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

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.

scholarly journals Spatially and temporally distinct encoding of muscle and kinematic information in rostral and caudal primary motor cortex

2019 ◽  
Author(s):  
James Kolasinski ◽  
Diana C. Dima ◽  
David M. A. Mehler ◽  
Alice Stephenson ◽  
Sara Valadan ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Muscle Activity ◽  
Primary Motor Cortex ◽  
Temporal Analysis ◽  
Hand Movements ◽  
Imaging Data ◽  
Top Down ◽  
Bottom Up ◽  
Data Glove ◽  
Kinematic Information

AbstractHand movements are controlled by neuronal networks in primary motor cortex (M1). The organising principle in M1 does not follow an anatomical body map, but rather a distributed representational structure in which motor primitives are combined to produce motor outputs. Both 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? Moreover, to what extent is information related to muscle activity encoded in motor cortex? 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 fMRI and MEG, a spatial and temporal multivariate representational similarity analysis revealed encoding of kinematic information from data glove recordings in more caudal regions of M1, over 200ms before movement onset. In contrast, patterns of muscle activity from EMG were encoded in more rostral motor regions later in the cycle of movement. Our spatial and temporal analysis provide compelling evidence that top-down control of dexterous movement engages kinematic representations in caudal regions of M1 prior to movement production; an area with direct cortico-motorneuronal connections. Muscle information encoded more rostrally in M1 was engaged later, suggestive of involvement in bottom-up signalling.

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.

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

2018 ◽  
Vol 29 (7) ◽  
pp. 2924-2931 ◽  
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.

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

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.

Modulation of Associative Human Motor Cortical Plasticity by Attention

2004 ◽  
Vol 92 (1) ◽  
pp. 66-72 ◽  
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.

Intracortical Inhibition and Facilitation in Different Representations of the Human Motor Cortex

1998 ◽  
Vol 80 (6) ◽  
pp. 2870-2881 ◽  
Author(s):  
Robert Chen ◽  
Alda Tam ◽  
Cathrin Bütefisch ◽  
Brian Corwell ◽  
Ulf Ziemann ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Biceps Brachii ◽  
Conditioning Stimulus ◽  
Motor Evoked Potential ◽  
Intracortical Inhibition ◽  
Abductor Hallucis ◽  
Human Motor Cortex ◽  
Human Motor ◽  
Motor Representations ◽  
Intracortical Inhibition And Facilitation

Chen, Robert, Alda Tam, Cathrin Bütefisch, Brian Corwell, Ulf Ziemann, John C. Rothwell, and Leonardo G. Cohen. Intracortical inhibition and facilitation in different representations of the human motor cortex. J. Neurophysiol. 80: 2870–2881, 1998. Intracortical inhibition (ICI) and intracortical facilitation (ICF) of the human motor cortex can be studied with paired transcranial magnetic stimulation (TMS). Plastic changes and some neurological disorders in humans are associated with changes in ICI and ICF. Although well characterized in the hand representation, it is not known if ICI and ICF vary across different body part representations. Therefore we studied ICI and ICF in different motor representations of the human motor cortex. The target muscles were rectus abdominus (RA), biceps brachii (BB), abductor pollicis brevis (APB), quadriceps femoris (QF), and abductor hallucis (AH). For each muscle, we measured the rest and active motor thresholds (MTs), the motor-evoked potential (MEP) stimulus-response curve (MEP recruitment), ICI, and ICF. The effects of different interstimulus intervals (ISIs) were studied with a conditioning stimulus (CS) intensity of 80% active MT. The effects of different CS intensities were studied at ISI of 2 ms for ICI and ISI of 15 ms for ICF. MT was lowest for APB, followed by BB, AH, and QF, and was highest for RA. Except for BB, MEP recruitment was generally steeper for muscles with lower MT. ICI and ICF were present in all the motor representations tested. The stimulus intensity necessary to elicit ICI was consistently lower than that required to elicit ICF, suggesting that they are mediated by separate mechanisms. Despite wide differences in MT and MEP recruitment, the absolute CS intensities (expressed as percentage of the stimulator's output) required to elicit ICI and ICF appear unrelated to MT and MEP recruitment in the different muscles tested. These findings suggest that the intracortical mechanisms for inhibition and facilitation in different motor representations are not related to the strength of corticospinal projections.

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

2020 ◽  
Author(s):  
Francesca Vitale ◽  
Iván Padrón ◽  
Alessio Avenanti ◽  
Manuel de Vega
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Motor Evoked Potentials ◽  
Brain Activity ◽  
Linguistic Meaning ◽  
Human Motor Cortex ◽  
Specific Memory ◽  
Action Language ◽  
Motor Excitability ◽  
Human Motor

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.

Operculo-insular and anterior cingulate plasticity induced by transcranial magnetic stimulation in the human motor cortex: a dynamic casual modeling study

2021 ◽  
Vol 125 (4) ◽  
pp. 1180-1190
Author(s):  
Duncan J. Hodkinson ◽  
Andreas Bungert ◽  
Richard Bowtell ◽  
Stephen R. Jackson ◽  
JeYoung Jung
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Motor Cortex ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Effective Connectivity ◽  
Anterior Cingulate ◽  
Human Motor Cortex ◽  
Promising Treatment ◽  
Human Motor ◽  
Lateral Pain

Transcranial magnetic stimulation of the primary motor cortex (M1) is a promising treatment for chronic pain, but its mechanism of action remains unclear. Competing dynamic causal models of effective connectivity between M1 and medial and lateral pain systems suggest direct input into the insular, anterior cingulate cortex, and parietal operculum. This supports the hypothesis that analgesia produced from M1 stimulation most likely acts through the activation of top-down processes associated with intracortical modulation.

Handedness and Asymmetry of Hand Representation in Human Motor Cortex

1998 ◽  
Vol 79 (4) ◽  
pp. 2149-2154 ◽  
Author(s):  
J. Volkmann ◽  
A. Schnitzler ◽  
O. W. Witte ◽  
H.-J. Freund
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Right Hemisphere ◽  
Current Source ◽  
Dominant Hemisphere ◽  
Human Motor Cortex ◽  
Human Motor ◽  
Left And Right ◽  
Hand Area ◽  
Dipole Sources

Volkmann, J., A. Schnitzler, O. W. Witte, and H.-J. Freund. Handedness and asymmetry of hand representation in human motor cortex. J. Neurophysiol. 79: 2149–2154, 1998. The cortical representation of five simple hand and finger movements in the human motor cortex was determined in left- and right-handed people with whole-head magnetoencephalography. Different movements were found to be represented by spatially segregated dipolar sources in primary motor cortex. The spatial arrangement of neuronal sources for digit and wrist movements was nonsomatotopic and varied greatly between subjects. As an estimator of hand area size in primary motor cortex, we determined the smallest cuboid volume enclosing the five dipole sources within the left and right hemisphere of each subject. Interhemispheric comparison revealed a significant increase of this volume in primary motor cortex opposite to the preferred hand. This asymmetry was due to a greater spatial segregation of neuronal dipole generators subserving different hand and finger actions in the dominant hemisphere. Mean Euclidean distances between dipole sources for different movements were 10.7 ± 3.5 mm in the dominant and 9.4 ± 3.5 mm in the nondominant hemisphere (mean ± SD; P = 0.01, two-tailed t-test). The expansion of hand representation in primary motor cortex could not simply be attributed to a greater number of pyramidal cells devoted to each particular movement as inferred from current source amplitudes. The degree of hemispheric asymmetry of hand area size in the primary motor cortex was correlated highly with the asymmetry of hand performance in a standardized handedness test ( r = −0.76, P < 0.01). These results demonstrate for the first time a biological correlate of handedness in human motor cortex. The expansion of hand motor cortex in the dominant hemisphere may provide extra space for the cortical encoding of a greater motor skill repertoire of the preferred hand.

scholarly journals Somatosensory responses in a human motor cortex

2013 ◽  
Vol 109 (8) ◽  
pp. 2192-2204 ◽  
Author(s):  
Ammar Shaikhouni ◽  
John P. Donoghue ◽  
Leigh R. Hochberg
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Activity Patterns ◽  
Human Motor Cortex ◽  
Sensory Pathways ◽  
Fundamental Properties ◽  
Computer Interfaces ◽  
Somatosensory Responses ◽  
Human Motor ◽  
Contralateral Shoulder

Somatic sensory signals provide a major source of feedback to motor cortex. Changes in somatosensory systems after stroke or injury could profoundly influence brain computer interfaces (BCI) being developed to create new output signals from motor cortex activity patterns. We had the unique opportunity to study the responses of hand/arm area neurons in primary motor cortex to passive joint manipulation in a person with a long-standing brain stem stroke but intact sensory pathways. Neurons responded to passive manipulation of the contralateral shoulder, elbow, or wrist as predicted from prior studies of intact primates. Thus fundamental properties and organization were preserved despite arm/hand paralysis and damage to cortical outputs. The same neurons were engaged by attempted arm actions. These results indicate that intact sensory pathways retain the potential to influence primary motor cortex firing rates years after cortical outputs are interrupted and may contribute to online decoding of motor intentions for BCI applications.

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