WorldWideScience

Sample records for cortex bilateral motor

  1. Altered structural and functional connectivity between the bilateral primary motor cortex in unilateral subcortical stroke

    Science.gov (United States)

    Zhang, Yong; Li, Kuang-Shi; Ning, Yan-Zhe; Fu, Cai-Hong; Liu, Hong-Wei; Han, Xiao; Cui, Fang-Yuan; Ren, Yi; Zou, Yi-Huai

    2016-01-01

    Abstract A large number of functional imaging studies have focused on the understanding of motor-related neural activities after ischemic stroke. However, the knowledge is still limited in the structural and functional changes of the interhemispheric connections of the bilateral primary motor cortices (M1s) and their potential influence on motor function recovery following stroke. Twenty-four stroke patients with right hemispheric subcortical infarcts and 25 control subjects were recruited to undergo multimodal magnetic resonance imaging examinations. Structural impairments between the bilateral M1s were measured by fractional anisotropy. Functional changes of the bilateral M1s were assessed via M1-M1 resting-state functional connectivity. Task-evoked activation analysis was applied to identify the roles of the bilateral hemispheres in motor function recovery. Compared with control subjects, unilateral subcortical stroke patients revealed significantly decreased fractional anisotropy and functional connectivity between the bilateral M1s. Stroke patients also revealed higher activations in multiple brain regions in both hemispheres and that more regions were located in the contralesional hemisphere. This study increased our understanding of the structural and functional alterations between the bilateral M1s that occur in unilateral subcortical stroke and provided further evidence for the compensatory role played by the contralesional hemisphere for these alterations during motor function recovery. PMID:27495109

  2. Impairments of motor-cortex responses to unilateral and bilateral direct current stimulation in schizophrenia

    Directory of Open Access Journals (Sweden)

    Alkomiet eHasan

    2013-10-01

    Full Text Available Transcranial direct current stimulation (tDCS is a non-invasive stimulation technique that can be applied to modulate cortical activity through induction of cortical plasticity. Since various neuropsychiatric disorders are characterised by fluctuations in cortical activity levels (e.g. schizophrenia, tDCS is increasingly investigated as a treatment tool. Several studies have shown that the induction of cortical plasticity following classical, unilateral tDCS is reduced or impaired in the stimulated and non-stimulated primary motor cortices (M1 of schizophrenia patients. Moreover, an alternative, bilateral tDCS setup has recently been shown to modulate cortical plasticity in both hemispheres in healthy subjects, highlighting another potential treatment approach. Here we present the first study comparing the efficacy of unilateral tDCS (cathode left M1, anode right supraorbital with simultaneous bilateral tDCS (cathode left M1, anode right M1 in schizophrenia patients. tDCS-induced cortical plasticity was monitored by investigating motor-evoked potentials induced by single-pulse transcranial magnetic stimulation applied to both hemispheres. Healthy subjects showed a reduction of left M1 excitability following unilateral tDCS on the stimulated left hemisphere and an increase in right M1 excitability following bilateral tDCS. In schizophrenia, no plasticity was induced following both stimulation paradigms. The pattern of these results indicates a complex interplay between plasticity and connectivity that is impaired in schizophrenia patients. Further studies are needed to clarify the biological underpinnings and clinical impact of these findings.

  3. Impairments of motor-cortex responses to unilateral and bilateral direct current stimulation in schizophrenia.

    Science.gov (United States)

    Hasan, Alkomiet; Bergener, Theresa; Nitsche, Michael A; Strube, Wolfgang; Bunse, Tilmann; Falkai, Peter; Wobrock, Thomas

    2013-01-01

    Transcranial direct current stimulation (tDCS) is a non-invasive stimulation technique that can be applied to modulate cortical activity through induction of cortical plasticity. Since various neuropsychiatric disorders are characterized by fluctuations in cortical activity levels (e.g., schizophrenia), tDCS is increasingly investigated as a treatment tool. Several studies have shown that the induction of cortical plasticity following classical, unilateral tDCS is reduced or impaired in the stimulated and non-stimulated primary motor cortices (M1) of patients with schizophrenia. Moreover, an alternative, bilateral tDCS setup has recently been shown to modulate cortical plasticity in both hemispheres in healthy subjects, highlighting another potential treatment approach. Here we present the first study comparing the efficacy of unilateral tDCS (cathode left M1, anode right supraorbital) with simultaneous bilateral tDCS (cathode left M1, anode right M1) in patients with schizophrenia. tDCS-induced cortical plasticity was monitored by investigating motor-evoked potentials induced by single-pulse transcranial magnetic stimulation applied to both hemispheres. Healthy subjects showed a reduction of left M1 excitability following unilateral tDCS on the stimulated left hemisphere and an increase in right M1 excitability following bilateral tDCS. In schizophrenia, no plasticity was induced following both stimulation paradigms. The pattern of these results indicates a complex interplay between plasticity and connectivity that is impaired in patients with schizophrenia. Further studies are needed to clarify the biological underpinnings and clinical impact of these findings.

  4. A comparison between uni- and bilateral tDCS effects on functional connectivity of the human motor cortex

    Directory of Open Access Journals (Sweden)

    Bernhard eSehm

    2013-05-01

    Full Text Available tDCS over the primary motor cortex (M1 has been shown to induce changes in motor performance and learning. Recent studies indicate that tDCS is capable of modulating widespread neural network properties within the brain. However the temporal evolution of online- and after- effects of tDCS on functional connectivity within and across the stimulated motor cortices (M1 still remain elusive. In the present study, two different tDCS setups were investigated: (i unilateral M1 tDCS (anode over right M1, cathode over the contralateral supraorbital region and (ii bilateral M1 tDCS (anode over right M1, cathode over left M1. In a randomized single-blinded crossover design, 12 healthy subjects underwent resting-state functional magnetic resonance imaging at rest (rs-fMRI before, during and after 20 min of either bi-, unilateral or sham M1 tDCS. Seed-based functional connectivity analysis (FC was used to investigate tDCS-induced changes across and within M1. We found that bilateral M1 tDCS induced (a a decrease in interhemispheric FC during stimulation and (b an increase in intracortical FC within right M1 after termination of the intervention. While unilateral M1 tDCS also resulted in similar effects during stimulation, no such changes could be observed after termination of tDCS. Our results provide evidence that depending on the electrode montage, tDCS acts upon a modulation of either intracortical and/or interhemispheric processing of M1.

  5. Task-concurrent anodal tDCS modulates bilateral plasticity in the human suprahyoid motor cortex

    Directory of Open Access Journals (Sweden)

    Shaofeng eZhao

    2015-06-01

    Full Text Available Transcranial direct current stimulation (tDCS is a non-invasive method to modulate cortical excitability in humans. Here, we examined the effects of anodal tDCS on suprahyoid motor evoked potentials (MEP when applied over the hemisphere with stronger and weaker suprahyoid/submental projections, respectively, while study participants performed a swallowing task. 30 healthy volunteers were invited to two experimental sessions and randomly assigned to one of two different groups. While in the first group stimulation was targeted over the hemisphere with stronger suprahyoid projections, the second group received stimulation over the weaker suprahyoid projections. tDCS was applied either as anodal or sham stimulation in a random cross-over design. Suprahyoid MEPs were assessed immediately before intervention, as well as 5, 30, 60, and 90 min after discontinuation of stimulation from both the stimulated and non-stimulated contralateral hemisphere. We found that anodal tDCS (a-tDCS had long-lasting effects on suprahyoid MEPs on the stimulated side in both groups (tDCS targeting the stronger projections: F(1,14 = 96.2, p < 0.001; tDCS targeting the weaker projections: F(1,14 = 37.45, p < 0.001. While MEPs did not increase when elicited from the non-targeted hemisphere after stimulation of the stronger projections (F(1,14 = 0.69, p = 0.42, we found increased MEPs elicited from the non-targeted hemisphere after stimulating the weaker projections (at time points 30 to 90 min (F(1,14 = 18.26, p = 0.001. We conclude that anodal tDCS has differential effects on suprahyoid MEPs elicited from the targeted and non-targeted hemisphere depending on the site of stimulation. This finding may be important for the application of a-tDCS in patients with dysphagia, for example after stroke.

  6. Sensing with the Motor Cortex

    OpenAIRE

    Hatsopoulos, Nicholas G.; Suminski, Aaron J.

    2011-01-01

    The primary motor cortex is a critical node in the network of brain regions responsible for voluntary motor behavior. It has been less appreciated, however, that the motor cortex exhibits sensory responses in a variety of modalities including vision and somatosensation. We review current work that emphasizes the heterogeneity in sensori-motor responses in the motor cortex and focus on its implications for cortical control of movement as well as for brain-machine interface development.

  7. Altered structural and functional connectivity between the bilateral primary motor cortex in unilateral subcortical stroke: A multimodal magnetic resonance imaging study.

    Science.gov (United States)

    Zhang, Yong; Li, Kuang-Shi; Ning, Yan-Zhe; Fu, Cai-Hong; Liu, Hong-Wei; Han, Xiao; Cui, Fang-Yuan; Ren, Yi; Zou, Yi-Huai

    2016-08-01

    A large number of functional imaging studies have focused on the understanding of motor-related neural activities after ischemic stroke. However, the knowledge is still limited in the structural and functional changes of the interhemispheric connections of the bilateral primary motor cortices (M1s) and their potential influence on motor function recovery following stroke.Twenty-four stroke patients with right hemispheric subcortical infarcts and 25 control subjects were recruited to undergo multimodal magnetic resonance imaging examinations. Structural impairments between the bilateral M1s were measured by fractional anisotropy. Functional changes of the bilateral M1s were assessed via M1-M1 resting-state functional connectivity. Task-evoked activation analysis was applied to identify the roles of the bilateral hemispheres in motor function recovery. Compared with control subjects, unilateral subcortical stroke patients revealed significantly decreased fractional anisotropy and functional connectivity between the bilateral M1s. Stroke patients also revealed higher activations in multiple brain regions in both hemispheres and that more regions were located in the contralesional hemisphere.This study increased our understanding of the structural and functional alterations between the bilateral M1s that occur in unilateral subcortical stroke and provided further evidence for the compensatory role played by the contralesional hemisphere for these alterations during motor function recovery.

  8. Motor cortex neuroplasticity following brachial plexus transfer

    Directory of Open Access Journals (Sweden)

    Stefan eDimou

    2013-08-01

    Full Text Available In the past decade, research has demonstrated that cortical plasticity, once thought only to exist in the early stages of life, does indeed continue on into adulthood. Brain plasticity is now acknowledged as a core principle of brain function and describes the ability of the central nervous system to adapt and modify its structural organization and function as an adaptive response to functional demand. In this clinical case study we describe how we used neuroimaging techniques to observe the functional topographical expansion of a patch of cortex along the sensorimotor cortex of a 27 year-old woman following brachial plexus transfer surgery to re-innervate her left arm. We found bilateral activations present in the thalamus, caudate, insula as well as across the sensorimotor cortex during an elbow flex motor task. In contrast we found less activity in the sensorimotor cortex for a finger tap motor task in addition to activations lateralised to the left inferior frontal gyrus and thalamus and bilaterally for the insula. From a pain perspective the patient who had experienced extensive phantom limb pain before surgery found these sensations were markedly reduced following transfer of the right brachial plexus to the intact left arm. Within the context of this clinical case the results suggest that functional improvements in limb mobility are associated with increased activation in the sensorimotor cortex as well as reduced phantom limb pain.

  9. Effects of unilateral and bilateral training in a reaching task on dendritic branching of neurons in the rat motor-sensory forelimb cortex.

    Science.gov (United States)

    Greenough, W T; Larson, J R; Withers, G S

    1985-09-01

    Effects of motor training on a neocortical nerve cell population involved in performance of the motor task were assessed by measuring Layer V pyramidal neuron apical dendritic branching in motor-sensory forelimb cortex of rats trained to reach into a tube for food. Rats were trained to reach with the forepaw they preferred to use (group PRAC), the nonpreferred forepaw (REV), both forepaws (ALT), or neither forepaw (CONT). Across groups, hemispheres opposite trained forepaws had larger apical dendritic fields, in terms of total dendritic length, number of oblique branches from the apical shaft, and length of terminal branches. Similar, although somewhat less consistent, effects were seen when results were analyzed for between- (CONT vs ALT) and within-subject comparisons (trained vs nontrained hemispheres of REV and PRAC). This finding is compatible with the hypothesis that altered dendritic patterns, with associated synapses, are involved in storage of information from the training experience. The within-subject effects mitigate suggestions that these differences arise from generally acting hormonal or metabolic consequences of the training experience, although the possibility that these effects result from neural activity per se and are unrelated to information storage cannot be excluded.

  10. Bilateral low frequency rTMS of the primary motor cortex may not be a suitable treatment for levodopa-induced dyskinesias in late stage Parkinson's disease

    NARCIS (Netherlands)

    Flamez, Anja; Cordenier, Ann; De Raedt, Sylvie; Michiels, Veronique; Smetcoren, Sara; Van Merhaegen-Wieleman, Annick; Parys, Eva; De Keyser, Jacques; Baeken, Chris

    2016-01-01

    Background: In late stage Parkinson patients there is an unmet need for new treatments to adequately control motor complications, especially dyskinesias. In several preliminary studies, it has been suggested that applying unilateral low-frequency repetitive transcranial magnetic stimulation (LF rTMS

  11. Seeing fearful body language rapidly freezes the observer's motor cortex.

    Science.gov (United States)

    Borgomaneri, Sara; Vitale, Francesca; Gazzola, Valeria; Avenanti, Alessio

    2015-04-01

    Fearful body language is a salient signal alerting the observer to the presence of a potential threat in the surrounding environment. Although detecting potential threats may trigger an immediate reduction of motor output in animals (i.e., freezing behavior), it is unclear at what point in time similar reductions occur in the human motor cortex and whether they originate from excitatory or inhibitory processes. Using single-pulse and paired-pulse transcranial magnetic stimulation (TMS), here we tested the hypothesis that the observer's motor cortex implements extremely fast suppression of motor readiness when seeing emotional bodies - and fearful body expressions in particular. Participants observed pictures of body postures and categorized them as happy, fearful or neutral while receiving TMS over the right or left motor cortex at 100-125 msec after picture onset. In three different sessions, we assessed corticospinal excitability, short intracortical inhibition (SICI) and intracortical facilitation (ICF). Independently of the stimulated hemisphere and the time of the stimulation, watching fearful bodies suppressed ICF relative to happy and neutral body expressions. Moreover, happy expressions reduced ICF relative to neutral actions. No changes in corticospinal excitability or SICI were found during the task. These findings show extremely rapid bilateral modulation of the motor cortices when seeing emotional bodies, with stronger suppression of motor readiness when seeing fearful bodies. Our results provide neurophysiological support for the evolutionary notions that emotion perception is inherently linked to action systems and that fear-related cues induce an urgent mobilization of motor reactions.

  12. Coding of movements in the motor cortex.

    Science.gov (United States)

    Georgopoulos, Apostolos P; Carpenter, Adam F

    2015-08-01

    The issue of coding of movement in the motor cortex has recently acquired special significance due to its fundamental importance in neuroprosthetic applications. The challenge of controlling a prosthetic arm by processed motor cortical activity has opened a new era of research in applied medicine but has also provided an 'acid test' for hypotheses regarding coding of movement in the motor cortex. The successful decoding of movement information from the activity of motor cortical cells using their directional tuning and population coding has propelled successful neuroprosthetic applications and, at the same time, asserted the utility of those early discoveries, dating back to the early 1980s.

  13. Where does TMS Stimulate the Motor Cortex?

    DEFF Research Database (Denmark)

    Bungert, Andreas; Antunes, André; Espenhahn, Svenja;

    2016-01-01

    Much of our knowledge on the physiological mechanisms of transcranial magnetic stimulation (TMS) stems from studies which targeted the human motor cortex. However, it is still unclear which part of the motor cortex is predominantly affected by TMS. Considering that the motor cortex consists...... of functionally and histologically distinct subareas, this also renders the hypotheses on the physiological TMS effects uncertain. We use the finite element method (FEM) and magnetic resonance image-based individual head models to get realistic estimates of the electric field induced by TMS. The field changes...... in different subparts of the motor cortex are compared with electrophysiological threshold changes of 2 hand muscles when systematically varying the coil orientation in measurements. We demonstrate that TMS stimulates the region around the gyral crown and that the maximal electric field strength in this region...

  14. The lateralization of motor cortex activation to action words

    Directory of Open Access Journals (Sweden)

    Olaf eHauk

    2011-11-01

    Full Text Available What determines the laterality of activation in motor cortex for words whose meaning is related to bodily actions? It has been suggested that the neuronal representation of the meaning of action-words is shaped by individual experience. However, core language functions are left-lateralized in the majority of both right- and left-handers. It is still an open question to what degree connections between left-hemispheric core language areas and right-hemispheric motor areas can play a role in semantics. We investigated laterality of brain activation using fMRI in right- and left-handed participants in response to visually presented hand-related action-words, namely uni- and bi-manual actions (such as "throw" and "clap". These stimulus groups were matched with respect to general (hand-action-relatedness, but differed with respect to whether they are usually performed with the dominant hand or both hands. We may expect generally more left-hemispheric motor-cortex activation for hand-related words in both handedness groups, with possibly more bilateral activation for bimanual words as well as left-handers. In our study, both participant groups activated motor cortex bilaterally for bi-manual words. Interestingly, both groups also showed a left-lateralized activation pattern to uni-manual words. We argue that this reflects the effect of left-hemispheric language dominance on the formation of semantic brain circuits on the basis of Hebbian correlation learning.

  15. Motor Cortex Stimulation in Parkinson's Disease

    OpenAIRE

    Marisa De Rose; Giusy Guzzi; Domenico Bosco; Mary Romano; Serena Marianna Lavano; Massimiliano Plastino; Giorgio Volpentesta; Rosa Marotta; Angelo Lavano

    2012-01-01

    Motor Cortex Stimulation (MCS) is less efficacious than Deep Brain Stimulation (DBS) in Parkinson's disease. However, it might be proposed to patients excluded from DBS or unresponsive to DBS. Ten patients with advanced PD underwent unilateral MCS contralaterally to the worst clinical side. A plate electrode was positioned over the motor cortex in the epidural space through single burr hole after identification of the area with neuronavigation and neurophysiological tests. Clinical assessment...

  16. Dr. Otto Soltmann (1876) on development of the motor cortex and recovery after its removal in infancy.

    Science.gov (United States)

    Finger, S; Beyer, T; Koehler, P J

    2000-09-15

    In 1870, Fritsch and Hitzig demonstrated that dogs have a motor cortex. In a chapter published 6 years later, Otto Soltmann studied the functional development of the motor cortex, which he believed functioned in willed movement. He was the first to show that the dog's motor cortex becomes electrically excitable at about 10 days of age, with the contralateral forepaw area appearing first. He also studied the effects of ablating the cortical motor regions unilaterally and bilaterally, and encountered a remarkable degree of sparing of function in his animals operated on as newborns, but not in older-operated dogs. Soltmann turned to the theory of functional take-over (vicariation) to account for the absence of deficits in his young animals. He was especially intrigued by the fact that electrical stimulation of a healthy motor cortex could produce bilateral matched movements, but only in dogs that sustained opposite motor cortex lesions very early in life.

  17. Does intrinsic motivation enhance motor cortex excitability?

    Science.gov (United States)

    Radel, Rémi; Pjevac, Dusan; Davranche, Karen; d'Arripe-Longueville, Fabienne; Colson, Serge S; Lapole, Thomas; Gruet, Mathieu

    2016-11-01

    Intrinsic motivation (IM) is often viewed as a spontaneous tendency for action. Recent behavioral and neuroimaging evidence indicate that IM, in comparison to extrinsic motivation (EM), solicits the motor system. Accordingly, we tested whether IM leads to greater excitability of the motor cortex than EM. To test this hypothesis, we used two different tasks to induce the motivational orientation using either words representing each motivational orientation or pictures previously linked to each motivational orientation through associative learning. Single-pulse transcranial magnetic stimulation over the motor cortex was applied when viewing the stimuli. Electromyographic activity was recorded on the contracted first dorsal interosseous muscle. Two indexes of corticospinal excitability (the amplitude of motor-evoked potential and the length of cortical silent period) were obtained through unbiased automatic detection and analyzed using a mixed model that provided both statistical power and a high level of control over all important individual, task, and stimuli characteristics. Across the two tasks and the two indices of corticospinal excitability, the exposure to IM-related stimuli did not lead to a greater corticospinal excitability than EM-related stimuli or than stimuli with no motivational valence (ps > .20). While these results tend to dismiss the advantage of IM at activating the motor cortex, we suggest alternative hypotheses to explain this lack of effect, which deserves further research. © 2016 Society for Psychophysiological Research.

  18. Sensory-motor transformations for speech occur bilaterally.

    Science.gov (United States)

    Cogan, Gregory B; Thesen, Thomas; Carlson, Chad; Doyle, Werner; Devinsky, Orrin; Pesaran, Bijan

    2014-03-01

    Historically, the study of speech processing has emphasized a strong link between auditory perceptual input and motor production output. A kind of 'parity' is essential, as both perception- and production-based representations must form a unified interface to facilitate access to higher-order language processes such as syntax and semantics, believed to be computed in the dominant, typically left hemisphere. Although various theories have been proposed to unite perception and production, the underlying neural mechanisms are unclear. Early models of speech and language processing proposed that perceptual processing occurred in the left posterior superior temporal gyrus (Wernicke's area) and motor production processes occurred in the left inferior frontal gyrus (Broca's area). Sensory activity was proposed to link to production activity through connecting fibre tracts, forming the left lateralized speech sensory-motor system. Although recent evidence indicates that speech perception occurs bilaterally, prevailing models maintain that the speech sensory-motor system is left lateralized and facilitates the transformation from sensory-based auditory representations to motor-based production representations. However, evidence for the lateralized computation of sensory-motor speech transformations is indirect and primarily comes from stroke patients that have speech repetition deficits (conduction aphasia) and studies using covert speech and haemodynamic functional imaging. Whether the speech sensory-motor system is lateralized, like higher-order language processes, or bilateral, like speech perception, is controversial. Here we use direct neural recordings in subjects performing sensory-motor tasks involving overt speech production to show that sensory-motor transformations occur bilaterally. We demonstrate that electrodes over bilateral inferior frontal, inferior parietal, superior temporal, premotor and somatosensory cortices exhibit robust sensory-motor neural

  19. Effects of aging on motor cortex excitability.

    Science.gov (United States)

    Oliviero, A; Profice, P; Tonali, P A; Pilato, F; Saturno, E; Dileone, M; Ranieri, F; Di Lazzaro, V

    2006-05-01

    To determine whether aging is associated with changes in excitability of the cerebral cortex, we evaluated the excitability of the motor cortex with transcranial magnetic stimulation (TMS). We compared TMS related measures obtained in a group of young people with those of a group of old people. Motor evoked potential (MEP) amplitude was significantly smaller in older than in younger controls (1.3+/-0.8 mV versus 2.7+/-1.1 mV; p<0.0071). Mean cortical silent period (CSP) duration was shorter in older than in younger controls (87+/-29 ms versus 147+/-39 ms; p<0.0071). SP duration/MEP amplitude ratios were similar in both groups. Our results are consistent with an impaired efficiency of some intracortical circuits in old age.

  20. Primary study on hand motor cortex mapping by using navigated transcranial magnetic stimulation

    Directory of Open Access Journals (Sweden)

    Shuai LI

    2016-08-01

    Full Text Available Objective To investigate the feasibility and safety of using navigated transcranial magnetic stimulation (nTMS to map hand motor cortex and further analyze its clinical application.  Methods The first dorsal interosseous (FDI was selected as target muscle. The location and area of bilateral FDI were mapped by using nTMS in 10 healthy right-handed volunteers. In order to identify the accuracy of nTMS, all individual MRI volumes and the coordinates of hotspots were normalized to Montreal Neurological Institute (MNI space using SPM8. Positive sites and motor-evoked potential (MEP were recorded. The areas of hand motor representations were calculated and compared between bilateral cerebral hemispheres.  Results nTMS was capable of identifying hand motor cortex area in both hemispheres in all cases. It took 45 to 60 minutes to finish the whole nTMS procedures of each side of hand motor area. The motor cortex was found at the Ω area of bilateral precentral gyri. The right hand motor representation area was significantly larger than that of left area [(6.22 ± 0.76 cm2 vs (4.30 ± 0.40 cm2; t = 7.078, P = 0.000]. Four cases presented sleepiness, but no side effect such as headache or epilepsy was found.  Conclusions nTMS is a reliable and safe technique to map hand motor cortex. It can be a very useful supplementary tool for preoperative motor cortex mapping and study on motor functional remodeling. DOI: 10.3969/j.issn.1672-6731.2016.08.011

  1. Finger somatotopy in human motor cortex.

    Science.gov (United States)

    Beisteiner, R; Windischberger, C; Lanzenberger, R; Edward, V; Cunnington, R; Erdler, M; Gartus, A; Streibl, B; Moser, E; Deecke, L

    2001-06-01

    Although qualitative reports about somatotopic representation of fingers in the human motor cortex exist, up to now no study could provide clear statistical evidence. The goal of the present study was to reinvestigate finger motor somatotopy by means of a thorough investigation of standardized movements of the index and little finger of the right hand. Using high resolution fMRI at 3 Tesla, blood oxygenation level-dependent (BOLD) responses in a group of 26 subjects were repeatedly measured to achieve reliable statistical results. The center of mass of all activated voxels within the primary motor cortex was calculated for each finger and each run. Results of all runs were averaged to yield an individual index and little finger representation for each subject. The mean center of mass localizations for all subjects were then submitted to a paired t test. Results show a highly significant though small scale somatotopy of fingerspecific activation patterns in the order indicated by Penfields motor homunculus. In addition, considerable overlap of finger specific BOLD responses was found. Comparing various methods of analysis, the mean center of mass distance for the two fingers was 2--3 mm with overlapping voxels included and 4--5 mm with overlapping voxels excluded. Our data may be best understood in the context of the work of Schieber (1999) who recently described overlapping somatotopic gradients in lesion studies with humans. Copyright 2001 Academic Press.

  2. Anodic or cathodic motor cortex stimulation for pain?

    NARCIS (Netherlands)

    Holsheimer, J.; Manola, L.

    2006-01-01

    Objective. In motor cortex stimulation (MCS) for central and trigeminal pain Resume leads are placed epidurally over the motor and sensory cortex. Several bipolar combinations are used to identify the cortical target corresponding to the painful body segment. The cathode giving the largest motor r

  3. Bilateral projections from rat MI whisker cortex to the neostriatum, thalamus, and claustrum: forebrain circuits for modulating whisking behavior.

    Science.gov (United States)

    Alloway, Kevin D; Smith, Jared B; Beauchemin, Kyle J; Olson, Michelle L

    2009-08-10

    In rats, whisking behavior is characterized by high-frequency synchronous movements and other stereotyped patterns of bilateral coordination that are rarely seen in the bilateral movements of the limbs. This suggests that the motor systems controlling whisker and limb movements must have qualitative or quantitative differences in their interhemispheric connections. To test this hypothesis, anterograde tracing methods were used to characterize the bilateral distribution of projections from the whisker and forepaw regions in the primary motor (MI) cortex. Unilateral tracer injections in the MI whisker or forepaw regions revealed robust projections to the corresponding MI cortical area in the contralateral hemisphere. Both MI regions project bilaterally to the neostriatum, but the corticostriatal projections from the whisker region are denser and more evenly distributed across both hemispheres than those from the MI forepaw region. The MI whisker region projects bilaterally to several nuclei in the thalamus, whereas the MI forepaw region projects almost exclusively to the ipsilateral thalamus. The MI whisker region sends dense projections to the contralateral claustrum, but those to the ipsilateral claustrum are less numerous. By contrast, the MI forepaw region sends few projections to the claustrum of either hemisphere. Bilateral deposits of different tracers in MI revealed overlapping projections to the neostriatum, thalamus, and claustrum when the whisker regions were injected, but not when the forepaw regions were injected. These results suggest that the bilateral coordination of the whiskers depends, in part, on MI projections to the contralateral neostriatum, thalamus, and claustrum. Copyright 2009 Wiley-Liss, Inc.

  4. Motor cortex stimulation in Parkinson's disease.

    Science.gov (United States)

    De Rose, Marisa; Guzzi, Giusy; Bosco, Domenico; Romano, Mary; Lavano, Serena Marianna; Plastino, Massimiliano; Volpentesta, Giorgio; Marotta, Rosa; Lavano, Angelo

    2012-01-01

    Motor Cortex Stimulation (MCS) is less efficacious than Deep Brain Stimulation (DBS) in Parkinson's disease. However, it might be proposed to patients excluded from DBS or unresponsive to DBS. Ten patients with advanced PD underwent unilateral MCS contralaterally to the worst clinical side. A plate electrode was positioned over the motor cortex in the epidural space through single burr hole after identification of the area with neuronavigation and neurophysiological tests. Clinical assessment was performed by total UPDRS, UPDRS III total, UPDRS III-items 27-31, UPDRS IV, and UPDRS II before implantation in off-medication and on-medication states and after surgery at 1, 3, 6, 12, 18, 24, and 36 months in on-medication/on-stimulation and off-medication/on-stimulation states. We assessed changes of quality of life, throughout the Parkinson's disease quality of life scale (PDQoL-39), and the dose of anti-Parkinson's disease medications, throughout the Ldopa equivalent daily dose (LEDD). During off-medication state, we observed moderate and transitory reduction of total UPDRS and UPDRS total scores and significant and long-lasting improvement in UPDRS III items 27-31 score for axial symptoms. There was marked reduction of UPDRS IV score and LEDD. PDQL-39 improvement was also significant. No important complications and adverse events occurred.

  5. Motor Cortex Stimulation in Parkinson's Disease

    Directory of Open Access Journals (Sweden)

    Marisa De Rose

    2012-01-01

    Full Text Available Motor Cortex Stimulation (MCS is less efficacious than Deep Brain Stimulation (DBS in Parkinson's disease. However, it might be proposed to patients excluded from DBS or unresponsive to DBS. Ten patients with advanced PD underwent unilateral MCS contralaterally to the worst clinical side. A plate electrode was positioned over the motor cortex in the epidural space through single burr hole after identification of the area with neuronavigation and neurophysiological tests. Clinical assessment was performed by total UPDRS, UPDRS III total, UPDRS III-items 27–31, UPDRS IV, and UPDRS II before implantation in off-medication and on-medication states and after surgery at 1, 3, 6, 12, 18, 24, and 36 months in on-medication/on-stimulation and off-medication/on-stimulation states. We assessed changes of quality of life, throughout the Parkinson's disease quality of life scale (PDQoL-39, and the dose of anti-Parkinson's disease medications, throughout the Ldopa equivalent daily dose (LEDD. During off-medication state, we observed moderate and transitory reduction of total UPDRS and UPDRS total scores and significant and long-lasting improvement in UPDRS III items 27–31 score for axial symptoms. There was marked reduction of UPDRS IV score and LEDD. PDQL-39 improvement was also significant. No important complications and adverse events occurred.

  6. Cerebellum to motor cortex paired associative stimulation induces bidirectional STDP-like plasticity in human motor cortex

    OpenAIRE

    Lu, Ming-Kuei; Tsai, Chon-Haw; Ziemann, Ulf

    2012-01-01

    The cerebellum is crucially important for motor control and adaptation. Recent non-invasive brain stimulation studies have indicated the possibility to alter the excitability of the cerebellum and its projections to the contralateral motor cortex, with behavioral consequences on motor control and adaptation. Here we sought to induce bidirectional spike-timing dependent plasticity (STDP)-like modifications of motor cortex (M1) excitability by application of paired associative stimulation (PAS)...

  7. Functional organization of motor cortex of adult macaque monkeys is altered by sensory loss in infancy.

    Science.gov (United States)

    Qi, Hui-Xin; Jain, Neeraj; Collins, Christine E; Lyon, David C; Kaas, Jon H

    2010-02-16

    When somatosensory cortex (S1) is deprived of some of its inputs after section of ascending afferents in the dorsal columns of the spinal cord, it reorganizes to overrepresent the surviving inputs. As somatosensory cortex provides guiding sensory information to motor cortex, such sensory loss and representational reorganization could affect the development of the motor map in primary motor cortex (M1), especially if the sensory loss occurs early in development. To address this possibility, the dorsal columns of the spinal cord were sectioned between cervical levels (C3-5) 3-12 days after birth in five macaque monkeys. After 3-5 years of maturation (young adults), we determined how movements were represented in M1 contralateral to the lesion by using microelectrodes to electrically stimulate sites in M1 to evoke movements. Although the details of the motor maps in these five monkeys varied, the forelimb motor maps were abnormal. The representations of digit movements were reduced and abnormally arranged. Current levels for evoking movements from the forelimb region of M1 were in the normal range, but the lowest mean stimulation thresholds were for wrist or elbow instead of digit movements. Incomplete lesions and bilateral lesions produced fewer abnormalities. The results suggest that the development of normal motor cortex maps in M1 depends on sensory feedback from somatosensory maps.

  8. Motor cortex changes in spinal cord injury: a TMS study.

    Science.gov (United States)

    Saturno, Eleonora; Bonato, Claudio; Miniussi, Carlo; Lazzaro, Vincenzodi; Callea, Leonardo

    2008-12-01

    Using paired pulse transcranial magnetic stimulation (TMS) paradigms, we studied cortical excitability in a patient with spinal cord lesion. During posterior tibial nerve stimulation, the contextual flexion of hand fingers contralateral to the stimulated lower limb had suggested a change in motor cortex excitability. Results showed a decrease in the activity of motor cortex inhibitory circuits. This could suggest that in spinal cord injury, just as in stroke and peripheral deafferentation, a disinhibition of latent synapses within the motor cortex and the rewriting of a new motor map can occur.

  9. Bilateral lesions of the central but not anterior or posterior parts of the piriform cortex retard amygdala kindling in rats.

    Science.gov (United States)

    Schwabe, K; Ebert, U; Löscher, W

    2000-01-01

    The piriform cortex is thought to be involved in temporal lobe seizure propagation, such as that occurring during kindling of the amygdala or hippocampus. A number of observations suggested that the circuits of the piriform cortex might act as a critical pathway for limbic seizure discharges to assess motor systems, but direct evidence for this suggestion is scarce. Furthermore, the piriform cortex is not a homogeneous structure, which complicates studies on its role in limbic epileptogenesis. We have previously reported data indicating that the central part of the piriform cortex might be particularly involved during amygdala kindling. In order to further evaluate the role of different parts of the piriform cortex during kindling development, we bilaterally destroyed either the central, anterior or posterior piriform cortex by microinjections of ibotenate two weeks before onset of amygdala kindling. Lesions of the anterior piriform cortex hardly affected kindling acquisition, except that fewer animals exhibited stage 3 (unilateral forelimb) seizures compared to sham controls. Lesions of the central piriform cortex significantly retarded kindling, which was due to a decreased progression from stage 3 to stage 4/5 seizures, i.e. the lesioned rats needed significantly longer for the acquisition of generalized clonic seizures in the late stages of kindling development. Lesions of the posterior piriform cortex did not significantly affect kindling development. The data demonstrate that different parts of the piriform cortex mediate qualitatively different effects on amygdala kindling. The central piriform cortex seems to be a neural substrate involved in the continuous development of kindling from stage 3 to stages 4/5, indicating that this part of the piriform cortex may have preferred access, either directly or indirectly, to structures capable of supporting generalized kindled seizure expression.

  10. The auditory representation of speech sounds in human motor cortex

    Science.gov (United States)

    Cheung, Connie; Hamilton, Liberty S; Johnson, Keith; Chang, Edward F

    2016-01-01

    In humans, listening to speech evokes neural responses in the motor cortex. This has been controversially interpreted as evidence that speech sounds are processed as articulatory gestures. However, it is unclear what information is actually encoded by such neural activity. We used high-density direct human cortical recordings while participants spoke and listened to speech sounds. Motor cortex neural patterns during listening were substantially different than during articulation of the same sounds. During listening, we observed neural activity in the superior and inferior regions of ventral motor cortex. During speaking, responses were distributed throughout somatotopic representations of speech articulators in motor cortex. The structure of responses in motor cortex during listening was organized along acoustic features similar to auditory cortex, rather than along articulatory features as during speaking. Motor cortex does not contain articulatory representations of perceived actions in speech, but rather, represents auditory vocal information. DOI: http://dx.doi.org/10.7554/eLife.12577.001 PMID:26943778

  11. Speech dynamics are coded in the left motor cortex in fluent speakers but not in adults who stutter.

    Science.gov (United States)

    Neef, Nicole E; Hoang, T N Linh; Neef, Andreas; Paulus, Walter; Sommer, Martin

    2015-03-01

    The precise excitability regulation of neuronal circuits in the primary motor cortex is central to the successful and fluent production of speech. Our question was whether the involuntary execution of undesirable movements, e.g. stuttering, is linked to an insufficient excitability tuning of neural populations in the orofacial region of the primary motor cortex. We determined the speech-related time course of excitability modulation in the left and right primary motor tongue representation. Thirteen fluent speakers (four females, nine males; aged 23-44) and 13 adults who stutter (four females, nine males, aged 21-55) were asked to build verbs with the verbal prefix 'auf'. Single-pulse transcranial magnetic stimulation was applied over the primary motor cortex during the transition phase between a fixed labiodental articulatory configuration and immediately following articulatory configurations, at different latencies after transition onset. Bilateral electromyography was recorded from self-adhesive electrodes placed on the surface of the tongue. Off-line, we extracted the motor evoked potential amplitudes and normalized these amplitudes to the individual baseline excitability during the fixed configuration. Fluent speakers demonstrated a prominent left hemisphere increase of motor cortex excitability in the transition phase (P = 0.009). In contrast, the excitability of the right primary motor tongue representation was unchanged. Interestingly, adults afflicted with stuttering revealed a lack of left-hemisphere facilitation. Moreover, the magnitude of facilitation was negatively correlated with stuttering frequency. Although orofacial midline muscles are bilaterally innervated from corticobulbar projections of both hemispheres, our results indicate that speech motor plans are controlled primarily in the left primary speech motor cortex. This speech motor planning-related asymmetry towards the left orofacial motor cortex is missing in stuttering. Moreover, a negative

  12. Neurophotonics applications to motor cortex research: a review

    OpenAIRE

    2014-01-01

    Abstract. Neurophotonics methods offer powerful ways to access neuronal signals and circuits. We highlight recent advances and current themes in this area, emphasizing tools for mapping, monitoring, and manipulating excitatory projection neurons and their synaptic circuits in mouse motor cortex.

  13. Primary Motor Cortex Involvement in Initial Learning during Visuomotor Adaptation

    Science.gov (United States)

    Riek, Stephan; Hinder, Mark R.; Carson, Richard G.

    2012-01-01

    Human motor behaviour is continually modified on the basis of errors between desired and actual movement outcomes. It is emerging that the role played by the primary motor cortex (M1) in this process is contingent upon a variety of factors, including the nature of the task being performed, and the stage of learning. Here we used repetitive TMS to…

  14. Ocular Motor Function in Patients with Bilateral Vestibular Weakness

    Directory of Open Access Journals (Sweden)

    Seyyed Amir Hossein Ghazizadeh Hashemi

    2016-05-01

    Full Text Available Introduction: Patients with bilateral weakness (BW have many difficulties in gaze stability that interfere with their normal function. The aim of this study was to evaluate ocular motor functions in patients with BW to better understand the problem of gaze instability in these patients.   Materials and Methods: Patients were referred from the Otolaryngology Department for Vestibular Assessment to our clinic between November 2014 and March 2015. We assessed ocular motor function (gaze, saccade, and smooth pursuit in patients over the age of 18 years with BW, as verified by a caloric test.   Results: Seventy-eight patients completed all the tests. The mean age of patients was 51.9 (±15.9 years, and 47 (60% were female. Abnormal results were found in five (6.4%, 32 (41%, and seven (9% patients with respect to gaze, smooth pursuit, and saccade, respectively. There were positive but relatively weak relationships between age and ocular motor results.   Conclusion:  Patients with BW suffer from dizziness and unsteadiness. These patients have abnormal function in ocular motor (especially smooth pursuit tests. The ocular motor dysfunction is responsible for gaze instability in static positions such as standing.

  15. Spontaneously Fluctuating Motor Cortex Excitability in Alternating Hemiplegia of Childhood: A Transcranial Magnetic Stimulation Study

    Science.gov (United States)

    Stern, William M.; Desikan, Mahalekshmi; Hoad, Damon; Jaffer, Fatima; Strigaro, Gionata; Sander, Josemir W.; Rothwell, John C.; Sisodiya, Sanjay M.

    2016-01-01

    Background Alternating hemiplegia of childhood is a very rare and serious neurodevelopmental syndrome; its genetic basis has recently been established. Its characteristic features include typically-unprovoked episodes of hemiplegia and other transient or more persistent neurological abnormalities. Methods We used transcranial magnetic stimulation to assess the effect of the condition on motor cortex neurophysiology both during and between attacks of hemiplegia. Nine people with alternating hemiplegia of childhood were recruited; eight were successfully tested using transcranial magnetic stimulation to study motor cortex excitability, using single and paired pulse paradigms. For comparison, data from ten people with epilepsy but not alternating hemiplegia, and ten healthy controls, were used. Results One person with alternating hemiplegia tested during the onset of a hemiplegic attack showed progressively diminishing motor cortex excitability until no response could be evoked; a second person tested during a prolonged bilateral hemiplegic attack showed unusually low excitability. Three people tested between attacks showed asymptomatic variation in cortical excitability, not seen in controls. Paired pulse paradigms, which probe intracortical inhibitory and excitatory circuits, gave results similar to controls. Conclusions We report symptomatic and asymptomatic fluctuations in motor cortex excitability in people with alternating hemiplegia of childhood, not seen in controls. We propose that such fluctuations underlie hemiplegic attacks, and speculate that the asymptomatic fluctuation we detected may be useful as a biomarker for disease activity. PMID:26999520

  16. The discovery of motor cortex and its background.

    Science.gov (United States)

    Gross, Charles G

    2007-01-01

    In 1870 Gustav Fritsch and Edvard Hitzig showed that electrical stimulation of the cerebral cortex of a dog produced movements. This was a crucial event in the development of modern neuroscience because it was the first good experimental evidence for a) cerebral cortex involvement in motor function, b) the electrical excitability of the cortex, c) topographic representation in the brain, and d) localization of function in different regions of the cerebral cortex. This paper discusses their experiment and some developments in the previous two centuries that led to it including the ideas of Thomas Willis and Emanuel Swedenborg, the widespread interest in electricity and the localizations of function of Franz Joseph Gall, John Hughlings Jackson, and Paul Broca. We also consider the subsequent study of the motor cortex by David Ferrier and others.

  17. The ipsilateral motor cortex contributes to cross-limb transfer of performance gains after ballistic motor practice.

    Science.gov (United States)

    Lee, Michael; Hinder, Mark R; Gandevia, Simon C; Carroll, Timothy J

    2010-01-01

    Although it has long been known that practicing a motor task with one limb can improve performance with the limb opposite, the mechanisms remain poorly understood. Here we tested the hypothesis that improved performance with the untrained limb on a fastest possible (i.e. ballistic) movement task depends partly on cortical circuits located ipsilateral to the trained limb. The idea that crossed effects, which are important for the learning process, might occur in the 'untrained' hemisphere following ballistic training is based on the observation that tasks requiring strong descending drive generate extensive bilateral cortical activity. Twenty-one volunteers practiced a ballistic index finger abduction task with their right hand, and corticospinal excitability was assessed in two hand muscles (first dorsal interosseus, FDI; adductor digiti minimi, ADM). Eight control subjects did not train. After training, repetitive transcranial magnetic stimulation (rTMS; 15 min at 1 Hz) was applied to the left (trained) or right (untrained) motor cortex to induce a 'virtual lesion'. A third training group received sham rTMS, and control subjects received rTMS to the right motor cortex. Performance and corticospinal excitability (for FDI) increased in both hands for training but not control subjects. rTMS of the left, trained motor cortex specifically reduced training-induced gains in motor performance for the right, trained hand, and rTMS of the right, untrained motor cortex specifically reduced performance gains for the left, untrained hand. Thus, cortical processes within the untrained hemisphere, ipsilateral to the trained hand, contribute to early retention of ballistic performance gains for the untrained limb.

  18. Similarities between GCS and human motor cortex: complex movement coordination

    Science.gov (United States)

    Rodríguez, Jose A.; Macias, Rosa; Molgo, Jordi; Guerra, Dailos

    2014-07-01

    The "Gran Telescopio de Canarias" (GTC1) is an optical-infrared 10-meter segmented mirror telescope at the ORM observatory in Canary Islands (Spain). The GTC control system (GCS), the brain of the telescope, is is a distributed object & component oriented system based on RT-CORBA and it is responsible for the management and operation of the telescope, including its instrumentation. On the other hand, the Human motor cortex (HMC) is a region of the cerebrum responsible for the coordination of planning, control, and executing voluntary movements. If we analyze both systems, as far as the movement control of their mechanisms and body parts is concerned, we can find extraordinary similarities in their architectures. Both are structured in layers, and their functionalities are comparable from the movement conception until the movement action itself: In the GCS we can enumerate the Sequencer high level components, the Coordination libraries, the Control Kit library and the Device Driver library as the subsystems involved in the telescope movement control. If we look at the motor cortex, we can also enumerate the primary motor cortex, the secondary motor cortices, which include the posterior parietal cortex, the premotor cortex, and the supplementary motor area (SMA), the motor units, the sensory organs and the basal ganglia. From all these components/areas we will analyze in depth the several subcortical regions, of the the motor cortex, that are involved in organizing motor programs for complex movements and the GCS coordination framework, which is composed by a set of classes that allow to the high level components to transparently control a group of mechanisms simultaneously.

  19. Motor cortex hyperexcitability to transcranial magnetic stimulation in Alzheimer's disease.

    Science.gov (United States)

    Di Lazzaro, V; Oliviero, A; Pilato, F; Saturno, E; Dileone, M; Marra, C; Daniele, A; Ghirlanda, S; Gainotti, G; Tonali, P A

    2004-04-01

    Recent transcranial magnetic stimulation (TMS) studies demonstrate that motor cortex excitability is increased in Alzheimer's disease (AD) and that intracortical inhibitory phenomena are impaired. The aim of the present study was to determine whether hyperexcitability is due to the impairment of intracortical inhibitory circuits or to an independent abnormality of excitatory circuits. We assessed the excitability of the motor cortex with TMS in 28 patients with AD using several TMS paradigms and compared the data of cortical excitability (evaluated by measuring resting motor threshold) with the amount of motor cortex disinhibition as evaluated using the test for motor cortex cholinergic inhibition (short latency afferent inhibition) and GABAergic inhibition (short latency intracortical inhibition). The data in AD patients were also compared with that from 12 age matched healthy individuals. The mean resting motor threshold was significantly lower in AD patients than in controls. The amount of short latency afferent inhibition was significantly smaller in AD patients than in normal controls. There was also a tendency for AD patients to have less pronounced short latency intracortical inhibition than controls, but this difference was not significant. There was no correlation between resting motor threshold and measures of either short latency afferent or intracortical inhibition (r = -0.19 and 0.18 respectively, NS). In 14 AD patients the electrophysiological study was repeated after a single oral dose of the cholinesterase inhibitor rivastigmine. Resting motor threshold was not significantly modified by the administration of rivastigmine. In contrast, short latency afferent inhibition from the median nerve was significantly increased by the administration of rivastigmine. The change in threshold did not seem to correlate with dysfunction of inhibitory intracortical cholinergic and GABAergic circuits, nor with the central cholinergic activity. We propose that the

  20. Repetitive Transcranial Magnetic Stimulation to the Primary Motor Cortex Interferes with Motor Learning by Observing

    Science.gov (United States)

    Brown, Liana E.; Wilson, Elizabeth T.; Gribble, Paul L.

    2009-01-01

    Neural representations of novel motor skills can be acquired through visual observation. We used repetitive transcranial magnetic stimulation (rTMS) to test the idea that this "motor learning by observing" is based on engagement of neural processes for learning in the primary motor cortex (M1). Human subjects who observed another person learning…

  1. The effect of tumour type and distance on activation in the motor cortex

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Wen-Ching; Feldman, Susan C.; Zimmerman, Aphrodite; Sinensky, Rebecca; Rao, Satyaveni [University of Medicine and Dentistry of New Jersey, Department of Radiology, Newark, NJ (United States); Schulder, Michael [University of Medicine and Dentistry of New Jersey, Department of Neurosurgery, Newark, NJ (United States); Kalnin, Andrew J. [University of Medicine and Dentistry of New Jersey, Department of Radiology, Newark, NJ (United States); Indiana University, School of Medicine, Department of Radiology, Indianapolis, IN (United States); Holodny, Andrei I. [University of Medicine and Dentistry of New Jersey, Department of Radiology, Newark, NJ (United States); Memorial-Sloan Kettering Cancer Center, Department of Radiology, New York, NY (United States)

    2005-11-01

    Functional MRI has been widely used to identify the eloquent cortex in neurosurgical/radiosurgical planning and treatment of CNS neoplasms and malformations. In this study we examined the effect of CNS tumours on the blood oxygenation level-dependent (BOLD) activation maps in the primary and supplementary motor cortex. A total of 33 tumour patients and five healthy right-handed adults were enrolled in the study. Patients were divided into four groups based on tumour type and distance from primary motor cortex: (1) intra-axial, near, (2) extra-axial, near, (3) intra-axial, far and (4) extra-axial, far. The intra-axial groups consisted of patients with astrocytomas, glioblastomas and metastatic tumours of mixed histology; all the extra-axial tumours were meningiomas. The motor task was a bilateral, self-paced, finger-tapping paradigm. Anatomical and functional data were acquired with a 1.5 T GE Echospeed scanner. Maps of the motor areas were derived from the BOLD images, using SPM99 software. For each subject we first determined the activation volume in the primary motor area and the supplementary motor area (SMA) and then calculated the percentage difference between the hemispheres. Two factors influenced the activation volumes: tumour type (P<0.04) and distance from the eloquent cortex (P<0.06). Patients in group 1 (intra-axial, near) had the smallest activation area in the primary motor cortex, the greatest percentage difference in the activation volume between the hemispheres, and the largest activation volume in the SMA. Patients in group 4 (extra-axial, far) had the largest activation volume in the primary motor cortex, the least percentage difference in volume between the hemispheres, and the smallest activation volume in the SMA. There was no significant change in the volume of the SMA in any group, compared with controls, suggesting that, although there is a gradual decrease in SMA volume with distance from the primary motor area, the effect on motor

  2. Transcranial static magnetic field stimulation of the human motor cortex.

    Science.gov (United States)

    Oliviero, Antonio; Mordillo-Mateos, Laura; Arias, Pablo; Panyavin, Ivan; Foffani, Guglielmo; Aguilar, Juan

    2011-10-15

    The aim of the present study was to investigate in healthy humans the possibility of a non-invasive modulation of motor cortex excitability by the application of static magnetic fields through the scalp. Static magnetic fields were obtained by using cylindrical NdFeB magnets. We performed four sets of experiments. In Experiment 1, we recorded motor potentials evoked by single-pulse transcranial magnetic stimulation (TMS) of the motor cortex before and after 10 min of transcranial static magnetic field stimulation (tSMS) in conscious subjects. We observed an average reduction of motor cortex excitability of up to 25%, as revealed by TMS, which lasted for several minutes after the end of tSMS, and was dose dependent (intensity of the magnetic field) but not polarity dependent. In Experiment 2, we confirmed the reduction of motor cortex excitability induced by tSMS using a double-blind sham-controlled design. In Experiment 3, we investigated the duration of tSMS that was necessary to modulate motor cortex excitability. We found that 10 min of tSMS (compared to 1 min and 5 min) were necessary to induce significant effects. In Experiment 4, we used transcranial electric stimulation (TES) to establish that the tSMS-induced reduction of motor cortex excitability was not due to corticospinal axon and/or spinal excitability, but specifically involved intracortical networks. These results suggest that tSMS using small static magnets may be a promising tool to modulate cerebral excitability in a non-invasive, painless, and reversible way.

  3. The involvement of primary motor cortex in mental rotation revealed by transcranial magnetic stimulation

    OpenAIRE

    Eisenegger, Christoph; Herwig, Uwe; Jäncke, Lutz

    2007-01-01

    We used single-pulse transcranial magnetic stimulation of the left primary hand motor cortex and motor evoked potentials of the contralateral right abductor pollicis brevis to probe motor cortex excitability during a standard mental rotation task. Based on previous findings we tested the following hypotheses. (i) Is the hand motor cortex activated more strongly during mental rotation than during reading aloud or reading silently? The latter tasks have been shown to increase motor cortex excit...

  4. Long-term motor cortex stimulation for phantom limb pain.

    Science.gov (United States)

    Pereira, Erlick A C; Moore, Tom; Moir, Liz; Aziz, Tipu Z

    2015-04-01

    We present the long-term course of motor cortex stimulation to relieve a case of severe burning phantom arm pain after brachial plexus injury and amputation. During 16-year follow-up the device continued to provide efficacious analgesia. However, several adjustments of stimulation parameters were required, as were multiple pulse generator changes, antibiotics for infection and one electrode revision due to lead migration. Steady increases in stimulation parameters over time were required. One of the longest follow-ups of motor cortex stimulation is described; the case illustrates challenges and pitfalls in neuromodulation for chronic pain, demonstrating strategies for maintaining analgesia and overcoming tolerance.

  5. Motor learning in animal models of Parkinson's disease: Aberrant synaptic plasticity in the motor cortex.

    Science.gov (United States)

    Xu, Tonghui; Wang, Shaofang; Lalchandani, Rupa R; Ding, Jun B

    2017-04-01

    In Parkinson's disease (PD), dopamine depletion causes major changes in the brain, resulting in the typical cardinal motor features of the disease. PD neuropathology has been restricted to postmortem examinations, which are limited to only a single time of PD progression. Models of PD in which dopamine tone in the brain is chemically or physically disrupted are valuable tools in understanding the mechanisms of the disease. The basal ganglia have been well studied in the context of PD, and circuit changes in response to dopamine loss have been linked to the motor dysfunctions in PD. However, the etiology of the cognitive dysfunctions that are comorbid in PD patients has remained unclear until now. In this article, we review recent studies exploring how dopamine depletion affects the motor cortex at the synaptic level. In particular, we highlight our recent findings on abnormal spine dynamics in the motor cortex of PD mouse models through in vivo time-lapse imaging and motor skill behavior assays. In combination with previous studies, a role of the motor cortex in skill learning and the impairment of this ability with the loss of dopamine are becoming more apparent. Taken together, we conclude with a discussion on the potential role for the motor cortex in PD, with the possibility of targeting the motor cortex for future PD therapeutics. © 2017 International Parkinson and Movement Disorder Society. © 2017 International Parkinson and Movement Disorder Society.

  6. Bilateral Transcranial Magnetic Stimulation of the Prefrontal Cortex reduces cocaine intake: a pilot study.

    Directory of Open Access Journals (Sweden)

    Corinna Bolloni

    2016-08-01

    Full Text Available Background: Chronic cocaine consumption is associated to a decrease in mesolimbic dopamine transmission that maintains drug intake. Transcranial Magnetic Stimulation (TMS is gaining reliability a useful therapeutic tool in drug addiction since it can modulate cortico-limbic activity resulting in reduction of drug craving. Aims: In the present study we investigated the therapeutic effect of bilateral TMS of prefrontal cortex (PFC in reducing cocaine intake, in a sample of treatment-seeking patients with current cocaine use disorder (DSM-V. Methods: 10 cocaine addicts (DSM-V were randomly assigned to the active or sham stimulation protocol in a double-blind experimental design. Twelve repetitive TMS (rTMS sessions were administered 3 times a week for 4 weeks at 100% of motor threshold, over bilateral PFC. Cocaine intake (ng/mg was assessed by hair analysis at baseline (before treatment, T0, after one month (end of treatment, T1, 3 (T2 and 6 (T3 months later. All subjects received psychological support weekly. Results: The two-way ANOVA for repeated measures did not show a significant effect of the interaction between time and treatment (F4,32= 0.35; p=.87. Despite that result indicated no difference in the effect of the two conditions (active vs sham along time, a decreasing trend in cocaine consumption in active TMS group (F3,23=3.42; p=.04 vs sham (F3,15=1.88; p=.20 was observed when we performed exploratory analysis with time as factor . Indeed, Post-hoc comparisons showed a significant reduction in the amount of cocaine detected from the onset to three months later (T0-T2; p=.02 and to the end of treatment (T0-T3; p=.01 in addicts from the active group. Conclusions: Bilateral rTMS of PFC at 10 Hz did not show a significant effect on cocaine intake compared to sham. However, a long-term reduction in cocaine intake in active TMS treated patients was observed when we considered the time as factor. Further studies are required to confirm these

  7. Induction of motor associative plasticity in the posterior parietal cortex-primary motor network

    DEFF Research Database (Denmark)

    Chao, Chi-Chao; Karabanov, Anke Ninija; Paine, Rainer

    2015-01-01

    There is anatomical and functional connectivity between the primary motor cortex (M1) and posterior parietal cortex (PPC) that plays a role in sensorimotor integration. In this study, we applied corticocortical paired-associative stimuli to ipsilateral PPC and M1 (parietal ccPAS) in healthy right...

  8. Parietal transcranial direct current stimulation modulates primary motor cortex excitability.

    Science.gov (United States)

    Rivera-Urbina, Guadalupe Nathzidy; Batsikadze, Giorgi; Molero-Chamizo, Andrés; Paulus, Walter; Kuo, Min-Fang; Nitsche, Michael A

    2015-03-01

    The posterior parietal cortex is part of the cortical network involved in motor learning and is structurally and functionally connected with the primary motor cortex (M1). Neuroplastic alterations of neuronal connectivity might be an important basis for learning processes. These have however not been explored for parieto-motor connections in humans by transcranial direct current stimulation (tDCS). Exploring tDCS effects on parieto-motor cortical connectivity might be functionally relevant, because tDCS has been shown to improve motor learning. We aimed to explore plastic alterations of parieto-motor cortical connections by tDCS in healthy humans. We measured neuroplastic changes of corticospinal excitability via motor evoked potentials (MEP) elicited by single-pulse transcranial magnetic stimulation (TMS) before and after tDCS over the left posterior parietal cortex (P3), and 3 cm posterior or lateral to P3, to explore the spatial specificity of the effects. Furthermore, short-interval intracortical inhibition/intracortical facilitation (SICI/ICF) over M1, and parieto-motor cortical connectivity were obtained before and after P3 tDCS. The results show polarity-dependent M1 excitability alterations primarily after P3 tDCS. Single-pulse TMS-elicited MEPs, M1 SICI/ICF at 5 and 7 ms and 10 and 15 ms interstimulus intervals (ISIs), and parieto-motor connectivity at 10 and 15 ms ISIs were all enhanced by anodal stimulation. Single pulse-TMS-elicited MEPs, and parieto-motor connectivity at 10 and 15 ms ISIs were reduced by cathodal tDCS. The respective corticospinal excitability alterations lasted for at least 120 min after stimulation. These results show an effect of remote stimulation of parietal areas on M1 excitability. The spatial specificity of the effects and the impact on parietal cortex-motor cortex connections suggest a relevant connectivity-driven effect.

  9. Projection from the perirhinal cortex to the frontal motor cortex in the rat.

    Science.gov (United States)

    Kyuhou, Shin ichi; Gemba, Hisae

    2002-03-01

    Stimulation of the anterior perirhinal cortex (PERa) induced marked surface-negative and depth-positive field potentials in the rat frontal motor cortex (MC) including the rostral and caudal forelimb areas. Injection of biotinylated dextran into the PERa densely labeled axon terminals in the superficial layers of the MC, where vigorous unit responses were evoked after PERa stimulation, indicated that the perirhinal-frontal projection preferentially activates the superficial layer neurons of the MC.

  10. Motor cortex and spinal cord neuromodulation promote corticospinal tract axonal outgrowth and motor recovery after cervical contusion spinal cord injury.

    Science.gov (United States)

    Zareen, N; Shinozaki, M; Ryan, D; Alexander, H; Amer, A; Truong, D Q; Khadka, N; Sarkar, A; Naeem, S; Bikson, M; Martin, J H

    2017-08-10

    Cervical injuries are the most common form of SCI. In this study, we used a neuromodulatory approach to promote skilled movement recovery and repair of the corticospinal tract (CST) after a moderately severe C4 midline contusion in adult rats. We used bilateral epidural intermittent theta burst (iTBS) electrical stimulation of motor cortex to promote CST axonal sprouting and cathodal trans-spinal direct current stimulation (tsDCS) to enhance spinal cord activation to motor cortex stimulation after injury. We used Finite Element Method (FEM) modeling to direct tsDCS to the cervical enlargement. Combined iTBS-tsDCS was delivered for 30min daily for 10days. We compared the effect of stimulation on performance in the horizontal ladder and the Irvine Beattie and Bresnahan forepaw manipulation tasks and CST axonal sprouting in injury-only and injury+stimulation animals. The contusion eliminated the dorsal CST in all animals. tsDCS significantly enhanced motor cortex evoked responses after C4 injury. Using this combined spinal-M1 neuromodulatory approach, we found significant recovery of skilled locomotion and forepaw manipulation skills compared with injury-only controls. The spared CST axons caudal to the lesion in both animal groups derived mostly from lateral CST axons that populated the contralateral intermediate zone. Stimulation enhanced injury-dependent CST axonal outgrowth below and above the level of the injury. This dual neuromodulatory approach produced partial recovery of skilled motor behaviors that normally require integration of posture, upper limb sensory information, and intent for performance. We propose that the motor systems use these new CST projections to control movements better after injury. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Neuroplasticity Changes on Human Motor Cortex Induced by Acupuncture Therapy: A Preliminary Study.

    Science.gov (United States)

    Yang, Yi; Eisner, Ines; Chen, Siqi; Wang, Shaosong; Zhang, Fan; Wang, Linpeng

    2017-01-01

    While neuroplasticity changes measured by transcranial magnetic stimulation have been proved to be highly correlated to motor recovery and have been tested in various forms of interventions, it has not been applied to investigate the neurophysiologic mechanism of acupuncture therapy. The aim of this study is to investigate neuroplasticity changes induced by a single session of acupuncture therapy in healthy adults, regarding the excitability change on bilateral primary motor cortex and interhemispheric inhibition. Ten subjects took a 30-minute acupuncture therapy and the same length relaxing phase in separate days. Transcranial magnetic stimulation measures, including resting motor threshold, amplitudes of motor-evoked potential, and interhemispheric inhibition, were assessed before and 10 minutes after intervention. Acupuncture treatment showed significant changes on potential amplitude from both ipsilateral and contralateral hemispheres to acupuncture compared to baseline. Also, interhemispheric inhibition from the contralateral motor cortex to the opposite showed a significant decline. The results indicated that corticomotoneuronal excitability and interhemispheric competition could be modulated by acupuncture therapy on healthy subjects. The following question about whether these changes will be observed in the same way on stroke patients and whether they correlate with the therapeutic effect on movement need to be answered by following studies. This trial is registered with ISRCTN13074245.

  12. Motor Cortex Stimulation Reverses Maladaptive Plasticity Following Spinal Cord Injury

    Science.gov (United States)

    2011-09-01

    etic neuralgia [5], brachial plexus, and phantom limb pain [53]. Stimulation of other brain structures has also been used for the treatment of...Verdie JC, Mascott C, Lazorthes Y. Chronic motor cortex stimulation for phantom limb pain: correlations between pain relief and functional imaging...G, Thompson, SM (2008) Maladaptive homeostatic plasticity in a rodent model of central pain syndrome : thalamic hyperexcitability after

  13. TMS: a navigator for NIRS of the primary motor cortex?

    NARCIS (Netherlands)

    Koenraadt, K.L.; Munneke, M.; Duysens, J.E.J.; Keijsers, N.L.W.

    2011-01-01

    Near-infrared spectroscopy (NIRS) is a non-invasive optical imaging technique, which is increasingly used to measure hemodynamic responses in the motor cortex. The location at which the NIRS optodes are placed on the skull is a major factor in measuring the hemodynamic responses optimally. In this s

  14. Modification of motor cortex excitability during muscle relaxation in motor learning.

    Science.gov (United States)

    Sugawara, Kenichi; Tanabe, Shigeo; Suzuki, Tomotaka; Saitoh, Kei; Higashi, Toshio

    2016-01-01

    We postulated that gradual muscle relaxation during motor learning would dynamically change activity in the primary motor cortex (M1) and modify short-interval intracortical inhibition (SICI). Thus, we compared changes in M1 excitability both pre and post motor learning during gradual muscle relaxation. Thirteen healthy participants were asked to gradually relax their muscles from an isometric right wrist extension (30% maximum voluntary contraction; MVC) using a tracking task for motor learning. Single or paired transcranial magnetic stimulation (TMS) was applied at either 20% or 80% of the downward force output during muscle release from 30% MVC, and we compared the effects of motor learning immediately after the 1st and 10th blocks. Motor-evoked potentials (MEPs) from the extensor and flexor carpi radialis (ECR and FCR) were then measured and compared to evaluate their relationship before and after motor learning. In both muscles and each downward force output, motor cortex excitability during muscle relaxation was significantly increased following motor learning. In the ECR, the SICI in the 10th block was significantly increased during the 80% waveform decline compared to the SICI in the 1st block. In the FCR, the SICI also exhibited a greater inhibitory effect when muscle relaxation was terminated following motor learning. During motor training, acquisition of the ability to control muscle relaxation increased the SICI in both the ECR and FCR during motor termination. This finding aids in our understanding of the cortical mechanisms that underlie muscle relaxation during motor learning.

  15. Dopamine Promotes Motor Cortex Plasticity and Motor Skill Learning via PLC Activation.

    Science.gov (United States)

    Rioult-Pedotti, Mengia-Seraina; Pekanovic, Ana; Atiemo, Clement Osei; Marshall, John; Luft, Andreas Rüdiger

    2015-01-01

    Dopaminergic neurons in the ventral tegmental area, the major midbrain nucleus projecting to the motor cortex, play a key role in motor skill learning and motor cortex synaptic plasticity. Dopamine D1 and D2 receptor antagonists exert parallel effects in the motor system: they impair motor skill learning and reduce long-term potentiation. Traditionally, D1 and D2 receptor modulate adenylyl cyclase activity and cyclic adenosine monophosphate accumulation in opposite directions via different G-proteins and bidirectionally modulate protein kinase A (PKA), leading to distinct physiological and behavioral effects. Here we show that D1 and D2 receptor activity influences motor skill acquisition and long term synaptic potentiation via phospholipase C (PLC) activation in rat primary motor cortex. Learning a new forelimb reaching task is severely impaired in the presence of PLC, but not PKA-inhibitor. Similarly, long term potentiation in motor cortex, a mechanism involved in motor skill learning, is reduced when PLC is inhibited but remains unaffected by the PKA inhibitor. Skill learning deficits and reduced synaptic plasticity caused by dopamine antagonists are prevented by co-administration of a PLC agonist. These results provide evidence for a role of intracellular PLC signaling in motor skill learning and associated cortical synaptic plasticity, challenging the traditional view of bidirectional modulation of PKA by D1 and D2 receptors. These findings reveal a novel and important action of dopamine in motor cortex that might be a future target for selective therapeutic interventions to support learning and recovery of movement resulting from injury and disease.

  16. Dopamine Promotes Motor Cortex Plasticity and Motor Skill Learning via PLC Activation.

    Directory of Open Access Journals (Sweden)

    Mengia-Seraina Rioult-Pedotti

    Full Text Available Dopaminergic neurons in the ventral tegmental area, the major midbrain nucleus projecting to the motor cortex, play a key role in motor skill learning and motor cortex synaptic plasticity. Dopamine D1 and D2 receptor antagonists exert parallel effects in the motor system: they impair motor skill learning and reduce long-term potentiation. Traditionally, D1 and D2 receptor modulate adenylyl cyclase activity and cyclic adenosine monophosphate accumulation in opposite directions via different G-proteins and bidirectionally modulate protein kinase A (PKA, leading to distinct physiological and behavioral effects. Here we show that D1 and D2 receptor activity influences motor skill acquisition and long term synaptic potentiation via phospholipase C (PLC activation in rat primary motor cortex. Learning a new forelimb reaching task is severely impaired in the presence of PLC, but not PKA-inhibitor. Similarly, long term potentiation in motor cortex, a mechanism involved in motor skill learning, is reduced when PLC is inhibited but remains unaffected by the PKA inhibitor. Skill learning deficits and reduced synaptic plasticity caused by dopamine antagonists are prevented by co-administration of a PLC agonist. These results provide evidence for a role of intracellular PLC signaling in motor skill learning and associated cortical synaptic plasticity, challenging the traditional view of bidirectional modulation of PKA by D1 and D2 receptors. These findings reveal a novel and important action of dopamine in motor cortex that might be a future target for selective therapeutic interventions to support learning and recovery of movement resulting from injury and disease.

  17. Reorganization of human motor cortex after hand replantation.

    Science.gov (United States)

    Röricht, S; Machetanz, J; Irlbacher, K; Niehaus, L; Biemer, E; Meyer, B U

    2001-08-01

    In 10 patients, reorganizational changes of the motor cortex contralateral to a replanted hand (MCreplant) were studied one to 14 years after complete traumatic amputation and consecutive successful replantation of the hand. The organizational state of MCreplant was assessed for the deafferentated and peripherally deefferentated hand-associated motor cortex and the adjacent motor representation of the proximal arm. For this, response maps were established for the first dorsal interosseus and biceps brachii muscle using focal transcranial magnetic stimulation (TMS) on a skull surface grid. Characteristics of the maps were center of gravity (COG), number of effective stimulation sites, amplitude sum, and amplitudes and response threshold at the optimal stimulation point. The COG is defined by the spatial distribution of response amplitudes on the map and lies over the cortex region with the most excitable corticospinal neurones supplying the recorded muscle. The COG of the biceps map in MCreplant was shifted laterally by 9.8 +/- 3.6 mm (range 5.0-15.7 mm). The extension of the biceps map in MCreplant was increased and the responses were enlarged and had lowered thresholds. For the muscles of the replanted hand, the pattern of reorganization was different: Response amplitudes were enlarged but thresholds, COG, and area of the cortical response map were normal. The different reorganizational phenomena observed for the motor cortical areas supplying the replanted hand and the biceps brachii of the same arm may be influenced by a different extent of deafferentation and by their different role in hand motor control.

  18. Laterality Differences in Cerebellar-Motor Cortex Connectivity.

    Science.gov (United States)

    Schlerf, John E; Galea, Joseph M; Spampinato, Danny; Celnik, Pablo A

    2015-07-01

    Lateralization of function is an important organizational feature of the motor system. Each effector is predominantly controlled by the contralateral cerebral cortex and the ipsilateral cerebellum. Transcranial magnetic stimulation studies have revealed hemispheric differences in the stimulation strength required to evoke a muscle response from the primary motor cortex (M1), with the dominant hemisphere typically requiring less stimulation than the nondominant. The current study assessed whether the strength of the connection between the cerebellum and M1 (CB-M1), known to change in association with motor learning, have hemispheric differences and whether these differences have any behavioral correlate. We observed, in right-handed individuals, that the connection between the right cerebellum and left M1 is typically stronger than the contralateral network. Behaviorally, we detected no lateralized learning processes, though we did find a significant effect on the amplitude of reaching movements across hands. Furthermore, we observed that the strength of the CB-M1 connection is correlated with the amplitude variability of reaching movements, a measure of movement precision, where stronger connectivity was associated with better precision. These findings indicate that lateralization in the motor system is present beyond the primary motor cortex, and points to an association between cerebellar M1 connectivity and movement execution. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  19. Neural Dynamics and Information Representation in Microcircuits of Motor Cortex

    Directory of Open Access Journals (Sweden)

    Yasuhiro eTsubo

    2013-05-01

    Full Text Available The brain has to analyze and respond to external events that can change rapidly from time to time, suggesting that information processing by the brain may be essentially dynamic rather than static. The dynamical features of neural computation are of significant importance in motor cortex that governs the process of movement generation and learning. In this paper, we discuss these features based primarily on our recent findings on neural dynamics and information coding in the microcircuit of rat motor cortex. In fact, cortical neurons show a variety of dynamical behavior from rhythmic activity in various frequency bands to highly irregular spike firing. Of particular interest are the similarity and dissimilarity of the neuronal response properties in different layers of motor cortex. By conducting electrophysiological recordings in slice preparation, we report the phase response curves of neurons in different cortical layers to demonstrate their layer-dependent synchronization properties. We then study how motor cortex recruits task-related neurons in different layers for voluntary arm movements by simultaneous juxtacellular and multiunit recordings from behaving rats. The results suggest an interesting difference in the spectrum of functional activity between the superficial and deep layers. Furthermore, the task-related activities recorded from various layers exhibited power law distributions of inter-spike intervals (ISIs, in contrast to a general belief that ISIs obey Poisson or Gamma distributions in cortical neurons. We present a theoretical argument that this power law of in vivo neurons may represent the maximization of the entropy of firing rate with limited energy consumption of spike generation. Though further studies are required to fully clarify the functional implications of this coding principle, it may shed new light on information representations by neurons and circuits in motor cortex.

  20. A systematic review of non-motor rTMS induced motor cortex plasticity

    Directory of Open Access Journals (Sweden)

    Gregory eNordmann

    2015-07-01

    Full Text Available Motor cortex excitability can be measured by single- and paired-pulse transcranial magnetic stimulation (TMS. Repetitive transcranial magnetic stimulation (rTMS can induce neuroplastic effects in stimulated and in functionally connected cortical regions. Due to its ability to non-invasively modulate cortical activity, rTMS has been investigated for the treatment of various neurological and psychiatric disorders. However, such studies revealed a high variability of both clinical and neuronal effects induced by rTMS. In order to better elucidate this meta-plasticity, rTMS-induced changes in motor cortex excitability have been monitored in various studies in a pre-post stimulation design. Here, we give a systematic literature review (April 2014 of 29 studies investigating motor cortex excitability changes as a neuronal marker for rTMS effects over non-motor cortical areas. The majority of the studies focused on the stimulation of one of three separate cortical areas: the prefrontal area (17 studies, the cerebellum (8 studies, or the temporal cortex (3 studies. One study assessed the effects of multi-site rTMS. Most studies investigated healthy controls but some also stimulated patients with neuropsychiatric conditions (e.g., affective disorders, tinnitus. Methods and findings of the identified studies were highly variable showing no clear systematic pattern of interaction of non-motor rTMS with measures of motor cortex excitability. Based on the available literature, the measurement of motor cortex excitability changes before and after non-motor rTMS has only limited value in the investigation of rTMS related meta-plasticity as a neuronal state or as a trait marker for neuropsychiatric diseases. Our results do not suggest that there are systematic alterations of cortical excitability changes during rTMS treatment, which calls into question the practice of re-adjusting the stimulation intensity according to the motor threshold over the course of the

  1. Eye muscle proprioception is represented bilaterally in the sensorimotor cortex

    DEFF Research Database (Denmark)

    Balslev, Daniela; Albert, Neil B; Miall, Chris

    2011-01-01

    The cortical representation of eye position is still uncertain. In the monkey a proprioceptive representation of the extraocular muscles (EOM) of an eye were recently found within the contralateral central sulcus. In humans, we have previously shown a change in the perceived position of the right...... eye after a virtual lesion with rTMS over the left somatosensory area. However, it is possible that the proprioceptive representation of the EOM extends to other brain sites, which were not examined in these previous studies. The aim of this fMRI study was to sample the whole brain to identify...... the proprioceptive representation for the left and the right eye separately. Data were acquired while passive eye movement was used to stimulate EOM proprioceptors in the absence of a motor command. We also controlled for the tactile stimulation of the eyelid by removing from the analysis voxels activated by eyelid...

  2. Response of SI cortex to ipsilateral, contralateral and bilateral flutter stimulation in the cat

    Directory of Open Access Journals (Sweden)

    Favorov Oleg

    2005-04-01

    Full Text Available Abstract Background While SII cortex is considered to be the first cortical stage of the pathway that integrates tactile information arising from both sides of the body, SI cortex is generally not considered as a region in which neuronal response is modulated by simultaneous stimulation of bilateral (and mirror-image skin sites. Results Optical intrinsic signal imaging was used to evaluate the response of SI and SII in the same hemisphere to 25 Hz sinusoidal vertical skin displacement stimulation ("skin flutter" applied contralaterally, ipsilaterally, and bilaterally (simultaneously to the central pads of the forepaws. A localized increase in absorbance in both SI and SII occurred in response to both contralateral and bilateral flutter stimulation. Ipsilateral flutter stimulation evoked a localized increase in absorbance in SII, but little or no change in SI absorbance. In the forepaw representational region of SI, however, bilateral stimulation of the central pads evoked a response substantially smaller (approximately 30–35% smaller than the response to flutter stimulation of the contralateral central pad. Conclusion The finding that the response of SI cortex to bilateral central pad flutter stimulation is substantially smaller than the response evoked by a contralateral flutter stimulus, together with the recently published observation that a region located posteriorly in SII responds with a substantially larger response to a bilateral flutter stimulus than the response evoked from the contralateral central pad, lead us to propose that the SI activity evoked by contralateral skin stimulation is suppressed/inhibited (via corticocortical connections between SII and SI in the same hemisphere by the activity a simultaneous ipsilateral skin stimulus evokes in posterior SII.

  3. Are there excitability changes in the hand motor cortex during speech in left-handed subjects?

    Science.gov (United States)

    Tokimura, Hiroshi; Tokimura, Yoshika; Arita, Kazunori

    2012-01-01

    Hemispheric dominance was investigated in left-handed subjects using single transcranial magnetic stimulation to assess the possible effect of forced change in the dominant hand. Single transcranial magnetic stimuli were delivered randomly over the hand area of the left or right motor cortex of 8 Japanese self-declared left-handed adult volunteers. Electromyographic responses were recorded in the relaxed first dorsal interosseous muscle while the subjects read aloud. Laterality quotient calculated by the Edinburgh Inventory ranged from -100 to -5.26 and laterality index calculated from motor evoked potentials ranged from -86.2 to 38.8. There was no significant correlation between laterality quotient and laterality index. Mean data values across all 8 subjects indicated significant increases only in the left hand. Our ratio analysis of facilitation of the hand motor potentials showed that 2 each of the 8 self-declared left-handers were right- and left-hand dominant and the other 4 were bilateral-hand dominant. Speech dominancy was localized primarily in the right cerebral hemisphere in left-handed subjects, but some individuals exhibited bilateral or left dominance, possibly attributable to the forced change of hand preference for writing in childhood. Our findings suggest changes in the connections between the speech and hand motor areas.

  4. Visual attentional load influences plasticity in the human motor cortex.

    Science.gov (United States)

    Kamke, Marc R; Hall, Michelle G; Lye, Hayley F; Sale, Martin V; Fenlon, Laura R; Carroll, Timothy J; Riek, Stephan; Mattingley, Jason B

    2012-05-16

    Neural plasticity plays a critical role in learning, memory, and recovery from injury to the nervous system. Although much is known about the physical and physiological determinants of plasticity, little is known about the influence of cognitive factors. In this study, we investigated whether selective attention plays a role in modifying changes in neural excitability reflecting long-term potentiation (LTP)-like plasticity. We induced LTP-like effects in the hand area of the human motor cortex using transcranial magnetic stimulation (TMS). During the induction of plasticity, participants engaged in a visual detection task with either low or high attentional demands. Changes in neural excitability were assessed by measuring motor-evoked potentials in a small hand muscle before and after the TMS procedures. In separate experiments plasticity was induced either by paired associative stimulation (PAS) or intermittent theta-burst stimulation (iTBS). Because these procedures induce different forms of LTP-like effects, they allowed us to investigate the generality of any attentional influence on plasticity. In both experiments reliable changes in motor cortex excitability were evident under low-load conditions, but this effect was eliminated under high-attentional load. In a third experiment we investigated whether the attentional task was associated with ongoing changes in the excitability of motor cortex, but found no difference in evoked potentials across the levels of attentional load. Our findings indicate that in addition to their role in modifying sensory processing, mechanisms of attention can also be a potent modulator of cortical plasticity.

  5. Primary Motor Cortex Representation of Handgrip Muscles in Patients with Leprosy.

    Directory of Open Access Journals (Sweden)

    Vagner Wilian Batista E Sá

    Full Text Available Leprosy is an endemic infectious disease caused by Mycobacterium leprae that predominantly attacks the skin and peripheral nerves, leading to progressive impairment of motor, sensory and autonomic function. Little is known about how this peripheral neuropathy affects corticospinal excitability of handgrip muscles. Our purpose was to explore the motor cortex organization after progressive peripheral nerve injury and upper-limb dysfunction induced by leprosy using noninvasive transcranial magnetic stimulation (TMS.In a cross-sectional study design, we mapped bilaterally in the primary motor cortex (M1 the representations of the hand flexor digitorum superficialis (FDS, as well as of the intrinsic hand muscles abductor pollicis brevis (APB, first dorsal interosseous (FDI and abductor digiti minimi (ADM. All participants underwent clinical assessment, handgrip dynamometry and motor and sensory nerve conduction exams 30 days before mapping. Wilcoxon signed rank and Mann-Whitney tests were performed with an alpha-value of p<0.05.Dynamometry performance of the patients' most affected hand (MAH, was worse than that of the less affected hand (LAH and of healthy controls participants (p = 0.031, confirming handgrip impairment. Motor threshold (MT of the FDS muscle was higher in both hemispheres in patients as compared to controls, and lower in the hemisphere contralateral to the MAH when compared to that of the LAH. Moreover, motor evoked potential (MEP amplitudes collected in the FDS of the MAH were higher in comparison to those of controls. Strikingly, MEPs in the intrinsic hand muscle FDI had lower amplitudes in the hemisphere contralateral to MAH as compared to those of the LAH and the control group. Taken together, these results are suggestive of a more robust representation of an extrinsic hand flexor and impaired intrinsic hand muscle function in the hemisphere contralateral to the MAH due to leprosy.Decreased sensory-motor function induced by

  6. Transcranial direct current stimulation of the primary motor cortex improves word-retrieval in older adults.

    Directory of Open Access Journals (Sweden)

    Marcus eMeinzer

    2014-09-01

    Full Text Available Language facilitation by transcranial direct current stimulation (tDCS in healthy individuals has generated hope that tDCS may also allow improving language impairment after stroke (aphasia. However, current stimulation protocols have yielded variable results and may require identification of residual language cortex using functional magnetic resonance imaging (fMRI, which complicates incorporation into clinical practice. Based on previous behavioral studies that demonstrated improved language processing by motor system pre-activation, the present study assessed whether tDCS administered to the primary motor cortex (M1 can enhance language functions.This proof-of-concept study employed a sham-tDCS controlled, cross-over, within-subject design and assessed the impact of unilateral excitatory (anodal and bihemispheric (dual tDCS in eighteen healthy older adults during semantic word-retrieval and motor speech tasks. Simultaneous fMRI scrutinized the neural mechanisms underlying tDCS effects.Both active tDCS conditions significantly improved word-retrieval compared to sham-tDCS. The direct comparison of activity elicited by word-retrieval vs. motor-speech trials revealed bilateral frontal activity increases during both anodal- and dual-tDCS compared to sham-tDCS. This effect was driven by more pronounced deactivation of frontal regions during the motor-speech task, while activity during word-retrieval trials was unaffected by the stimulation. No effects were found in M1 and secondary motor regions.Our results show that tDCS administered to M1 can improve word-retrieval in healthy individuals, thereby providing a rationale to explore whether M1-tDCS may offer a novel approach to improve language functions in aphasia. fMRI revealed neural facilitation specifically during motor speech trials, which may have reduced switching costs between the overlapping neural systems for lexical retrieval and speech processing, thereby resulting in improved

  7. Functional connectivity of primary motor cortex is dependent on genetic burden in prodromal Huntington disease.

    Science.gov (United States)

    Koenig, Katherine A; Lowe, Mark J; Harrington, Deborah L; Lin, Jian; Durgerian, Sally; Mourany, Lyla; Paulsen, Jane S; Rao, Stephen M

    2014-09-01

    Subtle changes in motor function have been observed in individuals with prodromal Huntington disease (prHD), but the underlying neural mechanisms are not well understood nor is the cumulative effect of the disease (disease burden) on functional connectivity. The present study examined the resting-state functional magnetic resonance imaging (rs-fMRI) connectivity of the primary motor cortex (M1) in 16 gene-negative (NEG) controls and 48 gene-positive prHD participants with various levels of disease burden. The results showed that the strength of the left M1 connectivity with the ipsilateral M1 and somatosensory areas decreased as disease burden increased and correlated with motor symptoms. Weakened M1 connectivity within the motor areas was also associated with abnormalities in long-range connections that evolved with disease burden. In this study, M1 connectivity was decreased with visual centers (bilateral cuneus), but increased with a hub of the default mode network (DMN; posterior cingulate cortex). Changes in connectivity measures were associated with worse performance on measures of cognitive-motor functioning. Short- and long-range functional connectivity disturbances were also associated with volume loss in the basal ganglia, suggesting that weakened M1 connectivity is partly a manifestation of striatal atrophy. Altogether, the results indicate that the prodromal phase of HD is associated with abnormal interhemispheric interactions among motor areas and disturbances in the connectivity of M1 with visual centers and the DMN. These changes may, respectively, contribute to increased motor symptoms, visuomotor integration problems, and deficits in the executive control of movement as individuals approach a manifest diagnosis.

  8. Primary Motor Cortex Representation of Handgrip Muscles in Patients with Leprosy

    Science.gov (United States)

    Rangel, Maria Luíza Sales; Sanchez, Tiago Arruda; Moreira, Filipe Azaline; Hoefle, Sebastian; Souto, Inaiacy Bittencourt; da Cunha, Antônio José Ledo Alves

    2015-01-01

    Background Leprosy is an endemic infectious disease caused by Mycobacterium leprae that predominantly attacks the skin and peripheral nerves, leading to progressive impairment of motor, sensory and autonomic function. Little is known about how this peripheral neuropathy affects corticospinal excitability of handgrip muscles. Our purpose was to explore the motor cortex organization after progressive peripheral nerve injury and upper-limb dysfunction induced by leprosy using noninvasive transcranial magnetic stimulation (TMS). Methods In a cross-sectional study design, we mapped bilaterally in the primary motor cortex (M1) the representations of the hand flexor digitorum superficialis (FDS), as well as of the intrinsic hand muscles abductor pollicis brevis (APB), first dorsal interosseous (FDI) and abductor digiti minimi (ADM). All participants underwent clinical assessment, handgrip dynamometry and motor and sensory nerve conduction exams 30 days before mapping. Wilcoxon signed rank and Mann-Whitney tests were performed with an alpha-value of p<0.05. Findings Dynamometry performance of the patients’ most affected hand (MAH), was worse than that of the less affected hand (LAH) and of healthy controls participants (p = 0.031), confirming handgrip impairment. Motor threshold (MT) of the FDS muscle was higher in both hemispheres in patients as compared to controls, and lower in the hemisphere contralateral to the MAH when compared to that of the LAH. Moreover, motor evoked potential (MEP) amplitudes collected in the FDS of the MAH were higher in comparison to those of controls. Strikingly, MEPs in the intrinsic hand muscle FDI had lower amplitudes in the hemisphere contralateral to MAH as compared to those of the LAH and the control group. Taken together, these results are suggestive of a more robust representation of an extrinsic hand flexor and impaired intrinsic hand muscle function in the hemisphere contralateral to the MAH due to leprosy. Conclusion Decreased

  9. Plasticity Induced by Intermittent Theta Burst Stimulation in Bilateral Motor Cortices Is Not Altered in Older Adults.

    Science.gov (United States)

    Dickins, Daina S E; Sale, Martin V; Kamke, Marc R

    2015-01-01

    Numerous studies have reported that plasticity induced in the motor cortex by transcranial magnetic stimulation (TMS) is attenuated in older adults. Those investigations, however, have focused solely on the stimulated hemisphere. Compared to young adults, older adults exhibit more widespread activity across bilateral motor cortices during the performance of unilateral motor tasks, suggesting that the manifestation of plasticity might also be altered. To address this question, twenty young (65 years) underwent intermittent theta burst stimulation (iTBS) whilst attending to the hand targeted by the plasticity-inducing procedure. The amplitude of motor evoked potentials (MEPs) elicited by single pulse TMS was used to quantify cortical excitability before and after iTBS. Individual responses to iTBS were highly variable, with half the participants showing an unexpected decrease in cortical excitability. Contrary to predictions, however, there were no age-related differences in the magnitude or manifestation of plasticity across bilateral motor cortices. The findings suggest that advancing age does not influence the capacity for, or manifestation of, plasticity induced by iTBS.

  10. Plasticity Induced by Intermittent Theta Burst Stimulation in Bilateral Motor Cortices Is Not Altered in Older Adults

    Directory of Open Access Journals (Sweden)

    Daina S. E. Dickins

    2015-01-01

    Full Text Available Numerous studies have reported that plasticity induced in the motor cortex by transcranial magnetic stimulation (TMS is attenuated in older adults. Those investigations, however, have focused solely on the stimulated hemisphere. Compared to young adults, older adults exhibit more widespread activity across bilateral motor cortices during the performance of unilateral motor tasks, suggesting that the manifestation of plasticity might also be altered. To address this question, twenty young (65 years underwent intermittent theta burst stimulation (iTBS whilst attending to the hand targeted by the plasticity-inducing procedure. The amplitude of motor evoked potentials (MEPs elicited by single pulse TMS was used to quantify cortical excitability before and after iTBS. Individual responses to iTBS were highly variable, with half the participants showing an unexpected decrease in cortical excitability. Contrary to predictions, however, there were no age-related differences in the magnitude or manifestation of plasticity across bilateral motor cortices. The findings suggest that advancing age does not influence the capacity for, or manifestation of, plasticity induced by iTBS.

  11. A systematic review of non-motor rTMS induced motor cortex plasticity.

    Science.gov (United States)

    Nordmann, Grégory; Azorina, Valeriya; Langguth, Berthold; Schecklmann, Martin

    2015-01-01

    Motor cortex excitability can be measured by single- and paired-pulse transcranial magnetic stimulation (TMS). Repetitive transcranial magnetic stimulation (rTMS) can induce neuroplastic effects in stimulated and in functionally connected cortical regions. Due to its ability to non-invasively modulate cortical activity, rTMS has been investigated for the treatment of various neurological and psychiatric disorders. However, such studies revealed a high variability of both clinical and neuronal effects induced by rTMS. In order to better elucidate this meta-plasticity, rTMS-induced changes in motor cortex excitability have been monitored in various studies in a pre-post stimulation design. Here, we give a literature review of studies investigating motor cortex excitability changes as a neuronal marker for rTMS effects over non-motor cortical areas. A systematic literature review in April 2014 resulted in 29 articles in which motor cortex excitability was assessed before and after rTMS over non-motor areas. The majority of the studies focused on the stimulation of one of three separate cortical areas: the prefrontal area (17 studies), the cerebellum (8 studies), or the temporal cortex (3 studies). One study assessed the effects of multi-site rTMS. Most studies investigated healthy controls but some also stimulated patients with neuropsychiatric conditions (e.g., affective disorders, tinnitus). Methods and findings of the identified studies were highly variable showing no clear systematic pattern of interaction of non-motor rTMS with measures of motor cortex excitability. Based on the available literature, the measurement of motor cortex excitability changes before and after non-motor rTMS has only limited value in the investigation of rTMS related meta-plasticity as a neuronal state or as a trait marker for neuropsychiatric diseases. Our results do not suggest that there are systematic alterations of cortical excitability changes during rTMS treatment, which calls

  12. A systematic review of non-motor rTMS induced motor cortex plasticity

    Science.gov (United States)

    Nordmann, Grégory; Azorina, Valeriya; Langguth, Berthold; Schecklmann, Martin

    2015-01-01

    Motor cortex excitability can be measured by single- and paired-pulse transcranial magnetic stimulation (TMS). Repetitive transcranial magnetic stimulation (rTMS) can induce neuroplastic effects in stimulated and in functionally connected cortical regions. Due to its ability to non-invasively modulate cortical activity, rTMS has been investigated for the treatment of various neurological and psychiatric disorders. However, such studies revealed a high variability of both clinical and neuronal effects induced by rTMS. In order to better elucidate this meta-plasticity, rTMS-induced changes in motor cortex excitability have been monitored in various studies in a pre-post stimulation design. Here, we give a literature review of studies investigating motor cortex excitability changes as a neuronal marker for rTMS effects over non-motor cortical areas. A systematic literature review in April 2014 resulted in 29 articles in which motor cortex excitability was assessed before and after rTMS over non-motor areas. The majority of the studies focused on the stimulation of one of three separate cortical areas: the prefrontal area (17 studies), the cerebellum (8 studies), or the temporal cortex (3 studies). One study assessed the effects of multi-site rTMS. Most studies investigated healthy controls but some also stimulated patients with neuropsychiatric conditions (e.g., affective disorders, tinnitus). Methods and findings of the identified studies were highly variable showing no clear systematic pattern of interaction of non-motor rTMS with measures of motor cortex excitability. Based on the available literature, the measurement of motor cortex excitability changes before and after non-motor rTMS has only limited value in the investigation of rTMS related meta-plasticity as a neuronal state or as a trait marker for neuropsychiatric diseases. Our results do not suggest that there are systematic alterations of cortical excitability changes during rTMS treatment, which calls

  13. Shaping motor cortex plasticity through proprioception.

    Science.gov (United States)

    Avanzino, Laura; Pelosin, Elisa; Abbruzzese, Giovanni; Bassolino, Michela; Pozzo, Thierry; Bove, Marco

    2014-10-01

    Short-term upper limb disuse induces a hemispheric unbalance between the primary motor cortices (M1s). However, it is still unclear whether these changes are mainly attributable to the absence of voluntary movements or to the reduction of proprioceptive information. The goal of this work was to investigate the role of proprioception in modulating hemispheric balance during a short-term right arm immobilization. We evaluated the 2 M1s excitability and the interhemispheric inhibition (IHI) between M1s in 3 groups of healthy subjects. Two groups received during the immobilization a proprioceptive (P-VIB, 80 Hz) and tactile (T-VIB, 30 Hz) vibration to the right hand, respectively. Another group did not receive any conditioning sensory inputs (No-VIB). We found that in the No-VIB and in the T-VIB groups immobilization induced a decrease of left M1 excitability and IHI from left to right hemisphere and an increase of right M1 excitability and IHI from right to left hemisphere. Differently, only a partial decrease in left M1 excitability, no change in right M1 excitability and in IHI was observed in the P-VIB group. Our findings demonstrate that the maintenance of dynamic proprioceptive inputs in an immobilized arm through muscle vibration can prevent the hemispheric unbalance induced by short-term limb disuse.

  14. Dorsal anterior cingulate cortex modulates supplementary motor area in coordinated unimanual motor behavior

    OpenAIRE

    Asemi, Avisa; Ramaseshan, Karthik; Burgess, Ashley; Diwadkar, Vaibhav A.; Steven L Bressler

    2015-01-01

    Motor control is integral to all types of human behavior, and the dorsal Anterior Cingulate Cortex (dACC) is thought to play an important role in the brain network underlying motor control. Yet the role of the dACC in motor control is under-characterized. Here we aimed to characterize the dACC’s role in adolescent brain network interactions during a simple motor control task involving visually coordinated unimanual finger movements. Network interactions were assessed using both undirected and...

  15. Functional reorganization of motor and limbic circuits after exercise training in a rat model of bilateral parkinsonism.

    Directory of Open Access Journals (Sweden)

    Zhuo Wang

    Full Text Available Exercise training is widely used for neurorehabilitation of Parkinson's disease (PD. However, little is known about the functional reorganization of the injured brain after long-term aerobic exercise. We examined the effects of 4 weeks of forced running wheel exercise in a rat model of dopaminergic deafferentation (bilateral, dorsal striatal 6-hydroxydopamine lesions. One week after training, cerebral perfusion was mapped during treadmill walking or at rest using [(14C]-iodoantipyrine autoradiography. Regional cerebral blood flow-related tissue radioactivity (rCBF was analyzed in three-dimensionally reconstructed brains by statistical parametric mapping. In non-exercised rats, lesions resulted in persistent motor deficits. Compared to sham-lesioned rats, lesioned rats showed altered functional brain activation during walking, including: 1. hypoactivation of the striatum and motor cortex; 2. hyperactivation of non-lesioned areas in the basal ganglia-thalamocortical circuit; 3. functional recruitment of the red nucleus, superior colliculus and somatosensory cortex; 4. hyperactivation of the ventrolateral thalamus, cerebellar vermis and deep nuclei, suggesting recruitment of the cerebellar-thalamocortical circuit; 5. hyperactivation of limbic areas (amygdala, hippocampus, ventral striatum, septum, raphe, insula. These findings show remarkable similarities to imaging findings reported in PD patients. Exercise progressively improved motor deficits in lesioned rats, while increasing activation in dorsal striatum and rostral secondary motor cortex, attenuating a hyperemia of the zona incerta and eliciting a functional reorganization of regions participating in the cerebellar-thalamocortical circuit. Both lesions and exercise increased activation in mesolimbic areas (amygdala, hippocampus, ventral striatum, laterodorsal tegmental n., ventral pallidum, as well as in related paralimbic regions (septum, raphe, insula. Exercise, but not lesioning, resulted

  16. Movement Initiation Signals in Mouse Whisker Motor Cortex.

    Science.gov (United States)

    Sreenivasan, Varun; Esmaeili, Vahid; Kiritani, Taro; Galan, Katia; Crochet, Sylvain; Petersen, Carl C H

    2016-12-21

    Frontal cortex plays a central role in the control of voluntary movements, which are typically guided by sensory input. Here, we investigate the function of mouse whisker primary motor cortex (wM1), a frontal region defined by dense innervation from whisker primary somatosensory cortex (wS1). Optogenetic stimulation of wM1 evokes rhythmic whisker protraction (whisking), whereas optogenetic inactivation of wM1 suppresses initiation of whisking. Whole-cell membrane potential recordings and silicon probe recordings of action potentials reveal layer-specific neuronal activity in wM1 at movement initiation, and encoding of fast and slow parameters of movements during whisking. Interestingly, optogenetic inactivation of wS1 caused hyperpolarization and reduced firing in wM1, together with reduced whisking. Optogenetic stimulation of wS1 drove activity in wM1 with complex dynamics, as well as evoking long-latency, wM1-dependent whisking. Our results advance understanding of a well-defined frontal region and point to an important role for sensory input in controlling motor cortex. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  17. Body Topography Parcellates Human Sensory and Motor Cortex.

    Science.gov (United States)

    Kuehn, Esther; Dinse, Juliane; Jakobsen, Estrid; Long, Xiangyu; Schäfer, Andreas; Bazin, Pierre-Louis; Villringer, Arno; Sereno, Martin I; Margulies, Daniel S

    2017-07-01

    The cytoarchitectonic map as proposed by Brodmann currently dominates models of human sensorimotor cortical structure, function, and plasticity. According to this model, primary motor cortex, area 4, and primary somatosensory cortex, area 3b, are homogenous areas, with the major division lying between the two. Accumulating empirical and theoretical evidence, however, has begun to question the validity of the Brodmann map for various cortical areas. Here, we combined in vivo cortical myelin mapping with functional connectivity analyses and topographic mapping techniques to reassess the validity of the Brodmann map in human primary sensorimotor cortex. We provide empirical evidence that area 4 and area 3b are not homogenous, but are subdivided into distinct cortical fields, each representing a major body part (the hand and the face). Myelin reductions at the hand-face borders are cortical layer-specific, and coincide with intrinsic functional connectivity borders as defined using large-scale resting state analyses. Our data extend the Brodmann model in human sensorimotor cortex and suggest that body parts are an important organizing principle, similar to the distinction between sensory and motor processing. © The Author 2017. Published by Oxford University Press.

  18. Musical groove modulates motor cortex excitability: a TMS investigation.

    Science.gov (United States)

    Stupacher, Jan; Hove, Michael J; Novembre, Giacomo; Schütz-Bosbach, Simone; Keller, Peter E

    2013-07-01

    Groove is often described as a musical quality that can induce movement in a listener. This study examines the effects of listening to groove music on corticospinal excitability. Musicians and non-musicians listened to high-groove music, low-groove music, and spectrally matched noise, while receiving single-pulse transcranial magnetic stimulation (TMS) over the primary motor cortex either on-beat or off-beat. We examined changes in the amplitude of the motor-evoked potentials (MEPs), recorded from hand and arm muscles, as an index of activity within the motor system. Musicians and non-musicians rated groove similarly. MEP results showed that high-groove music modulated corticospinal excitability, whereas no difference occurred between low-groove music and noise. More specifically, musicians' MEPs were larger with high-groove than low-groove music, and this effect was especially pronounced for on-beat compared to off-beat pulses. These results indicate that high-groove music increasingly engages the motor system, and the temporal modulation of corticospinal excitability with the beat could stem from tight auditory-motor links in musicians. Conversely, non-musicians' MEPs were smaller for high-groove than low-groove music, and there was no effect of on- versus off-beat pulses, potentially stemming from suppression of overt movement. In sum, high-groove music engages the motor system, and previous training modulates how listening to music with a strong groove activates the motor system.

  19. Functional Plasticity in Somatosensory Cortex Supports Motor Learning by Observing.

    Science.gov (United States)

    McGregor, Heather R; Cashaback, Joshua G A; Gribble, Paul L

    2016-04-04

    An influential idea in neuroscience is that the sensory-motor system is activated when observing the actions of others [1, 2]. This idea has recently been extended to motor learning, in which observation results in sensory-motor plasticity and behavioral changes in both motor and somatosensory domains [3-9]. However, it is unclear how the brain maps visual information onto motor circuits for learning. Here we test the idea that the somatosensory system, and specifically primary somatosensory cortex (S1), plays a role in motor learning by observing. In experiment 1, we applied stimulation to the median nerve to occupy the somatosensory system with unrelated inputs while participants observed a tutor learning to reach in a force field. Stimulation disrupted motor learning by observing in a limb-specific manner. Stimulation delivered to the right arm (the same arm used by the tutor) disrupted learning, whereas left arm stimulation did not. This is consistent with the idea that a somatosensory representation of the observed effector must be available during observation for learning to occur. In experiment 2, we assessed S1 cortical processing before and after observation by measuring somatosensory evoked potentials (SEPs) associated with median nerve stimulation. SEP amplitudes increased only for participants who observed learning. Moreover, SEPs increased more for participants who exhibited greater motor learning following observation. Taken together, these findings support the idea that motor learning by observing relies on functional plasticity in S1. We propose that visual signals about the movements of others are mapped onto motor circuits for learning via the somatosensory system.

  20. Cerebellum to motor cortex paired associative stimulation induces bidirectional STDP-like plasticity in human motor cortex.

    Science.gov (United States)

    Lu, Ming-Kuei; Tsai, Chon-Haw; Ziemann, Ulf

    2012-01-01

    The cerebellum is crucially important for motor control and adaptation. Recent non-invasive brain stimulation studies have indicated the possibility to alter the excitability of the cerebellum and its projections to the contralateral motor cortex, with behavioral consequences on motor control and adaptation. Here we sought to induce bidirectional spike-timing dependent plasticity (STDP)-like modifications of motor cortex (M1) excitability by application of paired associative stimulation (PAS) in healthy subjects. Conditioning stimulation over the right lateral cerebellum (CB) preceded focal transcranial magnetic stimulation (TMS) of the left M1 hand area at an interstimulus interval of 2 ms (CB→M1 PAS(2 ms)), 6 ms (CB→M1 PAS(6 ms)) or 10 ms (CB→M1 PAS(10 ms)) or randomly alternating intervals of 2 and 10 ms (CB→M1 PAS(Control)). Effects of PAS on M1 excitability were assessed by the motor-evoked potential (MEP) amplitude, short-interval intracortical inhibition (SICI), intracortical facilitation (ICF) and cerebellar-motor cortex inhibition (CBI) in the first dorsal interosseous muscle of the right hand. CB→M1 PAS(2 ms) resulted in MEP potentiation, CB→M1 PAS(6 ms) and CB→M1 PAS(10 ms) in MEP depression, and CB→M1 PAS(Control) in no change. The MEP changes lasted for 30-60 min after PAS. SICI and CBI decreased non-specifically after all PAS protocols, while ICF remained unaltered. The physiological mechanisms underlying these MEP changes are carefully discussed. Findings support the notion of bidirectional STDP-like plasticity in M1 mediated by associative stimulation of the cerebello-dentato-thalamo-cortical pathway and M1. Future studies may investigate the behavioral significance of this plasticity.

  1. Simultaneous high-definition transcranial direct current stimulation of the motor cortex and motor imagery.

    Science.gov (United States)

    Baxter, Bryan S; Edelman, Bradley; Zhang, Xiaotong; Roy, Abhrajeet; He, Bin

    2014-01-01

    Transcranial direct current stimulation (tDCS) has been used to affect the excitability of neurons within the cerebral cortex. Improvements in motor learning have been found in multiple studies when tDCS was applied to the motor cortex during or before task learning is performed. The application of tDCS to motor imagery, a cognitive task showing activation in similar areas to motor execution, has resulted in differing effects based on the amplitude and duration of stimulation. We utilize high definition tDCS, a more spatially localized version of tDCS, to investigate the effect of anodal stimulation on human motor imagery performance. In parallel, we model this stimulation using a finite element model to calculate stimulation area and electrical field amplitude within the brain in the motor cortex and non-stimulated frontal and parietal regions. Overall, we found a delayed increase in resting baseline power 30 minutes post stimulation in both the right and left sensorimotor cortices which resulted in an increase in event-related desynchronization.

  2. Increased motor cortex excitability during motor imagery in brain-computer interface trained subjects

    Directory of Open Access Journals (Sweden)

    Olesya eMokienko

    2013-11-01

    Full Text Available Background: Motor imagery (MI is the mental performance of movement without muscle activity. It is generally accepted that MI and motor performance have similar physiological mechanisms.Purpose: To investigate the activity and excitability of cortical motor areas during MI in subjects who were previously trained with an MI-based brain-computer interface (BCI.Subjects and methods: Eleven healthy volunteers without neurological impairments (mean age, 36 years; range: 24–68 years were either trained with an MI-based BCI (BCI-trained, n = 5 or received no BCI training (n = 6, controls. Subjects imagined grasping in a blocked paradigm task with alternating rest and task periods. For evaluating the activity and excitability of cortical motor areas we used functional MRI and navigated transcranial magnetic stimulation (nTMS.Results: fMRI revealed activation in Brodmann areas 3 and 6, the cerebellum, and the thalamus during MI in all subjects. The primary motor cortex was activated only in BCI-trained subjects. The associative zones of activation were larger in non-trained subjects. During MI, motor evoked potentials recorded from two of the three targeted muscles were significantly higher only in BCI-trained subjects. The motor threshold decreased (median = 17% during MI, which was also observed only in BCI-trained subjects.Conclusion: Previous BCI training increased motor cortex excitability during MI. These data may help to improve BCI applications, including rehabilitation of patients with cerebral palsy.

  3. Transformation of Cortex-wide Emergent Properties during Motor Learning.

    Science.gov (United States)

    Makino, Hiroshi; Ren, Chi; Liu, Haixin; Kim, An Na; Kondapaneni, Neehar; Liu, Xin; Kuzum, Duygu; Komiyama, Takaki

    2017-05-17

    Learning involves a transformation of brain-wide operation dynamics. However, our understanding of learning-related changes in macroscopic dynamics is limited. Here, we monitored cortex-wide activity of the mouse brain using wide-field calcium imaging while the mouse learned a motor task over weeks. Over learning, the sequential activity across cortical modules became temporally more compressed, and its trial-by-trial variability decreased. Moreover, a new flow of activity emerged during learning, originating from premotor cortex (M2), and M2 became predictive of the activity of many other modules. Inactivation experiments showed that M2 is critical for the post-learning dynamics in the cortex-wide activity. Furthermore, two-photon calcium imaging revealed that M2 ensemble activity also showed earlier activity onset and reduced variability with learning, which was accompanied by changes in the activity-movement relationship. These results reveal newly emergent properties of macroscopic cortical dynamics during motor learning and highlight the importance of M2 in controlling learned movements. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Motor cortex electrical stimulation augments sprouting of the corticospinal tract and promotes recovery of motor function.

    Science.gov (United States)

    Carmel, Jason B; Martin, John H

    2014-01-01

    The corticospinal system-with its direct spinal pathway, the corticospinal tract (CST) - is the primary system for controlling voluntary movement. Our approach to CST repair after injury in mature animals was informed by our finding that activity drives establishment of connections with spinal cord circuits during postnatal development. After incomplete injury in maturity, spared CST circuits sprout, and partially restore lost function. Our approach harnesses activity to augment this injury-dependent CST sprouting and to promote function. Lesion of the medullary pyramid unilaterally eliminates all CST axons from one hemisphere and allows examination of CST sprouting from the unaffected hemisphere. We discovered that 10 days of electrical stimulation of either the spared CST or motor cortex induces CST axon sprouting that partially reconstructs the lost CST. Stimulation also leads to sprouting of the cortical projection to the magnocellular red nucleus, where the rubrospinal tract originates. Coordinated outgrowth of the CST and cortical projections to the red nucleus could support partial re-establishment of motor systems connections to the denervated spinal motor circuits. Stimulation restores skilled motor function in our animal model. Lesioned animals have a persistent forelimb deficit contralateral to pyramidotomy in the horizontal ladder task. Rats that received motor cortex stimulation either after acute or chronic injury showed a significant functional improvement that brought error rate to pre-lesion control levels. Reversible inactivation of the stimulated motor cortex reinstated the impairment demonstrating the importance of the stimulated system to recovery. Motor cortex electrical stimulation is an effective approach to promote spouting of spared CST axons. By optimizing activity-dependent sprouting in animals, we could have an approach that can be translated to the human for evaluation with minimal delay.

  5. Motor cortex electrical stimulation augments sprouting of the corticospinal tract and promotes recovery of motor function

    Directory of Open Access Journals (Sweden)

    Jason B Carmel

    2014-06-01

    Full Text Available The corticospinal system—with its direct spinal pathway, the corticospinal tract (CST—is the primary system for controlling voluntary movement. Our approach to CST repair after injury in mature animals was informed by our finding that activity drives establishment of connections with spinal cord circuits during postnatal development. After incomplete injury in maturity, spared CST circuits sprout and partially restore lost function. Our approach harnesses activity to augment this injury-dependent CST sprouting and to promote function. Lesion of the medullary pyramid unilaterally eliminates all CST axons from one hemisphere and allows examination of CST sprouting from the unaffected hemisphere. We discovered that ten days of electrical stimulation of either the spared CST or motor cortex induces CST axon sprouting that partially reconstructs the lost CST. Stimulation also leads to sprouting of the cortical projection to the magnocellular red nucleus, where the rubrospinal tract originates. Coordinated outgrowth of the CST and cortical projections to the red nucleus could support partial re-establishment of motor systems connections to the denervated spinal motor circuits. Stimulation restores skilled motor function in our animal model. Lesioned animals have a persistent forelimb deficit contralateral to pyramidotomy in the horizontal ladder task. Rats that received motor cortex stimulation either after acute or chronic injury showed a significant functional improvement that brought error rate to pre-lesion control levels. Reversible inactivation of the stimulated motor cortex reinstated the impairment demonstrating the importance of the stimulated system to recovery. Motor cortex electrical stimulation is an effective approach to promote spouting of spared CST axons. By optimizing activity-dependent sprouting in animals, we could have an approach that can be translated to the human for evaluation with minimal delay.

  6. Role of motor cortex NMDA receptors in learning-dependent synaptic plasticity of behaving mice

    OpenAIRE

    Mazahir T Hasan; Hernández-González, Samuel; Dogbevia, Godwin; Treviño, Mario; Bertocchi, Ilaria; Gruart, Agnès; Delgado-García, José M.

    2013-01-01

    The primary motor cortex has an important role in the precise execution of learned motor responses. During motor learning, synaptic efficacy between sensory and primary motor cortical neurons is enhanced, possibly involving long-term potentiation and N-methyl-D-aspartate (NMDA)-specific glutamate receptor function. To investigate whether NMDA receptor in the primary motor cortex can act as a coincidence detector for activity-dependent changes in synaptic strength and associative learning, her...

  7. Modulation of the motor cortex during singing-voice perception.

    Science.gov (United States)

    Lévêque, Yohana; Schön, Daniele

    2015-04-01

    Several studies on action observation have shown that the biological dimension of movement modulates sensorimotor interactions in perception. In the present fMRI study, we tested the hypothesis that the biological dimension of sound modulates the involvement of the motor system in human auditory perception, using musical tasks. We first localized the vocal motor cortex in each participant. Then we compared the BOLD response to vocal, semi-vocal and non-vocal melody perception, and found greater activity for voice perception in the right sensorimotor cortex. We additionally ran a psychophysiological interaction analysis with the right sensorimotor as a seed, showing that the vocal dimension of the stimuli enhanced the connectivity between the seed region and other important nodes of the auditory dorsal stream. Finally, the participants' vocal ability was negatively correlated to the voice effect in the Inferior Parietal Lobule. These results suggest that the biological dimension of singing-voice impacts the activity within the auditory dorsal stream, probably via a facilitated matching between the perceived sound and the participant motor representations. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Representation of individual forelimb muscles in primary motor cortex.

    Science.gov (United States)

    Hudson, Heather M; Park, Michael C; Belhaj-Saïf, Abderraouf; Cheney, Paul D

    2017-07-01

    Stimulus-triggered averaging (StTA) of forelimb muscle electromyographic (EMG) activity was used to investigate individual forelimb muscle representation within the primary motor cortex (M1) of rhesus macaques with the objective of determining the extent of intra-areal somatotopic organization. Two monkeys were trained to perform a reach-to-grasp task requiring multijoint coordination of the forelimb. EMG activity was simultaneously recorded from 24 forelimb muscles including 5 shoulder, 7 elbow, 5 wrist, 5 digit, and 2 intrinsic hand muscles. Microstimulation (15 µA at 15 Hz) was delivered throughout the movement task and individual stimuli were used as triggers for generating StTAs of EMG activity. StTAs were used to map the cortical representations of individual forelimb muscles. As reported previously (Park et al. 2001), cortical maps revealed a central core of distal muscle (wrist, digit, and intrinsic hand) representation surrounded by a horseshoe-shaped proximal (shoulder and elbow) muscle representation. In the present study, we found that shoulder and elbow flexor muscles were predominantly represented in the lateral branch of the horseshoe whereas extensors were predominantly represented in the medial branch. Distal muscles were represented within the core distal forelimb representation and showed extensive overlap. For the first time, we also show maps of inhibitory output from motor cortex, which follow many of the same organizational features as the maps of excitatory output.NEW & NOTEWORTHY While the orderly representation of major body parts along the precentral gyrus has been known for decades, questions have been raised about the possible existence of additional more detailed aspects of somatotopy. In this study, we have investigated this question with respect to muscles of the arm and show consistent features of within-arm (intra-areal) somatotopic organization. For the first time we also show maps of how inhibitory output from motor cortex is

  9. Response of SII cortex to ipsilateral, contralateral and bilateral flutter stimulation in the cat

    Directory of Open Access Journals (Sweden)

    Favorov Oleg

    2005-02-01

    Full Text Available Abstract Background A distinctive property of SII is that it is the first cortical stage of the somatosensory projection pathway that integrates information arising from both sides of the body. However, there is very little known about how inputs across the body mid-line are processed within SII. Results Optical intrinsic signal imaging was used to evaluate the response of primary somatosensory cortex (SI and SII in the same hemisphere to 25 Hz sinusoidal vertical skin displacement stimulation ("skin flutter" applied contralaterally, ipsilaterally, and bilaterally to the central pads of the forepaws. A localized increase in absorbance in both SI and SII was evoked by both contralateral and bilateral flutter stimulation. Ipsilateral flutter stimulation evoked a localized increase in absorbance in SII, but not in SI. The SII region that responded with an increase in absorbance to ipsilateral stimulation was posterior to the region in which absorbance increased maximally in response to stimulation of the contralateral central pad. Additionally, in the posterior SII region that responded maximally to ipsilateral stimulation of the central pad, bilateral central pad stimulation approximated a linear summation of the SII responses to independent stimulation of the contralateral and ipsilateral central pads. Conversely, in anterior SII (the region that responded maximally to contralateral stimulation, bilateral stimulation was consistently less than the response evoked from the contralateral central pad. Conclusions The results indicate that two regions located at neighboring, but distinctly different A-P levels of the anterior ectosylvian gyrus process input from opposite sides of the body midline in very different ways. The results suggest that the SII cortex, in the cat, can be subdivided into at least two functionally distinct regions and that these functionally distinct regions demonstrate a laterality preference within SII.

  10. Motor function in a patient with bilateral lesions of the globus pallidus

    NARCIS (Netherlands)

    Haaxma, R; vanBoxtel, A; Brouwer, WH; Goeken, LNH; vanderGon, JJD; Colebatch, JG; Martin, A; Brooks, DJ; Noth, J; Marsden, CD

    1995-01-01

    This study describes the long-term motor deficits of a patient who, after a toxic encephalopathy, sustained extensive bilateral damage to both segments of the globus pallidus (GP) and the right substantia nigra (SN). There were no signs of lesions of the pyramidal tracts or of other motor

  11. Motor function in a patient with bilateral lesions of the globus pallidus

    NARCIS (Netherlands)

    Haaxma, R; vanBoxtel, A; Brouwer, WH; Goeken, LNH; vanderGon, JJD; Colebatch, JG; Martin, A; Brooks, DJ; Noth, J; Marsden, CD

    1995-01-01

    This study describes the long-term motor deficits of a patient who, after a toxic encephalopathy, sustained extensive bilateral damage to both segments of the globus pallidus (GP) and the right substantia nigra (SN). There were no signs of lesions of the pyramidal tracts or of other motor structures

  12. Skilled Bimanual Training Drives Motor Cortex Plasticity in Children With Unilateral Cerebral Palsy.

    Science.gov (United States)

    Friel, Kathleen M; Kuo, Hsing-Ching; Fuller, Jason; Ferre, Claudio L; Brandão, Marina; Carmel, Jason B; Bleyenheuft, Yannick; Gowatsky, Jaimie L; Stanford, Arielle D; Rowny, Stefan B; Luber, Bruce; Bassi, Bruce; Murphy, David L K; Lisanby, Sarah H; Gordon, Andrew M

    2016-10-01

    Background Intensive bimanual therapy can improve hand function in children with unilateral spastic cerebral palsy (USCP). We compared the effects of structured bimanual skill training versus unstructured bimanual practice on motor outcomes and motor map plasticity in children with USCP. Objective We hypothesized that structured skill training would produce greater motor map plasticity than unstructured practice. Methods Twenty children with USCP (average age 9.5; 12 males) received therapy in a day camp setting, 6 h/day, 5 days/week, for 3 weeks. In structured skill training (n = 10), children performed progressively more difficult movements and practiced functional goals. In unstructured practice (n = 10), children engaged in bimanual activities but did not practice skillful movements or functional goals. We used the Assisting Hand Assessment (AHA), Jebsen-Taylor Test of Hand Function (JTTHF), and Canadian Occupational Performance Measure (COPM) to measure hand function. We used single-pulse transcranial magnetic stimulation to map the representation of first dorsal interosseous and flexor carpi radialis muscles bilaterally. Results Both groups showed significant improvements in bimanual hand use (AHA; P < .05) and hand dexterity (JTTHF; P < .001). However, only the structured skill group showed increases in the size of the affected hand motor map and amplitudes of motor evoked potentials (P < .01). Most children who showed the most functional improvements (COPM) had the largest changes in map size. Conclusions These findings uncover a dichotomy of plasticity: the unstructured practice group improved hand function but did not show changes in motor maps. Skill training is important for driving motor cortex plasticity in children with USCP.

  13. Dorsal anterior cingulate cortex modulates supplementary motor area in coordinated unimanual motor behavior

    Directory of Open Access Journals (Sweden)

    Avisa eAsemi

    2015-06-01

    Full Text Available Motor control is integral to all types of human behavior, and the dorsal Anterior Cingulate Cortex (dACC is thought to play an important role in the brain network underlying motor control. Yet the role of the dACC in motor control is under-characterized. Here we aimed to characterize the dACC’s role in adolescent brain network interactions during a simple motor control task involving visually coordinated unimanual finger movements. Network interactions were assessed using both undirected and directed functional connectivity analysis of fMRI BOLD signals, comparing the task with a rest condition. The relation between the dACC and Supplementary Motor Area (SMA was compared to that between the dACC and Primary Motor Cortex (M1. The directed signal from dACC to SMA was significantly elevated during motor control in the task. By contrast, the directed signal from SMA to dACC, both directed signals between dACC and M1, and the undirected functional connections of dACC with SMA and M1, all did not differ between task and rest. Undirected coupling of dACC with both SMA and dACC, and only the dACC-to-SMA directed signal, were significantly greater for a proactive than a reactive task condition, suggesting that dACC plays a role in motor control by maintaining stimulus timing expectancy. Overall, these results suggest that the dACC selectively modulates the SMA during visually coordinated unimanual behavior in adolescence. The role of the dACC as an important brain area for the mediation of task-related motor control may be in place in adolescence, continuing into adulthood. The task and analytic approach described here should be extended to the study of healthy adults to examine network profiles of the dACC during basic motor behavior.

  14. Dorsal anterior cingulate cortex modulates supplementary motor area in coordinated unimanual motor behavior.

    Science.gov (United States)

    Asemi, Avisa; Ramaseshan, Karthik; Burgess, Ashley; Diwadkar, Vaibhav A; Bressler, Steven L

    2015-01-01

    Motor control is integral to all types of human behavior, and the dorsal Anterior Cingulate Cortex (dACC) is thought to play an important role in the brain network underlying motor control. Yet the role of the dACC in motor control is under-characterized. Here we aimed to characterize the dACC's role in adolescent brain network interactions during a simple motor control task involving visually coordinated unimanual finger movements. Network interactions were assessed using both undirected and directed functional connectivity analysis of functional Magnetic Resonance Imaging (fMRI) Blood-Oxygen-Level-Dependent (BOLD) signals, comparing the task with a rest condition. The relation between the dACC and Supplementary Motor Area (SMA) was compared to that between the dACC and Primary Motor Cortex (M1). The directed signal from dACC to SMA was significantly elevated during motor control in the task. By contrast, the directed signal from SMA to dACC, both directed signals between dACC and M1, and the undirected functional connections of dACC with SMA and M1, all did not differ between task and rest. Undirected coupling of dACC with both SMA and dACC, and only the dACC-to-SMA directed signal, were significantly greater for a proactive than a reactive task condition, suggesting that dACC plays a role in motor control by maintaining stimulus timing expectancy. Overall, these results suggest that the dACC selectively modulates the SMA during visually coordinated unimanual behavior in adolescence. The role of the dACC as an important brain area for the mediation of task-related motor control may be in place in adolescence, continuing into adulthood. The task and analytic approach described here should be extended to the study of healthy adults to examine network profiles of the dACC during basic motor behavior.

  15. Evaluation of the Cortical Silent Period of the Laryngeal Motor Cortex in Healthy Individuals

    Science.gov (United States)

    Chen, Mo; Summers, Rebekah L. S.; Goding, George S.; Samargia, Sharyl; Ludlow, Christy L.; Prudente, Cecília N.; Kimberley, Teresa J.

    2017-01-01

    Objective: This work aimed to evaluate the cortical silent period (cSP) of the laryngeal motor cortex (LMC) using the bilateral thyroarytenoid (TA) muscles with transcranial magnetic stimulation (TMS). Methods: In 11 healthy participants, fine-wire electromyography (EMG) was used to record bilateral TA muscle responses to single pulse TMS delivered to the LMC in both hemispheres. Peripheral responses to stimulation over the mastoid, where the vagus nerve exits the skull, were collected to verify the central origin of the cortical stimulation responses by comparing the latencies. Results: The cSP duration ranged from 41.7 to 66.4 ms. The peripherally evoked motor-evoked potential (MEP) peak occurred 5–9 ms earlier than the cortical responses (for both sides of TAs: p < 0.0001) with no silent period. The right TA MEP latencies were earlier than the left TA responses for both peripheral and cortical measures (p ≤ 0.0001). Conclusion: These findings demonstrate the feasibility of measuring cSP of LMC based on intrinsic laryngeal muscles responses during vocalization in healthy volunteers. Significance: The technique could be used to study the pathophysiology of neurological disorders that affect TA muscles, such as spasmodic dysphonia. Further, the methodology has application to other muscles of the head and neck not accessible using surface electrodes. PMID:28326007

  16. Induction of plasticity in the human motor cortex by pairing an auditory stimulus with TMS

    OpenAIRE

    Paul Fredrick Sowman; Jesper eRasmussen; Søren eDueholm; Natalie eMrachacz-Kersting

    2014-01-01

    Acoustic stimuli can cause a transient increase in the excitability of the motor cortex. The current study leverages this phenomenon to develop a method for testing the integrity of auditorimotor integration and the capacity for auditorimotor plasticity. We demonstrate that appropriately timed transcranial magnetic stimulation (TMS) of the hand area, paired with auditorily mediated excitation of the motor cortex, induces an enhancement of motor cortex excitability that lasts beyond the time o...

  17. Trains of transcranial direct current stimulation antagonize motor cortex hypoexcitability induced by acute hemicerebellectomy.

    Science.gov (United States)

    Ben Taib, Nordeyn Oulad; Manto, Mario

    2009-10-01

    The cerebellum is a key modulator of motor cortex activity, allowing both the maintenance and fine-tuning of motor cortex discharges. One elemental defect associated with acute cerebellar lesions is decreased excitability of the contralateral motor cortex, which is assumed to participate in deficits in skilled movements and considered a major defect in motor cortex properties. In the present study, the authors assessed the effect of trains of anodal transcranial direct current stimulation (tDCS), which elicits polarity-dependent shifts in resting membrane potentials. Transcranial DCS countered the defect in motor cortex excitability contralaterally to the hemicerebellar ablation. The depression of both the H-reflex and F wave remained unchanged with tDCS, and cutaneomuscular reflexes remained unaffected. Transcranial DCS antagonized motor cortex hypoexcitability induced by high-frequency stimulation of interpositus nucleus. The authors' results show that tDCS has the potential to modulate motor cortex excitability after acute cerebellar dysfunction. By putting the motor cortex at the appropriate level of excitability, tDCS might allow the motor cortex to become more reactive to the procedures of training or learning.

  18. Perirhinal cortex relays auditory information to the frontal motor cortices in the rat.

    Science.gov (United States)

    Kyuhou, Shin-ichi; Matsuzaki, Ryuichi; Gemba, Hisae

    2003-12-26

    Auditory evoked potentials (AEPs) were recorded in the motor cortices (MC) with chronically implanted electrodes in the rat. Some of the AEPs in the MC, namely negative potentials on the surface and positive ones at a depth of 2 mm at latencies of about 50-150 ms, were abolished by limited bilateral lesions of the anterior perirhinal cortex (PERa) which was responsive to auditory stimulus, indicating that the AEPs in the MC were at least partially relayed in the PERa. The auditory response in the MC was prominently enhanced when water was supplied or the medial forebrain bundle was stimulated after auditory stimulus. These results indicate that the MC receives the reward associated auditory information from the PERa.

  19. The changes of regional cerebral blood flow: successful pain relief of intractable CRPS type II patients by motor cortex stimulation

    Energy Technology Data Exchange (ETDEWEB)

    Jung, J. A.; Son, H. S.; Kim, S. H.; Jung, S. G [The Catholic University of Korea, Seoul (Korea, Republic of)

    2004-07-01

    Authors report the effectiveness of MCS in extraordinarily extended pain due to intractable CRPS type II and rCBF study result for mechanism of pain control by MCS. A 43-year-old male presented severe spontaneous burning pain in his left hand and forearm and allodynia over the left arm and left hemibody. Authors planned MCS as a neuromodulation therapy for this intractable peripheral neuropathic pain patient because further neurodestructive procedure did not work anymore and have a potential risk of further aggrevation of neuopathic pain. We performed baseline and stimulation brain perfusion SPECT using 20 mCi of Tc-99m ECD. The baseline CBD studies were done with stimulator 'off' state and stimulation studies were done after stimulator 'on' with satisfactory pain relief. For the stimulation study, the radioisotope was injected immediately after pain-relief and the images were taken about 50 minutes after injection of radioisotope. In resting rCBF in the patient was compared with normal control datas, we found significant increase in rCBF in the bilateral prefrontal cortex, right dorsolateral prefrontal cortex, right superior temporal gyrus, left temporooccipital area. When rCBF datas obtained after alleviation of pain with stimulator 'on' . there were significant increase in rCBF in bilateral prefrontal cortex and left temporoocipital area. After subtraction of ECD SPECT, we found significant increase in rCBF in the right premotor and supplementary motor cortex left sensorimotor cortex, right cingulated cortex, right posterior insular cortex, right anterior limb of internal capsule. left orbitofrontal cortex and right pyramidal tract in cerebral peduncle. Authors report exellent pain control by MCS in a case of severe CRPS type II with hemibody involvement and regional cerebral blood flow changes according to successful pain control.

  20. Augmenting Plasticity Induction in Human Motor Cortex by Disinhibition Stimulation.

    Science.gov (United States)

    Cash, Robin F H; Murakami, Takenobu; Chen, Robert; Thickbroom, Gary W; Ziemann, Ulf

    2016-01-01

    Cellular studies showed that disinhibition, evoked pharmacologically or by a suitably timed priming stimulus, can augment long-term plasticity (LTP) induction. We demonstrated previously that transcranial magnetic stimulation evokes a period of presumably GABA(B)ergic late cortical disinhibition (LCD) in human primary motor cortex (M1). Here, we hypothesized that, in keeping with cellular studies, LCD can augment LTP-like plasticity in humans. In Experiment 1, patterned repetitive TMS was applied to left M1, consisting of 6 trains (intertrain interval, 8 s) of 4 doublets (interpulse interval equal to individual peak I-wave facilitation, 1.3-1.5 ms) spaced by the individual peak LCD (interdoublet interval (IDI), 200-250 ms). This intervention (total of 48 pulses applied over ∼45 s) increased motor-evoked potential amplitude, a marker of corticospinal excitability, in a right hand muscle by 147% ± 4%. Control experiments showed that IDIs shorter or longer than LCD did not result in LTP-like plasticity. Experiment 2 indicated topographic specificity to the M1 hand region stimulated by TMS and duration of the LTP-like plasticity of 60 min. In conclusion, GABA(B)ergic LCD offers a powerful new approach for augmenting LTP-like plasticity induction in human cortex. We refer to this protocol as disinhibition stimulation (DIS).

  1. Psychogenic paralysis and recovery after motor cortex transcranial magnetic stimulation.

    Science.gov (United States)

    Chastan, Nathalie; Parain, Dominique

    2010-07-30

    Psychogenic paralysis presents a real treatment challenge. Despite psychotherapy, physiotherapy, antidepressants, acupuncture, or hypnosis, the outcome is not always satisfactory with persistent symptoms after long-term follow-up. We conducted a retrospective study to assess clinical features and to propose an alternative treatment based on repetitive transcranial magnetic stimulation (rTMS). Seventy patients (44 F/26 M, mean age: 24.7 +/- 16.6 years) experienced paraparesis (57%), monoparesis (37%), tetraparesis (3%), or hemiparesis (3%). A precipitating event was observed in 42 patients, primarily as a psychosocial event or a physical injury. An average of 30 stimuli over the motor cortex contralateral to the corresponding paralysis was delivered at low frequency with a circular coil. The rTMS was effective in 89% of cases, with a significantly better outcome for acute rather than chronic symptoms. In conclusion, motor cortex rTMS seem to be very effective in patients with psychogenic paralysis and could be considered a useful therapeutic option.

  2. Different motor learning effects on excitability changes of motor cortex in muscle contraction state.

    Science.gov (United States)

    Sugawara, Kenichi; Tanabe, Shigeo; Suzuki, Tomotaka; Higashi, Toshio

    2013-09-01

    We aimed to investigate whether motor learning induces different excitability changes in the human motor cortex (M1) between two different muscle contraction states (before voluntary contraction [static] or during voluntary contraction [dynamic]). For the same, using motor evoked potentials (MEPs) obtained by transcranial magnetic stimulation (TMS), we compared excitability changes during these two states after pinch-grip motor skill learning. The participants performed a force output tracking task by pinch grip on a computer screen. TMS was applied prior to the pinch grip (static) and after initiation of voluntary contraction (dynamic). MEPs of the following muscles were recorded: first dorsal interosseous (FDI), thenar muscle (Thenar), flexor carpi radialis (FCR), and extensor carpi radialis (ECR) muscles. During both the states, motor skill training led to significant improvement of motor performance. During the static state, MEPs of the FDI muscle were significantly facilitated after motor learning; however, during the dynamic state, MEPs of the FDI, Thenar, and FCR muscles were significantly decreased. Based on the results of this study, we concluded that excitability changes in the human M1 are differentially influenced during different voluntary contraction states (static and dynamic) after motor learning.

  3. The role of plastic changes in the motor cortex and spinal cord for motor learning

    DEFF Research Database (Denmark)

    Nielsen, Jens Bo; Lundbye-Jensen, Jesper

    2010-01-01

    Adaptive changes of the efficacy of neural circuitries at different sites of the central nervous system is the basis of acquisition of new motor skills. Non-invasive human imaging and electrophysiological experiments have demonstrated that the primary motor cortex and spinal cord circuitries...... are key players in the early stages of skill acquisition and consolidation of motor learning. Expansion of the cortical representation of the trained muscles, changes in corticomuscular coupling and changes in stretch reflex activity are thus all markers of neuroplastic changes accompanying early skill...... acquisition. We have shown in recent experiments that sensory feedback from the active muscles play a surprisingly specific role at this stage of learning. Following motor skill training, repeated activation of sensory afferents from the muscle that has been involved in a previous training session, interfered...

  4. Parietal operculum and motor cortex activities predict motor recovery in moderate to severe stroke

    Directory of Open Access Journals (Sweden)

    Firdaus Fabrice Hannanu

    2017-01-01

    In subacute stroke, fMRI brain activity related to passive movement measured in a sensorimotor network defined by activity during voluntary movement predicted motor recovery better than baseline motor-FMS alone. Furthermore, fMRI sensorimotor network activity measures considered alone allowed excellent clinical recovery prediction and may provide reliable biomarkers for assessing new therapies in clinical trial contexts. Our findings suggest that neural reorganization related to motor recovery from moderate to severe stroke results from balanced changes in ipsilesional MI (BA4a and a set of phylogenetically more archaic sensorimotor regions in the ventral sensorimotor trend, in which OP1 and OP4 processes may complement the ipsilesional dorsal motor cortex in achieving compensatory sensorimotor recovery.

  5. The role of plastic changes in the motor cortex and spinal cord for motor learning

    DEFF Research Database (Denmark)

    Nielsen, Jens Bo; Lundbye-Jensen, Jesper

    2010-01-01

    acquisition. We have shown in recent experiments that sensory feedback from the active muscles play a surprisingly specific role at this stage of learning. Following motor skill training, repeated activation of sensory afferents from the muscle that has been involved in a previous training session, interfered...... the consolidation of increased performance of a different previously trained task involving the same movement direction and muscle group, whereas training of other muscles had no effect. This emphasizes the role of specific sensory error signals in the acquisition of new motor skills and illustrates the functional......Adaptive changes of the efficacy of neural circuitries at different sites of the central nervous system is the basis of acquisition of new motor skills. Non-invasive human imaging and electrophysiological experiments have demonstrated that the primary motor cortex and spinal cord circuitries...

  6. Early bilateral sensory deprivation blocks the development of coincident discharge in rat barrel cortex.

    Science.gov (United States)

    Ghoshal, Ayan; Pouget, Pierre; Popescu, Maria; Ebner, Ford

    2009-02-25

    Several theories have proposed a functional role for synchronous neuronal firing in generating the neural code of a sensory perception. Synchronous neural activity develops during a critical postnatal period of cortical maturation, and severely reducing neural activity in a sensory pathway during this period could interfere with the development of coincident discharge among cortical neurons. Loss of such synchrony could provide a fundamental mechanism for the degradation of acuity shown in behavioral studies. We tested the hypothesis that synchronous discharge of barrel cortex neurons would fail to develop after sensory deprivation produced by bilateral whisker trimming from birth to postnatal day 60. By studying the correlated discharge of cortical neuron pairs, we found evidence for strong correlated firing in control animals, and this synchrony was almost absent among pairs of cortical barrel neurons in deprived animals. The degree of synchrony impairment was different in subregions of rat barrel cortex. The model that best fits the data is that cortical neurons receiving direct inputs from the primary sensory (lemniscal) pathway show the greatest decrement in synchrony following sensory deprivation, while neurons with diverse inputs from other areas of thalamus and cortex are relatively less affected in this dimension of cortical function.

  7. Motor cortex electric stimulation for the treatment of neuropathic pain

    Directory of Open Access Journals (Sweden)

    Walter J. Fagundes-Pereyra

    2010-12-01

    Full Text Available OBJECTIVE: Motor cortex stimulation (MCS is considered to be an effective treatment for chronic neuropathic pain. The aim of the present study was to assess the efficacy of MCS for treating neuropathic pain. METHOD: 27 patients with chronic neuropathic pain were operated. Electrodes were implanted with the use of an stereotactic frame. Electrophysiological evaluations (motor stimulation and somatosensory evoked potentials were performed, with guidance by means of three-dimensional reconstruction of magnetic resonance images of the brain. 10 patients (37% presented central neuropathic pain (post-stroke pain and 17 others (63% presented peripheral neuropathic pain (brachial plexus avulsion, phantom limb pain or trigeminal pain. RESULTS: In 15 patients (57.7% the pain relief was 50% or more; while in ten patients (38.5%, more than 60% of the original pain was relieved. No differences were found in relation to central and peripheral neuropathic pain (p=0.90, pain location (p=0.81, presence of motor deficit (p=0.28 and pain duration (p=0.72. No major complications were observed. CONCLUSION: MCS was efficient for treating patients presenting chronic central or peripheral neuropathic pain.

  8. Costs of control: decreased motor cortex engagement during a Go/NoGo task in Tourette's syndrome.

    Science.gov (United States)

    Thomalla, Götz; Jonas, Melanie; Bäumer, Tobias; Siebner, Hartwig R; Biermann-Ruben, Katja; Ganos, Christos; Orth, Michael; Hummel, Friedhelm C; Gerloff, Christian; Müller-Vahl, Kirsten; Schnitzler, Alfons; Münchau, Alexander

    2014-01-01

    Gilles de la Tourette syndrome is a neuropsychiatric disorder characterized by an impaired ability to inhibit unwanted behaviour. Although the presence of chronic motor and vocal tics defines Tourette's syndrome, other distinctive behavioural features like echo- and coprophenomena, and non-obscene socially inappropriate behaviour are also core features. We investigated neuronal activation during stimulus-driven execution and inhibition of prepared movements in Tourette's syndrome. To this end, we performed event-related functional magnetic resonance imaging and structural diffusion tensor imaging in 15 moderately affected uncomplicated patients with 'pure' Tourette's syndrome and 15 healthy control participants matched for age and gender. Subjects underwent functional magnetic resonance imaging during a Go/NoGo reaction time task. They had to withhold a prepared finger movement for a variable time until a stimulus instructed them to either execute (Go) or inhibit it (NoGo). Tics were monitored throughout the experiments, combining surface electromyogram, video recording, and clinical assessment in the scanner. Patients with Tourette's syndrome had longer reaction times than healthy controls in Go trials and made more errors in total. Their functional brain activation was decreased in left primary motor cortex and secondary motor areas during movement execution (Go trials) but not during response inhibition (NoGo trials) compared with healthy control subjects. Volume of interest analysis demonstrated less task-related activation in patients with Tourette's syndrome in primary and secondary motor cortex bilaterally, but not in the basal ganglia and cortical non-motor areas. They showed reduced co-activation between the left primary sensory-motor hand area and a network of contralateral sensory-motor areas and ipsilateral cerebellar regions. There were no between-group differences in structural connectivity of the left primary sensory-motor cortex as measured by

  9. Modeling the motor cortex: Optimality, recurrent neural networks, and spatial dynamics.

    Science.gov (United States)

    Tanaka, Hirokazu

    2016-03-01

    Specialization of motor function in the frontal lobe was first discovered in the seminal experiments by Fritsch and Hitzig and subsequently by Ferrier in the 19th century. It is, however, ironical that the functional and computational role of the motor cortex still remains unresolved. A computational understanding of the motor cortex equals to understanding what movement variables the motor neurons represent (movement representation problem) and how such movement variables are computed through the interaction with anatomically connected areas (neural computation problem). Electrophysiological experiments in the 20th century demonstrated that the neural activities in motor cortex correlated with a number of motor-related and cognitive variables, thereby igniting the controversy over movement representations in motor cortex. Despite substantial experimental efforts, the overwhelming complexity found in neural activities has impeded our understanding of how movements are represented in the motor cortex. Recent progresses in computational modeling have rekindled this controversy in the 21st century. Here, I review the recent developments in computational models of the motor cortex, with a focus on optimality models, recurrent neural network models and spatial dynamics models. Although individual models provide consistent pictures within their domains, our current understanding about functions of the motor cortex is still fragmented.

  10. Concurrent TMS to the primary motor cortex augments slow motor learning

    Science.gov (United States)

    Narayana, Shalini; Zhang, Wei; Rogers, William; Strickland, Casey; Franklin, Crystal; Lancaster, Jack L.; Fox, Peter T.

    2013-01-01

    Transcranial magnetic stimulation (TMS) has shown promise as a treatment tool, with one FDA approved use. While TMS alone is able to up- (or down-) regulate a targeted neural system, we argue that TMS applied as an adjuvant is more effective for repetitive physical, behavioral and cognitive therapies, that is, therapies which are designed to alter the network properties of neural systems through Hebbian learning. We tested this hypothesis in the context of a slow motor learning paradigm. Healthy right-handed individuals were assigned to receive 5 Hz TMS (TMS group) or sham TMS (sham group) to the right primary motor cortex (M1) as they performed daily motor practice of a digit sequence task with their non-dominant hand for 4 weeks. Resting cerebral blood flow (CBF) was measured by H215O PET at baseline and after 4 weeks of practice. Sequence performance was measured daily as the number of correct sequences performed, and modeled using a hyperbolic function. Sequence performance increased significantly at 4 weeks relative to baseline in both groups. The TMS group had a significant additional improvement in performance, specifically, in the rate of skill acquisition. In both groups, an improvement in sequence timing and transfer of skills to non-trained motor domains was also found. Compared to the sham group, the TMS group demonstrated increases in resting CBF specifically in regions known to mediate skill learning namely, the M1, cingulate cortex, putamen, hippocampus, and cerebellum. These results indicate that TMS applied concomitantly augments behavioral effects of motor practice, with corresponding neural plasticity in motor sequence learning network. These findings are the first demonstration of the behavioral and neural enhancing effects of TMS on slow motor practice and have direct application in neurorehabilitation where TMS could be applied in conjunction with physical therapy. PMID:23867557

  11. Concurrent TMS to the primary motor cortex augments slow motor learning.

    Science.gov (United States)

    Narayana, Shalini; Zhang, Wei; Rogers, William; Strickland, Casey; Franklin, Crystal; Lancaster, Jack L; Fox, Peter T

    2014-01-15

    Transcranial magnetic stimulation (TMS) has shown promise as a treatment tool, with one FDA approved use. While TMS alone is able to up- (or down-) regulate a targeted neural system, we argue that TMS applied as an adjuvant is more effective for repetitive physical, behavioral and cognitive therapies, that is, therapies which are designed to alter the network properties of neural systems through Hebbian learning. We tested this hypothesis in the context of a slow motor learning paradigm. Healthy right-handed individuals were assigned to receive 5 Hz TMS (TMS group) or sham TMS (sham group) to the right primary motor cortex (M1) as they performed daily motor practice of a digit sequence task with their non-dominant hand for 4 weeks. Resting cerebral blood flow (CBF) was measured by H2(15)O PET at baseline and after 4 weeks of practice. Sequence performance was measured daily as the number of correct sequences performed, and modeled using a hyperbolic function. Sequence performance increased significantly at 4 weeks relative to baseline in both groups. The TMS group had a significant additional improvement in performance, specifically, in the rate of skill acquisition. In both groups, an improvement in sequence timing and transfer of skills to non-trained motor domains was also found. Compared to the sham group, the TMS group demonstrated increases in resting CBF specifically in regions known to mediate skill learning namely, the M1, cingulate cortex, putamen, hippocampus, and cerebellum. These results indicate that TMS applied concomitantly augments behavioral effects of motor practice, with corresponding neural plasticity in motor sequence learning network. These findings are the first demonstration of the behavioral and neural enhancing effects of TMS on slow motor practice and have direct application in neurorehabilitation where TMS could be applied in conjunction with physical therapy.

  12. Improved methods for chronic light-based motor mapping in mice: automated movement tracking with accelerometers, and chronic EEG recording in a bilateral thin-skull preparation.

    Directory of Open Access Journals (Sweden)

    Gergely eSilasi

    2013-07-01

    Full Text Available Optogenetic stimulation of the mouse cortex can be used to generate motor maps that are similar to maps derived from electrode-based stimulation. Here we present a refined set of procedures for repeated light-based motor mapping in ChR2-expressing mice implanted with a bilateral thinned-skull chronic window and a chronically implanted EEG electrode. Light stimulation is delivered sequentially to over 400 points across the cortex, and evoked movements are quantified on-line with a 3-axis accelerometer attached to each forelimb. Bilateral maps of forelimb movement amplitude and movement direction were generated at weekly intervals after recovery from cranial window implantation. We found that light pulses of ~2 mW produced well-defined maps that were centered approximately 0.7 mm anterior and 1.6 mm lateral from bregma. Map borders were defined by sites where light stimulation evoked EEG deflections, but not movements. Motor maps were similar in size and location between mice, and maps were stable over weeks in terms of the number of responsive sites, and the direction of evoked movements. We suggest that our method may be used to chronically assess evoked motor output in mice, and may be combined with other imaging tools to assess cortical reorganization or sensory-motor integration.

  13. Functional connectivity of human premotor and motor cortex explored with repetitive transcranial magnetic stimulation.

    NARCIS (Netherlands)

    Munchau, A.; Bloem, B.R.; Irlbacher, K.; Trimble, M.R.; Rothwell, J.C.

    2002-01-01

    Connections between the premotor cortex and the primary motor cortex are dense and are important in the visual guidance of arm movements. We have shown previously that it is possible to engage these connections in humans and to measure the net amount of inhibition/facilitation from premotor to motor

  14. Continuous theta-burst stimulation of the primary motor cortex in essential tremor

    DEFF Research Database (Denmark)

    Hellriegel, Helge; Schulz, Eva M; Siebner, Hartwig R

    2012-01-01

    We investigated whether essential tremor (ET) can be altered by suppressing the corticospinal excitability in the primary motor cortex (M1) with transcranial magnetic stimulation.......We investigated whether essential tremor (ET) can be altered by suppressing the corticospinal excitability in the primary motor cortex (M1) with transcranial magnetic stimulation....

  15. Disrupting the ipsilateral motor cortex interferes with training of a complex motor task in older adults.

    Science.gov (United States)

    Zimerman, Máximo; Heise, Kirstin-F; Gerloff, Christian; Cohen, Leonardo G; Hummel, Friedhelm C

    2014-04-01

    Performance of unimanual movements is associated with bihemispheric activity in the motor cortex in old adults. However, the causal functional role of the ipsilateral MC (iMC) for motor control is still not completely known. Here, the behavioral consequences of interference of the iMC during training of a complex motor skill were tested. Healthy old (58-85 years) and young volunteers (22-35 years) were tested in a double-blind, cross-over, sham-controlled design. Participants attended 2 different study arms with either cathodal transcranial direct current stimulation (ctDCS) or sham concurrent with training. Motor performance was evaluated before, during, 90 min, and 24 h after training. During training, a reduced slope of performance with ctDCS relative to sham was observed in old compared with young (F = 5.8, P = 0.02), with a decrease of correctly rehearsed sequences, an effect that was evident even after 2 consecutive retraining periods without intervention. Furthermore, the older the subject, the more prominent was the disruptive effect of ctDCS (R(2) = 0.50, P = 0.01). These data provide direct evidence for a causal functional link between the iMC and motor skill acquisition in old subjects pointing toward the concept that the recruitment of iMC in old is an adaptive process in response to age-related declines in motor functions.

  16. Negative blood oxygenation level dependent homunculus and somatotopic information in primary motor cortex and supplementary motor area.

    Science.gov (United States)

    Zeharia, Noa; Hertz, Uri; Flash, Tamar; Amedi, Amir

    2012-11-06

    A crucial attribute in movement encoding is an adequate balance between suppression of unwanted muscles and activation of required ones. We studied movement encoding across the primary motor cortex (M1) and supplementary motor area (SMA) by inspecting the positive and negative blood oxygenation level-dependent (BOLD) signals in these regions. Using periodic and event-related experiments incorporating the bilateral/axial movements of 20 body parts, we report detailed mototopic imaging maps in M1 and SMA. These maps were obtained using phase-locked analysis. In addition to the positive BOLD, significant negative BOLD was detected in M1 but not in the SMA. The negative BOLD spatial pattern was neither located at the ipsilateral somatotopic location nor randomly distributed. Rather, it was organized somatotopically across the entire homunculus and inversely to the positive BOLD, creating a negative BOLD homunculus. The neuronal source of negative BOLD is unclear. M1 provides a unique system to test whether the origin of negative BOLD is neuronal, because different arteries supply blood to different regions in the homunculus, ruling out blood-stealing explanations. Finally, multivoxel pattern analysis showed that positive BOLD in M1 and SMA and negative BOLD in M1 contain somatotopic information, enabling prediction of the moving body part from inside and outside its somatotopic location. We suggest that the neuronal processes underlying negative BOLD participate in somatotopic encoding in M1 but not in the SMA. This dissociation may emerge because of differences in the activity of these motor areas associated with movement suppression.

  17. Optimization of mirror therapy to excite ipsilateral primary motor cortex.

    Science.gov (United States)

    Hadoush, Hikmat; Mano, Hirofumi; Sunagawa, Toru; Nakanishi, Kazuyoshi; Ochi, Mitsu

    2013-01-01

    Mirror illusion therapy (mirror therapy) is based on the experimental substrate of a visual illusion of active hand movement to excite ipsilateral primary motor cortex (iM1). We tested whether iM1 excitability could be modulated by enabling or disabling vision of the active hand during mirror therapy. Motor cortical activations of healthy right-handed participants were identified by magnetoencephalography. Participants performed voluntary index finger extension of their dominant and non-dominant hands, separately, while viewing mirror reflection images of their active hand superimposed upon their hidden inactive hand. This was performed either with vision of the active hand (uncovered viewing condition) or without vision of the active hand (covered viewing condition). In the covered viewing condition, the iM1could be excited in all participants (n = 10) and this excitation did not differ whether the active hand was the dominant or non-dominant hand. However, in the uncovered viewing condition, dominant and non-dominant hands were able to excite iM1 only in some participants (n = 4 and n = 7, respectively). Moreover, the participants' responses to the illusion validation questionnaire revealed that the covered viewing condition could cause clearer visual illusion for the active hand than the uncovered viewing condition. Disabling vision of the active hand during mirror therapy was more effective to excite iM1 responses by creating more immersive visual illusion of the active hand.

  18. Neurofilament heavy chain expression and neuroplasticity in rat auditory cortex after unilateral and bilateral deafness.

    Science.gov (United States)

    Park, Min-Hyun; Jang, Jeong Hun; Song, Jae-Jin; Lee, Ho Sun; Oh, Seung Ha

    2016-09-01

    Deafness induces many plastic changes in the auditory neural system. For instance, dendritic changes cause synaptic changes in neural cells. SMI-32, a monoclonal antibody reveals auditory areas and recognizes non-phosphorylated epitopes on medium- and high-molecular-weight subunits of neurofilament proteins in cortical pyramidal neuron dendrites. We investigated SMI-32-immunoreactive (-ir) protein levels in the auditory cortices of rats with induced unilateral and bilateral deafness. Adult male Sprague-Dawley rats were divided into unilateral deafness (UD), bilateral deafness (BD), and control groups. Deafness was induced by cochlear ablation. All rats were sacrificed, and the auditory cortices were harvested for real-time quantitative polymerase chain reaction (RT-qPCR) and western blot analyses at 2, 4, 6, and 12 weeks after deafness was induced. Immunohistochemical staining was performed to evaluate the location of SMI-32-ir neurons. Neurofilament heavy chain (NEFH) mRNA expression and SMI-32-ir protein levels were increased in the BD group. In particular, SMI-32-ir protein levels increased significantly 6 and 12 weeks after deafness was induced. In contrast, no significant changes in protein level were detected in the right or left auditory cortices at any time point in the UD group. NEFH mRNA level decreased at 4 weeks after deafness was induced in the UD group, but recovered thereafter. Taken together, BD induced plastic changes in the auditory cortex, whereas UD did not affect the auditory neural system sufficiently to show plastic changes, as measured by neurofilament protein level.

  19. Interactions between Pain and the Motor Cortex: Insights from Research on Phantom Limb Pain and Complex Regional Pain Syndrome

    OpenAIRE

    Mercier, Catherine; Léonard, Guillaume

    2011-01-01

    Purpose: Pain is a significantly disabling problem that often interacts with other deficits during the rehabilitation process. The aim of this paper is to review evidence of interactions between pain and the motor cortex in order to attempt to answer the following questions: (1) Does acute pain interfere with motor-cortex activity? (2) Does chronic pain interfere with motor-cortex activity, and, conversely, does motor-cortex plasticity contribute to chronic pain? (3) Can the induction of moto...

  20. Interictal inhibitory mechanisms in patients with cryptogenic motor cortex epilepsy: a study of the silent period following transcranial magnetic stimulation.

    Science.gov (United States)

    Cincotta, M; Borgheresi, A; Lori, S; Fabbri, M; Zaccara, G

    1998-07-01

    The silent period (SP) following transcranial magnetic stimulation (TMS) of the motor cortex is mainly due to cortical inhibitory mechanisms. The aim of the present study was to investigate these inhibitory phenomena in primary motor cortex epilepsy. We studied the TMS-induced SP in both the first dorsal interosseous (FDI) muscles in 8 patients who suffered from cryptogenic partial epilepsy with seizures starting with clonic movements of the right upper limb. All patients were on chronic medication with antiepileptic drugs. Therefore, besides contrasting the results with 16 age-matched normal controls, we also studied 10 patients receiving similar antiepileptic treatments who suffered from cryptogenic partial epilepsy with seizures characterised by the absence of clonic manifestations. The duration of the SP was bilaterally increased in the patients with clonic seizures when compared with the two other groups of subjects. The SP was longer in the left FDI muscle (contralateral to the side of the clonic manifestation in all the patients). Our findings likely indicate enhanced interictal inhibitory mechanisms in patients with partial epilepsy involving the primary motor cortex. The resulting inhibitory effect could be greater in the intact hemisphere rather than in the affected one, in which the hyperexcitability of the epileptic focus had to be counterbalanced.

  1. Primary motor cortex contributes to the implementation of implicit value-based rules during motor decisions.

    Science.gov (United States)

    Derosiere, Gerard; Zénon, Alexandre; Alamia, Andrea; Duque, Julie

    2017-02-01

    In the present study, we investigated the functional contribution of the human primary motor cortex (M1) to motor decisions. Continuous theta burst stimulation (cTBS) was used to alter M1 activity while participants performed a decision-making task in which the reward associated with the subjects' responses (right hand finger movements) depended on explicit and implicit value-based rules. Subjects performed the task over two consecutive days and cTBS occurred in the middle of Day 2, once the subjects were just about to implement implicit rules, in addition to the explicit instructions, to choose their responses, as evident in the control group (cTBS over the right somatosensory cortex). Interestingly, cTBS over the left M1 prevented subjects from implementing the implicit value-based rule while its implementation was enhanced in the group receiving cTBS over the right M1. Hence, cTBS had opposite effects depending on whether it was applied on the contralateral or ipsilateral M1. The use of the explicit value-based rule was unaffected by cTBS in the three groups of subject. Overall, the present study provides evidence for a functional contribution of M1 to the implementation of freshly acquired implicit rules, possibly through its involvement in a cortico-subcortical network controlling value-based motor decisions.

  2. A Neurobehavioral Investigation into Judgmental Processes: Effect of Bilateral Motor Behaviors

    Science.gov (United States)

    Cretenet, Joel; Dru, Vincent

    2008-01-01

    Two experiments were conducted in order to examine how different bilateral motor activations of the approach and avoidance motivational systems influenced participants' evaluations of valenced stimuli (figurative expressions and pictures of everyday situations). The first Study (Study 1) showed that participants judged valenced expressions…

  3. Rat whisker motor cortex is subdivided into sensory-input and motor-output areas.

    Science.gov (United States)

    Smith, Jared B; Alloway, Kevin D

    2013-01-01

    Rodent whisking is an exploratory behavior that can be modified by sensory feedback. Consistent with this, many whisker-sensitive cortical regions project to agranular motor [motor cortex (MI)] cortex, but the relative topography of these afferent projections has not been established. Intracortical microstimulation (ICMS) evokes whisker movements that are used to map the functional organization of MI, but no study has compared the whisker-related inputs to MI with the ICMS sites that evoke whisker movements. To elucidate this relationship, anterograde tracers were placed in posterior parietal cortex (PPC) and in the primary somatosensory (SI) and secondary somatosensory (SII) cortical areas so that their labeled projections to MI could be analyzed with respect to ICMS sites that evoke whisker movements. Projections from SI and SII terminate in a narrow zone that marks the transition between the medial agranular (AGm) and lateral agranular (AGl) cortical areas, but PPC projects more medially and terminates in AGm proper. Paired recordings of MI neurons indicate that the region between AGm and AGl is highly responsive to whisker deflections, but neurons in AGm display negligible responses to whisker stimulation. By contrast, AGm microstimulation is more effective in evoking whisker movements than microstimulation of the transitional region between AGm and AGl. The AGm region was also found to contain a larger concentration of corticotectal neurons, which could convey whisker-related information to the facial nucleus. These results indicate that rat whisker MI is comprised of at least two functionally distinct subregions: a sensory processing zone in the transitional region between AGm and AGl, and a motor-output region located more medially in AGm proper.

  4. Rat whisker motor cortex is subdivided into sensory-input and motor-output areas

    Directory of Open Access Journals (Sweden)

    Jared B Smith

    2013-01-01

    Full Text Available Rodent whisking is an exploratory behavior that can be modified by sensory feedback. Consistent with this, many whisker-sensitive cortical regions project to agranular motor (MI cortex, but the relative topography of these afferent projections has not been established. Intracranial microstimulation (ICMS evokes whisker movements that are used to map the functional organization of MI, but no study has compared the whisker-related inputs to MI with the ICMS sites that evoke whisker movements. To elucidate this relationship, anterograde tracers were placed in posterior parietal cortex (PPC and in the primary (SI and secondary (SII somatosensory cortical areas so that their labeled projections to MI could be analyzed with respect to ICMS sites that evoke whisker movements. Projections from SI and SII terminate in a narrow zone that marks the transition between the medial (AGm and lateral agranular (AGl cortical areas, but PPC projects more medially and terminates in AGm proper. Paired recordings of MI neurons indicate that the region between AGm and AGl is highly responsive to whisker deflections, but neurons in AGm display negligible responses to whisker stimulation. By contrast, AGm microstimulation is more effective in evoking whisker movements than microstimulation of the transitional region between AGm and AGl. The AGm region was also found to contain a larger concentration of corticotectal neurons, which could convey whisker-related information to the facial nucleus. These results indicate that rat whisker motor cortex is comprised of at least two functionally distinct subregions: a sensory processing zone in the transitional region between AGm and AGl, and a motor output region located more medially in AGm proper.

  5. Motor cortex changes after amputation are modulated by phantom limb motor control rather than pain

    DEFF Research Database (Denmark)

    Raffin, Estelle E.; Pascal, Giraux,; Karen, Reilly,

    retains a residual M1-c activity when amputees perform phantom limb movements (4-5). Except a correlation between phantom limb pain and M1-c expansion of the face (2-3), the relationship between the ability to voluntary move the phantom hand, the level of phantom limb pain, the degree of M1-c......Amputation of a limb induces reorganization within the contralateral primary motor cortex (M1-c) (1-3). In the case of hand amputation, M1-c areas evoking movements in the face and the remaining part of the upper-limb expand toward the hand area. Despite this expansion, the amputated hand still...

  6. Induction of plasticity in the human motor cortex by pairing an auditory stimulus with TMS.

    Science.gov (United States)

    Sowman, Paul F; Dueholm, Søren S; Rasmussen, Jesper H; Mrachacz-Kersting, Natalie

    2014-01-01

    Acoustic stimuli can cause a transient increase in the excitability of the motor cortex. The current study leverages this phenomenon to develop a method for testing the integrity of auditorimotor integration and the capacity for auditorimotor plasticity. We demonstrate that appropriately timed transcranial magnetic stimulation (TMS) of the hand area, paired with auditorily mediated excitation of the motor cortex, induces an enhancement of motor cortex excitability that lasts beyond the time of stimulation. This result demonstrates for the first time that paired associative stimulation (PAS)-induced plasticity within the motor cortex is applicable with auditory stimuli. We propose that the method developed here might provide a useful tool for future studies that measure auditory-motor connectivity in communication disorders.

  7. Functional Magnetic Resonance Imaging of Motor Cortex: Hemispheric Asymmetry and Handedness

    Science.gov (United States)

    Kim, Seong-Gi; Ashe, James; Hendrich, Kristy; Ellermann, Jutta M.; Merkle, Hellmut; Ugurbil, Kamil; Georgopoulos, Apostolos P.

    1993-07-01

    A hemispheric asymmetry in the functional activation of the human motor cortex during contralateral (C) and ipsilateral (I) finger movements, especially in right-handed subjects, was documented with nuclear magnetic resonance imaging at high field strength (4 tesla). Whereas the right motor cortex was activated mostly during contralateral finger movements in both right-handed (C/I mean area of activation = 36.8) and left-handed (C/I = 29.9) subjects, the left motor cortex was activated substantially during ipsilateral movements in left-handed subjects (C/I = 5.4) and even more so in right-handed subjects (C/I = 1.3).

  8. Acute aerobic exercise modulates primary motor cortex inhibition.

    Science.gov (United States)

    Mooney, Ronan A; Coxon, James P; Cirillo, John; Glenny, Helen; Gant, Nicholas; Byblow, Winston D

    2016-12-01

    Aerobic exercise can enhance neuroplasticity although presently the neural mechanisms underpinning these benefits remain unclear. One possible mechanism is through effects on primary motor cortex (M1) function via down-regulation of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA). The aim of the present study was to examine how corticomotor excitability (CME) and M1 intracortical inhibition are modulated in response to a single bout of moderate intensity aerobic exercise. Ten healthy right-handed adults were participants. Single- and paired-pulse transcranial magnetic stimulation was applied over left M1 to obtain motor-evoked potentials in the right flexor pollicis brevis. We examined CME, cortical silent period (SP) duration, short- and long-interval intracortical inhibition (SICI, LICI), and late cortical disinhibition (LCD), before and after acute aerobic exercise (exercise session) or an equivalent duration without exercise (control session). Aerobic exercise was performed on a cycle ergometer for 30 min at a workload equivalent to 60 % of maximal cardiorespiratory fitness (VO2 peak; heart rate reserve = 75 ± 3 %, perceived exertion = 13.5 ± 0.7). LICI was reduced at 10 (52 ± 17 %, P = 0.03) and 20 min (27 ± 8 %, P = 0.03) post-exercise compared to baseline (13 ± 4 %). No significant changes in CME, SP duration, SICI or LCD were observed. The present study shows that GABAB-mediated intracortical inhibition may be down-regulated after acute aerobic exercise. The potential effects this may have on M1 plasticity remain to be determined.

  9. Neurons in Primary Motor Cortex Engaged During Action Observation

    Science.gov (United States)

    Dushanova, Juliana; Donoghue, John

    2010-01-01

    Neurons in higher cortical areas appear to become active during action observation, either by mirroring observed actions (termed mirror neurons) or by eliciting mental rehearsal of observed motor acts. We report the existence of neurons in primary motor cortex (MI) responding to viewed actions, an area generally considered to initiate and guide movement performance. Multielectrode recordings in monkeys performing or observing a well-learned step tracking task showed that approximately half of MI neurons, active when monkeys performed the task, were also active when they observed the action being performed by a human. These ‘view’ neurons were spatially intermingled with ‘do’ neurons, active only during movement performance. Simultaneously recorded, ‘view’ neurons comprised two groups: ∼38% retained the same preferred direction (PD) and timing during performance and viewing, while the remainder (62%) changed their PDs and time lag during viewing compared with performance. Nevertheless, population activity during viewing was sufficient to predict the direction and trajectory of viewed movements as action unfolded, although less accurately than during performance. ‘View’ neurons became less active and contained poorer representations of action when viewing only sub-components of the task. MI ‘view’ neurons thus appear to reflect the aspects of a learned movement when observed in others and form part of a broadly engaged set of cortical areas routinely responding to learned behaviors. These findings suggest that viewing a learned action elicits replay of aspects of MI activity needed to perform the observed action and could additionally reflect processing related to understanding, learning or mentally rehearsing action. PMID:20074212

  10. Increased resting state connectivity between ipsilesional motor cortex and contralesional premotor cortex after transcranial direct current stimulation with physical therapy.

    Science.gov (United States)

    Chen, Joyce L; Schlaug, Gottfried

    2016-03-16

    Non-invasive stimulation of the brain using transcranial direct current stimulation (tDCS) during motor rehabilitation can improve the recovery of movements in individuals with stroke. However, the neural substrates that underlie the clinical improvements are not well understood. In this proof-of-principle open-label pilot study, five individuals with stroke received 10 sessions of tDCS while undergoing usual care physical/occupational therapy for the arm and hand. Motor impairment as indexed by the Upper Extremity Fugl Meyer assessment was significantly reduced after the intervention. Resting state fMRI connectivity increased between ipsilesional motor cortex and contralesional premotor cortex after the intervention. These findings provide preliminary evidence that the neural underpinnings of tDCS coupled with rehabilitation exercises, may be mediated by interactions between motor and premotor cortex. The latter, of which has been shown to play an important role in the recovery of movements post-stroke. Our data suggest premotor cortex could be tested as a target region for non-invasive brain-stimulation to enhance connectivity between regions that might be beneficial for stroke motor recovery.

  11. Increased resting state connectivity between ipsilesional motor cortex and contralesional premotor cortex after transcranial direct current stimulation with physical therapy

    Science.gov (United States)

    Chen, Joyce L; Schlaug, Gottfried

    2016-01-01

    Non-invasive stimulation of the brain using transcranial direct current stimulation (tDCS) during motor rehabilitation can improve the recovery of movements in individuals with stroke. However, the neural substrates that underlie the clinical improvements are not well understood. In this proof-of-principle open-label pilot study, five individuals with stroke received 10 sessions of tDCS while undergoing usual care physical/occupational therapy for the arm and hand. Motor impairment as indexed by the Upper Extremity Fugl Meyer assessment was significantly reduced after the intervention. Resting state fMRI connectivity increased between ipsilesional motor cortex and contralesional premotor cortex after the intervention. These findings provide preliminary evidence that the neural underpinnings of tDCS coupled with rehabilitation exercises, may be mediated by interactions between motor and premotor cortex. The latter, of which has been shown to play an important role in the recovery of movements post-stroke. Our data suggest premotor cortex could be tested as a target region for non-invasive brain-stimulation to enhance connectivity between regions that might be beneficial for stroke motor recovery. PMID:26980052

  12. A threat to a virtual hand elicits motor cortex activation.

    Science.gov (United States)

    González-Franco, Mar; Peck, Tabitha C; Rodríguez-Fornells, Antoni; Slater, Mel

    2014-03-01

    We report an experiment where participants observed an attack on their virtual body as experienced in an immersive virtual reality (IVR) system. Participants sat by a table with their right hand resting upon it. In IVR, they saw a virtual table that was registered with the real one, and they had a virtual body that substituted their real body seen from a first person perspective. The virtual right hand was collocated with their real right hand. Event-related brain potentials were recorded in two conditions, one where the participant's virtual hand was attacked with a knife and a control condition where the knife only struck the virtual table. Significantly greater P450 potentials were obtained in the attack condition confirming our expectations that participants had a strong illusion of the virtual hand being their own, which was also strongly supported by questionnaire responses. Higher levels of subjective virtual hand ownership correlated with larger P450 amplitudes. Mu-rhythm event-related desynchronization in the motor cortex and readiness potential (C3-C4) negativity were clearly observed when the virtual hand was threatened-as would be expected, if the real hand was threatened and the participant tried to avoid harm. Our results support the idea that event-related potentials may provide a promising non-subjective measure of virtual embodiment. They also support previous experiments on pain observation and are placed into context of similar experiments and studies of body perception and body ownership within cognitive neuroscience.

  13. Resting‐state connectivity of pre‐motor cortex reflects disability in multiple sclerosis

    DEFF Research Database (Denmark)

    Dogonowski, Anne-Marie; Siebner, Hartwig Roman; Soelberg Sørensen, P.

    2013-01-01

    Objective To characterize the relationship between motor resting-state connectivity of the dorsal pre-motor cortex (PMd) and clinical disability in patients with multiple sclerosis (MS). Materials and methods A total of 27 patients with relapsing–remitting MS (RR-MS) and 15 patients with secondary...... be interpreted as adaptive reorganization of the motor system to maintain motor function, which appears to be limited to the relapsing–remitting stage of the disease....

  14. Inter-individual variability in optimal current direction for transcranial magnetic stimulation of the motor cortex

    DEFF Research Database (Denmark)

    Balslev, Daniela; Braet, Wouter; McAllister, Craig

    2007-01-01

    We evaluated inter-individual variability in optimal current direction for biphasic transcranial magnetic stimulation (TMS) of the motor cortex. Motor threshold for first dorsal interosseus was detected visually at eight coil orientations in 45 degrees increments. Each participant (n=13) completed...... two experimental sessions. One participant with low test-retest correlation (Pearson's rvisual detection of motor threshold was compared to EMG detection; motor thresholds were very similar and highly correlated (0.94-0.99). Similar with previous studies...

  15. Rapid Modulation of Distributed Brain Activity by Transcranial Magnetic Stimulation of Human Motor Cortex

    OpenAIRE

    Lucy Lee; Hartwig Siebner; Sven Bestmann

    2006-01-01

    This paper reviews the effects of single and repetitive transcranial magnetic stimuli (rTMS) delivered to one cortical area and measured across distributed brain regions using electrophysiological measures (e.g. motor thresholds, motor evoked potentials, paired-pulse stimulation), functional neuroimaging (including EEG, PET and fMRI) and behavioural measures. Discussion is restricted to changes in excitability in the primary motor cortex and behaviour during motor tasks following transcranial...

  16. Interhemispheric interaction between human dorsal premotor and contralateral primary motor cortex.

    Science.gov (United States)

    Mochizuki, Hitoshi; Huang, Ying-Zu; Rothwell, John C

    2004-11-15

    We used transcranial magnetic stimulation (TMS) in a paired pulse protocol to investigate interhemispheric interactions between the right dorsal premotor (dPM) and left primary motor cortex (M1) using interstimulus intervals of 4, 6, 8, 10, 12, 16 and 20 ms in ten healthy subjects. A conditioning stimulus over right dPM at an intensity of either 90 or 110% resting motor threshold (RMT) suppressed motor-evoked potentials (MEPs) evoked in the first dorsal interosseous (FDI) muscle by stimulation of left M1. Maximum effects occurred for interstimulus intervals (ISIs) of 8-10 ms. There was no effect if the conditioning stimulus was applied 2.5 cm lateral, anterior or medial to dPM. The effect differed from previously described M1 interhemispheric inhibition in that the threshold for the latter was greater than 90% RMT, whereas stimulation of the dPM at the same intensity led to significant inhibition. In addition, voluntary contraction of the left FDI (i.e. contralateral to the conditioning TMS) enhanced interhemispheric inhibition from right M1 but had no effect on the inhibition from right dPM. Finally, conditioning to right dPM at 90% RMT reduced short-interval intracortical inhibition (SICI; at ISI = 2 ms) in left M1 whilst there was no effect if the conditioning stimulus was applied to right M1. We conclude that conditioning TMS over dPM has effects that differ from the previous pattern of interhemispheric inhibition described between bilateral M1s. This may reflect the existence of commissural fibres between dPM and contralateral M1 that may play a role in bimanual coordination.

  17. The prefrontal cortex shows context-specific changes in effective connectivity to motor or visual cortex during the selection of action or colour

    DEFF Research Database (Denmark)

    Rowe, James B.; Stephan, Klaas E.; Friston, Karl

    2005-01-01

    The role of the prefrontal cortex remains controversial. Neuroimaging studies support modality-specific and process-specific functions related to working memory and attention. Its role may also be defined by changes in its influence over other brain regions including sensory and motor cortex. We...... included high-order interactions between modality, selection and regional activity. There was greater coupling between prefrontal cortex and motor cortex during free selection and action tasks, and between prefrontal cortex and visual cortex during free selection of colours. The results suggest...

  18. Influences of dopaminergic treatment on motor cortex in Parkinson disease: a MRI/MRS study.

    Science.gov (United States)

    Lucetti, Claudio; Del Dotto, Paulo; Gambaccini, Gianna; Ceravolo, Roberto; Logi, Chiara; Berti, Caterina; Rossi, Giuseppe; Bianchi, Maria Cristina; Tosetti, Michela; Murri, Luigi; Bonuccelli, Ubaldo

    2007-11-15

    The objective of this study was to investigate neurochemical and metabolic changes in the motor cortex in a group of de novo Parkinson's disease (PD) patients before and after 6 mo treatment with the dopamine agonist pergolide. Proton magnetic resonance spectroscopy (1H-MRS) has been used to study striatal and cortical metabolism in PD and other parkinsonisms. So far, no studies evaluating possible brain metabolic changes in PD patients before and after dopaminergic therapy have been reported. De novo PD patients (11) and controls (11) underwent clinical evaluation (UPDRS-III motor evaluation) and a first single-voxel 1H-MRS of the motor cortex. 1H-MRS studies were performed using the PROBE-SV System implemented on a 1.5 Tesla Scanner (GE Medical System, Milwaukee, WI). Pergolide was administered up to a dose of 1 mg t.i.d. After 6 mo follow-up, all patients were clinically evaluated and a second single-voxel 1H-MRS was performed. Lower values of Cho/Cr and NAA/Cr ratios were observed in the motor cortex of PD patients compared with controls (P motor performances (P motor cortex at the second 1H-MRS evaluation (P motor function may restore the Cho/Cr ratio in the motor cortex. (c) 2007 Movement Disorder Society.

  19. 3D visualization of movements can amplify motor cortex activation during subsequent motor imagery.

    Science.gov (United States)

    Sollfrank, Teresa; Hart, Daniel; Goodsell, Rachel; Foster, Jonathan; Tan, Tele

    2015-01-01

    A repetitive movement practice by motor imagery (MI) can influence motor cortical excitability in the electroencephalogram (EEG). This study investigated if a realistic visualization in 3D of upper and lower limb movements can amplify motor related potentials during subsequent MI. We hypothesized that a richer sensory visualization might be more effective during instrumental conditioning, resulting in a more pronounced event related desynchronization (ERD) of the upper alpha band (10-12 Hz) over the sensorimotor cortices thereby potentially improving MI based brain-computer interface (BCI) protocols for motor rehabilitation. The results show a strong increase of the characteristic patterns of ERD of the upper alpha band components for left and right limb MI present over the sensorimotor areas in both visualization conditions. Overall, significant differences were observed as a function of visualization modality (VM; 2D vs. 3D). The largest upper alpha band power decrease was obtained during MI after a 3-dimensional visualization. In total in 12 out of 20 tasks the end-user of the 3D visualization group showed an enhanced upper alpha ERD relative to 2D VM group, with statistical significance in nine tasks.With a realistic visualization of the limb movements, we tried to increase motor cortex activation during subsequent MI. The feedback and the feedback environment should be inherently motivating and relevant for the learner and should have an appeal of novelty, real-world relevance or aesthetic value (Ryan and Deci, 2000; Merrill, 2007). Realistic visual feedback, consistent with the participant's MI, might be helpful for accomplishing successful MI and the use of such feedback may assist in making BCI a more natural interface for MI based BCI rehabilitation.

  20. Developmental changes in motor cortex activity as infants develop functional motor skills.

    Science.gov (United States)

    Nishiyori, Ryota; Bisconti, Silvia; Meehan, Sean K; Ulrich, Beverly D

    2016-09-01

    Despite extensive research examining overt behavioral changes of motor skills in infants, the neural basis underlying the emergence of functional motor control has yet to be determined. We used functional near-infrared spectroscopy (fNIRS) to record hemodynamic activity of the primary motor cortex (M1) from 22 infants (11 six month-olds, 11 twelve month-olds) as they reached for an object, and stepped while supported over a treadmill. Based on the developmental systems framework, we hypothesized that as infants increased goal-directed experience, neural activity shifts from a diffused to focal pattern. Results showed that for reaching, younger infants showed diffuse areas of M1 activity that became focused by 12 months. For elicited stepping, younger infants produced much less M1 activity which shifted to diffuse activity by 12 months. Thus, the data suggest that as infants gain goal-directed experience, M1 activity emerges, initially showing a diffuse area of activity, becoming refined as the behavior stabilizes. Our data begin to document the cortical activity underlying early functional skill acquisition.

  1. Changes of Brain Connectivity in the Primary Motor Cortex After Subcortical Stroke: A Multimodal Magnetic Resonance Imaging Study.

    Science.gov (United States)

    Li, Yongxin; Wang, Defeng; Zhang, Heye; Wang, Ya; Wu, Ping; Zhang, Hongwu; Yang, Yang; Huang, Wenhua

    2016-02-01

    The authors investigated the changes in connectivity networks of the bilateral primary motor cortex (M1) of subcortical stroke patients using a multimodal neuroimaging approach with antiplatelet therapy. Nineteen patients were scanned at 2 time points: before and 1 month after the treatment. The authors assessed the resting-state functional connectivity (FC) and probabilistic fiber tracking of left and right M1 of every patient, and then compared these results to the 15 healthy controls. The authors also evaluated the correlations between the neuroimaging results and clinical scores.Compared with the controls, the patients showed a significant decrease of FC in the contralateral motor cortex before treatment, and the disrupted FC was restored after treatment. The fiber tracking results in the controls indicated that the body of the corpus callosum should be the main pathway connecting the M1 and contralateral hemispheres. All patients exhibited reduced probability of structural connectivity within this pathway before treatment and which was restored after treatment. Significant correlations were also found in these patients between the connectivity results and clinical scores, which might imply that the connectivity of M1 can be used to evaluate the motor skills in stroke patients.These findings can help elucidate the neural mechanisms responsible for the brain connectivity recovery after stroke.

  2. DETECTING BILATERAL FUNCTIONAL CONNECTIVITY IN THE PREFRONTAL CORTEX DURING A STROOP TASK BY NEAR-INFRARED SPECTROSCOPY

    Directory of Open Access Journals (Sweden)

    LEI ZHANG

    2013-10-01

    Full Text Available Near-infrared spectroscopy (NIRS is generally accepted as a functional brain imaging technology for brain activation study. With multichannel highly sensitive NIRS instruments, it has become possible to assess functional connectivity of different brain regions by NIRS. However, the feasibility needs to be validated in complex cognitive activities. In this study, we recorded the hemodynamic activity of the bilateral prefrontal cortex (PFC during a color-word matching Stroop task. Wavelet transform coherence (WTC analysis was applied to assess the functional connectivity of all homologous channel pairs within the left/right PFC. Both the behavioral and brain activation results showed significant Stroop effects. The results of WTC analysis revealed that, bilateral functional connectivity was significantly stronger during both the incongruent stimuli and neutral stimuli compared to that of the rest period. It also showed significant Stroop effect. Our findings demonstrate that, NIRS becomes a valuable tool to elucidate the functional connectivity of brain cortex in complex cognitive activities.

  3. Bilateral deficits in fine motor control ability and manual dexterity in women with fibromyalgia syndrome.

    Science.gov (United States)

    Pérez-de-Heredia-Torres, Marta; Martínez-Piédrola, Rosa M; Cigarán-Méndez, Margarita; Ortega-Santiago, Ricardo; Fernández-de-Las-Peñas, César

    2013-04-01

    The aim of the current study was to investigate fine motor control ability and manual dexterity women with fibromyalgia syndrome (FMS) without symptoms in the upper extremity compared to healthy women. Subtests of the Purdue Pegboard Test (one-hand, bilateral and assembly) and of the Jebsen-Taylor hand-function test (writing, turning cards, picking up small, light and large heavy objects, simulated feeding and stacking checkers) were evaluated bilaterally in 20 women with FMS (aged 35-55 years) without symptoms in the upper limb and 20 age- and hand dominance-matched healthy women. Differences between sides and groups were analysed with several analysis of variance (ANOVA). The ANOVA revealed significant differences between groups (P controls. Patients also exhibited significantly lower scores in bilateral pin placement and assembly subtests when compared to healthy controls (P motor control ability and manual dexterity in patients with FMS without symptoms in the upper extremity. These deficits are not related to the clinical features of the symptoms supporting an underlying central mechanism of altered motor control.

  4. Laterality of movement-related activity reflects transformation of coordinates in ventral premotor cortex and primary motor cortex of monkeys.

    Science.gov (United States)

    Kurata, Kiyoshi

    2007-10-01

    The ventral premotor cortex (PMv) and the primary motor cortex (MI) of monkeys participate in various sensorimotor integrations, such as the transformation of coordinates from visual to motor space, because the areas contain movement-related neuronal activity reflecting either visual or motor space. In addition to relationship to visual and motor space, laterality of the activity could indicate stages in the visuomotor transformation. Thus we examined laterality and relationship to visual and motor space of movement-related neuronal activity in the PMv and MI of monkeys performing a fast-reaching task with the left or right arm, toward targets with visual and motor coordinates that had been dissociated by shift prisms. We determined laterality of each activity quantitatively and classified it into four types: activity that consistently depended on target locations in either head-centered visual coordinates (V-type) or motor coordinates (M-type) and those that had either differential or nondifferential activity for both coordinates (B- and N-types). A majority of M-type neurons in the areas had preferences for reaching movements with the arm contralateral to the hemisphere where neuronal activity was recorded. In contrast, most of the V-type neurons were recorded in the PMv and exhibited less laterality than the M-type. The B- and N-types were recorded in the PMv and MI and exhibited intermediate properties between the V- and M-types when laterality and correlations to visual and motor space of them were jointly examined. These results suggest that the cortical motor areas contribute to the transformation of coordinates to generate final motor commands.

  5. Bilateral movement training and stroke motor recovery progress: a structured review and meta-analysis.

    Science.gov (United States)

    Cauraugh, James H; Lodha, Neha; Naik, Sagar K; Summers, Jeffery J

    2010-10-01

    The purpose was to conduct a structured review and meta-analysis to determine the cumulative effect of bilateral arm training on motor capabilities post stroke. Forty-eight stroke studies were selected from three databases with 25 comparisons qualifying for inclusion in our meta-analysis. We identified and coded four types of bilateral arm interventions with 366 stroke patients. A random effects model using the standardized mean difference technique determined a large and significant effect size (0.734; SE=0.125), high fail-safe N (532), and medium variability in the studies (I(2)=63%). Moderator variable analysis on the type of bilateral training revealed two large and significant effects: (a) BATRAC (0.842; SE=0.155) and (b) coupled bilateral and EMG-triggered neuromuscular stimulation (1.142; SE=0.176). These novel findings provide strong evidence supporting bilateral arm training with the caveat that two coupled protocols, rhythmic alternating movements and active stimulation, are most effective.

  6. Blood oxygenation-level dependent functional MRI in evaluating the selective activation of motor cortexes associated with recovery of motor function in hemiplegic patients with ischemic stroke

    Institute of Scientific and Technical Information of China (English)

    Yuechun Li; Xiaoyan Liu; Guorong Liu; Ying He; Baojun Wang; Furu Liang; Li Wang; Hui Zhang; Jingfen Zhang; Ruiming Li

    2006-01-01

    an interval of 30 s. Te AVANTO 1.5T MRI machine (Siemens Company, Germany) was used for scanning, the 30 s before fMRI BOLD scanning was the adaptation phase for the patients, and the finger movements were alternated for 6-10 times till the end of the scanning.MAIN OUTCOME MEASURES: Differences after rehabilitation evaluated by the activations of different sensorimotor cortex in the hemiplegic patients with acute stroke. RESULTS: ① In passive and active movements of the affected hand, 5 cases of Brunnstrom grade Ⅰ or Ⅱ were manifested by the activation of unilateral sensorimotor cortex (SMC) of the hemiplegic side, and they were Brunnstrom grade Ⅱ after 3-week rehabilitation, and 1 case with activations of bilateral SMC recovered to Brunnstrom grade Ⅲ. ② Among the patients of Brunnstrom grade Ⅲ or Ⅳ, 5 cases were unilaterally activated, and had no changes after 3-week rehabilitation; Whereas of the 9 cases of bilateral activations, 3 recovered to grade Ⅵ and 6 recovered to grade Ⅴ after 3-week rehabilitation. ③ In the passive and active movements of the affected hand, all the cases of Brunnstrom grades Ⅴ and Ⅵ were manifested by the activations of bilateral SMC. After 3-week rehabilitation, 2 of the 4 cases of grade Ⅴ recovered to grade Ⅵ, and the other 2 recovered to normal; Whereas 5 of the 6 cases of grade Ⅵ recovered to normal, and the other 1 was still grade Ⅵ. CONCLUSION: BOLD fMRI showed that the outcomes of short-term rehabilitation in the patients with bilateral activations were obvious, whereas the outcomes were bad in the patients whose ipsilateral cortexes were activated. The activated signal in ipsilateral or bilateral SMC and the activation of supplementary motor area in active movements were greater than those in the passive ones.

  7. The role of hearing ability and speech distortion in the facilitation of articulatory motor cortex.

    Science.gov (United States)

    Nuttall, Helen E; Kennedy-Higgins, Daniel; Devlin, Joseph T; Adank, Patti

    2017-01-08

    Excitability of articulatory motor cortex is facilitated when listening to speech in challenging conditions. Beyond this, however, we have little knowledge of what listener-specific and speech-specific factors engage articulatory facilitation during speech perception. For example, it is unknown whether speech motor activity is independent or dependent on the form of distortion in the speech signal. It is also unknown if speech motor facilitation is moderated by hearing ability. We investigated these questions in two experiments. We applied transcranial magnetic stimulation (TMS) to the lip area of primary motor cortex (M1) in young, normally hearing participants to test if lip M1 is sensitive to the quality (Experiment 1) or quantity (Experiment 2) of distortion in the speech signal, and if lip M1 facilitation relates to the hearing ability of the listener. Experiment 1 found that lip motor evoked potentials (MEPs) were larger during perception of motor-distorted speech that had been produced using a tongue depressor, and during perception of speech presented in background noise, relative to natural speech in quiet. Experiment 2 did not find evidence of motor system facilitation when speech was presented in noise at signal-to-noise ratios where speech intelligibility was at 50% or 75%, which were significantly less severe noise levels than used in Experiment 1. However, there was a significant interaction between noise condition and hearing ability, which indicated that when speech stimuli were correctly classified at 50%, speech motor facilitation was observed in individuals with better hearing, whereas individuals with relatively worse but still normal hearing showed more activation during perception of clear speech. These findings indicate that the motor system may be sensitive to the quantity, but not quality, of degradation in the speech signal. Data support the notion that motor cortex complements auditory cortex during speech perception, and point to a role

  8. Inflammation and neuronal death in the motor cortex of the wobbler mouse, an ALS animal model

    DEFF Research Database (Denmark)

    Dahlke, Carolin; Saberi, Darius; Ott, Bastian

    2015-01-01

    be an important contributing factor of motor neuron degeneration. This would appear to be confirmed by the fact that there was no conspicuous increase of microglial cells and astrocytes in the motor cortex of control mice at any time. Conclusions Activated microglial cells secrete a variety of pro...

  9. The primary motor and premotor areas of the human cerebral cortex.

    Science.gov (United States)

    Chouinard, Philippe A; Paus, Tomás

    2006-04-01

    Brodmann's cytoarchitectonic map of the human cortex designates area 4 as cortex in the anterior bank of the precentral sulcus and area 6 as cortex encompassing the precentral gyrus and the posterior portion of the superior frontal gyrus on both the lateral and medial surfaces of the brain. More than 70 years ago, Fulton proposed a functional distinction between these two areas, coining the terms primary motor area for cortex in Brodmann area 4 and premotor area for cortex in Brodmann area 6. The parcellation of the cortical motor system has subsequently become more complex. Several nonprimary motor areas have been identified in the brain of the macaque monkey, and associations between anatomy and function in the human brain are being tested continuously using brain mapping techniques. In the present review, the authors discuss the unique properties of the primary motor area (M1), the dorsal portion of the premotor cortex (PMd), and the ventral portion of the premotor cortex (PMv). They end this review by discussing how the premotor areas influence M1.

  10. Long lasting structural changes in primary motor cortex after motor skill learning: a behavioural and stereological study.

    Science.gov (United States)

    Morales, Paola

    2008-01-01

    Many motor skills, once acquired, are stored over a long time period, probably sustained by permanent neuronal changes. Thus, in this paper we have investigated with quantitative stereology the generation and persistence of neuronal density changes in primary motor cortex (MI) following motor skill learning (skilled reaching task). Rats were trained a lateralised reaching task during an "early" (22-31 days old) or "late" (362-371 days old) postnatal period. The trained and corresponding control rats were sacrificed at day 372, immediately after the behavioural testing. The "early" trained group preserved the learned skilled reaching task when tested at day 372, without requiring any additional training. The "late" trained group showed a similar capacity to that of the "early" trained group for learning the skilled reaching task. All trained animals ("early" and "late" trained groups) showed a significant Inter hemispheric decrease of neuronal density in the corresponding motor forelimb representation area of MI (cortical layers II-III). It is concluded that learning a skilled reaching task implies long lasting structural changes in restricted cortical regions of the motor cortex. The generation and persistence of these changes probably reflect a plastic reorganization for storing and retrieving motor skills. The plastic changes were also observed in the older rats, suggesting that motor cortex maintains its plastic capacity throughout the lifespan.

  11. A novel dual-site transcranial magnetic stimulation paradigm to probe fast facilitatory inputs from ipsilateral dorsal premotor cortex to primary motor cortex

    DEFF Research Database (Denmark)

    Groppa, Sergiu; Werner-Petroll, Nicole; Münchau, Alexander

    2012-01-01

    The dorsal premotor cortex (PMd) plays an import role in action control, sensorimotor integration and motor recovery. Animal studies and human data have demonstrated direct connections between ipsilateral PMd and primary motor cortex hand area (M1(HAND)). In this study we adopted a multimodal app...

  12. Cortical spreading depression and involvement of the motor cortex, auditory cortex, and cerebellum in eyeblink classical conditioning of the rabbit.

    Science.gov (United States)

    Case, Gilbert R; Lavond, David G; Thompson, Richard F

    2002-09-01

    The interrelationships of cerebellar and cerebral neural circuits in the eyeblink paradigm were explored with the controlled application of cortical spreading depression (CSD) and lidocaine in the New Zealand albino rabbit. The initial research focus was directed toward the involvement of the motor cortex in the conditioned eyeblink response. However, CSD timing and triangulation results indicate that other areas in the cerebral cortex, particularly the auditory cortex (acoustic conditioned stimulus), appear to be critical for the CSD effect on the eyeblink response. In summary: (1) CSD can be elicited, monitored, and timed and its side effects controlled in 97% of awake rabbits in the right and/or left cerebral hemisphere(s) during eyeblink conditioning. (2) The motor cortex appears to play little or no part in classical conditioning of the eyeblink in the rabbit in the delay paradigm. (3) Inactivating the auditory cortex with CSD or lidocaine temporarily impairs the conditioned response during the first 5 to 15 days of training, but has little effect past that point.

  13. Activation of the motor cortex during phasic rapid eye movement sleep

    Science.gov (United States)

    De Carli, Fabrizio; Proserpio, Paola; Morrone, Elisa; Sartori, Ivana; Ferrara, Michele; Gibbs, Steve Alex; De Gennaro, Luigi; Lo Russo, Giorgio

    2016-01-01

    When dreaming during rapid eye movement (REM) sleep, we can perform complex motor behaviors while remaining motionless. How the motor cortex behaves during this state remains unknown. Here, using intracerebral electrodes sampling the human motor cortex in pharmacoresistant epileptic patients, we report a pattern of electroencephalographic activation during REM sleep similar to that observed during the performance of a voluntary movement during wakefulness. This pattern is present during phasic REM sleep but not during tonic REM sleep, the latter resembling relaxed wakefulness. This finding may help clarify certain phenomenological aspects observed in REM sleep behavior disorder. Ann Neurol 2016;79:326–330 PMID:26575212

  14. Interaction between visual and motor cortex: a transcranial magnetic stimulation study.

    Science.gov (United States)

    Strigaro, Gionata; Ruge, Diane; Chen, Jui-Cheng; Marshall, Louise; Desikan, Mahalekshmi; Cantello, Roberto; Rothwell, John C

    2015-05-15

    The major link between the visual and motor systems is via the dorsal stream pathways from visual to parietal and frontal areas of the cortex. Although the pathway appears to be indirect, there is evidence that visual input can reach the motor cortex at relatively short latency. To shed some light on its neural basis, we studied the visuomotor interaction using paired transcranial magnetic stimulation (TMS). Motor-evoked potentials (MEPs) were recorded from the right first dorsal interosseous in sixteen healthy volunteers. A conditioning stimulus (CS) was applied over the phosphene hotspot of the visual cortex, followed by a test stimulus over the left primary motor cortex (M1) with a random interstimulus interval (ISI) in range 12-40 ms. The effects of paired stimulation were retested during visual and auditory reaction-time tasks (RT). Finally, we measured the effects of a CS on short-interval intracortical inhibition (SICI). At rest, a CS over the occiput significantly (P visual RT, inhibition with an ISI of 40 ms (but not 18 ms) was replaced by a time-specific facilitation (P visual to motor cortices using paired-TMS with an ISI in the range 18-40 ms. The connections are inhibitory at rest and possibly mediated by inhibitory interneurones in the motor cortex. The effect with an ISI of 40 ms reverses into facilitation during a visuomotor RT but not an audiomotor RT. This suggests that it plays a role in visuomotor integration.

  15. Structural damage to the corticospinal tract correlates with bilateral sensorimotor cortex reorganization in stroke patients.

    Science.gov (United States)

    Schaechter, Judith D; Perdue, Katherine L; Wang, Ruopeng

    2008-02-01

    Damage to the corticospinal tract (CST) in stroke patients has been associated with functional reorganization in the ipsilesional and contralesional sensorimotor cortices. However, it is unknown whether a quantitative relationship exists between the extent of structural damage to the CST and functional reorganization in stroke patients. The purpose of the current study was to examine the relationship between structural CST damage and motor task-related cortical activity in chronic hemiparetic stroke patients. In 10 chronic hemiparetic stroke patients with heterogeneous lesions, CST damage was quantified using conventional structural magnetic resonance imaging and tractography based on diffusion tensor imaging. Cortical activity was measured using functional magnetic resonance imaging during repetitive flexion/extension movements of the digits. We found that the two measures of CST damage were strongly correlated. Moreover, greater CST damage was significantly and linearly correlated with increased activation during affected hand movement in the hand area of the contralesional primary sensorimotor cortex (M1/S1) and in the ipsilesional M1/S1 ventral to the hand area. To our knowledge, this is the first demonstration of a quantitative relationship between the extent of structural damage to the CST and functional reorganization in stroke patients. This relationship was observed in stroke patients with heterogeneous lesions, suggesting that CST damage is a factor relevant to the variation in functional reorganization in the clinical population.

  16. Task-dependent engagements of the primary visual cortex during kinesthetic and visual motor imagery.

    Science.gov (United States)

    Mizuguchi, Nobuaki; Nakamura, Maiko; Kanosue, Kazuyuki

    2017-01-01

    Motor imagery can be divided into kinesthetic and visual aspects. In the present study, we investigated excitability in the corticospinal tract and primary visual cortex (V1) during kinesthetic and visual motor imagery. To accomplish this, we measured motor evoked potentials (MEPs) and probability of phosphene occurrence during the two types of motor imageries of finger tapping. The MEPs and phosphenes were induced by transcranial magnetic stimulation to the primary motor cortex and V1, respectively. The amplitudes of MEPs and probability of phosphene occurrence during motor imagery were normalized based on the values obtained at rest. Corticospinal excitability increased during both kinesthetic and visual motor imagery, while excitability in V1 was increased only during visual motor imagery. These results imply that modulation of cortical excitability during kinesthetic and visual motor imagery is task dependent. The present finding aids in the understanding of the neural mechanisms underlying motor imagery and provides useful information for the use of motor imagery in rehabilitation or motor imagery training.

  17. Timing-dependent modulation of the posterior parietal cortex-primary motor cortex pathway by sensorimotor training

    DEFF Research Database (Denmark)

    Karabanov, Anke; Jin, Seung-Hyun; Joutsen, Atte

    2012-01-01

    Interplay between posterior parietal cortex (PPC) and ipsilateral primary motor cortex (M1) is crucial during execution of movements. The purpose of the study was to determine whether functional PPC-M1 connectivity in humans can be modulated by sensorimotor training. Seventeen participants...... performed a sensorimotor training task that involved tapping the index finger in synchrony to a rhythmic sequence. To explore differences in training modality, one group (n = 8) learned by visual and the other (n = 9) by auditory stimuli. Transcranial magnetic stimulation (TMS) was used to assess PPC-M1...

  18. Contribution of the resting-state functional connectivity of the contralesional primary sensorimotor cortex to motor recovery after subcortical stroke.

    Directory of Open Access Journals (Sweden)

    Huijuan Xu

    Full Text Available It remains uncertain if the contralesional primary sensorimotor cortex (CL_PSMC contributes to motor recovery after stroke. Here we investigated longitudinal changes in the resting-state functional connectivity (rsFC of the CL_PSMC and their association with motor recovery. Thirteen patients who had experienced subcortical stroke underwent a series of resting-state fMRI and clinical assessments over a period of 1 year at 5 time points, i.e., within the first week, at 2 weeks, 1 month, 3 months, and 1 year after stroke onset. Thirteen age- and gender-matched healthy subjects were recruited as controls. The CL_PSMC was defined as a region centered at the voxel that had greatest activation during hand motion task. The dynamic changes in the rsFCs of the CL_PSMC within the whole brain were evaluated and correlated with the Motricity Index (MI scores. Compared with healthy controls, the rsFCs of the CL_PSMC with the bilateral PSMC were initially decreased, then gradually increased, and finally restored to the normal level 1 year later. Moreover, the dynamic change in the inter-hemispheric rsFC between the bilateral PSMC in these patients was positively correlated with the MI scores. However, the intra-hemispheric rsFC of the CL_PSMC was not correlated with the MI scores. This study shows dynamic changes in the rsFCs of the CL_PSMC after stroke and suggests that the increased inter-hemispheric rsFC between the bilateral PSMC may facilitate motor recovery in stroke patients. However, generalization of our findings is limited by the small sample size of our study and needs to be confirmed.

  19. The Neural Mechanism Exploration of Adaptive Motor Control: Dynamical Economic Cell Allocation in the Primary Motor Cortex.

    Science.gov (United States)

    Li, Wei; Guo, Yangyang; Fan, Jing; Ma, Chaolin; Ma, Xuan; Chen, Xi; He, Jiping

    2017-05-01

    Adaptive flexibility is of significance for the smooth and efficient movements in goal attainment. However, the underlying work mechanism of the cerebral cortex in adaptive motor control still remains unclear. How does the cerebral cortex organize and coordinate the activity of a large population of cells in the implementation of various motor strategies? To explore this issue, single-unit activities from the M1 region and kinematic data were recorded simultaneously in monkeys performing 3D reach-to-grasp tasks with different perturbations. Varying motor control strategies were employed and achieved in different perturbed tasks, via the dynamic allocation of cells to modulate specific movement parameters. An economic principle was proposed for the first time to describe a basic rule for cell allocation in the primary motor cortex. This principle, defined as the Dynamic Economic Cell Allocation Mechanism (DECAM), guarantees benefit maximization in cell allocation under limited neuronal resources, and avoids committing resources to uneconomic investments for unreliable factors with no or little revenue. That is to say, the cells recruited are always preferentially allocated to those factors with reliable return; otherwise, the cells are dispatched to respond to other factors about task. The findings of this study might partially reveal the working mechanisms underlying the role of the cerebral cortex in adaptive motor control, wherein is also of significance for the design of future intelligent brain-machine interfaces and rehabilitation device.

  20. Measurement of motor evoked potentials following repetitive magnetic motor cortex stimulation during isoflurane or propofol anaesthesia.

    Science.gov (United States)

    Rohde, V; Krombach, G A; Baumert, J H; Kreitschmann-Andermahr, I; Weinzierl, M; Gilsbach, J M

    2003-10-01

    Isoflurane and propofol reduce the recordability of compound muscle action potentials (CMAP) following single transcranial magnetic stimulation of the motor cortex (sTCMS). Repetition of the magnetic stimulus (repetitive transcranial magnetic stimulation, rTCMS) might allow the inhibition caused by anaesthesia with isoflurane or propofol to be overcome. We applied rTCMS (four stimuli; inter-stimulus intervals of 3, 4, 5 ms (333, 250, 200 Hz), output 2.5 Tesla) in 27 patients and recorded CMAP from the hypothenar and anterior tibial muscle. Anaesthesia was maintained with fentanyl 0.5-1 microg kg(-1) x h(-1) and either isoflurane 1.2% (10 patients) or propofol 5 mg kg(-1) x h(-1) with nitrous oxide 60% in oxygen (17 patients). No CMAP were detected during isoflurane anaesthesia. During propofol anaesthesia 333 Hz, four-pulse magnetic stimulation evoked CMAP in the hypothenar muscle in 75%, and in the anterior tibial muscle in 65% of the patients. Less response was obtained with 250 and 200 Hz stimulation. In most patients, rTCMS can overcome suppression of CMAP during propofol/nitrous oxide anaesthesia, but not during isoflurane anaesthesia. A train of four magnetic stimuli at a frequency of 333 Hz is most effective in evoking potentials from the upper and lower limb muscles. The authors conclude that rTCMS can be used for evaluation of the descending motor pathways during anaesthesia.

  1. Reduced inhibition within primary motor cortex in patients with poststroke focal motor seizures.

    Science.gov (United States)

    Kessler, Kirn R; Schnitzler, Alfons; Classen, Joseph; Benecke, Reiner

    2002-10-08

    Following an ischemic brain lesion, the affected cortex undergoes structural and functional changes that may lead to increased cortical excitability or decreased inhibitory neuronal activity, resulting in the occurrence of poststroke epileptic seizures in 6 to 10% of patients with stroke. To assess motor cortical excitability, transcranial magnetic stimulation (TMS) was used to determine the silent period (SP) duration in 84 consecutive patients with ischemic stroke. In a subpopulation of six patients (38 to 72 years old) a significant decrease of the SP duration (mean 116 +/- 14 msec) was detected in either the arm or the leg on the affected side as compared to the corresponding unaffected limb (mean 231 +/- 32 msec). This electrophysiologic abnormality was clinically associated with focal motor seizures in five of the six patients, whereas none of the other 76 patients with normal or prolonged SP durations developed seizures or epilepsy. Silent period shortening in this group reflects decreased inhibitory activity that may partly be related to functional or structural impairment of GABAergic interneurons. TMS may be of value for determining patients with stroke at risk for developing poststroke seizures.

  2. A change in injured corticospinal tract originating from the premotor cortex to the primary motor cortex in a patient with intracerebral hemorrhage

    Institute of Scientific and Technical Information of China (English)

    Sang Seok Yeo; Sung Ho Jang

    2012-01-01

    Many studies have attempted to elucidate the motor recovery mechanism of stroke, but the majority of these studies focus on cerebral infarct and relatively little is known about the motor recovery mechanism of intracerebral hemorrhage. In this study, we report on a patient with intracerebral hemorrhage who displayed a change in injured corticospinal tract originating from the premotor cortex to the primary motor cortex on diffusion tensor imaging. An 86-year-old woman presented with complete paralysis of the right extremities following spontaneous intracerebral hemorrhage in the left frontoparietal cortex. The patient showed motor recovery, to the extent of being able to extend affected fingers against gravity and to walk independently on even ground at 5 months after onset. Diffusion tensor imaging showed that the left corticospinal tract originated from the premotor cortex at 1 month after intracerebral hemorrhage and from the left primary motor cortex and premotor cortex at 5 months after intracerebral hemorrhage. The change of injured corticospinal tract originating from the premotor cortex to the primary motor cortex suggests motor recovery of intracerebral hemorrhage.

  3. Clinical functional MRI of sensorimotor cortex using passive motor and sensory stimulation at 3 Tesla.

    Science.gov (United States)

    Blatow, Maria; Reinhardt, Julia; Riffel, Katharina; Nennig, Ernst; Wengenroth, Martina; Stippich, Christoph

    2011-08-01

    To establish a passive motor paradigm for clinical functional MRI (fMRI) that could be beneficial for patients with motor or attention deficits who are not able to perform active motor tasks. A novel standardized sensorimotor fMRI protocol was applied in 16 healthy volunteers at 3 Tesla (T) using active and passive motor tasks as well as sensory stimulation of hands and feet. Data analysis was carried out individually using a dynamic thresholding routine. Active motor tasks yielded time efficient and robust blood-oxygen-level-dependent (BOLD) signals in primary motor cortex. Noteworthy, it was possible to achieve equal activation levels within identical anatomical localization for passive and active motor tasks with these paradigms. Patients unable to perform active movements can benefit from paradigms with passive motor and sensory stimulation. Therefore, we recommend these paradigms for functional somatotopic mapping of the central region at 3T in clinical routine. Copyright © 2011 Wiley-Liss, Inc.

  4. Bilateral lesions in a specific subregion of posterior insular cortex impair conditioned taste aversion expression in rats.

    Science.gov (United States)

    Schier, Lindsey A; Blonde, Ginger D; Spector, Alan C

    2016-01-01

    The gustatory cortex (GC) is widely regarded for its integral role in the acquisition and retention of conditioned taste aversions (CTAs) in rodents, but large lesions in this area do not always result in CTA impairment. Recently, using a new lesion mapping system, we found that severe CTA expression deficits were associated with damage to a critical zone that included the posterior half of GC in addition to the insular cortex (IC) that is just dorsal and caudal to this region (visceral cortex). Lesions in anterior GC were without effect. Here, neurotoxic bilateral lesions were placed in the anterior half of this critical damage zone, at the confluence of the posterior GC and the anterior visceral cortex (termed IC2 ), the posterior half of this critical damage zone that contains just VC (termed IC3), or both of these subregions (IC2 + IC3). Then, pre- and postsurgically acquired CTAs (to 0.1 M NaCl and 0.1 M sucrose, respectively) were assessed postsurgically in 15-minute one-bottle and 96-hour two-bottle tests. Li-injected rats with histologically confirmed bilateral lesions in IC2 exhibited the most severe CTA deficits, whereas those with bilateral lesions in IC3 were relatively normal, exhibiting transient disruptions in the one-bottle sessions. Groupwise lesion maps showed that CTA-impaired rats had more extensive damage to IC2 than did unimpaired rats. Some individual differences in CTA expression among rats with similar lesion profiles were observed, suggesting idiosyncrasies in the topographic representation of information in the IC. Nevertheless, this study implicates IC2 as the critical zone of the IC for normal CTA expression.

  5. A dendritic mechanism for decoding traveling waves: principles and applications to motor cortex.

    Directory of Open Access Journals (Sweden)

    Stewart Heitmann

    2013-10-01

    Full Text Available Traveling waves of neuronal oscillations have been observed in many cortical regions, including the motor and sensory cortex. Such waves are often modulated in a task-dependent fashion although their precise functional role remains a matter of debate. Here we conjecture that the cortex can utilize the direction and wavelength of traveling waves to encode information. We present a novel neural mechanism by which such information may be decoded by the spatial arrangement of receptors within the dendritic receptor field. In particular, we show how the density distributions of excitatory and inhibitory receptors can combine to act as a spatial filter of wave patterns. The proposed dendritic mechanism ensures that the neuron selectively responds to specific wave patterns, thus constituting a neural basis of pattern decoding. We validate this proposal in the descending motor system, where we model the large receptor fields of the pyramidal tract neurons - the principle outputs of the motor cortex - decoding motor commands encoded in the direction of traveling wave patterns in motor cortex. We use an existing model of field oscillations in motor cortex to investigate how the topology of the pyramidal cell receptor field acts to tune the cells responses to specific oscillatory wave patterns, even when those patterns are highly degraded. The model replicates key findings of the descending motor system during simple motor tasks, including variable interspike intervals and weak corticospinal coherence. By additionally showing how the nature of the wave patterns can be controlled by modulating the topology of local intra-cortical connections, we hence propose a novel integrated neuronal model of encoding and decoding motor commands.

  6. Long-lasting contralateral motor cortex excitability is increased by unilateral hand movement that triggers electrical stimulation of opposite homologous muscles.

    Science.gov (United States)

    Schmidt, Matthew W; Hinder, Mark R; Summers, Jeffery J; Garry, Michael I

    2011-01-01

    Long-term changes in the motor cortex can be induced by practicing motor tasks with simultaneous application of peripheral nerve stimulation. This combination may augment motor rehabilitation after stroke but has been used primarily during contraction of the affected hand. The authors tested the effect of a right hand movement that electrically stimulated left hand contraction on right motor cortex excitability. Three tasks were used in 15 healthy subjects--a motor and stimulation task (MS(task)), stimulation only task (S(task)), and motor only task (M(task)). The MS(task) consisted of isometric thumb abduction of the right hand that triggered paired electrical stimulation of the left abductor pollicis brevis (APB) and first dorsal interosseus (FDI) motor points. The S(task) was performed 1 week later and matched the stimulation received in the MS(task). The M(task) was performed as a control. Transcranial magnetic stimulation applied to the right motor cortex assessed corticospinal excitability, short latency intracortical inhibition, and intracortical facilitation of the FDI and APB before, immediately after, and 30 minutes after task performance. Corticospinal excitability increased in the FDI and APB following the MS(task) but not following the S(task) or M(task). The increased excitability present 30 minutes after the MS(task) also correlated with excitability measures recorded 1 week later. A bilateral motor and electrical stimulation task can drive persistent adaptation within the corticospinal system. Hemiplegic subjects who have poor voluntary movement of the affected hand may be able to contract the unaffected hand to activate and train homologous movements.

  7. Results by motor cortex stimulation in treatment of focal dystonia, Parkinson's disease and post-ictal spasticity. The experience of the Italian Study Group of the Italian Neurosurgical Society.

    Science.gov (United States)

    Pagni, C A; Albanese, A; Bentivoglio, A; Broggi, G; Canavero, S; Cioni, B; Rose, M D; Simone, C D; Franzini, A; Lavano, A; Landi, A; Meglio, M; Modugno, M; Romanelli, L; Romito, L M; Sturiale, C; Valzania, F; Zeme, S; Zenga, F

    2008-01-01

    Extradural motor cortex stimulation has been employed in cases of Parkinson's disease (PD), fixed dystonia (FD) and spastic hemiparesis (SH) following cerebral stroke. Symptoms of PD are improved by EMCS: results were evaluated on the basis of the UPDRS and statistically analysed. In PD EMCS is less efficacious than bilateral subthalamic nucleus (STN) stimulation, but it may be safely employed in patients not eligible for deep brain stimulation (DBS). The most rewarding effect is the improvement, in severely affected patients, of posture and gait. FD, unresponsive to bilateral pallidal stimulation, has been relieved by EDMS. In SH reduction of spasticiy by EMCS allows improvement of the motor function.

  8. Differential grey matter changes in sensorimotor cortex related to exceptional fine motor skills.

    Directory of Open Access Journals (Sweden)

    M Cornelia Stoeckel

    Full Text Available Functional changes in sensorimotor representation occur in response to use and lesion throughout life. Emerging evidence suggests that functional changes are paralleled by respective macroscopic structural changes. In the present study we used voxel-based morphometry to investigate sensorimotor cortex in subjects with congenitally malformed upper extremities. We expected increased or decreased grey matter to parallel the enlarged or reduced functional representations we reported previously. More specifically, we expected decreased grey matter values in lateral sensorimotor cortex related to compromised hand function and increased grey matter values in medial sensorimotor cortex due to compensatory foot use. We found a medial cluster of grey matter increase in subjects with frequent, hand-like compensatory foot use. This increase was predominantly seen for lateral premotor, supplementary motor, and motor areas and only marginally involved somatosensory cortex. Contrary to our expectation, subjects with a reduced number of fingers, who had shown shrinkage of the functional hand representation previously, did not show decreased grey matter values within lateral sensorimotor cortex. Our data suggest that functional plastic changes in sensorimotor cortex can be associated with increases in grey matter but may also occur in otherwise macroscopically normal appearing grey matter volumes. Furthermore, macroscopic structural changes in motor and premotor areas may be observed without respective changes in somatosensory cortex.

  9. Differential grey matter changes in sensorimotor cortex related to exceptional fine motor skills.

    Science.gov (United States)

    Stoeckel, M Cornelia; Morgenroth, Farina; Buetefisch, Cathrin M; Seitz, Rüdiger J

    2012-01-01

    Functional changes in sensorimotor representation occur in response to use and lesion throughout life. Emerging evidence suggests that functional changes are paralleled by respective macroscopic structural changes. In the present study we used voxel-based morphometry to investigate sensorimotor cortex in subjects with congenitally malformed upper extremities. We expected increased or decreased grey matter to parallel the enlarged or reduced functional representations we reported previously. More specifically, we expected decreased grey matter values in lateral sensorimotor cortex related to compromised hand function and increased grey matter values in medial sensorimotor cortex due to compensatory foot use. We found a medial cluster of grey matter increase in subjects with frequent, hand-like compensatory foot use. This increase was predominantly seen for lateral premotor, supplementary motor, and motor areas and only marginally involved somatosensory cortex. Contrary to our expectation, subjects with a reduced number of fingers, who had shown shrinkage of the functional hand representation previously, did not show decreased grey matter values within lateral sensorimotor cortex. Our data suggest that functional plastic changes in sensorimotor cortex can be associated with increases in grey matter but may also occur in otherwise macroscopically normal appearing grey matter volumes. Furthermore, macroscopic structural changes in motor and premotor areas may be observed without respective changes in somatosensory cortex.

  10. The cortical activation pattern during bilateral arm raising movements

    Science.gov (United States)

    Jang, Sung Ho; Seo, Jung Pyo; Lee, Seung-Hyun; Jin, Sang-Hyun; Yeo, Sang Seok

    2017-01-01

    Bilateral arm raising movements have been used in brain rehabilitation for a long time. However, no study has been reported on the effect of these movements on the cerebral cortex. In this study, using functional near infrared spectroscopy (fNIRS), we attempted to investigate cortical activation generated during bilateral arm raising movements. Ten normal subjects were recruited for this study. fNIRS was performed using an fNIRS system with 49 channels. Bilateral arm raising movements were performed in sitting position at the rate of 0.5 Hz. We measured values of oxyhemoglobin and total hemoglobin in five regions of interest: the primary sensorimotor cortex, premotor cortex, supplementary motor area, prefrontal cortex, and posterior parietal cortex. During performance of bilateral arm raising movements, oxyhemoglobin and total hemoglobin values in the primary sensorimotor cortex, premotor cortex, supplementary motor area, and prefrontal cortex were similar, but higher in these regions than those in the prefrontal cortex. We observed activation of the arm somatotopic areas of the primary sensorimotor cortex and premotor cortex in both hemispheres during bilateral arm raising movements. According to this result, bilateral arm raising movements appeared to induce large-scale neuronal activation and therefore arm raising movements would be good exercise for recovery of brain functions. PMID:28400816

  11. Cortical stimulation for central neuropathic pain: 3-D surface MRI for easy determination of the motor cortex.

    Science.gov (United States)

    Herregodts, P; Stadnik, T; De Ridder, F; D'Haens, J

    1995-01-01

    Motor cortex electric stimulation has been reported to be effective for the treatment of central post-stroke pain and trigeminal neuropathic pain. Five patients with pain due to injury of the trigeminal nerve and with abnormalities of facial sensibility, as well as two patients suffering of a post-stroke thalamic pain, were subjected to stimulation applied epidurally on the motor cortex. Quadripolar electrodes were implanted under local anaesthesia and the precise location of the motor cortex was determined on three-dimensional surface MRI the day prior to surgery. In our experience, correct topographic localization of the electrode on the motor cortex seems to be crucial to obtain pain reduction.

  12. Action Verbs and the Primary Motor Cortex: A Comparative TMS Study of Silent Reading, Frequency Judgments, and Motor Imagery

    Science.gov (United States)

    Tomasino, Barbara; Fink, Gereon R.; Sparing, Roland; Dafotakis, Manuel; Weiss, Peter H.

    2008-01-01

    Single pulse transcranial magnetic stimulation (TMS) was applied to the hand area of the left primary motor cortex or, as a control, to the vertex (STIMULATION: TMS[subscript M1] vs. TMS[subscript vertex]) while right-handed volunteers silently read verbs related to hand actions. We examined three different tasks and time points for stimulation…

  13. A Study on a Brain-Computer Interface for Motor Assist by Prefrontal Cortex

    Science.gov (United States)

    Misawa, Tadanobu; Takano, Shinya; Shimokawa, Tetsuya; Hirobayashi, Shigeki

    In recent times, considerable research has been conducted on the development of brain-computer interfaces (BCIs). Although there have been several reports on BCIs that assist motor functions by measurement of brain activity in the motor cortex, only a few studies have reported on BCI that assist motor functions by measurement of activity in areas other than the motor cortex. In this study, we experimentally develop a BCI that assists motor functions on the basis of brain activity in the prefrontal cortex. In this BCI system, subjects are shown the labyrinth problem. Concretely, brain activity is measured using fNIRS and the data are acquired in real time. The signal processing module implements low pass filtering of these signals. Further, the pattern classification module used in this system currently is a support vector machine. 22 subjects, both male and female, volunteered to participate in this experiment. 8 of these 22 subjects were able to solve the labyrinth problem. In this experiment, we could not obtain a high distinction. However, these results show that it is possible to develop BCI systems that assist motor functions using information from the prefrontal cortex.

  14. Observation of activation status of motor-related cortex of patients with acute ischemic stroke through functional magnetic resonance imaging

    Institute of Scientific and Technical Information of China (English)

    Ziqian Chen; Hui Xiao; Ping Ni; Gennian Qian; Shangwen Xu; Xizhang Yang; Youqiang Ye; Jinhua Chen; Biyun Zhang

    2006-01-01

    magnetic resonance imaging system. All the data were given off-line management, and fMRI was treated with SPM2 software. The activation of passive finger-to-finger motion-related cortex of subjects in 2 groups was observed. ③ Results of fMRI of subjects in 2 groups were compared. The size of activation region of brain and signal intensity were measured and unilateral index was calculated. The data of activation region of cerebral hemisphere of different sides at finger motion were given statistical analysis of unilateral index. Differences among unilateral indexes at hand motion were compared between intact and affected hands of patients in experimental group. The relationship between unilateral index and muscular strength of affected hands at affected hand motion in patients of the experimental group was performed Spearman correlation analysis.MAIN OUTCOME MEASURES: ① The activation of motion-related cortex passive finger-to-finger motion between handedness and non-handedness was detected with functional magnetic resonance imaging of subjects in 2 groups. ② Relationship between unilateral index and muscular strength of subjects of experimental group at affected hand motion.RESULTS: Nine patients with ischemic stroke and 9 controls all participated in the final result analysis. ① Passive fMRI detection results between handedness and non-handedness of controls: Right-handed finger-to-finger motion of subjects of control group mainly activated contralateral sensorimotor cortex, and left-handed finger-to-finger motion not only activated above-mentioned brain region, but also activated supplementary motor area (SMA) of contralateral brain region; ② ln the experimental group, sensorimotor cortex of contralateral hemisphere was activated at affected hand motion, and homolateral posterior parietal cortex (PPC)was also obviously activated. Bilateral sensorimotor cortex was activated at affected hand motion in 2 patients, and homolateral activation area was larger than

  15. [Participation of the primary motor cortex in programming of muscle activity during catching of falling object].

    Science.gov (United States)

    Kazennikov, O V; Lipshits, M I

    2011-01-01

    Object fell into the cup that sitting subject held between thumb and index fingers. Transcranial magnetic stimulation (TMS) of the primary motor cortex was performed early before and during anticipatory grip force increasing. Comparison of current EMG activity of adductor pollicis brevis and first dorsal interosseous muscles and responses of these muscles on TMS showed that responses were increased before the raising of muscle activity. From the other side only slight augmentation of responses was observed during subsequent strong muscle activation. It is assumed that the increasing of the TMS responses that occurred before the initiation of muscle activity reflects the enhancement ofthe motor cortex excitability associated to specific processes related to the motor cortex participation in programming of the muscles activities.

  16. Motor Cortex Plasticity during Unilateral Finger Movement with Mirror Visual Feedback

    Directory of Open Access Journals (Sweden)

    Hatice Kumru

    2016-01-01

    Full Text Available Plasticity is one of the most important physiological mechanisms underlying motor recovery from brain lesions. Rehabilitation methods, such as mirror visual feedback therapy, which are based on multisensory integration of motor, cognitive, and perceptual processes, are considered effective methods to induce cortical reorganization. The present study investigated 3 different types of visual feedback (direct, mirrored, and blocked visual feedback: DVF, MVF, and BVF, resp. on M1 cortex excitability and intracortical inhibition/facilitation at rest and during phasic unimanual motor task in 11 healthy individuals. The excitability of the ipsilateral M1 cortex and the intracortical facilitation increased during motor task performance in the DVF and MVF but not in the BVF condition. In addition, MVF induced cortical disinhibition of the ipsilateral hemisphere to the index finger performing the motor task, which was greater when compared to the BVF and restricted to the homologue first dorsal interosseous muscle. The visual feedback is relevant to M1 cortex excitability modulation but the MVF plays a crucial role in promoting changes in intracortical inhibition in comparison to BVF. Altogether, it can be concluded that a combination of motor training with MVF therapy may induce more robust neuroplastic changes through multisensory integration that is relevant to motor rehabilitation.

  17. Motor Cortex Activity Organizes the Developing Rubrospinal System.

    Science.gov (United States)

    Williams, Preston T J A; Martin, John H

    2015-09-30

    The corticospinal and rubrospinal systems function in skilled movement control. A key question is how do these systems develop the capacity to coordinate their motor functions and, in turn, if the red nucleus/rubrospinal tract (RN/RST) compensates for developmental corticospinal injury? We used the cat to investigate whether the developing rubrospinal system is shaped by activity-dependent interactions with the developing corticospinal system. We unilaterally inactivated M1 by muscimol microinfusion between postnatal weeks 5 and 7 to examine activity-dependent interactions and whether the RN/RST compensates for corticospinal tract (CST) developmental motor impairments and CST misprojections after M1 inactivation. We examined the RN motor map and RST cervical projections at 7 weeks of age, while the corticospinal system was inactivated, and at 14 weeks, after activity returned. During M1 inactivation, the RN on the same side showed normal RST projections and reduced motor thresholds, suggestive of precocious development. By contrast, the RN on the untreated/active M1 side showed sparse RST projections and an immature motor map. After M1 activity returned later in adolescent cat development, RN on the active M1/CST side continued to show a substantial loss of spinal terminations and an impaired motor map. RN/RST on the inactivated side regressed to a smaller map and fewer axons. Our findings suggest that the developing rubrospinal system is under activity-dependent regulation by the corticospinal system for establishing mature RST connections and RN motor map. The lack of RS compensation on the non-inactivated side can be explained by development of ipsilateral misprojections from the active M1 that outcompete the RST. Significance statement: Skilled movements reflect the activity of multiple descending motor systems and their interactions with spinal motor circuits. Currently, there is little insight into whether motor systems interact during development to

  18. Homuncular organization of human motor cortex as indicated by neuromagnetic recordings.

    Science.gov (United States)

    Cheyne, D; Kristeva, R; Deecke, L

    1991-01-14

    Sources of neural activity identified using non-invasive measurements of cerebral magnetic fields (magnetoencephalography) were found to confirm the somatotopic organization of primary motor cortex for movements of different parts of the body in normal human subjects. Somatotopic maps produced with this technique showed slight differences to the 'classic' homunculus obtained from studies using direct cortical stimulation. These findings indicate that neuromagnetic recordings are capable of localizing cortical activity associated with voluntarily produced movements without the use of external stimulation and provide a new method for studying the functional organization of human motor cortex and its role in voluntary movement.

  19. Modulation of motor cortex excitability by physical similarity with an observed hand action.

    Directory of Open Access Journals (Sweden)

    Marie-Christine Désy

    Full Text Available The passive observation of hand actions is associated with increased motor cortex excitability, presumably reflecting activity within the human mirror neuron system (MNS. Recent data show that in-group ethnic membership increases motor cortex excitability during observation of culturally relevant hand gestures, suggesting that physical similarity with an observed body part may modulate MNS responses. Here, we ask whether the MNS is preferentially activated by passive observation of hand actions that are similar or dissimilar to self in terms of sex and skin color. Transcranial magnetic stimulation-induced motor evoked potentials were recorded from the first dorsal interosseus muscle while participants viewed videos depicting index finger movements made by female or male participants with black or white skin color. Forty-eight participants equally distributed in terms of sex and skin color participated in the study. Results show an interaction between self-attributes and physical attributes of the observed hand in the right motor cortex of female participants, where corticospinal excitability is increased during observation of hand actions in a different skin color than that of the observer. Our data show that specific physical properties of an observed action modulate motor cortex excitability and we hypothesize that in-group/out-group membership and self-related processes underlie these effects.

  20. Evidence against a single coordinate system representation in the motor cortex.

    Science.gov (United States)

    Wu, Wei; Hatsopoulos, Nicholas

    2006-11-01

    Understanding the coordinate systems in which the motor cortical cells encode movement parameters such as direction is a fundamental yet unresolved issue. Although many studies have assumed that motor cortex encodes direction in an extrinsic, Cartesian (CA) coordinate system, other studies have provided evidence for encoding in intermediate coordinate systems such as a shoulder-centered (SC) or in a purely intrinsic, joint-angle-based (JA) coordinate frame. By simultaneously recording from multiple single units in primary motor cortex, we examined movement direction encoding under each of these three coordinate systems. We directly compared the degree of directional tuning invariance over multiple sub-regions in the workspace. We also compared the mutual information between neuronal firing rate and movement direction in the three systems. We observed a broad range of directional invariance in all three coordinate systems with no strong dominance of any single coordinate system. The mutual information analyses corroborated this observation. However, we found a small but significant bias toward the SC coordinate frame, which was also supported by population vector decoding. Similar results were found when we compared hand/torque force direction encoding in all three coordinate systems. These results suggest that the motor cortex employs a coordinate system that is yet to be discovered or perhaps that the motor cortex should not be viewed as a substrate for any coordinate system representation.

  1. Influence of position and stimulation parameters on intracortical inhibition and facilitation in human tongue motor cortex

    DEFF Research Database (Denmark)

    Kothari, Mohit; Svensson, Peter; Nielsen, Jørgen Feldbæk;

    stimulus (TS) and conditioning stimulus (CS) and intensities of the TS and CS on the degree of SICI and ICF. In study 1 and 2, fourteen and seventeen healthy volunteers participated respectively. ppTMS was applied over the “hot-spot” of the tongue motor cortex and motor evoked potentials (MEPs) were...... recorded from contralateral tongue muscles. In study 1, single pulse and three ppTMS ISIs: 2, 10, 15 ms were applied 8 times each in three blocks (TS: 120%, 140% and 160% of resting motor threshold (rMT); CS: 80% of rMT) in two different body positions (recline and supine) randomly. In study 2, single.......042) in study 1. In study 2, there was a significant effect of ISI (Ptongue training on SICI and ICF in the tongue motor cortex....

  2. Assignment Confidence in Localization of the Hand Motor Cortex: Comparison of Structural Imaging With Functional MRI.

    Science.gov (United States)

    Sahin, Neslin; Mohan, Suyash; Maralani, Pejman J; Duddukuri, Srikalyan; O'Rourke, Donald M; Melhem, Elias R; Wolf, Ronald L

    2016-12-01

    The purpose of this study was to assign confidence levels to structural MRI and functional MRI (fMRI) for localization of the primary motor cortex. Ninety-one fMRI studies with at least one motor task (178 hemispheres) were identified. Three anatomic assessments were used to localize the primary motor cortex: relation between the superior frontal sulcus and precentral sulcus; cortical thickness; and configuration of the precentral knob. In 105 hemispheres, interreader agreement was assessed for two investigators with different experience levels. Confidence ratings from 0 to 5 (0, no confidence; 5, 100% confidence) were assigned for fMRI and each anatomic localization method. Cortical thickness had the highest confidence rating (mean, 4.90 ± 0.47 [SD]) with only one failure. The relation between the superior frontal sulcus and precentral sulcus had the lowest confidence rating (4.33 ± 0.91) with three failures. The greatest statistical significance was observed for the cortical thickness and superior frontal sulcus-precentral sulcus methods (post hoc Bonferroni test, p Confidence rating scores were significantly higher for the cortical thickness sign than for fMRI results (4.72 ± 0.54) for a single motor task (post hoc Bonferroni test, p = 0.006); however, the mean confidence rating for fMRI improved to 4.87 ± 0.36 when additional motor tasks were performed. Interreader differences were least for the cortical thickness sign (paired t test, t = 4.25, p confidence regarding localization of the primary motor cortex; however, localization of motor function is more specific when combined with fMRI findings. Multiple techniques can be used to increase confidence in identifying the hand motor cortex.

  3. Current direction specificity of continuous θ-burst stimulation in modulating human motor cortex excitability when applied to somatosensory cortex.

    Science.gov (United States)

    Jacobs, Mark F; Zapallow, Christopher M; Tsang, Philemon; Lee, Kevin G H; Asmussen, Michael J; Nelson, Aimee J

    2012-11-14

    The present study examines the influence of primary somatosensory cortex (SI) on corticospinal excitability within primary motor cortex (M1) using repetitive transcranial magnetic stimulation. Two groups of subjects participated and both received continuous theta-burst stimulation (cTBS) over SI. One group received cTBS oriented to induce anterior-to-posterior (AP) followed by posterior-to-anterior (PA) current flow in the cortex and the other group received cTBS in the opposite direction (PA-AP). Motor evoked potentials (MEPs) were measured from the first dorsal interosseous muscle of the left and right hand before and at three time points (5, 25, 45 min) following cTBS over left-hemisphere SI. CTBS over SI in the AP-PA direction increased contralateral MEPs at 5 and 45 min with a near significant increase at 25 min. In contrast, PA-AP cTBS decreased contralateral MEPs at 25 min. We conclude that cTBS over SI modulates neural output directed to the hand with effects that depend on the direction of induced current.

  4. Effects of TMS on different stages of motor and non-motor verb processing in the primary motor cortex.

    Directory of Open Access Journals (Sweden)

    Liuba Papeo

    Full Text Available The embodied cognition hypothesis suggests that motor and premotor areas are automatically and necessarily involved in understanding action language, as word conceptual representations are embodied. This transcranial magnetic stimulation (TMS study explores the role of the left primary motor cortex in action-verb processing. TMS-induced motor-evoked potentials from right-hand muscles were recorded as a measure of M1 activity, while participants were asked either to judge explicitly whether a verb was action-related (semantic task or to decide on the number of syllables in a verb (syllabic task. TMS was applied in three different experiments at 170, 350 and 500 ms post-stimulus during both tasks to identify when the enhancement of M1 activity occurred during word processing. The delays between stimulus onset and magnetic stimulation were consistent with electrophysiological studies, suggesting that word recognition can be differentiated into early (within 200 ms and late (within 400 ms lexical-semantic stages, and post-conceptual stages. Reaction times and accuracy were recorded to measure the extent to which the participants' linguistic performance was affected by the interference of TMS with M1 activity. No enhancement of M1 activity specific for action verbs was found at 170 and 350 ms post-stimulus, when lexical-semantic processes are presumed to occur (Experiments 1-2. When TMS was applied at 500 ms post-stimulus (Experiment 3, processing action verbs, compared with non-action verbs, increased the M1-activity in the semantic task and decreased it in the syllabic task. This effect was specific for hand-action verbs and was not observed for action-verbs related to other body parts. Neither accuracy nor RTs were affected by TMS. These findings suggest that the lexical-semantic processing of action verbs does not automatically activate the M1. This area seems to be rather involved in post-conceptual processing that follows the retrieval of motor

  5. Homeostatic modulation of stimulation-dependent plasticity in human motor cortex.

    Science.gov (United States)

    Ilić, N V; Milanović, S; Krstić, J; Bajec, D D; Grajić, M; Ilić, T V

    2011-01-01

    Since recently, it is possible, using noninvasive cortical stimulation, such as the protocol of paired associative stimulation (PAS), to induce the plastic changes in the motor cortex, in humans that mimic Hebb's model of learning. Application of TMS conjugated with peripheral electrical stimulation at strictly coherent temporal manner lead to convergence of inputs in the sensory-motor cortex, with the consequent synaptic potentiation or weakening, if applied repetitively. However, when optimal interstimulus interval (ISI) for induction of LTP-like effects is applied as a single pair, Motor evoked potential (MEP) amplitude inhibition is observed, the paradigm known as short-latency afferent inhibition (SLAI). Aiming to resolve this paradox, PAS protocols were applied, with 200 repetitions of TMS pulses paired with median nerve electrical stimulation, at ISI equal to individual latencies of evoked response of somatosensory cortex (N(20)) (PAS(LTP)), and at ISI of N(20) shortened for 5 msec (PAS(LTD)) - protocols that mimic LTP-like changes in the human motor cortex. MEP amplitudes before, during and after interventions were measured as an indicator based on output signals originating from the motor system. Post-intervention MEP amplitudes following the TMS protocols of PAS(LTP) and PAS(LTD) were facilitated and depressed, respectively, contrary to MEP amplitudes during intervention. During PAS(LTP) MEP amplitudes were significantly decreased in case of PAS(LTP), while in the case of PAS(LTD) an upward trend was observed. In conclusions, a possible explanation for the seemingly paradoxical effect of PAS can be found in the mechanism of homeostatic modulation of plasticity. Those findings indicate the existence of complex relationships in the development of plasticity induced by stimulation, depending on the level of the previous motor cortex excitability.

  6. Modulation of excitability in human primary somatosensory and motor cortex by paired associative stimulation targeting the primary somatosensory cortex.

    Science.gov (United States)

    Kriváneková, Lucia; Lu, Ming-Kuei; Bliem, Barbara; Ziemann, Ulf

    2011-10-01

    Input from primary somatosensory cortex (S1) to primary motor cortex (M1) is important for high-level motor performance, motor skill learning and motor recovery after brain lesion. This study tested the effects of manipulating S1 excitability with paired associative transcranial stimulation (S1-PAS) on M1 excitability. Given the important role of S1 in sensorimotor integration, we hypothesized that changes in S1 excitability would be directly paralleled by changes in M1 excitability. We applied two established protocols (S1-PAS(LTP) and S1-PAS(LTD) ) to the left S1 to induce long-term potentiation (LTP)-like or long-term depression (LTD)-like plasticity. S1 excitability was assessed by the early cortical components (N20-P25) of the median nerve somatosensory-evoked potential. M1 excitability was assessed by motor-evoked potential amplitude and short-interval intracortical inhibition. Effects of S1-PAS(LTP) were compared with those of a PAS(LTP) protocol targeting the left M1 (M1-PAS(LTP) ). S1-PAS(LTP) and S1-PAS(LTD) did not result in significant modifications of S1 or M1 excitability at the group level due to substantial interindividual variability. The individual S1-PAS-induced changes in S1 and M1 excitability showed no correlation. Furthermore, the individual changes in S1 and M1 excitability induced by S1-PAS(LTP) did not correlate with changes in M1 excitability induced by M1-PAS(LTP) . This demonstrates that the effects of S1-PAS in S1 are variable across individuals and, within a given individual, unrelated to those induced by S1-PAS or M1-PAS in M1. Potentially, this extends the opportunities of therapeutic PAS applications because M1-PAS 'non-responders' may well respond to S1-PAS.

  7. Rostral Agranular Insular Cortex Lesion with Motor Cortex Stimulation Enhances Pain Modulation Effect on Neuropathic Pain Model

    Directory of Open Access Journals (Sweden)

    Hyun Ho Jung

    2016-01-01

    Full Text Available It is well known that the insular cortex is involved in the processing of painful input. The aim of this study was to evaluate the pain modulation role of the insular cortex during motor cortex stimulation (MCS. After inducing neuropathic pain (NP rat models by the spared nerve injury method, we made a lesion on the rostral agranular insular cortex (RAIC unilaterally and compared behaviorally determined pain threshold and latency in 2 groups: Group A (NP + MCS; n=7 and Group B (NP + RAIC lesion + MCS; n=7. Also, we simultaneously recorded neuronal activity (NP; n=9 in the thalamus of the ventral posterolateral nucleus and RAIC to evaluate electrophysiological changes from MCS. The pain threshold and tolerance latency increased in Group A with “MCS on” and in Group B with or without “MCS on.” Moreover, its increase in Group B with “MCS on” was more than that of Group B without MCS or of Group A, suggesting that MCS and RAIC lesioning are involved in pain modulation. Compared with the “MCS off” condition, the “MCS on” induced significant threshold changes in an electrophysiological study. Our data suggest that the RAIC has its own pain modulation effect, which is influenced by MCS.

  8. Improvement in precision grip force control with self-modulation of primary motor cortex during motor imagery

    Directory of Open Access Journals (Sweden)

    Maria Laura eBlefari

    2015-02-01

    Full Text Available Motor imagery (MI has shown effectiveness in enhancing motor performance. This may be due to the common neural mechanisms underlying MI and motor execution (ME. The main region of the ME network, the primary motor cortex (M1, has been consistently linked to motor performance. However, the activation of M1 during motor imagery is controversial, which may account for inconsistent rehabilitation therapy outcomes using MI. Here, we examined the relationship between contralateral M1 (cM1 activation during MI and changes in sensorimotor performance. To aid cM1 activity modulation during MI, we used real-time fMRI neurofeedback-guided MI based on cM1 hand area blood oxygen level dependent (BOLD signal in healthy subjects, performing kinesthetic MI of pinching. We used multiple regression analysis to examine the correlation between cM1 BOLD signal and changes in motor performance during an isometric pinching task of those subjects who were able to activate cM1 during motor imagery. Activities in premotor and parietal regions were used as covariates. We found that cM1 activity was positively correlated to improvements in accuracy as well as overall performance improvements, whereas other regions in the sensorimotor network were not. The association between cM1 activation during MI with performance changes indicates that subjects with stronger cM1 activation during MI may benefit more from MI training, with implications towards targeted neurotherapy.

  9. TMS investigations into the task-dependent functional interplay between human posterior parietal and motor cortex.

    Science.gov (United States)

    Koch, Giacomo; Rothwell, John C

    2009-09-14

    Transcranial magnetic stimulation (TMS) can be used in two different ways to investigate the contribution of cortical areas involved in grasp/reach movements in humans. It can produce "virtual lesions" that interfere with activity in particular cortical areas at specific times during a task, or it can be used in a twin coil design to test the excitability of cortical projections to M1 at different times during a task. The former method has described how cortical structures such as the ventral premotor cortex (PMv), dorsal premotor cortex (PMd) and the anterior intraparietal sulcus (aIPS) are important for specific aspects of reaching, grasping and lifting objects. In the latter method, a conditioning stimulus (CS) is first used to activate putative pathways to the motor cortex from, for example, posterior parietal cortex (PPC) or PMd, while a second, test stimulus (TS), delivered over the primary motor cortex a few ms later probes any changes in excitability that are produced by the input. Thus changes in the effectiveness of the conditioning pulse give an indication of how the excitability of the connection changes over time and during a specific task. Here we review studies describing the time course of operation of parallel intracortical circuits and cortico-cortical connections between the PMd, PMv, PPC and M1, thus demonstrating that functional interplay between these areas and the primary motor cortices is not fixed, but can change in a highly task-, condition- and time-dependent manner.

  10. Motor cortex excitability and connectivity in chronic stroke: a multimodal model of functional reorganization.

    Science.gov (United States)

    Volz, Lukas J; Sarfeld, Anna-Sophia; Diekhoff, Svenja; Rehme, Anne K; Pool, Eva-Maria; Eickhoff, Simon B; Fink, Gereon R; Grefkes, Christian

    2015-03-01

    Cerebral ischemia triggers a cascade of cellular processes, which induce neuroprotection, inflammation, apoptosis and regeneration. At the neural network level, lesions concomitantly induce cerebral plasticity. Yet, many stroke survivors are left with a permanent motor deficit, and only little is known about the neurobiological factors that determine functional outcome after stroke. Transcranial magnetic stimulation (TMS) and magnetic resonance imaging (MRI) are non-invasive approaches that allow insights into the functional (re-) organization of the cortical motor system. We here combined neuronavigated TMS, MRI and analyses of connectivity to investigate to which degree recovery of hand function depends on corticospinal tract (CST) damage and biomarkers of cerebral plasticity like cortical excitability and motor network effective connectivity. As expected, individual motor performance of 12 stroke patients with persistent motor deficits was found to depend upon the degree of CST damage but also motor cortex excitability and interhemispheric connectivity. In addition, the data revealed a strong correlation between reduced ipsilesional motor cortex excitability and reduced interhemispheric inhibition in severely impaired patients. Interindividual differences in ipsilesional motor cortex excitability were stronger related to the motor deficit than abnormal interhemispheric connectivity or CST damage. Multivariate linear regression analysis combining the three factors accounted for more than 80 % of the variance in functional impairment. The inter-relation of cortical excitability and reduced interhemispheric inhibition provides direct multi-modal evidence for the disinhibition theory of the contralesional hemisphere following stroke. Finally, our data reveal a key mechanism (i.e., the excitability-related reduction in interhemispheric inhibition) accounting for the rehabilitative potential of novel therapeutic approaches which aim at modulating cortical

  11. Seeing fearful body language rapidly freezes the observer's motor cortex

    NARCIS (Netherlands)

    Borgomaneri, Sara; Vitale, Francesca; Gazzola, V.; Avenanti, Alessio

    2015-01-01

    Fearful body language is a salient signal alerting the observer to the presence of a potential threat in the surrounding environment. Although detecting potential threats may trigger an immediate reduction of motor output in animals (i.e., freezing behavior), it is unclear at what point in time simi

  12. Poor Tolerance of Motor Cortex rTMS in Chronic Migraine

    Science.gov (United States)

    Teo, Wei-Peng; Kannan, Aravinda; Loh, Pei-Kee; Chew, Effie; Sharma, Vijay Kumar

    2014-01-01

    Background: Two small studies had evaluated the efficacy of rTMS in migraine. One tested high frequency rTMS over the dorsolateral prefrontal cortex while the other evaluated 1 Hz rTMS over the vertex. Aim: To test the feasibility of 10 Hz rTMS of motor cortex as an adjunctive therapy in patients with chronic migraine Materials and Methods: We randomized (2:1 ratio) chronic migraine patients on medical preventive treatment to receive either rTMS or sham therapy for 10 sessions. rTMS (80% resting motor threshold, 10Hz, 20 trains, 5 secs/train, inter-train interval 1 min, total 1000 stimuli/session) was applied over the right motor cortex. Result: Nine patients were randomized. Six received rTMS and three had sham therapy. Three patients in the rTMS arm withdrew from the study due to increased headache frequency and discomfort from the treatment. The remaining six cases (3 rTMS, 3 sham) completed the study. The study was prematurely stopped due to the significant worsening of headache from rTMS. No significant differences in outcome measures were found between real and sham rTMS. Conclusion: Although the study was terminated prematurely, the high dropout rate (50%) due to worsening headaches suggested that rTMS over the motor cortex is poorly tolerated in chronic migraine. PMID:25386478

  13. Multitarget Multiscale Simulation for Pharmacological Treatment of Dystonia in Motor Cortex

    Science.gov (United States)

    Neymotin, Samuel A.; Dura-Bernal, Salvador; Lakatos, Peter; Sanger, Terence D.; Lytton, William W.

    2016-01-01

    A large number of physiomic pathologies can produce hyperexcitability in cortex. Depending on severity, cortical hyperexcitability may manifest clinically as a hyperkinetic movement disorder or as epilpesy. We focus here on dystonia, a movement disorder that produces involuntary muscle contractions and involves pathology in multiple brain areas including basal ganglia, thalamus, cerebellum, and sensory and motor cortices. Most research in dystonia has focused on basal ganglia, while much pharmacological treatment is provided directly at muscles to prevent contraction. Motor cortex is another potential target for therapy that exhibits pathological dynamics in dystonia, including heightened activity and altered beta oscillations. We developed a multiscale model of primary motor cortex, ranging from molecular, up to cellular, and network levels, containing 1715 compartmental model neurons with multiple ion channels and intracellular molecular dynamics. We wired the model based on electrophysiological data obtained from mouse motor cortex circuit mapping experiments. We used the model to reproduce patterns of heightened activity seen in dystonia by applying independent random variations in parameters to identify pathological parameter sets. These models demonstrated degeneracy, meaning that there were many ways of obtaining the pathological syndrome. There was no single parameter alteration which would consistently distinguish pathological from physiological dynamics. At higher dimensions in parameter space, we were able to use support vector machines to distinguish the two patterns in different regions of space and thereby trace multitarget routes from dystonic to physiological dynamics. These results suggest the use of in silico models for discovery of multitarget drug cocktails. PMID:27378922

  14. Multitarget Multiscale Simulation for Pharmacological Treatment of Dystonia in Motor Cortex.

    Science.gov (United States)

    Neymotin, Samuel A; Dura-Bernal, Salvador; Lakatos, Peter; Sanger, Terence D; Lytton, William W

    2016-01-01

    A large number of physiomic pathologies can produce hyperexcitability in cortex. Depending on severity, cortical hyperexcitability may manifest clinically as a hyperkinetic movement disorder or as epilpesy. We focus here on dystonia, a movement disorder that produces involuntary muscle contractions and involves pathology in multiple brain areas including basal ganglia, thalamus, cerebellum, and sensory and motor cortices. Most research in dystonia has focused on basal ganglia, while much pharmacological treatment is provided directly at muscles to prevent contraction. Motor cortex is another potential target for therapy that exhibits pathological dynamics in dystonia, including heightened activity and altered beta oscillations. We developed a multiscale model of primary motor cortex, ranging from molecular, up to cellular, and network levels, containing 1715 compartmental model neurons with multiple ion channels and intracellular molecular dynamics. We wired the model based on electrophysiological data obtained from mouse motor cortex circuit mapping experiments. We used the model to reproduce patterns of heightened activity seen in dystonia by applying independent random variations in parameters to identify pathological parameter sets. These models demonstrated degeneracy, meaning that there were many ways of obtaining the pathological syndrome. There was no single parameter alteration which would consistently distinguish pathological from physiological dynamics. At higher dimensions in parameter space, we were able to use support vector machines to distinguish the two patterns in different regions of space and thereby trace multitarget routes from dystonic to physiological dynamics. These results suggest the use of in silico models for discovery of multitarget drug cocktails.

  15. How electrode montage affects transcranial direct current stimulation of the human motor cortex.

    Science.gov (United States)

    Salvador, Ricardo; Wenger, Cornelia; Nitsche, Michael A; Miranda, Pedro C

    2015-01-01

    Several different electrode configurations were originally proposed to induce excitability changes in the hand area of the motor cortex in transcranial direct current stimulation (tDCS). However only one was found to efficiently affect cortical excitability: anode/cathode over the primary motor cortex and return electrode placed over the contralateral orbit (M-CF configuration). In this work we used the finite element method to calculate the electric field (E-field) induced in a realistic human head model in all the proposed electrode configurations. In order to analyze the results, average values of the E-field's magnitude and polar/azimuthal angles were calculated in several cortical motor and premotor areas which may have an effect on the output of the primary motor cortex. The average E-field's magnitude at the hand-knob (HK) was similar between the M-CF configuration (0.16 V/m) and a few other tested configurations, the same happening for the average polar angle (129°). However this configuration achieved the highest mean E-field values over premotor (PM) areas (0.21 V/m). These results show that the polar angle and the average magnitude of the E-field evaluated at the HK and at the PM cortex might be important parameters in predicting the success of a specific electrode montage in tDCS.

  16. Representation of the Speech Effectors in the Human Motor Cortex: Somatotopy or Overlap?

    Science.gov (United States)

    Takai, Osamu; Brown, Steven; Liotti, Mario

    2010-01-01

    Somatotopy within the orofacial region of the human motor cortex has been a central concept in interpreting the results of neuroimaging and transcranial magnetic stimulation studies of normal and disordered speech. Yet, somatotopy has been challenged by studies showing overlap among the effectors within the homunculus. In order to address this…

  17. The involvement of the left motor cortex in learning of a novel action word lexicon

    NARCIS (Netherlands)

    Liuzzi, Gianpiero; Freundlieb, Nils; Ridder, Volker; Hoppe, Julia; Heise, Kirstin; Zimerman, Maximo; Dobel, Christian; Enriquez-Geppert, Stefanie; Gerloff, Christian; Zwitserlood, Pienie; Hummel, Friedhelm C

    2010-01-01

    Current theoretical positions assume that action-related word meanings are established by functional connections between perisylvian language areas and the motor cortex (MC) according to Hebb's associative learning principle. To test this assumption, we probed the functional relevance of the left MC

  18. Differentiating functions of the lateral and medial prefrontal cortex in motor response inhibition.

    Science.gov (United States)

    H Rodrigo, Achala; Domenico, Stefano I Di; Ayaz, Hasan; Gulrajani, Sean; Lam, Jaeger; Ruocco, Anthony C

    2014-01-15

    The right inferior frontal gyrus is generally considered a critical region for motor response inhibition. Recent studies, however, suggest that the role of this cortical area in response inhibition may be overstated and that the contributions of other aspects of the prefrontal cortex are often overlooked. The current study used optical imaging to identify regions of the prefrontal cortex beyond the right inferior frontal gyrus which may serve to support motor response inhibition. Forty-three right-handed healthy adults completed a manual Go/No-Go task while evoked oxygenation of the prefrontal cortex was measured using 16-channel functional near-infrared spectroscopy. During motor response inhibition, the right inferior frontal gyrus, and to a lesser extent the homologous contralateral region, showed increased activation relative to a baseline task. Conversely, the medial prefrontal cortex was significantly deactivated, and the extent of reduced activity in this region was associated with fewer errors on the response inhibition task. These findings suggest a more substantial role of the left inferior frontal gyrus in response inhibition and possibly a distinct function of the middle frontal gyrus subserving error detection on manual motor control tasks.

  19. Reduced functional connectivity within the primary motor cortex of patients with brachial plexus injury

    NARCIS (Netherlands)

    Fraiman, D.; Miranda, M.F.; Erthal, F.; Buur, P.F.; Elschot, M.; Souza, L.; Rombouts, S.A.; Schimmelpenninck, C.A.; Norris, D.G.; Malessy, M.J.; Galves, A.; Vargas, C.D.

    2016-01-01

    This study aims at the effects of traumatic brachial plexus lesion with root avulsions (BPA) upon the organization of the primary motor cortex (M1). Nine right-handed patients with a right BPA in whom an intercostal to musculocutaneous (ICN-MC) nerve transfer was performed had post-operative resting

  20. Low Intensity Focused tDCS Over the Motor Cortex Shows Inefficacy to Improve Motor Imagery Performance

    Directory of Open Access Journals (Sweden)

    Irma N. Angulo-Sherman

    2017-07-01

    Full Text Available Transcranial direct current stimulation (tDCS is a brain stimulation technique that can enhance motor activity by stimulating the motor path. Thus, tDCS has the potential of improving the performance of brain-computer interfaces during motor neurorehabilitation. tDCS effects depend on several aspects, including the current density, which usually varies between 0.02 and 0.08 mA/cm2, and the location of the stimulation electrodes. Hence, testing tDCS montages at several current levels would allow the selection of current parameters for improving stimulation outcomes and the comparison of montages. In a previous study, we found that cortico-cerebellar tDCS shows potential of enhancing right-hand motor imagery. In this paper, we aim to evaluate the effects of the focal stimulation of the motor cortex over motor imagery. In particular, the effect of supplying tDCS with a 4 × 1 ring montage, which consists in placing an anode on the motor cortex and four cathodes around it, over motor imagery was assessed with different current densities. Electroencephalographic (EEG classification into rest or right-hand/feet motor imagery was evaluated on five healthy subjects for two stimulation schemes: applying tDCS for 10 min on the (1 right-hand or (2 feet motor cortex before EEG recording. Accuracy differences related to the tDCS intensity, as well as μ and β band power changes, were tested for each subject and tDCS modality. In addition, a simulation of the electric field induced by the montage was used to describe its effect on the brain. Results show no improvement trends on classification for the evaluated currents, which is in accordance with the observation of variable EEG band power results despite the focused stimulation. The lack of effects is probably related to the underestimation of the current intensity required to apply a particular current density for small electrodes and the relatively short inter-electrode distance. Hence, higher current

  1. Somatotopic mapping of the human primary sensorimotor cortex during motor imagery and motor execution by functional magnetic resonance imaging.

    Science.gov (United States)

    Stippich, Christoph; Ochmann, Henrik; Sartor, Klaus

    2002-10-04

    The human primary sensorimotor cortex was investigated for somatotopic organization during motor imagery (IM) which was compared to motor execution (EM). Block designed BOLD (blood oxygen level dependent)-functional magnetic resonance imaging at 1.5 Tesla was applied in 14 right handed volunteers during imagined and executed tongue, finger and toe movements. BOLD-clusters were assessed for anatomically correct sensorimotor localization. Euklidian coordinates, relative signal change and correlation to the applied reference function were determined. Statistical means were calculated. IM recruited somatotopically organized primary sensorimotor representations of the precentral gyrus that reflected the homunculus and overlapped in part with EM representations. Mean BOLD-signals ranged from 1.93 to 3.18% for EM, and from 0.73 to 1.47% for IM. The results support the hypothesis that the primary sensorimotor cortex is active during IM and that IM and EM share common functional circuits.

  2. Proton magnetic resonance spectroscopy of the motor cortex in cervical myelopathy.

    Science.gov (United States)

    Kowalczyk, Izabela; Duggal, Neil; Bartha, Robert

    2012-02-01

    Alterations in motor function in cervical myelopathy secondary to degenerative disease may be due to local effects of spinal compression or distal effects related to cortical reorganization. This prospective study characterizes differences in metabolite levels in the motor cortex, specifically N-acetylaspartate, creatine, choline, myo-inositol and glutamate plus glutamine, due to alterations in cortical function in patients with reversible spinal cord compression compared with healthy controls. We hypothesized that N-acetylaspartate/creatine levels would be decreased in the motor cortex of patients with cervical myelopathy due to reduced neuronal integrity/function and myo-inositol/creatine levels would be increased due to reactive gliosis. Twenty-four patients with cervical myelopathy and 11 healthy controls underwent proton-magnetic resonance spectroscopy on a 3.0 Tesla Siemens Magnetom Tim Trio MRI. Areas of activation from functional magnetic resonance imaging scans of a finger-tapping paradigm were used to localize a voxel on the side of greater motor deficit in the myelopathy group (n = 10 on right side and n = 14 on left side of the brain) and on each side of the motor cortex in controls. Neurological function was measured with the Neck Disability Index, modified Japanese Orthopaedic Association and American Spinal Injury Association questionnaires. Metabolite levels were measured relative to total creatine within the voxel of interest. No metabolite differences were detected between the right side and left side of the motor cortex in controls. The myelopathy group had significantly decreased neurological function compared with the control group (Neck Disability Index: P motor cortex of the myelopathy group (1.21 ± 0.07) compared with the right (1.37 ± 0.03; P = 0.01) and left (1.38 ± 0.03; P = 0.007) motor cortex in controls suggesting neuronal damage or dysfunction distal to the lesion in the spine. No difference was

  3. Occlusion of LTP-like plasticity in human primary motor cortex by action observation.

    Directory of Open Access Journals (Sweden)

    Jean-François Lepage

    Full Text Available Passive observation of motor actions induces cortical activity in the primary motor cortex (M1 of the onlooker, which could potentially contribute to motor learning. While recent studies report modulation of motor performance following action observation, the neurophysiological mechanism supporting these behavioral changes remains to be specifically defined. Here, we assessed whether the observation of a repetitive thumb movement--similarly to active motor practice--would inhibit subsequent long-term potentiation-like (LTP plasticity induced by paired-associative stimulation (PAS. Before undergoing PAS, participants were asked to either 1 perform abductions of the right thumb as fast as possible; 2 passively observe someone else perform thumb abductions; or 3 passively observe a moving dot mimicking thumb movements. Motor evoked potentials (MEP were used to assess cortical excitability before and after motor practice (or observation and at two time points following PAS. Results show that, similarly to participants in the motor practice group, individuals observing repeated motor actions showed marked inhibition of PAS-induced LTP, while the "moving dot" group displayed the expected increase in MEP amplitude, despite differences in baseline excitability. Interestingly, LTP occlusion in the action-observation group was present even if no increase in cortical excitability or movement speed was observed following observation. These results suggest that mere observation of repeated hand actions is sufficient to induce LTP, despite the absence of motor learning.

  4. Linear summation of outputs in a balanced network model of motor cortex.

    Science.gov (United States)

    Capaday, Charles; van Vreeswijk, Carl

    2015-01-01

    Given the non-linearities of the neural circuitry's elements, we would expect cortical circuits to respond non-linearly when activated. Surprisingly, when two points in the motor cortex are activated simultaneously, the EMG responses are the linear sum of the responses evoked by each of the points activated separately. Additionally, the corticospinal transfer function is close to linear, implying that the synaptic interactions in motor cortex must be effectively linear. To account for this, here we develop a model of motor cortex composed of multiple interconnected points, each comprised of reciprocally connected excitatory and inhibitory neurons. We show how non-linearities in neuronal transfer functions are eschewed by strong synaptic interactions within each point. Consequently, the simultaneous activation of multiple points results in a linear summation of their respective outputs. We also consider the effects of reduction of inhibition at a cortical point when one or more surrounding points are active. The network response in this condition is linear over an approximately two- to three-fold decrease of inhibitory feedback strength. This result supports the idea that focal disinhibition allows linear coupling of motor cortical points to generate movement related muscle activation patterns; albeit with a limitation on gain control. The model also explains why neural activity does not spread as far out as the axonal connectivity allows, whilst also explaining why distant cortical points can be, nonetheless, functionally coupled by focal disinhibition. Finally, we discuss the advantages that linear interactions at the cortical level afford to motor command synthesis.

  5. Motor cortex representation of the upper-limb in individuals born without a hand.

    Directory of Open Access Journals (Sweden)

    Karen T Reilly

    Full Text Available The body schema is an action-related representation of the body that arises from activity in a network of multiple brain areas. While it was initially thought that the body schema developed with experience, the existence of phantom limbs in individuals born without a limb (amelics led to the suggestion that it was innate. The problem with this idea, however, is that the vast majority of amelics do not report the presence of a phantom limb. Transcranial magnetic stimulation (TMS applied over the primary motor cortex (M1 of traumatic amputees can evoke movement sensations in the phantom, suggesting that traumatic amputation does not delete movement representations of the missing hand. Given this, we asked whether the absence of a phantom limb in the majority of amelics means that the motor cortex does not contain a cortical representation of the missing limb, or whether it is present but has been deactivated by the lack of sensorimotor experience. In four upper-limb amelic subjects we directly stimulated the arm/hand region of M1 to see 1 whether we could evoke phantom sensations, and 2 whether muscle representations in the two cortices were organised asymmetrically. TMS applied over the motor cortex contralateral to the missing limb evoked contractions in stump muscles but did not evoke phantom movement sensations. The location and extent of muscle maps varied between hemispheres but did not reveal any systematic asymmetries. In contrast, forearm muscle thresholds were always higher for the missing limb side. We suggest that phantom movement sensations reported by some upper limb amelics are mostly driven by vision and not by the persistence of motor commands to the missing limb within the sensorimotor cortex. We propose that prewired movement representations of a limb need the experience of movement to be expressed within the primary motor cortex.

  6. Potential mechanisms supporting the value of motor cortex stimulation to treat chronic pain syndromes

    Directory of Open Access Journals (Sweden)

    Marcos Fabio DosSantos

    2016-02-01

    Full Text Available Throughout the first years of the twenty-first century, neurotechnologies such as motor cortex stimulation (MCS, transcranial magnetic stimulation (TMS and transcranial direct current stimulation (tDCS have attracted scientific attention and been considered as potential tools to centrally modulate chronic pain, especially for those conditions more difficult to manage and refractory to all types of available pharmacological therapies. Interestingly, although the role of the motor cortex in pain has not been fully clarified, it is one of the cortical areas most commonly targeted by invasive and non-invasive neuromodulation technologies. Recent studies have provided significant advances concerning the establishment of the clinical effectiveness of primary motor cortex stimulation to treat different chronic pain syndromes. Concurrently, the neuromechanisms related to each method of primary motor cortex (M1 modulation have been unveiled. In this respect, the most consistent scientific evidence originates from MCS studies, which indicate the activation of top-down controls driven by M1 stimulation. This concept has also been applied to explain M1-TMS mechanisms. Nevertheless, activation of remote areas in the brain, including cortical and subcortical structures, has been reported with both invasive and non-invasive methods and the participation of major neurotransmitters (e.g. glutamate, GABA and serotonin as well as the release of endogenous opioids has been demonstrated. In this critical review, the putative mechanisms underlying the use of motor cortex stimulation to provide relief from chronic migraine and other types of chronic pain are discussed. Emphasis is placed on the most recent scientific evidence obtained from chronic pain research studies involving MCS and non-invasive neuromodulation methods (e.g. tDCS and TMS, which are analyzed comparatively.

  7. [Quality of neuronal signal registered in the monkey motor cortex with chronically implanted multiple microwires].

    Science.gov (United States)

    Bondar', I V; Vasil'eva, L N; Badakva, A M; Miller, N V; Zobova, L N; Roshchin, V Iu

    2014-01-01

    Disconnection of central and peripheral parts of motor system leads to severe forms of disability. However, current research of brain-computer interfaces will solve the problem of rehabilitation of patients with motor disorders in future. Chronic recordings of single-unit activity in specialized areas of cerebral cortex could provide appropriate control signal for effectors with multiple degrees of freedom. In present article we evaluated the quality of chronic single-unit recordings in the primary motor cortex of awake behaving monkeys obtained with bundles of multiple microwires. Action potentials of proper quality were recorded from single units during three months. In some cases up to 7 single units could be extracted on a channel. Recording quality stabilized after 40 days since electrodes were implanted. Ultimately, functionality of multiple electrodes bundle makes it highly usable and reliable instrument for obtaining of control neurophysiologic signal from populations of neurons for brain-computer interfaces.

  8. Influence of position and stimulation parameters on intracortical inhibition and facilitation in human tongue motor cortex

    DEFF Research Database (Denmark)

    Kothari, Mohit; Svensson, Peter; Nielsen, Jørgen Feldbæk

    Paired-pulse transcranial magnetic stimulation (ppTMS) can be used to assess short-interval intracortical inhibitory (SICI) and facilitatory (ICF) networks. The aim of the study was to examine the influence of body positions (recline and supine), inter-stimulus intervals (ISI) between the test...... stimulus (TS) and conditioning stimulus (CS) and intensities of the TS and CS on the degree of SICI and ICF. In study 1 and 2, fourteen and seventeen healthy volunteers participated respectively. ppTMS was applied over the “hot-spot” of the tongue motor cortex and motor evoked potentials (MEPs) were.......042) in study 1. In study 2, there was a significant effect of ISI (PICF in the tongue motor cortex....

  9. Selective Suppression of Local Circuits during Movement Preparation in the Mouse Motor Cortex

    Directory of Open Access Journals (Sweden)

    Masashi Hasegawa

    2017-03-01

    Full Text Available Prepared movements are more efficient than those that are not prepared for. Although changes in cortical activity have been observed prior to a forthcoming action, the circuits involved in motor preparation remain unclear. Here, we use in vivo two-photon calcium imaging to uncover changes in the motor cortex during variable waiting periods prior to a forepaw reaching task in mice. Consistent with previous reports, we observed a subset of neurons with increased activity during the waiting period; however, these neurons did not account for the degree of preparation as defined by reaction time (RT. Instead, the suppression of activity of distinct neurons in the same cortical area better accounts for RT. This suppression of neural activity resulted in a distinct and reproducible pattern when mice were well prepared. Thus, the selective suppression of network activity in the motor cortex may be a key feature of prepared movements.

  10. Constructing Visual Perception of Body Movement with the Motor Cortex.

    Science.gov (United States)

    Orgs, Guido; Dovern, Anna; Hagura, Nobuhiro; Haggard, Patrick; Fink, Gereon R; Weiss, Peter H

    2016-01-01

    The human brain readily perceives fluent movement from static input. Using functional magnetic resonance imaging, we investigated brain mechanisms that mediate fluent apparent biological motion (ABM) perception from sequences of body postures. We presented body and nonbody stimuli varying in objective sequence duration and fluency of apparent movement. Three body postures were ordered to produce a fluent (ABC) or a nonfluent (ACB) apparent movement. This enabled us to identify brain areas involved in the perceptual reconstruction of body movement from identical lower-level static input. Participants judged the duration of a rectangle containing body/nonbody sequences, as an implicit measure of movement fluency. For body stimuli, fluent apparent motion sequences produced subjectively longer durations than nonfluent sequences of the same objective duration. This difference was reduced for nonbody stimuli. This body-specific bias in duration perception was associated with increased blood oxygen level-dependent responses in the primary (M1) and supplementary motor areas. Moreover, fluent ABM was associated with increased functional connectivity between M1/SMA and right fusiform body area. We show that perceptual reconstruction of fluent movement from static body postures does not merely enlist areas traditionally associated with visual body processing, but involves cooperative recruitment of motor areas, consistent with a "motor way of seeing".

  11. Human Motor Cortex Functional Changes in Acute Stroke: Gender Effects

    Directory of Open Access Journals (Sweden)

    Vincenzo eDi Lazzaro

    2016-01-01

    Full Text Available The acute phase of stroke is accompanied by functional changes in the activity and interplay of both hemispheres. In healthy subjects, gender is known to impact the functional brain organization.We investigated whether gender influences also acute stroke functional changes. In thirty-five ischemic stroke patients, we evaluated the excitability of the affected (AH and unaffected hemisphere (UH by measuring resting and active motor threshold and motor-evoked potential amplitude under baseline conditions and after intermittent theta burst stimulation (iTBS of AH. We also computed an index of the excitability balance between the hemispheres, laterality indexes (LI, to evidence hemispheric asymmetry. Active motor threshold differed significantly between AH and UH only in the male group (p=0.004, not in females (p>0.200, and both LIAMT and LIRMT were significantly higher in males than in females (respectively p=0.033 and p=0.042. LTP-like activity induced by iTBS in AH was more frequent in females. Gender influences the functional excitability changes that take place after human stroke and the level of LTP that can be induced by repetitive stimulation. This knowledge is of high value in the attempt of individualizing to different genders any non-invasive stimulation strategy designed to foster stroke recovery.

  12. Influence of Motor Cortex Stimulation During Motor Training on Neuroplasticity as a Potential Therapeutic Intervention.

    Science.gov (United States)

    Massie, Crystal L; White, Caylen; Pruit, Katie; Freel, Aubrey; Staley, Kaylin; Backes, Morgan

    2017-02-06

    Rehabilitation options to promote neuroplasticity may be enhanced when patients are engaged in motor practice during repetitive transcranial magnetic stimulation (rTMS). Twelve participants completed 3 separate sessions: motor practice, motor practice with rTMS, and rTMS only: motor practice consisted of 30 isometric contractions and subthreshold rTMS was 30, 3-s trains at 10 Hz. Assessments included the Box and Block Test (BBT), force steadiness (10% of the maximum voluntary contraction), and TMS (cortical excitability, intracortical inhibition, and intracortical facilitation). Participants significantly increased BBT scores following the combined condition. Force steadiness improved after all 3 conditions (p motor practice plus rTMS condition. All interventions influenced motor control, yet are likely modulated differently when combining motor practice plus rTMS. These results help guide the clinical utility of rTMS as an intervention to influence motor control.

  13. Robust tactile sensory responses in finger area of primate motor cortex relevant to prosthetic control

    Science.gov (United States)

    Schroeder, Karen E.; Irwin, Zachary T.; Bullard, Autumn J.; Thompson, David E.; Bentley, J. Nicole; Stacey, William C.; Patil, Parag G.; Chestek, Cynthia A.

    2017-08-01

    Objective. Challenges in improving the performance of dexterous upper-limb brain-machine interfaces (BMIs) have prompted renewed interest in quantifying the amount and type of sensory information naturally encoded in the primary motor cortex (M1). Previous single unit studies in monkeys showed M1 is responsive to tactile stimulation, as well as passive and active movement of the limbs. However, recent work in this area has focused primarily on proprioception. Here we examined instead how tactile somatosensation of the hand and fingers is represented in M1. Approach. We recorded multi- and single units and thresholded neural activity from macaque M1 while gently brushing individual finger pads at 2 Hz. We also recorded broadband neural activity from electrocorticogram (ECoG) grids placed on human motor cortex, while applying the same tactile stimulus. Main results. Units displaying significant differences in firing rates between individual fingers (p  motor finger responses, the percentage of electrodes with significant tactile responses was 74.9%  ±  24.7%. No somatotopic organization of finger preference was obvious across cortex, but many units exhibited cosine-like tuning across multiple digits. Sufficient sensory information was present in M1 to correctly decode stimulus position from multiunit activity above chance levels in all monkeys, and also from ECoG gamma power in two human subjects. Significance. These results provide some explanation for difficulties experienced by motor decoders in clinical trials of cortically controlled prosthetic hands, as well as the general problem of disentangling motor and sensory signals in primate motor cortex during dextrous tasks. Additionally, examination of unit tuning during tactile and proprioceptive inputs indicates cells are often tuned differently in different contexts, reinforcing the need for continued refinement of BMI training and decoding approaches to closed-loop BMI systems for dexterous grasping.

  14. Speed of processing in the primary motor cortex: a continuous theta burst stimulation study.

    Science.gov (United States)

    Lakhani, Bimal; Bolton, David A E; Miyasike-Dasilva, Veronica; Vette, Albert H; McIlroy, William E

    2014-03-15

    'Temporally urgent' reactions are extremely rapid, spatially precise movements that are evoked following discrete stimuli. The involvement of primary motor cortex (M1) and its relationship to stimulus intensity in such reactions is not well understood. Continuous theta burst stimulation (cTBS) suppresses focal regions of the cortex and can assess the involvement of motor cortex in speed of processing. The primary objective of this study was to explore the involvement of M1 in speed of processing with respect to stimulus intensity. Thirteen healthy young adults participated in this experiment. Behavioral testing consisted of a simple button press using the index finger following median nerve stimulation of the opposite limb, at either high or low stimulus intensity. Reaction time was measured by the onset of electromyographic activity from the first dorsal interosseous (FDI) muscle of each limb. Participants completed a 30 min bout of behavioral testing prior to, and 15 min following, the delivery of cTBS to the motor cortical representation of the right FDI. The effect of cTBS on motor cortex was measured by recording the average of 30 motor evoked potentials (MEPs) just prior to, and 5 min following, cTBS. Paired t-tests revealed that, of thirteen participants, five demonstrated a significant attenuation, three demonstrated a significant facilitation and five demonstrated no significant change in MEP amplitude following cTBS. Of the group that demonstrated attenuated MEPs, there was a biologically significant interaction between stimulus intensity and effect of cTBS on reaction time and amplitude of muscle activation. This study demonstrates the variability of potential outcomes associated with the use of cTBS and further study on the mechanisms that underscore the methodology is required. Importantly, changes in motor cortical excitability may be an important determinant of speed of processing following high intensity stimulation.

  15. Neurophysiologic correlates of fMRI in human motor cortex.

    Science.gov (United States)

    Hermes, Dora; Miller, Kai J; Vansteensel, Mariska J; Aarnoutse, Erik J; Leijten, Frans S S; Ramsey, Nick F

    2012-07-01

    The neurophysiological underpinnings of functional magnetic resonance imaging (fMRI) are not well understood. To understand the relationship between the fMRI blood oxygen level dependent (BOLD) signal and neurophysiology across large areas of cortex, we compared task related BOLD change during simple finger movement to brain surface electric potentials measured on a similar spatial scale using electrocorticography (ECoG). We found that spectral power increases in high frequencies (65-95 Hz), which have been related to local neuronal activity, colocalized with spatially focal BOLD peaks on primary sensorimotor areas. Independent of high frequencies, decreases in low frequency rhythms (neurophysiological mechanisms, one being spatially focal neuronal processing and the other spatially distributed low frequency rhythms. Copyright © 2011 Wiley-Liss, Inc.

  16. Task-dependent interaction between parietal and contralateral primary motor cortex during explicit versus implicit motor imagery.

    Directory of Open Access Journals (Sweden)

    Florent Lebon

    Full Text Available Both mental rotation (MR and motor imagery (MI involve an internalization of movement within motor and parietal cortex. Transcranial magnetic stimulation (TMS techniques allow for a task-dependent investigation of the interhemispheric interaction between these areas. We used image-guided dual-coil TMS to investigate interactions between right inferior parietal lobe (rIPL and left primary motor cortex (M1 in 11 healthy participants. They performed MI (right index-thumb pinching in time with a 1 Hz metronome or hand MR tasks, while motor evoked potentials (MEPs were recorded from right first dorsal interosseous. At rest, rIPL conditioning 6 ms prior to M1 stimulation facilitated MEPs in all participants, whereas this facilitation was abolished during MR. While rIPL conditioning 12 ms prior to M1 stimulation had no effect on MEPs at rest, it suppressed corticomotor excitability during MI. These results support the idea that rIPL forms part of a distinct inhibitory network that may prevent unwanted movement during imagery tasks.

  17. Transcranial direct current stimulation reverses neurophysiological and behavioural effects of focal inhibition of human pharyngeal motor cortex on swallowing.

    Science.gov (United States)

    Vasant, Dipesh H; Mistry, Satish; Michou, Emilia; Jefferson, Samantha; Rothwell, John C; Hamdy, Shaheen

    2014-02-15

    The human cortical swallowing system exhibits bilateral but functionally asymmetric representation in health and disease as evidenced by both focal cortical inhibition (pre-conditioning with 1 Hz repetitive transcranial magnetic stimulation; rTMS) and unilateral stroke, where disruption of the stronger (dominant) pharyngeal projection alters swallowing neurophysiology and behaviour. Moreover, excitatory neurostimulation protocols capable of reversing the disruptive effects of focal cortical inhibition have demonstrated therapeutic promise in post-stroke dysphagia when applied contralaterally. In healthy participants (n = 15, 8 males, mean age (±SEM) 35 ± 9 years), optimal parameters of transcranial direct current stimulation (tDCS) (anodal, 1.5 mA, 10 min) were applied contralaterally after 1 Hz rTMS pre-conditioning to the strongest pharyngeal projection. Swallowing neurophysiology was assessed in both hemispheres by intraluminal recordings of pharyngeal motor-evoked responses (PMEPs) to single-pulse TMS as a measure of cortical excitability. Swallowing behaviour was examined using a pressure-based reaction time protocol. Measurements were made before and for up to 60 min post intervention. Subjects were randomised to active or sham tDCS after 1 Hz rTMS on separate days and data were compared using repeated measures ANOVA. Active tDCS increased PMEPs bilaterally (F1,14 = 7.4, P = 0.017) reversing the inhibitory effects of 1 Hz rTMS in the pre-conditioned hemisphere (F1,14 = 10.1, P = 0.007). Active tDCS also enhanced swallowing behaviour, increasing the number of correctly timed challenge swallows compared to sham (F1,14 = 6.3, P = 0.025). Thus, tDCS to the contralateral pharyngeal motor cortex reverses the neurophysiological and behavioural effects of focal cortical inhibition on swallowing in healthy individuals and has therapeutic potential for dysphagia rehabilitation.

  18. Trunk robot rehabilitation training with active stepping reorganizes and enriches trunk motor cortex representations in spinal transected rats.

    Science.gov (United States)

    Oza, Chintan S; Giszter, Simon F

    2015-05-01

    Trunk motor control is crucial for postural stability and propulsion after low thoracic spinal cord injury (SCI) in animals and humans. Robotic rehabilitation aimed at trunk shows promise in SCI animal models and patients. However, little is known about the effect of SCI and robot rehabilitation of trunk on cortical motor representations. We previously showed reorganization of trunk motor cortex after adult SCI. Non-stepping training also exacerbated some SCI-driven plastic changes. Here we examine effects of robot rehabilitation that promotes recovery of hindlimb weight support functions on trunk motor cortex representations. Adult rats spinal transected as neonates (NTX rats) at the T9/10 level significantly improve function with our robot rehabilitation paradigm, whereas treadmill-only trained do not. We used intracortical microstimulation to map motor cortex in two NTX groups: (1) treadmill trained (control group); and (2) robot-assisted treadmill trained (improved function group). We found significant robot rehabilitation-driven changes in motor cortex: (1) caudal trunk motor areas expanded; (2) trunk coactivation at cortex sites increased; (3) richness of trunk cortex motor representations, as examined by cumulative entropy and mutual information for different trunk representations, increased; (4) trunk motor representations in the cortex moved toward more normal topography; and (5) trunk and forelimb motor representations that SCI-driven plasticity and compensations had caused to overlap were segregated. We conclude that effective robot rehabilitation training induces significant reorganization of trunk motor cortex and partially reverses some plastic changes that may be adaptive in non-stepping paraplegia after SCI.

  19. Trunk Robot Rehabilitation Training with Active Stepping Reorganizes and Enriches Trunk Motor Cortex Representations in Spinal Transected Rats

    Science.gov (United States)

    Oza, Chintan S.

    2015-01-01

    Trunk motor control is crucial for postural stability and propulsion after low thoracic spinal cord injury (SCI) in animals and humans. Robotic rehabilitation aimed at trunk shows promise in SCI animal models and patients. However, little is known about the effect of SCI and robot rehabilitation of trunk on cortical motor representations. We previously showed reorganization of trunk motor cortex after adult SCI. Non-stepping training also exacerbated some SCI-driven plastic changes. Here we examine effects of robot rehabilitation that promotes recovery of hindlimb weight support functions on trunk motor cortex representations. Adult rats spinal transected as neonates (NTX rats) at the T9/10 level significantly improve function with our robot rehabilitation paradigm, whereas treadmill-only trained do not. We used intracortical microstimulation to map motor cortex in two NTX groups: (1) treadmill trained (control group); and (2) robot-assisted treadmill trained (improved function group). We found significant robot rehabilitation-driven changes in motor cortex: (1) caudal trunk motor areas expanded; (2) trunk coactivation at cortex sites increased; (3) richness of trunk cortex motor representations, as examined by cumulative entropy and mutual information for different trunk representations, increased; (4) trunk motor representations in the cortex moved toward more normal topography; and (5) trunk and forelimb motor representations that SCI-driven plasticity and compensations had caused to overlap were segregated. We conclude that effective robot rehabilitation training induces significant reorganization of trunk motor cortex and partially reverses some plastic changes that may be adaptive in non-stepping paraplegia after SCI. PMID:25948267

  20. Extrastriate visual cortex reorganizes despite sequential bilateral occipital stroke: implications for vision recovery

    Directory of Open Access Journals (Sweden)

    Amy eBrodtmann

    2015-04-01

    Full Text Available The extent of visual cortex reorganization following injury remains controversial. We report serial functional magnetic resonance imaging (fMRI data from a patient with sequential posterior circulation strokes occurring three weeks apart, compared with data from an age-matched healthy control subject. At 8 days following a left occipital stroke, contralesional visual cortical activation was within expected striate and extrastriate sites, comparable to that seen in controls. Despite a further infarct in the right (previously unaffected hemisphere, there was evolution of visual cortical reorganization progressed. In this patient, there was evidence of utilization of peri-infarct sites (right-sided and recruitment of new activation sites in extrastriate cortices, including in the lateral middle and inferior temporal lobes. The changes over time corresponded topographically with the patient’s lesion site and its connections. Reorganization of the surviving visual cortex was demonstrated 8 days after the first stroke. Ongoing reorganization in extant cortex was demonstrated at the 6 month scan. We present a summary of mechanisms of recovery following stroke relevant to the visual system. We conclude that mature primary visual cortex displays considerable plasticity and capacity to reorganize, associated with evolution of visual field deficits. We discuss these findings and their implications for therapy within the context of current concepts in visual compensatory and restorative therapies.

  1. Extrastriate visual cortex reorganizes despite sequential bilateral occipital stroke: implications for vision recovery.

    Science.gov (United States)

    Brodtmann, Amy; Puce, Aina; Darby, David; Donnan, Geoffrey

    2015-01-01

    The extent of visual cortex reorganization following injury remains controversial. We report serial functional magnetic resonance imaging (fMRI) data from a patient with sequential posterior circulation strokes occurring 3 weeks apart, compared with data from an age-matched healthy control subject. At 8 days following a left occipital stroke, contralesional visual cortical activation was within expected striate and extrastriate sites, comparable to that seen in controls. Despite a further infarct in the right (previously unaffected hemisphere), there was evolution of visual cortical reorganization progressed. In this patient, there was evidence of utilization of peri-infarct sites (right-sided) and recruitment of new activation sites in extrastriate cortices, including in the lateral middle and inferior temporal lobes. The changes over time corresponded topographically with the patient's lesion site and its connections. Reorganization of the surviving visual cortex was demonstrated 8 days after the first stroke. Ongoing reorganization in extant cortex was demonstrated at the 6 month scan. We present a summary of mechanisms of recovery following stroke relevant to the visual system. We conclude that mature primary visual cortex displays considerable plasticity and capacity to reorganize, associated with evolution of visual field deficits. We discuss these findings and their implications for therapy within the context of current concepts in visual compensatory and restorative therapies.

  2. State- and trait-related alterations of motor cortex excitability in tinnitus patients.

    Directory of Open Access Journals (Sweden)

    Martin Schecklmann

    Full Text Available Chronic tinnitus is a brain network disorder with involvement of auditory and non-auditory areas. Repetitive transcranial magnetic stimulation (rTMS over the temporal cortex has been investigated for the treatment of tinnitus. Several small studies suggest that motor cortex excitability is altered in people with tinnitus. We retrospectively analysed data from 231 patients with chronic tinnitus and 120 healthy controls by pooling data from different studies. Variables of interest were resting motor threshold (RMT, short-interval intra-cortical inhibition (SICI, intra-cortical facilitation (ICF, and cortical silent period (CSP. 118 patients were tested twice - before and after ten rTMS treatment sessions over the left temporal cortex. In tinnitus patients SICI and ICF were increased and CSP was shortened as compared to healthy controls. There was no group difference in RMT. Treatment related amelioration of tinnitus symptoms were correlated with normalisations in SICI. These findings confirm earlier studies of abnormal motor cortex excitability in tinnitus patients. Moreover our longitudinal data suggest that altered SICI may reflect a state parameter, whereas CSP and ICF may rather mirror a trait-like predisposing factor of tinnitus. These findings are new and innovative as they enlarge the knowledge about basic physiologic and neuroplastic processes in tinnitus.

  3. Effects of Bilateral Electrolytic Lesions of the Dorsomedial Striatum on Motor Behavior and Instrumental Learning in Rats

    Directory of Open Access Journals (Sweden)

    Pamphyle Abedi Mukutenga

    2012-09-01

    Full Text Available Introduction: The dorsal striatum plays an important role in the control of motor activity and learning processes within the basal ganglia circuitry. Furthermore, recent works have suggested functional differentiation between subregions of the dorsal striatumMethods:The present study examined the effects of bilateral electrolytic lesions of the dorsomedial striatum on motor behavior and learning ability in rats using a series of behavioral tests. 20 male wistar rats were used in the experiment and behavioral assessment were conducted using open field test, rotarod test and 8-arm radial maze.Results:In the open field test, rats with bilateral electrolytic lesions of the dorsomedial striatum showed a normal motor function in the horizontal locomotor activity, while in rearing activity they displayed a statistically significant motor impairment when compared to sham operated group. In the rotarod test, a deficit in motor coordination and acquisition of skilled behavior was observed in rats with bilateral electrolytic lesions of the dorsomedial striatum compared to sham. However, radial maze performance revealed similar capacity in the acquisition of learning task between experimental groups.Discussion:Our results support the premise of the existence of functional dissociation between the dorsomedial and the dorsolateral regions of the dorsal striatum. In addition, our data suggest that the associative dorsomedial striatum may be as critical in striatum-based motor control.

  4. Aberrant neuromagnetic activation in the motor cortex in children with acute migraine: a magnetoencephalography study.

    Science.gov (United States)

    Guo, Xinyao; Xiang, Jing; Wang, Yingying; O'Brien, Hope; Kabbouche, Marielle; Horn, Paul; Powers, Scott W; Hershey, Andrew D

    2012-01-01

    Migraine attacks have been shown to interfere with normal function in the brain such as motor or sensory function. However, to date, there has been no clinical neurophysiology study focusing on the motor function in children with migraine during headache attacks. To investigate the motor function in children with migraine, twenty-six children with acute migraine, meeting International Classification of Headache Disorders criteria and age- and gender-matched healthy children were studied using a 275-channel magnetoencephalography system. A finger-tapping paradigm was designed to elicit neuromagnetic activation in the motor cortex. Children with migraine showed significantly prolonged latency of movement-evoked magnetic fields (MEF) during finger movement compared with the controls. The correlation coefficient of MEF latency and age in children with migraine was significantly different from that in healthy controls. The spectral power of high gamma (65-150 Hz) oscillations during finger movement in the primary motor cortex is also significantly higher in children with migraine than in controls. The alteration of responding latency and aberrant high gamma oscillations suggest that the developmental trajectory of motor function in children with migraine is impaired during migraine attacks and/or developmentally delayed. This finding indicates that childhood migraine may affect the development of brain function and result in long-term problems.

  5. Aberrant neuromagnetic activation in the motor cortex in children with acute migraine: a magnetoencephalography study.

    Directory of Open Access Journals (Sweden)

    Xinyao Guo

    Full Text Available Migraine attacks have been shown to interfere with normal function in the brain such as motor or sensory function. However, to date, there has been no clinical neurophysiology study focusing on the motor function in children with migraine during headache attacks. To investigate the motor function in children with migraine, twenty-six children with acute migraine, meeting International Classification of Headache Disorders criteria and age- and gender-matched healthy children were studied using a 275-channel magnetoencephalography system. A finger-tapping paradigm was designed to elicit neuromagnetic activation in the motor cortex. Children with migraine showed significantly prolonged latency of movement-evoked magnetic fields (MEF during finger movement compared with the controls. The correlation coefficient of MEF latency and age in children with migraine was significantly different from that in healthy controls. The spectral power of high gamma (65-150 Hz oscillations during finger movement in the primary motor cortex is also significantly higher in children with migraine than in controls. The alteration of responding latency and aberrant high gamma oscillations suggest that the developmental trajectory of motor function in children with migraine is impaired during migraine attacks and/or developmentally delayed. This finding indicates that childhood migraine may affect the development of brain function and result in long-term problems.

  6. Continuous theta-burst stimulation of the primary motor cortex in essential tremor.

    Science.gov (United States)

    Hellriegel, Helge; Schulz, Eva M; Siebner, Hartwig R; Deuschl, Günther; Raethjen, Jan H

    2012-05-01

    We investigated whether essential tremor (ET) can be altered by suppressing the corticospinal excitability in the primary motor cortex (M1) with transcranial magnetic stimulation. 10 Patients with ET and 10 healthy controls underwent transcranial continuous theta-burst stimulation (cTBS) of the left primary motor hand area at 80% (real cTBS) and 30% (control cTBS) of active motor threshold in two separate sessions at least one week apart. Postural tremor was rated clinically and measured accelerometrically before and after cTBS. Corticospinal excitability was assessed by recording the motor evoked potentials (MEP) from the first dorsal interosseous muscle. Real cTBS but not control cTBS reduced the tremor total power assessed with accelerometry. This beneficial effect was subclinical as there were no significant changes in clinical tremor rating after real cTBS. Relative to control cTBS, real cTBS reduced corticospinal excitability in the stimulated primary motor cortex only in healthy controls but not in ET patients. Real cTBS has a beneficial effect on ET. Since cTBS did not induce a parallel reduction in corticospinal excitability, this effect was not mediated by a suppression of the corticospinal motor output. "Inhibitory" cTBS of M1 leads to a consistent but subclinical reduction in tremor amplitude. Copyright © 2011 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  7. Neuronal injury in the motor cortex after chronic stroke and lower limb motor impairment:a voxel-based lesion symptom mapping study

    Institute of Scientific and Technical Information of China (English)

    Alexandria M. Reynolds; Denise M. Peters; Jennifer M. C. Vendemia; Lenwood P. Smith; Raymond C. Sweet; Gordon C. Baylis; Debra Krotish; Stacy L Fritz

    2014-01-01

    Many studies have examined motor impairments using voxel-based lesion symptom mapping, but few are reported regarding the corresponding relationship between cerebral cortex injury and lower limb motor impairment analyzed using this technique. This study correlated neuro-nal injury in the cerebral cortex of 16 patients with chronic stroke based on a voxel-based lesion symptom mapping analysis. Neuronal injury in the corona radiata, caudate nucleus and putamen of patients with chronic stroke could predict walking speed. The behavioral measure scores were consistent with motor deifcits expected after damage to the cortical motor system due to stroke. These ifndings suggest that voxel-based lesion symptom mapping may provide a more accurate prognosis of motor recovery from chronic stroke according to neuronal injury in cerebral motor cortex.

  8. Visual spatial attention has opposite effects on bidirectional plasticity in the human motor cortex.

    Science.gov (United States)

    Kamke, Marc R; Ryan, Alexander E; Sale, Martin V; Campbell, Megan E J; Riek, Stephan; Carroll, Timothy J; Mattingley, Jason B

    2014-01-22

    Long-term potentiation (LTP) and long-term depression (LTD) are key mechanisms of synaptic plasticity that are thought to act in concert to shape neural connections. Here we investigated the influence of visual spatial attention on LTP-like and LTD-like plasticity in the human motor cortex. Plasticity was induced using paired associative stimulation (PAS), which involves repeated pairing of peripheral nerve stimulation and transcranial magnetic stimulation to alter functional responses in the thumb area of the primary motor cortex. PAS-induced changes in cortical excitability were assessed using motor-evoked potentials. During plasticity induction, participants directed their attention to one of two visual stimulus streams located adjacent to each hand. When participants attended to visual stimuli located near the left thumb, which was targeted by PAS, LTP-like increases in excitability were significantly enhanced, and LTD-like decreases in excitability reduced, relative to when they attended instead to stimuli located near the right thumb. These differential effects on (bidirectional) LTP-like and LTD-like plasticity suggest that voluntary visual attention can exert an important influence on the functional organization of the motor cortex. Specifically, attention acts to both enhance the strengthening and suppress the weakening of neural connections representing events that fall within the focus of attention.

  9. Properties and fate of oligodendrocyte progenitor cells in the corpus callosum, motor cortex, and piriform cortex of the mouse.

    Science.gov (United States)

    Clarke, Laura E; Young, Kaylene M; Hamilton, Nicola B; Li, Huiliang; Richardson, William D; Attwell, David

    2012-06-13

    Oligodendrocyte progenitor cells (OPCs) in the postnatal mouse corpus callosum (CC) and motor cortex (Ctx) reportedly generate only oligodendrocytes (OLs), whereas those in the piriform cortex may also generate neurons. OPCs have also been subdivided based on their expression of voltage-gated ion channels, ability to respond to neuronal activity, and proliferative state. To determine whether OPCs in the piriform cortex have inherently different physiological properties from those in the CC and Ctx, we studied acute brain slices from postnatal transgenic mice in which GFP expression identifies OL lineage cells. We whole-cell patch clamped GFP-expressing (GFP(+)) cells within the CC, Ctx, and anterior piriform cortex (aPC) and used prelabeling with 5-ethynyl-2'-deoxyuridine (EdU) to assess cell proliferation. After recording, slices were immunolabeled and OPCs were defined by strong expression of NG2. NG2(+) OPCs in the white and gray matter proliferated and coexpressed PDGFRα and voltage-gated Na(+) channels (I(Na)). Approximately 70% of OPCs were capable of generating regenerative depolarizations. In addition to OLIG2(+) NG2(+) I(Na)(+) OPCs and OLIG2(+) NG2(neg) I(Na)(neg) OLs, we identified cells with low levels of NG2 limited to the soma or the base of some processes. These cells had a significantly reduced I(Na) and a reduced ability to incorporate EdU when compared with OPCs and probably correspond to early differentiating OLs. By combining EdU labeling and lineage tracing using Pdgfrα-CreER(T2) : R26R-YFP transgenic mice, we double labeled OPCs and traced their fate in the postnatal brain. These OPCs generated OLs but did not generate neurons in the aPC or elsewhere at any time that we examined.

  10. The Assessment of Postural Control, Reflex Integration, and Bilateral Motor Coordination of Young Handicapped Children. Final Report.

    Science.gov (United States)

    DeGangi, Georgia; Larsen, Lawrence A.

    A measurement device, Assessment of Sensorimotor Integration in Preschool Children, was developed to assess postural control, reflex integration and bilateral motor integration in developmentally delayed children (3 to 5 years old). The test was administered to 113 normal children and results were compared with data collected on 23 developmentally…

  11. Visual Feedback of Bilateral Bite Force to Assess Motor Control of the Mandible in Isometric Condition.

    Science.gov (United States)

    Testa, Marco; Geri, Tommaso; Signori, Alessio; Roatta, Silvestro

    2015-10-01

    The assessment of the individual ability of modulating and coordinating the right and left bite force is poorly investigated. The present study describes a methodology for the assessment of the bilateral control of the biting force and evaluates the test-retest reliability in a sample of 13 healthy subjects. By modulating the intensity and the left/right balance of the biting force, the subject was able to drive a cursor on the screen to "reach and hold" targets, randomly generated within the physiological "range of force" of the subject. The average motor performance was evaluated by the mean cursor-target distance = 13 ± 5%, the Offset Error = 9 ± 5% and the standard deviation of the force vector = 17.7 ± 6.1% (expressed as % of the target). Mean distance and standard deviation indices had acceptable reliability. This technique improves the characterization of the mandibular motor function and it may have a relevant role for the assessment and rehabilitation of the neuromusculoskeletal disorders affecting the orofacial system.

  12. Sentential context modulates the involvement of the motor cortex in action language processing: an FMRI study.

    Science.gov (United States)

    Schuil, Karen D I; Smits, Marion; Zwaan, Rolf A

    2013-01-01

    Theories of embodied cognition propose that language comprehension is based on perceptual and motor processes. More specifically, it is hypothesized that neurons processing verbs describing bodily actions, and those that process the corresponding physical actions, fire simultaneously during action verb learning. Thus the concept and motor activation become strongly linked. According to this view, the language-induced activation of the neural substrates for action is automatic. By contrast, a weak view of embodied cognition proposes that activation of these motor regions is modulated by context. In recent studies it was found that action verbs in literal sentences activate the motor system, while mixed results were observed for action verbs in non-literal sentences. Thus, whether the recruitment of motor regions is automatic or context dependent remains a question. We investigated functional magnetic resonance imaging activation in response to non-literal and literal sentences including arm and leg related actions. The sentence structure was such that the action verb was the last word in the subordinate clause. Thus, the constraining context was presented well before the verb. Region of interest analyses showed that action verbs in literal context engage the motor regions to a greater extent than non-literal action verbs. There was no evidence for a semantic somatotopic organization of the motor cortex. Taken together, these results indicate that during comprehension, the degree to which motor regions are recruited is context dependent, supporting the weak view of embodied cognition.

  13. Influence of position and stimulation parameters on intracortical inhibition and facilitation in human tongue motor cortex

    DEFF Research Database (Denmark)

    Kothari, Mohit; Svensson, Peter; Nielsen, Jørgen Feldbæk;

    2014-01-01

    and supine), inter-stimulus intervals (ISI) between the test stimulus (TS) and conditioning stimulus (CS) and intensities of the TS and CS on the degree of SICI and ICF. In study 1 and 2, fourteen and seventeen healthy volunteers participated respectively. ppTMS was applied over the "hot-spot" of the tongue...... motor cortex and motor evoked potentials (MEPs) were recorded from contralateral tongue muscles. In study 1, single pulse and three ppTMS ISIs: 2, 10, 15 ms were applied 8 times each in three blocks (TS: 120%, 140% and 160% of resting motor threshold (rMT); CS: 80% of rMT) in two different body.......001) and interaction between intensity and ISIs (P=0.042) in study 1. In study 2, there was a significant effect of ISI (Ptongue motor pathways using ppTMS and SICI...

  14. Intermanual transfer and bilateral cortical plasticity is maintained in older adults after skilled motor training with simple and complex tasks

    Science.gov (United States)

    Dickins, Daina S. E.; Sale, Martin V.; Kamke, Marc R.

    2015-01-01

    Intermanual transfer refers to the phenomenon whereby unilateral motor training induces performance gains in both the trained limb and in the opposite, untrained limb. Evidence indicates that intermanual transfer is attenuated in older adults following training on a simple ballistic movement task, but not after training on a complex task. This study investigated whether differences in plasticity in bilateral motor cortices underlie these differential intermanual transfer effects in older adults. Twenty young (65 years) trained on a simple (repeated ballistic thumb abduction) and complex (sequential finger-thumb opposition) task in separate sessions. Behavioral performance was used to quantify intermanual transfer between the dominant (trained) and non-dominant (untrained) hands. The amplitude of motor-evoked potentials induced by single pulse transcranial magnetic stimulation was used to investigate excitability changes in bilateral motor cortices. Contrary to predictions, both age groups exhibited performance improvements in both hands after unilateral skilled motor training with simple and complex tasks. These performance gains were accompanied by bilateral increases in cortical excitability in both groups for the simple but not the complex task. The findings suggest that advancing age does not necessarily influence the capacity for intermanual transfer after training with the dominant hand. PMID:25999856

  15. Intermanual transfer and bilateral cortical plasticity is maintained in older adults after skilled motor training with simple and complex tasks.

    Science.gov (United States)

    Dickins, Daina S E; Sale, Martin V; Kamke, Marc R

    2015-01-01

    Intermanual transfer refers to the phenomenon whereby unilateral motor training induces performance gains in both the trained limb and in the opposite, untrained limb. Evidence indicates that intermanual transfer is attenuated in older adults following training on a simple ballistic movement task, but not after training on a complex task. This study investigated whether differences in plasticity in bilateral motor cortices underlie these differential intermanual transfer effects in older adults. Twenty young (65 years) trained on a simple (repeated ballistic thumb abduction) and complex (sequential finger-thumb opposition) task in separate sessions. Behavioral performance was used to quantify intermanual transfer between the dominant (trained) and non-dominant (untrained) hands. The amplitude of motor-evoked potentials induced by single pulse transcranial magnetic stimulation was used to investigate excitability changes in bilateral motor cortices. Contrary to predictions, both age groups exhibited performance improvements in both hands after unilateral skilled motor training with simple and complex tasks. These performance gains were accompanied by bilateral increases in cortical excitability in both groups for the simple but not the complex task. The findings suggest that advancing age does not necessarily influence the capacity for intermanual transfer after training with the dominant hand.

  16. Intermanual transfer and bilateral cortical plasticity is maintained in older adults after skilled motor training with simple and complex tasks

    Directory of Open Access Journals (Sweden)

    Daina S. E. Dickins

    2015-05-01

    Full Text Available Intermanual transfer refers to the phenomenon whereby unilateral motor training induces performance gains in both the trained limb and in the opposite, untrained limb. Evidence indicates that intermanual transfer is attenuated in older adults following training on a simple ballistic movement task, but not after training on a complex task. This study investigated whether differences in plasticity in bilateral motor cortices underlie these differential intermanual transfer effects in older adults. Twenty young (65 years trained on a simple (repeated ballistic thumb abduction and complex (sequential finger-thumb opposition task in separate sessions. Behavioral performance was used to quantify intermanual transfer between the dominant (trained and non-dominant (untrained hands. The amplitude of motor-evoked potentials (MEPs induced by single pulse transcranial magnetic stimulation (TMS was used to investigate excitability changes in bilateral motor cortices. Contrary to predictions, both age groups exhibited performance improvements in both hands after unilateral skilled motor training with simple and complex tasks. These performance gains were accompanied by bilateral increases in cortical excitability in both groups for the simple but not the complex task. The findings suggest that advancing age does not necessarily influence the capacity for intermanual transfer after training with the dominant hand.

  17. Parallel pathways from motor and somatosensory cortex for controlling whisker movements in mice.

    Science.gov (United States)

    Sreenivasan, Varun; Karmakar, Kajari; Rijli, Filippo M; Petersen, Carl C H

    2015-02-01

    Mice can gather tactile sensory information by actively moving their whiskers to palpate objects in their immediate surroundings. Whisker sensory perception therefore requires integration of sensory and motor information, which occurs prominently in the neocortex. The signalling pathways from the neocortex for controlling whisker movements are currently poorly understood in mice. Here, we delineate two pathways, one originating from primary whisker somatosensory cortex (wS1) and the other from whisker motor cortex (wM1), that control qualitatively distinct movements of contralateral whiskers. Optogenetic stimulation of wS1 drove retraction of contralateral whiskers while stimulation of wM1 drove rhythmic whisker protraction. To map brainstem pathways connecting these cortical areas to whisker motor neurons, we used a combination of anterograde tracing using adenoassociated virus injected into neocortex and retrograde tracing using monosynaptic rabies virus injected into whisker muscles. Our data are consistent with wS1 driving whisker retraction by exciting glutamatergic premotor neurons in the rostral spinal trigeminal interpolaris nucleus, which in turn activate the motor neurons innervating the extrinsic retractor muscle nasolabialis. The rhythmic whisker protraction evoked by wM1 stimulation might be driven by excitation of excitatory and inhibitory premotor neurons in the brainstem reticular formation innervating both intrinsic and extrinsic muscles. Our data therefore begin to unravel the neuronal circuits linking the neocortex to whisker motor neurons. © 2014 The Authors. European Journal of Neuroscience published by Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  18. Intracortical Microstimulation Maps of Motor, Somatosensory, and Posterior Parietal Cortex in Tree Shrews (Tupaia belangeri) Reveal Complex Movement Representations.

    Science.gov (United States)

    Baldwin, Mary K L; Cooke, Dylan F; Krubitzer, Leah

    2016-01-11

    Long-train intracortical microstimulation (LT-ICMS) is a popular method for studying the organization of motor and posterior parietal cortex (PPC) in mammals. In primates, LT-ICMS evokes both multijoint and multiple-body-part movements in primary motor, premotor, and PPC. In rodents, LT-ICMS evokes complex movements of a single limb in motor cortex. Unfortunately, very little is known about motor/PPC organization in other mammals. Tree shrews are closely related to both primates and rodents and could provide insights into the evolution of complex movement domains in primates. The present study investigated the extent of cortex in which movements could be evoked with ICMS and the characteristics of movements elicited using both short train (ST) and LT-ICMS in tree shrews. We demonstrate that LT-ICMS and ST-ICMS maps are similar, with the movements elicited with ST-ICMS being truncated versions of those elicited with LT-ICMS. In addition, LT-ICMS-evoked complex movements within motor cortex similar to those in rodents. More complex movements involving multiple body parts such as the hand and mouth were also elicited in motor cortex and PPC, as in primates. Our results suggest that complex movement networks present in PPC and motor cortex were present in mammals prior to the emergence of primates.

  19. Metabolic Changes in the Bilateral Visual Cortex of the Monocular Blind Macaque: A Multi-Voxel Proton Magnetic Resonance Spectroscopy Study.

    Science.gov (United States)

    Wu, Lingjie; Tang, Zuohua; Feng, Xiaoyuan; Sun, Xinghuai; Qian, Wen; Wang, Jie; Jin, Lixin; Jiang, Jingxuan; Zhong, Yufeng

    2017-02-01

    The metabolic changes accompanied with adaptive plasticity in the visual cortex after early monocular visual loss were unclear. In this study, we detected the metabolic changes in bilateral visual cortex of normal (group A) and monocular blind macaque (group B) for studying the adaptive plasticity using multi-voxel proton magnetic resonance spectroscopy ((1)H-MRS) at 32 months after right optic nerve transection. Then, we compared the N-Acetyl aspartate (NAA)/Creatine (Cr), myoinositol (Ins)/Cr, choline (Cho)/Cr and Glx (Glutamate + glutamine)/Cr ratios in the visual cortex between two groups, as well as between the left and right visual cortex of group A and B. Compared with group A, in the bilateral visual cortex, a decreased NAA/Cr and Glx/Cr ratios in group B were found, which was more clearly in the right visual cortex; whereas the Ins/Cr and Cho/Cr ratios of group B were increased. All of these findings were further confirmed by immunohistochemical staining. In conclusion, the difference of metabolic ratios can be detected by multi-voxel (1)H-MRS in the visual cortex between groups A and B, which was valuable for investigating the adaptive plasticity of monocular blind macaque.

  20. Complex regional pain syndrome type I affects brain structure in prefrontal and motor cortex.

    Directory of Open Access Journals (Sweden)

    Burkhard Pleger

    Full Text Available The complex regional pain syndrome (CRPS is a rare but debilitating pain disorder that mostly occurs after injuries to the upper limb. A number of studies indicated altered brain function in CRPS, whereas possible influences on brain structure remain poorly investigated. We acquired structural magnetic resonance imaging data from CRPS type I patients and applied voxel-by-voxel statistics to compare white and gray matter brain segments of CRPS patients with matched controls. Patients and controls were statistically compared in two different ways: First, we applied a 2-sample ttest to compare whole brain white and gray matter structure between patients and controls. Second, we aimed to assess structural alterations specifically of the primary somatosensory (S1 and motor cortex (M1 contralateral to the CRPS affected side. To this end, MRI scans of patients with left-sided CRPS (and matched controls were horizontally flipped before preprocessing and region-of-interest-based group comparison. The unpaired ttest of the "non-flipped" data revealed that CRPS patients presented increased gray matter density in the dorsomedial prefrontal cortex. The same test applied to the "flipped" data showed further increases in gray matter density, not in the S1, but in the M1 contralateral to the CRPS-affected limb which were inversely related to decreased white matter density of the internal capsule within the ipsilateral brain hemisphere. The gray-white matter interaction between motor cortex and internal capsule suggests compensatory mechanisms within the central motor system possibly due to motor dysfunction. Altered gray matter structure in dorsomedial prefrontal cortex may occur in response to emotional processes such as pain-related suffering or elevated analgesic top-down control.

  1. Complex regional pain syndrome type I affects brain structure in prefrontal and motor cortex.

    Science.gov (United States)

    Pleger, Burkhard; Draganski, Bogdan; Schwenkreis, Peter; Lenz, Melanie; Nicolas, Volkmar; Maier, Christoph; Tegenthoff, Martin

    2014-01-01

    The complex regional pain syndrome (CRPS) is a rare but debilitating pain disorder that mostly occurs after injuries to the upper limb. A number of studies indicated altered brain function in CRPS, whereas possible influences on brain structure remain poorly investigated. We acquired structural magnetic resonance imaging data from CRPS type I patients and applied voxel-by-voxel statistics to compare white and gray matter brain segments of CRPS patients with matched controls. Patients and controls were statistically compared in two different ways: First, we applied a 2-sample ttest to compare whole brain white and gray matter structure between patients and controls. Second, we aimed to assess structural alterations specifically of the primary somatosensory (S1) and motor cortex (M1) contralateral to the CRPS affected side. To this end, MRI scans of patients with left-sided CRPS (and matched controls) were horizontally flipped before preprocessing and region-of-interest-based group comparison. The unpaired ttest of the "non-flipped" data revealed that CRPS patients presented increased gray matter density in the dorsomedial prefrontal cortex. The same test applied to the "flipped" data showed further increases in gray matter density, not in the S1, but in the M1 contralateral to the CRPS-affected limb which were inversely related to decreased white matter density of the internal capsule within the ipsilateral brain hemisphere. The gray-white matter interaction between motor cortex and internal capsule suggests compensatory mechanisms within the central motor system possibly due to motor dysfunction. Altered gray matter structure in dorsomedial prefrontal cortex may occur in response to emotional processes such as pain-related suffering or elevated analgesic top-down control.

  2. Association between the fMRI manifestations of activated brain areas and muscle strength in patients with space-occupying lesions in motor cortex

    Institute of Scientific and Technical Information of China (English)

    Wenbin Zheng; Xiaoke Chen; Guorui Liu; Renhua Wu

    2006-01-01

    simple active finger-tapping movements, and for the 3 cases whose clinical symptoms were severe in the patient group, the simple passive finger-tapping movements were used. The manifestations in the activated brain areas were analyzed in the patients with brain tumor of different muscle strength and the controls. The motor deficit and activation of contralateral primary motor cortex (M1) in simple finger-tapping movements were observed in the patient group.MAIN OUTCOME MEASURES: ① Brain areas activated by finger-tapping movements in each group; ② Activated volumes in hemisphere by finger-tapping movements between groups.RESULTS: The contralateral M1 area could not be activated in 1 case in the patient group,, all the other 22 patients and 9 healthy subjects were involved in the analysis of results. ① In the control group, unilateral finger tapping movement activated the contralateral primary motor cortex (M1), bilateral SMA and bilateral PMC. The activation volume was the largest in contralateral primary motor cortex (M1), smaller in the SMA,and the smallest in PMC. The finger tapping movement in healthy subjects could activate contralateral primary motor cortex (M1), bilateral SMA and bilateral PMC, which had no obvious differences from the manifestations of brain functional area activated by active finger tapping. There was no significant difference in the volume of activated functional areas between right and left hands. In the patient group, the central sulcus around the tumor in the activated M1 area displaced towards dorsal or ventral side, also extended. The distance of displacement in the functional area was determined as compared with the contralateral central sulcus, and the results suggested the M1 displacement, including that there were 10 cases with the M1 displacement larger than 10 mm in the patients with motor deficit, which were obviously more than in those without motor deficit (n =1, P < 0.01), and the activated volume in contralateral M1 area

  3. Cortico-fugal output from visual cortex promotes plasticity of innate motor behaviour.

    Science.gov (United States)

    Liu, Bao-Hua; Huberman, Andrew D; Scanziani, Massimo

    2016-10-20

    The mammalian visual cortex massively innervates the brainstem, a phylogenetically older structure, via cortico-fugal axonal projections. Many cortico-fugal projections target brainstem nuclei that mediate innate motor behaviours, but the function of these projections remains poorly understood. A prime example of such behaviours is the optokinetic reflex (OKR), an innate eye movement mediated by the brainstem accessory optic system, that stabilizes images on the retina as the animal moves through the environment and is thus crucial for vision. The OKR is plastic, allowing the amplitude of this reflex to be adaptively adjusted relative to other oculomotor reflexes and thereby ensuring image stability throughout life. Although the plasticity of the OKR is thought to involve subcortical structures such as the cerebellum and vestibular nuclei, cortical lesions have suggested that the visual cortex might also be involved. Here we show that projections from the mouse visual cortex to the accessory optic system promote the adaptive plasticity of the OKR. OKR potentiation, a compensatory plastic increase in the amplitude of the OKR in response to vestibular impairment, is diminished by silencing visual cortex. Furthermore, targeted ablation of a sparse population of cortico-fugal neurons that specifically project to the accessory optic system severely impairs OKR potentiation. Finally, OKR potentiation results from an enhanced drive exerted by the visual cortex onto the accessory optic system. Thus, cortico-fugal projections to the brainstem enable the visual cortex, an area that has been principally studied for its sensory processing function, to plastically adapt the execution of innate motor behaviours.

  4. Fezf2 expression in layer 5 projection neurons of mature mouse motor cortex.

    Science.gov (United States)

    Tantirigama, Malinda L S; Oswald, Manfred J; Clare, Alison J; Wicky, Hollie E; Day, Robert C; Hughes, Stephanie M; Empson, Ruth M

    2016-03-01

    The mature cerebral cortex contains a wide diversity of neuron phenotypes. This diversity is specified during development by neuron-specific expression of key transcription factors, some of which are retained for the life of the animal. One of these key developmental transcription factors that is also retained in the adult is Fezf2, but the neuron types expressing it in the mature cortex are unknown. With a validated Fezf2-Gfp reporter mouse, whole-cell electrophysiology with morphology reconstruction, cluster analysis, in vivo retrograde labeling, and immunohistochemistry, we identify a heterogeneous population of Fezf2(+) neurons in both layer 5A and layer 5B of the mature motor cortex. Functional electrophysiology identified two distinct subtypes of Fezf2(+) neurons that resembled pyramidal tract projection neurons (PT-PNs) and intratelencephalic projection neurons (IT-PNs). Retrograde labeling confirmed the former type to include corticospinal projection neurons (CSpPNs) and corticothalamic projection neurons (CThPNs), whereas the latter type included crossed corticostriatal projection neurons (cCStrPNs) and crossed-corticocortical projection neurons (cCCPNs). The two Fezf2(+) subtypes expressed either CTIP2 or SATB2 to distinguish their physiological identity and confirmed that specific expression combinations of key transcription factors persist in the mature motor cortex. Our findings indicate a wider role for Fezf2 within gene expression networks that underpin the diversity of layer 5 cortical projection neurons.

  5. Hemispheric asymmetry in cerebrovascular reactivity of the human primary motor cortex: an in vivo study at 7 T.

    Science.gov (United States)

    Driver, Ian D; Andoh, Jamila; Blockley, Nicholas P; Francis, Susan T; Gowland, Penny A; Paus, Tomáš

    2015-05-01

    Current functional MRI (fMRI) approaches assess underlying neuronal activity through monitoring the related local variations in cerebral blood oxygenation, blood volume and blood flow. This vascular response is likely to vary across brain regions and across individuals, depending on the composition of the local vascular bed and on the vascular capacity to dilate. The most widely used technique uses the blood oxygen level dependent (BOLD) fMRI signal, which arises from a complex combination of all of these factors. The model of handedness provides a case where one brain region (dominant motor cortex) is known to have a stronger BOLD response over another (non-dominant motor cortex) during hand motor task performance. We predict that this is accompanied by a higher vascular reactivity in the dominant motor cortex, when compared with the non-dominant motor cortex. Precise measurement of end-tidal CO2 and a novel sinusoidal CO2 respiratory challenge were combined with the high sensitivity and finer spatial resolution available for fMRI at 7 T to measure BOLD cerebrovascular reactivity (CVR) in eight healthy male participants. BOLD CVR was compared between the left (dominant) and right (non-dominant) primary motor cortices of right-handed adults. Hemispheric asymmetry in vascular reactivity was predicted and observed in the primary motor cortex (left CVR = 0.60 ± 0.15%/mm Hg; right CVR = 0.47 ± 0.08%/mm Hg; left CVR > right CVR, P = 0.04), the first reported evidence of such a vascular difference. These findings demonstrate a cerebral vascular asymmetry between the left and right primary motor cortex. The origin of this asymmetry largely arises from the contribution of large draining veins. This work has implications for future motor laterality studies that use BOLD, and it is also suggestive of a vascular plasticity in the human primary motor cortex.

  6. Temporal dynamics of motor cortex excitability during perception of natural emotional scenes.

    Science.gov (United States)

    Borgomaneri, Sara; Gazzola, Valeria; Avenanti, Alessio

    2014-10-01

    Although it is widely assumed that emotions prime the body for action, the effects of visual perception of natural emotional scenes on the temporal dynamics of the human motor system have scarcely been investigated. Here, we used single-pulse transcranial magnetic stimulation (TMS) to assess motor excitability during observation and categorization of positive, neutral and negative pictures from the International Affective Picture System database. Motor-evoked potentials (MEPs) from TMS of the left motor cortex were recorded from hand muscles, at 150 and 300 ms after picture onset. In the early temporal condition we found an increase in hand motor excitability that was specific for the perception of negative pictures. This early negative bias was predicted by interindividual differences in the disposition to experience aversive feelings (personal distress) in interpersonal emotional contexts. In the later temporal condition, we found that MEPs were similarly increased for both positive and negative pictures, suggesting an increased reactivity to emotionally arousing scenes. By highlighting the temporal course of motor excitability during perception of emotional pictures, our study provides direct neurophysiological support for the evolutionary notions that emotion perception is closely linked to action systems and that emotionally negative events require motor reactions to be more urgently mobilized. © The Author (2013). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

  7. Motor cortex stimulation reduces hyperalgesia in an animal model of central pain.

    Science.gov (United States)

    Lucas, Jessica M; Ji, Yadong; Masri, Radi

    2011-06-01

    Electrical stimulation of the primary motor cortex has been used since 1991 to treat chronic neuropathic pain. Since its inception, motor cortex stimulation (MCS) treatment has had varied clinical outcomes. Until this point, there has not been a systematic study of the stimulation parameters that most effectively treat chronic pain, or of the mechanisms by which MCS relieves pain. Here, using a rodent model of central pain, we perform a systematic study of stimulation parameters used for MCS and investigate the mechanisms by which MCS reduces hyperalgesia. Specifically, we study the role of the inhibitory nucleus zona incerta (ZI) in mediating the analgesic effects of MCS. In animals with mechanical and thermal hyperalgesia, we find that stimulation at 50 μA, 50 Hz, and 300 μs square pulses for 30 minutes is sufficient to reverse mechanical and thermal hyperalgesia. We also find that stimulation of the ZI mimics the effects of MCS and that reversible inactivation of ZI blocks the effects of MCS. These findings suggest that the reduction of hyperalgesia may be due to MCS effects on ZI. In an animal model of central pain syndrome, motor cortex stimulation reduces hyperalgesia by activating zona incerta and therefore restoring inhibition in the thalamus.

  8. Physical activity-associated gene expression signature in nonhuman primate motor cortex.

    Science.gov (United States)

    Mitchell, Amanda C; Leak, Rehana K; Garbett, Krassimira; Zigmond, Michael J; Cameron, Judy L; Mirnics, Károly

    2012-03-01

    It has been established that weight gain and weight loss are heavily influenced by activity level. In this study, we hypothesized that the motor cortex exhibits a distinct physical activity-associated gene expression profile, which may underlie changes in weight associated with movement. Using DNA microarrays we profiled gene expression in the motor cortex of a group of 14 female rhesus monkeys (Macaca mulatta) with a wide range of stable physical activity levels. We found that neuronal growth factor signaling and nutrient sensing transcripts in the brain were highly correlated with physical activity. A follow-up of AKT3 expression changes (a gene at the apex of neuronal survival and nutrient sensing) revealed increased protein levels of total AKT, phosphorylated AKT, and forkhead box O3 (FOXO3), one of AKT's main downstream effectors. In addition, we successfully validated three other genes via quantitative polymerase chain reaction (qPCR) (cereblon (CRBN), origin recognition complex subunit 4-like, and pyruvate dehydrogenase 4 (PDK4)). We conclude that these genes are important in the physical activity-associated pathway in the motor cortex, and may be critical for physical activity-associated changes in body weight and neuroprotection.

  9. Changes in sensory hand representation and pain thresholds induced by motor cortex stimulation in humans.

    Science.gov (United States)

    Houzé, Bérengère; Bradley, Claire; Magnin, Michel; Garcia-Larrea, Luis

    2013-11-01

    Shrinking of deafferented somatosensory regions after neural damage is thought to participate to the emergence of neuropathic pain, and pain-relieving procedures have been reported to induce the normalization of altered cortical maps. While repetitive magnetic stimulation (rTMS) of the motor cortex can lessen neuropathic pain, no evidence has been provided that this is concomitant to changes in sensory maps. Here, we assessed in healthy volunteers the ability of 2 modes of motor cortex rTMS commonly used in pain patients to induce changes in pain thresholds and plastic phenomena in the S1 cortex. Twenty minutes of high-frequency (20 Hz) rTMS significantly increased pain thresholds in the contralateral hand, and this was associated with the expansion of the cortical representation of the hand on high-density electroencephalogram source analysis. Neither of these effects were observed after sham rTMS, nor following intermittent theta-burst stimulation (iTBS). The superiority of 20-Hz rTMS over iTBS to induce sensory plasticity may reflect its better match with intrinsic cortical motor frequencies, which oscillate at around 20 Hz. rTMS-induced changes might partly counterbalance the plasticity induced by a nerve lesion, and thus substantiate the use of rTMS to treat human pain. However, a mechanistic relation between S1 plasticity and pain-relieving effects is far from being established.

  10. Reinstating the ability of the motor cortex to modulate cutaneomuscular reflexes in hemicerebellectomized rats.

    Science.gov (United States)

    Oulad Ben Taib, Nordeyn; Manto, Mario

    2008-04-14

    The pathways passing through the cerebellum calibrate cutaneomuscular responses. Indeed, the enhancement of cutaneomuscular responses associated with subthreshold high-frequency trains of stimulation applied on motor cortex following a period of peripheral repetitive stimulation (PRS) is prevented by hemicerebellectomy. We analysed the effects of low-frequency repetitive stimulation of motor cortex (LFRSM1) on interhemispheric inhibition (IHI) and on the modulation of cutaneomuscular reflexes in rats with left hemicerebellar ablation. IHI was assessed by paired-pulse method with a conditioning stimulus (CS) to M1 followed by a test stimulus (TS) to the opposite M1. LFRSM1 reduced IHI. Combination of LFRSM1 with PRS increased significantly the magnitudes of cutaneomuscular responses evoked ipsilaterally to the hemicerebellar ablation. The increase of the intensity of cutaneomuscular responses was correlated with the reduction of IHI. Excitability of anterior horn motoneurons pool, assessed by F-wave, remained unchanged. Conjunction of LFRSM1 with PRS can be used to restore the ability of the motor cortex to modulate the intensity of cutaneomuscular responses in case of extensive unilateral cerebellar lesion. This study underlines for the first time the potential role of callosal pathways in the deficits of corticomotor tuning of cutaneomuscular responses contralaterally to acute extensive cerebellar lesion.

  11. The neurophysiology of response competition: motor cortex activation and inhibition following subliminal response priming.

    Science.gov (United States)

    Praamstra, Peter; Seiss, Ellen

    2005-03-01

    Some widely used tasks in cognitive neuroscience depend on the induction of a response conflict between choice alternatives, involving partial activation of the incorrect response before the correct response is emitted. Although such ''conflict tasks'' are often used to investigate frontal-lobe-based conflict-monitoring processes, it is not known how response competition evolves in the motor cortex. To investigate the dynamics of motor cortex activation during response competition, we used a subliminal priming task that induced response competition while bypassing pre-response stage processing conflict. Analyses of movement-related EEG potentials supported an interaction between competing responses characterized by reciprocal inhibition. Inhibitory interactions between response channels contribute to the resolution of response conflict. However, the reciprocal inhibition at motor cortex level seemed to operate independent of higher level conflict-monitoring processes, which were relatively insensitive to response conflict induced by subliminal priming. These results elucidate how response conflict causes interference as well as the conditions under which frontal-lobe-based interference control processes are engaged.

  12. Efficacy and Interindividual Variability in Motor-Cortex Plasticity following Anodal tDCS and Paired-Associative Stimulation

    OpenAIRE

    Wolfgang Strube; Tilmann Bunse; Berend Malchow; Alkomiet Hasan

    2015-01-01

    Interindividual response variability to various motor-cortex stimulation protocols has been recently reported. Comparative data of stimulation protocols with different modes of action is lacking. We aimed to compare the efficacy and response variability of two LTP-inducing stimulation protocols in the human motor cortex: anodal transcranial direct current stimulation (a-tDCS) and paired-associative stimulation (PAS25). In two experiments 30 subjects received 1mA a-tDCS and PAS25. Data analysi...

  13. Different Effects of Implicit and Explicit Motor Sequence Learning on Latency of Motor Evoked Potential Evoked by Transcranial Magnetic Stimulation on the Primary Motor Cortex

    Science.gov (United States)

    Hirano, Masato; Kubota, Shinji; Koizume, Yoshiki; Tanaka, Shinya; Funase, Kozo

    2017-01-01

    Motor training induces plastic changes in the primary motor cortex (M1). However, it is unclear whether and how the latency of motor-evoked potentials (MEP) and MEP amplitude are affected by implicit and/or explicit motor learning. Here, we investigated the changes in M1 excitability and MEP latency induced by implicit and explicit motor learning. The subjects performed a serial reaction time task (SRTT) with their five fingers. In this task, visual cues were lit up sequentially along with a predetermined order. Through training, the subjects learned the order of sequence implicitly and explicitly. Before and after the SRTT, we recorded MEP at 25 stimulation points around the hot spot for the flexor pollicis brevis (FPB) muscle. Although no changes in MEP amplitude were observed in either session, we found increases in MEP latency and changes in histogram of MEP latency after implicit learning. Our results suggest that reorganization across the motor cortices occurs during the acquisition of implicit knowledge. In contrast, acquisition of explicit knowledge does not appear to induce the reorganization based on the measures we recorded. The fact that the above mentioned increases in MEP latency occurred without any alterations in MEP amplitude suggests that learning has different effects on different physiological signals. In conclusion, our results propose that analyzing a combination of some indices of M1 excitability, such as MEP amplitude and MEP latency, is encouraged in order to understand plasticity across motor cortices. PMID:28101014

  14. Motor adaptations to unilateral quadriceps fatigue during a bilateral pedaling task.

    Science.gov (United States)

    Brøchner Nielsen, N-P; Hug, F; Guével, A; Fohanno, V; Lardy, J; Dorel, S

    2016-12-20

    This study was designed to investigate how motor coordination adapts to unilateral fatigue of the quadriceps during a constant-load bilateral pedaling task. We first hypothesized that this local fatigue would not be compensated within the fatigued muscles leading to a decreased knee extension power. Then, we aimed to determine whether this decrease would be compensated by between-joints compensations within the ipsilateral leg and/or an increased contribution of the contralateral leg. Fifteen healthy volunteers were tested during pedaling at 350 W before and after a fatigue protocol consisting of 15 minutes of electromyostimulation on the quadriceps muscle. Motor coordination was assessed from myoelectrical activity (22 muscles) and joint powers calculated through inverse dynamics. Maximal knee extension torque decreased by 28.3%±6.8% (P<.0005) immediately after electromyostimulation. A decreased knee extension power produced by the ipsilateral leg was observed during pedaling (-22.8±12.3 W, -17.0%±9.4%; P<.0005). To maintain the task goal, participants primarily increased the power produced by the non-fatigued contralateral leg during the flexion phase. This was achieved by an increase in hip flexion power confirmed by a higher activation of the tensor fascia latae. These results suggest no adjustment of neural drive to the fatigued muscles and demonstrate no concurrent ipsilateral compensation by the non-fatigued muscles involved in the extension pedaling phase. Although interindividual variability was observed, findings provide evidence that participants predominantly adapted by compensating with the contralateral leg during its flexion phase. Both neural (between legs) and mechanical (between pedals) couplings and the minimization of cost functions might explain these results.

  15. Different functional reorganization of motor cortex after transfer of the contralateral C7 to different recipient nerves in young rats with total brachial plexus root avulsion.

    Science.gov (United States)

    Pan, Feng; Wei, Hai-feng; Chen, Liang; Gu, Yu-dong

    2012-12-07

    Clinically, contralateral C7 transfer is used for nerve reconstruction in brachial plexus injuries. Postoperatively, synchronous motions at the donor limb are noteworthy. This study studied if different recipient nerves influenced transhemispheric functional reorganization of motor cortex after this procedure. 90 young rats with total root avulsion of the brachial plexus were divided into groups 1-3 of contralateral C7 transfer to anterior division of the upper trunk, to both the musculocutaneous and median nerves, and to the median nerve, respectively. After reinnervation of target muscles, number of sites for forelimb representations in bilateral motor cortices was determined by intracortical microstimulation at 1.5, 3, 6, 9, and 12 months postoperatively. At nine months, transhemispheric reorganization of nerves neurotized by contralateral C7 was fulfilled in four of six rats in group 1, one of six in group 2 and none in group 3, respectively; at 12 months, that was fulfilled in five of six in group 1, four of six in groups 2 and 3, respectively. Logistic regression analysis showed that rate of fulfilled transhemispheric reorganization in group 1 was 12.19 times that in group 3 (95% CI 0.006-0.651, p=0.032). At 12 months, number of sites for hindlimb representations which had encroached upon original forelimb representations on the uninjured side was statistically more in group 3 than in group 2 (t=9.5, pnerves induces faster transhemispheric functional reorganization of motor cortex than that to median nerve alone in rats.

  16. Pathways and genes differentially expressed in the motor cortex of patients with sporadic amyotrophic lateral sclerosis

    Directory of Open Access Journals (Sweden)

    Santama Niovi

    2007-01-01

    Full Text Available Abstract Background Amyotrophic lateral sclerosis (ALS is a fatal disorder caused by the progressive degeneration of motoneurons in brain and spinal cord. Despite identification of disease-linked mutations, the diversity of processes involved and the ambiguity of their relative importance in ALS pathogenesis still represent a major impediment to disease models as a basis for effective therapies. Moreover, the human motor cortex, although critical to ALS pathology and physiologically altered in most forms of the disease, has not been screened systematically for therapeutic targets. Results By whole-genome expression profiling and stringent significance tests we identify genes and gene groups de-regulated in the motor cortex of patients with sporadic ALS, and interpret the role of individual candidate genes in a framework of differentially expressed pathways. Our findings emphasize the importance of defense responses and cytoskeletal, mitochondrial and proteasomal dysfunction, reflect reduced neuronal maintenance and vesicle trafficking, and implicate impaired ion homeostasis and glycolysis in ALS pathogenesis. Additionally, we compared our dataset with publicly available data for the SALS spinal cord, and show a high correlation of changes linked to the diseased state in the SALS motor cortex. In an analogous comparison with data for the Alzheimer's disease hippocampus we demonstrate a low correlation of global changes and a moderate correlation for changes specifically linked to the SALS diseased state. Conclusion Gene and sample numbers investigated allow pathway- and gene-based analyses by established error-correction methods, drawing a molecular portrait of the ALS motor cortex that faithfully represents many known disease features and uncovers several novel aspects of ALS pathology. Contrary to expectations for a tissue under oxidative stress, nuclear-encoded mitochondrial genes are uniformly down-regulated. Moreover, the down-regulation of

  17. Two whisker motor areas in the rat cortex: evidence from thalamocortical connections.

    Science.gov (United States)

    Mohammed, Hisham; Jain, Neeraj

    2014-02-15

    In primates, the motor cortex consists of at least seven different areas, which are involved in movement planning, coordination, initiation, and execution. However, for rats, only the primary motor cortex has been well described. A rostrally located second motor area has been proposed, but its extent, organization, and even definitive existence remain uncertain. Only a rostral forelimb area (RFA) has been definitively described, besides few reports of a rostral hindlimb area. We have previously proposed existence of a second whisker area, which we termed the rostral whisker area (RWA), based on its differential response to intracortical microstimulation compared with the caudal whisker area (CWA) in animals under deep anesthesia (Tandon et al. [2008] Eur J Neurosci 27:228). To establish that RWA is distinct from the caudally contiguous CWA, we determined sources of thalamic inputs to the two proposed whisker areas. Sources of inputs to RFA, caudal forelimb area (CFA), and caudal hindlimb region were determined for comparison. The results show that RWA and CWA can be distinguished based on differences in their thalamic inputs. RWA receives major projections from mediodorsal and ventromedial nuclei, whereas the major projections to CWA are from the ventral anterior, ventrolateral, and posterior nuclei. Moreover, the thalamic nuclei that provide major inputs to RWA are the same as for RFA, and the nuclei projecting to CWA are same as for CFA. The results suggest that rats have a second rostrally located motor area with RWA and RFA as its constituents. Copyright © 2013 Wiley Periodicals, Inc.

  18. Linear summation of outputs in a balanced network modelof motor cortex

    Directory of Open Access Journals (Sweden)

    Charles eCapaday

    2015-06-01

    Full Text Available Given the nonlinearities of the the neural circuitry's elements, we would expect corticalcircuits to respond nonlinearly when activated. Surprisingly, when two points in the motorcortex are activated simultaneously, the EMG responses are the linear sum of the responsesevoked by each of the points activated separately. Additionally, the corticospinal transferfunction is close to linear, implying that the synaptic interactions in motor cortex must beeffectively linear. To account for this, here we develop a model of motor cortex composedof multiple interconnected points, each comprised of reciprocally connected excitatory andinhibitory neurons. We show how nonlinearities in neuronal transfer functions areeschewed by strong synaptic interactions within each point. Consequently, thesimultaneous activation of multiple points results in a linear summation of their respectiveoutputs. We also consider the effects of reduction of inhibition at a cortical point when oneor more surrounding points are active. The network response in this condition is linear overan approximately two to three fold decrease of inhibitory feedback strength. This resultsupports the idea that focal disinhibition allows linear coupling of motor cortical points togenerate movement related muscle activation patterns; albeit with a limitation on gaincontrol. The model also explains why neural activity does not spread as far out as the axonalconnectivity allows, whilst also explaining why distant cortical points can be, nonetheless,functionally coupled by focal disinhibition. Finally, we discuss the advantages that linearinteractions at the cortical level afford to motor command synthesis.

  19. Mechanisms of human motor cortex facilitation induced by subthreshold 5-Hz repetitive transcranial magnetic stimulation.

    Science.gov (United States)

    Sommer, Martin; Rummel, Milena; Norden, Christoph; Rothkegel, Holger; Lang, Nicolas; Paulus, Walter

    2013-06-01

    Our knowledge about the mechanisms of human motor cortex facilitation induced by repetitive transcranial magnetic stimulation (rTMS) is still incomplete. Here we used pharmacological conditioning with carbamazepine, dextrometorphan, lorazepam, and placebo to elucidate the type of plasticity underlying this facilitation, and to probe if mechanisms reminiscent of long-term potentiation are involved. Over the primary motor cortex of 10 healthy subjects, we applied biphasic rTMS pulses of effective posterior current direction in the brain. We used six blocks of 200 pulses at 5-Hz frequency and 90% active motor threshold intensity and controlled for corticospinal excitability changes using motor-evoked potential (MEP) amplitudes and latencies elicited by suprathreshold pulses before, in between, and after rTMS. Target muscle was the dominant abductor digiti minimi muscle; we coregistered the dominant extensor carpi radialis muscle. We found a lasting facilitation induced by this type of rTMS. The GABAergic medication lorazepam and to a lesser extent the ion channel blocker carbamazepine reduced the MEP facilitation after biphasic effective posteriorly oriented rTMS, whereas the N-methyl-d-aspartate receptor-antagonist dextrometorphan had no effect. Our main conclusion is that the mechanism of the facilitation induced by biphasic effective posterior rTMS is more likely posttetanic potentiation than long-term potentiation. Additional findings were prolonged MEP latency under carbamazepine, consistent with sodium channel blockade, and larger MEP amplitudes from extensor carpi radialis under lorazepam, suggesting GABAergic involvement in the center-surround balance of excitability.

  20. Intrahemispheric dysfunction in primary motor cortex without corpus callosum: a transcranial magnetic stimulation study

    Directory of Open Access Journals (Sweden)

    Lassonde Maryse

    2006-06-01

    Full Text Available Abstract Background The two human cerebral hemispheres are continuously interacting, through excitatory and inhibitory influences and one critical structure subserving this interhemispheric balance is the corpus callosum. Interhemispheric neurophysiological abnormalities and intrahemispheric behavioral impairments have been reported in individuals lacking the corpus callosum. The aim of this study was to examine intrahemispheric neurophysiological function in primary motor cortex devoid of callosal projections. Methods Intracortical excitatory and inhibitory systems were tested in three individuals with complete agenesis of the corpus callosum and sixteen healthy individuals. These systems were assessed using transcranial magnetic stimulation (TMS protocols: motor threshold at rest, paired-pulse curve, and cortical silent period. Results TMS revealed no difference between the patient and control groups on the motor threshold measure, as well as intracortical facilitation and intracortical inhibition systems as tested by paired stimulation. However, intrahemispheric inhibitory function was found to be abnormal in participants without callosal projections, as the cortical silent period duration was significantly increased in the patient group. Conclusion These data suggest that in addition to previously reported impaired interhemispheric function, patients lacking the entire corpus callosum also display abnormal intrahemispheric excitability of the primary motor cortex.

  1. Increased occlusal vertical dimension induces cortical plasticity in the rat face primary motor cortex.

    Science.gov (United States)

    Kato, C; Fujita, K; Kokai, S; Ishida, T; Shibata, M; Naito, S; Yabushita, T; Ono, T

    2012-03-17

    Previous studies have demonstrated that functional plasticity in the primary motor cortex (M1) is related to motor-skill learning and changes in the environment. Increased occlusal vertical dimension (iOVD) may modulate mastication, such as in the masticatory cycle, and the firing properties of jaw-muscle spindles. However, little is known about the changes in motor representation within the face primary motor cortex (face-M1) after iOVD. The purpose of the present study was to determine the effect of iOVD on the face-M1 using intracortical microstimulation (ICMS). In an iOVD group, the maxillary molars were built-up by 2mm with acrylic. The electromyographic (EMG) activities from the left (LAD) and right (RAD) anterior digastric (AD), masseter and genioglossus (GG) muscles elicited by ICMS within the right face-M1 were recorded 1, 2 and 8 weeks after iOVD. IOVD was associated with a significant increase in the number of sites within the face-M1 from which ICMS evoked LAD and/or GG EMG activities, as well as a lateral shift in the center of gravity of the RAD and LAD muscles at 1 and 2 weeks, but not at 8 weeks. These findings suggest that a time-dependent neuroplastic change within the rat face-M1 occurs in association with iOVD. This may be related to the animal's ability to adapt to a change in the oral environment.

  2. Sensory-evoked and spontaneous gamma and spindle bursts in neonatal rat motor cortex.

    Science.gov (United States)

    An, Shuming; Kilb, Werner; Luhmann, Heiko J

    2014-08-13

    Self-generated neuronal activity originating from subcortical regions drives early spontaneous motor activity, which is a hallmark of the developing sensorimotor system. However, the neural activity patterns and role of primary motor cortex (M1) in these early movements are still unknown. Combining voltage-sensitive dye imaging (VSDI) with simultaneous extracellular multielectrode recordings in postnatal day 3 (P3)-P5 rat primary somatosensory cortex (S1) and M1 in vivo, we observed that tactile forepaw stimulation induced spindle bursts in S1 and gamma and spindle bursts in M1. Approximately 40% of the spontaneous gamma and spindle bursts in M1 were driven by early motor activity, whereas 23.7% of the M1 bursts triggered forepaw movements. Approximately 35% of the M1 bursts were uncorrelated to movements and these bursts had significantly fewer spikes and shorter burst duration. Focal electrical stimulation of layer V neurons in M1 mimicking physiologically relevant 40 Hz gamma or 10 Hz spindle burst activity reliably elicited forepaw movements. We conclude that M1 is already involved in somatosensory information processing during early development. M1 is mainly activated by tactile stimuli triggered by preceding spontaneous movements, which reach M1 via S1. Only a fraction of M1 activity transients trigger motor responses directly. We suggest that both spontaneously occurring and sensory-evoked gamma and spindle bursts in M1 contribute to the maturation of corticospinal and sensorimotor networks required for the refinement of sensorimotor coordination.

  3. A Causal Role for Primary Motor Cortex in Perception of Observed Actions

    Science.gov (United States)

    Palmer, Clare E.; Bunday, Karen L.; Davare, Marco; Kilner, James M.

    2017-01-01

    It has been proposed that motor system activity during action observation may be modulated by the kinematics of observed actions. One purpose of this activity during action observation may be to predict the visual consequence of another person’s action based on their movement kinematics. Here, we tested the hypothesis that the primary motor cortex (M1) may have a causal role in inferring information that is present in the kinematics of observed actions. Healthy participants completed an action perception task before and after applying continuous theta burst stimulation (cTBS) over left M1. A neurophysiological marker was used to quantify the extent of M1 disruption following cTBS and stratify our sample a priori to provide an internal control. We found that a disruption to M1 caused a reduction in an individual’s sensitivity to interpret the kinematics of observed actions; the magnitude of suppression of motor excitability predicted this change in sensitivity. PMID:27458752

  4. The Effect of Aerobic Exercise on Neuroplasticity within the Motor Cortex following Stroke.

    Directory of Open Access Journals (Sweden)

    Kate Murdoch

    Full Text Available Aerobic exercise is associated with enhanced plasticity in the motor cortex of healthy individuals, but the effect of aerobic exercise on neuroplasticity following a stroke is unknown.The aim of this study was to compare corticomotoneuronal excitability and neuroplasticity in the upper limb cortical representation following a single session of low intensity lower limb cycling, or a rest control condition.We recruited chronic stroke survivors to take part in three experimental conditions in a randomised, cross-over design. Corticomotoneuronal excitability was examined using transcranial magnetic stimulation to elicit motor evoked potentials in the affected first dorsal interosseus muscle. Following baseline measures, participants either cycled on a stationary bike at a low exercise intensity for 30 minutes, or remained resting in a seated position for 30 minutes. Neuroplasticity within the motor cortex was then examined using an intermittent theta burst stimulation (iTBS paradigm. During the third experimental condition, participants cycled for the 30 minutes but did not receive any iTBS.Twelve participants completed the study. We found no significant effect of aerobic exercise on corticomotoneuronal excitability when compared to the no exercise condition (P > 0.05 for all group and time comparisons. The use of iTBS did not induce a neuroplastic-like response in the motor cortex with or without the addition of aerobic exercise.Our results suggest that following a stroke, the brain may be less responsive to non-invasive brain stimulation paradigms that aim to induce short-term reorganisation, and aerobic exercise was unable to induce or improve this response.

  5. Response to Niklasson's comment on Lin, et al. (2012) : "the relation between postural movement and bilateral motor integration".

    Science.gov (United States)

    Lin, Chin-Kai; Kuo, Bor-Chen; Wu, Huey-Min

    2014-10-01

    In the study of Lin, Wu, Lin, Wu, Wu, Kuo, and Yeung (2012 ), the relationship between the validity of postural movement and bilateral motor integration in terms of sensory integration theory was examined. Postural movement is the ability to use the antigravity postures required for stabilization of the neck, trunk and upper extremities via muscle co-contractions in the neck and upper extremities, and balance. Niklasson's (2013 ) comment argued that postural movement should include primitive reflexes in terms of the general abilities approach. Niklasson (2013 ) focused on the efficacy of the treatment rather than the theoretical frameworks implied in the therapeutic activities. For that purpose Lin, et al. (2012 ) used sensory integration as the theoretical foundation, and the relationship between postural movement and bilateral motor integration was assessed via empirical data. The result of Lin, et al. (2012 ) was offered as a theoretical reference for therapeutic activities.

  6. Histological-MRI correlation in the primary motor cortex of patients with amyotrophic lateral sclerosis.

    Science.gov (United States)

    Meadowcroft, Mark D; Mutic, Nathan J; Bigler, Don C; Wang, Jian-Li; Simmons, Zachary; Connor, James R; Yang, Qing X

    2015-03-01

    To establish the relationship between ALS histopathology and quantitative MRI metrics. ALS patients (N = 8) in advanced stages of the disease were enrolled and, immediately after death, the brain of each patient was removed. Freshly excised ALS tissue was imaged at 3.0 Tesla with T1 and T2 mapping protocols and subsequently stained with astrocyte, myelin, and neuronal markers. Measures of ALS histological stains were compared with the internal control (primary visual cortex) and longitudinal parametric maps. Post-mortem T1 -weighted images demonstrate diminished contrast between gray and white matter and alterations in T1 relaxation within the primary motor cortex. An increase in astrocyte number and reactivity as well as evident neuronal loss, a decrease in axonal density, and unraveling of the myelin sheaths in subcortical white matter were found in the ALS primary motor cortex exhibiting significant T1 relaxation and contrast changes. This study provides a histopathological basis for differences in MR T1 contrast and relaxation seen in the ALS brain. © 2014 Wiley Periodicals, Inc.

  7. Low Doses of Ethanol Enhance LTD-like Plasticity in Human Motor Cortex.

    Science.gov (United States)

    Fuhl, Anna; Müller-Dahlhaus, Florian; Lücke, Caroline; Toennes, Stefan W; Ziemann, Ulf

    2015-12-01

    Humans liberally use ethanol for its facilitating effects on social interactions but its effects on central nervous system function remain underexplored. We have recently described that very low doses of ethanol abolish long-term potentiation (LTP)-like plasticity in human cortex, most likely through enhancement of tonic inhibition [Lücke et al, 2014, Neuropsychopharmacology 39:1508-18]. Here, we studied the effects of low-dose ethanol on long-term depression (LTD)-like plasticity. LTD-like plasticity was induced in human motor cortex by paired associative transcranial magnetic stimulation (PASLTD), and measured as decreases of motor evoked potential input-output curve (IO-curve). In addition, sedation was measured by decreases in saccade peak velocity (SPV). Ethanol in two low doses (EtOHethanol, easily reached during social drinking, enhance LTD-like plasticity in human cortex. This effect is most likely explained by the activation of extrasynaptic α4-subunit containing gamma-aminobutyric type A receptors by low-dose EtOH, resulting in increased tonic inhibition. Findings may stimulate cellular research on the role of tonic inhibition in regulating excitability and plasticity of cortical neuronal networks.

  8. 5 Hz repetitive transcranial magnetic stimulation over the ipsilesional sensory cortex enhances motor learning after stroke

    Directory of Open Access Journals (Sweden)

    Sonia M Brodie

    2014-03-01

    Full Text Available Sensory feedback is critical for motor learning, and thus to neurorehabilitation after stroke. Whether enhancing sensory feedback by applying excitatory repetitive transcranial magnetic stimulation (rTMS over the ipsilesional primary sensory cortex (IL-S1 might enhance motor learning in chronic stroke has yet to be investigated. The present study investigated the effects of 5 Hz rTMS over IL-S1 paired with skilled motor practice on motor learning, hemiparetic cutaneous somatosensation, and motor function. Individuals with unilateral chronic stroke were pseudo-randomly divided into either Active or Sham 5 Hz rTMS groups (n=11/group. Following stimulation, both groups practiced a Serial Tracking Task (STT with the hemiparetic arm; this was repeated for 5 days. Performance on the STT was quantified by response time, peak velocity, and cumulative distance tracked at baseline, during the 5 days of practice, and at a no-rTMS retention test. Cutaneous somatosensation was measured using two-point discrimination. Standardized sensorimotor tests were performed to assess whether the effects might generalize to impact hemiparetic arm function. The active 5Hz rTMS + training group demonstrated significantly greater improvements in STT performance [response time (F1,286.04=13.016, p< 0.0005, peak velocity (F1,285.95=4.111, p=0.044, and cumulative distance (F1,285.92=4.076, p=0.044] and cutaneous somatosensation (F1,21.15=8.793, p=0.007 across all sessions compared to the sham rTMS + training group. Measures of upper extremity motor function were not significantly different for either group. Our preliminary results suggest that, when paired with motor practice, 5Hz rTMS over IL-S1 enhances motor learning related change in individuals with chronic stroke, potentially as a consequence of improved cutaneous somatosensation, however no improvement in general upper extremity function was observed.

  9. Motor Cortex Excitability and BDNF Levels in Chronic Musculoskeletal Pain According to Structural Pathology.

    Science.gov (United States)

    Caumo, Wolnei; Deitos, Alícia; Carvalho, Sandra; Leite, Jorge; Carvalho, Fabiana; Dussán-Sarria, Jairo Alberto; Lopes Tarragó, Maria da Graça; Souza, Andressa; Torres, Iraci Lucena da Silva; Fregni, Felipe

    2016-01-01

    The central sensitization syndrome (CSS) encompasses disorders with overlapping symptoms in a structural pathology spectrum ranging from persistent nociception [e.g., osteoarthritis (OA)] to an absence of tissue injuries such as the one presented in fibromyalgia (FM) and myofascial pain syndrome (MPS). First, we hypothesized that these syndromes present differences in their cortical excitability parameters assessed by transcranial magnetic stimulation (TMS), namely motor evoked potential (MEP), cortical silent period (CSP), short intracortical inhibition (SICI) and short intracortical facilitation (SICF). Second, considering that the presence of tissue injury could be detected by serum neurotrophins, we hypothesized that the spectrum of structural pathology (i.e., from persistent nociception like in OA, to the absence of tissue injury like in FM and MPS), could be detected by differential efficiency of their descending pain inhibitory system, as assessed by the conditioned pain modulation (CPM) paradigm. Third, we explored whether brain-derived neurotrophic factor (BDNF) had an influence on the relationship between motor cortex excitability and structural pathology. This cross-sectional study pooled baseline data from three randomized clinical trials. We included females (n = 114), aged 19-65 years old with disability by chronic pain syndromes (CPS): FM (n = 19), MPS (n = 54), OA (n = 27) and healthy subjects (n = 14). We assessed the serum BDNF, the motor cortex excitability by parameters the TMS measures and the change on numerical pain scale [NPS (0-10)] during CPM-task. The adjusted mean (SD) on the SICI observed in the absence of tissue injury was 56.36% lower than with persistent nociceptive input [0.31(0.18) vs. 0.55 (0.32)], respectively. The BDNF was inversely correlated with the SICI and with the change on NPS (0-10)during CPM-task. These findings suggest greater disinhibition in the motor cortex and the descending pain inhibitory system in FM and MPS

  10. Motor Cortex Excitability and BDNF Levels in Chronic Musculoskeletal Pain According to Structural Pathology

    Science.gov (United States)

    Caumo, Wolnei; Deitos, Alícia; Carvalho, Sandra; Leite, Jorge; Carvalho, Fabiana; Dussán-Sarria, Jairo Alberto; Lopes Tarragó, Maria da Graça; Souza, Andressa; Torres, Iraci Lucena da Silva; Fregni, Felipe

    2016-01-01

    The central sensitization syndrome (CSS) encompasses disorders with overlapping symptoms in a structural pathology spectrum ranging from persistent nociception [e.g., osteoarthritis (OA)] to an absence of tissue injuries such as the one presented in fibromyalgia (FM) and myofascial pain syndrome (MPS). First, we hypothesized that these syndromes present differences in their cortical excitability parameters assessed by transcranial magnetic stimulation (TMS), namely motor evoked potential (MEP), cortical silent period (CSP), short intracortical inhibition (SICI) and short intracortical facilitation (SICF). Second, considering that the presence of tissue injury could be detected by serum neurotrophins, we hypothesized that the spectrum of structural pathology (i.e., from persistent nociception like in OA, to the absence of tissue injury like in FM and MPS), could be detected by differential efficiency of their descending pain inhibitory system, as assessed by the conditioned pain modulation (CPM) paradigm. Third, we explored whether brain-derived neurotrophic factor (BDNF) had an influence on the relationship between motor cortex excitability and structural pathology. This cross-sectional study pooled baseline data from three randomized clinical trials. We included females (n = 114), aged 19–65 years old with disability by chronic pain syndromes (CPS): FM (n = 19), MPS (n = 54), OA (n = 27) and healthy subjects (n = 14). We assessed the serum BDNF, the motor cortex excitability by parameters the TMS measures and the change on numerical pain scale [NPS (0–10)] during CPM-task. The adjusted mean (SD) on the SICI observed in the absence of tissue injury was 56.36% lower than with persistent nociceptive input [0.31(0.18) vs. 0.55 (0.32)], respectively. The BDNF was inversely correlated with the SICI and with the change on NPS (0–10)during CPM-task. These findings suggest greater disinhibition in the motor cortex and the descending pain inhibitory system in FM and

  11. Motor cortex excitability and BDNF levels in chronic musculoskeletal pain according to structural pathology

    Directory of Open Access Journals (Sweden)

    Alícia Deitos

    2016-07-01

    Full Text Available The central sensitization syndrome (CSS encompasses disorders with overlapping symptoms in a structural pathology spectrum ranging from persistent nociception [e.g., osteoarthritis (OA] to an absence of tissue injuries such as the one presented in fibromyalgia (FM and myofascial pain syndrome (MPS. First, we hypothesized that these syndromes present differences in their cortical excitability parameters assessed by TMS, namely motor evoked potential (MEP, cortical silent period (CSP, short intracortical inhibition (SICI and short intracortical facilitation (SICF. Second, considering that the presence of tissue injury could be detected by serum neurotrophins, we hypothesized that the spectrum of structural pathology (i.e., from persistent nociception like in OA, to the absence of tissue injury like in FM and MPS, could be detected by differential efficiency of their descending pain inhibitory system, as assessed by the conditioned pain modulation (CPM paradigm. Third, we explored whether BDNF had an influence on the relationship between motor cortex excitability and structural pathology. This cross-sectional study pooled baseline data from three randomized clinical trials. We included females (n=114, aged 19 to 65 years old with disability by chronic pain syndromes: FM (n= 19, MPS (n=54, OA (n=27 and healthy subjects (n=14. We assessed the serum BDNF, the motor cortex excitability by parameters the TMS measures and the change on Numerical Pain Scale [NPS (0-10] during CPM-task. The adjusted mean (SD on the SICI observed in the absence of tissue injury was 56.36% lower than with persistent nociceptive input [0.31(0.18 vs. 0.55 (0.32], respectively. The BDNF was inversely correlated with the SICI and with the change on NPS (0-10 during CPM-task. These findings suggest greater disinhibition in the motor cortex and the descending pain inhibitory system in FM and MPS than in OA and healthy subjects. Likewise, the inter-hemispheric disinhibition as well

  12. Motor adaptations to local muscle pain during a bilateral cyclic task.

    Science.gov (United States)

    Brøchner Nielsen, Niels-Peter; Tucker, Kylie; Dorel, Sylvain; Guével, Arnaud; Hug, François

    2017-02-01

    The aim of this study was to determine how unilateral pain, induced in two knee extensor muscles, affects muscle coordination during a bilateral pedaling task. Fifteen participants performed a 4-min pedaling task at 130 W in two conditions (Baseline and Pain). Pain was induced by injection of hypertonic saline into the vastus medialis (VM) and vastus lateralis (VL) muscles of one leg. Force applied throughout the pedaling cycle was measured using an instrumented pedal and used to calculate pedal power. Surface electromyography (EMG) was recorded bilaterally from eight muscles to assess changes in muscle activation strategies. Compared to Baseline, during the Pain condition, EMG amplitude of muscles of the painful leg (VL and VM-the painful muscles, and RF-another quadriceps muscle with no pain) was lower during the extension phase [(mean ± SD): VL: -22.5 ± 18.9%; P < 0.001; VM: -28.8 ± 19.9%; P < 0.001, RF: -20.2 ± 13.9%; P < 0.001]. Consistent with this, pedal power applied by the painful leg was also lower during the extension phase (-16.8 ± 14.2 W, P = 0.001) during Pain compared to Baseline. This decrease was compensated for by an 11.3 ± 8.1 W increase in pedal power applied by the non-painful leg during its extension phase (P = 0.04). These results support pain adaptation theories, which suggest that when there is a clear opportunity to compensate, motor adaptations to pain occur to decrease load within the painful tissue. Although the pedaling task offered numerous possibilities for compensation, only between-leg compensations were systematically observed. This finding is discussed in relation to the mechanical and neural constraints of the pedaling task.

  13. Learning-Dependent Potentiation in the Vibrissal Motor Cortex Is Closely Related to the Acquisition of Conditioned Whisker Responses in Behaving Mice

    Science.gov (United States)

    Delgado-Garcia, Jose Maria; Troncoso, Julieta; Munera, Alejandro

    2007-01-01

    The role of the primary motor cortex in the acquisition of new motor skills was evaluated during classical conditioning of vibrissal protraction responses in behaving mice, using a trace paradigm. Conditioned stimulus (CS) presentation elicited a characteristic field potential in the vibrissal motor cortex, which was dependent on the synchronized…

  14. Learning-Dependent Potentiation in the Vibrissal Motor Cortex Is Closely Related to the Acquisition of Conditioned Whisker Responses in Behaving Mice

    Science.gov (United States)

    Delgado-Garcia, Jose Maria; Troncoso, Julieta; Munera, Alejandro

    2007-01-01

    The role of the primary motor cortex in the acquisition of new motor skills was evaluated during classical conditioning of vibrissal protraction responses in behaving mice, using a trace paradigm. Conditioned stimulus (CS) presentation elicited a characteristic field potential in the vibrissal motor cortex, which was dependent on the synchronized…

  15. Inference and Decoding of Motor Cortex Low-Dimensional Dynamics via Latent State-Space Models.

    Science.gov (United States)

    Aghagolzadeh, Mehdi; Truccolo, Wilson

    2016-02-01

    Motor cortex neuronal ensemble spiking activity exhibits strong low-dimensional collective dynamics (i.e., coordinated modes of activity) during behavior. Here, we demonstrate that these low-dimensional dynamics, revealed by unsupervised latent state-space models, can provide as accurate or better reconstruction of movement kinematics as direct decoding from the entire recorded ensemble. Ensembles of single neurons were recorded with triple microelectrode arrays (MEAs) implanted in ventral and dorsal premotor (PMv, PMd) and primary motor (M1) cortices while nonhuman primates performed 3-D reach-to-grasp actions. Low-dimensional dynamics were estimated via various types of latent state-space models including, for example, Poisson linear dynamic system (PLDS) models. Decoding from low-dimensional dynamics was implemented via point process and Kalman filters coupled in series. We also examined decoding based on a predictive subsampling of the recorded population. In this case, a supervised greedy procedure selected neuronal subsets that optimized decoding performance. When comparing decoding based on predictive subsampling and latent state-space models, the size of the neuronal subset was set to the same number of latent state dimensions. Overall, our findings suggest that information about naturalistic reach kinematics present in the recorded population is preserved in the inferred low-dimensional motor cortex dynamics. Furthermore, decoding based on unsupervised PLDS models may also outperform previous approaches based on direct decoding from the recorded population or on predictive subsampling.

  16. Magnetic susceptibility in the deep layers of the primary motor cortex in Amyotrophic Lateral Sclerosis

    Directory of Open Access Journals (Sweden)

    M. Costagli

    2016-01-01

    Full Text Available Amyotrophic Lateral Sclerosis (ALS is a progressive neurological disorder that entails degeneration of both upper and lower motor neurons. The primary motor cortex (M1 in patients with upper motor neuron (UMN impairment is pronouncedly hypointense in Magnetic Resonance (MR T2* contrast. In the present study, 3D gradient-recalled multi-echo sequences were used on a 7 Tesla MR system to acquire T2*-weighted images targeting M1 at high spatial resolution. MR raw data were used for Quantitative Susceptibility Mapping (QSM. Measures of magnetic susceptibility correlated with the expected concentration of non-heme iron in different regions of the cerebral cortex in healthy subjects. In ALS patients, significant increases in magnetic susceptibility co-localized with the T2* hypointensity observed in the middle and deep layers of M1. The magnetic susceptibility, hence iron concentration, of the deep cortical layers of patients' M1 subregions corresponding to Penfield's areas of the hand and foot in both hemispheres significantly correlated with the clinical scores of UMN impairment of the corresponding limbs. QSM therefore reflects the presence of iron deposits related to neuroinflammatory reaction and cortical microgliosis, and might prove useful in estimating M1 iron concentration, as a possible radiological sign of severe UMN burden in ALS patients.

  17. Magnetic susceptibility in the deep layers of the primary motor cortex in Amyotrophic Lateral Sclerosis.

    Science.gov (United States)

    Costagli, M; Donatelli, G; Biagi, L; Caldarazzo Ienco, E; Siciliano, G; Tosetti, M; Cosottini, M

    2016-01-01

    Amyotrophic Lateral Sclerosis (ALS) is a progressive neurological disorder that entails degeneration of both upper and lower motor neurons. The primary motor cortex (M1) in patients with upper motor neuron (UMN) impairment is pronouncedly hypointense in Magnetic Resonance (MR) T2* contrast. In the present study, 3D gradient-recalled multi-echo sequences were used on a 7 Tesla MR system to acquire T2*-weighted images targeting M1 at high spatial resolution. MR raw data were used for Quantitative Susceptibility Mapping (QSM). Measures of magnetic susceptibility correlated with the expected concentration of non-heme iron in different regions of the cerebral cortex in healthy subjects. In ALS patients, significant increases in magnetic susceptibility co-localized with the T2* hypointensity observed in the middle and deep layers of M1. The magnetic susceptibility, hence iron concentration, of the deep cortical layers of patients' M1 subregions corresponding to Penfield's areas of the hand and foot in both hemispheres significantly correlated with the clinical scores of UMN impairment of the corresponding limbs. QSM therefore reflects the presence of iron deposits related to neuroinflammatory reaction and cortical microgliosis, and might prove useful in estimating M1 iron concentration, as a possible radiological sign of severe UMN burden in ALS patients.

  18. Functional mapping of the sensorimotor cortex: combined use of magnetoencephalography, functional MRI, and motor evoked potentials

    Energy Technology Data Exchange (ETDEWEB)

    Morioka, T. [Dept. of Neurosurgery, Neurological Inst., Kyshu Univ., Fukuoka (Japan); Fujii, K. [Dept. of Neurosurgery, Neurological Inst., Kyshu Univ., Fukuoka (Japan); Fukui, M. [Dept. of Neurosurgery, Neurological Inst., Kyshu Univ., Fukuoka (Japan); Mizushima, A. [Dept. of Radiology, Kyushu Univ. Fukuoka (Japan); Matsumoto, S. [Dept. of Radiology, Kyushu Univ. Fukuoka (Japan); Hasuo, K. [Dept. of Radiology, Kyushu Univ. Fukuoka (Japan); Yamamoto, T. [Dept. of Otolaryngology, Kyushu Univ. Fukuoka (Japan); Tobimatsu, S. [Dept. of Clinical Neurophysiology, Neurological Inst., Kyushu Univ., Fukuoka (Japan)

    1995-10-01

    Combined use of magnetoencephalography (MEG), functional magnetic resonance imaging (f-MRI), and motor evoked potentials (MEPs) was carried out on one patient in an attempt to localise precisely a structural lesion to the central sulcus. A small cyst in the right frontoparietal region was thought to be the cause of generalised seizures in an otherwise asymptomatic woman. First the primary sensory cortex was identified with magnetic source imaging (MSI) of somatosensory evoked magnetic fields using MEG and MRI. Second, the motor area of the hand was identified using f-MRI during handsqueezing. Then transcranial magnetic stimulation localised the hand motor area on the scalp, which was mapped onto the MRI. There was a good agreement between MSI, f-MRI and MEP as to the location of the sensorimotor cortex and its relationship to the lesion. Multimodality mapping techniques may thus prove useful in the precise localisation of cortical lesions, and in the preoperative determination of the best treatment for peri-rolandic lesions. (orig.)

  19. Stimulus-response profile during single-pulse transcranial magnetic stimulation to the primary motor cortex.

    Science.gov (United States)

    Hanakawa, Takashi; Mima, Tatsuya; Matsumoto, Riki; Abe, Mitsunari; Inouchi, Morito; Urayama, Shin-Ichi; Anami, Kimitaka; Honda, Manabu; Fukuyama, Hidenao

    2009-11-01

    We examined the stimulus-response profile during single-pulse transcranial magnetic stimulation (TMS) by measuring motor-evoked potentials (MEPs) with electromyographic monitoring and hemodynamic responses with functional magnetic resonance imaging (fMRI) at 3 Tesla. In 16 healthy subjects, single TMS pulses were irregularly delivered to the left primary motor cortex at a mean frequency of 0.15 Hz with a wide range of stimulus intensities. The measurement of MEP proved a typical relationship between stimulus intensity and MEP amplitude in the concurrent TMS-fMRI environment. In the population-level analysis of the suprathreshold stimulation conditions, significant increases in hemodynamic responses were detected in the motor/somatosensory network, reflecting both direct and remote effects of TMS, and also the auditory/cognitive areas, perhaps related to detection of clicks. The stimulus-response profile showed both linear and nonlinear components in the direct and remote motor/somatosensory network. A detailed analysis suggested that the nonlinear components of the motor/somatosensory network activity might be induced by nonlinear recruitment of neurons in addition to sensory afferents resulting from movement. These findings expand our basic knowledge of the quantitative relationship between TMS-induced neural activations and hemodynamic signals measured by neuroimaging techniques.

  20. Recurrent CSPs after Transcranial Magnetic Stimulation of Motor Cortex in Restless Legs Syndrome

    Directory of Open Access Journals (Sweden)

    Aulikki Ahlgrén-Rimpiläinen

    2012-01-01

    Full Text Available Aims. The aim of this study was to investigate the motor control and central silent period (CSP in restless legs syndrome (RLS. Methods. Transcranial magnetic stimulation was focused on the dominant and nondominant hemispheric areas of motor cortex in six subjects with RLS and six controls. The responses were recorded on the contralateral abductor digiti minimi (ADM and tibialis anterior (TA muscles with intramuscular needle electrodes. Results. No significant differences were found in the motor conduction or central motor conduction time, in the latency, or in the duration of the CSPs between or within the groups, but multiple CSPs were observed in both groups. The number of the CSPs was significantly higher in both ADMs and in the dominant TA (P≤0.01 in the RLS group compared to the controls. Conclusion. Descending motor pathways functioned correctly in both groups. The occurrence of the recurrent CSPs predominantly in the RLS group could be a sign of a change of function in the inhibitory control system. Further research is needed to clarify the role of the intramuscular recording technique and especially the role of the subcortical generators in the feedback regulation of the central nervous system in RLS.

  1. Reduced excitability of the motor cortex in untreated patients with de novo idiopathic "grand mal" seizures.

    Science.gov (United States)

    Delvaux, V; Alagona, G; Gérard, P; De Pasqua, V; Delwaide, P J; Maertens de Noordhout, A

    2001-12-01

    Transcranial magnetic stimulation (TMS) was used to investigate motor cortex excitability, intracortical excitatory, and inhibitory pathways in 18 patients having experienced a first "grand mal" seizure within 48 hours of the electrophysiological test. All had normal brain MRI, and were free of any treatment, drug, or alcohol misuse. Results were compared with those of 35 age matched normal volunteers. The following parameters of responses to TMS were measured: motor thresholds at rest and with voluntary contraction, amplitudes of responses, cortical silent periods, and responses to paired pulse stimulation with interstimulus intervals of 1 to 20 ms. In patients, there were significantly increased motor thresholds with normal amplitudes of motor evoked potentials (MEPs), suggesting decreased cortical excitability. Cortical silent periods were not significantly different from those of normal subjects. Paired TMS with short interstimulus intervals (1-5 ms) induced normal inhibition of test MEPs, suggesting preserved function of GABAergic intracortical inhibitory interneurons. On the contrary, the subsequent period of MEP facilitation found in normal subjects (ISIs of 6-20 ms) was markedly reduced in patients. This suggests the existence of abnormally prolonged intracortical inhibition or deficient intracortical excitation. In nine patients retested 2 to 4 weeks after the initial seizure, these abnormalities persisted, although to a lesser extent. The present findings together with abnormally high motor thresholds could represent protective mechanisms against the spread or recurrence of seizures.

  2. Structural and functional definition of the motor cortex in the monkey (Macaca fascicularis).

    Science.gov (United States)

    Sessle, B J; Wiesendanger, M

    1982-02-01

    1. The details of the organization of the motor cortex and its anterior and posterior border were investigated in three monkeys by a combination of techniques including intracortical microstimulation (i.c.m.s.), electrophysiological recording of cutaneous and muscle afferent inputs to single cortical neurones, and electrophysiological and anatomical identification of corticospinal neurones; in addition, data from these methods were related to cortical cytoarchitecture.2. Almost 5000 individual cortical loci were tested with i.c.m.s. in the unanaesthetized monkeys. In this paper, we particularly consider the organization of the forelimb motor representation, and its relation to the representation of other parts of the body. I.c.m.s. thresholds of about 5 muA were common for evoking twitch movements and e.m.g. responses in distal forelimb and face, jaw and tongue muscles, but proximal forelimb, trunk and hind-limb movements also sometimes had such low thresholds.3. The fingers were found to be represented nearest the central sulcus, with horseshoe-shaped bands of cortical tissue representing progressively more proximal muscles situated around this central ;finger core'.4. Cytoarchitectonically, the cortex having these low-threshold motor effects was characteristic of area 4. There was also a close fit between the extent of this ;excitable cortex' and the extent of densely spaced corticospinal neurones identified electro-physiologically or with horseradish peroxidase labelling. In subsequent mapping of forelimb afferents to the cortex when the animal was deeply anaesthetized, low-threshold and short-latency responses to muscle nerve stimulation were rarely found in this ;excitable cortex'.5. The anterior border could be clearly established by i.c.m.s. and by the sharp boundary of corticospinal neurones. It was noted that the motor cortex extends rostrally beyond area 4 and its anterior border appears to reside in the posterior part of area 6aalpha (Vogt & Vogt, 1919

  3. Primary Motor Cortex Excitability in Karate Athletes: A Transcranial Magnetic Stimulation Study

    Directory of Open Access Journals (Sweden)

    Vincenzo Monda

    2017-09-01

    Full Text Available Purpose: The mechanisms involved in the coordination of muscle activity are not completely known: to investigate adaptive changes in human motor cortex Transcranial magnetic stimulation (TMS was often used. The sport models are frequently used to study how the training may affect the corticospinal system excitability: Karate represents a valuable sport model for this kind of investigations for its high levels of coordination required to athletes. This study was aimed at examining possible changes in the resting motor threshold (rMT and in the corticospinal response in karate athletes, and at determining whether athletes are characterized by a specific value of rMT.Methods: We recruited 25 right-handed young karate athletes and 25 matched non-athletes. TMS was applied to primary motor cortex (M1. Motor evoked potential (MEP were recorded by two electrodes placed above the first dorsal interosseous (FDI muscle. We considered MEP latencies and amplitudes at rMT, 110% of rMT, and 120% of rMT.Results: The two groups were similar for age (p > 0.05, height (p > 0.05 and body mass (p > 0.05. The TMS had a 70-mm figure-of-eight coil and a maximum output of 2.2 T, placed over the left motor cortex. During the stimulation, a mechanical arm kept the coil tangential to the scalp, with the handle at 45° respect to the midline. The SofTaxic navigator system (E.M.S. Italy, www.emsmedical.net was used in order to correctly identifying and repeating the stimulation for every subject. Compared to non-athletes, athletes showed a lower resting motor threshold (p < 0.001. Furthermore, athletes had a lower MEP latency (p < 0.001 and a higher MEP amplitude (p < 0.001 compared to non-athletes. Moreover, a ROC curve for rMT was found significant (area: 0.907; sensitivity 84%, specificity 76%.Conclusions: As the main finding, the present study showed significant differences in cortical excitability between athletes and non-athletes. The training can improve cortical

  4. Plasticity in bilateral superior temporal cortex: Effects of deafness and cochlear implantation on auditory and visual speech processing.

    Science.gov (United States)

    Anderson, Carly A; Lazard, Diane S; Hartley, Douglas E H

    2017-01-01

    While many individuals can benefit substantially from cochlear implantation, the ability to perceive and understand auditory speech with a cochlear implant (CI) remains highly variable amongst adult recipients. Importantly, auditory performance with a CI cannot be reliably predicted based solely on routinely obtained information regarding clinical characteristics of the CI candidate. This review argues that central factors, notably cortical function and plasticity, should also be considered as important contributors to the observed individual variability in CI outcome. Superior temporal cortex (STC), including auditory association areas, plays a crucial role in the processing of auditory and visual speech information. The current review considers evidence of cortical plasticity within bilateral STC, and how these effects may explain variability in CI outcome. Furthermore, evidence of audio-visual interactions in temporal and occipital cortices is examined, and relation to CI outcome is discussed. To date, longitudinal examination of changes in cortical function and plasticity over the period of rehabilitation with a CI has been restricted by methodological challenges. The application of functional near-infrared spectroscopy (fNIRS) in studying cortical function in CI users is becoming increasingly recognised as a potential solution to these problems. Here we suggest that fNIRS offers a powerful neuroimaging tool to elucidate the relationship between audio-visual interactions, cortical plasticity during deafness and following cochlear implantation, and individual variability in auditory performance with a CI. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  5. [The functional role of the motor area of the cortex in the acquisition of escape reactions in dogs].

    Science.gov (United States)

    Frolov, A G; Maslov, A V; Pavlova, O G

    1993-01-01

    The model of escape conditioning similar to classical (pavlovian) was proposed. During shock application to the hind limb (a conditioned stimulus) the ipsilateral foreleg flexion was elicited by a stimulation of the motor cortex (an unconditioned stimulus); both stimuli were turned off in the course of the forepaw lifting. Such uniform pairings resulted in elaboration of a reaction of the foreleg flexion in response to the shock. Prolonging the shock by 3 s after the cortical stimulation led to a rapid extinction of the acquired response. So a possibility to instrumentalize movements elicited by stimulation of the motor cortex (MI) was proved. This is in argument in favour of an assumption that the established "instrumental" connection (drive-motor structures) can be addressed directly to the motor cortex.

  6. Stimulation of the human motor cortex alters generalization patterns of motor learning

    OpenAIRE

    Orban de Xivry, Jean-Jacques; Marko, Mollie K; Pekny, Sarah E.; Pastor, Damien; Izawa, Jun; Celnik, Pablo; Shadmehr, Reza

    2011-01-01

    It has been hypothesized that the generalization patterns that accompany learning carry the signatures of the neural systems that are engaged in that learning. Reach adaptation in force fields has generalization patterns that suggest primary engagement of a neural system that encodes movements in the intrinsic coordinates of joints and muscles, and lesser engagement of a neural system that encodes movements in the extrinsic coordinates of the task. Among the cortical motor areas, the intrinsi...

  7. Dose-response curve of associative plasticity in human motor cortex and interactions with motor practice.

    Science.gov (United States)

    Elahi, Behzad; Hutchison, William D; Daskalakis, Z Jeff; Gunraj, Carolyn; Chen, Robert

    2014-02-01

    Associative plasticity is hypothesized to be an important neurophysiological correlate of memory formation and learning with potentials for applications in neurorehabilitation and for the development of new electrophysiological measures to study disorders of cortical plasticity. We hypothesized that the magnitude of the paired associative stimulation (PAS)-induced long-term potentiation (LTP)-like effect depends on the number of pairs in the PAS protocol. We also hypothesized that homeostatic interaction of PAS with subsequent motor learning is related to the magnitude of the PAS-induced LTP-like effect. We studied 10 healthy subjects. In experiment 1a, subjects received 90 (PAS90), 180 (PAS180), or 270 (PAS270) pairs of stimuli, followed by a dynamic motor practice (DMP) 1 h after the end of the PAS protocols. In experiment 1b, the DMP preceded the PAS protocol. In experiment 2, the time course of PAS270 was studied. We found that PAS270 resulted in greater increase in motor evoked potential (MEP) amplitude compared with protocols with fewer pairs of stimuli. Moreover, the interaction between PAS protocols with motor learning differed depending on the number of stimulus pairs used to induce PAS. While DMP alone increased MEP amplitudes, DMP during the LTP-like effects induced by PAS270 led to a long-term depression (LTD)-like effect (homeostatic interaction). This homeostatic interaction did not occur after PAS90 and PAS180. In conclusion, we found a dose-dependent effect of the number of stimulus pairs used in the PAS protocol on cortical plasticity. Homeostatic interaction between PAS and DMP was observed only after PAS270.

  8. Effects of cerebellar transcranial alternating current stimulation on motor cortex excitability and motor function.

    Science.gov (United States)

    Naro, Antonino; Bramanti, Alessia; Leo, Antonino; Manuli, Alfredo; Sciarrone, Francesca; Russo, Margherita; Bramanti, Placido; Calabrò, Rocco Salvatore

    2017-01-07

    The cerebellum regulates several motor functions through two main mechanisms, the cerebellum-brain inhibition (CBI) and the motor surround inhibition (MSI). Although the exact cerebellar structures and functions involved in such processes are partially known, Purkinje cells (PC) and their surrounding interneuronal networks may play a pivotal role concerning CBI and MSI. Cerebellar transcranial alternating current stimulation (tACS) has been proven to shape specific cerebellar components in a feasible, safe, effective, and non-invasive manner. The aim of our study was to characterize the cerebellar structures and functions subtending CBI and MSI using a tACS approach. Fifteen healthy individuals underwent a cerebellar tACS protocol at 10, 50, and 300 Hz, or a sham-tACS over the right cerebellar hemisphere. We measured the tACS aftereffects on motor-evoked potential (MEP) amplitude, CBI induced by tACS (tiCBI) at different frequencies, MSI, and hand motor task performance. None of the participants had any side effect related to tACS. After 50-Hz tACS, we observed a clear tiCBI-50Hz weakening (about +30%, p  0.6). Our preliminary data suggest that PC may represent the last mediator of tiCBI and that the surrounding interneuronal network may have an important role in updating MSI, tiCBI, and M1 excitability during tonic muscle contraction, by acting onto the PC. The knowledge of these neurophysiological issues offers new cues to design innovative, non-invasive neuromodulation protocols to shape cerebellar-cerebral functions.

  9. The contribution of transcranial magnetic stimulation in the functional evaluation of microcircuits in human motor cortex.

    Science.gov (United States)

    Di Lazzaro, Vincenzo; Ziemann, Ulf

    2013-01-01

    Although transcranial magnetic stimulation (TMS) activates a number of different neuron types in the cortex, the final output elicited in corticospinal neurones is surprisingly stereotyped. A single TMS pulse evokes a series of descending corticospinal volleys that are separated from each other by about 1.5 ms (i.e., ~670 Hz). This evoked descending corticospinal activity can be directly recorded by an epidural electrode placed over the high cervical cord. The earliest wave is thought to originate from the direct activation of the axons of fast-conducting pyramidal tract neurones (PTN) and is therefore termed "D" wave. The later waves are thought to originate from indirect, trans-synaptic activation of PTNs and are termed "I" waves. The anatomical and computational characteristics of a canonical microcircuit model of cerebral cortex composed of layer II and III and layer V excitatory pyramidal cells, inhibitory interneurons, and cortico-cortical and thalamo-cortical inputs can account for the main characteristics of the corticospinal activity evoked by TMS including its regular and rhythmic nature, the stimulus intensity-dependence and its pharmacological modulation. In this review we summarize present knowledge of the physiological basis of the effects of TMS of the human motor cortex describing possible interactions between TMS and simple canonical microcircuits of neocortex. According to the canonical model, a TMS pulse induces strong depolarization of the excitatory cells in the superficial layers of the circuit. This leads to highly synchronized recruitment of clusters of excitatory neurons, including layer V PTNs, and of inhibitory interneurons producing a high frequency (~670 Hz) repetitive discharge of the corticospinal axons. The role of the inhibitory circuits is crucial to entrain the firing of the excitatory networks to produce a high-frequency discharge and to control the number and magnitude of evoked excitatory discharge in layer V PTNs. In summary

  10. Inhibitory and facilitatory connectivity from ventral premotor to primary motor cortex in healthy humans at rest--a bifocal TMS study

    DEFF Research Database (Denmark)

    Bäumer, T; Schippling, S; Kroeger, J;

    2009-01-01

    OBJECTIVE: In macaques, intracortical electrical stimulation of ventral premotor cortex (PMv) can modulate ipsilateral primary motor cortex (M1) excitability at short interstimulus intervals (ISIs). METHODS: Adopting the same conditioning-test approach, we used bifocal transcranial magnetic...

  11. Enhancing motor network activity using real-time functional MRI neurofeedback of left premotor cortex

    Directory of Open Access Journals (Sweden)

    Theo Ferreira Marins

    2015-12-01

    Full Text Available Neurofeedback by functional Magnetic Resonance Imaging (fMRI is a technique of potential therapeutic relevance that allows individuals to be aware of their own neurophysiological responses and to voluntarily modulate the activity of specific brain regions, such as the premotor cortex (PMC, important for motor recovery after brain injury. We investigated (i whether healthy human volunteers are able to up-regulate the activity of the left PMC during a right hand finger tapping motor imagery (MI task while receiving continuous fMRI-neurofeedback, and (ii whether successful modulation of brain activity influenced non-targeted motor control regions. During the MI task, participants of the neurofeedback group (NFB received ongoing visual feedback representing the level of fMRI responses within their left PMC. Control (CTL group participants were shown similar visual stimuli, but these were non-contingent on brain activity. Both groups showed equivalent levels of behavioral ratings on arousal and motor imagery, before and during the fMRI protocol. In the NFB, but not in CLT group, brain activation during the last run compared to the first run revealed increased activation in the left PMC. In addition, the NFB group showed increased activation in motor control regions extending beyond the left PMC target area, including the supplementary motor area, basal ganglia and cerebellum. Moreover, in the last run, the NFB group showed stronger activation in the left PMC/inferior frontal gyrus when compared to the CTL group. Our results indicate that modulation of PMC and associated motor control areas can be achieved during a single neurofeedback-fMRI session. These results contribute to a better understanding of the underlying mechanisms of MI-based neurofeedback training, with direct implications for rehabilitation strategies in severe brain disorders, such as stroke.

  12. Real time fMRI: a tool for the routine presurgical localisation of the motor cortex

    Energy Technology Data Exchange (ETDEWEB)

    Moeller, M.; Freund, M.; Schwindt, W.; Gaus, C.; Heindel, W. [University of Muenster, Department of Clinical Radiology, Munster (Germany); Greiner, C. [University of Muenster, Department of Neurosurgery, Munster (Germany)

    2005-02-01

    In patients with brain lesions adjacent to the central area, exact preoperative knowledge of the spatial relation of the tumour to the motor cortex is of major importance. Many studies have shown that functional magnetic resonance imaging (fMRI) is a reliable tool to identify the motor cortex. However, fMRI data acquisition and data processing are time-consuming procedures, and this prevents general routine clinical application. We report a new application of real time fMRI that allows immediate access to fMRI results by automatic on-line data processing. Prior to surgery we examined ten patients with a brain tumour adjacent to the central area. Three measurements were performed at a 1.5-T Magnetom Vision Scanner (Siemens, Forchheim, Germany) on seven patients and at a 1.5-T Intera Scanner (Philips, Best, The Netherlands) on three patients using a sequential finger-tapping paradigm for motor cortex activation versus at rest condition. Blood oxygen level-dependant (BOLD) images were acquired using a multislice EPI sequence (16 slices, TE 60, TR 6000, FOV 210 x 210, matrix 64 x 64). The central sulcus of the left hemisphere could be clearly identified by a maximum of cortical activity after finger tapping of the right hand in all investigated patients. In eight of ten patients the right central sulcus was localised by a signal maximum, whereas in two patients the central sulcus could not be identified due to a hemiparesis in one and strong motion artefacts in the second patient. Finger tapping with one side versus rest condition seems to result in more motion artefacts, while finger tapping of the right versus the left hand yielded the strongest signal in the central area. Real time fMRI is a quick and reliable method to identify the central sulcus and has the potential to become a clinical tool to assess patients non-invasively before neurosurgical treatment. (orig.)

  13. Potential Mechanisms Supporting the Value of Motor Cortex Stimulation to Treat Chronic Pain Syndromes

    Science.gov (United States)

    DosSantos, Marcos F.; Ferreira, Natália; Toback, Rebecca L.; Carvalho, Antônio C.; DaSilva, Alexandre F.

    2016-01-01

    Throughout the first years of the twenty-first century, neurotechnologies such as motor cortex stimulation (MCS), transcranial magnetic stimulation (TMS), and transcranial direct current stimulation (tDCS) have attracted scientific attention and been considered as potential tools to centrally modulate chronic pain, especially for those conditions more difficult to manage and refractory to all types of available pharmacological therapies. Interestingly, although the role of the motor cortex in pain has not been fully clarified, it is one of the cortical areas most commonly targeted by invasive and non-invasive neuromodulation technologies. Recent studies have provided significant advances concerning the establishment of the clinical effectiveness of primary MCS to treat different chronic pain syndromes. Concurrently, the neuromechanisms related to each method of primary motor cortex (M1) modulation have been unveiled. In this respect, the most consistent scientific evidence originates from MCS studies, which indicate the activation of top-down controls driven by M1 stimulation. This concept has also been applied to explain M1-TMS mechanisms. Nevertheless, activation of remote areas in the brain, including cortical and subcortical structures, has been reported with both invasive and non-invasive methods and the participation of major neurotransmitters (e.g., glutamate, GABA, and serotonin) as well as the release of endogenous opioids has been demonstrated. In this critical review, the putative mechanisms underlying the use of MCS to provide relief from chronic migraine and other types of chronic pain are discussed. Emphasis is placed on the most recent scientific evidence obtained from chronic pain research studies involving MCS and non-invasive neuromodulation methods (e.g., tDCS and TMS), which are analyzed comparatively. PMID:26903788

  14. Corticospinal activity evoked and modulated by non-invasive stimulation of the intact human motor cortex.

    Science.gov (United States)

    Di Lazzaro, Vincenzo; Rothwell, John C

    2014-10-01

    A number of methods have been developed recently that stimulate the human brain non-invasively through the intact scalp. The most common are transcranial magnetic stimulation (TMS), transcranial electric stimulation (TES) and transcranial direct current stimulation (TDCS). They are widely used to probe function and connectivity of brain areas as well as therapeutically in a variety of conditions such as depression or stroke. They are much less focal than conventional invasive methods which use small electrodes placed on or in the brain and are often thought to activate all classes of neurones in the stimulated area. However, this is not true. A large body of evidence from experiments on the motor cortex shows that non-invasive methods of brain stimulation can be surprisingly selective and that adjusting the intensity and direction of stimulation can activate different classes of inhibitory and excitatory inputs to the corticospinal output cells. Here we review data that have elucidated the action of TMS and TES, concentrating mainly on the most direct evidence available from spinal epidural recordings of the descending corticospinal volleys. The results show that it is potentially possible to test and condition specific neural circuits in motor cortex that could be affected differentially by disease, or be used in different forms of natural behaviour. However, there is substantial interindividual variability in the specificity of these protocols. Perhaps in the future it will be possible, with the advances currently being made to model the electrical fields induced in individual brains, to develop forms of stimulation that can reliably target more specific populations of neurones, and open up the internal circuitry of the motor cortex for study in behaving humans.

  15. Principal components of hand kinematics and neurophysiological signals in motor cortex during reach to grasp movements.

    Science.gov (United States)

    Mollazadeh, Mohsen; Aggarwal, Vikram; Thakor, Nitish V; Schieber, Marc H

    2014-10-15

    A few kinematic synergies identified by principal component analysis (PCA) account for most of the variance in the coordinated joint rotations of the fingers and wrist used for a wide variety of hand movements. To examine the possibility that motor cortex might control the hand through such synergies, we collected simultaneous kinematic and neurophysiological data from monkeys performing a reach-to-grasp task. We used PCA, jPCA and isomap to extract kinematic synergies from 18 joint angles in the fingers and wrist and analyzed the relationships of both single-unit and multiunit spike recordings, as well as local field potentials (LFPs), to these synergies. For most spike recordings, the maximal absolute cross-correlations of firing rates were somewhat stronger with an individual joint angle than with any principal component (PC), any jPC or any isomap dimension. In decoding analyses, where spikes and LFP power in the 100- to 170-Hz band each provided better decoding than other LFP-based signals, the first PC was decoded as well as the best decoded joint angle. But the remaining PCs and jPCs were predicted with lower accuracy than individual joint angles. Although PCs, jPCs or isomap dimensions might provide a more parsimonious description of kinematics, our findings indicate that the kinematic synergies identified with these techniques are not represented in motor cortex more strongly than the original joint angles. We suggest that the motor cortex might act to sculpt the synergies generated by subcortical centers, superimposing an ability to individuate finger movements and adapt the hand to grasp a wide variety of objects.

  16. Motor Cortex and Motor Cortical Interhemispheric Communication in Walking After Stroke: The Roles of Transcranial Magnetic Stimulation and Animal Models in Our Current and Future Understanding.

    Science.gov (United States)

    Charalambous, Charalambos C; Bowden, Mark G; Adkins, DeAnna L

    2016-01-01

    Despite the plethora of human neurophysiological research, the bilateral involvement of the leg motor cortical areas and their interhemispheric interaction during both normal and impaired human walking is poorly understood. Using transcranial magnetic stimulation (TMS), we have expanded our understanding of the role upper-extremity motor cortical areas play in normal movements and how stroke alters this role, and probed the efficacy of interventions to improve post-stroke arm function. However, similar investigations of the legs have lagged behind, in part, due to the anatomical difficulty in using TMS to stimulate the leg motor cortical areas. Additionally, leg movements are predominately bilaterally controlled and require interlimb coordination that may involve both hemispheres. The sensitive, but invasive, tools used in animal models of locomotion hold great potential for increasing our understanding of the bihemispheric motor cortical control of walking. In this review, we discuss 3 themes associated with the bihemispheric motor cortical control of walking after stroke: (a) what is known about the role of the bihemispheric motor cortical control in healthy and poststroke leg movements, (b) how the neural remodeling of the contralesional hemisphere can affect walking recovery after a stroke, and (c) what is the effect of behavioral rehabilitation training of walking on the neural remodeling of the motor cortical areas bilaterally. For each theme, we discuss how rodent models can enhance the present knowledge on human walking by testing hypotheses that cannot be investigated in humans, and how these findings can then be back-translated into the neurorehabilitation of poststroke walking.

  17. Bilateral lesions of the entorhinal cortex differentially modify haloperidol- and olanzapine-induced c-fos mRNA expression in the rat forebrain.

    Science.gov (United States)

    Seillier, A; Coutureau, E; Thiriet, N; Herbeaux, K; Zwiller, J; Di Scala, G; Will, B; Majchrzak, M

    2003-08-01

    Lesions of the entorhinal cortex are now an accepted model for mimicking some of the neuropathological aspects of schizophrenia, since evidence has accumulated for the presence of cytoarchitectonic abnormalities within this cortex in schizophrenic patients. The present study was undertaken to address the functional consequences of bilateral entorhinal cortex lesions on antipsychotic-induced c-fos expression. After a 15-day recovery period, the effect of a typical antipsychotic, haloperidol (1 mg/kg), on c-fos mRNA expression was compared with that of an atypical one, olanzapine (10 mg/kg), in both sham-lesioned and entorhinal cortex-lesioned rats. In sham-lesioned rats, both haloperidol and olanzapine induced c-fos expression in the caudal cingulate cortex, dorsomedial and dorsolateral caudate-putamen, nucleus accumbens core and shell and lateral septum. In addition, olanzapine, but not haloperidol, increased c-fos expression within the central amygdala. In entorhinal cortex-lesioned rats, haloperidol-induced c-fos expression was markedly reduced in most areas. In contrast, the olanzapine-induced c-fos expression was not altered in the nucleus accumbens shell and lateral septum of the lesioned rats. These findings reveal that entorhinal cortex lesions affect c-fos expression in a compound- and regional-dependent manner. Our results further emphasize the importance of the exploration of the mechanisms of action of antipsychotic drugs in the context of an associated cortical pathology.

  18. The motor cortex drives the muscles during walking in human subjects

    DEFF Research Database (Denmark)

    Petersen, Tue Hvass; Willerslev-Olsen, Maria; Conway, B A;

    2012-01-01

    to address if activity arising in the motor cortex contributes to the muscle activity during gait. Nine healthy human subjects walked on a treadmill at a speed of 3.5–4 km h(-1). Seven of the subjects in addition walked at a speed of 1 km h(-1). Significant coupling between EEG recordings over the leg motor...... area and EMG from the anterior tibial muscle was found in the frequency band 24–40 Hz prior to heel strike during the swing phase of walking. This signifies that rhythmic cortical activity in the 24–40 Hz frequency band is transmitted via the corticospinal tract to the active muscles during walking...

  19. On the functional organization and operational principles of the motor cortex

    DEFF Research Database (Denmark)

    Capaday, Charles; Ethier, Christian; Van Vreeswijk, Carl

    2013-01-01

    Recent studies on the functional organization and operational principles of the motor cortex (MCx), taken together, strongly support the notion that the MCx controls the muscle synergies subserving movements in an integrated manner. For example, during pointing the shoulder, elbow and wrist muscles...... of the movements evoked by activation of each point on its own. This operational principle may simplify the synthesis of motor commands. We will discuss two possible mechanisms that may explain linear summation of outputs. We have observed that the final posture of the arm when pointing to a given spatial location...... to generate the muscle activation patterns (synergies) required to move the arm and hold it in its final position....

  20. Contribution of LFP dynamics to single-neuron spiking variability in motor cortex during movement execution.

    Science.gov (United States)

    Rule, Michael E; Vargas-Irwin, Carlos; Donoghue, John P; Truccolo, Wilson

    2015-01-01

    Understanding the sources of variability in single-neuron spiking responses is an important open problem for the theory of neural coding. This variability is thought to result primarily from spontaneous collective dynamics in neuronal networks. Here, we investigate how well collective dynamics reflected in motor cortex local field potentials (LFPs) can account for spiking variability during motor behavior. Neural activity was recorded via microelectrode arrays implanted in ventral and dorsal premotor and primary motor cortices of non-human primates performing naturalistic 3-D reaching and grasping actions. Point process models were used to quantify how well LFP features accounted for spiking variability not explained by the measured 3-D reach and grasp kinematics. LFP features included the instantaneous magnitude, phase and analytic-signal components of narrow band-pass filtered (δ,θ,α,β) LFPs, and analytic signal and amplitude envelope features in higher-frequency bands. Multiband LFP features predicted single-neuron spiking (1ms resolution) with substantial accuracy as assessed via ROC analysis. Notably, however, models including both LFP and kinematics features displayed marginal improvement over kinematics-only models. Furthermore, the small predictive information added by LFP features to kinematic models was redundant to information available in fast-timescale (<100 ms) spiking history. Overall, information in multiband LFP features, although predictive of single-neuron spiking during movement execution, was redundant to information available in movement parameters and spiking history. Our findings suggest that, during movement execution, collective dynamics reflected in motor cortex LFPs primarily relate to sensorimotor processes directly controlling movement output, adding little explanatory power to variability not accounted by movement parameters.

  1. Contribution of LFP dynamics to single neuron spiking variability in motor cortex during movement execution

    Directory of Open Access Journals (Sweden)

    Michael Everett Rule

    2015-06-01

    Full Text Available Understanding the sources of variability in single-neuron spiking responses is an important open problem for the theory of neural coding. This variability is thought to result primarily from spontaneous collective dynamics in neuronal networks. Here, we investigate how well collective dynamics reflected in motor cortex local field potentials (LFPs can account for spiking variability during motor behavior. Neural activity was recorded via microelectrode arrays implanted in ventral and dorsal premotor and primary motor cortices of non-human primates performing naturalistic 3-D reaching and grasping actions. Point process models were used to quantify how well LFP features accounted for spiking variability not explained by the measured 3-D reach and grasp kinematics. LFP features included the instantaneous magnitude, phase and analytic-signal components of narrow band-pass filtered (δ, θ, α, β LFPs, and analytic signal and amplitude envelope features in higher-frequency bands. Multiband LFP features predicted single-neuron spiking (1ms resolution with substantial accuracy as assessed via ROC analysis. Notably, however, models including both LFP and kinematics features displayed marginal improvement over kinematics-only models. Furthermore, the small predictive information added by LFP features to kinematic models was redundant to information available in fast-timescale (<100ms spiking history. Overall, information in multiband LFP features, although predictive of single-neuron spiking during movement execution, was redundant to information available in movement parameters and spiking history. Our findings suggest that, during movement execution, collective dynamics reflected in motor cortex LFPs primarily relate to sensorimotor processes directly controlling movement output, adding little explanatory power to variability not accounted by movement parameters.

  2. Comparison of functional recovery of manual dexterity after unilateral spinal cord lesion or motor cortex lesion in adult macaque monkeys

    Directory of Open Access Journals (Sweden)

    Florence eHoogewoud

    2013-07-01

    Full Text Available In relation to mechanisms involved in functional recovery of manual dexterity from cervical cord injury or from motor cortical injury, our goal was to determine whether the movements that characterize post-lesion functional recovery are comparable to original movement patterns or do monkeys adopt distinct strategies to compensate the deficits depending on the type of lesion? To this aim, data derived from earlier studies, using a skilled finger task (the modified Brinkman board from which pellets are retrieved from vertical or horizontal slots, in spinal cord and motor cortex injured monkeys were analyzed and compared. Twelve adult macaque monkeys were subjected to a hemi-section of the cervical cord (n=6 or to a unilateral excitotoxic lesion of the hand representation in the primary motor cortex (n=6. In addition, in each subgroup, one half of monkeys (n=3 were treated for 30 days with a function blocking antibody against the neurite growth inhibitory protein Nogo-A, while the other half (n=3 represented control animals. The motor deficits, and the extent and time course of functional recovery were assessed.For some of the parameters investigated (wrist angle for horizontal slots and movement types distribution for vertical slots after cervical injury; movement types distribution for horizontal slots after motor cortex lesion, post-lesion restoration of the original movement patterns (true recovery led to a quantitatively better functional recovery. In the motor cortex lesion groups, pharmacological reversible inactivation experiments showed that the peri-lesion territory of the primary motor cortex or re-arranged, spared domain of the lesion zone, played a major role in the functional recovery, together with the ipsilesional intact premotor cortex.

  3. Exercise combined with low-level GABAA receptor inhibition up-regulates the expression of neurotrophins in the motor cortex.

    Science.gov (United States)

    Takahashi, Kazuma; Maejima, Hiroshi; Ikuta, Gaku; Mani, Hiroki; Asaka, Tadayoshi

    2017-01-01

    Neurotrophins play a crucial role in neuroplasticity, neurogenesis, and neuroprotection in the central nervous system. Aerobic exercise is known to increase the expression of BDNF in the cerebral cortex. Several animal studies have evaluated the tonic inhibition of GABAergic synapses to enhance hippocampal plasticity as well as learning and memory, whereas the effects of GABAergic inhibition on plasticity in the cerebral cortex related to motor learning are not well characterized. The objective of the present study was to examine the interactive effect of low-level GABAA receptor inhibition and exercise on the expression of neurotrophins including BDNF in the murine motor cortex. ICR mice were randomly distributed among 4 groups based on two factors of GABAA receptor inhibition and exercise, i.e. control group, an exercise group, a bicuculline group, and an exercise plus bicuculline group. We administered GABAA receptor antagonist, bicuculline intraperitoneally to the mice (bicuculline and exercise plus bicuculline group) at a non-epileptic dose of 0.25mg/kg, whereas the mice (exercise and exercise plus bicuculline group) were exercised on a treadmill for 1h every day. After two week intervention, the expression of mRNA and protein abundance of neurotrophins in the motor cortex was assayed using Real time PCR and ELISA. BDNF gene expression was significantly increased by approximately 3-fold in the bicuculline group relative to the control, exercise, and bicuculline plus exercise groups. Protein abundance of BDNF expression was significantly increased by approximately 3-fold in the bicuculline plus exercise group relative to other groups. Therefore, the present study revealed that combined GABAA receptor inhibition and moderate aerobic exercise up-regulated BDNF protein expression in the motor cortex without producing side effects on motor or cognitive functions. Alterations in BDNF expression could positively contribute to plasticity by regulating the balance

  4. The Importance of Lateral Connections in the Parietal Cortex for Generating Motor Plans.

    Directory of Open Access Journals (Sweden)

    Derrik E Asher

    Full Text Available Substantial evidence has highlighted the significant role of associative brain areas, such as the posterior parietal cortex (PPC in transforming multimodal sensory information into motor plans. However, little is known about how different sensory information, which can have different delays or be absent, combines to produce a motor plan, such as executing a reaching movement. To address these issues, we constructed four biologically plausible network architectures to simulate PPC: 1 feedforward from sensory input to the PPC to a motor output area, 2 feedforward with the addition of an efference copy from the motor area, 3 feedforward with the addition of lateral or recurrent connectivity across PPC neurons, and 4 feedforward plus efference copy, and lateral connections. Using an evolutionary strategy, the connectivity of these network architectures was evolved to execute visually guided movements, where the target stimulus provided visual input for the entirety of each trial. The models were then tested on a memory guided motor task, where the visual target disappeared after a short duration. Sensory input to the neural networks had sensory delays consistent with results from monkey studies. We found that lateral connections within the PPC resulted in smoother movements and were necessary for accurate movements in the absence of visual input. The addition of lateral connections resulted in velocity profiles consistent with those observed in human and non-human primate visually guided studies of reaching, and allowed for smooth, rapid, and accurate movements under all conditions. In contrast, Feedforward or Feedback architectures were insufficient to overcome these challenges. Our results suggest that intrinsic lateral connections are critical for executing accurate, smooth motor plans.

  5. Development and maturation of embryonic cortical neurons grafted into the damaged adult motor cortex

    Directory of Open Access Journals (Sweden)

    Nissrine Ballout

    2016-08-01

    Full Text Available Injury to the human central nervous system can lead to devastating consequences due to its poor ability to self-repair. Neural transplantation aimed at replacing lost neurons and restore functional circuitry has proven to be a promising therapeutical avenue. We previously reported in adult rodent animal models with cortical lesions that grafted fetal cortical neurons could effectively re-establish specific patterns of projections and synapses. The current study was designed to provide a detailed characterization of the spatio-temporal in vivo development of fetal cortical transplanted cells within the lesioned adult motor cortex and their corresponding axonal projections. We show here that as early as two weeks after grafting, cortical neuroblasts transplanted into damaged adult motor cortex developed appropriate projections to cortical and subcortical targets. Grafted cells initially exhibited characteristics of immature neurons, which then differentiated into mature neurons with appropriate cortical phenotypes where most were glutamatergic and few were GABAergic. All cortical subtypes identified with the specific markers CTIP2, Cux1, FOXP2 and Tbr1 were generated after grafting as evidenced with BrdU co-labeling.The set of data provided here is of interest as it sets biological standards for future studies aimed at replacing fetal cells with embryonic stem cells as a source of cortical neurons.

  6. Motor cortex stimulation for amyotrophic lateral sclerosis. Time for a therapeutic trial?

    Science.gov (United States)

    Di Lazzaro, Vincenzo; Oliviero, Antonio; Saturno, Eleonora; Pilato, Fabio; Dileone, Michele; Sabatelli, Mario; Tonali, Pietro A

    2004-06-01

    Repetitive transcranial magnetic stimulation (rTMS) of the brain can modulate neurotransmission. The aim of this preliminary study was to investigate whether rTMS of the motor cortex at low (1 Hz) or high (20 Hz) frequencies can have any beneficial effect in a transgenic rat model of amyotrophic lateral sclerosis (ALS) and in a few patients with ALS. The effects of chronic rTMS were evaluated in 20 transgenic rats overexpressing the human G93A mutant superoxide dismutase 1 gene. Several cycles of rTMS were also performed in 4 ALS patients and the rate of progression of the disease before and during rTMS treatment was compared. No effects of rTMS was observed in transgenic rats. The rTMS treatment was well tolerated by the patients. All ALS patients continued to deteriorate. However, in the patients exposed to low-frequency rTMS the rate of progression during treatment was slightly slower than that evaluated before treatment; an opposite tendency was observed in patients exposed to high frequencies. Though we cannot be sure whether the effects observed in the patients can be attributed to rTMS, further investigation using low-frequency motor cortex stimulation on a larger group of ALS patients is warranted. The results of the pilot study in humans might open up a new therapeutic perspective in ALS based on neuromodulation.

  7. Facilitating skilled right hand motor function in older subjects by anodal polarization over the left primary motor cortex.

    Science.gov (United States)

    Hummel, Friedhelm C; Heise, Kirstin; Celnik, Pablo; Floel, Agnes; Gerloff, Christian; Cohen, Leonardo G

    2010-12-01

    Healthy ageing is accompanied by limitations in performance of activities of daily living and personal independence. Recent reports demonstrated improvements in motor function induced by noninvasive anodal direct current stimulation (tDCS) of the primary motor cortex (M1) in young healthy adults. Here we tested the hypothesis that a single session of anodal tDCS over left M1 could facilitate performance of right upper extremity tasks required for activities of daily living (Jebsen-Taylor hand function test, JTT) in older subjects relative to Sham in a double-blind cross-over study design. We found (a) significant improvement in JTT function with tDCS relative to Sham that outlasted the stimulation period by at least 30 min, (b) that the older the subjects the more prominent this improvement appeared and (c) that consistent with previous results in younger subjects, these effects were not accompanied by any overt undesired side effect. We conclude that anodal tDCS applied over M1 can facilitate performance of skilled hand functions required for activities of daily living in older subjects.

  8. Primary motor cortex neurons classified in a postural task predict muscle activation patterns in a reaching task.

    Science.gov (United States)

    Heming, Ethan A; Lillicrap, Timothy P; Omrani, Mohsen; Herter, Troy M; Pruszynski, J Andrew; Scott, Stephen H

    2016-04-01

    Primary motor cortex (M1) activity correlates with many motor variables, making it difficult to demonstrate how it participates in motor control. We developed a two-stage process to separate the process of classifying the motor field of M1 neurons from the process of predicting the spatiotemporal patterns of its motor field during reaching. We tested our approach with a neural network model that controlled a two-joint arm to show the statistical relationship between network connectivity and neural activity across different motor tasks. In rhesus monkeys, M1 neurons classified by this method showed preferred reaching directions similar to their associated muscle groups. Importantly, the neural population signals predicted the spatiotemporal dynamics of their associated muscle groups, although a subgroup of atypical neurons reversed their directional preference, suggesting a selective role in antagonist control. These results highlight that M1 provides important details on the spatiotemporal patterns of muscle activity during motor skills such as reaching.

  9. Effects of antiepileptic drugs on associative LTP-like plasticity in human motor cortex.

    Science.gov (United States)

    Heidegger, Tonio; Krakow, Karsten; Ziemann, Ulf

    2010-10-01

    Antiepileptic drugs (AEDs) are used extensively in clinical practice but relatively little is known on their specific effects at the systems level of human cortex. Here we tested, using a double-blind randomized placebo-controlled crossover design in healthy subjects, the effects of a single therapeutic oral dose of seven AEDs with different modes of action (tiagabine, diazepam, gabapentin, lamotrigine, topiramate, levetiracetam and piracetam) on long-term potentiation (LTP)-like motor cortical plasticity induced by paired associative transcranial magnetic stimulation (PAS). PAS-induced LTP-like plasticity was assessed from the increase in motor evoked potential amplitude in a hand muscle contralateral to the stimulated motor cortex. Levetiracetam significantly reduced LTP-like plasticity when compared to the placebo condition. Tiagabine, diazepam, lamotrigine and piracetam resulted in nonsignificant trends towards reduction of LTP-like plasticity while gabapentin and topiramate had no effect. The particularly depressant effect of levetiracetam is probably explained by its unique mode of action through binding at the vesicle membrane protein SV2A. Enhancement of gamma-amino butyric acid-dependent cortical inhibition by tiagabine, diazepam and possibly levetiracetam, and blockage of voltage-gated sodium channels by lamotrigine, may also depress PAS-induced LTP-like plasticity but these mechanisms appear to be less relevant. Findings may inform about AED-related adverse effects on important LTP-dependent central nervous systems processes such as learning or memory formation. The particular depressant effect of levetiracetam on LTP-like plasticity may also relate to the unique properties of this drug to inhibit epileptogenesis, a potentially LTP-associated process.

  10. Dosage-dependent effect of dopamine D2 receptor activation on motor cortex plasticity in humans.

    Science.gov (United States)

    Fresnoza, Shane; Stiksrud, Elisabeth; Klinker, Florian; Liebetanz, David; Paulus, Walter; Kuo, Min-Fang; Nitsche, Michael A

    2014-08-06

    The neuromodulator dopamine plays an important role in synaptic plasticity. The effects depend on receptor subtypes, affinity, concentration level, and the kind of neuroplasticity induced. In animal experiments, dopamine D2-like receptor stimulation revealed partially antagonistic effects on plasticity, which might be explained by dosage dependency. In humans, D2 receptor block abolishes plasticity, and the D2/D3, but predominantly D3, receptor agonist ropinirol has a dosage-dependent nonlinear affect on plasticity. Here we aimed to determine the specific affect of D2 receptor activation on neuroplasticity in humans, because physiological effects of D2 and D3 receptors might differ. Therefore, we combined application of the selective D2 receptor agonist bromocriptine (2.5, 10, and 20 mg or placebo medication) with anodal and cathodal transcranial direct current stimulation (tDCS), which induces nonfocal plasticity, and with paired associative stimulation (PAS) generating a more focal kind of plasticity in the motor cortex of healthy humans. Plasticity was monitored by transcranial magnetic stimulation-induced motor-evoked potential amplitudes. For facilitatory tDCS, bromocriptine prevented plasticity induction independent from drug dosage. However, its application resulted in an inverted U-shaped dose-response curve on inhibitory tDCS, excitability-diminishing PAS, and to a minor degree on excitability-enhancing PAS. These data support the assumption that modulation of D2-like receptor activity exerts a nonlinear dose-dependent effect on neuroplasticity in the human motor cortex that differs from predominantly D3 receptor activation and that the kind of plasticity-induction procedure is relevant for its specific impact.

  11. Stimulus uncertainty enhances long-term potentiation-like plasticity in human motor cortex.

    Science.gov (United States)

    Sale, Martin V; Nydam, Abbey S; Mattingley, Jason B

    2017-03-01

    Plasticity can be induced in human cortex using paired associative stimulation (PAS), which repeatedly and predictably pairs a peripheral electrical stimulus with transcranial magnetic stimulation (TMS) to the contralateral motor region. Many studies have reported small or inconsistent effects of PAS. Given that uncertain stimuli can promote learning, the predictable nature of the stimulation in conventional PAS paradigms might serve to attenuate plasticity induction. Here, we introduced stimulus uncertainty into the PAS paradigm to investigate if it can boost plasticity induction. Across two experimental sessions, participants (n = 28) received a modified PAS paradigm consisting of a random combination of 90 paired stimuli and 90 unpaired (TMS-only) stimuli. Prior to each of these stimuli, participants also received an auditory cue which either reliably predicted whether the upcoming stimulus was paired or unpaired (no uncertainty condition) or did not predict the upcoming stimulus (maximum uncertainty condition). Motor evoked potentials (MEPs) evoked from abductor pollicis brevis (APB) muscle quantified cortical excitability before and after PAS. MEP amplitude increased significantly 15 min following PAS in the maximum uncertainty condition. There was no reliable change in MEP amplitude in the no uncertainty condition, nor between post-PAS MEP amplitudes across the two conditions. These results suggest that stimulus uncertainty may provide a novel means to enhance plasticity induction with the PAS paradigm in human motor cortex. To provide further support to the notion that stimulus uncertainty and prediction error promote plasticity, future studies should further explore the time course of these changes, and investigate what aspects of stimulus uncertainty are critical in boosting plasticity.

  12. Stimulation over primary motor cortex during action observation impairs effector recognition.

    Science.gov (United States)

    Naish, Katherine R; Barnes, Brittany; Obhi, Sukhvinder S

    2016-04-01

    Recent work suggests that motor cortical processing during action observation plays a role in later recognition of the object involved in the action. Here, we investigated whether recognition of the effector making an action is also impaired when transcranial magnetic stimulation (TMS) - thought to interfere with normal cortical activity - is applied over the primary motor cortex (M1) during action observation. In two experiments, single-pulse TMS was delivered over the hand area of M1 while participants watched short clips of hand actions. Participants were then asked whether an image (experiment 1) or a video (experiment 2) of a hand presented later in the trial was the same or different to the hand in the preceding video. In Experiment 1, we found that participants' ability to recognise static images of hands was significantly impaired when TMS was delivered over M1 during action observation, compared to when no TMS was delivered, or when stimulation was applied over the vertex. Conversely, stimulation over M1 did not affect recognition of dot configurations, or recognition of hands that were previously presented as static images (rather than action movie clips) with no object. In Experiment 2, we found that effector recognition was impaired when stimulation was applied part way through (300ms) and at the end (500ms) of the action observation period, indicating that 200ms of action-viewing following stimulation was not long enough to form a new representation that could be used for later recognition. The findings of both experiments suggest that interfering with cortical motor activity during action observation impairs subsequent recognition of the effector involved in the action, which complements previous findings of motor system involvement in object memory. This work provides some of the first evidence that motor processing during action observation is involved in forming representations of the effector that are useful beyond the action observation period.

  13. Motor learning and modulation of prefrontal cortex: an fNIRS assessment

    Science.gov (United States)

    Ono, Yumie; Noah, Jack Adam; Zhang, Xian; Nomoto, Yasunori; Suzuki, Tatsuya; Shimada, Sotaro; Tachibana, Atsumichi; Bronner, Shaw; Hirsch, Joy

    2015-12-01

    Objective. Prefrontal hemodynamic responses are observed during performance of motor tasks. Using a dance video game (DVG), a complex motor task that requires temporally accurate footsteps with given visual and auditory cues, we investigated whether 20 h of DVG training modified hemodynamic responses of the prefrontal cortex in six healthy young adults. Approach. Fronto-temporal activity during actual DVG play was measured using functional near-infrared spectroscopy (fNIRS) pre- and post-training. To evaluate the training-induced changes in the time-courses of fNIRS signals, we employed a regression analysis using the task-specific template fNIRS signals that were generated from alternate well-trained and/or novice DVG players. The HRF was also separately incorporated as a template to construct an alternate regression model. Change in coefficients for template functions at pre- and post- training were determined and compared among different models. Main results. Training significantly increased the motor performance using the number of temporally accurate steps in the DVG as criteria. The mean oxygenated hemoglobin (ΔoxyHb) waveform changed from an activation above baseline pattern to that of a below baseline pattern. Participants showed significantly decreased coefficients for regressors of the ΔoxyHb response of novice players and HRF. The model using ΔoxyHb responses from both well-trained and novice players of DVG as templates showed the best fit for the ΔoxyHb responses of the participants at both pre- and post-training when analyzed with Akaike information criteria. Significance. These results suggest that the coefficients for the template ΔoxyHb responses of the novice players are sensitive indicators of motor learning during the initial stage of training and thus clinically useful to determine the improvement in motor performance when patients are engaged in a specific rehabilitation program.

  14. Frontal Motor Cortex Activity During Reactive Control Is Associated With Past Suicidal Behavior in Recent-Onset Schizophrenia.

    Science.gov (United States)

    Minzenberg, Michael J; Lesh, Tyler; Niendam, Tara; Yoon, Jong H; Cheng, Yaoan; Rhoades, Remy N; Carter, Cameron S

    2015-01-01

    Suicide is prevalent in schizophrenia (SZ), yet the neural system functions that confer suicide risk remain obscure. Circuits operated by the prefrontal cortex (PFC) are altered in SZ, including those that support reactive control, and PFC changes are observed in postmortem studies of heterogeneous suicide victims. We tested whether history of suicide attempt is associated with altered frontal motor cortex activity during reactive control processes. We evaluated 17 patients with recent onset of DSM-IV-TR-defined SZ using the Columbia Suicide Severity Rating Scale and functional magnetic resonance imaging during Stroop task performance. Group-level regression models relating past suicidal behavior to frontal activation controlled for depression, psychosis, and impulsivity. Past suicidal behavior was associated with relatively higher activation in the left-hemisphere supplementary motor area (SMA), pre-SMA, premotor cortex, and dorsolateral PFC, all ipsilateral to the active primary motor cortex. This study provides unique evidence that suicidal behavior in patients with recent-onset SZ directly relates to frontal motor cortex activity during reactive control, in a pattern reciprocal to the relationship with proactive control found previously. Further work should address how frontal-based control functions change with risk over time, and their potential utility as a biomarker for interventions to mitigate suicide risk in SZ.

  15. Perseverative Interference with Object-in-Place Scene Learning in Rhesus Monkeys with Bilateral Ablation of Ventrolateral Prefrontal Cortex

    Science.gov (United States)

    Baxter, Mark G.; Browning, Philip G. F.; Mitchell, Anna S.

    2008-01-01

    Surgical disconnection of the frontal cortex and inferotemporal cortex severely impairs many aspects of visual learning and memory, including learning of new object-in-place scene memory problems, a monkey model of episodic memory. As part of a study of specialization within prefrontal cortex in visual learning and memory, we tested monkeys with…

  16. On the Nature of the Intrinsic Connectivity of the Cat Motor Cortex: Evidence for a Recurrent Neural Network Topology

    DEFF Research Database (Denmark)

    Capaday, Charles; Ethier, C; Brizzi, L

    2009-01-01

    Capaday C, Ethier C, Brizzi L, Sik A, van Vreeswijk C, Gingras D. On the nature of the intrinsic connectivity of the cat motor cortex: evidence for a recurrent neural network topology. J Neurophysiol 102: 2131-2141, 2009. First published July 22, 2009; doi: 10.1152/jn.91319.2008. The details...... and functional significance of the intrinsic horizontal connections between neurons in the motor cortex (MCx) remain to be clarified. To further elucidate the nature of this intracortical connectivity pattern, experiments were done on the MCx of three cats. The anterograde tracer biocytin was ejected...

  17. The effects of rTMS over the primary motor cortex: the link between action and language.

    Science.gov (United States)

    Repetto, Claudia; Colombo, Barbara; Cipresso, Pietro; Riva, Giuseppe

    2013-01-01

    Is the primary motor cortex (M1) necessary for language comprehension? The present study investigates the role of the primary motor cortex during verbs comprehension, within the framework of the embodied theories of language. We applied rTMS over the right and left hand portion of M1 and tested the effects of the stimulation toward the processing of hand-related action verbs versus abstract verbs. Results underlined a specific inhibition effect following left stimulation, only with hand-related action verbs. These findings seem to corroborate the hypothesis of a functional role of M1 in action verbs comprehension.

  18. Influence of position and stimulation parameters on intracortical inhibition and facilitation in human tongue motor cortex.

    Science.gov (United States)

    Kothari, Mohit; Svensson, Peter; Nielsen, Jørgen Feldbæk; Baad-Hansen, Lene

    2014-04-04

    Paired-pulse transcranial magnetic stimulation (ppTMS) can be used to assess short-interval intracortical inhibitory (SICI) and facilitatory (ICF) networks. Many methodological parameters may however influence the outcome. The aim of the study was to examine the influence of body positions (recline and supine), inter-stimulus intervals (ISI) between the test stimulus (TS) and conditioning stimulus (CS) and intensities of the TS and CS on the degree of SICI and ICF. In studies 1 and 2, fourteen and seventeen healthy volunteers participated respectively. ppTMS was applied over the "hot-spot" of the tongue motor cortex and motor evoked potentials (MEPs) were recorded from contralateral tongue muscles. In study 1, single pulse and three ppTMS ISIs, 2, 10, and 15ms, were applied 8 times each in three blocks (TS: 120%, 140% and 160% of resting motor threshold (rMT); CS: 80% of rMT) in two different body positions (recline and supine) randomly. In study 2, single pulse and four ppTMS ISIs, 2, 2.5, 3, and 3.5ms, were applied 8 times each in randomized order in two blocks (CS: 70% and 80% of rMT; TS: 120% of rMT). There was a significant effect of body position (P=0.049), TS intensities (Pmotor pathways using ppTMS and SICI and ICF.

  19. The Truth-Telling Motor Cortex: Response Competition in M1 Discloses Deceptive Behaviour

    Directory of Open Access Journals (Sweden)

    Aviad A. Hadar

    2011-05-01

    Full Text Available Recent studies have suggested that circuits associated with response conflict and response inhibition are strongly implicated in deception. Using single-pulse transcranial magnetic stimulation (TMS, we examined whether conflict between competing responses in primary motor cortex (M1 can be used for discriminating between intentionally false and true facial recognition. Participants used little finger and thumb key-presses to lie or tell the truth regarding their familiarity with a series of famous and nonfamous faces. Single-pulse TMS was administered to M1 at three intervals prior to response execution in order to evoke motor evoked potentials (MEPs in both Abductor Digiti Minimi (ADM and first dorsal interosseous (FDI of the right hand. As predicted, we found that the MEP of the nonresponding digit was greater than the MEP of the responding digit when participants prepared to engage in deception, while a mirror-reversed pattern was observed for truth telling. This effect did not interact with the stimulation interval suggesting consistent activation of the motor plan representing the truth throughout the response preparation process. We discuss these results with reference to models of response selection and procedures for the detection of deception.

  20. Diversity of Layer 5 Projection Neurons in the Mouse Motor Cortex

    Directory of Open Access Journals (Sweden)

    Manfred J Oswald

    2013-10-01

    Full Text Available In the primary motor cortex (M1, layer 5 projection neurons signal directly to distant motor structures to drive movement. Despite their pivotal position and acknowledged diversity these neurons are traditionally separated into broad commissural and corticofugal types, and until now no attempt has been made at resolving the basis for their diversity. We therefore probed the electrophysiological and morphological properties of retrogradely labelled M1 corticospinal (CSp, corticothalamic (CTh, and commissural projecting corticostriatal (CStr and corticocortical (CC neurons. An unsupervised cluster analysis established at least four phenotypes with additional differences between lumbar and cervical projecting CSp neurons. Distinguishing parameters included the action potential (AP waveform, firing behaviour, the hyperpolarisation-activated sag potential, sublayer position, and soma and dendrite size. CTh neurons differed from CSp neurons in showing spike frequency acceleration and a greater sag potential. CStr neurons had the lowest AP amplitude and maximum rise rate of all neurons. Temperature influenced spike train behaviour in corticofugal neurons. At 26 ºC CTh neurons fired bursts of APs more often than CSp neurons, but at 36 ºC both groups fired regular APs. Our findings provide reliable phenotypic fingerprints to identify distinct M1 projection neuron classes as a tool to understand their unique contributions to motor function.

  1. Excitability of the Primary Motor Cortex Increases More Strongly with Slow- than with Normal-Speed Presentation of Actions

    OpenAIRE

    Takefumi Moriuchi; Naoki Iso; Akira Sagari; Kakuya Ogahara; Eiji Kitajima; Koji Tanaka; Takayuki Tabira; Toshio Higashi

    2014-01-01

    Introduction: The aim of the present study was to investigate how the speed of observed action affects the excitability of the primary motor cortex (M1), as assessed by the size of motor evoked potentials (MEPs) induced by transcranial magnetic stimulation (TMS). Copyright: Methods: Eighteen healthy subjects watched a video clip of a person catching a ball, played at three different speeds (normal-, half-, and quarter-speed). MEPs were induced by TMS when the model's hand had opened to the...

  2. Analysis of neural activity in human motor cortex -- Towards brain machine interface system

    Science.gov (United States)

    Secundo, Lavi

    The discovery of directional tuned neurons in the primary motor cortex has advanced motor research in several domains. For instance, in the area of brain machine interface (BMI), researchers have exploited the robust characteristic of tuned motor neurons to allow monkeys to learn control of various machines. In the first chapter of this work we examine whether this phenomena can be observed using the less invasive method of recording electrocorticographic signals (ECoG) from the surface of a human's brain. Our findings reveal that individual ECoG channels contain complex movement information about the neuronal population. While some ECoG channels are tuned to hand movement direction (direction specific channels), others are associated to movement but do not contain information regarding movement direction (non-direction specific channels). More specifically, directionality can vary temporally and by frequency within one channel. In addition, a handful of channels contain no significant information regarding movement at all. These findings strongly suggest that directional and non-directional regions of cortex can be identified with ECoG and provide solutions to decoding movement at the signal resolution provided by ECoG. In the second chapter we examine the influence of movement context on movement reconstruction accuracy. We recorded neuronal signals recorded from electro-corticography (ECoG) during performance of cued- and self-initiated movements. ECoG signals were used to train a reconstruction algorithm to reconstruct continuous hand movement. We found that both cued- and self-initiated movements could be reconstructed with similar accuracy from the ECoG data. However, while an algorithm trained on the cued task could reconstruct performance on a subsequent cued trial, it failed to reconstruct self-initiated arm movement. The same task-specificity was observed when the algorithm was trained with self-initiated movement data and tested on the cued task. Thus

  3. Unconditioned oromotor taste reactivity elicited by sucrose and quinine is unaffected by extensive bilateral damage to the gustatory zone of the insular cortex in rats.

    Science.gov (United States)

    King, Camille Tessitore; Hashimoto, Koji; Blonde, Ginger D; Spector, Alan C

    2015-03-01

    Rats display stereotypical oromotor and somatic responses to small volumes of intraorally infused taste solutions. These behaviors, known as taste reactivity, are categorized by their association with ingestion or rejection and are thought to reflect the palatability of the stimulus. Because supracollicular decerebrate rats display normal taste reactivity responses, it would appear that forebrain structures are not necessary for generating them. However, because moving the plane of transection rostrally, or damaging or manipulating specific ventral forebrain sites disrupts normal taste reactivity behavior, lesions of the gustatory cortex, a region that has been suggested to be involved with palatability processing, may do the same. In the current study, rats received two injections of either ibotenic acid (N=12) or vehicle (N=8), targeting the conventionally defined gustatory cortex in each hemisphere, and were implanted with intraoral cannulae. Following recovery, their responses to intraoral infusions (0.23ml in 1min) of dH2O, sucrose (1.0M and 0.1M), and quinine hydrochloride (3mM and 0.3mM) were video recorded. Analysis of brains with sufficient bilateral lesions (N=10) revealed that, on average, approximately 94% of the gustatory cortex was destroyed. These extensive bilateral lesions had no significant effect on taste reactivity; the numbers of ingestive and aversive responses to sucrose and quinine were similar between groups. Though these findings do not rule out involvement of the gustatory cortex in palatability processing, they make evident that the region of insular cortex destroyed is not necessary for the normal expression of unconditioned affective behavioral responses to taste stimuli.

  4. Reinforcement learning of targeted movement in a spiking neuronal model of motor cortex.

    Directory of Open Access Journals (Sweden)

    George L Chadderdon

    Full Text Available Sensorimotor control has traditionally been considered from a control theory perspective, without relation to neurobiology. In contrast, here we utilized a spiking-neuron model of motor cortex and trained it to perform a simple movement task, which consisted of rotating a single-joint "forearm" to a target. Learning was based on a reinforcement mechanism analogous to that of the dopamine system. This provided a global reward or punishment signal in response to decreasing or increasing distance from hand to target, respectively. Output was partially driven by Poisson motor babbling, creating stochastic movements that could then be shaped by learning. The virtual forearm consisted of a single segment rotated around an elbow joint, controlled by flexor and extensor muscles. The model consisted of 144 excitatory and 64 inhibitory event-based neurons, each with AMPA, NMDA, and GABA synapses. Proprioceptive cell input to this model encoded the 2 muscle lengths. Plasticity was only enabled in feedforward connections between input and output excitatory units, using spike-timing-dependent eligibility traces for synaptic credit or blame assignment. Learning resulted from a global 3-valued signal: reward (+1, no learning (0, or punishment (-1, corresponding to phasic increases, lack of change, or phasic decreases of dopaminergic cell firing, respectively. Successful learning only occurred when both reward and punishment were enabled. In this case, 5 target angles were learned successfully within 180 s of simulation time, with a median error of 8 degrees. Motor babbling allowed exploratory learning, but decreased the stability of the learned behavior, since the hand continued moving after reaching the target. Our model demonstrated that a global reinforcement signal, coupled with eligibility traces for synaptic plasticity, can train a spiking sensorimotor network to perform goal-directed motor behavior.

  5. Priming theta burst stimulation enhances motor cortex plasticity in young but not old adults.

    Science.gov (United States)

    Opie, George M; Vosnakis, Eleni; Ridding, Michael C; Ziemann, Ulf; Semmler, John G

    Primary motor cortex neuroplasticity is reduced in old adults, which may contribute to the motor deficits commonly observed in the elderly. Previous research in young subjects suggests that the neuroplastic response can be enhanced using non-invasive brain stimulation (NIBS), with a larger plastic response observed following priming with both long-term potentiation (LTP) and depression (LTD)-like protocols. However, it is not known if priming stimulation can also modulate plasticity in older adults. To investigate if priming NIBS can be used to modulate motor cortical plasticity in old subjects. In 16 young (22.3 ± 1.0 years) and 16 old (70.2 ± 1.7 years) subjects, we investigated the response to intermittent theta burst stimulation (iTBS; LTP-like) when applied 10 min after sham stimulation, continuous TBS (cTBS; LTD-like) or an identical block of iTBS. Corticospinal plasticity was assessed by recording changes in motor evoked potential (MEP) amplitude. In young subjects, priming with cTBS (cTBS + iTBS) resulted in larger MEPs than priming with either iTBS (iTBS + iTBS; P = 0.001) or sham (sham + iTBS; P  0.9), whereas the response to cTBS + iTBS was reduced relative to iTBS + iTBS (P = 0.02) and sham + iTBS (P = 0.04). Priming TBS is ineffective for modifying M1 plasticity in older adults, which may limit the therapeutic use of priming stimulation in neurological conditions common in the elderly. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Reinforcement learning of targeted movement in a spiking neuronal model of motor cortex.

    Science.gov (United States)

    Chadderdon, George L; Neymotin, Samuel A; Kerr, Cliff C; Lytton, William W

    2012-01-01

    Sensorimotor control has traditionally been considered from a control theory perspective, without relation to neurobiology. In contrast, here we utilized a spiking-neuron model of motor cortex and trained it to perform a simple movement task, which consisted of rotating a single-joint "forearm" to a target. Learning was based on a reinforcement mechanism analogous to that of the dopamine system. This provided a global reward or punishment signal in response to decreasing or increasing distance from hand to target, respectively. Output was partially driven by Poisson motor babbling, creating stochastic movements that could then be shaped by learning. The virtual forearm consisted of a single segment rotated around an elbow joint, controlled by flexor and extensor muscles. The model consisted of 144 excitatory and 64 inhibitory event-based neurons, each with AMPA, NMDA, and GABA synapses. Proprioceptive cell input to this model encoded the 2 muscle lengths. Plasticity was only enabled in feedforward connections between input and output excitatory units, using spike-timing-dependent eligibility traces for synaptic credit or blame assignment. Learning resulted from a global 3-valued signal: reward (+1), no learning (0), or punishment (-1), corresponding to phasic increases, lack of change, or phasic decreases of dopaminergic cell firing, respectively. Successful learning only occurred when both reward and punishment were enabled. In this case, 5 target angles were learned successfully within 180 s of simulation time, with a median error of 8 degrees. Motor babbling allowed exploratory learning, but decreased the stability of the learned behavior, since the hand continued moving after reaching the target. Our model demonstrated that a global reinforcement signal, coupled with eligibility traces for synaptic plasticity, can train a spiking sensorimotor network to perform goal-directed motor behavior.

  7. Acute Exposure to Pacific Ciguatoxin Reduces Electroencephalogram Activity and Disrupts Neurotransmitter Metabolic Pathways in Motor Cortex.

    Science.gov (United States)

    Kumar, Gajendra; Au, Ngan Pan Bennett; Lei, Elva Ngai Yu; Mak, Yim Ling; Chan, Leanne Lai Hang; Lam, Michael Hon Wah; Chan, Leo Lai; Lam, Paul Kwan Sing; Ma, Chi Him Eddie

    2016-09-10

    Ciguatera fish poisoning (CFP) is a common human food poisoning caused by consumption of ciguatoxin (CTX)-contaminated fish affecting over 50,000 people worldwide each year. CTXs are classified depending on their origin from the Pacific (P-CTXs), Indian Ocean (I-CTXs), and Caribbean (C-CTXs). P-CTX-1 is the most toxic CTX known and the major source of CFP causing an array of neurological symptoms. Neurological symptoms in some CFP patients last for several months or years; however, the underlying electrophysiological properties of acute exposure to CTXs remain unknown. Here, we used CTX purified from ciguatera fish sourced in the Pacific Ocean (P-CTX-1). Delta and theta electroencephalography (EEG) activity was reduced remarkably in 2 h and returned to normal in 6 h after a single exposure. However, second exposure to P-CTX-1 induced not only a further reduction in EEG activities but also a 2-week delay in returning to baseline EEG values. Ciguatoxicity was detected in the brain hours after the first and second exposure by mouse neuroblastoma assay. The spontaneous firing rate of single motor cortex neuron was reduced significantly measured by single-unit recording with high spatial resolution. Expression profile study of neurotransmitters using targeted profiling approach based on liquid chromatography-tandem mass spectrometry revealed an imbalance between excitatory and inhibitory neurotransmitters in the motor cortex. Our study provides a possible link between the brain oscillations and neurotransmitter release after acute exposure to P-CTX-1. Identification of EEG signatures and major metabolic pathways affected by P-CTX-1 provides new insight into potential biomarker development and therapeutic interventions.

  8. Direct-current-dependent shift of theta-burst-induced plasticity in the human motor cortex.

    Science.gov (United States)

    Hasan, Alkomiet; Hamada, Masashi; Nitsche, Michael A; Ruge, Diane; Galea, Joseph M; Wobrock, Thomas; Rothwell, John C

    2012-03-01

    Animal studies using polarising currents have shown that induction of synaptic long-term potentiation (LTP) and long-term depression (LTD) by bursts of patterned stimulation is affected by the membrane potential of the postsynaptic neurone. The aim of the present experiments was to test whether it is possible to observe similar phenomena in humans with the aim of improving present protocols of inducing synaptic plasticity for therapeutic purposes. We tested whether the LTP/LTD-like after effects of transcranial theta-burst stimulation (TBS) of human motor cortex, an analogue of patterned electrical stimulation in animals, were affected by simultaneous transcranial direct-current stimulation (tDCS), a non-invasive method of polarising cortical neurones in humans. Nine healthy volunteers were investigated in a single-blind, balanced cross-over study; continuous TBS (cTBS) was used to introduce LTD-like after effects, whereas intermittent TBS (iTBS) produced LTP-like effects. Each pattern was coupled with concurrent application of tDCS (motor thresholds and intracortical inhibitory/facilitatory networks were not altered by any of the stimulation protocols. We conclude that the after effects of TBS can be modulated by concurrent tDCS. We hypothesise that tDCS changes the membrane potential of the apical dendrites of cortical pyramidal neurones and that this changes the response to patterned synaptic input evoked by TBS. The data show that it may be possible to enhance LTP-like plasticity after TBS in the human cortex.

  9. Accurate stepping on a narrow path: mechanics, EMG, and motor cortex activity in the cat.

    Science.gov (United States)

    Farrell, Brad J; Bulgakova, Margarita A; Sirota, Mikhail G; Prilutsky, Boris I; Beloozerova, Irina N

    2015-11-01

    How do cats manage to walk so graciously on top of narrow fences or windowsills high above the ground while apparently exerting little effort? In this study we investigated cat full-body mechanics and the activity of limb muscles and motor cortex during walking along a narrow 5-cm path on the ground. We tested the hypotheses that during narrow walking 1) lateral stability would be lower because of the decreased base-of-support area and 2) the motor cortex activity would increase stride-related modulation because of imposed demands on lateral stability and paw placement accuracy. We measured medio-lateral and rostro-caudal dynamic stability derived from the extrapolated center of mass position with respect to the boundaries of the support area. We found that cats were statically stable in the frontal plane during both unconstrained and narrow-path walking. During narrow-path walking, cats walked slightly slower with more adducted limbs, produced smaller lateral forces by hindlimbs, and had elevated muscle activities. Of 174 neurons recorded in cortical layer V, 87% of forelimb-related neurons (from 114) and 90% of hindlimb-related neurons (from 60) had activities during narrow-path walking distinct from unconstrained walking: more often they had a higher mean discharge rate, lower depth of stride-related modulation, and/or longer period of activation during the stride. These activity changes appeared to contribute to control of accurate paw placement in the medio-lateral direction, the width of the stride, rather than to lateral stability control, as the stability demands on narrow-path and unconstrained walking were similar.

  10. Motor and parietal cortex stimulation for phantom limb pain and sensations.

    Science.gov (United States)

    Bolognini, Nadia; Olgiati, Elena; Maravita, Angelo; Ferraro, Francesco; Fregni, Felipe

    2013-08-01

    Limb amputation may lead to chronic painful sensations referred to the absent limb, ie phantom limb pain (PLP), which is likely subtended by maladaptive plasticity. The present study investigated whether transcranial direct current stimulation (tDCS), a noninvasive technique of brain stimulation that can modulate neuroplasticity, can reduce PLP. In 2 double-blind, sham-controlled experiments in subjects with unilateral lower or upper limb amputation, we measured the effects of a single session of tDCS (2 mA, 15 min) of the primary motor cortex (M1) and of the posterior parietal cortex (PPC) on PLP, stump pain, nonpainful phantom limb sensations and telescoping. Anodal tDCS of M1 induced a selective short-lasting decrease of PLP, whereas cathodal tDCS of PPC induced a selective short-lasting decrease of nonpainful phantom sensations; stump pain and telescoping were not affected by parietal or by motor tDCS. These findings demonstrate that painful and nonpainful phantom limb sensations are dissociable phenomena. PLP is associated primarily with cortical excitability shifts in the sensorimotor network; increasing excitability in this system by anodal tDCS has an antalgic effect on PLP. Conversely, nonpainful phantom sensations are associated to a hyperexcitation of PPC that can be normalized by cathodal tDCS. This evidence highlights the relationship between the level of excitability of different cortical areas, which underpins maladaptive plasticity following limb amputation and the phenomenology of phantom limb, and it opens up new opportunities for the use of tDCS in the treatment of PLP.

  11. Primary motor cortex of the parkinsonian monkey: altered encoding of active movement.

    Science.gov (United States)

    Pasquereau, Benjamin; DeLong, Mahlon R; Turner, Robert S

    2016-01-01

    Abnormalities in the movement-related activation of the primary motor cortex (M1) are thought to be a major contributor to the motor signs of Parkinson's disease. The existing evidence, however, variably indicates that M1 is under-activated with movement, overactivated (due to a loss of functional specificity) or activated with abnormal timing. In addition, few models consider the possibility that distinct cortical neuron subtypes may be affected differently. Those gaps in knowledge were addressed by studying the extracellular activity of antidromically-identified lamina 5b pyramidal-tract type neurons (n = 153) and intratelencephalic-type corticostriatal neurons (n = 126) in the M1 of two monkeys as they performed a step-tracking arm movement task. We compared movement-related discharge before and after the induction of parkinsonism by administration of MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) and quantified the spike rate encoding of specific kinematic parameters of movement using a generalized linear model. The fraction of M1 neurons with movement-related activity declined following MPTP but only marginally. The strength of neuronal encoding of parameters of movement was reduced markedly (mean 29% reduction in the coefficients from the generalized linear model). This relative decoupling of M1 activity from kinematics was attributable to reductions in the coefficients that estimated the spike rate encoding of movement direction (-22%), speed (-40%), acceleration (-49%) and hand position (-33%). After controlling for MPTP-induced changes in motor performance, M1 activity related to movement itself was reduced markedly (mean 36% hypoactivation). This reduced activation was strong in pyramidal tract-type neurons (-50%) but essentially absent in corticostriatal neurons. The timing of M1 activation was also abnormal, with earlier onset times, prolonged response durations, and a 43% reduction in the prevalence of movement-related changes beginning in the 150

  12. A combined TMS-EEG study of short-latency afferent inhibition in the motor and dorsolateral prefrontal cortex.

    Science.gov (United States)

    Noda, Yoshihiro; Cash, Robin F H; Zomorrodi, Reza; Dominguez, Luis Garcia; Farzan, Faranak; Rajji, Tarek K; Barr, Mera S; Chen, Robert; Daskalakis, Zafiris J; Blumberger, Daniel M

    2016-09-01

    Combined transcranial magnetic stimulation and electroencephalography (TMS-EEG) enables noninvasive neurophysiological investigation of the human cortex. A TMS paradigm of short-latency afferent inhibition (SAI) is characterized by attenuation of the motor-evoked potential (MEP) and modulation of N100 of the TMS-evoked potential (TEP) when TMS is delivered to motor cortex (M1) following median nerve stimulation. SAI is a marker of cholinergic activity in the motor cortex; however, the SAI has not been tested from the prefrontal cortex. We aimed to explore the effect of SAI in dorsolateral prefrontal cortex (DLPFC). SAI was examined in 12 healthy subjects with median nerve stimulation and TMS delivered to M1 and DLPFC at interstimulus intervals (ISIs) relative to the individual N20 latency. SAI in M1 was tested at the optimal ISI of N20 + 2 ms. SAI in DLPFC was investigated at a range of ISI from N20 + 2 to N20 + 20 ms to explore its temporal profile. For SAI in M1, the attenuation of MEP amplitude was correlated with an increase of TEP N100 from the left central area. A similar spatiotemporal neural signature of SAI in DLPFC was observed with a marked increase of N100 amplitude. SAI in DLPFC was maximal at ISI N20 + 4 ms at the left frontal area. These findings establish the neural signature of SAI in DLPFC. Future studies could explore whether DLPFC-SAI is neurophysiological marker of cholinergic dysfunction in cognitive disorders.

  13. The involvement of the left motor cortex in learning of a novel action word lexicon.

    Science.gov (United States)

    Liuzzi, Gianpiero; Freundlieb, Nils; Ridder, Volker; Hoppe, Julia; Heise, Kirstin; Zimerman, Maximo; Dobel, Christian; Enriquez-Geppert, Stefanie; Gerloff, Christian; Zwitserlood, Pienie; Hummel, Friedhelm C

    2010-10-12

    Current theoretical positions assume that action-related word meanings are established by functional connections between perisylvian language areas and the motor cortex (MC) according to Hebb's associative learning principle. To test this assumption, we probed the functional relevance of the left MC for learning of a novel action word vocabulary by disturbing neural plasticity in the MC with transcranial direct current stimulation (tDCS). In combination with tDCS, subjects learned a novel vocabulary of 76 concrete, body-related actions by means of an associative learning paradigm. Compared with a control condition with "sham" stimulation, cathodal tDCS reduced success rates in vocabulary acquisition, as shown by tests of novel action word translation into the native language. The analysis of learning behavior revealed a specific effect of cathodal tDCS on the ability to associatively couple actions with novel words. In contrast, we did not find these effects in control experiments, when tDCS was applied to the prefrontal cortex or when subjects learned object-related words. The present study lends direct evidence to the proposition that the left MC is causally involved in the acquisition of novel action-related words. Copyright © 2010 Elsevier Ltd. All rights reserved.

  14. Effects of the Bee Venom Herbal Acupuncture on the Neurotransmitters of the Rat Brain Cortex

    Directory of Open Access Journals (Sweden)

    Hyoung-Seok Yun

    2001-02-01

    Full Text Available In order to study the effects of bee venom Herbal Acupuncture on neurotransmitters in the rat brain cortex, herbal acupuncture with bee venom group and normal saline group was performed at LI4 bilaterally of the rat. the average optical density of neurotransmitters from the cerebral cortex was analysed 30 minutes after the herbal aqupuncture, by the immunohistochemistry. The results were as follows: 1. The density of NADPH-diaphorase in bee venom group was increased significantly at the motor cortex, visual cortex, auditory cortex, cingulate cortex, retrosplenial cortex and perirhinal cortex compared to the normal saline group. 2. The average optical density of vasoactive intestinal peptide in bee venom group had significant changes at the insular cortex, retrosplenial cortex and perirhinal cortex, compared to the normal saline group. 3. The average optical density of neuropeptide-Y in bee venom group increased significantly at the visual cortex and cingulate cortex, compared to the normal saline group.

  15. The Contribution of Primary Motor Cortex Is Essential for Probabilistic Implicit Sequence Learning: Evidence from Theta Burst Magnetic Stimulation

    Science.gov (United States)

    Wilkinson, Leonora; Teo, James T.; Obeso, Ignacio; Rothwell, John C.; Jahanshahi, Marjan

    2010-01-01

    Theta burst transcranial magnetic stimulation (TBS) is considered to produce plastic changes in human motor cortex. Here, we examined the inhibitory and excitatory effects of TBS on implicit sequence learning using a probabilistic serial reaction time paradigm. We investigated the involvement of several cortical regions associated with implicit…

  16. Neural mechanism of activity spread in the cat motor cortex and its relation to the intrinsic connectivity

    DEFF Research Database (Denmark)

    Capaday, Charles; van Vreeswijk, Carl; Ethier, Christian

    2011-01-01

    NON TECHNICAL SUMMARY{NBSP}: The motor cortex (MCx) is an important brain region that initiates and controls voluntary movements. Neurons in MCx are anatomically connected by recurrent (feedback) networks. This connectivity pattern allows neurons to communicate reciprocally with each other potent...

  17. Modulation of connexin 36 expression in basal ganglia and motor cortex in rat model of Parkinson's disease

    Directory of Open Access Journals (Sweden)

    CHEN Xian-wen

    2013-08-01

    Full Text Available Objective To observe the expression of connexin 36 (Cx36 in the striatum and motor cortex of rat model of Parkinson's disease (PD in order to explore whether gap junction is involved in the pathogenesis of the cortex-basal ganglia circuit disturbances in PD. Methods Hemi-parkinsonian rat model was produced by stereotaxically injecting 6-hydroxydopamine (6-OHDA to right medial forebrain bundle (MFB. Immunohistochemical staining and Western blotting analysis were used to observe the expression changes of Cx36 in the striatum and motor cortex. Double immunofluorescence labeling was used to analyze the expression of Cx36 in enkephalin (ENK positive medium spiny neurons and Parvalbumin (PV positive interneurons in the striatum. Results Immunohistochemical staining showed Cx36 expression was elevated in the right striatum as well as right motor cortex of PD group compared with normal control group (t = 2.474, P = 0.048; t = 2.614, P = 0.040. Double immunofluorescence labeling staining revealed that ENK-positive striatum neurons were elevated (t = 3.987, P = 0.007 and Cx36 expression was increased in ENK-positive striatum neurons (t = 3.271, P = 0.017 in PD group compared with normal control group. While PV-positive interneurons decreased (t = 2.777, P = 0.032 and Cx36 expression was down-regulated in PV-positive interneurons (t = 2.624, P = 0.039 compared with the normal control group. Western blotting indicated that the 6-OHDA lesion induced a significant upregulation of Cx36 to (119.31 ± 8.92% in comparison with the normal group [(104.05 ± 3.82%] in right striatum (t = 3.516, P = 0.024. In right motor cortex Cx36 increased to (138.20 ± 17.88% , induced a significant upregulation of Cx36 in the right motor cortex in comparison with the normal control group [(105.27 ± 2.82%; t = 4.068, P = 0.015]. Conclusion The Cx36 expression was generally increased in the striatum and motor cortex of PD rat model, with upregulation in ENK-positive striatum

  18. Interhemispheric interactions between trunk muscle representations of the primary motor cortex.

    Science.gov (United States)

    Jean-Charles, Loyda; Nepveu, Jean-Francois; Deffeyes, Joan E; Elgbeili, Guillaume; Dancause, Numa; Barthélemy, Dorothy

    2017-09-01

    Unilateral arm movements require trunk stabilization through bilateral contraction of axial muscles. Interhemispheric interactions between primary motor cortices (M1) could enable such coordinated contractions, but these mechanisms are largely unknown. Using transcranial magnetic stimulation (TMS), we characterized interhemispheric interactions between M1 representations of the trunk-stabilizing muscles erector spinae at the first lumbar vertebra (ES L1) during a right isometric shoulder flexion. These interactions were compared with those of the anterior deltoid (AD), the main agonist in this task, and the first dorsal interosseous (FDI). TMS over the right M1 elicited ipsilateral silent periods (iSP) in all three muscles on the right side. In ES L1, but not in AD or FDI, ipsilateral motor evoked potential (iMEP) could precede the iSP or replace it. iMEP amplitude was not significantly different whether ES L1 was used to stabilize the trunk or was voluntarily contracted. TMS at the cervicomedullary junction showed that the size of cervicomedullary evoked potential was unchanged during the iSP but increased during iMEP, suggesting that the iSP, but not the iMEP, is due to intracortical mechanisms. Using a dual-coil paradigm with two coils over the left and right M1, interhemispheric inhibition could be evoked at interstimulus intervals of 6 ms in ES L1 and 8 ms in AD and FDI. Together, these results suggest that interhemispheric inhibition is dominant when axial muscles are involved in a stabilizing task. The ipsilateral facilitation could be evoked by ipsilateral or subcortical pathways and could be used depending on the role axial muscles play in the task.NEW & NOTEWORTHY The mechanisms involved in the bilateral coordination of axial muscles during unilateral arm movement are poorly understood. We thus investigated the nature of interhemispheric interactions in axial muscles during arm motor tasks in healthy subjects. By combining different methodologies, we

  19. Motor association cortex activity in Parkinson`s disease. A functional MRI study

    Energy Technology Data Exchange (ETDEWEB)

    Tada, Yukiko [Yamaguchi Univ., Ube (Japan). School of Medicine

    1998-08-01

    The purpose of this study was to examine the activation of motor association cortex using functional magnetic resonance imaging (fMRI) in patients with Parkinson`s disease (PD) and control subjects during performed hand movements. There were 26 patients with PD (12 patients with Hoehn and Yahr stage I-II, 14 patients with stage III) and 8 control subjects. Functional imaging was performed using a 1.5 tesla MRI system equipped with a single-shot, echo-planar pulse sequence. The significant signal changes were observed within the primary sensorimotor area, the supplementary motor area (SMA), and the parietal association area in both PD and control subjects. In PD subjects, the SMA was less activated than in control subjects; there were significant differences in the number of pixels activated in SMA between control and Yahr III group (p<0.01), and between Yahr I-II and Yahr III group (p<0.01). Our results demonstrated that movement related cerebral activity in the SMA is reduced in PD subjects, consistent with previously published data using other methods. It is well known from anatomical studies that one of the major cortical outputs of the basal ganglia is the SMA. This may explain the hypoactivation of the SMA in PD. Studies using fMRI provide a promising method not only for localizing cortical activation related to voluntary movements but also for investigating pathophysiology of movement disorders. (author)

  20. Reduced functional connectivity within the primary motor cortex of patients with brachial plexus injury

    Directory of Open Access Journals (Sweden)

    D. Fraiman

    2016-01-01

    Full Text Available This study aims at the effects of traumatic brachial plexus lesion with root avulsions (BPA upon the organization of the primary motor cortex (M1. Nine right-handed patients with a right BPA in whom an intercostal to musculocutaneous (ICN-MC nerve transfer was performed had post-operative resting state fMRI scanning. The analysis of empirical functional correlations between neighboring voxels revealed faster correlation decay as a function of distance in the M1 region corresponding to the arm in BPA patients as compared to the control group. No differences between the two groups were found in the face area. We also investigated whether such larger decay in patients could be attributed to a gray matter diminution in M1. Structural imaging analysis showed no difference in gray matter density between groups. Our findings suggest that the faster decay in neighboring functional correlations without significant gray matter diminution in BPA patients could be related to a reduced activity in intrinsic horizontal connections in M1 responsible for upper limb motor synergies.

  1. Double dissociation between motor and visual imagery in the posterior parietal cortex.

    Science.gov (United States)

    Pelgrims, Barbara; Andres, Michael; Olivier, Etienne

    2009-10-01

    Because motor imagery (MI) and visual imagery (VI) are influenced differently by factors such as biomechanical constraints or stimulus size, it is conceivable that they rely on separate processes, possibly involving distinct cortical networks, a view corroborated by neuroimaging and neuropsychological studies. In the posterior parietal cortex, it has been suggested that the superior parietal lobule (SPL) underlies VI, whereas MI relies on the supramarginalis gyrus (SMG). However, because several brain imaging studies have also shown an overlap of activations in SPL and SMG during VI or MI, the question arises as to which extent these 2 subregions really contribute to distinct imagery processes. To address this issue, we used repetitive transcranial magnetic stimulation to induce virtual lesions of either SMG or SPL in subjects performing a MI (hand drawing rotation) or a VI (letter rotation) task. Whatever hemisphere was stimulated, SMG lesions selectively altered MI, whereas SPL lesions only affected VI, demonstrating a double dissociation between MI and VI. Because these deficits were not influenced by the angular distance of the stimuli, we suggest that SMG and SPL are involved in the reenactment of the motor and visual representations, respectively, and not in mental rotation processes per se.

  2. Reduced functional connectivity within the primary motor cortex of patients with brachial plexus injury.

    Science.gov (United States)

    Fraiman, D; Miranda, M F; Erthal, F; Buur, P F; Elschot, M; Souza, L; Rombouts, S A R B; Schimmelpenninck, C A; Norris, D G; Malessy, M J A; Galves, A; Vargas, C D

    2016-01-01

    This study aims at the effects of traumatic brachial plexus lesion with root avulsions (BPA) upon the organization of the primary motor cortex (M1). Nine right-handed patients with a right BPA in whom an intercostal to musculocutaneous (ICN-MC) nerve transfer was performed had post-operative resting state fMRI scanning. The analysis of empirical functional correlations between neighboring voxels revealed faster correlation decay as a function of distance in the M1 region corresponding to the arm in BPA patients as compared to the control group. No differences between the two groups were found in the face area. We also investigated whether such larger decay in patients could be attributed to a gray matter diminution in M1. Structural imaging analysis showed no difference in gray matter density between groups. Our findings suggest that the faster decay in neighboring functional correlations without significant gray matter diminution in BPA patients could be related to a reduced activity in intrinsic horizontal connections in M1 responsible for upper limb motor synergies.

  3. Theta-burst repetitive transcranial magnetic stimulation suppresses specific excitatory circuits in the human motor cortex.

    Science.gov (United States)

    Di Lazzaro, V; Pilato, F; Saturno, E; Oliviero, A; Dileone, M; Mazzone, P; Insola, A; Tonali, P A; Ranieri, F; Huang, Y Z; Rothwell, J C

    2005-06-15

    In four conscious patients who had electrodes implanted in the cervical epidural space for the control of pain, we recorded corticospinal volleys evoked by single-pulse transcranial magnetic stimulation (TMS) over the motor cortex before and after a 20 s period of continuous theta-burst stimulation (cTBS). It has previously been reported that this form of repetitive TMS reduces the amplitude of motor-evoked potentials (MEPs), with the maximum effect occurring at 5-10 min after the end of stimulation. The present results show that cTBS preferentially decreases the amplitude of the corticospinal I1 wave, with approximately the same time course. This is consistent with a cortical origin of the effect on the MEP. However, other protocols that lead to MEP suppression, such as short-interval intracortical inhibition, are characterized by reduced excitability of late I waves (particularly I3), suggesting that cTBS suppresses MEPs through different mechanisms, such as long-term depression in excitatory synaptic connections.

  4. Excitability changes in primary motor cortex just prior to voluntary muscle relaxation.

    Science.gov (United States)

    Suzuki, Tomotaka; Sugawara, Kenichi; Takagi, Mineko; Higashi, Toshio

    2015-01-01

    We postulated that primary motor cortex (M1) activity does not just decrease immediately prior to voluntary muscle relaxation; rather, it is dynamic and acts as an active cortical process. Thus we investigated the detailed time course of M1 excitability changes during muscle relaxation. Ten healthy participants performed a simple reaction time task. After the go signal, they rapidly terminated isometric abduction of the right index finger from a constant muscle force output of 20% of their maximal voluntary contraction force and performed voluntary muscle relaxation. Transcranial magnetic stimulation pulses were randomly delivered before and after the go signal, and motor evoked potentials (MEPs) were recorded from the right first dorsal interosseous muscle. We selected the time course relative to an appropriate reference point, the onset of voluntary relaxation, to detect excitability changes in M1. MEP amplitude from 80 to 60 ms before the estimated electromyographic offset was significantly greater than that in other intervals. Dynamic excitability changes in M1 just prior to quick voluntary muscle relaxation indicate that cortical control of muscle relaxation is established through active processing and not by simple cessation of activity. The cortical mechanisms underlying muscle relaxation need to be reconsidered in light of such dynamics. Copyright © 2015 the American Physiological Society.

  5. An improvement in perception of self-generated tactile stimuli following theta-burst stimulation of primary motor cortex

    Science.gov (United States)

    Voss, Martin; Bays, Paul M.; Rothwell, John C.; Wolpert, Daniel M.

    2007-01-01

    Recent studies have shown that self-generated tactile sensations are perceived as weaker than the same sensations externally generated. This has been linked to a central comparator mechanism that uses efference copy to attenuate the predictable component of sensory inputs arising from one's own actions in order to enhance the salience of external stimuli. To provide a quantitative measure of this attenuation, a force-matching task was developed in which subjects experience a force applied to their finger and are then required to match the perceived force by actively pushing on the finger using their other hand. The attenuation of predictable sensory input results in subjects producing a larger active force than was experienced passively. Here, we have examined the effects of a novel rTMS protocol, theta-burst stimulation (TBS), over primary motor cortex on this attenuation. TBS can alter the excitability of motor cortex to incoming activity. We show that application of a 20 s continuous train of TBS, that depresses motor cortex, significantly improves performance in a force-matching task. This suggests that the TBS intervention disturbed the predictive process that uses efference copy signals to attenuate predictable sensory input. A possible explanation for the effect is that TBS has a differential effect on the populations of neurones that generate motor output in M1 than on those neural structures that are involved in generating an efference copy of the motor command. PMID:17560617

  6. A model of TMS-induced I-waves in motor cortex.

    Science.gov (United States)

    Rusu, Cătălin V; Murakami, Max; Ziemann, Ulf; Triesch, Jochen

    2014-01-01

    Transcranial magnetic stimulation (TMS) allows to manipulate neural activity non-invasively, and much research is trying to exploit this ability in clinical and basic research settings. In a standard TMS paradigm, single-pulse stimulation over motor cortex produces repetitive responses in descending motor pathways called I-waves. However, the details of how TMS induces neural activity patterns in cortical circuits to produce these responses remain poorly understood. According to a traditional view, I-waves are due to repetitive synaptic inputs to pyramidal neurons in layer 5 (L5) of motor cortex, but the potential origin of such repetitive inputs is unclear. Here we aim to test the plausibility of an alternative mechanism behind D- and I-wave generation through computational modeling. This mechanism relies on the broad distribution of conduction delays of synaptic inputs arriving at different parts of L5 cells' dendritic trees and their spike generation mechanism. Our model consists of a detailed L5 pyramidal cell and a population of layer 2 and 3 (L2/3) neurons projecting onto it with synapses exhibiting short-term depression. I-waves are simulated as superpositions of spike trains from a large population of L5 cells. Our model successfully reproduces all basic characteristics of I-waves observed in epidural responses during in vivo recordings of conscious humans. In addition, it shows how the complex morphology of L5 neurons might play an important role in the generation of I-waves. In the model, later I-waves are formed due to inputs to distal synapses, while earlier ones are driven by synapses closer to the soma. Finally, the model offers an explanation for the inhibition and facilitation effects in paired-pulse stimulation protocols. In contrast to previous models, which required either neural oscillators or chains of inhibitory interneurons acting upon L5 cells, our model is fully feed-forward without lateral connections or loops. It parsimoniously explains

  7. Primary motor cortex activity reduction under the regulation of SMA by real-time fMRI

    Science.gov (United States)

    Guo, Jia; Zhao, Xiaojie; Li, Yi; Yao, Li; Chen, Kewei

    2012-03-01

    Real-time fMRI (rtfMRI) is a new technology which allows human subjects to observe and control their own BOLD signal change from one or more localized brain regions during scanning. Current rtfMRI-neurofeedback studies mainly focused on the target region itself without considering other related regions influenced by the real-time feedback. However, there always exits important directional influence between many of cooperative regions. On the other hand, rtfMRI based on motor imagery mainly aimed at somatomotor cortex or primary motor area, whereas supplement motor area (SMA) was a relatively more integrated and pivotal region. In this study, we investigated whether the activities of SMA can be controlled utilizing different motor imagery strategies, and whether there exists any possible impact on an unregulated but related region, primary motor cortex (M1). SMA was first localized using overt finger tapping task, the activities of SMA were feedback to subjects visually on line during each of two subsequent imagery motor movement sessions. All thirteen healthy participants were found to be able to successfully control their SMA activities by self-fit imagery strategies which involved no actual motor movements. The activation of right M1 was also found to be significantly reduced in both intensity and extent with the neurofeedback process targeted at SMA, suggestive that not only the part of motor cortex activities were influenced under the regulation of a key region SMA, but also the increased difference between SMA and M1 might reflect the potential learning effect.

  8. Coupling brain-machine interfaces with cortical stimulation for brain-state dependent stimulation: enhancing motor cortex excitability for neurorehabilitation

    Directory of Open Access Journals (Sweden)

    Alireza eGharabaghi

    2014-03-01

    Full Text Available Motor recovery after stroke is an unsolved challenge despite intensive rehabilitation training programs. Brain stimulation techniques have been explored in addition to traditional rehabilitation training to increase the excitability of the stimulated motor cortex. This modulation of cortical excitability augments the response to afferent input during motor exercises, thereby enhancing skilled motor learning by long-term potentiation-like plasticity. Recent approaches examined brain stimulation applied concurrently with voluntary movements to induce more specific use-dependent neural plasticity during motor training for neurorehabilitation. Unfortunately, such approaches are not applicable for the many severely affected stroke patients lacking residual hand function. These patients require novel activity-dependent stimulation paradigms based on intrinsic brain activity. Here, we report on such brain state-dependent stimulation (BSDS combined with haptic feedback provided by a robotic hand orthosis. Transcranial magnetic stimulation of the motor cortex and haptic feedback to the hand were controlled by sensorimotor desynchronization during motor-imagery and applied within a brain-machine interface environment in one healthy subject and one patient with severe hand paresis in the chronic phase after stroke. BSDS significantly increased the excitability of the stimulated motor cortex in both healthy and post-stroke conditions, an effect not observed in non-BSDS protocols. This feasibility study suggests that closing the loop between intrinsic brain state, cortical stimulation and haptic feedback provides a novel neurorehabilitation strategy for stroke patients lacking residual hand function, a proposal that warrants further investigation in a larger cohort of stroke patients.

  9. COMMUNICATION: On variability and use of rat primary motor cortex responses in behavioral task discrimination

    Science.gov (United States)

    Jensen, Winnie; Rousche, Patrick J.

    2006-03-01

    The success of a cortical motor neuroprosthetic system will rely on the system's ability to effectively execute complex motor tasks in a changing environment. Invasive, intra-cortical electrodes have been successfully used to predict joint movement and grip force of a robotic arm/hand with a non-human primate (Chapin J K, Moxon K A, Markowitz R S and Nicolelis M A L 1999 Real-time control of a robotic arm using simultaneously recorded neurons in the motor cortex Nat. Neurosci. 2 664-70). It is well known that cortical encoding occurs with a high degree of cortical plasticity and depends on both the functional and behavioral context. Questions on the expected robustness of future motor prosthesis systems therefore still remain. The objective of the present work was to study the effect of minor changes in functional movement strategies on the M1 encoding. We compared the M1 encoding in freely moving, non-constrained animals that performed two similar behavioral tasks with the same end-goal, and investigated if these behavioral tasks could be discriminated based on the M1 recordings. The rats depressed a response paddle either with a set of restrictive bars ('WB') or without the bars ('WOB') placed in front of the paddle. The WB task required changes in the motor strategy to complete the paddle press and resulted in highly stereotyped movements, whereas in the WOB task the movement strategy was not restricted. Neural population activity was recorded from 16-channel micro-wire arrays and data up to 200 ms before a paddle hit were analyzed off-line. The analysis showed a significant neural firing difference between the two similar WB and WOB tasks, and using principal component analysis it was possible to distinguish between the two tasks with a best classification at 76.6%. While the results are dependent upon a small, randomly sampled neural population, they indicate that information about similar behavioral tasks may be extracted from M1 based on relatively few

  10. Repetitive bilateral arm training with rhythmic auditory cueing improves motor function in chronic hemiparetic stroke

    National Research Council Canada - National Science Library

    Whitall, J; McCombe Waller, S; Silver, K H; Macko, R F

    2000-01-01

    ...) will improve motor function in the hemiparetic arm of stroke patients. In this single group pilot study we determined the effects of 6 weeks of BATRAC on 14 patients with chronic hemiparetic stroke...

  11. Interhemispheric inhibition in distal and proximal arm representations in the primary motor cortex.

    Science.gov (United States)

    Harris-Love, Michelle L; Perez, Monica A; Chen, Robert; Cohen, Leonardo G

    2007-03-01

    Interhemispheric inhibitory interactions (IHI) operate between homologous distal hand representations in primary motor cortex (M1). It is not known whether proximal arm representations exhibit comparable effects on their homologous counterparts. We studied IHI in different arm representations, targeting triceps brachii (TB, n = 13), first dorsal interosseous (FDI, n = 13), and biceps brachii (BB, n = 7) muscles in healthy volunteers. Transcranial magnetic stimulation test stimuli (TS) were delivered to M1 contralateral to the target muscle preceded 10 ms by a conditioning stimulus (CS) to the opposite M1 at 110-150% resting motor threshold (RMT). IHI was calculated as the ratio between motor-evoked potential (MEP) amplitudes in conditioned relative to unconditioned trials. Mean RMTs were 38.9, 46.9, and 46.0% of stimulator output in FDI, TB, and BB muscles, respectively. IHI was 0.45 +/- 0.41 (FDI), 0.78 +/- 0.38 (TB), and 0.52 +/- 0.32 (BB, P FDI) and 0.85 +/- 0.31 (TB, P FDI, 60 s for TB, and 40 s for BB. Additionally, a CS of roughly 120% RMT suppressed the test MEP but not a test H-reflex in BB, suggesting IHI observed in BB is likely mediated by a supraspinal mechanism. We conclude that IHI differs between different arm muscle representations, comparable between BB and FDI but lesser for TB. This finding suggests the amount of IHI between different arm representations does not strictly follow a proximal-to-distal gradient, but may be related to the role of each muscle in functional movement synergies.

  12. Modulation dynamics in the orofacial sensorimotor cortex during motor skill acquisition.

    Science.gov (United States)

    Arce-McShane, Fritzie I; Hatsopoulos, Nicholas G; Lee, Jye-Chang; Ross, Callum F; Sessle, Barry J

    2014-04-23

    The orofacial sensorimotor cortex is known to play a role in motor learning. However, how motor learning changes the dynamics of neuronal activity and whether these changes differ between orofacial primary motor (MIo) and somatosensory (SIo) cortices remain unknown. To address these questions, we used chronically implanted microelectrode arrays to track learning-induced changes in the activity of simultaneously recorded neurons in MIo and SIo as two naive monkeys (Macaca mulatta) were trained in a novel tongue-protrusion task. Over a period of 8-12 d, the monkeys showed behavioral improvements in task performance that were accompanied by rapid and long-lasting changes in neuronal responses in MIo and SIo occurring in parallel: (1) increases in the proportion of task-modulated neurons, (2) increases in the mutual information between tongue-protrusive force and spiking activity, (3) reductions in the across-trial firing rate variability, and (4) transient increases in coherent firing of neuronal pairs. More importantly, the time-resolved mutual information in MIo and SIo exhibited temporal alignment. While showing parallel changes, MIo neurons exhibited a bimodal distribution of peak correlation lag times between spiking activity and force, whereas SIo neurons showed a unimodal distribution. Moreover, coherent activity between pairs of MIo neurons was higher and centered around force onset compared with pairwise coherence of SIo neurons. Overall, the results suggest that the neuroplasticity in MIo and SIo occurring in parallel serves as a substrate for linking sensation and movement during sensorimotor learning, whereas the differing dynamic organizations reflect specific ways to control movement parameters as learning progresses.

  13. Hypoactivation of the primary sensorimotor cortex in de novo Parkinson's disease. A motor fMRI study under controlled conditions

    Energy Technology Data Exchange (ETDEWEB)

    Tessa, Carlo; Vignali, Claudio [Versilia Hospital, AUSL Versilia, Division of Radiology, Camaiore (Italy); Lucetti, Claudio [Versilia Hospital, AUSL Versilia, Division of Neurology, Camaiore (Italy); Diciotti, Stefano; Paoli, Lorenzo; Ginestroni, Andrea; Mascalchi, Mario [University of Florence, Radiodiagnostic Section, Department of Clinical Physiopathology, Florence (Italy); Cecchi, Paolo; Baldacci, Filippo [University of Pisa, Department of Neuroscience, Pisa (Italy); Giannelli, Marco [Azienda Ospedaliero-Universitaria Pisana, Unit of Medical Physics, Pisa (Italy); Bonuccelli, Ubaldo [Versilia Hospital, AUSL Versilia, Division of Neurology, Camaiore (Italy); University of Pisa, Department of Neuroscience, Pisa (Italy)

    2012-03-15

    Nuclear medicine studies in Parkinson's disease (PD) indicate that nigrostriatal damage causes a widespread cortical hypoactivity assumed to be due to reduced excitatory thalamic outflow. However, so far, functional MRI (fMRI) studies have provided controversial data about this ''functional deafferentation'' phenomenon. To further clarify this issue, we assessed, with fMRI, de novo drug-naive PD patients using a relatively complex motor task under strictly controlled conditions. Nineteen de novo PD patients with right-predominant or bilateral symptoms and 13 age-matched healthy volunteers performed continuous writing of ''8'' figures with the right-dominant hand using a MR-compatible device that enables identification of incorrectly performed tasks and measures the size and the frequency of the ''8''s. The data were analyzed with FSL software and correlated with the clinical severity rated according to the Hoehn and Yahr (HY) staging system. Fifteen (89%) of 19 PD patients and 12 (92%) of 13 controls correctly executed the task. PD patients showed significant hypoactivation of the left primary sensorimotor cortex (SM1) and cerebellum and no hyperactive areas as compared to controls. However, activation in SM1 and supplementary motor area bilaterally, in left supramarginal, parietal inferior, parietal superior and frontal superior gyri as well as in right parietal superior and angular gyri paralleled increasing disease severity as assessed with the HY stage. In line with the ''deafferentation hypothesis'', fMRI demonstrates hypoactivation of the SM1 in the early clinical stage of PD. (orig.)

  14. Efficacy and interindividual variability in motor-cortex plasticity following anodal tDCS and paired-associative stimulation.

    Science.gov (United States)

    Strube, Wolfgang; Bunse, Tilmann; Malchow, Berend; Hasan, Alkomiet

    2015-01-01

    Interindividual response variability to various motor-cortex stimulation protocols has been recently reported. Comparative data of stimulation protocols with different modes of action is lacking. We aimed to compare the efficacy and response variability of two LTP-inducing stimulation protocols in the human motor cortex: anodal transcranial direct current stimulation (a-tDCS) and paired-associative stimulation (PAS25). In two experiments 30 subjects received 1mA a-tDCS and PAS25. Data analysis focused on motor-cortex excitability change and response defined as increase in MEP applying different cut-offs. Furthermore, the predictive pattern of baseline characteristics was explored. Both protocols induced a significant increase in motor-cortical excitability. In the PAS25 experiments the likelihood to develop a MEP response was higher compared to a-tDCS, whereas for intracortical facilitation (ICF) the likelihood for a response was higher in the a-tDCS experiments. Baseline ICF (12 ms) correlated positively with an increase in MEPs only following a-tDCS and responders had significantly higher ICF baseline values. Contrary to recent studies, we showed significant group-level efficacy following both stimulation protocols confirming older studies. However, we also observed a remarkable amount of nonresponders. Our findings highlight the need to define sufficient physiological read-outs for a given plasticity protocol and to develop predictive markers for targeted stimulation.

  15. Bilateral deficits in fine motor control and pinch grip force are not associated with electrodiagnostic findings in women with carpal tunnel syndrome.

    Science.gov (United States)

    de la Llave-Rincón, Ana Isabel; Fernández-de-Las-Peñas, César; Pérez-de-Heredia-Torres, Marta; Martínez-Perez, Almudena; Valenza, Marie Carmen; Pareja, Juan A

    2011-06-01

    : The aim of this study was to analyze the differences in deficits in fine motor control and pinch grip force between patients with minimal, moderate/mild, or severe carpal tunnel syndrome (CTS) and healthy age- and hand dominance-matched controls. : A case-control study was conducted. The subtests of the Purdue Pegboard Test (one-hand and bilateral pin placements and assemblies) and pinch grip force between the thumb and the remaining four fingers of the hand were bilaterally evaluated in 66 women with minimal (n = 16), moderate (n = 16), or severe (n = 34) CTS and in 20 age- and hand-matched healthy women. The differences among the groups were analyzed using different mixed models of analysis of variance. : A two-way mixed analysis of variance revealed significant differences between groups, not depending on the presence of unilateral or bilateral symptoms (side), for the one-hand pin placement subtest: patients showed bilateral lower scores compared with controls (P < 0.001), without differences among those with minimal, moderate, or severe CTS (P = 0.946). The patients also exhibited lower scores in bilateral pin placement (P < 0.001) and assembly (P < 0.001) subtests, without differences among them. The three-way analysis of variance revealed significant differences among groups (P < 0.001) and fingers (P < 0.001), not depending on the presence of unilateral/bilateral symptoms (P = 0.684), for pinch grip force: patients showed bilateral lower pinch grip force in all fingers compared with healthy controls, without differences among those with minimal, moderate, or severe CTS. : The current study revealed similar bilateral deficits in fine motor control and pinch grip force in patients with minimal, moderate, or severe CTS, supporting that fine motor control deficits are a common feature of CTS not associated with electrodiagnostic findings.

  16. Diffusion tensor imaging detects early cerebral cortex abnormalities in neuronal architecture induced by bilateral neonatal enucleation: An experimental model in the ferret

    Directory of Open Access Journals (Sweden)

    Andrew S Bock

    2010-10-01

    Full Text Available Diffusion tensor imaging (DTI is a technique that non-invasively provides quantitative measures of water translational diffusion, including fractional anisotropy (FA, that are sensitive to the shape and orientation of cellular elements, such as axons, dendrites and cell somas. For several neurodevelopmental disorders, histopathological investigations have identified abnormalities in the architecture of pyramidal neurons at early stages of cerebral cortex development. To assess the potential capability of DTI to detect neuromorphological abnormalities within the developing cerebral cortex, we compare changes in cortical FA with changes in neuronal architecture and connectivity induced by bilateral enucleation at postnatal day 7 (BEP7 in ferrets. We show here that the visual callosal pattern in BEP7 ferrets is more irregular and occupies a significantly greater cortical area compared to controls at adulthood. To determine whether development of the cerebral cortex is altered in BEP7 ferrets in a manner detectable by DTI, cortical FA was compared in control and BEP7 animals on postnatal day 31. Visual cortex, but not rostrally-adjacent non-visual cortex, exhibits higher FA than control animals, consistent with BEP7 animals possessing axonal and dendritic arbors of reduced complexity than age-matched controls. Subsequent to DTI, Golgi staining and analysis methods were used to identify regions, restricted to visual areas, in which the orientation distribution of neuronal processes is significantly more concentrated than in control ferrets. Together, these findings suggest that DTI can be of utility for detecting abnormalities associated with neurodevelopmental disorders at early stages of cerebral cortical development, and that the neonatally-enucleated ferret is a useful animal model system for systematically assessing the potential of this new diagnostic strategy.

  17. Role of the cerebellum and motor cortex in the regulation of visually controlled locomotion.

    Science.gov (United States)

    Armstrong, D M; Marple-Horvat, D E

    1996-04-01

    An account is given of the current state of knowledge of the contributions of the cerebellum and the forelimb motor cortex (MC) to the neural control of walking movements in the cat. The main emphasis is on information obtained by recording from single MC and cerebellar neurones in chronically instrumented cats engaged in walking on the rungs of a horizontal ladder, a form of locomotion that is heavily dependent on visual input and for which the integrity of MC is essential. Evidence from the authors' laboratory and from other studies is presented which establishes that MC neurones, including pyramidal tract neurones, show higher levels of activity during ladder walking than during overground walking (i.e., when less constraint exists over the locus of footfall) and that this increase is greatest in late swing-early stance in the contralateral forelimb, consistent with one role of MC being to help determine the locus of footfall. However, many MC neurones develop peak activity at other times in the step cycle, and a comparison with recordings during treadmill walking suggests MC may also help regulate stance duration when walking speed is an important performance variable. Recordings from Purkinje cells and cerebellar nuclear neurones show that during ladder walking step-related activity is widespread in the vermal, paravermal, and crural regions of cortex and in the interposed and dentate nuclei. Nuclear cell activity is so timed that it could be contributing to producing the locomotor rhythms evident in MC cells, although this is not yet proven. Results are also presented and discussed relating to MC and cerebellar neuronal responses that occur when a step onto an unstable rung results in an unexpected external perturbation of the forelimb step cycle. MC responses begin with onset latency as short as 20 ms so that MC may assist spinal reflex mechanisms to produce a post hoc compensatory change in motor output. However, work in progress suggests that corresponding

  18. Sentential context modulates the involvement of the motor cortex in action language processing: An fMRI study

    Directory of Open Access Journals (Sweden)

    Karen D.I. Schuil

    2013-04-01

    Full Text Available Theories of embodied cognition propose that language comprehension is based on perceptual and motor processes. More specifically, it is hypothesized that neurons processing verbs describing bodily actions, and those that process the corresponding physical actions, fire simultaneously during action verb learning. Thus the concept and motor activation become strongly linked. According to this view, the language-induced activation of the neural substrates for action is automatic. By contrast, a moderate view of embodied cognition proposes that activation of these motor regions is modulated by context. In recent studies it was found that action verbs in literal sentences activate the motor system, while mixed results were observed for action verbs in nonliteral sentences. Thus, whether the recruitment of motor regions is automatic or context dependent remains a question. We investigated functional magnetic resonance imaging activation in response to nonliteral and literal sentences including arm and leg related actions. The sentence structure was such that the action verb was the last word in the subordinate clause. Thus, the constraining context was presented well before the verb. Region of interest analyses showed that action verbs in literal context engage the motor regions to a greater extent than nonliteral action verbs. There was no evidence for a semantic somatotopic organization of the motor cortex. Taken together, these results indicate that during comprehension, the degree to which motor regions are recruited is context dependent, supporting the weak view of embodied cognition.

  19. Homeostatic plasticity in human motor cortex demonstrated by two consecutive sessions of paired associative stimulation.

    Science.gov (United States)

    Müller, J Florian M; Orekhov, Yuriy; Liu, Yali; Ziemann, Ulf

    2007-06-01

    Long-term potentiation (LTP) and long-term depression (LTD) underlie most models of learning and memory, but neural activity would grow or shrink in an uncontrolled manner, if not guarded by stabilizing mechanisms. The Bienenstock-Cooper-Munro (BCM) rule proposes a sliding threshold for LTP/LTD induction: LTP induction becomes more difficult if neural activity was high previously. Here we tested if this form of homeostatic plasticity applies to the human motor cortex (M1) in vivo by examining the interactions between two consecutive sessions of paired associative stimulation (PAS). PAS consisted of repeated pairs of electrical stimulation of the right median nerve followed by transcranial magnetic stimulation of the left M1. The first PAS session employed an interstimulus interval equalling the individual N20-latency of the median nerve somatosensory-evoked cortical potential plus 2 ms, N20-latency minus 5 ms, or a random alternation between these intervals, to induce an LTP-like increase in motor-evoked potential (MEP) amplitudes in the right abductor pollicis brevis muscle (PAS(LTP)), an LTD-like decrease (PAS(LTD)), or no change (PAS(Control)), respectively. The second PAS session 30 min later was always PAS(LTP). It induced an moderate LTP-like effect if conditioned by PAS(Control), which increased if conditioned by PAS(LTD), but decreased if conditioned by PAS(LTP). Effects on MEP amplitude induced by the second PAS session exhibited a negative linear correlation with those in the first PAS session. Because the two PAS sessions activate identical neuronal circuits, we conclude that 'homosynaptic-like' homeostatic mechanisms in accord with the BCM rule contribute to regulating plasticity in human M1.

  20. Direction of movement is encoded in the human primary motor cortex.

    Directory of Open Access Journals (Sweden)

    Carolien M Toxopeus

    Full Text Available The present study investigated how direction of hand movement, which is a well-described parameter in cerebral organization of motor control, is incorporated in the somatotopic representation of the manual effector system in the human primary motor cortex (M1. Using functional magnetic resonance imaging (fMRI and a manual step-tracking task we found that activation patterns related to movement in different directions were spatially disjoint within the representation area of the hand on M1. Foci of activation related to specific movement directions were segregated within the M1 hand area; activation related to direction 0° (right was located most laterally/superficially, whereas directions 180° (left and 270° (down elicited activation more medially within the hand area. Activation related to direction 90° was located between the other directions. Moreover, by investigating differences between activations related to movement along the horizontal (0°+180° and vertical (90°+270° axis, we found that activation related to the horizontal axis was located more anterolaterally/dorsally in M1 than for the vertical axis, supporting that activations related to individual movement directions are direction- and not muscle related. Our results of spatially segregated direction-related activations in M1 are in accordance with findings of recent fMRI studies on neural encoding of direction in human M1. Our results thus provide further evidence for a direct link between direction as an organizational principle in sensorimotor transformation and movement execution coded by effector representations in M1.

  1. Characterization of torque-related activity in primary motor cortex during a multijoint postural task.

    Science.gov (United States)

    Herter, Troy M; Kurtzer, Isaac; Cabel, D William; Haunts, Kirk A; Scott, Stephen H

    2007-04-01

    The present study examined neural activity in the shoulder/elbow region of primary motor cortex (M1) during a whole-limb postural task. By selectively imposing torques at the shoulder, elbow, or both joints we addressed how neurons represent changes in torque at a single joint, multiple joints, and their interrelation. We observed that similar proportions of neurons reflected changes in torque at the shoulder, elbow, and both joints and these neurons were highly intermingled across the cortical surface. Most torque-related neurons were reciprocally excited and inhibited (relative to their unloaded baseline activity) by opposing flexor and extensor torques at a single joint. Although coexcitation/coinhibition was occasionally observed at a single joint, it was rarely observed at both joints. A second analysis assessed the relationship between single-joint and multijoint activity. In contrast to our previous observations, we found that neither linear nor vector summation of single-joint activities could capture the breadth of neural responses to multijoint torques. Finally, we studied the neurons' directional tuning across all the torque conditions, i.e., in joint-torque space. Our population of M1 neurons exhibited a strong bimodal distribution of preferred-torque directions (PTDs) that was biased toward shoulder-extensor/elbow-flexor (whole-limb flexor) and shoulder-flexor/elbow-extensor (whole-limb extensor) torques. Notably, we recently observed a similar bimodal distribution of PTDs in a sample of proximal arm muscles. This observation illustrates the intimate relationship between M1 and the motor periphery.

  2. Neuroplastic effects of transcranial near-infrared stimulation (tNIRS on the motor cortex

    Directory of Open Access Journals (Sweden)

    Leila eChaieb

    2015-06-01

    Full Text Available Near-infrared light stimulation of the brain has been claimed to improve deficits caused by traumatic brain injury and stroke. Here, we exploit the effect of transcranial near-infrared stimulation (tNIRS as a tool to modulate cortical excitability in the healthy human brain. tNIRS was applied at a wavelength of 810 nm for 10 minutes over the hand area of the primary motor cortex (M1. Both single-pulse and paired-pulse measures of transcranial magnetic stimulation (TMS were used to assess levels of cortical excitability in the corticospinal pathway and intracortical circuits. The serial reaction time task (SRTT was used to investigate the possible effect of tNIRS on implicit learning.By evaluating the mean amplitude of single-pulse TMS elicited motor-evoked-potentials (MEPs a significant decrease of the amplitude was observed up to 30 minutes post-stimulation, compared to baseline. Furthermore, the short interval cortical inhibition (SICI was increased and facilitation (ICF decreased significantly after tNIRS. The results from the SRTT experiment show that there was no net effect of stimulation on the performance of the participants. Results of a study questionnaire demonstrated that tNIRS did not induce serious side effects apart from light headache and fatigue. Nevertheless, 66% were able to detect the difference between active and sham stimulation conditions.In this study we provide further evidence that tNIRS is suitable as a tool for influencing cortical excitability and activity in the healthy human brain.

  3. Effect of serotonin on paired associative stimulation-induced plasticity in the human motor cortex.

    Science.gov (United States)

    Batsikadze, Giorgi; Paulus, Walter; Kuo, Min-Fang; Nitsche, Michael A

    2013-10-01

    Serotonin modulates diverse brain functions. Beyond its clinical antidepressant effects, it improves motor performance, learning and memory formation. These effects might at least be partially caused by the impact of serotonin on neuroplasticity, which is thought to be an important foundation of the respective functions. In principal accordance, selective serotonin reuptake inhibitors enhance long-term potentiation-like plasticity induced by transcranial direct current stimulation (tDCS) in humans. As other neuromodulators have discernable effects on different kinds of plasticity in humans, here we were interested to explore the impact of serotonin on paired associative stimulation (PAS)-induced plasticity, which induces a more focal kind of plasticity, as compared with tDCS, shares some features with spike timing-dependent plasticity, and is thought to be relative closely related to learning processes. In this single-blinded, placebo-controlled, randomized crossover study, we administered a single dose of 20 mg citalopram or placebo medication and applied facilitatory- and excitability-diminishing PAS to the left motor cortex of 14 healthy subjects. Cortico-spinal excitability was explored via single-pulse transcranial magnetic stimulation-elicited MEP amplitudes up to the next evening after plasticity induction. After citalopram administration, inhibitory PAS-induced after-effects were abolished and excitatory PAS-induced after-effects were enhanced trendwise, as compared with the respective placebo conditions. These results show that serotonin modulates PAS-induced neuroplasticity by shifting it into the direction of facilitation, which might help to explain mechanism of positive therapeutic effects of serotonin in learning and medical conditions characterized by enhanced inhibitory or reduced facilitatory plasticity, including depression and stroke.

  4. Abnormal motor cortex excitability during linguistic tasks in adductor-type spasmodic dysphonia.

    Science.gov (United States)

    Suppa, A; Marsili, L; Giovannelli, F; Di Stasio, F; Rocchi, L; Upadhyay, N; Ruoppolo, G; Cincotta, M; Berardelli, A

    2015-08-01

    In healthy subjects (HS), transcranial magnetic stimulation (TMS) applied during 'linguistic' tasks discloses excitability changes in the dominant hemisphere primary motor cortex (M1). We investigated 'linguistic' task-related cortical excitability modulation in patients with adductor-type spasmodic dysphonia (ASD), a speech-related focal dystonia. We studied 10 ASD patients and 10 HS. Speech examination included voice cepstral analysis. We investigated the dominant/non-dominant M1 excitability at baseline, during 'linguistic' (reading aloud/silent reading/producing simple phonation) and 'non-linguistic' tasks (looking at non-letter strings/producing oral movements). Motor evoked potentials (MEPs) were recorded from the contralateral hand muscles. We measured the cortical silent period (CSP) length and tested MEPs in HS and patients performing the 'linguistic' tasks with different voice intensities. We also examined MEPs in HS and ASD during hand-related 'action-verb' observation. Patients were studied under and not-under botulinum neurotoxin-type A (BoNT-A). In HS, TMS over the dominant M1 elicited larger MEPs during 'reading aloud' than during the other 'linguistic'/'non-linguistic' tasks. Conversely, in ASD, TMS over the dominant M1 elicited increased-amplitude MEPs during 'reading aloud' and 'syllabic phonation' tasks. CSP length was shorter in ASD than in HS and remained unchanged in both groups performing 'linguistic'/'non-linguistic' tasks. In HS and ASD, 'linguistic' task-related excitability changes were present regardless of the different voice intensities. During hand-related 'action-verb' observation, MEPs decreased in HS, whereas in ASD they increased. In ASD, BoNT-A improved speech, as demonstrated by cepstral analysis and restored the TMS abnormalities. ASD reflects dominant hemisphere excitability changes related to 'linguistic' tasks; BoNT-A returns these excitability changes to normal.

  5. Asymmetric activation of the primary motor cortex during observation of a mirror reflection of a hand.

    Directory of Open Access Journals (Sweden)

    Wataru Tominaga

    Full Text Available Mirror therapy is an effective technique for pain relief and motor function recovery. It has been demonstrated that magnetic 20-Hz activity is induced in the primary motor cortex (M1 after median nerve stimulation and that the amount of the stimulus-induced 20-Hz activity is decreased when the M1 is activated. In the present study, we investigated how the image or the mirror reflection of a hand holding a pencil modulates the stimulus-induced 20-Hz activity in the M1. Neuromagnetic brain activity was recorded from 13 healthy right-handed subjects while they were either viewing directly their hand holding a pencil or viewing a mirror reflection of their hand holding a pencil. The 20-Hz activity in the left or the right M1 was examined after the right or the left median nerve stimulation, respectively, and the suppression of the stimulus-induced 20-Hz in the M1 by viewing directly one hand holding a pencil or by viewing the mirror image of the hand holding a pencil was assumed to indicate the activation of the M1. The results indicated that the M1 innervating the dominant hand was suppressed either by viewing directly the dominant hand holding a pencil or by viewing the mirror image of the non-dominant hand holding a pencil. On the other hand, the M1 innervating the non-dominant hand was activated by viewing the mirror image of the dominant hand holding a pencil, but was not activated by viewing directly the non-dominant hand holding a pencil. The M1 innervating either the dominant or the non-dominant hand, however, was not activated by viewing the hand on the side ipsilateral to the M1 examined or the mirror image of the hand on the side contralateral to the M1 exaimined. Such activation of the M1 might induce some therapeutic effects of mirror therapy.

  6. The Mirror Illusion Increases Motor Cortex Excitability in Children With and Without Hemiparesis.

    Science.gov (United States)

    Grunt, Sebastian; Newman, Christopher J; Saxer, Stefanie; Steinlin, Maja; Weisstanner, Christian; Kaelin-Lang, Alain

    2017-03-01

    Mirror therapy provides a visual illusion of a normal moving limb by using the mirror reflection of the unaffected arm instead of viewing the paretic limb and is used in rehabilitation to improve hand function. Little is known about the mechanism underlying its effect in children with hemiparesis. To investigate the effect of the mirror illusion (MI) on the excitability of the primary motor cortex (M1) in children and adolescents. Twelve patients with hemiparesis (10-20 years) and 8 typically developing subjects (8-17 years) participated. Corticospinal reorganization was classified as contralateral (projection from contralateral hemisphere to affected hand) or ipsilateral (projection from ipsilateral hemisphere to affected hand). M1 excitability of the hemisphere projecting to the affected (nondominant in typically developing subjects) hand was obtained during 2 different conditions using single-pulse transcranial magnetic stimulation (TMS). Each condition (without/with mirror) consisted of a unimanual and a bimanual task. Motor-evoked potentials (MEPs) were recorded from the abductor pollicis brevis and flexor digitorum superficialis muscles. MEP amplitudes were significantly increased during the mirror condition ( P = .005) in typically developing subjects and in patients with contralateral reorganization. No significant effect of MI was found in subjects with ipsilateral reorganization. MI increased M1 excitability during active movements only. This increase was not correlated to hand function. MI increases the excitability of M1 in hemiparetic patients with contralateral corticospinal organization and in typically developing subjects. This finding provides neurophysiological evidence supporting the application of mirror therapy in selected children and adolescents with hemiparesis.

  7. Dopamine control of pyramidal neuron activity in the primary motor cortex via D2 receptors

    Directory of Open Access Journals (Sweden)

    Clément eVitrac

    2014-02-01

    Full Text Available The primary motor cortex (M1 is involved in fine voluntary movements control. Previous studies have shown the existence of a dopamine (DA innervation in M1 of rats and monkeys that could directly modulate M1 neuronal activity. However, none of these studies have described the precise distribution of DA terminals within M1 functional region nor have quantified the density of this innervation. Moreover, the precise role of DA on pyramidal neuron activity still remains unclear due to conflicting results from previous studies regarding D2 effects on M1 pyramidal neurons.In this study we assessed in mice the neuroanatomical characteristics of DA innervation in M1 using unbiased stereological quantification of dopamine transporter-immunostained fibers. We demonstrated for the first time in mice that DA innervates the deep layers of M1 targeting preferentially the forelimb representation area of M1. To address the functional role of the DA innervation on M1 neuronal activity, we performed electrophysiological recordings of single neurons activity in vivo and pharmacologically modulated D2 receptors activity. Local D2 receptors activation by quinpirole enhanced pyramidal neurons spike firing rate without changes in spike firing pattern. Altogether, these results indicate that DA innervation in M1 can increase neuronal activity through D2 receptors activation and suggest a potential contribution to the modulation of fine forelimb movement. Given the demonstrated role for DA in fine motor skill learning in M1, our results suggest that altered D2 modulation of M1 activity may be involved in the pathophysiology of movement disorders associated with disturbed DA homeostasis.

  8. Two distinct interneuron circuits in human motor cortex are linked to different subsets of physiological and behavioral plasticity.

    Science.gov (United States)

    Hamada, Masashi; Galea, Joseph M; Di Lazzaro, Vincenzo; Mazzone, Paolo; Ziemann, Ulf; Rothwell, John C

    2014-09-17

    How does a single brain region participate in multiple behaviors? Here we argue that two separate interneuron circuits in the primary motor cortex (M1) contribute differently to two varieties of physiological and behavioral plasticity. To test this in human brain noninvasively, we used transcranial magnetic stimulation (TMS) of M1 hand area to activate two independent sets of synaptic inputs to corticospinal neurons by changing the direction of current induced in the brain: posterior-to-anterior current (PA inputs) and anterior-to-posterior current (AP inputs). We demonstrate that excitability changes produced by repetitive activation of AP inputs depend on cerebellar activity and selectively alter model-based motor learning. In contrast, the changes observed with repetitive stimulation of PA inputs are independent of cerebellar activity and specifically modulate model-free motor learning. The findings are highly suggestive that separate circuits in M1 subserve different forms of motor learning.

  9. Somatotopic reorganization of hand representation in bilateral arm amputees with or without special foot movement skill.

    Science.gov (United States)

    Yu, Xiao Jing; He, Hong Jian; Zhang, Qiao Wei; Zhao, Feng; Zee, Chi Shing; Zhang, Shi Zheng; Gong, Xiang Yang

    2014-02-10

    Bilateral arm amputees usually are excellent foot users. To explore the plasticity of the primary motor cortex in upper-extremities amputees and to determine if the acquisition of special foot movement skill is related with the bilateral hand amputation, we studied the primary motor cortex by using combined task and resting state functional magnetic resonance imaging (fMRI). We investigated 6 bilateral arm amputees with or without special foot movement skill. In the task fMRI study, we found that toe tapping of all the amputees activated the bilateral hand area, including cases without special foot skill. In addition, cases without special foot skill mainly activated the precentral gyrus, which differed from those with more adept foot motor skill who activated both the precentral and postcentral gyri. To further understand the plasticity of the hand area, the resting state functional connectivity was investigated between the foot and hand regions. One-tailed two-sample t-test suggested that the connections between two areas became significantly stronger in the amputee group. Our study demonstrates that hand region of the cortex does not remain 'silent' after bilateral arm amputation, but rather is recruited by other modalities such as adjacent or nonadjacent cortexes to process motor information in a functionally relevant manner. From the data presented, it seems that the bilateral arm amputees have a strong potential to develop new skills in their remaining extremities and practice may further enhance this potential.

  10. Testing the Role of Dorsal Premotor Cortex in Auditory-Motor Association Learning Using Transcranical Magnetic Stimulation (TMS)

    Science.gov (United States)

    Lega, Carlotta; Stephan, Marianne A.; Zatorre, Robert J.; Penhune, Virginia

    2016-01-01

    Interactions between the auditory and the motor systems are critical in music as well as in other domains, such as speech. The premotor cortex, specifically the dorsal premotor cortex (dPMC), seems to play a key role in auditory-motor integration, and in mapping the association between a sound and the movement used to produce it. In the present studies we tested the causal role of the dPMC in learning and applying auditory-motor associations using 1 Hz repetitive Transcranical Magnetic Stimulation (rTMS). In this paradigm, non-musicians learn a set of auditory-motor associations through melody training in two contexts: first when the sound to key-press mapping was in a conventional sequential order (low to high tones mapped onto keys from left to right), and then when it was in a novel scrambled order. Participant’s ability to match the four pitches to four computer keys was tested before and after the training. In both experiments, the group that received 1 Hz rTMS over the dPMC showed no significant improvement on the pitch-matching task following training, whereas the control group (who received rTMS to visual cortex) did. Moreover, in Experiment 2 where the pitch-key mapping was novel, rTMS over the dPMC also interfered with learning. These findings suggest that rTMS over dPMC disturbs the formation of auditory-motor associations, especially when the association is novel and must be learned rather explicitly. The present results contribute to a better understanding of the role of dPMC in auditory-motor integration, suggesting a critical role of dPMC in learning the link between an action and its associated sound. PMID:27684369

  11. Motor training and the combination of action observation and peripheral nerve stimulation reciprocally interfere with the plastic changes induced in primary motor cortex excitability.

    Science.gov (United States)

    Bisio, Ambra; Avanzino, Laura; Biggio, Monica; Ruggeri, Piero; Bove, Marco

    2017-02-15

    AO-PNS is a stimulation protocol combining action observation (AO) and peripheral nerve stimulation (PNS) to induce plasticity in the primary motor cortex (M1) (increased excitability). Another method to increase M1 excitability is motor training. The combination of two protocols, which individually induce long-term potentiation (LTP)-like plasticity in overlapping neural circuits, results in a transitory occlusion or reverse of this phenomenon. This study aimed to understand the neurophysiological mechanisms underlying AO-PNS by testing whether AO-PNS and motor training induced LTP-like plasticity in, at least partially, overlapping neural networks. One group of participants practiced a motor training (finger opposition movements) followed by AO-PNS, whereas another group performed the two protocols in reverse order. Motor performance was evaluated by means of a sensor-engineered glove and transcranial magnetic stimulation was used to assess M1 excitability before and after each conditioning protocol. Motor training increased movement frequency, suggesting the occurrence of motor learning in both groups. When applied on first, both motor training and AO-PNS significantly increased the motor-evoked potential (MEP), but occluded the increase of cortical excitability expected after the following protocol, leading to a significant decrease of MEP amplitude. These results suggest that motor training and AO-PNS act on partially overlapping neuronal networks, which include M1, and that AO-PNS might be able to induce LTP-like plasticity in a similar way to overt movement execution. This candidates AO-PNS as methodology potentially useful when planning rehabilitative interventions on patients who cannot voluntarily move.

  12. Altered Modulation of Silent Period in Tongue Motor Cortex of Persistent Developmental Stuttering in Relation to Stuttering Severity.

    Science.gov (United States)

    Busan, Pierpaolo; Del Ben, Giovanni; Bernardini, Simona; Natarelli, Giulia; Bencich, Marco; Monti, Fabrizio; Manganotti, Paolo; Battaglini, Piero Paolo

    2016-01-01

    Motor balance in developmental stuttering (DS) was investigated with Transcranial Magnetic Stimulation (TMS), with the aim to define novel neural markers of persistent DS in adulthood. Eleven DS adult males were evaluated with TMS on tongue primary motor cortex, compared to 15 matched fluent speakers, in a "state" condition (i.e. stutterers vs. fluent speakers, no overt stuttering). Motor and silent period thresholds (SPT), recruitment curves, and silent period durations were acquired by recording tongue motor evoked potentials. Tongue silent period duration was increased in DS, especially in the left hemisphere (Pstuttering severity. Pre-TMS electromyography data gave overlapping evidence. Findings suggest the existence of a complex intracortical balance in DS tongue primary motor cortex, with a particular interplay between excitatory and inhibitory mechanisms, also in neural substrates related to silent periods. Findings are discussed with respect to functional and structural impairments in stuttering, and are also proposed as novel neural markers of a stuttering "state" in persistent DS, helping to define more focused treatments (e.g. neuro-modulation).

  13. Altered Modulation of Silent Period in Tongue Motor Cortex of Persistent Developmental Stuttering in Relation to Stuttering Severity

    Science.gov (United States)

    Busan, Pierpaolo; Del Ben, Giovanni; Bernardini, Simona; Natarelli, Giulia; Bencich, Marco; Monti, Fabrizio; Manganotti, Paolo; Battaglini, Piero Paolo

    2016-01-01

    Motor balance in developmental stuttering (DS) was investigated with Transcranial Magnetic Stimulation (TMS), with the aim to define novel neural markers of persistent DS in adulthood. Eleven DS adult males were evaluated with TMS on tongue primary motor cortex, compared to 15 matched fluent speakers, in a “state” condition (i.e. stutterers vs. fluent speakers, no overt stuttering). Motor and silent period thresholds (SPT), recruitment curves, and silent period durations were acquired by recording tongue motor evoked potentials. Tongue silent period duration was increased in DS, especially in the left hemisphere (Pstuttering severity. Pre-TMS electromyography data gave overlapping evidence. Findings suggest the existence of a complex intracortical balance in DS tongue primary motor cortex, with a particular interplay between excitatory and inhibitory mechanisms, also in neural substrates related to silent periods. Findings are discussed with respect to functional and structural impairments in stuttering, and are also proposed as novel neural markers of a stuttering “state” in persistent DS, helping to define more focused treatments (e.g. neuro-modulation). PMID:27711148

  14. Afferent-induced facilitation of primary motor cortex excitability in the region controlling hand muscles in humans.

    Science.gov (United States)

    Devanne, H; Degardin, A; Tyvaert, L; Bocquillon, P; Houdayer, E; Manceaux, A; Derambure, P; Cassim, F

    2009-08-01

    Sensory inputs from cutaneous and limb receptors are known to influence motor cortex network excitability. Although most recent studies have focused on the inhibitory influences of afferent inputs on arm motor responses evoked by transcranial magnetic stimulation (TMS), facilitatory effects are rarely considered. In the present work, we sought to establish how proprioceptive sensory inputs modulate the excitability of the primary motor cortex region controlling certain hand and wrist muscles. Suprathreshold TMS pulses were preceded either by median nerve stimulation (MNS) or index finger stimulation with interstimulus intervals (ISIs) ranging from 20 to 200 ms (with particular focus on 40-80 ms). Motor-evoked potentials recorded in the abductor pollicis brevis (APB), first dorsalis interosseus and extensor carpi radialis muscles were strongly facilitated (by up to 150%) by MNS with ISIs of around 60 ms, whereas digit stimulation had only a weak effect. When MNS was delivered at the interval that evoked the optimal facilitatory effect, the H-reflex amplitude remained unchanged and APB motor responses evoked with transcranial electric stimulation were not increased as compared with TMS. Afferent-induced facilitation and short-latency intracortical inhibition (SICI) and intracortical facilitation (ICF) mechanisms are likely to interact in cortical circuits, as suggested by the strong facilitation observed when MNS was delivered concurrently with ICF and the reduction of SICI following MNS. We conclude that afferent-induced facilitation is a mechanism which probably involves muscle spindle afferents and should be considered when studying sensorimotor integration mechanisms in healthy and disease situations.

  15. Primary motor cortex alterations in Alzheimer disease: A study in the 3xTg-AD model.

    Science.gov (United States)

    Orta-Salazar, E; Feria-Velasco, A I; Díaz-Cintra, S

    2017-04-19

    In humans and animal models, Alzheimer disease (AD) is characterised by accumulation of amyloid-β peptide (Aβ) and hyperphosphorylated tau protein, neuronal degeneration, and astrocytic gliosis, especially in vulnerable brain regions (hippocampus and cortex). These alterations are associated with cognitive impairment (loss of memory) and non-cognitive impairment (motor impairment). The purpose of this study was to identify cell changes (neurons and glial cells) and aggregation of Aβ and hyperphosphorylated tau protein in the primary motor cortex (M1) in 3xTg-AD mouse models at an intermediate stage of AD. We used female 3xTg-AD mice aged 11 months and compared them to non-transgenic mice of the same age. In both groups, we assessed motor performance (open field test) and neuronal damage in M1 using specific markers: BAM10 (extracellular Aβ aggregates), tau 499 (hyperphosphorylated tau protein), GFAP (astrocytes), and Klüver-Barrera staining (neurons). Female 3xTg-AD mice in intermediate stages of the disease displayed motor and cellular alterations associated with Aβ and hyperphosphorylated tau protein deposition in M1. Patients with AD display signs and symptoms of functional impairment from early stages. According to our results, M1 cell damage in intermediate-stage AD affects motor function, which is linked to progression of the disease. Copyright © 2017 Sociedad Española de Neurología. Publicado por Elsevier España, S.L.U. All rights reserved.

  16. Motor cortex tDCS does not improve strength performance in healthy subjects

    Directory of Open Access Journals (Sweden)

    Rafael Montenegro

    2015-06-01

    Full Text Available The influence of transcranial direct current stimulation (tDCS upon maximal strength performance in exercises recruiting large muscle mass has not been established in healthy populations. The purpose of this study was to investigate whether anodal tDCS was able to increase the performance during maximal strength exercise (MSEX in healthy subjects. Fourteen volunteers (age: 26 ± 4 yrs performed two MSEX after anodal or sham tDCS (2mA; 20min prior MSEX, involving knee extensors and flexors in concentric isokinetic muscle actions of the dominant limb (3 sets of 10 repetitions. The electrical muscle activity (sEMG of four recruited muscles was recorded during MSEX. Anodal tDCS was not able to improve force production (i.e., total work and peak torque, fatigue resistance, or electromyographic activity during MSEX when compared to sham condition. In conclusion, anodal tDCS applied upon the contralateral motor cortex was not capable of increasing the strength performance of knee extensors and flexors in young healthy subjects.

  17. Motor cortex rTMS improves dexterity in relapsing-remitting and secondary progressive multiple sclerosis.

    Science.gov (United States)

    Elzamarany, Eman; Afifi, Lamia; El-Fayoumy, Neveen M; Salah, Husam; Nada, Mona

    2016-06-01

    The motor cortex (MC) receives an excitatory input from the cerebellum which is reduced in patients with cerebellar lesions. High-frequency repetitive transcranial magnetic stimulation (rTMS) induces cortical facilitation which can counteract the reduced cerebellar drive to the MC. Our study included 24 relapsing-remitting multiple sclerosis (RRMS) and secondary progressive multiple sclerosis (SPMS) patients with dysmetria. The patients were divided into two groups: Group A received two sessions of real MC rTMS and Group B received one session of real rTMS and one session of sham rTMS. Ten healthy volunteers formed group C. Evaluation was carried out using the nine-hole pegboard task and the cerebellar functional system score (FSS) of the expanded disability status scale (EDSS). Group A patients showed a significant improvement in the time required to finish the pegboard task (P = 0.002) and in their cerebellar FSS (P = 0.000) directly after the second session and 1 month later. The RRMS patients showed more improvement than the SPMS patients. Group B patients did not show any improvement in the pegboard task or the cerebellar FSS. These results indicate that MC rTMS can be a promising option in treating both RRMS or SPMS patients with cerebellar impairment and that its effect can be long-lasting.

  18. Neurochemical Analysis of Primary Motor Cortex in Chronic Low Back Pain

    Directory of Open Access Journals (Sweden)

    Anda E. Popescu

    2012-08-01

    Full Text Available The involvement of the primary motor cortex (M1 in chronic low back pain (LBP is a relatively new concept. Decreased M1 excitability and an analgesic effect after M1 stimulation have been recently reported. However, the neurochemical changes underlying these functional M1 changes are unknown. The current study investigated whether neurochemicals specific to neurons and glial cells in both right and left M1 are altered. N-Acetylaspartate (NAA and myo-inositol (mI were measured with proton magnetic resonance spectroscopy in 19 subjects with chronic LBP and 14 healthy controls. We also examined correlations among neurochemicals within and between M1 and relationships between neurochemical concentrations and clinical features of pain. Right M1 NAA was lower in subjects with LBP compared to controls (p = 0.008. Left M1 NAA and mI were not significantly different between LBP and control groups. Correlations between neurochemical concentrations across M1s were different between groups (p = 0.008. There were no significant correlations between M1 neurochemicals and pain characteristics. These findings provide preliminary evidence of neuronal depression and altered neuronal-glial interactions across M1 in chronic LBP.

  19. Measurement of voluntary activation based on transcranial magnetic stimulation over the motor cortex.

    Science.gov (United States)

    Todd, Gabrielle; Taylor, Janet L; Gandevia, Simon C

    2016-09-01

    This article reviews the use of transcranial magnetic stimulation (TMS) over the motor cortex to make estimates of the level of voluntary drive to muscles. The method, described in 2003 (Todd et al. J Physiol 551: 661-671, 2003), uses a TMS pulse to produce descending corticospinal volleys that synaptically activate motoneurons, resulting in a muscle twitch. Linear regression of the superimposed twitch amplitude and voluntary force (or torque) can generate an "estimated" resting twitch for muscles involved in a task. This procedure has most commonly been applied to elbow flexors but also to knee extensors and other muscle groups. Data from 44 papers using the method were tabulated. We identify and discuss five major technical challenges, and the frequency with which they are addressed. The technical challenges include inadvertent activation of the cortical representation of antagonist muscles, the role of antagonist torques at the studied joint, uncertainty about the effectiveness of the TMS pulse in activating the motoneuron pool, the linearity of the voluntary force (or torque) and superimposed twitch relationship, and variability in the TMS-evoked EMG and force/torque responses. The ideal situation in which the descending corticospinal volleys recruit all of the agonist motoneurons and none of the antagonist motoneurons is unlikely to ever occur, and hence results must be carefully examined to assess the authenticity of the voluntary activation estimates in the context of the experimental design. A partial compromise lies in the choice of stimulus intensity. We also identify aspects of the procedure that require further investigation.

  20. Different current intensities of anodal transcranial direct current stimulation do not differentially modulate motor cortex plasticity.

    Science.gov (United States)

    Kidgell, Dawson J; Daly, Robin M; Young, Kayleigh; Lum, Jarrod; Tooley, Gregory; Jaberzadeh, Shapour; Zoghi, Maryam; Pearce, Alan J

    2013-01-01

    Transcranial direct current stimulation (tDCS) is a noninvasive technique that modulates the excitability of neurons within the motor cortex (M1). Although the aftereffects of anodal tDCS on modulating cortical excitability have been described, there is limited data describing the outcomes of different tDCS intensities on intracortical circuits. To further elucidate the mechanisms underlying the aftereffects of M1 excitability following anodal tDCS, we used transcranial magnetic stimulation (TMS) to examine the effect of different intensities on cortical excitability and short-interval intracortical inhibition (SICI). Using a randomized, counterbalanced, crossover design, with a one-week wash-out period, 14 participants (6 females and 8 males, 22-45 years) were exposed to 10 minutes of anodal tDCS at 0.8, 1.0, and 1.2 mA. TMS was used to measure M1 excitability and SICI of the contralateral wrist extensor muscle at baseline, immediately after and 15 and 30 minutes following cessation of anodal tDCS. Cortical excitability increased, whilst SICI was reduced at all time points following anodal tDCS. Interestingly, there were no differences between the three intensities of anodal tDCS on modulating cortical excitability or SICI. These results suggest that the aftereffect of anodal tDCS on facilitating cortical excitability is due to the modulation of synaptic mechanisms associated with long-term potentiation and is not influenced by different tDCS intensities.

  1. Different Current Intensities of Anodal Transcranial Direct Current Stimulation Do Not Differentially Modulate Motor Cortex Plasticity

    Directory of Open Access Journals (Sweden)

    Dawson J. Kidgell

    2013-01-01

    Full Text Available Transcranial direct current stimulation (tDCS is a noninvasive technique that modulates the excitability of neurons within the motor cortex (M1. Although the aftereffects of anodal tDCS on modulating cortical excitability have been described, there is limited data describing the outcomes of different tDCS intensities on intracortical circuits. To further elucidate the mechanisms underlying the aftereffects of M1 excitability following anodal tDCS, we used transcranial magnetic stimulation (TMS to examine the effect of different intensities on cortical excitability and short-interval intracortical inhibition (SICI. Using a randomized, counterbalanced, crossover design, with a one-week wash-out period, 14 participants (6 females and 8 males, 22–45 years were exposed to 10 minutes of anodal tDCS at 0.8, 1.0, and 1.2 mA. TMS was used to measure M1 excitability and SICI of the contralateral wrist extensor muscle at baseline, immediately after and 15 and 30 minutes following cessation of anodal tDCS. Cortical excitability increased, whilst SICI was reduced at all time points following anodal tDCS. Interestingly, there were no differences between the three intensities of anodal tDCS on modulating cortical excitability or SICI. These results suggest that the aftereffect of anodal tDCS on facilitating cortical excitability is due to the modulation of synaptic mechanisms associated with long-term potentiation and is not influenced by different tDCS intensities.

  2. Long-term depression and associativity in rat primary motor cortex following thalamic stimulation.

    Science.gov (United States)

    Eckert, M J; Racine, R J

    2006-12-01

    Associativity is an attractive property of LTP in terms of its possible mechanism as a model for memory storage. In this study, we compare the effects of homosynaptic vs. associative stimulation on the induction of LTP and LTD in the neocortex of freely behaving rats. Using a callosal input to the motor cortex as a 'strong' input (one that potentiates reliably following homosynaptic stimulation), we paired activity of this pathway with a 'weak' thalamocortical pathway (one that does not potentiate when stimulated homosynaptically). Surprisingly, homosynaptic HFS caused a lasting depression of the field EPSP in the thalamocortical pathway. Analysis of this effect revealed that it was largely polysynaptic. Associative HFS (HFS applied to both pathways) not only failed to induce an LTP effect in the thalamocortical pathway, it increased the magnitude of the depression. Associative HFS did, however, facilitate LTP induction in the 'strong' callosal pathway. When comparing the effects of homosynaptic and associative LTD induction (HFS on one pathway anticorrelated with LFS on the other), we found that both protocols induced a similar magnitude of depression. These results show that HFS applied to the thalamocortical pathway causes a depression and this depression is enhanced, not reversed, by associative pairing with a strong input.

  3. Prediction of hand trajectory from electrocorticography signals in primary motor cortex.

    Directory of Open Access Journals (Sweden)

    Chao Chen

    Full Text Available Due to their potential as a control modality in brain-machine interfaces, electrocorticography (ECoG has received much focus in recent years. Studies using ECoG have come out with success in such endeavors as classification of arm movements and natural grasp types, regression of arm trajectories in two and three dimensions, estimation of muscle activity time series and so on. However, there still remains considerable work to be done before a high performance ECoG-based neural prosthetic can be realized. In this study, we proposed an algorithm to decode hand trajectory from 15 and 32 channel ECoG signals recorded from primary motor cortex (M1 in two primates. To determine the most effective areas for prediction, we applied two electrode selection methods, one based on position relative to the central sulcus (CS and another based on the electrodes' individual prediction performance. The best coefficients of determination for decoding hand trajectory in the two monkeys were 0.4815 ± 0.0167 and 0.7780 ± 0.0164. Performance results from individual ECoG electrodes showed that those with higher performance were concentrated at the lateral areas and areas close to the CS. The results of prediction according with different numbers of electrodes based on proposed methods were also shown and discussed. These results also suggest that superior decoding performance can be achieved from a group of effective ECoG signals rather than an entire ECoG array.

  4. Evidence for high-fidelity timing-dependent synaptic plasticity of human motor cortex.

    Science.gov (United States)

    Cash, R F H; Mastaglia, F L; Thickbroom, G W

    2013-01-01

    A single transcranial magnetic stimulation (TMS) pulse typically evokes a short series of spikes in corticospinal neurons [known as indirect (I)-waves] which are thought to arise from transynaptic input. Delivering a second pulse at inter-pulse intervals (IPIs) corresponding to the timing of these I-waves leads to a facilitation of the response, and if stimulus pairs are delivered repeatedly, a persistent LTP-like increase in excitability can occur. This has been demonstrated at an IPI of 1.5 ms, which corresponds to the first I-wave interval, in an intervention referred to as ITMS (I-wave TMS), and it has been argued that this may have similarities with timing-dependent plasticity models. Consequently, we hypothesized that if the second stimulus is delivered so as not to coincide with I-wave timing, it should lead to LTD. We performed a crossover study in 10 subjects in which TMS doublets were timed to coincide (1.5-ms IPI, ITMS(1.5)) or not coincide (2-ms IPI, ITMS(2)) with I-wave firing. Single pulse motor-evoked potential (MEP) amplitude, resting motor threshold (RMT), and short-interval cortical inhibition (SICI) were measured from the first dorsal interosseous (FDI) muscle. After ITMS(1.5) corticomotor excitability was increased by ~60% for 15 min (P < 0.05) and returned to baseline by 20 min. Increasing the IPI by just 500 μs to 2 ms reversed the aftereffect, and MEP amplitude was significantly reduced (~35%, P < 0.05) for 15 min before returning to baseline. This reduction was not associated with an increase in SICI, suggesting a reduction in excitatory transmission rather than an increase in inhibitory efficacy. RMT also remained unchanged, suggesting that these changes were not due to changes in membrane excitability. Amplitude-matching ITMS(2) did not modulate excitability. The results are consistent with timing-dependent synaptic LTP/D-like effects and suggest that there are plasticity mechanisms operating in the human motor cortex with a temporal

  5. Electrical stimulation of the motor cortex enhances treatment outcome in post-stroke aphasia.

    Science.gov (United States)

    Meinzer, Marcus; Darkow, Robert; Lindenberg, Robert; Flöel, Agnes

    2016-04-01

    Transcranial direct current stimulation has shown promise to improve recovery in patients with post-stroke aphasia, but previous studies have only assessed stimulation effects on impairment parameters, and evidence for long-term maintenance of transcranial direct current stimulation effects from randomized, controlled trials is lacking. Moreover, due to the variability of lesions and functional language network reorganization after stroke, recent studies have used advanced functional imaging or current modelling to determine optimal stimulation sites in individual patients. However, such approaches are expensive, time consuming and may not be feasible outside of specialized research centres, which complicates incorporation of transcranial direct current stimulation in day-to-day clinical practice. Stimulation of an ancillary system that is functionally connected to the residual language network, namely the primary motor system, would be more easily applicable, but effectiveness of such an approach has not been explored systematically. We conducted a randomized, parallel group, sham-controlled, double-blind clinical trial and 26 patients with chronic aphasia received a highly intensive naming therapy over 2 weeks (8 days, 2 × 1.5 h/day). Concurrently, anodal-transcranial direct current stimulation was administered to the left primary motor cortex twice daily at the beginning of each training session. Naming ability for trained items (n = 60 pictures that could not be named during repeated baseline assessments), transfer to untrained items (n = 284 pictures) and generalization to everyday communication were assessed immediately post-intervention and 6 months later. Naming ability for trained items was significantly improved immediately after the end of the intervention in both the anodal (Cohen's d = 3.67) and sham-transcranial direct current stimulation groups (d = 2.10), with a trend for larger gains in the anodal-transcranial direct current stimulation group (d

  6. Dissociation of supplementary motor area and primary motor cortex in human subjects when comparing index and little finger movements with functional magnetic resonance imaging.

    Science.gov (United States)

    Erdler, M; Windischberger, C; Lanzenberger, R; Edward, V; Gartus, A; Deecke, L; Beisteiner, R

    2001-11-02

    This study provides the first investigation of supplementary motor area (SMA) and primary motor cortex (MI) activation with similar movements differing only in subjective difficulty of motor control. Brain activation with simple tapping of the right index finger (well trained during daily life and easy to perform) was compared with tapping of the little finger (less trained and difficult to perform) using functional magnetic resonance imaging at 3 Tesla. Due to optimised movement standardisation, extrinsic influences on activation levels such as movement complexity, amplitude and frequency were minimised. Fifth finger tapping significantly increased the number of activated SMA voxels by 450% whereas MI activation showed no significant difference between fingers. We conclude that with similar movements the degree of subjective difficulty specifically modifies SMA but not MI activation.

  7. Supplementary motor area and primary auditory cortex activation in an expert break-dancer during the kinesthetic motor imagery of dance to music.

    Science.gov (United States)

    Olshansky, Michael P; Bar, Rachel J; Fogarty, Mary; DeSouza, Joseph F X

    2015-01-01

    The current study used functional magnetic resonance imaging to examine the neural activity of an expert dancer with 35 years of break-dancing experience during the kinesthetic motor imagery (KMI) of dance accompanied by highly familiar and unfamiliar music. The goal of this study was to examine the effect of musical familiarity on neural activity underlying KMI within a highly experienced dancer. In order to investigate this in both primary sensory and motor planning cortical areas, we examined the effects of music familiarity on the primary auditory cortex [Heschl's gyrus (HG)] and the supplementary motor area (SMA). Our findings reveal reduced HG activity and greater SMA activity during imagined dance to familiar music compared to unfamiliar music. We propose that one's internal representations of dance moves are influenced by auditory stimuli and may be specific to a dance style and the music accompanying it.

  8. Real time adenosine fluctuations detected with fast-scan cyclic voltammetry in the rat striatum and motor cortex.

    Science.gov (United States)

    Adamah-Biassi, Ekue B; Almonte, Antoine G; Blagovechtchenski, Evgeny; Grinevich, Valentina P; Weiner, Jeff L; Bonin, Keith D; Budygin, Evgeny A

    2015-12-30

    Adenosine serves many functions within the CNS, including inhibitory and excitatory control of neurotransmission. The understanding of adenosine dynamics in the brain is of fundamental importance. The goal of the present study was to explore subsecond adenosine fluctuations in the rat brain in vivo. Long Evans rats were anesthetized and a carbon fiber electrode was positioned in the motor cortex or dorsal striatum. Real time electrochemical recordings were made at the carbon fiber electrodes every 100ms by applying a triangular waveform (-0.4 to +1.5V, 400V/s). Adenosine spikes were identified by the background-subtracted cyclic voltammogram. The frequency of detected adenosine spikes was relatively stable in both tested regions, and the time intervals between spikes were regular and lasted from 1 to 5s within an animal. Spike frequency ranged from 0.5 to 1.5Hz in both the motor cortex and the dorsal striatum. Average spike amplitudes were 85±11 and 66±7nM for the motor cortex and the dorsal striatum, respectively. The current study established that adenosine signaling can operate on a fast time scale (within seconds) to modulate brain functions. This finding suggests that spontaneous adenosine release may play a fast, dynamic role in regulating an organism's response to external events. Therefore, adenosine transmission in the brain may have characteristics similar to those of classical neurotransmitters, such as dopamine and norepinephrine. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Cortico-cortical connectivity between right parietal and bilateral primary motor cortices during imagined and observed actions: A combined TMS/tDCS study.

    Directory of Open Access Journals (Sweden)

    Matteo eFeurra

    2011-08-01

    Full Text Available Previous TMS studies showed functional connections between the parietal cortex (PC and the primary motor cortex (M1 during tasks of different reaching-to-grasp movements. Here, we tested whether the same network is involved in cognitive processes such as imagined or observed actions. Single pulse TMS of the right and left M1 during rest and during a motor imagery and an action observation task (i.e. an index-thumb pinch grip in both cases was used to measure corticospinal excitability changes before and after conditioning of the right PC by 10 minutes of cathodal, anodal or sham transcranial direct current stimulation (tDCS. Corticospinal excitability was indexed by the size of motor evoked potentials (MEPs from the contralateral FDI (target and ADM (control muscles. Results showed selective ipsilateral effects on the M1 excitability, exclusively for motor imagery processes: anodal tDCS enhanced the MEPs’ size from the FDI muscle, whereas cathodal tDCS decreased it. Only cathodal tDCS impacted corticospinal facilitation induced by action observation. Sham stimulation was always uneffective. These results suggest that motor imagery, differently from action observation, is sustained by a strictly ipsilateral parieto-motor cortex circuits. Results might have implication for neuromodulatory rehabilitative purposes.

  10. Comparison of descending volleys evoked by transcranial and epidural motor cortex stimulation in a conscious patient with bulbar pain.

    Science.gov (United States)

    Di Lazzaro, V; Oliviero, A; Pilato, F; Saturno, E; Dileone, M; Meglio, M; Cioni, B; Papacci, F; Tonali, P A; Rothwell, J C

    2004-04-01

    To compare the pattern of activation of motor cortex produced by transcranial magnetic stimulation and epidural electrical stimulation. The spinal volleys evoked by transcranial magnetic stimulation and epidural electrical stimulation over the cerebral motor cortex were recorded from an electrode inserted into the cervical epidural space of one conscious subject who also had a cortical epidural electrode over the motor area. The volleys were termed D- and I-waves according to their latency. Magnetic stimulation was performed with a figure-of-eight coil and the induced current flowed either in a postero-anterior (PA) or in latero-medial (LM) direction. At active motor threshold intensity LM magnetic stimulation evoked a D wave whereas PA stimulation evoked an I(1) wave with later I waves being recruited at increasing stimulus intensities. Electrical epidural stimulation evoked both a D wave and I waves. However, the D wave evoked by electrical epidural stimulation had a longer latency than the LM D wave, suggesting either a more proximal site of activation of the pyramidal axon or activation of slightly faster conducting set of corticospinal fibres by LM stimulation. The I3 wave evoked by electrical epidural stimulation also had a longer latency than the PA I3-wave Epidural stimulation of the motor cortex can produce repetitive excitation of corticospinal neurones. The order of recruitment of the volleys, and the latency of the D and I3 waves may be slightly different to that seen after transcranial magnetic stimulation. Our findings suggest that there may be subtle differences in the populations of neurones activated by the two forms of stimulation.

  11. Recovery of post stroke proximal arm function, driven by complex neuroplastic bilateral brain activation patterns and predicted by baseline motor dysfunction severity

    Directory of Open Access Journals (Sweden)

    Svetlana ePundik

    2015-07-01

    Full Text Available Objectives: Neuroplastic changes that drive recovery of shoulder/elbow function after stoke have been poorly understood. The purpose of this study was to determine the relationship between neuroplastic brain changes related to shoulder/elbow movement control in response to treatment and recovery of arm motor function in chronic stroke survivors. Methods: Twenty-three chronic stroke survivors were treated with 12 weeks of arm rehabilitation. Outcome measures included functional Magnetic Resonance Imaging (fMRI for the shoulder/elbow components of reach and a skilled motor function test (Arm Motor Abilities Test (AMAT, collected before and after treatment.Results: We observed two patterns of neuroplastic changes that were associated with gains in motor function: decreased or increased task-related brain activation. Those with significantly better motor function at baseline exhibited a decrease in brain activation in response to treatment, evident in the ipsilesional primary motor and contralesional supplementary motor regions; in contrast, those with greater baseline motor impairment, exhibited increased brain activation in response to treatment. There was an linear relationship between greater functional gain (AMAT and increased activation in bilateral primary motor, contralesional primary and secondary sensory regions, and contralesional lateral premotor area, after adjusting for baseline AMAT, age, and time since stroke. Conclusions: Recovery of functional reach involves recruitment of several contralesional and bilateral primary motor regions. In response to intensive therapy, the direction of functional brain change (i.e. increase or decrease in task-related brain recruitment for shoulder/elbow reach components depends on baseline level of motor function and may represent either different phases or different strategies of neuroplasticity that drive functional recovery.

  12. Recovery of post stroke proximal arm function, driven by complex neuroplastic bilateral brain activation patterns and predicted by baseline motor dysfunction severity

    Science.gov (United States)

    Pundik, Svetlana; McCabe, Jessica P.; Hrovat, Ken; Fredrickson, Alice Erica; Tatsuoka, Curtis; Feng, I Jung; Daly, Janis J.

    2015-01-01

    Objectives: Neuroplastic changes that drive recovery of shoulder/elbow function after stroke have been poorly understood. The purpose of this study was to determine the relationship between neuroplastic brain changes related to shoulder/elbow movement control in response to treatment and recovery of arm motor function in chronic stroke survivors.Methods: Twenty-three chronic stroke survivors were treated with 12 weeks of arm rehabilitation. Outcome measures included functional Magnetic Resonance Imaging (fMRI) for the shoulder/elbow components of reach and a skilled motor function test (Arm Motor Abilities Test, AMAT), collected before and after treatment.Results: We observed two patterns of neuroplastic changes that were associated with gains in motor function: decreased or increased task-related brain activation. Those with significantly better motor function at baseline exhibited a decrease in brain activation in response to treatment, evident in the ipsilesional primary motor and contralesional supplementary motor regions; in contrast, those with greater baseline motor impairment, exhibited increased brain activation in response to treatment. There was a linear relationship between greater functional gain (AMAT) and increased activation in bilateral primary motor, contralesional primary and secondary sensory regions, and contralesional lateral premotor area, after adjusting for baseline AMAT, age, and time since stroke.Conclusions: Recovery of functional reach involves recruitment of several contralesional and bilateral primary motor regions. In response to intensive therapy, the direction of functional brain change (i.e., increase or decrease in task-related brain recruitment) for shoulder/elbow reach components depends on baseline level of motor function and may represent either different phases of recovery or different patterns of neuroplasticity that drive functional recovery. PMID:26257623

  13. Regional glucose hypometabolic spread within the primary motor cortex is associated with amyotrophic lateral sclerosis disease progression: A fluoro-deoxyglucose positron emission tomography study

    Directory of Open Access Journals (Sweden)

    Hironobu Endo

    2017-03-01

    Conclusions: In patients with ALS, glucose metabolism decreased in the impaired side of the primary motor cortex depending on the clinical symptom progression in the corresponding extremities, regardless of the presence of clinical UMN signs. A decrement in glucose metabolism on FDG-PET corresponding to symptoms in the primary motor cortex might be an indicator of the time-dependent course of ALS neurodegeneration.

  14. The laminar organization of the motor cortex in monodactylous mammals: a comparative assessment based on horse, chimpanzee, and macaque.

    Science.gov (United States)

    Cozzi, Bruno; De Giorgio, Alberto; Peruffo, A; Montelli, S; Panin, M; Bombardi, C; Grandis, A; Pirone, A; Zambenedetti, P; Corain, L; Granato, Alberto

    2017-08-01

    The architecture of the neocortex classically consists of six layers, based on cytological criteria and on the layout of intra/interlaminar connections. Yet, the comparison of cortical cytoarchitectonic features across different species proves overwhelmingly difficult, due to the lack of a reliable model to analyze the connection patterns of neuronal ensembles forming the different layers. We first defined a set of suitable morphometric cell features, obtained in digitized Nissl-stained sections of the motor cortex of the horse, chimpanzee, and crab-eating macaque. We then modeled them using a quite general non-parametric data representation model, showing that the assessment of neuronal cell complexity (i.e., how a given cell differs from its neighbors) can be performed using a suitable measure of statistical dispersion such as the mean absolute deviation-mean absolute deviation (MAD). Along with the non-parametric combination and permutation methodology, application of MAD allowed not only to estimate, but also to compare and rank the motor cortical complexity across different species. As to the instances presented in this paper, we show that the pyramidal layers of the motor cortex of the horse are far more irregular than those of primates. This feature could be related to the different organizations of the motor system in monodactylous mammals.

  15. Neurological Change after Gamma Knife Radiosurgery for Brain Metastases Involving the Motor Cortex

    Science.gov (United States)

    Park, Chang-Yong; Choi, Hyun-Yong; Lee, Sang-Ryul; Roh, Tae Hoon; Seo, Mi-Ra

    2016-01-01

    Background Although Gamma Knife radiosurgery (GKRS) can provide beneficial therapeutic effects for patients with brain metastases, lesions involving the eloquent areas carry a higher risk of neurologic deterioration after treatment, compared to those located in the non-eloquent areas. We aimed to investigate neurological change of the patients with brain metastases involving the motor cortex (MC) and the relevant factors related to neurological deterioration after GKRS. Methods We retrospectively reviewed clinical, radiological and dosimetry data of 51 patients who underwent GKRS for 60 brain metastases involving the MC. Prior to GKRS, motor deficits existed in 26 patients (50.9%). The mean target volume was 3.2 cc (range 0.001–14.1) at the time of GKRS, and the mean prescription dose was 18.6 Gy (range 12–24 Gy). Results The actuarial median survival time from GKRS was 19.2±5.0 months. The calculated local tumor control rates at 6 and 12 months after GKRS were 89.7% and 77.4%, respectively. During the median clinical follow-up duration of 12.3±2.6 months (range 1–54 months), 18 patients (35.3%) experienced new or worsened neurologic deficits with a median onset time of 2.5±0.5 months (range 0.3–9.7 months) after GKRS. Among various factors, prescription dose (>20 Gy) was a significant factor for the new or worsened neurologic deficits in univariate (p=0.027) and multivariate (p=0.034) analysis. The managements of 18 patients were steroid medication (n=10), boost radiation therapy (n=5), and surgery (n=3), and neurological improvement was achieved in 9 (50.0%). Conclusion In our series, prescription dose (>20 Gy) was significantly related to neurological deterioration after GKRS for brain metastases involving the MC. Therefore, we suggest that careful dose adjustment would be required for lesions involving the MC to avoid neurological deterioration requiring additional treatment in the patients with limited life expectancy. PMID:27867921

  16. Motor cortex stimulation for the treatment of refractory peripheral neuropathic pain.

    Science.gov (United States)

    Lefaucheur, Jean-Pascal; Drouot, Xavier; Cunin, Patrick; Bruckert, Rémy; Lepetit, Hélène; Créange, Alain; Wolkenstein, Pierre; Maison, Patrick; Keravel, Yves; Nguyen, Jean-Paul

    2009-06-01

    Epidural motor cortex stimulation (MCS) has been proposed as a treatment for chronic, drug-resistant neuropathic pain of various origins. Regarding pain syndromes due to peripheral nerve lesion, only case series have previously been reported. We present the results of the first randomized controlled trial using chronic MCS in this indication. Sixteen patients were included with pain origin as follows: trigeminal neuralgia (n = 4), brachial plexus lesion (n = 4), neurofibromatosis type-1 (n = 3), upper limb amputation (n = 2), herpes zoster ophthalmicus (n = 1), atypical orofacial pain secondary to dental extraction (n = 1) and traumatic nerve trunk transection in a lower limb (n = 1). A quadripolar lead was implanted, under radiological and electrophysiological guidance, for epidural cortical stimulation. A randomized crossover trial was performed between 1 and 3 months postoperative, during which the stimulator was alternatively switched 'on' and 'off' for 1 month, followed by an open phase during which the stimulator was switched 'on' in all patients. Clinical assessment was performed up to 1 year after implantation and was based on the following evaluations: visual analogue scale (VAS), brief pain inventory, McGill Pain questionnaire, sickness impact profile and medication quantification scale. The crossover trial included 13 patients and showed a reduction of the McGill Pain questionnaire-pain rating index (P = 0.0166, Wilcoxon test) and McGill Pain questionnaire sensory subscore (P = 0.01) when the stimulator was switched 'on' compared to the 'off-stimulation' condition. However, these differences did not persist after adjustment for multiple comparisons. In the 12 patients who completed the open study, the VAS and sickness impact profile scores varied significantly in the follow-up and were reduced at 9-12 months postoperative, compared to the preoperative baseline. At final examination, the mean rate of pain relief on VAS scores was 48% (individual results

  17. Whisker motor cortex reorganization after superior colliculus output suppression in adult rats.

    Science.gov (United States)

    Veronesi, Carlo; Maggiolini, Emma; Franchi, Gianfranco

    2013-10-01

    The effect of unilateral superior colliculus (SC) output suppression on the ipsilateral whisker motor cortex (WMC) was studied at different time points after tetrodotoxin and quinolinic acid injections, in adult rats. The WMC output was assessed by mapping the movement evoked by intracortical microstimulation (ICMS) and by recording the ICMS-evoked electromyographic (EMG) responses from contralateral whisker muscles. At 1 h after SC injections, the WMC showed: (i) a strong decrease in contralateral whisker sites, (ii) a strong increase in ipsilateral whisker sites and in ineffective sites, and (iii) a strong increase in threshold current values. At 6 h after injections, the WMC size had shrunk to 60% of the control value and forelimb representation had expanded into the lateral part of the normal WMC. Thereafter, the size of the WMC recovered, returning to nearly normal 12 h later (94% of control) and persisted unchanged over time (1-3 weeks). The ICMS-evoked EMG response area decreased at 1 h after SC lesion and had recovered its baseline value 12 h later. Conversely, the latency of ICMS-evoked EMG responses had increased by 1 h and continued to increase for as long as 3 weeks following the lesion. These findings provide physiological evidence that SC output suppression persistently withdrew the direct excitatory drive from whisker motoneurons and induced changes in the WMC. We suggest that the changes in the WMC are a form of reversible short-term reorganization that is induced by SC lesion. The persistent latency increase in the ICMS-evoked EMG response suggested that the recovery of basic WMC excitability did not take place with the recovery of normal explorative behaviour. © 2013 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  18. Comparison of neural responses in primary motor cortex to transient and continuous loads during posture.

    Science.gov (United States)

    Herter, Troy M; Korbel, Tereza; Scott, Stephen H

    2009-01-01

    The present study examined whether neurons in primary motor cortex (M1) exhibit similar responses to transient and continuous loads applied during posture. Rapid responses to whole-limb perturbations were examined by transiently applying (300 ms) flexor and extensor torques to the shoulder and/or elbow during postural maintenance. Over half of M1 neurons responded to these transient loads within 80 ms and many responded within 20-40 ms. These rapid responses exhibited a broad continuum of modulation patterns across load directions. At one extreme, neurons exhibited reciprocal increases and decreases in activity for opposing loads. At the other extreme, neurons (particularly those with onset times of 20-40 ms) displayed relatively uniform increases in activity for all loads. Activity of proximal arm muscles displayed a narrower distribution of modulation patterns characterized by broadly tuned excitation combined with little or no reciprocal inhibition. Both neurons and muscles showed a directional preference for whole-limb flexor and whole-limb extensor torques (flexor at one joint and extensor at the other). Most neurons with rapid responses also showed steady-state responses to continuous loads, although these responses generally displayed reciprocal increases and decreases in activity for opposing loads. Importantly, the preferred-torque directions were quantitatively similar across tasks. For example, a neuron with a maximal rapid response to a transient elbow flexor torque tended to exhibit a maximal steady-state response to a continuous elbow flexor torque. Activity of proximal arm muscles also showed this preservation of directional tuning. These results illustrate that M1 neurons respond rapidly to transient multijoint loads and their patterns of activity share some, but not all, features related to continuous multijoint loads applied during posture.

  19. Augmenting LTP-Like Plasticity in Human Motor Cortex by Spaced Paired Associative Stimulation.

    Directory of Open Access Journals (Sweden)

    Florian Müller-Dahlhaus

    Full Text Available Paired associative stimulation (PASLTP of the human primary motor cortex (M1 can induce LTP-like plasticity by increasing corticospinal excitability beyond the stimulation period. Previous studies showed that two consecutive PASLTP protocols interact by homeostatic metaplasticity, but animal experiments provided evidence that LTP can be augmented by repeated stimulation protocols spaced by ~30 min. Here we tested in twelve healthy selected PASLTP responders the possibility that LTP-like plasticity can be augmented in the human M1 by systematically varying the interval between two consecutive PASLTP protocols. The first PASLTP protocol (PAS1 induced strong LTP-like plasticity lasting for 30-60 min. The effect of a second identical PASLTP protocol (PAS2 critically depended on the time between PAS1 and PAS2. At 10 min, PAS2 prolonged the PAS1-induced LTP-like plasticity. At 30 min, PAS2 augmented the LTP-like plasticity induced by PAS1, by increasing both magnitude and duration. At 60 min and 180 min, PAS2 had no effect on corticospinal excitability. The cumulative LTP-like plasticity after PAS1 and PAS2 at 30 min exceeded significantly the effect of PAS1 alone, and the cumulative PAS1 and PAS2 effects at 60 min and 180 min. In summary, consecutive PASLTP protocols interact in human M1 in a time-dependent manner. If spaced by 30 min, two consecutive PASLTP sessions can augment LTP-like plasticity in human M1. Findings may inspire further research on optimized therapeutic applications of non-invasive brain stimulation in neurological and psychiatric diseases.

  20. Oxidative stress induced by cumene hydroperoxide evokes changes in neuronal excitability of rat motor cortex neurons.

    Science.gov (United States)

    Pardillo-Díaz, R; Carrascal, L; Ayala, A; Nunez-Abades, P

    2015-03-19

    Oxidative stress and the production of reactive oxygen radicals play a key role in neuronal cell damage. This paper describes an in vitro study that explores the neuronal responses to oxidative stress focusing on changes in neuronal excitability and functional membrane properties. This study was carried out in pyramidal cells of the motor cortex by applying whole-cell patch-clamp techniques on brain slices from young adult rats. Oxygen-derived free radical formation was induced by bath application of 10μM cumene hydroperoxide (CH) for 30min. CH produced marked changes in the electrophysiological properties of neurons (n=30). Resting membrane potential became progressively depolarized, as well as depolarization voltage, with no variations in voltage threshold. Membrane resistance showed a biphasic behavior, increasing after 5min of drug exposure and then it started to decrease, even under control values, after 15 and 30min. At the same time, changes in membrane resistance produced compensatory variations in the rheobase. The amplitude of the action potentials diminished and the duration increased progressively over time. Some of the neurons under study also lost their ability to discharge action potentials in a repetitive way. Most of the neurons, however, kept their repetitive discharge even though their maximum frequency and gain decreased. Furthermore, cancelation of the repetitive firing discharge took place at intensities that decreased with time of exposure to CH, which resulted in a narrower working range. We can conclude that oxidative stress compromises both neuronal excitability and the capability of generating action potentials, and so this type of neuronal functional failure could precede the neuronal death characteristics of many neurodegenerative diseases.

  1. Expressions of multiple neuronal dynamics during sensorimotor learning in the motor cortex of behaving monkeys.

    Directory of Open Access Journals (Sweden)

    Yael Mandelblat-Cerf

    Full Text Available Previous studies support the notion that sensorimotor learning involves multiple processes. We investigated the neuronal basis of these processes by recording single-unit activity in motor cortex of non-human primates (Macaca fascicularis, during adaptation to force-field perturbations. Perturbed trials (reaching to one direction were practiced along with unperturbed trials (to other directions. The number of perturbed trials relative to the unperturbed ones was either low or high, in two separate practice schedules. Unsurprisingly, practice under high-rate resulted in faster learning with more pronounced generalization, as compared to the low-rate practice. However, generalization and retention of behavioral and neuronal effects following practice in high-rate were less stable; namely, the faster learning was forgotten faster. We examined two subgroups of cells and showed that, during learning, the changes in firing-rate in one subgroup depended on the number of practiced trials, but not on time. In contrast, changes in the second subgroup depended on time and practice; the changes in firing-rate, following the same number of perturbed trials, were larger under high-rate than low-rate learning. After learning, the neuronal changes gradually decayed. In the first subgroup, the decay pace did not depend on the practice rate, whereas in the second subgroup, the decay pace was greater following high-rate practice. This group shows neuronal representation that mirrors the behavioral performance, evolving faster but also decaying faster at learning under high-rate, as compared to low-rate. The results suggest that the stability of a new learned skill and its neuronal representation are affected by the acquisition schedule.

  2. Augmenting LTP-Like Plasticity in Human Motor Cortex by Spaced Paired Associative Stimulation.

    Science.gov (United States)

    Müller-Dahlhaus, Florian; Lücke, Caroline; Lu, Ming-Kuei; Arai, Noritoshi; Fuhl, Anna; Herrmann, Eva; Ziemann, Ulf

    2015-01-01

    Paired associative stimulation (PASLTP) of the human primary motor cortex (M1) can induce LTP-like plasticity by increasing corticospinal excitability beyond the stimulation period. Previous studies showed that two consecutive PASLTP protocols interact by homeostatic metaplasticity, but animal experiments provided evidence that LTP can be augmented by repeated stimulation protocols spaced by ~30 min. Here we tested in twelve healthy selected PASLTP responders the possibility that LTP-like plasticity can be augmented in the human M1 by systematically varying the interval between two consecutive PASLTP protocols. The first PASLTP protocol (PAS1) induced strong LTP-like plasticity lasting for 30-60 min. The effect of a second identical PASLTP protocol (PAS2) critically depended on the time between PAS1 and PAS2. At 10 min, PAS2 prolonged the PAS1-induced LTP-like plasticity. At 30 min, PAS2 augmented the LTP-like plasticity induced by PAS1, by increasing both magnitude and duration. At 60 min and 180 min, PAS2 had no effect on corticospinal excitability. The cumulative LTP-like plasticity after PAS1 and PAS2 at 30 min exceeded significantly the effect of PAS1 alone, and the cumulative PAS1 and PAS2 effects at 60 min and 180 min. In summary, consecutive PASLTP protocols interact in human M1 in a time-dependent manner. If spaced by 30 min, two consecutive PASLTP sessions can augment LTP-like plasticity in human M1. Findings may inspire further research on optimized therapeutic applications of non-invasive brain stimulation in neurological and psychiatric diseases.

  3. Dysphagia and neuropathic facial pain treated with motor cortex stimulation: case report.

    Science.gov (United States)

    Anderson, William S; Kiyofuji, Satoshi; Conway, James E; Busch, Chris; North, Richard B; Garonzik, Ira M

    2009-09-01

    We report on a patient with a neuropathic facial pain syndrome, including elements of trigeminal neuralgia, glossopharyngeal neuralgia, and dysphagia. After failing medical and surgical decompressive treatments, the patient underwent implantation of a motor cortex stimulation (MCS) system. A 54-year-old woman presented with a 14-year history of left-sided facial pain, throat pain, and associated nausea and vomiting. The patient failed several open surgical and percutaneous procedures for her facial pain syndrome. Additionally, several medication trial attempts were unsuccessful. Imaging studies were normal. The patient underwent placement of a right-sided MCS system for treatment of her neuropathic facial pain syndrome. The procedure was tolerated well, and the trial stimulator provided promising results. The permanent MCS generator needed to be reprogrammed at the time of the 5-week follow-up visit to optimize symptom relief. The patient demonstrated dramatic improvements in her neuropathic facial and oral pain, including improvements in swallowing toleration, after the 5-week follow-up examination with subthreshold MCS. A decline in treatment efficacy also occurred 2 years after implantation due to generator depletion. Symptom improvement returned with stimulation after the generator was replaced. A novel implantable MCS system was used to treat this patient's neuropathic facial pain. Durable improvements were noted not only in her facial pain, but also in swallowing toleration. The ultimate role of MCS in the treatment of pain conditions is still not well-defined but might play a part in refractory cases and, as in this case, might improve other functional issues, including dysphagia.

  4. The Effect of Visual and Auditory Enhancements on Excitability of the Primary Motor Cortex during Motor Imagery: A Pilot Study

    Science.gov (United States)

    Ikeda, Kohei; Higashi, Toshio; Sugawara, Kenichi; Tomori, Kounosuke; Kinoshita, Hiroshi; Kasai, Tatsuya

    2012-01-01

    The effect of visual and auditory enhancements of finger movement on corticospinal excitability during motor imagery (MI) was investigated using the transcranial magnetic stimulation technique. Motor-evoked potentials were elicited from the abductor digit minimi muscle during MI with auditory, visual and, auditory and visual information, and no…

  5. Effective Connectivity Hierarchically Links Temporoparietal and Frontal Areas of the Auditory Dorsal Stream with the Motor Cortex Lip Area during Speech Perception

    Science.gov (United States)

    Murakami, Takenobu; Restle, Julia; Ziemann, Ulf

    2012-01-01

    A left-hemispheric cortico-cortical network involving areas of the temporoparietal junction (Tpj) and the posterior inferior frontal gyrus (pIFG) is thought to support sensorimotor integration of speech perception into articulatory motor activation, but how this network links with the lip area of the primary motor cortex (M1) during speech…

  6. Effect of acute administration of Pistacia lentiscus L. essential oil on rat cerebral cortex following transient bilateral common carotid artery occlusion

    Directory of Open Access Journals (Sweden)

    Quartu Marina

    2012-01-01

    Full Text Available Abstract Background Ischemia/reperfusion leads to inflammation and oxidative stress which damages membrane highly polyunsaturated fatty acids (HPUFAs and eventually induces neuronal death. This study evaluates the effect of the administration of Pistacia lentiscus L. essential oil (E.O., a mixture of terpenes and sesquiterpenes, on modifications of fatty acid profile and endocannabinoid (eCB congener concentrations induced by transient bilateral common carotid artery occlusion (BCCAO in the rat frontal cortex and plasma. Methods Adult Wistar rats underwent BCCAO for 20 min followed by 30 min reperfusion (BCCAO/R. 6 hours before surgery, rats, randomly assigned to four groups, were gavaged either with E.O. (200 mg/0.45 ml of sunflower oil as vehicle or with the vehicle alone. Results BCCAO/R triggered in frontal cortex a decrease of docosahexaenoic acid (DHA, the membrane highly polyunsaturated fatty acid most susceptible to oxidation. Pre-treatment with E.O. prevented this change and led further to decreased levels of the enzyme cyclooxygenase-2 (COX-2, as assessed by Western Blot. In plasma, only after BCCAO/R, E.O. administration increased both the ratio of DHA-to-its precursor, eicosapentaenoic acid (EPA, and levels of palmytoylethanolamide (PEA and oleoylethanolamide (OEA. Conclusions Acute treatment with E.O. before BCCAO/R elicits changes both in the frontal cortex, where the BCCAO/R-induced decrease of DHA is apparently prevented and COX-2 expression decreases, and in plasma, where PEA and OEA levels and DHA biosynthesis increase. It is suggested that the increase of PEA and OEA plasma levels may induce DHA biosynthesis via peroxisome proliferator-activated receptor (PPAR alpha activation, protecting brain tissue from ischemia/reperfusion injury.

  7. Effects of Swimming Exercise on Limbic and Motor Cortex Neurogenesis in the Kainate-Lesion Model of Temporal Lobe Epilepsy

    Directory of Open Access Journals (Sweden)

    Vasavi R. Gorantla

    2016-01-01

    Full Text Available Temporal lobe epilepsy (TLE is a common neurological disease and antiseizure medication is often inadequate for preventing apoptotic cell death. Aerobic swimming exercise (EX augments neurogenesis in rats when initiated immediately in the postictal period. This study tests the hypothesis that aerobic exercise also augments neurogenesis over the long term. Male Wistar rats (age of 4 months were subjected to chemical lesioning using KA and to an EX intervention consisting of a 30 d period of daily swimming for 15 min, in one experiment immediately after KA lesioning (immediate exposure and in a second experiment after a 60 d period of normal activity (delayed exposure. Morphometric counting of neuron numbers (NN and dendritic branch points and intersections (DDBPI was performed in the CA1, CA3, and dentate regions of hippocampus, in basolateral nucleus of amygdala, and in several areas of motor cortex. EX increased NN and DDBPI in the normal control and the KA-lesioned rats in all four limbic and motor cortex areas studied, after both immediate and 60 d delayed exposures to exercise. These findings suggest that, after temporal lobe epileptic seizures in rats, swimming exercise may improve neural plasticity in areas of the brain involved with emotional regulation and motor coordination, even if the exercise treatment is delayed.

  8. Mice lacking the transcriptional coactivator PGC-1α exhibit alterations in inhibitory synaptic transmission in the motor cortex.

    Science.gov (United States)

    Dougherty, S E; Bartley, A F; Lucas, E K; Hablitz, J J; Dobrunz, L E; Cowell, R M

    2014-06-20

    Peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) is a transcriptional coactivator known to regulate gene programs in a cell-specific manner in energy-demanding tissues, and its dysfunction has been implicated in numerous neurological and psychiatric disorders. Previous work from the Cowell laboratory indicates that PGC-1α is concentrated in inhibitory interneurons and is required for the expression of the calcium buffer parvalbumin (PV) in the cortex; however, the impact of PGC-1α deficiency on inhibitory neurotransmission in the motor cortex is not known. Here, we show that mice lacking PGC-1α exhibit increased amplitudes and decreased frequency of spontaneous inhibitory postsynaptic currents in layer V pyramidal neurons. Upon repetitive train stimulation at the gamma frequency, decreased GABA release is observed. Furthermore, PV-positive interneurons in PGC-1α -/- mice display reductions in intrinsic excitability and excitatory input without changes in gross interneuron morphology. Taken together, these data show that PGC-1α is required for normal inhibitory neurotransmission and cortical PV-positive interneuron function. Given the pronounced motor dysfunction in PGC-1α -/- mice and the essential role of PV-positive interneurons in maintenance of cortical excitatory:inhibitory balance, it is possible that deficiencies in PGC-1α expression could contribute to cortical hyperexcitability and motor abnormalities in multiple neurological disorders.

  9. Involvement of the human dorsal premotor cortex in unimanual motor control: an interference approach using transcranial magnetic stimulation.

    Science.gov (United States)

    Cincotta, Massimo; Borgheresi, Alessandra; Balestrieri, Fabrizio; Giovannelli, Fabio; Rossi, Simone; Ragazzoni, Aldo; Zaccara, Gaetano; Ziemann, Ulf

    2004-09-02

    Unilateral movements are enabled through a distributed network of motor cortical areas but the relative contribution from the parts of this network is largely unknown. Failure of this network potentially results in mirror activation of the primary motor cortex (M1) ipsilateral to the intended movement. Here we tested the role of the right dorsal premotor cortex (dPMC) in 11 healthy subjects by disrupting its activity with 20 Hz repetitive transcranial magnetic stimulation (rTMS) whilst the subjects exerted a unilateral contraction of the left first dorsal interosseous (FDI). We found that disruption of right dPMC enhanced mirror activation of the ipsilateral left M1, as probed by motor evoked potential (MEP) amplitude to the right FDI. This was not the case with sham rTMS, when rTMS was directed to the right M1, or with rTMS of the right dPMC but without contraction of the left FDI. Findings suggest that activity in the dPMC contributes to the suppression of mirror movements during intended unilateral movements.

  10. Probing the corticospinal link between the motor cortex and motoneurones: some neglected aspects of human motor cortical function

    DEFF Research Database (Denmark)

    Petersen, Nicolas Caesar; Butler, Jane E.; Taylor, Janet L.

    2010-01-01

    ABSTRACT This review considers the operation of the corticospinal system in primates. There is a relatively widespread cortical area containing corticospinal outputs to a single muscle and thus a motoneurone pool receives corticospinal input from a wide region of cortex. In addition, corticospina...

  11. Neuromagnetic fields accompanying unilateral and bilateral voluntary movements: topography and analysis of cortical sources.

    Science.gov (United States)

    Kristeva, R; Cheyne, D; Deecke, L

    1991-08-01

    Movement-related magnetic fields (MRMFs) accompanying left and right unilateral and bilateral finger flexions were studied in 6 right-handed subjects. Six different MRMF components occurring prior to, and during both unilateral and bilateral movements are described: a slow pre-movement readiness field (RF, 1-0.5 sec prior to movement onset); a motor field (MF) starting shortly before EMG onset; 3 separate "movement-evoked" fields following EMG onset (MEFI at 100 msec; MEFII at 225 msec; and MEFIII at 320 msec); and a "post-movement" field (PMF) following the movement itself. The bilateral topography of the RF and MF for both unilateral and bilateral movements suggested bilateral generators for both conditions. Least-squares fitting of equivalent current dipole sources also indicated bilateral sources for MF prior to both unilateral and bilateral movements with significantly greater strength of contralateral sources in the case of unilateral movements. Differences in pre-movement field patterns for left versus right unilateral movements indicated possible cerebral dominance effects as well. A single current dipole in the contralateral sensorimotor cortex could account for the MEFI for unilateral movements and bilateral sensorimotor sources for bilateral movements. Other MRMF components following EMG onset indicated similar sources in sensorimotor cortex related to sensory feedback or internal monitoring of the movement. The results are discussed with respect to the possible generators active in sensorimotor cortex during unilateral and bilateral movement preparation and execution and their significance for the study of cortical organization of voluntary movement.

  12. Neuroticism relates to daytime wakefulness and sleep devaluation via high neurophysiological efficiency in the bilateral prefrontal cortex: a preliminary study.

    Science.gov (United States)

    Yoshiike, Takuya; Kuriyama, Kenichi; Honma, Motoyasu; Ikeda, Hiroki; Kim, Yoshiharu

    2014-04-01

    Higher wake promotion against sleep drive boosts cognitive processing, but it also seems to increase the risk of insomnia by reinforcing an obsession with sleep in neurotic patients. To explore whether a personality trait of neuroticism simultaneously facilitates wake-promoting ability and sleep devaluation via a common regional prefrontal function under a sleep-restricted condition, working memory tasks were administered to 49 healthy humans after a 2-h sleep restriction. Higher wake-promoting ability demonstrated in a high-load task was correlated with lower bilateral prefrontal activation, as measured by near-infrared spectroscopy. Structural equation modeling revealed that neuroticism predicts sleep devaluation and wake-promoting ability via left and right regional prefrontal efficiency, respectively. Our results indicate that neuroticism-related neural efficiency increases resilience to sleepiness, but decreases sleep satisfaction.

  13. Modulatory Effects of the Ipsi and Contralateral Ventral Premotor Cortex (PMv) on the Primary Motor Cortex (M1) Outputs to Intrinsic Hand and Forearm Muscles in Cebus apella.

    Science.gov (United States)

    Quessy, Stephan; Côté, Sandrine L; Hamadjida, Adjia; Deffeyes, Joan; Dancause, Numa

    2016-10-01

    The ventral premotor cortex (PMv) is a key node in the neural network involved in grasping. One way PMv can carry out this function is by modulating the outputs of the primary motor cortex (M1) to intrinsic hand and forearm muscles. As many PMv neurons discharge when grasping with either arm, both PMv within the same hemisphere (ipsilateral; iPMv) and in the opposite hemisphere (contralateral; cPMv) could modulate M1 outputs. Our objective was to compare modulatory effects of iPMv and cPMv on M1 outputs to intrinsic hand and forearm muscles. We used paired-pulse protocols with intracortical microstimulations in capuchin monkeys. A conditioning stimulus was applied in either iPMv or cPMv simultaneously or prior to a test stimulus in M1 and the effects quantified in electromyographic signals. Modulatory effects from iPMv were predominantly facilitatory, and facilitation was much more common and powerful on intrinsic hand than forearm muscles. In contrast, while the conditioning of cPMv could elicit facilitatory effects, in particular to intrinsic hand muscles, it was much more likely to inhibit M1 outputs. These data show that iPMv and cPMv have very different modulatory effects on the outputs of M1 to intrinsic hand and forearm muscles. © The Author 2016. Published by Oxford University Press.

  14. Transcranial Direct Current Stimulation over the Medial Prefrontal Cortex and Left Primary Motor Cortex (mPFC-lPMC) Affects Subjective Beauty but Not Ugliness.

    Science.gov (United States)

    Nakamura, Koyo; Kawabata, Hideaki

    2015-01-01

    Neuroaesthetics has been searching for the neural bases of the subjective experience of beauty. It has been demonstrated that neural activities in the medial prefrontal cortex (mPFC) and the left primary motor cortex (lPMC) correlate with the subjective experience of beauty. Although beauty and ugliness seem to be semantically and conceptually opposite, it is still unknown whether these two evaluations represent extreme opposites in unitary or bivariate dimensions. In this study, we applied transcranial direct current stimulation (tDCS) to examine whether non-invasive brain stimulation modulates two types of esthetic evaluation; evaluating beauty and ugliness. Participants rated the subjective beauty and ugliness of abstract paintings before and after the application of tDCS. Application of cathodal tDCS over the mPFC with anode electrode over the lPMC, which induced temporal inhibition of neural excitability of the mPFC, led to a decrease in beauty ratings but not ugliness ratings. There were no changes in ratings of both beauty and ugliness when applying anodal tDCS or sham stimulation over the mPFC. Results from our experiment indicate that the mPFC and the lPMC have a causal role in generating the subjective experience of beauty, with beauty and ugliness evaluations constituting two distinct dimensions.

  15. Effects of diazepam and levodopa single doses on motor cortex plasticity modulation in healthy human subjects: A TMS study

    Directory of Open Access Journals (Sweden)

    Ilić Nela V.

    2012-01-01

    Full Text Available Introduction. Administration of pharmacological agents with specific actions on neurotransmitter systems is a powerful driver of functional cortical reorganization. Plastic reorganization of the motor cortex in humans studies by the use of non-invasive stimulation protocols, which mimic the Hebbian model of associative plasticity. Objective. Aiming to explore pharmacological modulation on human motor cortex plasticity, we tested healthy subjects after each dosage of diazepam, levodopa i placebo administration, using paired associative stimulation protocol (PAS that induce fenomena similar to a long-term potentiation and depression, as defined on the synaptic level. Methods. We analyzed effects of benzodiazepines (10 mg, levodopa (200 mg and placebo on PAS protocol in 14 healthy volunteers, using a double-blind placebo-controlled study design. PAS consisted of electrical stimuli pairs at n.medianus and magnetic pulses over the scalp (transcranial magnetic stimulation in precisely defined intervals (ISI was 10 and 25 ms for a total of about 15 minutes (200 pairs. MEP amplitudes before and after (0, 10, 20 and 30 minutes later interventional protocols were compared. Results. When protocols were applied with placebo depending on ISI (10 ms - inhibitory, 25 ms - facilitatory effects, MEP amplitudes decreased or increased, while values in the postinterventional period (0, 10, 20 and 30 min were compared with initial values before the use of SAS. The use of benzodiazepines caused the occlusion of LTP-like effect, in contrast to amplification effects recorded after the administration of levodopa. With respect to the LTD-like protocol, the reverse was true (ANOVA for repeat measurements p<0.001. Conclusion. Administration of GABA-ergic agonist diazepam interferes with the induction of associative plasticity in the motor cortex of healthy individuals, as opposed to the use of levodopa, which stimulates these processes. The observed effects point at a

  16. Constraint-Induced Movement Therapy Combined with Transcranial Direct Current Stimulation over Premotor Cortex Improves Motor Function in Severe Stroke: A Pilot Randomized Controlled Trial

    Science.gov (United States)

    Batista, Larissa M.; Nogueira, Lídia L. R. F.; de Oliveira, Eliane A.; de Carvalho, Antonio G. C.; Lima, Soriano S.; Santana, Jordânia R. M.; de Lima, Emerson C. C.; Fernández-Calvo, Bernardino

    2017-01-01

    Objective. We compared the effects of transcranial direct current stimulation at different cortical sites (premotor and motor primary cortex) combined with constraint-induced movement therapy for treatment of stroke patients. Design. Sixty patients were randomly distributed into 3 groups: Group A, anodal stimulation on premotor cortex and constraint-induced movement therapy; Group B, anodal stimulation on primary motor cortex and constraint-induced movement therapy; Group C, sham stimulation and constraint-induced movement therapy. Evaluations involved analysis of functional independence, motor recovery, spasticity, gross motor function, and muscle strength. Results. A significant improvement in primary outcome (functional independence) after treatment in the premotor group followed by primary motor group and sham group was observed. The same pattern of improvement was highlighted among all secondary outcome measures regarding the superior performance of the premotor group over primary motor and sham groups. Conclusions. Premotor cortex can contribute to motor function in patients with severe functional disabilities in early stages of stroke. This study was registered in ClinicalTrials.gov database (NCT 02628561). PMID:28250992

  17. Constraint-Induced Movement Therapy Combined with Transcranial Direct Current Stimulation over Premotor Cortex Improves Motor Function in Severe Stroke: A Pilot Randomized Controlled Trial.

    Science.gov (United States)

    Andrade, Suellen M; Batista, Larissa M; Nogueira, Lídia L R F; de Oliveira, Eliane A; de Carvalho, Antonio G C; Lima, Soriano S; Santana, Jordânia R M; de Lima, Emerson C C; Fernández-Calvo, Bernardino

    2017-01-01

    Objective. We compared the effects of transcranial direct current stimulation at different cortical sites (premotor and motor primary cortex) combined with constraint-induced movement therapy for treatment of stroke patients. Design. Sixty patients were randomly distributed into 3 groups: Group A, anodal stimulation on premotor cortex and constraint-induced movement therapy; Group B, anodal stimulation on primary motor cortex and constraint-induced movement therapy; Group C, sham stimulation and constraint-induced movement therapy. Evaluations involved analysis of functional independence, motor recovery, spasticity, gross motor function, and muscle strength. Results. A significant improvement in primary outcome (functional independence) after treatment in the premotor group followed by primary motor group and sham group was observed. The same pattern of improvement was highlighted among all secondary outcome measures regarding the superior performance of the premotor group over primary motor and sham groups. Conclusions. Premotor cortex can contribute to motor function in patients with severe functional disabilities in early stages of stroke. This study was registered in ClinicalTrials.gov database (NCT 02628561).

  18. Constraint-Induced Movement Therapy Combined with Transcranial Direct Current Stimulation over Premotor Cortex Improves Motor Function in Severe Stroke: A Pilot Randomized Controlled Trial

    Directory of Open Access Journals (Sweden)

    Suellen M. Andrade

    2017-01-01

    Full Text Available Objective. We compared the effects of transcranial direct current stimulation at different cortical sites (premotor and motor primary cortex combined with constraint-induced movement therapy for treatment of stroke patients. Design. Sixty patients were randomly distributed into 3 groups: Group A, anodal stimulation on premotor cortex and constraint-induced movement therapy; Group B, anodal stimulation on primary motor cortex and constraint-induced movement therapy; Group C, sham stimulation and constraint-induced movement therapy. Evaluations involved analysis of functional independence, motor recovery, spasticity, gross motor function, and muscle strength. Results. A significant improvement in primary outcome (functional independence after treatment in the premotor group followed by primary motor group and sham group was observed. The same pattern of improvement was highlighted among all secondary outcome measures regarding the superior performance of the premotor group over primary motor and sham groups. Conclusions. Premotor cortex can contribute to motor function in patients with severe functional disabilities in early stages of stroke. This study was registered in ClinicalTrials.gov database (NCT 02628561.

  19. Time and dose dependent effects of oxidative stress induced by cumene hydroperoxide in neuronal excitability of rat motor cortex neurons.

    Science.gov (United States)

    Pardillo-Díaz, R; Carrascal, L; Muñoz, M F; Ayala, A; Nunez-Abades, P

    2016-03-01

    It has been claimed that oxidative stress and the production of reactive oxygen radicals can contribute to neuron degeneration and might be one factor in the development of different neurological diseases. In our study, we have attempted to clarify how oxidative damage induces dose dependent changes in functional membrane properties of neurons by means of whole cell patch clamp techniques in brain slices from young adult rats. Our research demonstrates physiological changes in membrane properties of pyramidal motor cortex neurons exposed to 3 concentrations of cumene hydroperoxide (CH; 1, 10 and 100μM) during 30min. Results show that oxidative stress induced by CH evokes important changes, in a concentration and time dependent manner, in the neuronal excitability of motor cortex neurons of the rat: (i) Low concentration of the drug (1μM) already blocks inward rectifications (sag) and decreases action potential amplitude and gain, a drug concentration which has no effects on other neuronal populations, (ii) 10μM of CH depresses the excitability of pyramidal motor cortex neurons by decreasing input resistance, amplitude of the action potential, and gain and maximum frequency of the repetitive firing discharge, and (iii) 100μM completely blocks the capability to produce repetitive discharge of action potentials in all cells. Both larger drug concentrations and/or longer times of exposure to CH narrow the current working range. This happens because of the increase in the rheobase, and the reduction of the cancelation current. The effects caused by oxidative stress, including those produced by the level of lipid peroxidation, are practically irreversible and, this, therefore, indicates that neuroprotective agents should be administered at the first symptoms of alterations to membrane properties. In fact, the pre-treatment with melatonin, acting as an antioxidant, prevented the lipid peroxidation and the physiological changes induced by CH. Larger cells (as estimated

  20. The human dorsal premotor cortex facilitates the excitability of ipsilateral primary motor cortex via a short latency cortico-cortical route

    DEFF Research Database (Denmark)

    Groppa, Sergiu; Schlaak, Boris H; Münchau, Alexander

    2012-01-01

    (HAND) through specifically designed minicoils to selectively probe ipsilateral PMd-to-M1(HAND) connectivity in humans. A suprathreshold test stimulus (TS) was applied to M1(HAND) producing a motor evoked potential (MEP) of about 0.5 mV in the relaxed right first dorsal interosseus muscle (FDI......In non-human primates, invasive tracing and electrostimulation studies have identified strong ipsilateral cortico-cortical connections between dorsal premotor- (PMd) and the primary motor cortex (M1(HAND) ). Here, we applied dual-site transcranial magnetic stimulation (dsTMS) to left PMd and M1......). A subthreshold conditioning stimulus (CS) was given to PMd 2.0-5.2 ms after the TS at intensities of 50-, 70-, or 90% of TS. The CS to PMd facilitated the MEP evoked by TS over M1(HAND) at interstimulus intervals (ISI) of 2.4 or 2.8 ms. There was a second facilitatory peak at ISI of 4.4 ms. PMd-to-M1(HAND...

  1. Online feedback enhances early consolidation of motor sequence learning and reverses recall deficit from transcranial stimulation of motor cortex.

    Science.gov (United States)

    Wilkinson, Leonora; Steel, Adam; Mooshagian, Eric; Zimmermann, Trelawny; Keisler, Aysha; Lewis, Jeffrey D; Wassermann, Eric M

    2015-10-01

    Feedback and monetary reward can enhance motor skill learning, suggesting reward system involvement. Continuous theta burst (cTBS) transcranial magnetic stimulation (TMS) of the primary motor area (M1) disrupts processing, reduces excitability and impairs motor learning. To see whether feedback and reward can overcome the learning impairment associated with M1 cTBS, we delivered real or sham stimulation to two groups of participants before they performed a motor sequence learning task with and without feedback. Participants were trained on two intermixed sequences, one occurring 85% of the time (the "probable" sequence) and the other 15% of the time (the "improbable" sequence). We measured sequence learning as the difference in reaction time (RT) and error rate between probable and improbable trials (RT and error difference scores). Participants were also tested for sequence recall with the same indices of learning 60 min after cTBS. Real stimulation impaired initial sequence learning and sequence knowledge recall as measured by error difference scores and impaired sequence knowledge recall as measured by RT difference score. Relative to non-feedback learning, the introduction of feedback during sequence learning improved subsequent sequence knowledge recall indexed by RT difference score, in both real and sham stimulation groups and feedback reversed the RT difference score based sequence knowledge recall impairment from real cTBS that we observed in the non-feedback learning condition. Only the real cTBS group in the non-feedback condition showed no evidence of explicit sequence knowledge when tested at the end of the study. Feedback improves recall of implicit and explicit motor sequence knowledge and can protect sequence knowledge against the effect of M1 inhibition. Adding feedback and monetary reward/punishment to motor skill learning may help overcome retention impairments or accelerate training in clinical and other settings. Published by Elsevier Ltd.

  2. Loss of asymmetric spine synapses in prefrontal cortex of motor-asymptomatic, dopamine-depleted, cognitively impaired MPTP-treated monkeys.

    Science.gov (United States)

    Elsworth, John D; Leranth, Csaba; Redmond, D Eugene; Roth, Robert H

    2013-05-01

    Parkinson's disease is usually characterized as a movement disorder; however, cognitive abilities that are dependent on the prefrontal cortex decline at an early stage of the disease in most patients. The changes that underlie cognitive deficits in Parkinson's disease are not well understood. We hypothesize that reduced dopamine signalling in the prefrontal cortex in Parkinson's disease is a harbinger of detrimental synaptic changes in pyramidal neurons in the prefrontal cortex, whose function is necessary for normal cognition. Our previous data showed that monkeys exposed to the neurotoxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), but not exhibiting overt motor deficits (motor-asymptomatic), displayed cognitive deficits in prefrontal cortex-dependent tasks. The present results demonstrate that motor-asymptomatic MPTP-treated monkeys have a reduced dopamine concentration and a substantially lower number (50%) of asymmetric (excitatory) spine synapses in layer II/III, but not layer V, of the dorsolateral prefrontal cortex, compared to controls. In contrast, neither dopamine concentration nor asymmetric synapse number was altered in the entorhinal cortex of MPTP-treated monkeys. Together, these findings suggest that the number of asymmetric spine synapses on dendrites in the prefrontal cortex is dopamine-dependent and that the loss of synapses may be a morphological substrate of the cognitive deficits induced by a reduction in dopamine neurotransmission in this region.

  3. The Functional MR study of motor cortex%大脑皮层运动功能区的功能性磁共振成像

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Objective To observe the motor cortex activitie s on fMR imaging. Method The fMR study of motor cortex was performed in 15 normal volunteers using 1. 5T superconducting MR system, EPI pulse sequences, and BOLD fMR imaging. Six axial slices centered approxi- matdy at the precentral gyrus was obtained wit h or without both hands finger tapping motion under the operator instruction during the scanning. Pixels with significant signal differences ( P <0.0001) between with and without finger tapping were calculated as functional signal. The functional signal was superimposed on the corresponding T1 WI and brain water images Results The motor cortex ac tivities stimulated by finger tapping show as the area of increased signalintensity. The location of actwities is correspondent very well with the location of motor cortex. Most of activities present at the lateral aspect of precentral gyrus. In our group, the motion activities of left hemisphere is larger than that of right side in 10 volunteers, almost same sixe in 3 volunteers, smaller than that of right side in 1 volunteer. The fMR scan failed in 1 volunteer. Super- imposing the functional signals on the brain uner image may help to display the location of the activities. Conlusion fMR can show the location and size of motor cortex. It is simple, fast, noninvasive, and very convenient to implements with routine MR study.

  4. Plastic changes to dendritic spines on layer V pyramidal neurons are involved in the rectifying role of the prefrontal cortex during the fast period of motor learning.

    Science.gov (United States)

    González-Tapia, David; Martínez-Torres, Nestor I; Hernández-González, Marisela; Guevara, Miguel Angel; González-Burgos, Ignacio

    2016-02-01

    The prefrontal cortex participates in the rectification of information related to motor activity that favors motor learning. Dendritic spine plasticity is involved in the modifications of motor patterns that underlie both motor activity and motor learning. To study this association in more detail, adult male rats were trained over six days in an acrobatic motor learning paradigm and they were subjected to a behavioral evaluation on each day of training. Also, a Golgi-based morphological study was carried out to determine the spine density and the proportion of the different spine types. In the learning paradigm, the number of errors diminished as motor training progressed. Concomitantly, spine density increased on days 1 and 3 of training, particularly reflecting an increase in the proportion of thin (day 1), stubby (day 1) and branched (days 1, 2 and 5) spines. Conversely, mushroom spines were less prevalent than in the control rats on days 5 and 6, as were stubby spines on day 6, together suggesting that this plasticity might enhance motor learning. The increase in stubby spines on day 1 suggests a regulation of excitability related to the changes in synaptic input to the prefrontal cortex. The plasticity to thin spines observed during the first 3 days of training could be related to the active rectification induced by the information relayed to the prefrontal cortex -as the behavioral findings indeed showed-, which in turn could be linked to the lower proportion of mushroom and stubby spines seen in the last days of training.

  5. Repetitive transcranial magnetic stimulation of the primary motor cortex in the treatment of motor signs in Parkinson's disease: A quantitative review of the literature.

    Science.gov (United States)

    Zanjani, Anosha; Zakzanis, Konstantine K; Daskalakis, Zafiris J; Chen, Robert

    2015-05-01

    Parkinson's disease (PD) is a progressive disorder characterized by the emergence of motor deficits. In light of the voluminous and conflicting findings in the literature, the aim of the present quantitative review was to examine the effects of repetitive transcranial magnetic stimulation (rTMS) targeting the primary motor cortex (M1) in the treatment of motor signs in PD. Studies meeting inclusion criteria were analyzed using meta-analytic techniques and the Unified Parkinson's Disease Rating Scale (UPDRS) sections II and III were used as outcome measures. In order to determine the treatment effects of rTMS, the UPDRS II and III scores obtained at baseline, same day, to 1 day post rTMS treatment (short-term follow-up) and 1-month post stimulation (long-term follow-up) were compared between the active and sham rTMS groups. Additionally, the placebo effect was evaluated as the changes in UPDRS III scores in the sham rTMS groups. A placebo effect was not demonstrated, because sham rTMS did not improve motor signs as measured by UPDRS III. Compared with sham rTMS, active rTMS targeting the M1 significantly improved UPDRS III scores at the short-term follow-up (Cohen's d of 0.27, UPDRS III score improvement of 3.8 points). When the long-term follow-up UPDRS III scores were compared with baseline scores, the standardized effect size between active and sham rTMS did not reach significance. However, this translated into a significant nonstandardized 6.3-point improvement on the UPDRS III. No significant improvement in the UPDRS II was found. rTMS over the M1 may improve motor signs. Further studies are needed to provide a definite conclusion.

  6. Low-frequency rTMS inhibitory effects in the primary motor cortex: Insights from TMS-evoked potentials.

    Science.gov (United States)

    Casula, Elias P; Tarantino, Vincenza; Basso, Demis; Arcara, Giorgio; Marino, Giuliana; Toffolo, Gianna Maria; Rothwell, John C; Bisiacchi, Patrizia S

    2014-09-01

    The neuromodulatory effects of repetitive transcranial magnetic stimulation (rTMS) have been mostly investigated by peripheral motor-evoked potentials (MEPs). New TMS-compatible EEG systems allow a direct investigation of the stimulation effects through the analysis of TMS-evoked potentials (TEPs). We investigated the effects of 1-Hz rTMS over the primary motor cortex (M1) of 15 healthy volunteers on TEP evoked by single pulse TMS over the same area. A second experiment in which rTMS was delivered over the primary visual cortex (V1) of 15 healthy volunteers was conducted to examine the spatial specificity of the effects. Single-pulse TMS evoked four main components: P30, N45, P60 and N100. M1-rTMS resulted in a significant decrease of MEP amplitude and in a significant increase of P60 and N100 amplitude. There was no effect after V1-rTMS. 1-Hz rTMS appears to increase the amount of inhibition following a TMS pulse, as demonstrated by the higher N100 and P60, which are thought to originate from GABAb-mediated inhibitory post-synaptic potentials. Our results confirm the reliability of the TMS-evoked N100 as a marker of cortical inhibition and provide insight into the neuromodulatory effects of 1-Hz rTMS. The present finding could be of relevance for therapeutic and diagnostic purposes.

  7. Temporal dynamics of motor cortex excitability during perception of natural emotional scenes

    NARCIS (Netherlands)

    Borgomaneri, Sara; Gazzola, Valeria; Avenanti, Alessio

    2014-01-01

    Although it is widely assumed that emotions prime the body for action, the effects of visual perception of natural emotional scenes on the temporal dynamics of the human motor system have scarcely been investigated. Here, we used single-pulse transcranial magnetic stimulation (TMS) to assess motor e

  8. Temporal dynamics of motor cortex excitability during perception of natural emotional scenes

    NARCIS (Netherlands)

    Borgomaneri, Sara; Gazzola, V.; Avenanti, Alessio

    2014-01-01

    Although it is widely assumed that emotions prime the body for action, the effects of visual perception of natural emotional scenes on the temporal dynamics of the human motor system have scarcely been investigated. Here, we used single-pulse transcranial magnetic stimulation (TMS) to assess motor

  9. Partially non-linear stimulation intensity-dependent effects of direct current stimulation on motor cortex excitability in humans.

    Science.gov (United States)

    Batsikadze, G; Moliadze, V; Paulus, W; Kuo, M-F; Nitsche, M A

    2013-04-01

    Transcranial direct current stimulation (tDCS) of the human motor cortex at an intensity of 1 mA with an electrode size of 35 cm(2) has been shown to induce shifts of cortical excitability during and after stimulation. These shifts are polarity-specific with cathodal tDCS resulting in a decrease and anodal stimulation in an increase of cortical excitability. In clinical and cognitive studies, stronger stimulation intensities are used frequently, but their physiological effects on cortical excitability have not yet been explored. Therefore, here we aimed to explore the effects of 2 mA tDCS on cortical excitability. We applied 2 mA anodal or cathodal tDCS for 20 min on the left primary motor cortex of 14 healthy subjects. Cathodal tDCS at 1 mA and sham tDCS for 20 min was administered as control session in nine and eight healthy subjects, respectively. Motor cortical excitability was monitored by transcranial magnetic stimulation (TMS)-elicited motor-evoked potentials (MEPs) from the right first dorsal interosseous muscle. Global corticospinal excitability was explored via single TMS pulse-elicited MEP amplitudes, and motor thresholds. Intracortical effects of stimulation were obtained by cortical silent period (CSP), short latency intracortical inhibition (SICI) and facilitation (ICF), and I wave facilitation. The above-mentioned protocols were recorded both before and immediately after tDCS in randomized order. Additionally, single-pulse MEPs, motor thresholds, SICI and ICF were recorded every 30 min up to 2 h after stimulation end, evening of the same day, next morning, next noon and next evening. Anodal as well as cathodal tDCS at 2 mA resulted in a significant increase of MEP amplitudes, whereas 1 mA cathodal tDCS decreased corticospinal excitability. A significant shift of SICI and ICF towards excitability enhancement after both 2 mA cathodal and anodal tDCS was observed. At 1 mA, cathodal tDCS reduced single-pulse TMS-elicited MEP amplitudes and shifted SICI

  10. Differential effects of primary motor cortex and cerebellar transcranial direct current stimulation on motor learning in healthy individuals: A randomized double-blind sham-controlled study.

    Science.gov (United States)

    Ehsani, F; Bakhtiary, A H; Jaberzadeh, S; Talimkhani, A; Hajihasani, A

    2016-11-01

    The purpose of study was to compare the effect of primary motor cortex (M1) and cerebellar anodal transcranial direct current stimulation (a-tDCS) on online and offline motor learning in healthy individuals. Fifty-nine healthy volunteers were randomly divided into three groups (n=20 in two experimental groups and n=19 in sham-control group). One experimental group received M1a-tDCSand another received cerebellar a-tDCS. The main outcome measure were response time (RT) and number of errors during serial response time test (SRTT) which were assessed prior, 35min and 48h after the interventions. Reduction of response time (RT) and error numbers at last block of the test compared to the first block was considered online learning. Comparison of assessments during retention tests was considered as short-term and long-term offline learning. Online RT reduction was not different among groups (P>0.05), while online error reduction was significantly greater in cerebellar a-tDCS than sham-control group (Plearning as compared to sham tDCS (Pgroup (Plearning and M1a-tDCS has more effect on short-term offline learning, both M1 and cerebellar a-tDCS can be used as a boosting technique for improvement of offline motor learning in healthy individuals. Crown Copyright © 2016. Published by Elsevier Ireland Ltd. All rights reserved.

  11. Transcranial magnetic stimulation probes the excitability of the primary motor cortex: A framework to account for the facilitating effects of acute whole-body exercise on motor processes

    Directory of Open Access Journals (Sweden)

    Karen Davranche

    2015-03-01

    Full Text Available The effects of exercise on decision-making performance have been studied using a wide variety of cognitive tasks and exercise interventions. Although the current literature supports a beneficial influence of acute exercise on cognitive performance, the mechanisms underlying this phenomenon have not yet been elucidated. We review studies that used single-pulse transcranial magnetic stimulation (TMS to probe the excitability of motor structures during whole-body exercise and present a framework to account for the facilitating effects of acute exercise on motor processes. Recent results suggest that, even in the absence of fatigue, the increase in corticospinal excitability classically reported during submaximal and exhausting exercises may be accompanied by a reduction in intracortical inhibition. We propose that reduced intracortical inhibition elicits an adaptive central mechanism that counteracts the progressive reduction in muscle responsiveness caused by peripheral fatigue. Such a reduction would render the motor cortex more sensitive to upstream influences, thus causing increased corticospinal excitability. Furthermore, reduction of intracortical inhibition may account for the more efficient descending drive and for the improvement of reaction time performance during exercise. The adaptive modulation in intracortical inhibition could be implemented through a general increase in reticular activation that would further account for enhanced sensory sensitivity.

  12. The Effects of Long Duration Bed Rest on Functional Mobility and Balance: Relationship to Resting State Motor Cortex Connectivity

    Science.gov (United States)

    Erdeniz, B.; Koppelmans, V.; Bloomberg, J. J.; Kofman, I. S.; DeDios, Y. E.; Riascos-Castaneda, R. F.; Wood, S. J.; Mulavara, A. P.; Seidler, R. D.

    2014-01-01

    NASA offers researchers from a variety of backgrounds the opportunity to study bed rest as an experimental analog for space flight. Extended exposure to a head-down tilt position during long duration bed rest can resemble many of the effects of a low-gravity environment such as reduced sensory inputs, body unloading and increased cephalic fluid distribution. The aim of our study is to a) identify changes in brain function that occur with prolonged bed rest and characterize their recovery time course; b) assess whether and how these changes impact behavioral and neurocognitive performance. Thus far, we completed data collection from six participants that include task based and resting state fMRI. The data have been acquired through the bed rest facility located at the University of Texas Medical Branch (Galveston, TX). Subjects remained in bed with their heads tilted down 6 degrees below their feet for 70 consecutive days. Behavioral measures and neuroimaging assessments were obtained at seven time points: a) 7 and 12 days before bed rest; b) 7, 30, and 65 days during bed rest; and c) 7 and 12 days after bed rest. Functional connectivity magnetic resonance imaging (FcMRI) analysis was performed to assess the connectivity of motor cortex in and out of bed rest. We found a decrease in motor cortex connectivity with vestibular cortex and the cerebellum from pre bed rest to in bed rest. We also used a battery of behavioral measures including the functional mobility test and computerized dynamic posturography collected before and after bed rest. We will report the preliminary results of analyses relating brain and behavior changes. Furthermore, we will also report the preliminary results of a spatial working memory task and vestibular stimulation during in and out of bed rest.

  13. Differential expression of secreted phosphoprotein 1 in the motor cortex among primate species and during postnatal development and functional recovery.

    Directory of Open Access Journals (Sweden)

    Tatsuya Yamamoto

    Full Text Available We previously reported that secreted phosphoprotein 1 (SPP1 mRNA is expressed in neurons whose axons form the corticospinal tract (CST of the rhesus macaque, but not in the corresponding neurons of the marmoset and rat. This suggests that SPP1 expression is involved in the functional or structural specialization of highly developed corticospinal systems in certain primate species. To further examine this hypothesis, we evaluated the expression of SPP1 mRNA in the motor cortex from three viewpoints: species differences, postnatal development, and functional/structural changes of the CST after a lesion of the lateral CST (l-CST at the mid-cervical level. The density of SPP1-positive neurons in layer V of the primary motor cortex (M1 was much greater in species with highly developed corticospinal systems (i.e., rhesus macaque, capuchin monkey, and humans than in those with less developed corticospinal systems (i.e., squirrel monkey, marmoset, and rat. SPP1-positive neurons in the macaque monkey M1 increased logarithmically in layer V during postnatal development, following a time course consistent with the increase in conduction velocity of the CST. After an l-CST lesion, SPP1-positive neurons increased in layer V of the ventral premotor cortex, in which compensatory changes in CST function/structure may occur, which positively correlated with the extent of finger dexterity recovery. These results further support the concept that the expression of SPP1 may reflect functional or structural specialization of highly developed corticospinal systems in certain primate species.

  14. Thinking about Eating Food Activates Visual Cortex with Reduced Bilateral Cerebellar Activation in Females with Anorexia Nervosa: An fMRI Study

    Science.gov (United States)

    Brooks, Samantha J.; O'Daly, Owen; Uher, Rudolf; Friederich, Hans-Christoph; Giampietro, Vincent; Brammer, Michael; Williams, Steven C. R.; Schiöth, Helgi B.; Treasure, Janet; Campbell, Iain C.

    2012-01-01

    Background Women with anorexia nervosa (AN) have aberrant cognitions about food and altered activity in prefrontal cortical and somatosensory regions to food images. However, differential effects on the brain when thinking about eating food between healthy women and those with AN is unknown. Methods Functional magnetic resonance imaging (fMRI) examined neural activation when 42 women thought about eating the food shown in images: 18 with AN (11 RAN, 7 BPAN) and 24 age-matched controls (HC). Results Group contrasts between HC and AN revealed reduced activation in AN in the bilateral cerebellar vermis, and increased activation in the right visual cortex. Preliminary comparisons between AN subtypes and healthy controls suggest differences in cortical and limbic regions. Conclusions These preliminary data suggest that thinking about eating food shown in images increases visual and prefrontal cortical neural responses in females with AN, which may underlie cognitive biases towards food stimuli and ruminations about controlling food intake. Future studies are needed to explicitly test how thinking about eating activates restraint cognitions, specifically in those with restricting vs. binge-purging AN subtypes. PMID:22479499

  15. Thinking about eating food activates visual cortex with reduced bilateral cerebellar activation in females with anorexia nervosa: an fMRI study.

    Directory of Open Access Journals (Sweden)

    Samantha J Brooks

    Full Text Available BACKGROUND: Women with anorexia nervosa (AN have aberrant cognitions about food and altered activity in prefrontal cortical and somatosensory regions to food images. However, differential effects on the brain when thinking about eating food between healthy women and those with AN is unknown. METHODS: Functional magnetic resonance imaging (fMRI examined neural activation when 42 women thought about eating the food shown in images: 18 with AN (11 RAN, 7 BPAN and 24 age-matched controls (HC. RESULTS: Group contrasts between HC and AN revealed reduced activation in AN in the bilateral cerebellar vermis, and increased activation in the right visual cortex. Preliminary comparisons between AN subtypes and healthy controls suggest differences in cortical and limbic regions. CONCLUSIONS: These preliminary data suggest that thinking about eating food shown in images increases visual and prefrontal cortical neural responses in females with AN, which may underlie cognitive biases towards food stimuli and ruminations about controlling food intake. Future studies are needed to explicitly test how thinking about eating activates restraint cognitions, specifically in those with restricting vs. binge-purging AN subtypes.

  16. Motor cortex-periaqueductal gray-spinal cord neuronal circuitry may involve in modulation of nociception: a virally mediated transsynaptic tracing study in spinally transected transgenic mouse model.

    Directory of Open Access Journals (Sweden)

    Da-Wei Ye

    Full Text Available Several studies have shown that motor cortex stimulation provided pain relief by motor cortex plasticity and activating descending inhibitory pain control systems. Recent evidence indicated that the melanocortin-4 receptor (MC4R in the periaqueductal gray played an important role in neuropathic pain. This study was designed to assess whether MC4R signaling existed in motor cortex-periaqueductal gray-spinal cord neuronal circuitry modulated the activity of sympathetic pathway by a virally mediated transsynaptic tracing study. Pseudorabies virus (PRV-614 was injected into the left gastrocnemius muscle in adult male MC4R-green fluorescent protein (GFP transgenic mice (n = 15. After a survival time of 4-6 days, the mice (n = 5 were randomly assigned to humanely sacrifice, and spinal cords and brains were removed and sectioned, and processed for PRV-614 visualization. Neurons involved in the efferent control of the left gastrocnemius muscle were identified following visualization of PRV-614 retrograde tracing. The neurochemical phenotype of MC4R-GFP-positive neurons was identified using fluorescence immunocytochemical labeling. PRV-614/MC4R-GFP dual labeled neurons were detected in spinal IML, periaqueductal gray and motor cortex. Our findings support the hypothesis that MC4R signaling in motor cortex-periaqueductal gray-spinal cord neural pathway may participate in the modulation of the melanocortin-sympathetic signaling and contribute to the descending modulation of nociceptive transmission, suggesting that MC4R signaling in motor cortex-periaqueductal gray-spinal cord neural pathway may modulate the activity of sympathetic outflow sensitive to nociceptive signals.

  17. Associative plasticity in the human motor cortex is enhanced by concurrently targeting separate muscle representations with excitatory and inhibitory protocols.

    Science.gov (United States)

    Kamke, Marc R; Nydam, Abbey S; Sale, Martin V; Mattingley, Jason B

    2016-04-01

    Paired associative stimulation (PAS) induces changes in the excitability of human sensorimotor cortex that outlast the procedure. PAS typically involves repeatedly pairing stimulation of a peripheral nerve that innervates an intrinsic hand muscle with transcranial magnetic stimulation over the representation of that muscle in the primary motor cortex. Depending on the timing of the stimuli (interstimulus interval of 25 or 10 ms), PAS leads to either an increase (PAS25) or a decrease (PAS10) in excitability. Both protocols, however, have been associated with an increase in excitability of nearby muscle representations not specifically targeted by PAS. Based on these spillover effects, we hypothesized that an additive, excitability-enhancing effect of PAS25 applied to one muscle representation may be produced by simultaneously applying PAS25 or PAS10 to a nearby representation. In different experiments prototypical PAS25 targeting the left thumb representation [abductor pollicis brevis (APB)] was combined with either PAS25 or PAS10 applied to the left little finger representation [abductor digiti minimi (ADM)] or, in a control experiment, with PAS10 also targeting the APB. In an additional control experiment PAS10 targeted both representations. The plasticity effects were quantified by measuring the amplitude of motor evoked potentials (MEPs) recorded before and after PAS. As expected, prototypical PAS25 was associated with an increase in MEP amplitude in the APB muscle. This effect was enhanced when PAS also targeted the ADM representation but only when a different interstimulus timing (PAS10) was used. These results suggest that PAS-induced plasticity is modified by concurrently targeting separate motor cortical representations with excitatory and inhibitory protocols.

  18. Bidirectional control of a one-dimensional robotic actuator by operant conditioning of a single unit in rat motor cortex

    Directory of Open Access Journals (Sweden)

    Pierre-Jean eArduin

    2014-07-01

    Full Text Available The design of efficient neuroprosthetic devices has become a major challenge for the long-term goal of restoring autonomy to motor-impaired patients. One approach for brain control of actuators consists in decoding the activity pattern obtained by simultaneously recording large neuronal ensembles in order to predict in real-time the subject’s intention, and move the prosthesis accordingly. An alternative way is to assign the output of one or a few neurons by operant conditioning to control the prosthesis with rules defined by the experimenter, and rely on the functional adaptation of these neurons during learning to reach the desired behavioral outcome. Here, several motor cortex neurons were recorded simultaneously in head-fixed awake rats and were conditioned, one at a time, to modulate their firing rate up and down in order to control the speed and direction of a one-dimensional actuator carrying a water bottle. The goal was to maintain the bottle in front of the rat’s mouth, allowing it to drink. After learning, all conditioned neurons modulated their firing rate, effectively controlling the bottle position so that the drinking time was increased relative to chance. The mean firing rate averaged over all bottle trajectories depended non-linearly on position, so that the mouth position operated as an attractor. Some modifications of mean firing rate were observed in the surrounding neurons, but to a lesser extent. Notably, the conditioned neuron reacted faster and led to a better control than surrounding neurons, as calculated by using the activity of those neurons to generate simulated bottle trajectories. Our study demonstrates the feasibility, even in the rodent, of using a motor cortex neuron to control a prosthesis in real-time bidirectionally. The learning process includes modifications of the activity of neighboring cortical neurons, while the conditioned neuron selectively leads the activity patterns associated with the prosthesis

  19. A Small Motor Cortex