
Abstract
INTRODUCTION In looking for novel non-amyloid-based etiologies for Alzheimer's disease, we explore the hypothesis that age-related myelin loss is an attractive explanation for age-associated cognitive decline and dementia. METHODS We performed a meta-analysis of data in the National Alzheimer's Coordinating Center database accompanied by quantitative histopathology of myelin and oligodendrocytes (OLs) in frontal cortices of 24 clinically characterized individuals. Pathological findings were further validated in an Alzheimer's disease mouse model and in culture. RESULTS Myelin lesions increased with cognitive impairment in an amyloid-independent fashion with signs of degeneration appearing before neuronal loss. Myelinating OLs in the gray matter showed greater vulnerability than those in white matter, and the degenerative changes correlated with evidence of DNA damage. Similar results were found in myelinating OL cultures where DNA damage caused aberrant OL cell cycle re-entry and death. DISCUSSION We present the first comprehensive analysis of the cell biology of early myelin loss in sporadic Alzheimer's disease.
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78
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Melie-Garcia L, Slater D, Ruef A, Sanabria-Diaz G, Preisig M, Kherif F, Draganski B, Lutti A. Networks of myelin covariance. Hum Brain Mapp 2017; 39:1532-1554. [PMID: 29271053 PMCID: PMC5873432 DOI: 10.1002/hbm.23929] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 12/02/2017] [Accepted: 12/11/2017] [Indexed: 01/05/2023] Open
Abstract
Networks of anatomical covariance have been widely used to study connectivity patterns in both normal and pathological brains based on the concurrent changes of morphometric measures (i.e., cortical thickness) between brain structures across subjects (Evans, ). However, the existence of networks of microstructural changes within brain tissue has been largely unexplored so far. In this article, we studied in vivo the concurrent myelination processes among brain anatomical structures that gathered together emerge to form nonrandom networks. We name these "networks of myelin covariance" (Myelin-Nets). The Myelin-Nets were built from quantitative Magnetization Transfer data-an in-vivo magnetic resonance imaging (MRI) marker of myelin content. The synchronicity of the variations in myelin content between anatomical regions was measured by computing the Pearson's correlation coefficient. We were especially interested in elucidating the effect of age on the topological organization of the Myelin-Nets. We therefore selected two age groups: Young-Age (20-31 years old) and Old-Age (60-71 years old) and a pool of participants from 48 to 87 years old for a Myelin-Nets aging trajectory study. We found that the topological organization of the Myelin-Nets is strongly shaped by aging processes. The global myelin correlation strength, between homologous regions and locally in different brain lobes, showed a significant dependence on age. Interestingly, we also showed that the aging process modulates the resilience of the Myelin-Nets to damage of principal network structures. In summary, this work sheds light on the organizational principles driving myelination and myelin degeneration in brain gray matter and how such patterns are modulated by aging.
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Affiliation(s)
- Lester Melie-Garcia
- LREN, Department of Clinical Neurosciences, Lausanne University Hospital (CHUV), Switzerland
| | - David Slater
- LREN, Department of Clinical Neurosciences, Lausanne University Hospital (CHUV), Switzerland
| | - Anne Ruef
- LREN, Department of Clinical Neurosciences, Lausanne University Hospital (CHUV), Switzerland
| | - Gretel Sanabria-Diaz
- LREN, Department of Clinical Neurosciences, Lausanne University Hospital (CHUV), Switzerland
| | - Martin Preisig
- Department of Psychiatry, Lausanne University Hospital (CHUV), Switzerland
| | - Ferath Kherif
- LREN, Department of Clinical Neurosciences, Lausanne University Hospital (CHUV), Switzerland
| | - Bogdan Draganski
- LREN, Department of Clinical Neurosciences, Lausanne University Hospital (CHUV), Switzerland.,Max-Planck-Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Antoine Lutti
- LREN, Department of Clinical Neurosciences, Lausanne University Hospital (CHUV), Switzerland
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80
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The temporal dynamics involved in object representation updating to predict change. PROGRESS IN BRAIN RESEARCH 2017; 236:269-285. [PMID: 29157416 DOI: 10.1016/bs.pbr.2017.06.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2023]
Abstract
The synchronization of cortically disparate neural assemblies at frequencies in the gamma-band range (30-70Hz) is considered to be involved in the perceptual organization of the environment. In support of this Elliott (2014) demonstrated improved detection of a target stimulus when this target was primed in a matrix that flickered at specific frequencies in the gamma-band range, each found to be separated by regular intervals which correspond with a 6.69Hz period. This can be explained in terms of the interaction of the stimulus (and stimulus-induced) rhythm with a slow endogenous theta rhythm. When the interaction is in phase between these rhythms and target presentation time is slightly ahead of the priming stimulus presentation, improved detection times are recorded indicating an anticipatory response. However, when these rhythms are out of phase and the target is presented during or slightly after priming stimulus presentation, improved responding also occurs, suggesting a retroactive response is facilitated. Research in the auditory domain supports these findings (Aksentijevic et al., 2011). The conclusions of this research suggest that synchronization of neural assemblies contributes to the temporal code necessary to facilitate representation updating in order to respond to a dynamic environment and anticipate the logical next event.
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81
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On Myelinated Axon Plasticity and Neuronal Circuit Formation and Function. J Neurosci 2017; 37:10023-10034. [PMID: 29046438 DOI: 10.1523/jneurosci.3185-16.2017] [Citation(s) in RCA: 128] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Revised: 08/31/2017] [Indexed: 12/28/2022] Open
Abstract
Studies of activity-driven nervous system plasticity have primarily focused on the gray matter. However, MRI-based imaging studies have shown that white matter, primarily composed of myelinated axons, can also be dynamically regulated by activity of the healthy brain. Myelination in the CNS is an ongoing process that starts around birth and continues throughout life. Myelin in the CNS is generated by oligodendrocytes and recent evidence has shown that many aspects of oligodendrocyte development and myelination can be modulated by extrinsic signals including neuronal activity. Because modulation of myelin can, in turn, affect several aspects of conduction, the concept has emerged that activity-regulated myelination represents an important form of nervous system plasticity. Here we review our increasing understanding of how neuronal activity regulates oligodendrocytes and myelinated axons in vivo, with a focus on the timing of relevant processes. We highlight the observations that neuronal activity can rapidly tune axonal diameter, promote re-entry of oligodendrocyte progenitor cells into the cell cycle, or drive their direct differentiation into oligodendrocytes. We suggest that activity-regulated myelin formation and remodeling that significantly change axonal conduction properties are most likely to occur over timescales of days to weeks. Finally, we propose that precise fine-tuning of conduction along already-myelinated axons may also be mediated by alterations to the axon itself. We conclude that future studies need to analyze activity-driven adaptations to both axons and their myelin sheaths to fully understand how myelinated axon plasticity contributes to neuronal circuit formation and function.
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82
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Ohshima M, Itami C, Kimura F. The α 2A -adrenoceptor suppresses excitatory synaptic transmission to both excitatory and inhibitory neurons in layer 4 barrel cortex. J Physiol 2017; 595:6923-6937. [PMID: 28948610 DOI: 10.1113/jp275142] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 09/22/2017] [Indexed: 12/11/2022] Open
Abstract
KEY POINTS The effects of noradrenaline on excitatory synaptic transmission to regular spiking (excitatory) cells as well as regular spiking non-pyramidal and fast spiking (both inhibitory) cells in cortical layer 4 were studied in thalamocortical slice preparations, focusing on vertical input from thalamus and layer 2/3 in the mouse barrel cortex. Excitatory synaptic responses were suppressed by noradrenaline. However, currents induced by iontophoretically applied glutamate were not suppressed. Further, paired pulse ratio and coefficient of variation analysis indicated the site of action was presynaptic. Pharmacological studies indicated that the suppression was mediated by the α2- adrenoceptor. Consistent with this, involvement of α2A -adrenoceptor activation in the synaptic suppression in excitatory and inhibitory cells was confirmed by the use of α2A -adrenoceptor knockout mice. ABSTRACT The mammalian neocortex is widely innervated by noradrenergic (NA) fibres from the locus coeruleus. To determine the effects of NA on vertical synaptic inputs to layer 4 (L4) cells from the ventrobasal thalamus and layer 2/3 (L2/3), thalamocortical slices were prepared and whole-cell recordings were made from L4 cells. Excitatory synaptic responses were evoked by electrical stimulation of the thalamus or L2/3 immediately above. Recorded cells were identified as regular spiking, regular spiking non-pyramidal or fast spiking cells through their firing patterns in response to current injections. NA suppressed (∼50% of control) excitatory vertical inputs to all cell types in a dose-dependent manner. The presynaptic site of action of NA was suggested by three independent studies. First, responses caused by iontophoretically applied glutamate were not suppressed by NA. Second, the paired pulse ratio was increased during NA suppression. Finally, a coefficient of variation (CV) analysis was performed and the resultant diagonal alignment of the ratio of CV-2 plotted against the ratio of the amplitude of postsynaptic responses suggests a presynaptic mechanism for the suppression. Experiments with phenylephrine (an α1 -agonist), prazosin (an α1 -antagonist), yohimbine (an α2 -antagonist) and propranolol (a β-antagonist) indicated that suppression was mediated by the α2 -adrenoceptor. To determine whether the α2A -adrenoceptor subtype was involved, α2A -adrenoceptor knockout mice were used. NA failed to suppress EPSCs in all cell types, suggesting an involvement of the α2A -adrenoceptor. Altogether, we concluded that NA suppresses vertical excitatory synaptic connections in L4 excitatory and inhibitory cells through the presynaptic α2A -adrenoceptor.
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Affiliation(s)
- Minoru Ohshima
- Department of Physiology, Kansai University of Health Sciences, Kumatori, 590-0482, Japan
| | - Chiaki Itami
- Department of Physiology, Faculty of Medicine, Saitama Medical University, Moroyama, Saitama, 350-0495, Japan
| | - Fumitaka Kimura
- Department of Molecular Neuroscience, Osaka University Graduate School of Medicine, Suita, 565-0871, Japan
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83
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de Faria O, Pama EAC, Evans K, Luzhynskaya A, Káradóttir RT. Neuroglial interactions underpinning myelin plasticity. Dev Neurobiol 2017; 78:93-107. [PMID: 28941015 DOI: 10.1002/dneu.22539] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 08/11/2017] [Accepted: 09/14/2017] [Indexed: 11/07/2022]
Abstract
The CNS is extremely responsive to an ever-changing environment. Studies of neural circuit plasticity focus almost exclusively on functional and structural changes of neuronal synapses. In recent years, however, myelin plasticity has emerged as a potential modulator of neuronal networks. Myelination of previously unmyelinated axons and changes in the structure of myelin on already-myelinated axons (similar to changes in internode number and length or myelin thickness or geometry of the nodal area) can in theory have significant effects on the function of neuronal networks. In this article, the authors review the current evidence for myelin changes occurring in the adult CNS, highlight some potential underlying mechanisms of how neuronal activity may regulate myelin changes, and explore the similarities between neuronal and myelin plasticity. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 78: 93-107, 2018.
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Affiliation(s)
- Omar de Faria
- Wellcome Trust-Medical Research Council Cambridge Stem Cell Institute & Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Ewa Anastazia Claudia Pama
- Wellcome Trust-Medical Research Council Cambridge Stem Cell Institute & Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Kimberley Evans
- Wellcome Trust-Medical Research Council Cambridge Stem Cell Institute & Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Aryna Luzhynskaya
- Wellcome Trust-Medical Research Council Cambridge Stem Cell Institute & Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Ragnhildur Thóra Káradóttir
- Wellcome Trust-Medical Research Council Cambridge Stem Cell Institute & Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
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84
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Vyshedskiy A, Mahapatra S, Dunn R. Linguistically deprived children: meta-analysis of published research underlines the importance of early syntactic language use for normal brain development. RESEARCH IDEAS AND OUTCOMES 2017. [DOI: 10.3897/rio.3.e20696] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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85
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Danet L, Pariente J, Eustache P, Raposo N, Sibon I, Albucher JF, Bonneville F, Péran P, Barbeau EJ. Medial thalamic stroke and its impact on familiarity and recollection. eLife 2017; 6:28141. [PMID: 28837019 PMCID: PMC5595429 DOI: 10.7554/elife.28141] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 08/21/2017] [Indexed: 11/13/2022] Open
Abstract
Models of recognition memory have postulated that the mammillo-thalamic tract (MTT)/anterior thalamic nucleus (AN) complex would be critical for recollection while the Mediodorsal nucleus (MD) of the thalamus would support familiarity and indirectly also be involved in recollection (Aggleton et al., 2011). 12 patients with left thalamic stroke underwent a neuropsychological assessment, three verbal recognition memory tasks assessing familiarity and recollection each using different procedures and a high-resolution structural MRI. Patients showed poor recollection on all three tasks. In contrast, familiarity was spared in each task. No patient had significant AN lesions. Critically, a subset of 5 patients had lesions of the MD without lesions of the MTT. They also showed impaired recollection but preserved familiarity. Recollection is therefore impaired following MD damage, but familiarity is not. This suggests that models of familiarity, which assign a critical role to the MD, should be reappraised.
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Affiliation(s)
- Lola Danet
- Toulouse NeuroImaging Center, Université de Toulouse, Inserm, Toulouse, France.,Brain and Cognition Research Centre, CNRS, University of Toulouse Paul Sabatier, Toulouse, France.,Neurology Department, CHU Toulouse Purpan, Toulouse, France
| | - Jérémie Pariente
- Toulouse NeuroImaging Center, Université de Toulouse, Inserm, Toulouse, France.,Neurology Department, CHU Toulouse Purpan, Toulouse, France
| | - Pierre Eustache
- Toulouse NeuroImaging Center, Université de Toulouse, Inserm, Toulouse, France
| | - Nicolas Raposo
- Toulouse NeuroImaging Center, Université de Toulouse, Inserm, Toulouse, France.,Neurology Department, CHU Toulouse Purpan, Toulouse, France
| | - Igor Sibon
- Department of Diagnostic and Therapeutic Neuroimaging, University of Bordeaux, Bordeaux University Hospital, Bordeaux, France
| | - Jean-François Albucher
- Toulouse NeuroImaging Center, Université de Toulouse, Inserm, Toulouse, France.,Neurology Department, CHU Toulouse Purpan, Toulouse, France
| | - Fabrice Bonneville
- Toulouse NeuroImaging Center, Université de Toulouse, Inserm, Toulouse, France.,Neurology Department, CHU Toulouse Purpan, Toulouse, France
| | - Patrice Péran
- Toulouse NeuroImaging Center, Université de Toulouse, Inserm, Toulouse, France
| | - Emmanuel J Barbeau
- Brain and Cognition Research Centre, CNRS, University of Toulouse Paul Sabatier, Toulouse, France
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86
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Wang N, Xiao Z, Zhao Y, Wang B, Li X, Li J, Dai J. Collagen scaffold combined with human umbilical cord‐derived mesenchymal stem cells promote functional recovery after scar resection in rats with chronic spinal cord injury. J Tissue Eng Regen Med 2017; 12:e1154-e1163. [DOI: 10.1002/term.2450] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 01/17/2017] [Accepted: 05/04/2017] [Indexed: 12/21/2022]
Affiliation(s)
- Nuo Wang
- Key Laboratory of Molecular Developmental BiologyInstitute of Genetics and Developmental Biology, Chinese Academy of Sciences Beijing China
| | - Zhifeng Xiao
- Key Laboratory of Molecular Developmental BiologyInstitute of Genetics and Developmental Biology, Chinese Academy of Sciences Beijing China
| | - Yannan Zhao
- Key Laboratory of Molecular Developmental BiologyInstitute of Genetics and Developmental Biology, Chinese Academy of Sciences Beijing China
| | - Bin Wang
- Key Laboratory of Molecular Developmental BiologyInstitute of Genetics and Developmental Biology, Chinese Academy of Sciences Beijing China
| | - Xing Li
- Key Laboratory of Molecular Developmental BiologyInstitute of Genetics and Developmental Biology, Chinese Academy of Sciences Beijing China
| | - Jing Li
- Key Laboratory of Molecular Developmental BiologyInstitute of Genetics and Developmental Biology, Chinese Academy of Sciences Beijing China
| | - Jianwu Dai
- Key Laboratory of Molecular Developmental BiologyInstitute of Genetics and Developmental Biology, Chinese Academy of Sciences Beijing China
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Changes in White Matter Microstructure Impact Cognition by Disrupting the Ability of Neural Assemblies to Synchronize. J Neurosci 2017; 37:8227-8238. [PMID: 28743724 DOI: 10.1523/jneurosci.0560-17.2017] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 07/11/2017] [Accepted: 07/14/2017] [Indexed: 12/27/2022] Open
Abstract
Cognition is compromised by white matter (WM) injury but the neurophysiological alterations linking them remain unclear. We hypothesized that reduced neural synchronization caused by disruption of neural signal propagation is involved. To test this, we evaluated group differences in: diffusion tensor WM microstructure measures within the optic radiations, primary visual area (V1), and cuneus; neural phase synchrony to a visual attention cue during visual-motor task; and reaction time to a response cue during the same task between 26 pediatric patients (17/9: male/female) treated with cranial radiation treatment for a brain tumor (12.67 ± 2.76 years), and 26 healthy children (16/10: male/female; 12.01 ± 3.9 years). We corroborated our findings using a corticocortical computational model representing perturbed signal conduction from myelin. Patients show delayed reaction time, WM compromise, and reduced phase synchrony during visual attention compared with healthy children. Notably, using partial least-squares-path modeling we found that WM insult within the optic radiations, V1, and cuneus is a strong predictor of the slower reaction times via disruption of neural synchrony in visual cortex. Observed changes in synchronization were reproduced in a computational model of WM injury. These findings provide new evidence linking cognition with WM via the reliance of neural synchronization on propagation of neural signals.SIGNIFICANCE STATEMENT By comparing brain tumor patients to healthy children, we establish that changes in the microstructure of the optic radiations and neural synchrony during visual attention predict reaction time. Furthermore, by testing the directionality of these links through statistical modeling and verifying our findings with computational modeling, we infer a causal relationship, namely that changes in white matter microstructure impact cognition in part by disturbing the ability of neural assemblies to synchronize. Together, our human imaging data and computer simulations show a fundamental connection between WM microstructure and neural synchronization that is critical for cognitive processing.
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Hashemi M, Hutt A, Hight D, Sleigh J. Anesthetic action on the transmission delay between cortex and thalamus explains the beta-buzz observed under propofol anesthesia. PLoS One 2017; 12:e0179286. [PMID: 28622355 PMCID: PMC5473556 DOI: 10.1371/journal.pone.0179286] [Citation(s) in RCA: 14] [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: 05/27/2016] [Accepted: 05/26/2017] [Indexed: 11/18/2022] Open
Abstract
In recent years, more and more surgeries under general anesthesia have been performed with the assistance of electroencephalogram (EEG) monitors. An increase in anesthetic concentration leads to characteristic changes in the power spectra of the EEG. Although tracking the anesthetic-induced changes in EEG rhythms can be employed to estimate the depth of anesthesia, their precise underlying mechanisms are still unknown. A prominent feature in the EEG of some patients is the emergence of a strong power peak in the β-frequency band, which moves to the α-frequency band while increasing the anesthetic concentration. This feature is called the beta-buzz. In the present study, we use a thalamo-cortical neural population feedback model to reproduce observed characteristic features in frontal EEG power obtained experimentally during propofol general anesthesia, such as this beta-buzz. First, we find that the spectral power peak in the α- and δ-frequency ranges depend on the decay rate constant of excitatory and inhibitory synapses, but the anesthetic action on synapses does not explain the beta-buzz. Moreover, considering the action of propofol on the transmission delay between cortex and thalamus, the model reveals that the beta-buzz may result from a prolongation of the transmission delay by increasing propofol concentration. A corresponding relationship between transmission delay and anesthetic blood concentration is derived. Finally, an analytical stability study demonstrates that increasing propofol concentration moves the systems resting state towards its stability threshold.
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Affiliation(s)
- Meysam Hashemi
- INRIA Grand Est - Nancy, Team NEUROSYS, Villers-lès-Nancy, France
- CNRS, Loria, UMR nō 7503, Vandoeuvre-lès-Nancy, France
- Université de Lorraine, Loria, UMR nō 7503, Vandoeuvre-lès-Nancy, France
- Aix Marseille Université, INSERM, INS, Institut de Neurosciences des Systèmes, Marseille, France
| | - Axel Hutt
- German Meteorology Service, Offenbach am Main, Germany
- Department of Mathematics and Statistics, University of Reading, Reading, United Kingdom
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89
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Age-related changes of white matter association tracts in normal children throughout adulthood: a diffusion tensor tractography study. Neuroradiology 2017; 59:715-724. [PMID: 28580531 DOI: 10.1007/s00234-017-1858-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 05/22/2017] [Indexed: 12/22/2022]
Abstract
PURPOSE The aim of this study is to study the age, gender and lateral asymmetry-related white matter changes of long association tracts throughout late childhood and adolescence into adulthood using diffusion tensor tractography (DTT). METHODS DTT was performed in 44 healthy subjects aged 7-45 years. Fractional anisotropy (FA), radial diffusivity (RD), axial diffusivity (AD), Trace, density and volume were calculated for long association tracts, namely the inferior fronto-occipital fasciculus (IFOF), inferior longitudinal fasciculus (ILF), uncinate fasciculus, superior longitudinal fasciculus (SLF) and its arcuate fibres. FA and diffusivity indices were correlated as function of age using Pearson correlation test. Comparison between males and females, and comparison between both hemispheres among all participants were also performed. A p value less than .01 was considered significant. RESULTS The majority of the examined tracts (SLF and IFOF of both hemispheres, and the arcuate fasciculus, uncinate fasciculus, and ILF of the left hemisphere) followed a common pattern of metric changes with age. This pattern was characterized by significant FA increase accompanied by reduction in RD, Trace without significant AD changes. The right arcuate fasciculus showed similar pattern but without significant FA changes. The right uncinate and right ILF fasciculus demonstrated significant reduction in RD, Trace and AD, with and without significant FA increase, respectively. Left hemispheric dominance regarding the FA and diffusivity indices was demonstrated in uncinate fasciculus with no significant gender-related differences. CONCLUSION Significant microstructural tract-specific maturation processes continue throughout late childhood into adulthood. These processes may represent stages in a cascade of age-related maturation in white matter microstructure.
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90
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Kirkcaldie MTK, Dwyer ST. The third wave: Intermediate filaments in the maturing nervous system. Mol Cell Neurosci 2017; 84:68-76. [PMID: 28554564 DOI: 10.1016/j.mcn.2017.05.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 05/10/2017] [Accepted: 05/25/2017] [Indexed: 01/16/2023] Open
Abstract
Intermediate filaments are critical for the extreme structural specialisations of neurons, providing integrity in dynamic environments and efficient communication along axons a metre or more in length. As neurons mature, an initial expression of nestin and vimentin gives way to the neurofilament triplet proteins and α-internexin, substituted by peripherin in axons outside the CNS, which physically consolidate axons as they elongate and find their targets. Once connection is established, these proteins are transported, assembled, stabilised and modified, structurally transforming axons and dendrites as they acquire their full function. The interaction between these neurons and myelinating glial cells optimises the structure of axons for peak functional efficiency, a property retained across their lifespan. This finely calibrated structural regulation allows the nervous system to maintain timing precision and efficient control across large distances throughout somatic growth and, in maturity, as a plasticity mechanism allowing functional adaptation.
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Affiliation(s)
- Matthew T K Kirkcaldie
- School of Medicine, Wicking Dementia Research and Education Centre, Faculty of Health, University of Tasmania, Australia.
| | - Samuel T Dwyer
- School of Medicine, Wicking Dementia Research and Education Centre, Faculty of Health, University of Tasmania, Australia
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91
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Vyshedskiy A, Dunn R, Piryatinsky I. Neurobiological mechanisms for nonverbal IQ tests: implications for instruction of nonverbal children with autism. RESEARCH IDEAS AND OUTCOMES 2017. [DOI: 10.3897/rio.3.e13239] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Traditionally, the neurological correlates of IQ test questions are characterized qualitatively in terms of ‘control of attention’ and ‘working memory.’ In this report we attempt to characterize each IQ test question quantitatively by two factors: a) the number of disparate objects that have to be imagined in concert in order to solve the problem and, b) the amount of recruited posterior cortex territory. With such a classification, an IQ test can be understood on a neuronal level and a subject’s IQ score could be interpreted in terms of specific neurological mechanisms available to the subject.
Here we present the results of an analysis of the three most popular nonverbal IQ tests: Test of Nonverbal Intelligence (TONI-4), Standard Raven's Progressive Matrices, and Wechsler Intelligence Scale for Children (WISC-V). Our analysis shows that approximately half of all questions (52±0.02%) are limited to mental computations involving only a single object; these easier questions are found towards the beginning of each test. More difficult questions located towards the end of each test rely on mental synthesis of several disparate objects and the number of objects involved in computations gradually increases with question difficulty. These more challenging questions require the organization of wider posterior cortex networks by the lateral prefrontal cortex (PFC). This conclusion is in line with neuroimaging studies showing that activation level of the lateral PFC and the posterior cortex positively correlates with task difficulty. This analysis has direct implications for brain pathophysiology and, specifically, for therapeutic interventions for children with language impairment, most notably for children with Autism Spectrum Disorder (ASD) and other developmental disorders.
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92
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Klingseisen A, Lyons DA. Axonal Regulation of Central Nervous System Myelination: Structure and Function. Neuroscientist 2017; 24:7-21. [PMID: 28397586 DOI: 10.1177/1073858417703030] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Approximately half of the human brain consists of myelinated axons. Central nervous system (CNS) myelin is made by oligodendrocytes and is essential for nervous system formation, health, and function. Once thought simply as a static insulator that facilitated rapid impulse conduction, myelin is now known to be made and remodeled in to adult life. Oligodendrocytes have a remarkable capacity to differentiate by default, but many aspects of their development can be influenced by axons. However, how axons and oligodendrocytes interact and cooperate to regulate myelination in the CNS remains unclear. Here, we review recent advances in our understanding of how such interactions generate the complexity of myelination known to exist in vivo. We highlight intriguing results that indicate that the cross-sectional size of an axon alone may regulate myelination to a surprising degree. We also review new studies, which have highlighted diversity in the myelination of axons of different neuronal subtypes and circuits, and structure-function relationships, which suggest that myelinated axons can be exquisitely fine-tuned to mediate precise conduction needs. We also discuss recent advances in our understanding of how neuronal activity regulates CNS myelination, and aim to provide an integrated overview of how axon-oligodendrocyte interactions sculpt neuronal circuit structure and function.
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Affiliation(s)
- Anna Klingseisen
- 1 Centre for Neuroregeneration, University of Edinburgh, Edinburgh, UK
| | - David A Lyons
- 1 Centre for Neuroregeneration, University of Edinburgh, Edinburgh, UK
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93
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Arancibia-Cárcamo IL, Ford MC, Cossell L, Ishida K, Tohyama K, Attwell D. Node of Ranvier length as a potential regulator of myelinated axon conduction speed. eLife 2017; 6. [PMID: 28130923 PMCID: PMC5313058 DOI: 10.7554/elife.23329] [Citation(s) in RCA: 170] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 01/24/2017] [Indexed: 12/30/2022] Open
Abstract
Myelination speeds conduction of the nerve impulse, enhancing cognitive power. Changes of white matter structure contribute to learning, and are often assumed to reflect an altered number of myelin wraps. We now show that, in rat optic nerve and cerebral cortical axons, the node of Ranvier length varies over a 4.4-fold and 8.7-fold range respectively and that variation of the node length is much less along axons than between axons. Modelling predicts that these node length differences will alter conduction speed by ~20%, similar to the changes produced by altering the number of myelin wraps or the internode length. For a given change of conduction speed, the membrane area change needed at the node is >270-fold less than that needed in the myelin sheath. Thus, axon-specific adjustment of node of Ranvier length is potentially an energy-efficient and rapid mechanism for tuning the arrival time of information in the CNS. DOI:http://dx.doi.org/10.7554/eLife.23329.001 Information is transmitted around the nervous system as electrical signals passing along nerve cells. A fatty substance called myelin, which is wrapped around the nerve cells, increases the speed with which the signals travel along the nerve cells. This allows us to think and move faster than we would otherwise be able to do. The electrical signals start at small “nodes” between areas of myelin wrapping. Originally it was thought that we learn things mainly as a result of changes in the strength of connections between nerve cells, but recently it has been proposed that changes in myelin wrapping could also contribute to learning. Arancibia-Cárcamo, Ford, Cossell et al. investigated how much node structure varies in rat nerve cells, and whether differences in the length of nodes can fine-tune the activity of the nervous system. The experiments show that rat nerve cells do indeed have nodes with a range of different lengths. Calculations show that this could result in electrical signals moving at different speeds through different nerve cells. These findings raise the possibility that nerve cells actively alter the length of their nodes in order to alter their signal speed. The next step is to try to show experimentally that this happens during learning in animals. DOI:http://dx.doi.org/10.7554/eLife.23329.002
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Affiliation(s)
- I Lorena Arancibia-Cárcamo
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Marc C Ford
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Lee Cossell
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Kinji Ishida
- The Center for Electron Microscopy and Bio-Imaging Research, Iwate Medical University, Morioka, Japan
| | - Koujiro Tohyama
- The Center for Electron Microscopy and Bio-Imaging Research, Iwate Medical University, Morioka, Japan.,Department of Physiology, School of Dentistry, Iwate Medical University, Morioka, Japan
| | - David Attwell
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
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94
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Stedehouder J, Kushner SA. Myelination of parvalbumin interneurons: a parsimonious locus of pathophysiological convergence in schizophrenia. Mol Psychiatry 2017; 22:4-12. [PMID: 27646261 PMCID: PMC5414080 DOI: 10.1038/mp.2016.147] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2015] [Revised: 07/09/2016] [Accepted: 07/13/2016] [Indexed: 12/11/2022]
Abstract
Schizophrenia is a debilitating psychiatric disorder characterized by positive, negative and cognitive symptoms. Despite more than a century of research, the neurobiological mechanism underlying schizophrenia remains elusive. White matter abnormalities and interneuron dysfunction are the most widely replicated cellular neuropathological alterations in patients with schizophrenia. However, a unifying model incorporating these findings has not yet been established. Here, we propose that myelination of fast-spiking parvalbumin (PV) interneurons could be an important locus of pathophysiological convergence in schizophrenia. Myelination of interneurons has been demonstrated across a wide diversity of brain regions and appears highly specific for the PV interneuron subclass. Given the critical influence of fast-spiking PV interneurons for mediating oscillations in the gamma frequency range (~30-120 Hz), PV myelination is well positioned to optimize action potential fidelity and metabolic homeostasis. We discuss this hypothesis with consideration of data from human postmortem studies, in vivo brain imaging and electrophysiology, and molecular genetics, as well as fundamental and translational studies in rodent models. Together, the parvalbumin interneuron myelination hypothesis provides a falsifiable model for guiding future studies of schizophrenia pathophysiology.
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Affiliation(s)
- J Stedehouder
- Department of Psychiatry, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - S A Kushner
- Department of Psychiatry, Erasmus University Medical Center, Rotterdam, The Netherlands
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95
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Dubois J, Adibpour P, Poupon C, Hertz-Pannier L, Dehaene-Lambertz G. MRI and M/EEG studies of the White Matter Development in Human Fetuses and Infants: Review and Opinion. Brain Plast 2016; 2:49-69. [PMID: 29765848 PMCID: PMC5928537 DOI: 10.3233/bpl-160031] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Already during the last trimester of gestation, functional responses are recorded in foetuses and preterm newborns, attesting an already complex cerebral architecture. Then throughout childhood, anatomical connections are further refined but at different rates and over asynchronous periods across functional networks. Concurrently, infants gradually achieve new psychomotor and cognitive skills. Only the recent use of non-invasive techniques such as magnetic resonance imaging (MRI) and magneto- and electroencephalography (M/EEG) has opened the possibility to understand the relationships between brain maturation and skills development in vivo. In this review, we describe how these techniques have been applied to study the white matter maturation. At the structural level, the early architecture and myelination of bundles have been assessed with diffusion and relaxometry MRI, recently integrated in multi-compartment models and multi-parametric approaches. Nevertheless, technical limitations prevent us to map major developmental mechanisms such as fibers growth and pruning, and the progressive maturation at the bundle scale in case of mixing trajectories. At the functional level, M/EEG have been used to record different visual, somatosensory and auditory evoked responses. Because the conduction velocity of neural impulses increases with the myelination of connections, major changes in the components latency are observed throughout development. But so far, only a few studies have related structural and functional markers of white matter myelination. Such multi-modal approaches will be a major challenge in future research, not only to understand normal development, but also to characterize early mechanisms of pathologies and the influence of fetal and perinatal interventions on later outcome.
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Affiliation(s)
- Jessica Dubois
- INSERM, UMR992; CEA, NeuroSpin Center; University Paris Saclay, Gif-sur-Yvette, France
| | - Parvaneh Adibpour
- INSERM, UMR992; CEA, NeuroSpin Center; University Paris Saclay, Gif-sur-Yvette, France
| | - Cyril Poupon
- CEA, NeuroSpin Center, UNIRS; University Paris Saclay, Gif-sur-Yvette, France
| | - Lucie Hertz-Pannier
- CEA, NeuroSpin Center, UNIACT; University Paris Saclay, Gif-sur-Yvette, France; INSERM, UMR1129; University Paris Descartes, Paris, France
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96
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Hamilton NB, Clarke LE, Arancibia-Carcamo IL, Kougioumtzidou E, Matthey M, Káradóttir R, Whiteley L, Bergersen LH, Richardson WD, Attwell D. Endogenous GABA controls oligodendrocyte lineage cell number, myelination, and CNS internode length. Glia 2016; 65:309-321. [PMID: 27796063 PMCID: PMC5214060 DOI: 10.1002/glia.23093] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 10/07/2016] [Accepted: 10/11/2016] [Indexed: 11/30/2022]
Abstract
Adjusting the thickness and internodal length of the myelin sheath is a mechanism for tuning the conduction velocity of axons to match computational needs. Interactions between oligodendrocyte precursor cells (OPCs) and developing axons regulate the formation of myelin around axons. We now show, using organotypic cerebral cortex slices from mice expressing eGFP in Sox10‐positive oligodendrocytes, that endogenously released GABA, acting on GABAA receptors, greatly reduces the number of oligodendrocyte lineage cells. The decrease in oligodendrocyte number correlates with a reduction in the amount of myelination but also an increase in internode length, a parameter previously thought to be set by the axon diameter or to be a property intrinsic to oligodendrocytes. Importantly, while TTX block of neuronal activity had no effect on oligodendrocyte lineage cell number when applied alone, it was able to completely abolish the effect of blocking GABAA receptors, suggesting that control of myelination by endogenous GABA may require a permissive factor to be released from axons. In contrast, block of AMPA/KA receptors had no effect on oligodendrocyte lineage cell number or myelination. These results imply that, during development, GABA can act as a local environmental cue to control myelination and thus influence the conduction velocity of action potentials within the CNS. GLIA 2017;65:309–321
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Affiliation(s)
- Nicola B Hamilton
- Department of Neuroscience, Pharmacology and Physiology, University College London, London, WC1E 6BT, United Kingdom
| | - Laura E Clarke
- Department of Neuroscience, Pharmacology and Physiology, University College London, London, WC1E 6BT, United Kingdom
| | - I Lorena Arancibia-Carcamo
- Department of Neuroscience, Pharmacology and Physiology, University College London, London, WC1E 6BT, United Kingdom
| | - Eleni Kougioumtzidou
- Department of Cell and Developmental Biology, Wolfson Institute for Biomedical Research, University College London, London, WC1E 6BT, United Kingdom
| | - Moritz Matthey
- Wellcome Trust-MRC Cambridge Stem Cell Institute, Cambridge, CB2 1QR, United Kingdom
| | - Ragnhildur Káradóttir
- Wellcome Trust-MRC Cambridge Stem Cell Institute, Cambridge, CB2 1QR, United Kingdom
| | - Louise Whiteley
- Department of Neuroscience, Pharmacology and Physiology, University College London, London, WC1E 6BT, United Kingdom
| | - Linda H Bergersen
- Department of Oral Biology, Brain and Muscle Energy Group, University of Oslo, Blindern, Oslo, N-0317, Norway.,Department of Anatomy, University of Oslo, Blindern, Oslo, N-0317, Norway
| | - William D Richardson
- Department of Cell and Developmental Biology, Wolfson Institute for Biomedical Research, University College London, London, WC1E 6BT, United Kingdom
| | - David Attwell
- Department of Neuroscience, Pharmacology and Physiology, University College London, London, WC1E 6BT, United Kingdom
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97
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Itami C, Kimura F. Concurrently induced plasticity due to convergence of distinct forms of spike timing-dependent plasticity in the developing barrel cortex. Eur J Neurosci 2016; 44:2984-2990. [PMID: 27726220 DOI: 10.1111/ejn.13431] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 10/04/2016] [Accepted: 10/06/2016] [Indexed: 01/17/2023]
Abstract
Spike timing-dependent plasticity (STDP) has been demonstrated in a variety of neural circuits. Recent studies reveal that it plays a fundamental role in the formation and remodeling of neuronal circuits. We show here an interaction of two distinct forms of STDP in the mouse barrel cortex causing concurrent, plastic changes, potentially a novel mechanism underlying network remodeling. We previously demonstrated that during the second postnatal week, when layer four (L4) cells are forming synapses onto L2/3 cells, L4-L2/3 synapses exhibit STDP with only long-term potentiation (t-LTP). We also showed that at the same developmental stage, thalamus-L2/3 synapses express functional cannabinoid type 1 receptor (CB1R) and exhibit CB1R-dependent STDP with only long-term depression (t-LTD). Thus, distinct forms of STDP with opposite directions (potentiation vs. depression) converge in the target layer of L2/3 during the second postnatal week. As the canonical target layer of the thalamus is L4 and thalamic cells activate both L4 and L2/3 cells, in principle, thalamic activity could induce t-LTP at L4-L2/3 and t-LTD at thalamus-L2/3 simultaneously. In this study, we tested this possibility. We found that when spike timing stimulation was applied to the thalamus and L2/3 cells, synapses between the thalamus and L2/3 were weakened, whereas synapses between L4 and L2/3 were potentiated; therefore, converging STDP caused the predicted concurrent plasticity. We propose that developmentally transient convergences of STDP may play a role in shaping neural networks by facilitating L4-L2/3 formation and weakening aberrant thalamic innervation to L2/3, both driven by thalamic activity.
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Affiliation(s)
- Chiaki Itami
- Department of Physiology, Faculty of Medicine, Saitama Medical University, Moroyama, Saitama, 350-0495, Japan
| | - Fumitaka Kimura
- Department of Molecular Neuroscience, Osaka University Graduate School of Medicine, Suita, 565-0871, Japan
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98
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Schellenberger Costa M, Weigenand A, Ngo HVV, Marshall L, Born J, Martinetz T, Claussen JC. A Thalamocortical Neural Mass Model of the EEG during NREM Sleep and Its Response to Auditory Stimulation. PLoS Comput Biol 2016; 12:e1005022. [PMID: 27584827 PMCID: PMC5008627 DOI: 10.1371/journal.pcbi.1005022] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 06/17/2016] [Indexed: 11/18/2022] Open
Abstract
Few models exist that accurately reproduce the complex rhythms of the thalamocortical system that are apparent in measured scalp EEG and at the same time, are suitable for large-scale simulations of brain activity. Here, we present a neural mass model of the thalamocortical system during natural non-REM sleep, which is able to generate fast sleep spindles (12–15 Hz), slow oscillations (<1 Hz) and K-complexes, as well as their distinct temporal relations, and response to auditory stimuli. We show that with the inclusion of detailed calcium currents, the thalamic neural mass model is able to generate different firing modes, and validate the model with EEG-data from a recent sleep study in humans, where closed-loop auditory stimulation was applied. The model output relates directly to the EEG, which makes it a useful basis to develop new stimulation protocols. Sleep plays a pivotal role for the consolidation of memory. While REM sleep had originally been the focus of research due to its similarity with wakefulness, more recent studies suggest that different sleep stages are responsible for the consolidation of different types of memory. To better understand the changes in neuronal dynamics between the different sleep stages, neural mass models are a valuable tool, as they relate directly to the large-scale dynamics measured by an EEG. Here, we present a model of the sleeping thalamocortical system. We first show that the isolated thalamic submodule is able to generate different oscillatory behavior found in vivo. Furthermore, the full thalamocortical model reproduces the EEG of sleep stages N2 and N3 and preserves the temporal relationship between cortical K-complexes/slow oscillations and thalamic sleep spindles. A comparison with event related potential data from a recent sleep study in humans demonstrates its possible application in predicting the outcome of external stimulation on EEG rhythms. Our study shows, that a neural mass model incorporating few key mechanisms is sufficient to reproduce the complex brain dynamics observed during sleep.
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Affiliation(s)
- Michael Schellenberger Costa
- Institute for Neuro- and Bioinformatics, University of Lübeck, Lübeck, Germany
- Institute for Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany
- * E-mail:
| | - Arne Weigenand
- Institute for Neuro- and Bioinformatics, University of Lübeck, Lübeck, Germany
- Graduate School for Computing in Medicine and Life Science, University of Lübeck, Lübeck, Germany
| | - Hong-Viet V. Ngo
- Institute for Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany
| | - Lisa Marshall
- Graduate School for Computing in Medicine and Life Science, University of Lübeck, Lübeck, Germany
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Lübeck, Lübeck, Germany
| | - Jan Born
- Institute for Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany
- Center for Integrative Neuroscience, University of Tübingen, Tübingen, Germany
| | - Thomas Martinetz
- Institute for Neuro- and Bioinformatics, University of Lübeck, Lübeck, Germany
- Graduate School for Computing in Medicine and Life Science, University of Lübeck, Lübeck, Germany
| | - Jens Christian Claussen
- Institute for Neuro- and Bioinformatics, University of Lübeck, Lübeck, Germany
- Computational Systems Biology, Jacobs University Bremen, Bremen, Germany
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99
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Murphy E, Benítez-Burraco A. Language deficits in schizophrenia and autism as related oscillatory connectomopathies: An evolutionary account. Neurosci Biobehav Rev 2016; 83:742-764. [PMID: 27475632 DOI: 10.1016/j.neubiorev.2016.07.029] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 06/23/2016] [Accepted: 07/25/2016] [Indexed: 01/28/2023]
Abstract
Schizophrenia (SZ) and autism spectrum disorders (ASD) are characterised by marked language deficits, but it is not clear how these arise from gene mutations associated with the disorders. Our goal is to narrow the gap between SZ and ASD and, ultimately, give support to the view that they represent abnormal (but related) ontogenetic itineraries for the human faculty of language. We will focus on the distinctive oscillatory profiles of the SZ and ASD brains, in turn using these insights to refine our understanding of how the brain implements linguistic computations by exploring a novel model of linguistic feature-set composition. We will argue that brain rhythms constitute the best route to interpreting language deficits in both conditions and mapping them to neural dysfunction and risk alleles of the genes. Importantly, candidate genes for SZ and ASD are overrepresented among the gene sets believed to be important for language evolution. This translational effort may help develop an understanding of the aetiology of SZ and ASD and their high prevalence among modern populations.
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Affiliation(s)
- Elliot Murphy
- Division of Psychology and Language Sciences, University College London, London, United Kingdom.
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100
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Adolescence is associated with genomically patterned consolidation of the hubs of the human brain connectome. Proc Natl Acad Sci U S A 2016; 113:9105-10. [PMID: 27457931 DOI: 10.1073/pnas.1601745113] [Citation(s) in RCA: 299] [Impact Index Per Article: 37.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
How does human brain structure mature during adolescence? We used MRI to measure cortical thickness and intracortical myelination in 297 population volunteers aged 14-24 y old. We found and replicated that association cortical areas were thicker and less myelinated than primary cortical areas at 14 y. However, association cortex had faster rates of shrinkage and myelination over the course of adolescence. Age-related increases in cortical myelination were maximized approximately at the internal layer of projection neurons. Adolescent cortical myelination and shrinkage were coupled and specifically associated with a dorsoventrally patterned gene expression profile enriched for synaptic, oligodendroglial- and schizophrenia-related genes. Topologically efficient and biologically expensive hubs of the brain anatomical network had greater rates of shrinkage/myelination and were associated with overexpression of the same transcriptional profile as cortical consolidation. We conclude that normative human brain maturation involves a genetically patterned process of consolidating anatomical network hubs. We argue that developmental variation of this consolidation process may be relevant both to normal cognitive and behavioral changes and the high incidence of schizophrenia during human brain adolescence.
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