Enhancing Motor Brain Activity Improves Memory for Action Language: A tDCS Study

Abstract The embodied cognition approach to linguistic meaning posits that action language understanding is grounded in sensory–motor systems. However, evidence that the human motor cortex is necessary for action language memory is meager. To address this issue, in two groups of healthy individuals, we perturbed the left primary motor cortex (M1) by means of either anodal or cathodal transcranial direct current stimulation (tDCS), before participants had to memorize lists of manual action and attentional sentences. In each group, participants received sham and active tDCS in two separate sessions. Following anodal tDCS (a-tDCS), participants improved the recall of action sentences compared with sham tDCS. No similar effects were detected following cathodal tDCS (c-tDCS). Both a-tDCS and c-tDCS induced variable changes in motor excitability, as measured by motor-evoked potentials induced by transcranial magnetic stimulation. Remarkably, across groups, action-specific memory improvements were positively predicted by changes in motor excitability. We provide evidence that excitatory modulation of the motor cortex selectively improves performance in a task requiring comprehension and memory of action sentences. These findings indicate that M1 is necessary for accurate processing of linguistic meanings and thus provide causal evidence that high-order cognitive functions are grounded in the human motor system.

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

Frontiers in Neuroscience ◽

10.3389/fnins.2021.800436 ◽

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.

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Mechanisms underlying long-interval cortical inhibition in the human motor cortex: a TMS-EEG study

Journal of Neurophysiology ◽

10.1152/jn.00762.2012 ◽

2013 ◽

Vol 109 (1) ◽

pp. 89-98 ◽

Cited By ~ 65

Author(s):

Nigel C. Rogasch ◽

Zafiris J. Daskalakis ◽

Paul B. Fitzgerald

Keyword(s):

Motor Cortex ◽

Motor Evoked Potentials ◽

Cortical Inhibition ◽

Human Motor Cortex ◽

Paired Pulse ◽

Small Hand ◽

Human Motor ◽

Hand Muscle ◽

Underlying Mechanisms ◽

Eeg Conditioning

Long-interval cortical inhibition (LICI) refers to suppression of neuronal activity following paired-pulse transcranial magnetic stimulation (TMS) with interstimulus intervals (ISIs) between 50 and 200 ms. LICI can be measured either from motor-evoked potentials (MEPs) in small hand muscles or directly from the cortex using concurrent electroencephalography (EEG). However, it remains unclear whether EEG inhibition reflects similar mechanisms to MEP inhibition. Eight healthy participants received single- and paired-pulse TMS (ISI = 100 ms) over the motor cortex. MEPs were measured from a small hand muscle (first dorsal interosseus), whereas early (P30, P60) and late (N100) TMS-evoked cortical potentials (TEPs) were measured over the motor cortex using EEG. Conditioning and test TMS intensities were altered, and modulation of LICI strength was measured using both methods. LICI of MEPs and both P30 and P60 TEPs increased in strength with increasing conditioning intensities and decreased with increasing test intensities. LICI of N100 TEPs remained unchanged across all conditions. In addition, MEP and P30 LICI strength correlated with the slope of the N100 evoked by the conditioning pulse. LICI of early and late TEP components was differentially modulated with altered TMS intensities, suggesting independent underlying mechanisms. LICI of P30 is consistent with inhibition of cortical excitation similar to MEPs, whereas LICI of N100 may reflect presynaptic autoinhibition of inhibitory interneurons. The N100 evoked by the conditioning pulse is consistent with the mechanism responsible for LICI, most likely GABAB-mediated inhibition of cortical activity.

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NMDA Receptor-Mediated Motor Cortex Plasticity After 20 Hz Transcranial Alternating Current Stimulation

Cerebral Cortex ◽

10.1093/cercor/bhy160 ◽

2018 ◽

Vol 29 (7) ◽

pp. 2924-2931 ◽

Cited By ~ 26

Author(s):

M Wischnewski ◽

M Engelhardt ◽

M A Salehinejad ◽

D J L G Schutter ◽

M -F Kuo ◽

...

Keyword(s):

Motor Cortex ◽

Primary Motor Cortex ◽

Cortical Excitability ◽

Alternating Current ◽

Beta Oscillations ◽

Human Motor Cortex ◽

After Effects ◽

Transcranial Alternating Current Stimulation ◽

Human Motor ◽

Motor Cortex Plasticity

Abstract Transcranial alternating current stimulation (tACS) has been shown to modulate neural oscillations and excitability levels in the primary motor cortex (M1). These effects can last for more than an hour and an involvement of N-methyl-d-aspartate receptor (NMDAR) mediated synaptic plasticity has been suggested. However, to date the cortical mechanisms underlying tACS after-effects have not been explored. Here, we applied 20 Hz beta tACS to M1 while participants received either the NMDAR antagonist dextromethorphan or a placebo and the effects on cortical beta oscillations and excitability were explored. When a placebo medication was administered, beta tACS was found to increase cortical excitability and beta oscillations for at least 60 min, whereas when dextromethorphan was administered, these effects were completely abolished. These results provide the first direct evidence that tACS can induce NMDAR-mediated plasticity in the motor cortex, which contributes to our understanding of tACS-induced influences on human motor cortex physiology.

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

10.1101/2021.03.26.437107 ◽

2021 ◽

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

Temporal interference (TI) stimulation is a new technique of noninvasive 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 elucidate. In this study, this issue is investigated in the human primary motor cortex. Participants attended three sessions of 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. The results indicate that TI stimulation with different envelope frequencies influenced different motor functions. In the RRTT experiment, only 70 Hz TI stimulation had a promoting effect on the reaction time 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. 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.

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Associative plasticity in the human motor cortex is enhanced by concurrently targeting separate muscle representations with excitatory and inhibitory protocols

Journal of Neurophysiology ◽

10.1152/jn.00794.2015 ◽

2016 ◽

Vol 115 (4) ◽

pp. 2191-2198 ◽

Cited By ~ 2

Author(s):

Marc R. Kamke ◽

Abbey S. Nydam ◽

Martin V. Sale ◽

Jason B. Mattingley

Keyword(s):

Motor Cortex ◽

Primary Motor Cortex ◽

Control Experiment ◽

Motor Evoked Potentials ◽

Spillover Effects ◽

Abductor Pollicis Brevis ◽

Human Motor Cortex ◽

Before And After ◽

Abductor Digiti Minimi ◽

Intrinsic Hand Muscle

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.

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Modulation of Associative Human Motor Cortical Plasticity by Attention

Journal of Neurophysiology ◽

10.1152/jn.00383.2003 ◽

2004 ◽

Vol 92 (1) ◽

pp. 66-72 ◽

Cited By ~ 307

Author(s):

Katja Stefan ◽

Matthias Wycislo ◽

Joseph Classen

Keyword(s):

Motor Cortex ◽

Primary Motor Cortex ◽

Cognitive Task ◽

Silent Period ◽

Abductor Pollicis Brevis ◽

Human Motor Cortex ◽

Target Hand ◽

Human Motor ◽

The Subject ◽

The Right

The role of attention in generating motor memories remains controversial principally because it is difficult to separate the effects of attention from changes in kinematics of motor performance. We attempted to disentangle attention from performance effects by varying attention while plasticity was induced in human primary motor cortex by external stimulation in the absence of voluntary movement. A paired associative stimulation (PAS) protocol was employed consisting of repetitive application of single afferent electric stimuli, delivered to the right median nerve, paired with single-pulse transcranial magnetic stimulation (TMS) over the optimal site for activation of the right abductor pollicis brevis muscle (APB) to generate near-synchronous events in the left primary motor cortex. In experiment 1, the spatial location of attention was varied. PAS failed to induce plasticity when the subject's attention was directed to their left hand, away from the right target hand the cortical representation of which was being stimulated by PAS. In experiment 2, the grade of attention to the target hand was manipulated. PAS-induced plasticity was maximal when the subject viewed their target hand, and its magnitude was slightly reduced when the subject could only feel their hand. Conversely, plasticity was completely blocked when the subject's attention was diverted from the target hand by a competing cognitive task. A similar modulation by attention was observed for PAS-induced changes in the duration of the silent period evoked by TMS in voluntarily contracted muscle. Associative plasticity in the human motor cortex depends decisively on attention.

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Facilitation of motor excitability during listening to spoken sentences is not modulated by noise or semantic coherence

10.1101/168864 ◽

2017 ◽

Cited By ~ 1

Author(s):

Muriel T.N. Panouillères ◽

Rowan Boyles ◽

Jennifer Chesters ◽

Kate E. Watkins ◽

Riikka Möttönen

Keyword(s):

Motor Cortex ◽

Speech Processing ◽

Motor System ◽

Primary Motor Cortex ◽

Motor Evoked Potentials ◽

Signal To Noise Ratio ◽

Semantic Context ◽

Noisy Environment ◽

Semantic Coherence ◽

Motor Excitability

AbstractComprehending speech can be particularly challenging in a noisy environment and in the absence of semantic context. It has been proposed that the articulatory motor system would be recruited especially in difficult listening conditions. However, it remains unknown how signal-to-noise ratio (SNR) and semantic context affect the recruitment of the articulatory motor system when listening to continuous speech. The aim of the present study was to address the hypothesis that involvement of the articulatory motor cortex increases when the intelligibility and clarity of the spoken sentences decreases, because of noise and the lack of semantic context. We applied Transcranial Magnetic Stimulation (TMS) to the lip and hand representations in the primary motor cortex and measured motor evoked potentials from the lip and hand muscles, respectively, to evaluate motor excitability when young adults listened to sentences. In Experiment 1, we found that the excitability of the lip motor cortex was facilitated during listening to both semantically anomalous and coherent sentences in noise, but neither SNR nor semantic context modulated the facilitation. In Experiment 2, we replicated these findings and found no difference in the excitability of the lip motor cortex between sentences in noise and clear sentences without noise. Thus, our results show that the articulatory motor cortex is involved in speech processing even in optimal and ecologically valid listening conditions and that its involvement is not modulated by the intelligibility and clarity of speech.

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Spatially and Temporally Distinct Encoding of Muscle and Kinematic Information in Rostral and Caudal Primary Motor Cortex

Cerebral Cortex Communications ◽

10.1093/texcom/tgaa009 ◽

2020 ◽

Vol 1 (1) ◽

Author(s):

James Kolasinski ◽

Diana C Dima ◽

David M A Mehler ◽

Alice Stephenson ◽

Sara Valadan ◽

...

Keyword(s):

Motor Cortex ◽

Primary Motor Cortex ◽

Imaging Data ◽

Top Down ◽

Human Motor Cortex ◽

Electrophysiological Recordings ◽

Human Motor ◽

Sensory Responses ◽

Motor Representations ◽

Kinematic Information

Abstract The organizing principle of human motor cortex does not follow an anatomical body map, but rather a distributed representational structure in which motor primitives are combined to produce motor outputs. Electrophysiological recordings in primates and human imaging data suggest that M1 encodes kinematic features of movements, such as joint position and velocity. However, M1 exhibits well-documented sensory responses to cutaneous and proprioceptive stimuli, raising questions regarding the origins of kinematic motor representations: are they relevant in top-down motor control, or are they an epiphenomenon of bottom-up sensory feedback during movement? Here we provide evidence for spatially and temporally distinct encoding of kinematic and muscle information in human M1 during the production of a wide variety of naturalistic hand movements. Using a powerful combination of high-field functional magnetic resonance imaging and magnetoencephalography, a spatial and temporal multivariate representational similarity analysis revealed encoding of kinematic information in more caudal regions of M1, over 200 ms before movement onset. In contrast, patterns of muscle activity were encoded in more rostral motor regions much later after movements began. We provide compelling evidence that top-down control of dexterous movement engages kinematic representations in caudal regions of M1 prior to movement production.

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Short- and long-latency interhemispheric inhibitions are additive in human motor cortex

Journal of Neurophysiology ◽

10.1152/jn.00960.2012 ◽

2013 ◽

Vol 109 (12) ◽

pp. 2955-2962 ◽

Cited By ~ 4

Author(s):

Soumya Ghosh ◽

Arpan R. Mehta ◽

Guan Huang ◽

Carolyn Gunraj ◽

Tasnuva Hoque ◽

...

Keyword(s):

Motor Cortex ◽

Primary Motor Cortex ◽

Neural Circuits ◽

Motor Evoked Potentials ◽

Conditioning Stimulus ◽

Interhemispheric Inhibition ◽

Human Motor Cortex ◽

Inhibitory Processes ◽

Long Latency ◽

The Right

Transcranial magnetic stimulation (TMS) of the human primary motor cortex (M1) at suprathreshold strength results in inhibition of M1 in the opposite hemisphere, a process termed interhemispheric inhibition (IHI). Two phases of IHI, termed short-latency interhemispheric inhibition (SIHI) and long-latency interhemispheric inhibition (LIHI), involving separate neural circuits, have been identified. In this study we evaluated how these two inhibitory processes interact with each other. We studied 10 healthy right-handed subjects. A test stimulus (TS) was delivered to the left M1, and motor evoked potentials (MEPs) were recorded from the right first dorsal interosseous (FDI) muscle. Contralateral conditioning stimuli (CCS) were applied to the right M1 either 10 ms or 50 ms prior to the TS, inducing SIHI and LIHI, respectively, in the left M1. The effects of SIHI and LIHI alone, and SIHI and LIHI delivered together, were compared. The TS was adjusted to produce 1-mV or 0.5-mV MEPs when applied alone or after CCS. SIHI and LIHI were found to be additive when delivered together, irrespective of the strength of the TS. The interactions were affected neither by varying the strength of the conditioning stimulus producing SIHI nor by altering the current direction of the TS. Small or opposing interactions, however, may not have been detected. These results support previous findings suggesting that SIHI and LIHI act through different neural circuits. Such inhibitory processes may be used individually or additively during motor tasks and should be studied as separate processes in functional studies.

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Transcranial Magnetic Stimulation Study of Plastic Changes of Human Motor Cortex after Repetitive Simple Muscle Contractions

Perceptual and Motor Skills ◽

10.2466/pms.2002.95.3.699 ◽

2002 ◽

Vol 95 (3) ◽

pp. 699-705 ◽

Cited By ~ 16

Author(s):

Shikako Hayashi ◽

Yoshiteru Hasegawa ◽

Tatsuya Kasai

Keyword(s):

Transcranial Magnetic Stimulation ◽

Motor Cortex ◽

Magnetic Stimulation ◽

Structural Changes ◽

Primary Motor Cortex ◽

Motor Evoked Potentials ◽

Human Subjects ◽

Motor Evoked Potential ◽

Neural Activation ◽

Human Motor Cortex

Studies of use-dependent changes in neural activation have recently focused on the primary motor cortex. To detect the excitability changes in the primary motor cortex after practice in human subjects, motor-evoked potentials by transcranial magnetic stimulation during motor imagery after just 10 sessions of simple index finger abduction were examined. The present results indicate that width of the output map and amplitudes of motor-evoked potential became progressively larger until practice ended. These flexible short-term modulations of human primary motor cortex seem important and could lead to structural changes in the intracortical networks as the skill becomes more learned and automatic, i.e., ‘adaptation’ as one of the neural mechanisms related to motor learning.

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