scholarly journals Human motor fatigability as evoked by repetitive movements results from a gradual breakdown of surround inhibition

2019 ◽  
Author(s):  
Marc Bächinger ◽  
Rea Lehner ◽  
Felix Thomas ◽  
Samira Hanimann ◽  
Joshua Henk Balsters ◽  
...  
Keyword(s):  
Primary Motor Cortex ◽  
Extended Period ◽  
Movement Speed ◽  
Central Component ◽  
Surround Inhibition ◽  
Link Performance ◽  
Motor Network ◽  
Antagonistic Muscle ◽  
Human Motor ◽  
Muscle Groups

SummaryMotor fatigability emerges when demanding tasks are executed over an extended period of time. Here, we used repetitive low-force movements that cause a gradual reduction in movement speed (or “motor slowing”) to study the central component of fatigability in healthy adults. We show that motor slowing is associated with a gradual increase of net excitability in the motor network and, specifically, in primary motor cortex (M1), which results from overall disinhibition. Importantly, we link performance decrements to a breakdown of surround inhibition in M1, which is associated with high coactivation of antagonistic muscle groups. This is consistent with the model that a loss of inhibitory control might broaden the tuning of population vectors such that movement patterns become more variable, ill-timed and effortful. We propose that the release of inhibition in M1 is an important mechanism underpinning motor fatigability and, potentially, also pathological fatigue as frequently observed in patients with brain disorders.

scholarly journals Human motor fatigability as evoked by repetitive movements results from a gradual breakdown of surround inhibition

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Marc Bächinger ◽  
Rea Lehner ◽  
Felix Thomas ◽  
Samira Hanimann ◽  
Joshua Balsters ◽  
...  
Keyword(s):  
Primary Motor Cortex ◽  
Extended Period ◽  
Movement Speed ◽  
Central Component ◽  
Surround Inhibition ◽  
Link Performance ◽  
Motor Network ◽  
Antagonistic Muscle ◽  
Human Motor ◽  
Muscle Groups

Motor fatigability emerges when demanding tasks are executed over an extended period of time. Here, we used repetitive low-force movements that cause a gradual reduction in movement speed (or ‘motor slowing’) to study the central component of fatigability in healthy adults. We show that motor slowing is associated with a gradual increase of net excitability in the motor network and, specifically, in primary motor cortex (M1), which results from overall disinhibition. Importantly, we link performance decrements to a breakdown of surround inhibition in M1, which is associated with high coactivation of antagonistic muscle groups. This is consistent with the model that a loss of inhibitory control might broaden the tuning of population vectors such that movement patterns become more variable, ill-timed and effortful. We propose that the release of inhibition in M1 is an important mechanism underpinning motor fatigability and, potentially, also pathological fatigue as frequently observed in patients with brain disorders.

scholarly journals Periinfarct rewiring supports recovery after primary motor cortex stroke

2021 ◽  
pp. 0271678X2110029
Author(s):  
Mitsouko van Assche ◽  
Elisabeth Dirren ◽  
Alexia Bourgeois ◽  
Andreas Kleinschmidt ◽  
Jonas Richiardi ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Spatial Scales ◽  
Premotor Cortex ◽  
Core Network ◽  
Small Spatial Scale ◽  
The Core ◽  
Hand Dexterity ◽  
Motor Network ◽  
Motor Improvement

After stroke restricted to the primary motor cortex (M1), it is uncertain whether network reorganization associated with recovery involves the periinfarct or more remote regions. We studied 16 patients with focal M1 stroke and hand paresis. Motor function and resting-state MRI functional connectivity (FC) were assessed at three time points: acute (<10 days), early subacute (3 weeks), and late subacute (3 months). FC correlates of recovery were investigated at three spatial scales, (i) ipsilesional non-infarcted M1, (ii) core motor network (M1, premotor cortex (PMC), supplementary motor area (SMA), and primary somatosensory cortex), and (iii) extended motor network including all regions structurally connected to the upper limb representation of M1. Hand dexterity was impaired only in the acute phase ( P = 0.036). At a small spatial scale, clinical recovery was more frequently associated with connections involving ipsilesional non-infarcted M1 (Odds Ratio = 6.29; P = 0.036). At a larger scale, recovery correlated with increased FC strength in the core network compared to the extended motor network (rho = 0.71; P = 0.006). These results suggest that FC changes associated with motor improvement involve the perilesional M1 and do not extend beyond the core motor network. Core motor regions, and more specifically ipsilesional non-infarcted M1, could hence become primary targets for restorative therapies.

scholarly journals The Functional Role of Thalamocortical Coupling in the Human Motor Network

2019 ◽  
Vol 39 (41) ◽  
pp. 8124-8134 ◽  
Author(s):  
Enrico Opri ◽  
Stephanie Cernera ◽  
Michael S. Okun ◽  
Kelly D. Foote ◽  
Aysegul Gunduz
Keyword(s):  
Functional Role ◽  
Motor Network ◽  
Human Motor

scholarly journals High Gamma and Beta Temporal Interference Stimulation in the Human Motor Cortex Improves Motor Functions

2022 ◽  
Vol 15 ◽  
Author(s):  
Ru Ma ◽  
Xinzhao Xia ◽  
Wei Zhang ◽  
Zhuo Lu ◽  
Qianying Wu ◽  
...  
Keyword(s):  
Reaction Time ◽  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Reaction Time Task ◽  
Promoting Effect ◽  
Motor Functions ◽  
Human Motor Cortex ◽  
Time Task ◽  
Motor Cortex Excitability ◽  
Human Motor

Background: Temporal interference (TI) stimulation is a new technique of non-invasive brain stimulation. Envelope-modulated waveforms with two high-frequency carriers can activate neurons in target brain regions without stimulating the overlying cortex, which has been validated in mouse brains. However, whether TI stimulation can work on the human brain has not been elucidated.Objective: To assess the effectiveness of the envelope-modulated waveform of TI stimulation on the human primary motor cortex (M1).Methods: Participants attended three sessions of 30-min TI stimulation during a random reaction time task (RRTT) or a serial reaction time task (SRTT). Motor cortex excitability was measured before and after TI stimulation.Results: In the RRTT experiment, only 70 Hz TI stimulation had a promoting effect on the reaction time (RT) performance and excitability of the motor cortex compared to sham stimulation. Meanwhile, compared with the sham condition, only 20 Hz TI stimulation significantly facilitated motor learning in the SRTT experiment, which was significantly positively correlated with the increase in motor evoked potential.Conclusion: These results indicate that the envelope-modulated waveform of TI stimulation has a significant promoting effect on human motor functions, experimentally suggesting the effectiveness of TI stimulation in humans for the first time and paving the way for further explorations.

scholarly journals Local GABA concentration is related to network-level resting functional connectivity

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Charlotte J Stagg ◽  
Velicia Bachtiar ◽  
Ugwechi Amadi ◽  
Christel A Gudberg ◽  
Andrei S Ilie ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Resting State ◽  
Primary Motor Cortex ◽  
Empirical Studies ◽  
Network Connectivity ◽  
Resting State Fmri ◽  
Resonance Spectroscopy ◽  
Resting State Networks ◽  
Inhibitory Neurotransmitter ◽  
Motor Network

Anatomically plausible networks of functionally inter-connected regions have been reliably demonstrated at rest, although the neurochemical basis of these ‘resting state networks’ is not well understood. In this study, we combined magnetic resonance spectroscopy (MRS) and resting state fMRI and demonstrated an inverse relationship between levels of the inhibitory neurotransmitter GABA within the primary motor cortex (M1) and the strength of functional connectivity across the resting motor network. This relationship was both neurochemically and anatomically specific. We then went on to show that anodal transcranial direct current stimulation (tDCS), an intervention previously shown to decrease GABA levels within M1, increased resting motor network connectivity. We therefore suggest that network-level functional connectivity within the motor system is related to the degree of inhibition in M1, a major node within the motor network, a finding in line with converging evidence from both simulation and empirical studies.

S4-1 Surround inhibition in the human motor system

2010 ◽  
Vol 121 ◽  
pp. S14
Author(s):  
Y.H. Sohn ◽  
H.-W. Shin ◽  
S.Y. Kang ◽  
M. Hallett
Keyword(s):  
Motor System ◽  
Surround Inhibition ◽  
Human Motor

scholarly journals THE ANALYSIS OF NEUROMUSCULAR MECHANISMS IN CHITON

1920 ◽  
Vol 2 (6) ◽  
pp. 627-634 ◽  
Author(s):  
W. J. Crozier
Keyword(s):  
Early Stage ◽  
Ventral Surface ◽  
Reciprocal Inhibition ◽  
Relative Strength ◽  
The Body ◽  
Antagonistic Muscle ◽  
Flexor Muscles ◽  
Neuromuscular Apparatus ◽  
Neuromuscular Responses ◽  
Muscle Groups

1. The degree of curvature of the body and of the girdle of a Chiton is determined by the activity of antagonistic muscle groups. At a certain, early stage in the strychninization of a Chiton the reciprocal inhibition involved in the natural use of these muscle groups is reversed, such that extensor muscles, rather than, as normally, flexor muscles, contract as the result of stimulation. This condition involves a reversal, under strychnine, of the normally positive stereotropism of the foot, and of the usual response of the mollusk to an increased illumination of its ventral surface. Strychnine reversal of this character is not a matter of the relative strength of the opposed muscle groups, for the flexor muscles are the more powerful and are the ones always shortened in tetanic contraction. 2. Nicotine, in contrast to strychnine, primarily induces contraction of flexor muscles. Its effects, moreover, are in a degree selective, being notably exerted on "cerebral" nervous structures. Curare is devoid of characteristic action on the neuromuscular responses of Chiton. 3. The chemical organization of the neuromuscular organs of Chiton, as far as revealed by these tests, corresponds to a more simple condition than is inferred for gastropods. In particular, the behavior with respect to curare resembles more that of the neuromuscular apparatus of flatworms.

scholarly journals The response of the anterior striatum during adult human vocal learning

2014 ◽  
Vol 112 (4) ◽  
pp. 792-801 ◽  
Author(s):  
Anna J. Simmonds ◽  
Robert Leech ◽  
Paul Iverson ◽  
Richard J. S. Wise
Keyword(s):  
Vocal Learning ◽  
Central Component ◽  
The Novel ◽  
Adult Human ◽  
Articulatory Movements ◽  
Adult Participants ◽  
Fmri Study ◽  
Human Motor ◽  
And Performance ◽  
Improved Accuracy

Research on mammals predicts that the anterior striatum is a central component of human motor learning. However, because vocalizations in most mammals are innate, much of the neurobiology of human vocal learning has been inferred from studies on songbirds. Essential for song learning is a pathway, the homolog of mammalian cortical-basal ganglia “loops,” which includes the avian striatum. The present functional magnetic resonance imaging (fMRI) study investigated adult human vocal learning, a skill that persists throughout life, albeit imperfectly given that late-acquired languages are spoken with an accent. Monolingual adult participants were scanned while repeating novel non-native words. After training on the pronunciation of half the words for 1 wk, participants underwent a second scan. During scanning there was no external feedback on performance. Activity declined sharply in left and right anterior striatum, both within and between scanning sessions, and this change was independent of training and performance. This indicates that adult speakers rapidly adapt to the novel articulatory movements, possibly by using motor sequences from their native speech to approximate those required for the novel speech sounds. Improved accuracy correlated only with activity in motor-sensory perisylvian cortex. We propose that future studies on vocal learning, using different behavioral and pharmacological manipulations, will provide insights into adult striatal plasticity and its potential for modification in both educational and clinical contexts.

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