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Schwarz A, Feldman M, Le V, Dawson J, Liu CY, Francisco GE, Wolf SL, Dixit A, Alexander J, Ali R, Brown BL, Feng W, DeMark L, Hochberg LR, Kautz SA, Majid A, O'Dell MW, Redgrave J, Turner DL, Kimberley TJ, Cramer SC. Association that Neuroimaging and Clinical Measures Have with Change in Arm Impairment in a Phase 3 Stroke Recovery Trial. Ann Neurol 2025; 97:709-719. [PMID: 39676623 DOI: 10.1002/ana.27156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2024] [Revised: 11/25/2024] [Accepted: 11/27/2024] [Indexed: 12/17/2024]
Abstract
OBJECTIVE Vagus nerve stimulation (VNS) paired with rehabilitation therapy improved motor status compared to rehabilitation alone in the phase III VNS-REHAB stroke trial, but treatment response was variable and not associated with any clinical measures acquired at baseline, such as age or side of paresis. We hypothesized that neuroimaging measures would be associated with treatment-related gains, examining performance of regional injury measures versus global brain health measures in parallel with clinical measures. METHODS Baseline magnetic resonance imaging (MRI) scans in the VNS-REHAB trial were used to derive regional injury measures (extent of injury to corticospinal tract, the primary regional measure; plus extent of injury to precentral gyrus and postcentral gyrus; lesion volume; and lesion topography) and global brain health measures (degree of white matter hyperintensities, the primary global brain measure; plus volumes of cerebrospinal fluid, cortical gray matter, white matter, each thalamus, and total brain). Eight clinical measures assessed at baseline were also evaluated (treatment group, age, race, gender, paretic side, pre-stroke dominant hand, time since stroke, and baseline Fugl-Meyer upper extremity score). Bivariate analyses compared each measure with the primary trial end point (change in Fugl-Meyer upper extremity score from baseline to end of 6 weeks of treatment) across all subjects, with secondary analyses examining trial groups separately. RESULTS MRIs were available from 80 patients (age = 59.8 ± 9.5 years, 29 women). Across all patients, less white matter hyperintensities (r = -0.25, p = 0.028) at baseline was associated with larger Fugl-Meyer score change. In the VNS group, less white matter hyperintensities (r = -0.37, p = 0.018) and larger ipsilesional thalamus volume (r = 0.33, p = 0.046) were each associated with larger Fugl-Meyer score change. Analysis of covariance (ANCOVA) analyses tested the interaction that each baseline measure had with treatment group and found that the model examining white matter hyperintensities had a significant interaction term, indicating 2.3 less change in Fugl-Meyer Upper Extremity (FM-UE) points in the VNS group relative to the control group for each point increase in modified Fazekas scale. INTERPRETATION Neuroimaging measures are associated with extent of gains on the primary endpoint of a phase III stroke recovery trial. Among the neuroimaging measures examined, a measure of global brain health (extent of white matter hyperintensities) was better at explaining the change in arm impairment as compared with measures of regional injury; this was true when examining all study subjects as well as only those in the VNS group and is consistent with the global mechanism of action that VNS has throughout the cerebrum. Future studies can evaluate additional measures that further predict response to VNS therapy. The current findings suggest that individual patient neuroimaging results may be useful for a personalized medicine approach to stroke recovery therapeutics. ANN NEUROL 2025;97:709-719.
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Affiliation(s)
- Anne Schwarz
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA
- Department of Neurology, California Rehabilitation Institute, Los Angeles, CA
| | - Marc Feldman
- Department of Neurology, California Rehabilitation Institute, Los Angeles, CA
| | - Vu Le
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA
| | - Jesse Dawson
- Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Charles Y Liu
- USC Neurorestoration Center and Department of Neurological Surgery, USC Keck School of Medicine, Los Angeles, CA
- Department of Neurological Surgery, Rancho Los Amigos National Rehabilitation Center, Downey, CA
| | - Gerard E Francisco
- Department of Physical Medicine and Rehabilitation, The University of Texas Health Science Center McGovern Medical School, Houston, TX
- Department of Physical Medicine and Rehabilitation, The Institute for Rehabilitation and Research (TIRR) Memorial Hermann Hospital, Houston, TX
| | - Steven L Wolf
- Department of Rehabilitation Medicine, Division of Physical Therapy, Emory University School of Medicine, Atlanta, GA
| | - Anand Dixit
- Stroke Service, The Newcastle Upon Tyne Hospitals National Health Service Foundation Trust, Newcastle, United Kingdom
| | - Jen Alexander
- Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Rushna Ali
- Department of Neurosurgery, Mayo Clinic, Rochester, MN
| | | | - Wuwei Feng
- Department of Neurology, Duke University School of Medicine, Durham, NC
| | - Louis DeMark
- Department of Physical Therapy, Brooks Rehabilitation, Jacksonville, FL
| | - Leigh R Hochberg
- Department of Neurology, Center for Neurotechnology and Neurorecovery, Massachusetts General Hospital, Harvard Medical School, Boston, MA
- School of Engineering and Carney Institute for Brain Science, Brown University, Providence, RI
- VA RR&D Center for Neurorestoration and Neurotechnology, VA Medical Center, Providence, RI
| | - Steven A Kautz
- Department of Rehabilitation, Ralph H Johnson VA Medical Center, Charleston, SC
- Department of Health Sciences and Research, Medical University of South Carolina, Charleston, SC
| | - Arshad Majid
- Sheffield Institute for Neurological Sciences (SITraN), University of Sheffield, Sheffield, United Kingdom
- Department of Neurological Sciences, Sheffield Teaching Hospitals National Health Service Foundation Trust, Sheffield, United Kingdom
| | - Michael W O'Dell
- Department of Rehabilitation Medicine, Weill Cornell Medicine, New York City, NY
| | - Jessica Redgrave
- Sheffield Institute for Neurological Sciences (SITraN), University of Sheffield, Sheffield, United Kingdom
- Department of Neurological Sciences, Sheffield Teaching Hospitals National Health Service Foundation Trust, Sheffield, United Kingdom
| | - Duncan L Turner
- School of Health, Sport and Bioscience, University of East London, London, United Kingdom
| | - Teresa J Kimberley
- Department of Physical Therapy, MGH Institute of Health Professions, Boston, MA
| | - Steven C Cramer
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA
- Department of Neurology, California Rehabilitation Institute, Los Angeles, CA
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Garduño BM, Hanni P, Hays C, Cogram P, Insel N, Xu X. How the forebrain transitions to adulthood: developmental plasticity markers in a long-lived rodent reveal region diversity and the uniqueness of adolescence. Front Neurosci 2024; 18:1365737. [PMID: 38456144 PMCID: PMC10917993 DOI: 10.3389/fnins.2024.1365737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 02/02/2024] [Indexed: 03/09/2024] Open
Abstract
Maturation of the forebrain involves transitions from higher to lower levels of synaptic plasticity. The timecourse of these changes likely differs between regions, with the stabilization of some networks scaffolding the development of others. To gain better insight into neuroplasticity changes associated with maturation to adulthood, we examined the distribution of two molecular markers for developmental plasticity. We conducted the examination on male and female degus (Octodon degus), a rodent species with a relatively long developmental timecourse that offers a promising model for studying both development and age-related neuropathology. Immunofluorescent staining was used to measure perineuronal nets (PNNs), an extracellular matrix structure that emerges during the closure of critical plasticity periods, as well as microglia, resident immune cells that play a crucial role in synapse remodeling during development. PNNs (putatively restricting plasticity) were found to be higher in non-juvenile (>3 month) degus, while levels of microglia (putatively mediating plasticity) decreased across ages more gradually, and with varying timecourses between regions. Degus also showed notable variation in PNN levels between cortical layers and hippocampal subdivisions that have not been previously reported in other species. These results offer a glimpse into neuroplasticity changes occurring during degu maturation and highlight adolescence as a unique phase of neuroplasticity, in which PNNs have been established but microglia remain relatively high.
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Affiliation(s)
- B. Maximiliano Garduño
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, Irvine, CA, United States
| | - Patrick Hanni
- Department of Psychology, University of Montana, Missoula, MT, United States
| | - Chelsea Hays
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, Irvine, CA, United States
| | - Patricia Cogram
- Department of Ecological Sciences, Faculty of Sciences, Institute of Ecology and Biodiversity, Universidad de Chile, Santiago, Chile
- The Center for Neural Circuit Mapping, University of California, Irvine, Irvine, CA, United States
| | - Nathan Insel
- Department of Psychology, University of Montana, Missoula, MT, United States
- Department of Psychology, Wilfrid Laurier University, Waterloo, ON, Canada
| | - Xiangmin Xu
- Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, Irvine, CA, United States
- The Center for Neural Circuit Mapping, University of California, Irvine, Irvine, CA, United States
- Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, Irvine, CA, United States
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Mantel T, Jochim A, Meindl T, Deppe J, Zimmer C, Li Y, Haslinger B. Thalamic structural connectivity profiles in blepharospam/Meige's syndrome. Neuroimage Clin 2022; 34:103013. [PMID: 35483134 PMCID: PMC9125780 DOI: 10.1016/j.nicl.2022.103013] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 04/18/2022] [Accepted: 04/19/2022] [Indexed: 11/29/2022]
Abstract
BACKGROUND Blepharospasm is a debilitating focal dystonia characterized by involuntary eyelid spasms that can be accompanied by oromandibular muscle involvement (Meige's syndrome). Frequently observed abnormality in functional neuroimaging hints at an important position of the thalamus, that relays involved cortico-basal ganglia-cortical and cortico-cerebello-cortical circuits, within the abnormal network in blepharospasm. OBJECTIVE To characterize abnormal cortico-thalamic structural/streamline connectivity (SC) patterns in the disease, as well as their potential co-occurrence with abnormal subcortico-thalamo-cortical projections using diffusion tractography. METHODS Diffusion imaging was obtained in 17 patients with blepharospasm (5 with mild lower facial involvement) and 17 healthy controls. Probabilistic tractography was used for quantification of SC between six cortical regions and thalamus, and voxel-level thalamic SC mapping as well as evaluation of the thalamic SC distributions' topography by center-of-gravity analysis was performed. Post-hoc, correlations of SC with clinical parameters were evaluated. Further, white matter integrity was investigated within representative segments of the dentato-thalamo-cortical and pallido-thalamo-cortical tract. RESULTS Connectivity mapping showed significant reduction of right (pre)motor- and left occipital-thalamic SC, as well as a topographic shift of the left occipital-thalamic SC distribution in patients. Significant positive correlation of occipital-thalamic SC with disease severity was found. Post-hoc analysis revealed significantly reduced mean fractional anisotropy in patients within the dentato-thalamo-cortical trajectory connecting to right (pre)motor and left occipital cortex. CONCLUSION Abnormal occipital/motor SC provides evidence for dysfunction of the thalamus-relayed visual and motor network as a key aspect in the disease. Concurrent impairment of microstructural integrity within the dentato-thalamic trajectories targeting those cortices hints at cerebellar contribution.
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Affiliation(s)
- Tobias Mantel
- Department of Neurology, Klinikum rechts der Isar, Technische Universität München, Ismaninger Strasse 22, Munich, Germany
| | - Angela Jochim
- Department of Neurology, Klinikum rechts der Isar, Technische Universität München, Ismaninger Strasse 22, Munich, Germany
| | - Tobias Meindl
- Department of Neurology, Klinikum rechts der Isar, Technische Universität München, Ismaninger Strasse 22, Munich, Germany
| | - Jonas Deppe
- Department of Neurology, Klinikum rechts der Isar, Technische Universität München, Ismaninger Strasse 22, Munich, Germany
| | - Claus Zimmer
- Department of Neuroradiology, Klinikum rechts der Isar, Technische Universität München, Ismaninger Strasse 22, Munich, Germany
| | - Yong Li
- Department of Neurology, Klinikum rechts der Isar, Technische Universität München, Ismaninger Strasse 22, Munich, Germany
| | - Bernhard Haslinger
- Department of Neurology, Klinikum rechts der Isar, Technische Universität München, Ismaninger Strasse 22, Munich, Germany.
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The role of afferent input in postamputation pain: a randomized, double-blind, placebo-controlled crossover study. Pain 2020; 160:1622-1633. [PMID: 30817438 DOI: 10.1097/j.pain.0000000000001536] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In this randomized, double-blind, placebo-controlled crossover study, we investigated whether a peripheral nerve block could temporarily eliminate phantom and stump pain after amputation. Amputees with constant postamputation pain were included and randomized to receive a nerve block with lidocaine 2% with adrenaline or saline in a crossover design. Spontaneous phantom and stump pain and evoked responses were assessed at baseline and at fixed time-points until 120 minutes after lidocaine or saline injection. The primary outcome was the difference in absolute change between worst pain intensity, either phantom or stump pain, at baseline and at 30 minutes after lidocaine or saline injection. Twelve amputees were randomized and 9 patients were included in the analysis. The absolute change in median worst pain intensity between lidocaine and saline injection was -2.0 (interquartile range, -4.0 to 0.0) (n = 9, P = 0.12). Nine of 9 patients reported at least some pain relief after lidocaine injection compared with only 2 of 9 patients after saline injection (P = 0.02). Phantom pain intensity was significantly reduced after lidocaine compared with saline injection (P = 0.04), whereas there was no significant change in stump pain intensity between the 2 interventions (P = 0.17). In all 9 amputees, evoked responses were eliminated after lidocaine injection. Thus, our findings suggest that afferent input from the peripheral nervous system plays an important role in postamputation pain.
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Pei YC, Cheng YP, Chen JL, Lin CH, Wen CJ, Huang JJ. Early recovery of neuronal functioning in the sensory cortex after nerve reconstruction surgery. Restor Neurol Neurosci 2019; 37:409-419. [PMID: 31322584 PMCID: PMC6700653 DOI: 10.3233/rnn-190914] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND Nerve reconstructive surgery induces a transient loss and a prolonged and a gradual return of sensory inputs to the brain. It is unknown whether, following this massive peripheral denervation, the brain will experience a prolonged period of severe, intrinsic dysfunction. OBJECTIVE We aim to investigate the mechanisms of return of processing function in cortical neurons. METHODS We used the whisker model in rats to evaluate the functional recovery in the somatosensory cortex after a nerve reconstruction surgery. Multi-unit recording in the barrel cortex was performed in lightly anesthetized rats while their whiskers were stimulated by a whisker stimulator. RESULTS We observed a loss of neuronal responses to whisker stimulation 1 week after surgery, which started to recover 2 weeks after surgery. Following the surgery, only 11.8% of units had principle whiskers (PWs) returned to their original status while 17.7% had PWs different from their original status, indicating the effect of aberrant reinnervation on the whisker response map. CONCLUSIONS Robust neuronal responses to sensory stimulation even when only sparse sensory inputs are available in the early recovery phase. During this phase, aberrant reinnervation induces disorganized whisker tuning, a finding that might be account for the hypoesthesia and paresthesia during early recovery after nerve reconstruction.
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Affiliation(s)
- Yu-Chen Pei
- Department of Physical Medicine and Rehabilitation, Chang Gung Memorial Hospital at Linkou, Taoyuan City, Taiwan.,School of Medicine, Chang Gung University, Taoyuan City, Taiwan.,Center for Vascularized Composite Allotransplantation, Chang Gung Memorial Hospital, Taoyuan City, Taiwan.,Healthy Aging Research Center, Chang Gung University, Taoyuan City, Taiwan
| | - Yu-Po Cheng
- Department of Psychology, National Taiwan University, Taipei, Taiwan
| | - Ji-Lin Chen
- Department of Physical Medicine and Rehabilitation, Chang Gung Memorial Hospital at Linkou, Taoyuan City, Taiwan.,School of Medicine, Chang Gung University, Taoyuan City, Taiwan
| | - Cheng-Hung Lin
- School of Medicine, Chang Gung University, Taoyuan City, Taiwan.,Center for Vascularized Composite Allotransplantation, Chang Gung Memorial Hospital, Taoyuan City, Taiwan.,Department of Plastic and Reconstructive Surgery, Chang Gung Memorial Hospital at Linkou, Taoyuan City, Taiwan
| | - Chih-Jen Wen
- Center for Vascularized Composite Allotransplantation, Chang Gung Memorial Hospital, Taoyuan City, Taiwan.,Department of Plastic and Reconstructive Surgery, Chang Gung Memorial Hospital at Linkou, Taoyuan City, Taiwan
| | - Jian-Jia Huang
- Department of Physical Medicine and Rehabilitation, Chang Gung Memorial Hospital at Linkou, Taoyuan City, Taiwan.,School of Medicine, Chang Gung University, Taoyuan City, Taiwan.,Center for Vascularized Composite Allotransplantation, Chang Gung Memorial Hospital, Taoyuan City, Taiwan
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Does Size Really Matter? The Role of Tonotopic Map Area Dynamics for Sound Learning in Mouse Auditory Cortex. eNeuro 2017; 4:eN-COM-0002-17. [PMID: 28197554 PMCID: PMC5307296 DOI: 10.1523/eneuro.0002-17.2017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 01/03/2017] [Accepted: 01/04/2017] [Indexed: 11/21/2022] Open
Abstract
This commentary centers on the novel findings by Shepard et al. (2016) published in eNeuro. The authors interrogated tonotopic map dynamics in auditory cortex (ACtx) by employing a natural sound-learning paradigm, where mothers learn the importance of pup ultrasonic vocalizations (USVs), allowing Shepard et al. to probe the role of map area expansion for auditory learning. They demonstrate that auditory learning in this paradigm does not rely on map expansion but is facilitated by increased inhibition of neurons tuned to low-frequency sounds. Here, we discuss the findings in light of the emerging enthusiasm for cortical inhibitory interneurons for circuit function and hypothesize how a particular interneuron type might be causally involved for the intriguing results obtained by Shepard et al.
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Grossberg S, Kazerounian S. Phoneme restoration and empirical coverage of Interactive Activation and Adaptive Resonance models of human speech processing. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2016; 140:1130. [PMID: 27586743 DOI: 10.1121/1.4946760] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Magnuson [J. Acoust. Soc. Am. 137, 1481-1492 (2015)] makes claims for Interactive Activation (IA) models and against Adaptive Resonance Theory (ART) models of speech perception. Magnuson also presents simulations that claim to show that the TRACE model can simulate phonemic restoration, which was an explanatory target of the cARTWORD ART model. The theoretical analysis and review herein show that these claims are incorrect. More generally, the TRACE and cARTWORD models illustrate two diametrically opposed types of neural models of speech and language. The TRACE model embodies core assumptions with no analog in known brain processes. The cARTWORD model defines a hierarchy of cortical processing regions whose networks embody cells in laminar cortical circuits as part of the paradigm of laminar computing. cARTWORD further develops ART speech and language models that were introduced in the 1970s. It builds upon Item-Order-Rank working memories, which activate learned list chunks that unitize sequences to represent phonemes, syllables, and words. Psychophysical and neurophysiological data support Item-Order-Rank mechanisms and contradict TRACE representations of time, temporal order, silence, and top-down processing that exhibit many anomalous properties, including hallucinations of non-occurring future phonemes. Computer simulations of the TRACE model are presented that demonstrate these failures.
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Affiliation(s)
- Stephen Grossberg
- Departments of Mathematics, Psychology, and Biomedical Engineering, Center for Adaptive Systems, Graduate Program in Cognitive and Neural Systems, Center for Computational Neuroscience and Neural Technology, Boston University, Boston, Massachusetts 02215, USA
| | - Sohrob Kazerounian
- Nuance Communications, Inc., 1 Wayside Road, Burlington, Massachusetts 01803, USA
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Grossberg S. How Does the Cerebral Cortex Work? Development, Learning, Attention, and 3-D Vision by Laminar Circuits of Visual Cortex. ACTA ACUST UNITED AC 2016; 2:47-76. [PMID: 17715598 DOI: 10.1177/1534582303002001003] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
A key goal of behavioral and cognitive neuroscience is to link brain mechanisms to behavioral functions. The present article describes recent progress toward explaining how the visual cortex sees. Visual cortex, like many parts of perceptual and cognitive neocortex, is organized into six main layers of cells, as well as characteristic sublamina. Here it is proposed how these layered circuits help to realize processes of development, learning, perceptual grouping, attention, and 3-D vision through a combination of bottom-up, horizontal, and top-down interactions. A main theme is that the mechanisms which enable development and learning to occur in a stable way imply properties of adult behavior. These results thus begin to unify three fields: infant cortical development, adult cortical neurophysiology and anatomy, and adult visual perception. The identified cortical mechanisms promise to generalize to explain how other perceptual and cognitive processes work.
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Song W, Semework M. Tactile representation in somatosensory thalamus (VPL) and cortex (S1) of awake primate and the plasticity induced by VPL neuroprosthetic stimulation. Brain Res 2015; 1625:301-13. [PMID: 26348987 DOI: 10.1016/j.brainres.2015.08.046] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Revised: 08/20/2015] [Accepted: 08/31/2015] [Indexed: 11/19/2022]
Abstract
To further understand how tactile information is carried in somatosensory cortex (S1) and the thalamus (VPL), and how neuronal plasticity after neuroprosthetic stimulation affects sensory encoding, we chronically implanted microelectrode arrays across hand areas in both S1 and VPL, where neuronal activities were simultaneously recorded during tactile stimulation on the finger pad of awake monkeys. Tactile information encoded in the firing rate of individual units (rate coding) or in the synchrony of unit pairs (synchrony coding) was quantitatively assessed within the information theoretic-framework. We found that tactile information encoded in VPL was higher than that encoded in S1 for both rate coding and synchrony coding; rate coding carried greater information than synchrony coding for the same recording area. With the aim for neuroprosthetic stimulation, plasticity of the circuit was tested after 30 min of VPL electrical stimulation, where stimuli were delivered either randomly or contingent on the spiking of an S1 unit. We showed that neural encoding in VPL was more stable than in S1, which depends not only on the thalamic input but also on recurrent feedback. The percent change of mutual-information after stimulation was increased with closed-loop stimulation, but decreased with random stimulation. The underlying mechanisms during closed-loop stimulation might be spike-timing-dependent plasticity, while frequency-dependent synaptic plasticity might play a role in random stimulation. Our results suggest that VPL could be a promising target region for somatosensory stimulation with closed-loop brain-machine-interface applications.
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Affiliation(s)
- Weiguo Song
- Department of Physiology and Pharmacology, SUNY Downstate Medical Center, NY 11203, USA.
| | - Mulugeta Semework
- Joint Graduate Program in Biomedical Engineering SUNY Downstate and NYU-POLY, NY 11203, USA
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Bannister LC, Crewther SG, Gavrilescu M, Carey LM. Improvement in Touch Sensation after Stroke is Associated with Resting Functional Connectivity Changes. Front Neurol 2015; 6:165. [PMID: 26284024 PMCID: PMC4521505 DOI: 10.3389/fneur.2015.00165] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 07/07/2015] [Indexed: 12/24/2022] Open
Abstract
Background Distributed brain networks are known to be involved in facilitating behavioral improvement after stroke, yet few, if any, studies have investigated the relationship between improved touch sensation after stroke and changes in functional brain connectivity. Objective We aimed to identify how recovery of somatosensory function in the first 6 months after stroke was associated with functional network changes as measured using resting-state connectivity analysis of functional magnetic resonance imaging (fMRI) data. Methods Ten stroke survivors underwent clinical testing and resting-state fMRI scans at 1 and 6 months post-stroke. Ten age-matched healthy participants were included as controls. Results Patients demonstrated a wide range of severity of touch impairment 1 month post-stroke, followed by variable improvement over time. In the stroke group, significantly stronger interhemispheric functional correlations between regions of the somatosensory system, and with visual and frontal areas, were found at 6 months than at 1 month post-stroke. Clinical improvement in touch discrimination was associated with stronger correlations at 6 months between contralesional secondary somatosensory cortex (SII) and inferior parietal cortex and middle temporal gyrus, and between contralesional thalamus and cerebellum. Conclusion The strength of connectivity between somatosensory regions and distributed brain networks, including vision and attention networks, may change over time in stroke survivors with impaired touch discrimination. Connectivity changes from contralesional SII and contralesional thalamus are associated with improved touch sensation at 6 months post-stroke. These functional connectivity changes could represent future targets for therapy.
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Affiliation(s)
- Louise C Bannister
- Neurorehabilitation and Recovery, Stroke Division, Florey Institute of Neuroscience and Mental Health , Melbourne, VIC , Australia ; School of Psychology and Public Health, College of Science, Health and Engineering, La Trobe University , Melbourne, VIC , Australia ; Occupational Therapy, School of Allied Health, College of Science, Health and Engineering, La Trobe University , Melbourne, VIC , Australia
| | - Sheila G Crewther
- School of Psychology and Public Health, College of Science, Health and Engineering, La Trobe University , Melbourne, VIC , Australia
| | - Maria Gavrilescu
- Neurorehabilitation and Recovery, Stroke Division, Florey Institute of Neuroscience and Mental Health , Melbourne, VIC , Australia ; Defence Science and Technology Organisation , Melbourne, VIC , Australia
| | - Leeanne M Carey
- Neurorehabilitation and Recovery, Stroke Division, Florey Institute of Neuroscience and Mental Health , Melbourne, VIC , Australia ; Occupational Therapy, School of Allied Health, College of Science, Health and Engineering, La Trobe University , Melbourne, VIC , Australia ; Florey Department of Neuroscience and Mental Health, The University of Melbourne , Melbourne, VIC , Australia
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Niesters M, Sitsen E, Oudejans L, Vuyk J, Aarts LPHJ, Rombouts SARB, de Rover M, Khalili-Mahani N, Dahan A. Effect of deafferentation from spinal anesthesia on pain sensitivity and resting-state functional brain connectivity in healthy male volunteers. Brain Connect 2015; 4:404-16. [PMID: 24901040 DOI: 10.1089/brain.2014.0247] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Patients may perceive paradoxical heat sensation during spinal anesthesia. This could be due to deafferentation-related functional changes at cortical, subcortical, or spinal levels. In the current study, the effect of spinal deafferentation on sensory (pain) sensitivity was studied and linked to whole-brain functional connectivity as assessed by resting-state functional magnetic resonance imaging (RS-fMRI) imaging. Deafferentation was induced by sham or spinal anesthesia (15 mg bupivacaine injected at L3-4) in 12 male volunteers. RS-fMRI brain connectivity was determined in relation to eight predefined and seven thalamic resting-state networks (RSNs) and measured before, and 1 and 2 h after spinal/sham injection. To measure the effect of deafferentation on pain sensitivity, responses to heat pain were measured at 15-min intervals on nondeafferented skin and correlated to RS-fMRI connectivity data. Spinal anesthesia altered functional brain connectivity within brain regions involved in the sensory discriminative (i.e., pain intensity related) and affective dimensions of pain perception in relation to somatosensory and thalamic RSNs. A significant enhancement of pain sensitivity on nondeafferented skin was observed after spinal anesthesia compared to sham (area-under-the-curve [mean (SEM)]: 190.4 [33.8] versus 13.7 [7.2]; p<0.001), which significantly correlated to functional connectivity changes observed within the thalamus in relation to the thalamo-prefrontal network, and in the anterior cingulate cortex and insula in relation to the thalamo-parietal network. Enhanced pain sensitivity from spinal deafferentation correlated with functional connectivity changes within brain regions involved in affective and sensory pain processing and areas involved in descending control of pain.
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Affiliation(s)
- Marieke Niesters
- 1 Department of Anesthesiology, Leiden University Medical Center , Leiden, The Netherlands
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Measuring individual morphological relationship of cortical regions. J Neurosci Methods 2014; 237:103-7. [PMID: 25220868 DOI: 10.1016/j.jneumeth.2014.09.003] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Revised: 08/12/2014] [Accepted: 09/05/2014] [Indexed: 12/11/2022]
Abstract
BACKGROUND Although local features of brain morphology have been widely investigated in neuroscience, the inter-regional relations in brain morphology have rarely been investigated, especially not for individual participants. NEW METHOD In this paper, we proposed a novel framework for investigating this relation based on an individual's magnetic resonance imaging (MRI) data. The key idea was to estimate the probability density function (PDF) of local morphological features within a brain region to provide a global description of this region. Then, the inter-regional relations were quantified by calculating the similarity of the PDFs for pairs of regions based on the Kullback-Leibler (KL) divergence. RESULTS For illustration, we applied this approach to a pre-post intervention study to investigate the longitudinal changes in morphological relations after long-term sleep deprivation. The results suggest the potential application of this new method for studies on individual differences in brain structure. COMPARISON WITH EXISTING METHODS The current method can be employed to estimate individual morphological relations between regions, which have been largely ignored by previous studies. CONCLUSIONS Our morphological relation metric, as a novel quantitative biomarker, can be used to investigate normal individual variability and even within-individual alterations/abnormalities in brain structure.
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Bohlken MM, Brouwer RM, Mandl RC, van Haren NE, Brans RG, van Baal GCM, de Geus EJ, Boomsma DI, Kahn RS, Hulshoff Pol HE. Genes contributing to subcortical volumes and intellectual ability implicate the thalamus. Hum Brain Mapp 2014; 35:2632-42. [PMID: 24038793 PMCID: PMC6869799 DOI: 10.1002/hbm.22356] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Revised: 06/03/2013] [Accepted: 06/10/2013] [Indexed: 12/31/2022] Open
Abstract
It has been shown that brain volume and general intellectual ability are to a significant extent influenced by the same genetic factors. Several cortical regions of the brain also show a genetic correlation with intellectual ability, demonstrating that intellectual functioning is probably represented in a heritable distributed network of cortical regions throughout the brain. This study is the first to investigate a genetic association between subcortical volumes and intellectual ability, taking into account the thalamus, caudate nucleus, putamen, globus pallidus, hippocampus, amygdala, and nucleus accumbens using an extended twin design. Genetic modeling was performed on a healthy adult twin sample consisting of 106 twin pairs and 30 of their siblings, IQ data was obtained from 132 subjects. Our results demonstrate that of all subcortical volumes measured, only thalamus volume is significantly correlated with intellectual functioning. Importantly, the association found between thalamus volume and intellectual ability is significantly influenced by a common genetic factor. This genetic factor is also implicated in cerebral brain volume. The thalamus, with its widespread cortical connections, may thus play a key role in human intelligence.
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Affiliation(s)
| | | | | | | | | | | | | | | | - René S. Kahn
- Department of PsychiatryUMC UtrechtThe Netherlands
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Adaptive Resonance Theory: How a brain learns to consciously attend, learn, and recognize a changing world. Neural Netw 2013; 37:1-47. [PMID: 23149242 DOI: 10.1016/j.neunet.2012.09.017] [Citation(s) in RCA: 190] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2012] [Revised: 08/24/2012] [Accepted: 09/24/2012] [Indexed: 11/17/2022]
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Lim DH, Mohajerani MH, Ledue J, Boyd J, Chen S, Murphy TH. In vivo Large-Scale Cortical Mapping Using Channelrhodopsin-2 Stimulation in Transgenic Mice Reveals Asymmetric and Reciprocal Relationships between Cortical Areas. Front Neural Circuits 2012; 6:11. [PMID: 22435052 PMCID: PMC3304170 DOI: 10.3389/fncir.2012.00011] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Accepted: 02/24/2012] [Indexed: 12/27/2022] Open
Abstract
We have mapped intracortical activity in vivo independent of sensory input using arbitrary point channelrhodopsin-2 (ChR2) stimulation and regional voltage sensitive dye imaging in B6.Cg-Tg (Thy1-COP4/EYFP)18Gfng/J transgenic mice. Photostimulation of subsets of deep layer pyramidal neurons within forelimb, barrel, or visual primary sensory cortex led to downstream cortical maps that were dependent on synaptic transmission and were similar to peripheral sensory stimulation. ChR2-evoked maps confirmed homotopic connections between hemispheres and intracortical sensory and motor cortex connections. This ability of optogentically activated subpopulations of neurons to drive appropriate downstream maps suggests that mechanisms exist to allow prototypical cortical maps to self-assemble from the stimulation of neuronal subsets. Using this principle of map self-assembly, we employed ChR2 point stimulation to map connections between cortical areas that are not selectively activated by peripheral sensory stimulation or behavior. Representing the functional cortical regions as network nodes, we identified asymmetrical connection weights in individual nodes and identified the parietal association area as a network hub. Furthermore, we found that the strength of reciprocal intracortical connections between primary and secondary sensory areas are unequal, with connections from primary to secondary sensory areas being stronger than the reciprocal.
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Affiliation(s)
- Diana H Lim
- Department of Psychiatry, University of British Columbia Vancouver, BC, Canada
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Oeschger FM, Wang WZ, Lee S, García-Moreno F, Goffinet AM, Arbonés ML, Rakic S, Molnár Z. Gene expression analysis of the embryonic subplate. ACTA ACUST UNITED AC 2011; 22:1343-59. [PMID: 21862448 PMCID: PMC4972418 DOI: 10.1093/cercor/bhr197] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The subplate layer of the cerebral cortex is comprised of a heterogeneous population of cells and contains some of the earliest-generated neurons. In the embryonic brain, subplate cells contribute to the guidance and areal targeting of thalamocortical axons. At later developmental stages, they are predominantly involved in the maturation and plasticity of the cortical circuitry and the establishment of functional modules. We aimed to further characterize the embryonic murine subplate population by establishing a gene expression profile at embryonic day (E) 15.5 using laser capture microdissection and microarrays. The microarray identified over 300 transcripts with higher expression in the subplate compared with the cortical plate at this stage. Using quantitative reverse transcription-polymerase chain reaction, in situ hybridization (ISH), and immunohistochemistry (IHC), we have confirmed specific expression in the E15.5 subplate for 13 selected genes, which have not been previously associated with this compartment (Abca8a, Cdh10, Cdh18, Csmd3, Gabra5, Kcnt2, Ogfrl1, Pls3, Rcan2, Sv2b, Slc8a2, Unc5c, and Zdhhc2). In the reeler mutant, the expression of the majority of these genes (9 of 13) was shifted in accordance with the altered position of subplate. These genes belong to several functional groups and likely contribute to synapse formation and axonal growth and guidance in subplate cells.
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Affiliation(s)
- Franziska M Oeschger
- Department of Physiology, Anatomy and Genetics, Oxford University, Oxford OX1 3QX, UK
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Targeted mini-strokes produce changes in interhemispheric sensory signal processing that are indicative of disinhibition within minutes. Proc Natl Acad Sci U S A 2011; 108:E183-91. [PMID: 21576480 DOI: 10.1073/pnas.1101914108] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Most processing of sensation involves the cortical hemisphere opposite (contralateral) to the stimulated limb. Stroke patients can exhibit changes in the interhemispheric balance of sensory signal processing. It is unclear whether these changes are the result of poststroke rewiring and experience, or whether they could result from the immediate effect of circuit loss. We evaluated the effect of mini-strokes over short timescales (<2 h) where cortical rewiring is unlikely by monitoring sensory-evoked activity throughout much of both cortical hemispheres using voltage-sensitive dye imaging. Blockade of a single pial arteriole within the C57BL6J mouse forelimb somatosensory cortex reduced the response evoked by stimulation of the limb contralateral to the stroke. However, after stroke, the ipsilateral (uncrossed) forelimb response within the unaffected hemisphere was spared and became independent of the contralateral forelimb cortex. Within the unaffected hemisphere, mini-strokes in the opposite hemisphere significantly enhanced sensory responses produced by stimulation of either contralateral or ipsilateral pathways within 30-50 min of stroke onset. Stroke-induced enhancement of responses within the spared hemisphere was not reproduced by inhibition of either cortex or thalamus using pharmacological agents in nonischemic animals. I/LnJ acallosal mice showed similar rapid interhemispheric redistribution of sensory processing after stroke, suggesting that subcortical connections and not transcallosal projections were mediating the novel activation patterns. Thalamic inactivation before stroke prevented the bilateral rearrangement of sensory responses. These findings suggest that acute stroke, and not merely loss of activity, activates unique pathways that can rapidly redistribute function within the spared cortical hemisphere.
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Carey LM, Abbott DF, Harvey MR, Puce A, Seitz RJ, Donnan GA. Relationship between touch impairment and brain activation after lesions of subcortical and cortical somatosensory regions. Neurorehabil Neural Repair 2011; 25:443-57. [PMID: 21382887 DOI: 10.1177/1545968310395777] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
BACKGROUND The neural basis underlying somatosensory impairment and recovery poststroke is virtually unexplored. OBJECTIVE To investigate the relationship between touch discrimination impairment and task-related brain activation in stroke survivors with somatosensory impairment following subcortical or cortical lesions. METHODS A total of 19 stroke survivors with touch impairment were investigated using fMRI and a touch discrimination paradigm 1-month poststroke; 11 had subcortical and 8 cortical sensory lesions; 12 age-matched healthy controls were also studied. Mean task-related contrast images were regressed with sensory impairment using random effects analysis for each subgroup and the total group. RESULTS There was no significant difference in touch impairment between stroke subgroups. Touch discrimination of the affected hand correlated negatively with task-related activation in the ipsilesional primary somatosensory cortex (SI; adjacent to the SI hand area activated in healthy controls); ipsilesional secondary somatosensory cortex (SII); contralesional thalamus; and attention-related frontal and occipital regions in the subcortical group. In contrast, the cortical group did not show significant correlated activity. Yet there was no significant between-group difference in a priori somatosensory regions: only in the superior medial frontal gyrus. A negative correlation was observed in the contralesional thalamus for the total group, irrespective of lesion type. CONCLUSION The findings provide novel evidence of neural correlates of poststroke touch impairment involving a distributed network of ipsilesional SI and SII, the contralesional thalamus, and frontal attention regions, particularly following subcortical lesions. Further systematic investigation of a modulatory role for ipsilesional SI, the thalamus, and frontal attention regions in sensory processing and recovery is warranted, particularly given implications for rehabilitation.
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Affiliation(s)
- Leeanne M Carey
- National Stroke Research Institute, Florey Neuroscience Institutes, Melbourne, Victoria, Australia.
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Pawela CP, Biswal BB, Hudetz AG, Li R, Jones SR, Cho YR, Matloub HS, Hyde JS. Interhemispheric neuroplasticity following limb deafferentation detected by resting-state functional connectivity magnetic resonance imaging (fcMRI) and functional magnetic resonance imaging (fMRI). Neuroimage 2009; 49:2467-78. [PMID: 19796693 DOI: 10.1016/j.neuroimage.2009.09.054] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2008] [Revised: 08/28/2009] [Accepted: 09/22/2009] [Indexed: 12/31/2022] Open
Abstract
Functional connectivity magnetic resonance imaging (fcMRI) studies in rat brain show brain reorganization following peripheral nerve injury. Subacute neuroplasticity was observed 2 weeks following transection of the four major nerves of the brachial plexus. Direct stimulation of the intact radial nerve reveals a functional magnetic resonance imaging (fMRI) activation pattern in the forelimb regions of the sensory and motor cortices that is significantly different from that observed in normal rats. Results of this fMRI experiment were used to determine seed voxel regions for fcMRI analysis. Intrahemispheric connectivities in the sensorimotor forelimb representations in both hemispheres are largely unaffected by deafferentation, whereas substantial disruption of interhemispheric sensorimotor cortical connectivity occurs. In addition, significant intra- and interhemispheric changes in connectivities of thalamic nuclei were found. These are the central findings of the study. They could not have been obtained from fMRI studies alone-both fMRI and fcMRI are needed. The combination provides a general marker for brain plasticity. The rat visual system was studied in the same animals as a control. No neuroplastic changes in connectivities were found in the primary visual cortex upon forelimb deafferentation. Differences were noted in regions responsible for processing multisensory visual-motor information. This incidental discovery is considered to be significant. It may provide insight into phantom limb epiphenomena.
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Affiliation(s)
- Christopher P Pawela
- Department of Biophysics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
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20
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Navarro X. Chapter 27: Neural plasticity after nerve injury and regeneration. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2009; 87:483-505. [PMID: 19682656 DOI: 10.1016/s0074-7742(09)87027-x] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Injuries to the peripheral nerves result in partial or total loss of motor, sensory, and autonomic functions in the denervated segments of the body due to the interruption of axons, degeneration of distal nerve fibers, and eventual death of axotomized neurons. Functional deficits caused by nerve injuries can be compensated by reinnervation of denervated targets by regenerating injured axons or by collateral branching of undamaged axons, and remodeling of nervous system circuitry related to the lost functions. Plasticity of central connections may compensate functionally for the lack of adequate target reinnervation; however, plasticity has limited effects on disturbed sensory localization or fine motor control after injuries, and may even result in maladaptive changes, such as neuropathic pain and hyperreflexia. After axotomy, neurons shift from a transmitter to a regenerative phenotype, activating molecular pathways that promote neuronal survival and axonal regeneration. Peripheral nerve injuries also induce a cascade of events, at the molecular, cellular, and system levels, initiated by the injury and progressing throughout plastic changes at the spinal cord, brainstem nuclei, thalamus, and brain cortex. Mechanisms involved in these changes include neurochemical changes, functional alterations of excitatory and inhibitory synaptic connections, sprouting of new connections, and reorganization of sensory and motor central maps. An important direction for research is the development of therapeutic strategies that enhance axonal regeneration, promote selective target reinnervation, and are also able to modulate central nervous system reorganization, amplifying positive adaptive changes that improve functional recovery and also reducing undesirable effects.
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Affiliation(s)
- Xavier Navarro
- Institute of Neurosciences and Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain
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Grachev ID, Swarnkar A, Szeverenyi NM, Ramachandran TS, Apkarian AV. Aging alters the multichemical networking profile of the human brain: an in vivo1H-MRS study of young versus middle-aged subjects. J Neurochem 2008. [DOI: 10.1046/j.1471-4159.2001.00238.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Abstract
Limb amputation results in plasticity of connections between the brain and muscles; the cortical motor representation of the missing limb seemingly disappears. The disappearance of the hand's motor representation is, however, difficult to reconcile with evidence that a perceptual representation of the missing limb persists in the form of a phantom limb endowed with sensory and motor qualities. Here, we argue that despite considerable reorganization within the motor cortex of upper-limb amputees, the representation of the amputated hand does not disappear. We hypothesize that two levels of hand-movement representation coexist within the primary motor cortex; at one level, limb movements are specified in terms of arm and hand motor commands, and at another level, limb movements are specified as muscles synergies. We propose that primary motor cortex reorganization after amputation concerns primarily the upper limb's muscular map but not its motor command map and that the integrity of the motor command map underlies the existence of the phantom limb.
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Navarro X, Vivó M, Valero-Cabré A. Neural plasticity after peripheral nerve injury and regeneration. Prog Neurobiol 2007; 82:163-201. [PMID: 17643733 DOI: 10.1016/j.pneurobio.2007.06.005] [Citation(s) in RCA: 643] [Impact Index Per Article: 35.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2006] [Revised: 02/18/2007] [Accepted: 06/14/2007] [Indexed: 01/01/2023]
Abstract
Injuries to the peripheral nerves result in partial or total loss of motor, sensory and autonomic functions conveyed by the lesioned nerves to the denervated segments of the body, due to the interruption of axons continuity, degeneration of nerve fibers distal to the lesion and eventual death of axotomized neurons. Injuries to the peripheral nervous system may thus result in considerable disability. After axotomy, neuronal phenotype switches from a transmitter to a regenerative state, inducing the down- and up-regulation of numerous cellular components as well as the synthesis de novo of some molecules normally not expressed in adult neurons. These changes in gene expression activate and regulate the pathways responsible for neuronal survival and axonal regeneration. Functional deficits caused by nerve injuries can be compensated by three neural mechanisms: the reinnervation of denervated targets by regeneration of injured axons, the reinnervation by collateral branching of undamaged axons, and the remodeling of nervous system circuitry related to the lost functions. Plasticity of central connections may compensate functionally for the lack of specificity in target reinnervation; plasticity in human has, however, limited effects on disturbed sensory localization or fine motor control after injuries, and may even result in maladaptive changes, such as neuropathic pain, hyperreflexia and dystonia. Recent research has uncovered that peripheral nerve injuries induce a concurrent cascade of events, at the systemic, cellular and molecular levels, initiated by the nerve injury and progressing throughout plastic changes at the spinal cord, brainstem relay nuclei, thalamus and brain cortex. Mechanisms for these changes are ubiquitous in central substrates and include neurochemical changes, functional alterations of excitatory and inhibitory connections, atrophy and degeneration of normal substrates, sprouting of new connections, and reorganization of somatosensory and motor maps. An important direction for ongoing research is the development of therapeutic strategies that enhance axonal regeneration, promote selective target reinnervation, but are also able to modulate central nervous system reorganization, amplifying those positive adaptive changes that help to improve functional recovery but also diminishing undesirable consequences.
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Affiliation(s)
- X Navarro
- Group of Neuroplasticity and Regeneration, Institute of Neurosciences and Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain.
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Flor H, Birbaumer N. Phantom limb pain: cortical plasticity and novel therapeutic approaches. Curr Opin Anaesthesiol 2007; 13:561-4. [PMID: 17016358 DOI: 10.1097/00001503-200010000-00013] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Phantom limb pain is still a very frequent consequence of peripheral deafferentation or amputation of a limb. Recent findings from animal and neuroimaging studies suggest that phantom limb pain might be a central phenomenon, related to changes in the cortical, thalamic and spinal representation of the painful limb, and might be a type of somatosensory pain memory. Based on these assumptions, new treatment approaches focus on sensory discrimination training or motor cortex stimulation in an effort to influence cortical reorganization. Prevention of perpetuation of a somatosensory pain memory might also be possible through pharmacological agents such as N-methyl-D-aspartate antagonists and gamma-aminobutyric acid agonists, substances that have been shown to influence and prevent cortical reorganization.
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Affiliation(s)
- H Flor
- Department of Clinical and Cognitive Neuroscience, Central Institute of Mental Health, Mannheim, Germany.
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Grossberg S. Towards a unified theory of neocortex: laminar cortical circuits for vision and cognition. PROGRESS IN BRAIN RESEARCH 2007; 165:79-104. [DOI: 10.1016/s0079-6123(06)65006-1] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Flor H, Nikolajsen L, Staehelin Jensen T. Phantom limb pain: a case of maladaptive CNS plasticity? Nat Rev Neurosci 2006; 7:873-81. [PMID: 17053811 DOI: 10.1038/nrn1991] [Citation(s) in RCA: 573] [Impact Index Per Article: 30.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Phantom pain refers to pain in a body part that has been amputated or deafferented. It has often been viewed as a type of mental disorder or has been assumed to stem from pathological alterations in the region of the amputation stump. In the past decade, evidence has accumulated that phantom pain might be a phenomenon of the CNS that is related to plastic changes at several levels of the neuraxis and especially the cortex. Here, we discuss the evidence for putative pathophysiological mechanisms with an emphasis on central, and in particular cortical, changes. We cite both animal and human studies and derive suggestions for innovative interventions aimed at alleviating phantom pain.
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Affiliation(s)
- Herta Flor
- Department of Clinical and Cognitive Neuroscience, University of Heidelberg, Central Institute of Mental Health, D-68159 Mannheim, Germany.
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Grossberg S, Seidman D. Neural dynamics of autistic behaviors: cognitive, emotional, and timing substrates. Psychol Rev 2006; 113:483-525. [PMID: 16802879 DOI: 10.1037/0033-295x.113.3.483] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
What brain mechanisms underlie autism, and how do they give rise to autistic behavioral symptoms? This article describes a neural model, called the Imbalanced Spectrally Timed Adaptive Resonance Theory (iSTART) model, that proposes how cognitive, emotional, timing, and motor processes that involve brain regions such as the prefrontal and temporal cortex, amygdala, hippocampus, and cerebellum may interact to create and perpetuate autistic symptoms. These model processes were originally developed to explain data concerning how the brain controls normal behaviors. The iSTART model shows how autistic behavioral symptoms may arise from prescribed breakdowns in these brain processes, notably a combination of underaroused emotional depression in the amygdala and related affective brain regions, learning of hyperspecific recognition categories in the temporal and prefrontal cortices, and breakdowns of adaptively timed attentional and motor circuits in the hippocampal system and cerebellum. The model clarifies how malfunctions in a subset of these mechanisms can, through a systemwide vicious circle of environmentally mediated feedback, cause and maintain problems with them all.
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Affiliation(s)
- Stephen Grossberg
- Department of Cognitive and Neural Systems, Center for Adaptive Systems and Center of Excellence for Learning in Education, Science, and Technology, Boston University, 677 Beacon Street, Boston, MA 02215, USA.
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Khaslavskaia S, Klucharev V, Chen ACN, Sinkjaer T. The effect of repetitive electrical stimulation on the motor evoked hemodynamic responses. Int J Neurosci 2006; 116:331-49. [PMID: 16484059 DOI: 10.1080/00207450500436702] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The aim of this study was to investigate the influence of short-term repetitive electrical stimulation (rES training session) on the motor-evoked hemodynamic responses. The fMRI echo-planar images (EPI) were recorded before and after the rES training. The right median nerve (MN) was stimulated during rES. The rES training resulted in a significant increase in activity in a number of supraspinal regions, including sensorimotor and associative cortical areas. On the subcortical level, the effect was also found in the cerebellum, the midbrain, and the thalamus. Possible mechanisms of the neuronal plastic changes observed after rES, and memory processes involved in learning are discussed.
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Wang X, Wall JT. Cortical influences on sizes and rapid plasticity of tactile receptive fields in the dorsal column nuclei. J Comp Neurol 2005; 489:241-8. [PMID: 15984000 DOI: 10.1002/cne.20642] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The cerebral cortex influences subcortical processing. In the somatosensory system, descending cortical inputs contribute in specific ways to the sizes and plasticity of tactile receptive fields (RFs) in the thalamus, but less is known about cortical influences on these aspects of brainstem RFs. The present studies evaluated how loss of cortical inputs affects sizes and plasticity of RFs in the brainstem dorsal column nuclei (DCN) when peripheral inputs were normal and when peripheral inputs were acutely disrupted. Loss of cortical inputs was produced by acute lesion of somatosensory, motor, and adjacent cortex, whereas disruption of peripheral inputs was produced by cutaneous microinjection of lidocaine (LID). Modest or no changes in sizes of DCN RFs, comparable to changes during control periods of no treatment, were seen in response to cortical lesion. LID caused rapid enlargements in RFs when cortex was intact. LID also caused rapid RF enlargements after cortical lesion, and these enlargements were greater than post-LID enlargements when cortex was intact. These results indicate that normally sized RFs continue to be produced in the DCN after loss of cortical input. Cortex is also not required for RF enlargements after LID; however, cortical inputs have a constraining effect on these enlargements. Considered with findings from previous thalamic studies, these results suggest that cortical influences on RF size and plasticity in the DCN and thalamus differ in some respects.
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Affiliation(s)
- Xin Wang
- Department of Neurosciences, Medical College of Ohio, Toledo, Ohio 43614-5804, USA
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Chowdhury SA, Greek KA, Rasmusson DD. Changes in corticothalamic modulation of receptive fields during peripheral injury-induced reorganization. Proc Natl Acad Sci U S A 2004; 101:7135-40. [PMID: 15100406 PMCID: PMC406478 DOI: 10.1073/pnas.0307840101] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The influence of corticothalamic projections on the thalamus during different stages of reorganization was determined in anesthetized raccoons that had undergone previous removal of a single forepaw digit. Single-unit recordings were made from 522 sites in the somatosensory nucleus of the thalamus (ventroposterior lateral nucleus) before and after lesioning parts of primary somatosensory cortex. In those parts of ventroposterior lateral nucleus that had intact input from the periphery, the cortical lesion resulted in an immediate 85% increase in receptive field (RF) size. In animals studied 2-6 weeks after digit amputation, peripherally denervated thalamic neurons had unique RFs that were larger than normal, and these were not further enlarged by cortical lesion. However, at longer periods of reorganization (>4 mo), when the new RFs of denervated neurons had decreased in size, cortical lesion again produced expansion of RF size. These data demonstrate that corticothalamic fibers modulate the spatial extent of thalamic RFs in intact animals, probably by controlling intrathalamic inhibition. This corticothalamic modulation is ineffective during the early stages of injury-induced reorganization when new RFs are being formed, but is reinstated after the new RFs have become stabilized. The fact that neurons in the denervated thalamic region retained their unique RFs after cortical lesion indicates that their new inputs are not being relayed from a reorganized cortex and support the view that some plasticity occurs in or below the thalamus.
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Affiliation(s)
- S A Chowdhury
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada B3H 1X5
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Abstract
Peripheral denervation has been shown to cause reorganization of the deafferented somatotopic region in primary somatosensory cortex (S1). However, the basic mechanisms that underlie reorganization are not well understood. In the experiments described in this paper, a novel in vivo/in vitro preparation of adult rat S1 was used to determine changes in local circuit properties associated with the denervation-induced plasticity of the cortical representation in rat S1. In the present studies, deafferentation of rat S1 was induced by cutting the radial and median nerves in the forelimb of adult rats, resulting in a rapid shift of the location of the forepaw/lower jaw border; the amount of the shift increased over the times assayed, through 28 days after denervation. The locations of both borders (i.e., original and reorganized) were marked with vital dyes, and slices from the marked region were used for whole-cell recording. Responses were evoked using electrical stimulation of supragranular S1 and recorded in supragranular neurons close to either the original or reorganized border. For each neuron, postsynaptic potentials (PSPs) were evoked by stimulation of fibers that crossed the border site (CB stim) and by equivalent stimulation that did not cross (NCB stim). Monosynaptic inhibitory postsynaptic potentials (IPSPs) were also examined after blocking excitatory transmission with 15 microM CNQX plus 100 microM DL-APV. The amplitudes of PSPs and IPSPs were compared between CB and NCB stimulation to quantify effects of the border sites on excitation and inhibition. Previous results using this preparation in the normal (i.e., without induced plasticity) rat S1 demonstrated that at a normal border both PSPs and IPSPs were smaller when evoked with CB stimulation than with NCB stimulation. For most durations of denervation, a similar bias (i.e., smaller responses with CB stimulation) for PSPs and IPSPs was observed at the site of the novel reorganized border, while no such bias was observed at the suppressed original border site. Thus changes in local circuit properties (excitation and inhibition) can reflect larger-scale changes in cortical organization. However, specific dissociations between these local circuit properties and the presence of the novel border at certain durations of denervation were also observed, suggesting that there are several intracortical processes contributing to cortical reorganization over time and that excitation and inhibition may contribute differentially to them.
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Affiliation(s)
- Peter W Hickmott
- Department of Psychology, University of California, Riverside 92521, USA.
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Grachev ID, Apkarian AV. Chemical network of the living human brain. Evidence of reorganization with aging. BRAIN RESEARCH. COGNITIVE BRAIN RESEARCH 2001; 11:185-97. [PMID: 11275481 DOI: 10.1016/s0926-6410(00)00068-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
We recently described the chemical network properties of the human brain using in vivo proton magnetic resonance spectroscopy ((1)H MRS). In a separate study of aging we found increased concentration of chemicals in the prefrontal and sensorimotor cortices up to the third decade of life, and subsequent decrease of chemical concentrations in the same brain regions after the third decade between young and middle age. We anticipated that these age-dependent differences in chemical concentrations might be a reflection of the chemical network reorganization of the brain during aging. The pattern of chemical connectivity within and across brain regions for all regional chemicals, and specific patterns of chemical connectivity for each chemical type were examined for young and middle age groups using (1)H MRS and correlation analysis. For all studied ages, the dominant positive correlations occurred within brain regions and negative correlations were seen across brain regions. However, the pattern of negative chemical connectivity across brain regions was weaker in middle-aged group (F = 40.4, P < 10(-7) comparing r-values between the two age groups, ANOVA). Within brain regions, the age effects on chemical correlations were seen in the cingulate cortex (46% decrease in the middle-aged group, F = 7.2, P < 0.007) and sensorimotor cortex (SMC) (27% decrease, F = 8.9, P<0.003). Between brain regions, the age effects on chemical correlations were seen in the chemical interactions between the thalamus (433.3% increase in the middle-aged group, F = 11.7, P < 0.003), SMC (280% increase, F=20.1, P < 10(-5)), cingulate cortex (100.7% increase, F = 21.3, P < 10(-7)), and other brain regions. We found also age-differential patterns of chemical connectivity across the studied brain regions for most chemical types. The results provide evidence that normal aging is associated with reorganization of chemical network of the human brain.
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Affiliation(s)
- I D Grachev
- Department of Radiology, SUNY Upstate Medical University, 750 E. Adams Street, IHP 4109, Syracuse, NY 13210, USA.
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Neto FL, Schadrack J, Platzer S, Zieglgänsberger W, Tölle TR, Castro-Lopes JM. Up-regulation of metabotropic glutamate receptor 3 mRNA expression in the cerebral cortex of monoarthritic rats. J Neurosci Res 2001; 63:356-67. [PMID: 11170186 DOI: 10.1002/1097-4547(20010215)63:4<356::aid-jnr1030>3.0.co;2-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Metabotropic glutamate receptors (mGluR) have been shown to play a role in the modulation of acute and inflammatory pain. Additionally, we have recently detected time-dependent changes in the mRNA expression of several mGluR subtypes in thalamic nuclei of monoarthritic (MA) rats. In the present study, mGluR1, -3, -4, and -7 subtype mRNA expression was analyzed by in situ hybridization with radioactively labelled oligonucleotide probes in cerebral cortical regions of normal and MA rats at 2, 4, and 14 days of the disease. The mGluR1, -4, and -7 mRNAs were at background level in normal rats and did not change in MA animals. In contrast, mGluR3 mRNA expression was abundant in normal rats and was significantly increased in cortical areas of MA rats at all time points. Higher changes were detected bilaterally at 4 days, predominantly in layers IV/V, in the motor, primary, and secondary somatosensory cortices (average increases of 50-75%), but maximum rises occurred in the contralateral cingulate cortex (+138%). No changes were detected in the auditory cortex. The present data show an up-regulation of mGluR3 mRNA expression in the motor, somatosensory, and limbic cortices of MA rats. This possibly reflects the occurrence of central mechanisms counteracting the increased transmission of nociceptive input arising from the inflamed paw and the impaired motor behavior of these rats. Changes in the cingulate cortex may be related to the motivational-affective component of nociception.
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Affiliation(s)
- F L Neto
- Institute of Histology and Embryology and IBMC, Faculty of Medicine of Oporto, Porto, Portugal
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Higley MJ, Hermer-Vazquez L, Levitsky DA, Strupp BJ. Recovery of associative function following early amygdala lesions in rats. Behav Neurosci 2001; 115:154-64. [PMID: 11256439 DOI: 10.1037/0735-7044.115.1.154] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Adult rats with amygdala lesions made at either Postnatal Day (PND) 10 or PND40 were tested on a series of reversal tasks that tap the ability to form stimulus-reward associations. PND40 rats were significantly impaired relative to both controls and PND10 rats on learning rate of the original discrimination and subsequent reversals. Analyses of discrete learning phases revealed that the impairment was specific to the postchance phase. The PND10 group was not impaired relative to controls on any measure. These results confirm prior findings that amygdala lesions sustained in adulthood impair the formation of stimulus-reward associations. They also demonstrate that substantial sparing or recovery of function is possible when the lesion is made during early development. Furthermore, the findings support the view that behavioral recovery may be more likely if the lesion is sustained near the time of peak synaptogenesis.
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Affiliation(s)
- M J Higley
- Department of Psychology, Cornell University, USA
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Arckens L, Schweigart G, Qu Y, Wouters G, Pow DV, Vandesande F, Eysel UT, Orban GA. Cooperative changes in GABA, glutamate and activity levels: the missing link in cortical plasticity. Eur J Neurosci 2000; 12:4222-32. [PMID: 11122334 DOI: 10.1046/j.0953-816x.2000.01328.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Different intracortical mechanisms have been reported to contribute to the substantial topographic reorganization of the mammalian primary visual cortex in response to matching lesions in the two retinas: an immediate expansion of receptive fields followed by a gradual shift of excitability into the deprived area and finally axonal sprouting of laterally projecting neurons months after the lesion. To gain insight into the molecular mechanisms of this adult plasticity, we used immunocytochemical and bioanalytical methods to measure the glutamate and GABA neurotransmitter levels in the visual cortex of adult cats with binocular central retinal lesions. Two to four weeks after the lesions, glutamate immunoreactivity was decreased in sensory-deprived cortex as confirmed by HPLC analysis of the glutamate concentration. Within three months normal glutamate immunoreactivity was restored. In addition, the edge of the unresponsive cortex was characterized by markedly increased glutamate immunoreactivity 2-12 weeks postlesion. This glutamate immunoreactivity peak moved into the deprived area over time. These glutamate changes corresponded to decreased spontaneous and visually driven activity in unresponsive cortex and to strikingly increased neuronal activity at the border of this cortical zone. Furthermore, the previously reported decrease in glutamic acid decarboxylase immunoreactivity was found to reflect decreased GABA levels in sensory-deprived cortex. Increased glutamate concentrations and neuronal activity, and decreased GABA concentrations, may be related to changes in synaptic efficiency and could represent a mechanism underlying the retinotopic reorganization that occurs well after the immediate receptive field expansion but long before the late axonal sprouting.
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Affiliation(s)
- L Arckens
- Laboratory of Neuroendocrinology and Immunological Biotechnology, Katholieke Universiteit Leuven, Naamsestraat 59, B-3000 Leuven, Belgium.
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Abstract
We studied coactivation-based cortical plasticity at a psychophysical level in humans. For induction of plasticity, we used a protocol of simultaneous pairing of tactile stimulation to follow as closely as possible the idea of Hebbian learning. We reported previously that a few hours of tactile coactivation resulted in selective and reversible reorganization of receptive fields and cortical maps of the hindpaw representation of the somatosensory cortex of adult rats (Godde et al., 1996). In the present study, simultaneous spatial two-point discrimination was tested on the tip of the right index finger in human subjects as a marker of plastic changes. After 2 hr of coactivation we found a significant improvement in discrimination performance that was reversible within 8 hr. Reduction of the duration of the coactivation protocol revealed that 30 min was not sufficient to drive plastic changes. Repeated application of coactivation over 3 consecutive days resulted in a delayed recovery indicating stabilization of the improvement over time. Perceptual changes were highly selective because no transfer of improved performance to fingers that were not stimulated was found. The results demonstrate the potential role of sensory input statistics (i.e., their probability of occurrence and spatiotemporal relationships) in the induction of cortical plasticity without involving cognitive factors such as attention or reinforcement.
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Godde B, Stauffenberg B, Spengler F, Dinse HR. Tactile coactivation-induced changes in spatial discrimination performance. J Neurosci 2000; 20:1597-604. [PMID: 10662849 PMCID: PMC6772356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023] Open
Abstract
We studied coactivation-based cortical plasticity at a psychophysical level in humans. For induction of plasticity, we used a protocol of simultaneous pairing of tactile stimulation to follow as closely as possible the idea of Hebbian learning. We reported previously that a few hours of tactile coactivation resulted in selective and reversible reorganization of receptive fields and cortical maps of the hindpaw representation of the somatosensory cortex of adult rats (Godde et al., 1996). In the present study, simultaneous spatial two-point discrimination was tested on the tip of the right index finger in human subjects as a marker of plastic changes. After 2 hr of coactivation we found a significant improvement in discrimination performance that was reversible within 8 hr. Reduction of the duration of the coactivation protocol revealed that 30 min was not sufficient to drive plastic changes. Repeated application of coactivation over 3 consecutive days resulted in a delayed recovery indicating stabilization of the improvement over time. Perceptual changes were highly selective because no transfer of improved performance to fingers that were not stimulated was found. The results demonstrate the potential role of sensory input statistics (i.e., their probability of occurrence and spatiotemporal relationships) in the induction of cortical plasticity without involving cognitive factors such as attention or reinforcement.
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Affiliation(s)
- B Godde
- Institute of Medical Psychology, University of Tübingen, 72074 Tübingen, Germany.
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