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Koehler S, Hasselmann E, Wüstenberg T, Heinz A, Romanczuk-Seiferth N. Higher volume of ventral striatum and right prefrontal cortex in pathological gambling. Brain Struct Funct 2013; 220:469-77. [DOI: 10.1007/s00429-013-0668-6] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Accepted: 10/29/2013] [Indexed: 01/25/2023]
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Berman BD, Hallett M, Herscovitch P, Simonyan K. Striatal dopaminergic dysfunction at rest and during task performance in writer's cramp. ACTA ACUST UNITED AC 2013; 136:3645-58. [PMID: 24148273 DOI: 10.1093/brain/awt282] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Writer's cramp is a task-specific focal hand dystonia characterized by involuntary excessive muscle contractions during writing. Although abnormal striatal dopamine receptor binding has been implicated in the pathophysiology of writer's cramp and other primary dystonias, endogenous dopamine release during task performance has not been previously investigated in writer's cramp. Using positron emission tomography imaging with the D2/D3 antagonist 11C-raclopride, we analysed striatal D2/D3 availability at rest and endogenous dopamine release during sequential finger tapping and speech production tasks in 15 patients with writer's cramp and 15 matched healthy control subjects. Compared with control subjects, patients had reduced 11C-raclopride binding to D2/D3 receptors at rest in the bilateral striatum, consistent with findings in previous studies. During the tapping task, patients had decreased dopamine release in the left striatum as assessed by reduced change in 11C-raclopride binding compared with control subjects. One cluster of reduced dopamine release in the left putamen during tapping overlapped with a region of reduced 11C-raclopride binding to D2/D3 receptors at rest. During the sentence production task, patients showed increased dopamine release in the left striatum. No overlap between altered dopamine release during speech production and reduced 11C-raclopride binding to D2/D3 receptors at rest was seen. Striatal regions where D2/D3 availability at rest positively correlated with disease duration were lateral and non-overlapping with striatal regions showing reduced D2/D3 receptor availability, except for a cluster in the left nucleus accumbens, which showed a negative correlation with disease duration and overlapped with striatal regions showing reduced D2/D3 availability. Our findings suggest that patients with writer's cramp may have divergent responses in striatal dopamine release during an asymptomatic motor task involving the dystonic hand and an unrelated asymptomatic task, sentence production. Our voxel-based results also suggest that writer's cramp may be associated with reduced striatal dopamine release occuring in the setting of reduced D2/D3 receptor availability and raise the possibility that basal ganglia circuits associated with premotor cortices and those associated with primary motor cortex are differentially affected in primary focal dystonias.
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Affiliation(s)
- Brian D Berman
- 1 Department of Neurology, University of Colorado Anschutz Medical Campus, Denver, CO USA
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Roldan-Valadez E, Rios C, Suarez-May MA, Favila R, Aguilar-Castañeda E. Main effect and interactions of brain regions and gender in the calculation of volumetric asymmetry indices in healthy human brains: ANCOVA analyses of in vivo 3T MRI data. Anat Rec (Hoboken) 2013; 296:1913-22. [PMID: 24136790 DOI: 10.1002/ar.22817] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Revised: 08/12/2013] [Accepted: 08/14/2013] [Indexed: 02/05/2023]
Abstract
INTRODUCTION Macroanatomical right-left hemispheric differences in the brain are termed asymmetries, although there is no clear information on the global influence of gender and brain-regions. The aim of this study was to evaluate the main effects and interactions of these variables on the measurement of volumetric asymmetry indices (VAIs). MATERIALS AND METHODS Forty-seven healthy young-adult volunteers (23 males, 24 females) agreed to undergo brain magnetic resonance imaging in a 3T scanner. Image post processing using voxel-based volumetry allowed the calculation of 54 VAIs from the frontal, temporal, parietal and occipital lobes, limbic system, basal ganglia, and cerebellum for each cerebral hemisphere. Multivariate ANCOVA analysis calculated the main effects and interactions on VAIs of gender and brain regions controlling the effect of age. RESULTS The only significant finding was the main effect of brain regions (F (6, 9373.605) 44.369, P < .001; partial η2 = .101, and power of 1.0), with no significant interaction between gender and brain regions (F (6, 50.517) .239, P = .964). CONCLUSION Volumetric asymmetries are present across all brain regions, with larger values found in the limbic system and parietal lobe. The absence of a significant influence of gender and age in the evaluation of the numerous measurements generated by multivariate analyses in this study should not discourage researchers to report and interpret similar results, as this topic still deserves further assessment.
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Kreifelts B, Jacob H, Brück C, Erb M, Ethofer T, Wildgruber D. Non-verbal emotion communication training induces specific changes in brain function and structure. Front Hum Neurosci 2013; 7:648. [PMID: 24146641 PMCID: PMC3797968 DOI: 10.3389/fnhum.2013.00648] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2013] [Accepted: 09/18/2013] [Indexed: 01/20/2023] Open
Abstract
The perception of emotional cues from voice and face is essential for social interaction. However, this process is altered in various psychiatric conditions along with impaired social functioning. Emotion communication trainings have been demonstrated to improve social interaction in healthy individuals and to reduce emotional communication deficits in psychiatric patients. Here, we investigated the impact of a non-verbal emotion communication training (NECT) on cerebral activation and brain structure in a controlled and combined functional magnetic resonance imaging (fMRI) and voxel-based morphometry study. NECT-specific reductions in brain activity occurred in a distributed set of brain regions including face and voice processing regions as well as emotion processing- and motor-related regions presumably reflecting training-induced familiarization with the evaluation of face/voice stimuli. Training-induced changes in non-verbal emotion sensitivity at the behavioral level and the respective cerebral activation patterns were correlated in the face-selective cortical areas in the posterior superior temporal sulcus and fusiform gyrus for valence ratings and in the temporal pole, lateral prefrontal cortex and midbrain/thalamus for the response times. A NECT-induced increase in gray matter (GM) volume was observed in the fusiform face area. Thus, NECT induces both functional and structural plasticity in the face processing system as well as functional plasticity in the emotion perception and evaluation system. We propose that functional alterations are presumably related to changes in sensory tuning in the decoding of emotional expressions. Taken together, these findings highlight that the present experimental design may serve as a valuable tool to investigate the altered behavioral and neuronal processing of emotional cues in psychiatric disorders as well as the impact of therapeutic interventions on brain function and structure.
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Affiliation(s)
- Benjamin Kreifelts
- Department of Psychiatry and Psychotherapy, Eberhard Karls University of Tübingen Tübingen, Germany
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Allen JS, Emmorey K, Bruss J, Damasio H. Neuroanatomical differences in visual, motor, and language cortices between congenitally deaf signers, hearing signers, and hearing non-signers. Front Neuroanat 2013; 7:26. [PMID: 23935567 PMCID: PMC3731534 DOI: 10.3389/fnana.2013.00026] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2013] [Accepted: 07/19/2013] [Indexed: 11/13/2022] Open
Abstract
WE INVESTIGATED EFFECTS OF SIGN LANGUAGE USE AND AUDITORY DEPRIVATION FROM BIRTH ON THE VOLUMES OF THREE CORTICAL REGIONS OF THE HUMAN BRAIN: the visual cortex surrounding the calcarine sulcus in the occipital lobe; the language-related cortex in the inferior frontal gyrus (pars triangularis and pars opercularis); and the motor hand region in the precentral gyrus. The study included 25 congenitally deaf participants and 41 hearing participants (of which 16 were native sign language users); all were right-handed. Deaf participants exhibited a larger calcarine volume than hearing participants, which we interpret as the likely result of cross-modal compensation and/or dynamic interactions within sensory neural networks. Deaf participants also had increased volumes of the pars triangularis bilaterally compared to hearing signers and non-signers, which we interpret is related to the increased linguistic demands of speech processing and/or text reading for deaf individuals. Finally, although no statistically significant differences were found in the motor hand region for any of the groups, the deaf group was leftward asymmetric, the hearing signers essentially symmetric and the hearing non-signers were rightward asymmetric - results we interpret as the possible result of activity-dependent change due to life-long signing. The brain differences we observed in visual, motor, and language-related areas in adult deaf native signers provide evidence for the plasticity available for cognitive adaptation to varied environments during development.
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Affiliation(s)
- John S Allen
- Dornsife Cognitive Neuroscience Imaging Center, University of Southern California Los Angeles, CA, USA ; Brain and Creativity Institute, University of Southern California Los Angeles, CA, USA
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Dong M, Qin W, Zhao L, Yang X, Yuan K, Zeng F, Sun J, Yu D, von Deneen KM, Liang F, Tian J. Expertise modulates local regional homogeneity of spontaneous brain activity in the resting brain: an fMRI study using the model of skilled acupuncturists. Hum Brain Mapp 2013; 35:1074-84. [PMID: 23633412 DOI: 10.1002/hbm.22235] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Revised: 10/29/2012] [Accepted: 11/07/2012] [Indexed: 11/08/2022] Open
Abstract
Studies on training/expertise-related effects on human brain in context of neuroplasticity have revealed that plastic changes modulate not only task activations but also patterns and strength of internetworks and intranetworks functional connectivity in the resting state. Much has known about plastic changes in resting state on global level; however, how training/expertise-related effect affects patterns of local spontaneous activity in resting brain remains elusive. We investigated the homogeneity of local blood oxygen level-dependent fluctuations in the resting state using a regional homogeneity (ReHo) analysis among 16 acupuncturists and 16 matched nonacupuncturists (NA). To prove acupuncturists' expertise, we used a series of psychophysical tests. Our results demonstrated that, acupuncturists significantly outperformed NA in tactile-motor and emotional regulation domain and the acupuncturist group showed increased coherence in local BOLD signal fluctuations in the left primary motor cortex (MI), the left primary somatosensory cortex (SI) and the left ventral medial prefrontal cortex/orbitofrontal cortex (VMPFC/OFC). Regression analysis displayed that, in the acupuncturists group, ReHo of VMPFC/OFC could predict behavioral outcomes, evidenced by negative correlation between unpleasantness ratings and ReHo of VMPFC/OFC and ReHo of SI and MI positively correlated with the duration of acupuncture practice. We suggest that expertise could modulate patterns of local resting state activity by increasing regional clustering strength, which is likely to contribute to advanced local information processing efficiency. Our study completes the understanding of neuroplasticity changes by adding the evidence of local resting state activity alterations, which is helpful for elucidating in what manner training effect extends beyond resting state.
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Affiliation(s)
- Minghao Dong
- School of Life Sciences and Technology, Xidian University, Xi'an, Shaanxi, China
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Ramdhani RA, Simonyan K. Primary dystonia: conceptualizing the disorder through a structural brain imaging lens. TREMOR AND OTHER HYPERKINETIC MOVEMENTS (NEW YORK, N.Y.) 2013; 3. [PMID: 23610744 PMCID: PMC3629863 DOI: 10.7916/d8h70dj7] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Accepted: 03/08/2013] [Indexed: 12/14/2022]
Abstract
Background Dystonia is a hyperkinetic movement disorder characterized by involuntary, repetitive twisting movements. The anatomical structures and pathways implicated in its pathogenesis and their relationships to the neurophysiological paradigms of abnormal surround inhibition, maladaptive plasticity, and impaired sensorimotor integration remain unclear. Objective We review the use of high-resolution structural brain imaging using voxel-based morphometry (VBM) and diffusion tensor imaging (DTI) techniques for evaluating brain changes in primary torsion dystonia and their relationships to the pathophysiology of this disorder. Methods A PubMed search was conducted to identify relevant literature. Results VBM and DTI studies produced somewhat conflicting results across different forms of primary dystonia and reported increases, decreases, or both in gray matter volume and white matter integrity. However, despite the discrepancies, these studies are consistent in revealing brain abnormalities in dystonia that extend beyond the basal ganglia and involve the sensorimotor cortex and cerebellum. Discussion Although limited to date, structural magnetic resonance imaging (MRI) studies combined with functional brain imaging and neurophysiological modalities begin to establish structural-functional relationships at different levels of the abnormal basal ganglia, cortical, and cerebellar networks and provide clues into the pathophysiological mechanisms that underlie primary dystonia. Cross-disciplinary studies are needed for further investigations of the interplay between structural-functional brain abnormalities and environmental and genetic risk factors in dystonia patients.
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Affiliation(s)
- Ritesh A Ramdhani
- Departments of Neurology, Icahn School of Medicine at Mount Sinai, New York, New York 10029, United States of America
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Lövdén M, Wenger E, Mårtensson J, Lindenberger U, Bäckman L. Structural brain plasticity in adult learning and development. Neurosci Biobehav Rev 2013; 37:2296-310. [PMID: 23458777 DOI: 10.1016/j.neubiorev.2013.02.014] [Citation(s) in RCA: 170] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Revised: 02/04/2013] [Accepted: 02/19/2013] [Indexed: 12/31/2022]
Abstract
Recent research using magnetic resonance imaging has documented changes in the adult human brain's grey matter structure induced by alterations in experiential demands. We review this research and relate it to models of brain plasticity from related strands of research, such as work on animal models. This allows us to generate recommendations and predictions for future research that may advance the understanding of the function, sequential progression, and microstructural nature of experience-dependent changes in regional brain volumes. Informed by recent evidence on adult age differences in structural brain plasticity, we show how understanding learning-related changes in human brain structure can expand our knowledge about adult development and aging. We hope that this review will promote research on the mechanisms regulating experience-dependent structural plasticity of the adult human brain.
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Affiliation(s)
- Martin Lövdén
- Aging Research Center, Karolinska Institutet & Stockholm University, Gävlegatan 16, 113 30 Stockholm, Sweden; Center for Lifespan Psychology, Max Planck Institute for Human Development, Lentzeallee 94, 14195 Berlin, Germany.
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Mastroeni C, Bergmann TO, Rizzo V, Ritter C, Klein C, Pohlmann I, Brueggemann N, Quartarone A, Siebner HR. Brain-derived neurotrophic factor--a major player in stimulation-induced homeostatic metaplasticity of human motor cortex? PLoS One 2013; 8:e57957. [PMID: 23469118 PMCID: PMC3585283 DOI: 10.1371/journal.pone.0057957] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 01/29/2013] [Indexed: 01/24/2023] Open
Abstract
Repetitive transcranial magnetic stimulation (rTMS) of the human motor hand area (M1HAND) can induce lasting changes in corticospinal excitability as indexed by a change in amplitude of the motor-evoked potential. The plasticity-inducing effects of rTMS in M1HAND show substantial inter-individual variability which has been partially attributed to the val66met polymorphism in the brain-derived neurotrophic factor (BDNF) gene. Here we used theta burst stimulation (TBS) to examine whether the BDNF val66met genotype can be used to predict the expression of TBS-induced homeostatic metaplasticity in human M1HAND. TBS is a patterned rTMS protocol with intermittent TBS (iTBS) usually inducing a lasting increase and continuous TBS (cTBS) a lasting decrease in corticospinal excitability. In three separate sessions, healthy val66met (n = 12) and val66val (n = 17) carriers received neuronavigated cTBS followed by cTBS (n = 27), cTBS followed by iTBS (n = 29), and iTBS followed by iTBS (n = 28). Participants and examiner were blinded to the genotype at the time of examination. As expected, the first TBS intervention induced a decrease (cTBS) and increase (iTBS) in corticospinal excitability, respectively, at the same time priming the after effects caused by the second TBS intervention in a homeostatic fashion. Critically, val66met carriers and val66val carriers showed very similar response patterns to cTBS and iTBS regardless of the order of TBS interventions. Since none of the observed TBS effects was modulated by the BDNF val66met polymorphism, our results do not support the notion that the BDNF val66met genotype is a major player with regard to TBS-induced plasticity and metaplasticity in the human M1HAND.
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Affiliation(s)
- Claudia Mastroeni
- Department of Neurology, Christian-Albrechts-University, Kiel, Germany
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Yoo K, Sohn WS, Jeong Y. Tool-use practice induces changes in intrinsic functional connectivity of parietal areas. Front Hum Neurosci 2013; 7:49. [PMID: 23550165 PMCID: PMC3582314 DOI: 10.3389/fnhum.2013.00049] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Accepted: 02/05/2013] [Indexed: 11/13/2022] Open
Abstract
Intrinsic functional connectivity from resting state functional magnetic resonance imaging (rsfMRI) has increasingly received attention as a possible predictor of cognitive function and performance. In this study, we investigated the influence of practicing skillful tool manipulation on intrinsic functional connectivity in the resting brain. Acquisition of tool-use skill has two aspects such as formation of motor representation for skillful manipulation and acquisition of the tool concept. To dissociate these two processes, we chose chopsticks-handling with the non-dominant hand. Because participants were already adept at chopsticks-handling with their dominant hand, practice with the non-dominant hand involved only acquiring the skill for tool manipulation with existing knowledge. Eight young participants practiced chopsticks-handling with their non-dominant hand for 8 weeks. They underwent functional magnetic resonance imaging (fMRI) sessions before and after the practice. As a result, functional connectivity among tool-use-related regions of the brain decreased after practice. We found decreased functional connectivity centered on parietal areas, mainly the supramarginal gyrus (SMG) and superior parietal lobule (SPL) and additionally between the primary sensorimotor area and cerebellum. These results suggest that the parietal lobe and cerebellum purely mediate motor learning for skillful tool-use. This decreased functional connectivity may represent increased efficiency of functional network.
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Affiliation(s)
- Kwangsun Yoo
- Laboratory for Cognitive Neuroscience and NeuroImaging, Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology Daejeon, South Korea
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Lou AR, Madsen KH, Julian HO, Toft PB, Kjaer TW, Paulson OB, Prause JU, Siebner HR. Postoperative increase in grey matter volume in visual cortex after unilateral cataract surgery. Acta Ophthalmol 2013; 91:58-65. [PMID: 22103594 DOI: 10.1111/j.1755-3768.2011.02304.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE The developing visual cortex has a strong potential to undergo plastic changes. Little is known about the potential of the ageing visual cortex to express plasticity. A pertinent question is whether therapeutic interventions can trigger plastic changes in the ageing visual cortex by restoring vision. METHODS Twelve patients aged 50-85 years underwent structural high-resolution T1-weighted MRI of the whole brain 2 days and 6 weeks after unilateral cataract surgery. Voxel-based morphometry (VBM) based on T1-weighted magnetic resonance imaging (MRI) was employed to test whether cataract surgery induces a regional increase in grey matter in areas V1 and V2 of the visual cortex. RESULTS In all patients, cataract surgery immediately improved visual acuity, contrast sensitivity and mean sensitivity in the visual field of the operated eye. The improvement in vision was stable throughout the 6 weeks after operation. VBM revealed a regional expansion of grey matter volume in area V2 contralateral to the operated eye during the 6-week period after surgery. Individual increases in grey matter were predicted by the symmetry in visual acuity between the operated eye and nonoperated eye. The more symmetrical visual acuity became after unilateral cataract surgery, the more pronounced was the grey matter increase in visual cortex. CONCLUSION The data suggest that cataract surgery triggered a use-dependent structural plasticity in V2 presumably through improved binocular integration of visual input from both eyes. We conclude that activity-dependent cortical plasticity is preserved in the ageing visual cortex and may be triggered by restoring impaired vision.
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Affiliation(s)
- Astrid R Lou
- Department of Ophthalmology, Copenhagen University Hospital Glostrup, Glostrup Hospital, Copenhagen, Denmark
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Rostami HR, Arefi A, Tabatabaei S. Effect of mirror therapy on hand function in patients with hand orthopaedic injuries: a randomized controlled trial. Disabil Rehabil 2013; 35:1647-51. [DOI: 10.3109/09638288.2012.751132] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Freund P, Schneider T, Nagy Z, Hutton C, Weiskopf N, Friston K, Wheeler-Kingshott CA, Thompson AJ. Degeneration of the injured cervical cord is associated with remote changes in corticospinal tract integrity and upper limb impairment. PLoS One 2012; 7:e51729. [PMID: 23251612 PMCID: PMC3520920 DOI: 10.1371/journal.pone.0051729] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2012] [Accepted: 11/05/2012] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Traumatic spinal cord injury (SCI) leads to disruption of axons and macroscopic tissue loss. Using diffusion tensor imaging (DTI), we assessed degeneration of the corticospinal tract (CST) in the cervical cord above a traumatic lesion and explored its relationship with cervical atrophy, remote axonal changes within the cranial CST and upper limb function. METHODS Nine cervical injured volunteers with bilateral motor and sensory impairment and ten controls were studied. DTI of the cervical cord and brain provided measurements of fractional anisotropy (FA), while anatomical MRI assessed cross-sectional spinal cord area (i.e. cord atrophy). Spinal and central regions of interest (ROI) included the bilateral CST in the cervical cord and brain. Regression analysis identified correlations between spinal FA and cranial FA in the CST and disability. RESULTS In individuals with SCI, FA was significantly lower in both CSTs throughout the cervical cord and brain when compared with controls (p≤0.05). Reduced FA of the cervical cord in patients with SCI was associated with smaller cord area (p = 0.002) and a lower FA of the cranial CST at the internal capsule level (p = 0.001). Lower FA in the cervical CST also correlated with impaired upper limb function, independent of cord area (p = 0.03). CONCLUSION Axonal degeneration of the CST in the atrophic cervical cord, proximal to the site of injury, parallels cranial CST degeneration and is associated with disability. This DTI protocol can be used in longitudinal assessment of microstructural changes immediately following injury and may be utilised to predict progression and monitor interventions aimed at promoting spinal cord repair.
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Affiliation(s)
- Patrick Freund
- Department of Brain Repair and Rehabilitation, University College London Institute of Neurology, University College London, London, United Kingdom.
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Abstract
PURPOSE OF REVIEW This review considers the recent literature pertaining to the clinical features, genetics, neuropathology and treatment of dystonia syndromes. RECENT FINDINGS The term dystonia indicates at the same time a clinical phenotype and a collection of neurological syndromes mainly of genetic origin. The physical signs contributing to the phenomenology of dystonia have been recently assembled into a coherent set. The molecular genetics of primary dystonia syndromes (DYT1 and DYT6) have been the object of extensive analysis, providing converging views on their causative mechanisms. The relationship between genotype, phenotype, and endophenotypes has been explored for hereditary and sporadic dystonia syndromes. Neurophysiological studies on DYT1 and DYT6 patients, as well as on nonmanifesting carriers, have demonstrated the presence of altered synaptic plasticity. Several recent data indicate a role of dopamine and acetylcholine (ACh) transmission in the pathophysiology of primary dystonia. SUMMARY Recent findings have led to novel, testable hypotheses on cellular mechanisms and physiopathological abnormalities underlying dystonia. Neurophysiological studies, imaging data and animal models support the view that corticostriatal, cerebellar, and dopaminergic dysfunctions converge to produce the pathophysiological abnormalities of dystonia.
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Roll R, Kavounoudias A, Albert F, Legré R, Gay A, Fabre B, Roll J. Illusory movements prevent cortical disruption caused by immobilization. Neuroimage 2012; 62:510-9. [DOI: 10.1016/j.neuroimage.2012.05.016] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Revised: 02/06/2012] [Accepted: 05/06/2012] [Indexed: 11/17/2022] Open
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Ngomo S, Leonard G, Mercier C. Influence of the amount of use on hand motor cortex representation: effects of immobilization and motor training. Neuroscience 2012; 220:208-14. [PMID: 22710067 DOI: 10.1016/j.neuroscience.2012.06.018] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Revised: 05/31/2012] [Accepted: 06/07/2012] [Indexed: 10/28/2022]
Abstract
Converging evidence from animal and human studies has revealed that increased or decreased use of an extremity can lead to changes in cortical representation of the involved muscles. However, opposite experimental manipulations such as immobilization and motor training have sometimes been associated with similar cortical changes. Therefore, the behavioral relevance of these changes remains unclear. The purpose of this study was to observe the effect of the amount of use on hand muscle motor cortex representation by contrasting the effect of unspecific motor training and immobilization. Nine healthy volunteers were tested prior and after a 4-day exposure to two experimental conditions using a randomized cross-over design: a motor training condition (to play Guitar Hero 2h/day with the tested (nondominant) hand on the fret board) and an immobilization condition (to wear an immobilization splint 24h/day). Before and after each condition, motor cortex representation of the nondominant first dorsal interosseous (FDI) muscle was mapped using image-guided transcranial magnetic stimulation (TMS). At the behavioral level, results show that the training condition led to a 20% improvement in the trained task, while the immobilization condition resulted in a 36% decrease in the FDI maximal voluntary contraction. At the neurophysiological level, corticospinal excitability (e.g. Motor-evoked potential amplitude) was found to be decreased in response to immobilization, while no change was observed in response to motor training. No change was found for other TMS variables (motor thresholds or map location/volume/area) in either condition. In conclusion, our results indicate that a 4-day decrease, but not increase, in the amount of use of nondominant hand muscles is sufficient to induce a change in corticospinal excitability. The lack of a training effect might be explained by the use of an unspecific task (that is nevertheless representative of "real-life" training situations) and/or by insufficient duration/intensity to induce long-lasting changes.
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Affiliation(s)
- S Ngomo
- Centre interdisciplinaire de recherche en réadaptation et en intégration sociale (CIRRIS), Canada
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Lioumis P, Mustanoja S, Bikmullina R, Vitikainen AM, Kičić D, Salonen O, Tatlisumak T, Kaste M, Forss N, Mäkelä JP. Probing modifications of cortical excitability during stroke recovery with navigated transcranial magnetic stimulation. Top Stroke Rehabil 2012; 19:182-92. [PMID: 22436366 DOI: 10.1310/tsr1902-182] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE To follow cortical excitability changes during recovery from stroke with navigated transcranial magnetic stimulation (nTMS), in particular, to characterize changes of short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF), to correlate them with recovery of upper extremity function, and to detect possible shifts of cortical hand representations. METHODS Single and paired pulse nTMS were delivered to the hemisphere with infarction and to the hemisphere without infarction in 14 first-ever stroke patients at 1 (T1) and 3 months (T2) after stroke. Electromyographic responses to nTMS stimulation were recorded from the first dorsal interosseus muscles. nTMS was used to ensure an accurate coil repositioning in repeated measurements. Hand function recovery was clinically evaluated using the Action Research Arm Test (ARAT) and 9-hole peg test (9-HPT). RESULTS SICI and ICF were modulated in both hemispheres during recovery. Inhibition in the hemisphere without infarction correlated significantly with the affected hand performance at T2; stronger disinhibition (poor inhibition) was associated with worse hand performance. Location of hand muscle representations was shifted in 3 well-recovered patients out of 14 patients at T2. CONCLUSIONS In line with earlier studies, disinhibition in the hemisphere without infarction may be related to poor recovery of the affected hand. Usage of the affected hand during stroke recovery seems to influence these cortical excitability changes. nTMS is a valuable tool for tracking muscle cortical representation changes during brain reorganization.
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Sun ZY, Klöppel S, Rivière D, Perrot M, Frackowiak R, Siebner H, Mangin JF. The effect of handedness on the shape of the central sulcus. Neuroimage 2012; 60:332-9. [DOI: 10.1016/j.neuroimage.2011.12.050] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2011] [Revised: 12/04/2011] [Accepted: 12/18/2011] [Indexed: 12/21/2022] Open
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Delvendahl I, Jung NH, Kuhnke NG, Ziemann U, Mall V. Plasticity of motor threshold and motor-evoked potential amplitude--a model of intrinsic and synaptic plasticity in human motor cortex? Brain Stimul 2012; 5:586-93. [PMID: 22445536 DOI: 10.1016/j.brs.2011.11.005] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Revised: 11/21/2011] [Accepted: 11/22/2011] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Neuronal plasticity is the physiological correlate of learning and memory. In animal experiments, synaptic (i.e. long-term potentiation (LTP) and depression (LTD)) and intrinsic plasticity are distinguished. In human motor cortex, cortical plasticity can be demonstrated using transcranial magnetic stimulation (TMS). Changes in motor-evoked potential (MEP) amplitudes most likely represent synaptic plasticity and are thus termed LTP-like and LTD-like plasticity. OBJECTIVE/HYPOTHESIS We investigated the role of changes of motor threshold and their relation to changes of MEP amplitudes. METHODS We induced plasticity by paired associative stimulation (PAS) with 25 ms or 10 ms inter-stimulus interval or by motor practice (MP) in 64 healthy subjects aged 18-31 years (median 24.0). RESULTS We observed changes of MEP amplitudes and motor threshold after PAS[25], PAS[10] and MP. In all three protocols, long-term individual changes in MEP amplitude were inversely correlated to changes in motor threshold (PAS[25]: P = .003, n = 36; PAS[10]: P = .038, n = 19; MP: P = .041, n = 19). CONCLUSION We conclude that changes of MEP amplitudes and MT represent two indices of motor cortex plasticity. Whereas increases and decreases in MEP amplitude are assumed to represent LTP-like or LTD-like synaptic plasticity of motor cortex output neurons, changes of MT may be considered as a correlate of intrinsic plasticity.
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Affiliation(s)
- Igor Delvendahl
- Division of Neuropaediatrics and Muscular Disorders, Department of Paediatrics and Adolescent Medicine, University Medical Centre, Freiburg, Germany
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70
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Zheng Z, Pan P, Wang W, Shang H. Neural network of primary focal dystonia by an anatomic likelihood estimation meta-analysis of gray matter abnormalities. J Neurol Sci 2012; 316:51-5. [PMID: 22349356 DOI: 10.1016/j.jns.2012.01.032] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Revised: 01/21/2012] [Accepted: 01/31/2012] [Indexed: 02/05/2023]
Abstract
BACKGROUND Recent voxel-based morphometry (VBM) studies have found gray matter (GM) abnormalities in primary focal dystonia (PFD) and yielded inconsistent results. AIM Our aim is to investigate consistent GM changes in PFD and to identify whether different subtypes of PFD share a common pathophysiological basis revealed by structural abnormalities. METHODS A systematic search of VBM studies of patients with PFD and healthy control (HC) subjects published in PubMed, Embase, and Medline databases from January 1998 to April 2011 was conducted. We performed a voxel-wise meta-analysis of VBM studies comparing PFD to HC using the anatomic likelihood estimation (ALE) method. RESULTS A total of 9 articles, which reported 11 PFD-HC comparisons including 199 PFD patients and 247 HC subjects, met the inclusion criteria. GM volume (GMV) was found to be greater in the caudate, postcentral cortex (BA2, 3, 40) and primary motor cortex, and smaller in the thalamus and putamen. CONCLUSION Our findings provide evidence for structural abnormalities within the sensorimotor network involved in the pathophysiology of PFD. However, our work could not distinguish whether the brain structural changes are primary or secondary to PFD.
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Affiliation(s)
- ZhenZhen Zheng
- Department of Neurology, West China Hospital, Sichuan University, 610041, Chengdu, Sichuan, China
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71
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Wenger E, Schaefer S, Noack H, Kühn S, Mårtensson J, Heinze HJ, Düzel E, Bäckman L, Lindenberger U, Lövdén M. Cortical thickness changes following spatial navigation training in adulthood and aging. Neuroimage 2012; 59:3389-97. [DOI: 10.1016/j.neuroimage.2011.11.015] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Revised: 10/29/2011] [Accepted: 11/04/2011] [Indexed: 10/15/2022] Open
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72
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Bezzola L, Mérillat S, Jäncke L. Motor Training-Induced Neuroplasticity. GEROPSYCH-THE JOURNAL OF GERONTOPSYCHOLOGY AND GERIATRIC PSYCHIATRY 2012. [DOI: 10.1024/1662-9647/a000070] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The present lab-review presents and discusses our previous and current research into motor training-induced neuroplasticity by classifying our work on the basis of two broad aspects: (1) the applied study design (i.e., cross-sectional vs. longitudinal) and (2) the complexity of the motor task subjected to training (i.e., elementary finger movements vs. highly complex physical activity). Together with others we demonstrate that training-induced anatomic and functional changes are evident for a wide range of motor tasks and for several age cohorts. Finally, we discuss our findings from a lifespan perspective and embed them in the context of research investigating the beneficial effect of motor training-induced neuroplasticity on brain aging.
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Affiliation(s)
- Ladina Bezzola
- International Normal Aging and Plasticity Imaging Center (INAPIC), University of Zurich, Switzerland
- Division of Neuropsychology, Institute of Psychology, University of Zurich, Switzerland
| | - Susan Mérillat
- International Normal Aging and Plasticity Imaging Center (INAPIC), University of Zurich, Switzerland
| | - Lutz Jäncke
- International Normal Aging and Plasticity Imaging Center (INAPIC), University of Zurich, Switzerland
- Division of Neuropsychology, Institute of Psychology, University of Zurich, Switzerland
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73
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Abstract
The motor system has been intensively studied using the emerging neuroimaging technologies over the last twenty years. These include early applications of positron emission tomography of brain perfusion, metabolic rate and receptor function, as well as functional magnetic resonance imaging, tractography from diffusion weighted imaging, and transcranial magnetic stimulation. Motor system research has the advantage of the existence of extensive electrophysiological and anatomical information from comparative studies which enables cross-validation of new methods. We review the impact of neuroimaging on the understanding of diverse motor functions, including motor learning, decision making, inhibition and the mirror neuron system. In addition, we show how imaging of the motor system has supported a powerful platform for bidirectional translational neuroscience. In one direction, it has provided the opportunity to study safely the processes of neuroplasticity, neural networks and neuropharmacology in stroke and movement disorders and offers a sensitive tool to assess novel therapeutics. In the reverse direction, imaging of clinical populations has promoted innovations in cognitive theory, experimental design and analysis. We highlight recent developments in the analysis of structural and functional connectivity in the motor system; the advantages of integration of multiple methodologies; and new approaches to experimental design using formal models of cognitive-motor processes.
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75
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Thompson VB, Jinnah HA, Hess EJ. Convergent mechanisms in etiologically-diverse dystonias. Expert Opin Ther Targets 2011; 15:1387-403. [PMID: 22136648 DOI: 10.1517/14728222.2011.641533] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Dystonia is a neurological disorder associated with twisting motions and abnormal postures, which compromise normal movements and can be both painful and debilitating. It can affect a single body part (focal), several contiguous regions (segmental), or the entire body (generalized), and can arise as a result of numerous causes, both genetic and acquired. Despite the diversity of causes and manifestations, shared clinical features suggest that common mechanisms of pathogenesis may underlie many dystonias. AREAS COVERED Shared themes in etiologically-diverse dystonias exist at several biological levels. At the cellular level, abnormalities in the dopaminergic system, mitochondrial function and calcium regulation are often present. At the anatomical level, the basal ganglia and the cerebellum are frequently implicated. Global CNS dysfunction, specifically aberrant neuronal plasticity, inhibition and sensorimotor integration, are also observed in a number of dystonias. Using clinical data and data from animal models, this article seeks to highlight shared pathways that may be critical in understanding mechanisms and identifying novel therapeutic strategies in dystonia. EXPERT OPINION Identifying shared features of pathogenesis can provide insight into the biological processes that underlie etiologically diverse dystonias, and can suggest novel targets for therapeutic intervention that may be effective in a broad group of affected individuals.
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Affiliation(s)
- Valerie B Thompson
- Emory University School of Medicine, Department of Pharmacology, Woodruff Memorial Research Building, Suite 6000, 101 Woodruff Circle, Atlanta, GA 30322, USA
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76
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Lepage JF, Clouchoux C, Lassonde M, Evans AC, Deal CL, Théoret H. Abnormal motor cortex excitability is associated with reduced cortical thickness in X monosomy. Hum Brain Mapp 2011; 34:936-44. [PMID: 22102524 DOI: 10.1002/hbm.21481] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Revised: 07/27/2011] [Accepted: 09/09/2011] [Indexed: 11/05/2022] Open
Abstract
Turner syndrome (TS) is a noninherited genetic disorder caused by the absence of one or part of one X chromosome. It is characterized by physical and cognitive phenotypes that include motor deficits that may be related to neuroanatomical abnormalities of sensorimotor pathways. Here, we used transcranial magnetic stimulation (TMS) and cortical thickness analysis to assess motor cortex excitability and cortical morphology in 17 individuals with TS (45, X) and 17 healthy controls. Exploratory analysis was performed to detect the effect of parental origin of the X chromosome (X(mat), X(pat)) on both measures. Results showed that long-interval intracortical inhibition was reduced and motor threshold (MT) was increased in TS relative to controls. Areas of reduced thickness were observed in the precentral gyrus of individuals with TS that correlated with MT. A significant difference between X(mat) (n = 11) and X(pat) (n = 6) individuals was found on the measure of long-interval intracortical inhibition. These findings demonstrate the presence of converging anatomical and neurophysiological abnormalities of the motor system in X monosomy.
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77
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Corballis MC, Badzakova-Trajkov G, Häberling IS. Right hand, left brain: genetic and evolutionary bases of cerebral asymmetries for language and manual action. WILEY INTERDISCIPLINARY REVIEWS. COGNITIVE SCIENCE 2011; 3:1-17. [PMID: 26302469 DOI: 10.1002/wcs.158] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Most people are right-handed and left-cerebrally dominant for language. This pattern of asymmetry, as well as departures from it, have been reasonably accommodated in terms of a postulated gene with two alleles, one disposing to this common pattern and the other leaving the direction of handedness and language asymmetry to chance. There are some leads as to the location of the gene or genes concerned, but no clear resolution; one possibility is that the chance factor is achieved by epigenetic cancelling of the lateralizing gene rather than through a chance allele. Neurological evidence suggests that the neural basis of manual praxis, including pantomime and tool use, is more closely associated with cerebral asymmetry for language than with handedness, and is homologous with the so-called "mirror system" in the primate brain, which is specialized for manual grasping. The evidence reviewed supports the theory that language itself evolved within the praxic system, and became lateralized in humans, and perhaps to a lesser extent in our common ancestry with the great apes. WIREs Cogn Sci 2012, 3:1-17. doi: 10.1002/wcs.158 For further resources related to this article, please visit the WIREs website.
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78
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Niskanen E, Könönen M, Määttä S, Hallikainen M, Kivipelto M, Casarotto S, Massimini M, Vanninen R, Mervaala E, Karhu J, Soininen H. New insights into Alzheimer's disease progression: a combined TMS and structural MRI study. PLoS One 2011; 6:e26113. [PMID: 22022529 PMCID: PMC3192142 DOI: 10.1371/journal.pone.0026113] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Accepted: 09/19/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Combination of structural and functional data of the human brain can provide detailed information of neurodegenerative diseases and the influence of the disease on various local cortical areas. METHODOLOGY AND PRINCIPAL FINDINGS To examine the relationship between structure and function of the brain the cortical thickness based on structural magnetic resonance images and motor cortex excitability assessed with transcranial magnetic stimulation were correlated in Alzheimer's disease (AD) and mild cognitive impairment (MCI) patients as well as in age-matched healthy controls. Motor cortex excitability correlated negatively with cortical thickness on the sensorimotor cortex, the precuneus and the cuneus but the strength of the correlation varied between the study groups. On the sensorimotor cortex the correlation was significant only in MCI subjects. On the precuneus and cuneus the correlation was significant both in AD and MCI subjects. In healthy controls the motor cortex excitability did not correlate with the cortical thickness. CONCLUSIONS In healthy subjects the motor cortex excitability is not dependent on the cortical thickness, whereas in neurodegenerative diseases the cortical thinning is related to weaker cortical excitability, especially on the precuneus and cuneus. However, in AD subjects there seems to be a protective mechanism of hyperexcitability on the sensorimotor cortex counteracting the prominent loss of cortical volume since the motor cortex excitability did not correlate with the cortical thickness. Such protective mechanism was not found on the precuneus or cuneus nor in the MCI subjects. Therefore, our results indicate that the progression of the disease proceeds with different dynamics in the structure and function of neuronal circuits from normal conditions via MCI to AD.
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Affiliation(s)
- Eini Niskanen
- Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
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79
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May A. Experience-dependent structural plasticity in the adult human brain. Trends Cogn Sci 2011; 15:475-82. [PMID: 21906988 DOI: 10.1016/j.tics.2011.08.002] [Citation(s) in RCA: 300] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Revised: 08/12/2011] [Accepted: 08/15/2011] [Indexed: 01/15/2023]
Abstract
Contrary to assumptions that changes in brain networks are possible only during crucial periods of development, research in the past decade has supported the idea of a permanently plastic brain. Novel experience, altered afferent input due to environmental changes and learning new skills are now recognized as modulators of brain function and underlying neuroanatomic circuitry. Given findings in experiments with animals and the recent discovery of increases in gray and white matter in the adult human brain as a result of learning, the old concept of cognitive reserve, that is the ability to reinforce brain volume in crucial areas and thus provide a greater threshold for age-dependent deficits, has been reinforced. The challenge we face is to unravel the exact nature of the dynamic structural alterations and, ultimately, to be able to use this knowledge for disease management. Understanding normative changes in brain structure that occur as a result of environmental changes and demands is pivotal to understanding the characteristic ability of the brain to adapt.
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Affiliation(s)
- Arne May
- Department of Systems Neuroscience, University Clinic Hamburg Eppendorf (UKE), D-20246 Hamburg, Germany.
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80
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Simonyan K, Ludlow CL. Abnormal structure-function relationship in spasmodic dysphonia. Cereb Cortex 2011; 22:417-25. [PMID: 21666131 DOI: 10.1093/cercor/bhr120] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Spasmodic dysphonia (SD) is a primary focal dystonia characterized by involuntary spasms in the laryngeal muscles during speech production. Although recent studies have found abnormal brain function and white matter organization in SD, the extent of gray matter alterations, their structure-function relationships, and correlations with symptoms remain unknown. We compared gray matter volume (GMV) and cortical thickness (CT) in 40 SD patients and 40 controls using voxel-based morphometry and cortical distance estimates. These measures were examined for relationships with blood oxygen level-dependent signal change during symptomatic syllable production in 15 of the same patients. SD patients had increased GMV, CT, and brain activation in key structures of the speech control system, including the laryngeal sensorimotor cortex, inferior frontal gyrus (IFG), superior/middle temporal and supramarginal gyri, and in a structure commonly abnormal in other primary dystonias, the cerebellum. Among these regions, GMV, CT and activation of the IFG and cerebellum showed positive relationships with SD severity, while CT of the IFG correlated with SD duration. The left anterior insula was the only region with decreased CT, which also correlated with SD symptom severity. These findings provide evidence for coupling between structural and functional abnormalities at different levels within the speech production system in SD.
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Affiliation(s)
- Kristina Simonyan
- Department of Neurology, Mount Sinai School of Medicine, New York, NY 10029, USA.
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81
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Gray matter alterations in visual cortex of patients with loss of central vision due to hereditary retinal dystrophies. Neuroimage 2011; 56:1556-65. [DOI: 10.1016/j.neuroimage.2011.02.055] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Revised: 01/28/2011] [Accepted: 02/17/2011] [Indexed: 11/21/2022] Open
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Abstract
In the human brain, homologous regions of the primary motor cortices (M1s) are connected through transcallosal fibers. Interhemispheric communication between the two M1s plays a major role in the control of unimanual hand movements, and the strength of this connection seems to be dependent on arm activity. For instance, a lesion in the M1 can induce an increase in the excitability of the intact M1 and an abnormal high inhibitory influence onto the damaged M1. This can be attributable to either the disuse of the affected limb or the overuse of the unaffected one. Here, to directly investigate cortical modifications induced by an abnormal asymmetric use of the two limbs, we studied both the excitability of the two M1s and transcallosal interaction between them in healthy subjects whose right hand was immobilized for 10 h. The left "not-immobilized" arm was completely free to move in one group of participants (G1) and limited in the other one (G2). We found that the non-use reduced the excitability of the left M1 and decreased the inhibitory influence onto the right hemisphere in the two groups. However, an increase in the excitability of right M1 and a deeper inhibitory interaction onto the left hemisphere were evident only in G1. Thus, modifications in the right M1 were not directly produced by the non-use but would depend on the overuse of the "not-immobilized" arm. Our findings suggest that the balance between the two M1s is strongly use dependent.
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83
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Lou AR, Madsen KH, Paulson OB, Julian HO, Prause JU, Siebner HR, Kjaer TW. Monocular Visual Deprivation Suppresses Excitability in Adult Human Visual Cortex. Cereb Cortex 2011; 21:2876-82. [DOI: 10.1093/cercor/bhr082] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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84
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Neychev VK, Gross RE, Lehéricy S, Hess EJ, Jinnah HA. The functional neuroanatomy of dystonia. Neurobiol Dis 2011; 42:185-201. [PMID: 21303695 DOI: 10.1016/j.nbd.2011.01.026] [Citation(s) in RCA: 320] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Revised: 01/08/2011] [Accepted: 01/28/2011] [Indexed: 10/18/2022] Open
Abstract
Dystonia is a neurological disorder characterized by involuntary twisting movements and postures. There are many different clinical manifestations, and many different causes. The neuroanatomical substrates for dystonia are only partly understood. Although the traditional view localizes dystonia to basal ganglia circuits, there is increasing recognition that this view is inadequate for accommodating a substantial portion of available clinical and experimental evidence. A model in which several brain regions play a role in a network better accommodates the evidence. This network model accommodates neuropathological and neuroimaging evidence that dystonia may be associated with abnormalities in multiple different brain regions. It also accommodates animal studies showing that dystonic movements arise with manipulations of different brain regions. It is consistent with neurophysiological evidence suggesting defects in neural inhibitory processes, sensorimotor integration, and maladaptive plasticity. Finally, it may explain neurosurgical experience showing that targeting the basal ganglia is effective only for certain subpopulations of dystonia. Most importantly, the network model provides many new and testable hypotheses with direct relevance for new treatment strategies that go beyond the basal ganglia. This article is part of a Special Issue entitled "Advances in dystonia".
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