scholarly journals Corticospinal correlates of fast and slow adaptive processes in motor learning

2018 ◽  
Vol 120 (4) ◽  
pp. 2011-2019 ◽  
Author(s):  
Adjmal M. E. Sarwary ◽  
Miles Wischnewski ◽  
Dennis J. L. G. Schutter ◽  
Luc P. J. Selen ◽  
W. Pieter Medendorp
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Motor Cortex ◽  
Motor Learning ◽  
Magnetic Stimulation ◽  
Corticospinal Excitability ◽  
Behavioral Observations ◽  
Adaptive Processes ◽  
Adaptation Processes ◽  
Adaptation Task ◽  
Adaptation Model

Recent computational theories and behavioral observations suggest that motor learning is supported by multiple adaptation processes, operating on different timescales, but direct neural evidence is lacking. We tested this hypothesis by applying transcranial magnetic stimulation over motor cortex in 16 human subjects during a validated reach adaptation task. Motor-evoked potentials (MEPs) and cortical silent periods (CSPs) were recorded from the biceps brachii to assess modulations of corticospinal excitability as indices for corticospinal plasticity. Guided by a two-state adaptation model, we show that the MEP reflects an adaptive process that learns quickly but has poor retention, while the CSP correlates with a process that responds more slowly but retains information well. These results provide a physiological link between models of motor learning and distinct changes in corticospinal excitability. Our findings support the relationship between corticospinal gain modulations and the adaptive processes in motor learning. NEW & NOTEWORTHY Computational theories and behavioral observations suggest that motor learning is supported by multiple adaptation processes, but direct neural evidence is lacking. We tested this hypothesis by applying transcranial magnetic stimulation over human motor cortex during a reach adaptation task. Guided by a two-state adaptation model, we show that the motor-evoked potential reflects a process that adapts and decays quickly, whereas the cortical silent period reflects slow adaptation and decay.

Whole-hand water flow stimulation increases motor cortical excitability: a study of transcranial magnetic stimulation and movement-related cortical potentials

2015 ◽  
Vol 113 (3) ◽  
pp. 822-833 ◽  
Author(s):  
Daisuke Sato ◽  
Koya Yamashiro ◽  
Hideaki Onishi ◽  
Baba Yasuhiro ◽  
Yoshimitsu Shimoyama ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Motor Cortex ◽  
Water Flow ◽  
Magnetic Stimulation ◽  
Cortical Activity ◽  
Corticospinal Excitability ◽  
Afferent Stimulation ◽  
Intracortical Circuits ◽  
Before And After ◽  
Flow Stimulation

Previous studies examining the influence of afferent stimulation on corticospinal excitability have demonstrated that the intensity of afferent stimulation and the nature of the afferents targeted (cutaneous/proprioceptive) determine the effects. In this study, we assessed the effects of whole-hand water immersion (WI) and water flow stimulation (WF) on corticospinal excitability and intracortical circuits by measuring motor evoked potential (MEP) recruitment curves and conditioned MEP amplitudes. We further investigated whether whole-hand WF modulated movement-related cortical activity. Ten healthy subjects participated in three experiments, comprising the immersion of participants' right hands with (whole-hand WF) or without (whole-hand WI) water flow, and no immersion (control). We evaluated MEP recruitment curves produced by a single transcranial magnetic stimulation (TMS) pulse at increasing stimulus intensities, short-interval intracortical inhibition (SICI), and intracortical facilitation (ICF) using the paired TMS technique before and after 15 min of intervention. Movement-related cortical potentials (MRCPs) were evaluated to examine primary motor cortex, supplementary motor area, and somatosensory cortex excitability upon movement before and after whole-hand WF. After whole-hand WF, the slope of the MEP recruitment curve significantly increased, whereas SICI decreased and ICF increased in the contralateral motor cortex. The amplitude of the Bereitschaftspotential, negative slope, and motor potential of MRCPs significantly increased after whole-hand WF. We demonstrated that whole-hand WF increased corticospinal excitability, decreased SICI, and increased ICF, although whole-hand WI did not change corticospinal excitability and intracortical circuits. Whole-hand WF modulated movement-related cortical activity, increasing motor cortex activation for the planning and execution of voluntary movements.

scholarly journals Effect of graded hypoxia on supraspinal contributions to fatigue with unilateral knee-extensor contractions

2010 ◽  
Vol 109 (6) ◽  
pp. 1842-1851 ◽  
Author(s):  
Stuart Goodall ◽  
Emma Z. Ross ◽  
Lee M. Romer
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Motor Cortex ◽  
Maximal Voluntary Contraction ◽  
Magnetic Stimulation ◽  
Voluntary Contraction ◽  
Corticospinal Excitability ◽  
Voluntary Activation ◽  
Severe Hypoxia ◽  
Knee Extensors ◽  
Moderate Hypoxia

Supraspinal fatigue, defined as an exercise-induced decline in force caused by suboptimal output from the motor cortex, accounts for over one-quarter of the force loss after fatiguing contractions of the knee extensors in normoxia. We tested the hypothesis that the relative contribution of supraspinal fatigue would be elevated with increasing severities of acute hypoxia. On separate days, 11 healthy men performed sets of intermittent, isometric, quadriceps contractions at 60% maximal voluntary contraction to task failure in normoxia (inspired O2 fraction/arterial O2 saturation = 0.21/98%), mild hypoxia (0.16/93%), moderate hypoxia (0.13/85%), and severe hypoxia (0.10/74%). Electrical stimulation of the femoral nerve was performed to assess neuromuscular transmission and contractile properties of muscle fibers. Transcranial magnetic stimulation was delivered to the motor cortex to quantify corticospinal excitability and voluntary activation. After 10 min of breathing the test gas, neuromuscular function and cortical voluntary activation prefatigue were unaffected in any condition. The fatigue protocol resulted in ∼30% declines in maximal voluntary contraction force in all conditions, despite differences in time-to-task failure (24.7 min in normoxia vs. 15.9 min in severe hypoxia, P < 0.05). Potentiated quadriceps twitch force declined in all conditions, but the decline in severe hypoxia was less than that in normoxia ( P < 0.05). Cortical voluntary activation also declined in all conditions, but the deficit in severe hypoxia exceeded that in normoxia ( P < 0.05). The additional central fatigue in severe hypoxia was not due to altered corticospinal excitability, as electromyographic responses to transcranial magnetic stimulation were unchanged. Results indicate that peripheral mechanisms of fatigue contribute relatively more to the reduction in force-generating capacity of the knee extensors following submaximal intermittent isometric contractions in normoxia and mild to moderate hypoxia, whereas supraspinal fatigue plays a greater role in severe hypoxia.

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

2009 ◽  
Vol 21 (5) ◽  
pp. 1013-1022 ◽  
Author(s):  
Liana E. Brown ◽  
Elizabeth T. Wilson ◽  
Paul L. Gribble
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Motor Cortex ◽  
Motor Learning ◽  
Motor Skills ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Cortical Region ◽  
Robot Arm ◽  
Neural Representations

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 to reach in a novel force environment imposed by a robot arm performed better when later tested in the same environment than subjects who observed movements in a different environment. rTMS applied to M1 after observation reduced the beneficial effect of observing congruent forces, and eliminated the detrimental effect of observing incongruent forces. Stimulation of a control site in the frontal cortex had no effect on reaching. Our findings represent the first direct evidence that neural representations of motor skills in M1, a cortical region whose role has been firmly established for active motor learning, also underlie motor learning by observing.

scholarly journals Effects of Transcranial Direct Current Stimulation and High-Definition Transcranial Direct Current Stimulation Enhanced Motor Learning on Robotic Transcranial Magnetic Stimulation Motor Maps in Children

2021 ◽  
Vol 15 ◽  
Author(s):  
Adrianna Giuffre ◽  
Ephrem Zewdie ◽  
James G. Wrightson ◽  
Lauran Cole ◽  
Helen L. Carlson ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Motor Cortex ◽  
Motor Learning ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Magnetic Stimulation ◽  
High Definition ◽  
Left Hand ◽  
Direct Current Stimulation ◽  
Motor Maps

Introduction: Conventional transcranial direct current stimulation (tDCS) and high-definition tDCS (HD-tDCS) may improve motor learning in children. Mechanisms are not understood. Neuronavigated robotic transcranial magnetic stimulation (TMS) can produce individualised maps of primary motor cortex (M1) topography. We aimed to determine the effects of tDCS- and HD-tDCS-enhanced motor learning on motor maps.Methods: Typically developing children aged 12–18 years were randomised to right M1 anodal tDCS, HD-tDCS, or Sham during training of their left-hand on the Purdue Pegboard Task (PPT) over 5 days. Bilateral motor mapping was performed at baseline (pre), day 5 (post), and 6-weeks retention time (RT). Primary muscle was the first dorsal interosseous (FDI) with secondary muscles of abductor pollicis brevis (APB) and adductor digiti minimi (ADM). Primary mapping outcomes were volume (mm2/mV) and area (mm2). Secondary outcomes were centre of gravity (COG, mm) and hotspot magnitude (mV). Linear mixed-effects modelling was employed to investigate effects of time and stimulation type (tDCS, HD-tDCS, Sham) on motor map characteristics.Results: Twenty-four right-handed participants (median age 15.5 years, 52% female) completed the study with no serious adverse events or dropouts. Quality maps could not be obtained in two participants. No effect of time or group were observed on map area or volume. LFDI COG (mm) differed in the medial-lateral plane (x-axis) between tDCS and Sham (p = 0.038) from pre-to-post mapping sessions. Shifts in map COG were also observed for secondary left-hand muscles. Map metrics did not correlate with behavioural changes.Conclusion: Robotic TMS mapping can safely assess motor cortex neurophysiology in children undergoing motor learning and neuromodulation interventions. Large effects on map area and volume were not observed while changes in COG may occur. Larger controlled studies are required to understand the role of motor maps in interventional neuroplasticity in children.

scholarly journals Associatively-mediated suppression of corticospinal excitability: A transcranial magnetic stimulation (TMS) study

2019 ◽  
Author(s):  
Manuel S. Seet ◽  
Evan J. Livesey ◽  
Justin A. Harris
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Motor Cortex ◽  
Response Inhibition ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Motor Evoked Potentials ◽  
Human Subjects ◽  
Stop Signal ◽  
Corticospinal Excitability ◽  
Stop Signal Task

AbstractResponse inhibition—the suppression of prepotent behaviours when they are inappropriate— has been thought to rely on executive control. Against this received wisdom, it has been argued that external cues repeatedly associated with response inhibition can come to trigger response inhibition automatically without top-down command. The current project endeavoured to provide evidence for associatively-mediated motor inhibition. We tested the hypothesis that stop-associated stimuli can, in a bottom-up fashion, directly activate inhibitory mechanisms in the motor cortex. Human subjects were first trained on a stop-signal task. Once trained, the subjects received transcranial magnetic stimulation applied over their primary motor cortex during passive observation of either the stop signal (i.e. without any need to stop a response) or an equally familiar control stimulus never associated with stopping. Analysis of motor-evoked potentials showed that corticospinal excitability was reduced during exposure to the stop signal, which likely involved stimulus-driven activation of intracortical GABAergic interneurons. This result offers evidence for the argument that, through associative learning, stop-associated stimuli can engage local inhibitory processes at the level of the motor cortex.

scholarly journals Modulation of Effects of Intermittent Theta Burst Stimulation Applied Over Primary Motor Cortex (M1) by Conditioning Stimulation of the Opposite M1

2009 ◽  
Vol 102 (2) ◽  
pp. 766-773 ◽  
Author(s):  
Patrick Ragert ◽  
Mickael Camus ◽  
Yves Vandermeeren ◽  
Michael A. Dimyan ◽  
Leonardo G. Cohen
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Motor Cortex ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Corticospinal Excitability ◽  
Homeostatic Plasticity ◽  
Theta Burst Stimulation ◽  
Burst Stimulation ◽  
The Right ◽  
Theta Burst

The excitability of the human primary motor cortex (M1) as tested with transcranial magnetic stimulation (TMS) depends on its previous history of neural activity. Homeostatic plasticity might be one important physiological mechanism for the regulation of corticospinal excitability and synaptic plasticity. Although homeostatic plasticity has been demonstrated locally within M1, it is not known whether priming M1 could result in similar homeostatic effects in the homologous M1 of the opposite hemisphere. Here, we sought to determine whether down-regulating excitability (priming) in the right (R) M1 with 1-Hz repetitive transcranial magnetic stimulation (rTMS) changes the excitability-enhancing effect of intermittent theta burst stimulation (iTBS) applied over the homologous left (L) M1. Subjects were randomly allocated to one of four experimental groups in a sham-controlled parallel design with real or sham R M1 1-Hz TMS stimulation always preceding L M1 iTBS or sham by about 10 min. The primary outcome measure was corticospinal excitability in the L M1, as measured by recruitment curves (RCs). Secondary outcome measures included pinch force, simple reaction time, and tapping speed assessed in the right hand. The main finding of this study was that preconditioning R M1 with 1-Hz rTMS significantly decreased the excitability-enhancing effects of subsequent L M1 iTBS on RCs. Application of 1-Hz rTMS over R M1 alone and iTBS over L M1 alone resulted in increased RC in L M1 relative to sham interventions. The present findings are consistent with the hypothesis that homeostatic mechanisms operating across hemispheric boundaries contribute to regulate motor cortical function in the primary motor cortex.

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