Rapid crossed responses in an intrinsic hand muscle during perturbed bimanual movements

Mechanical perturbations in one upper limb often elicit corrective responses in both the perturbed as well as its contralateral and unperturbed counterpart. These crossed corrective responses have been shown to be sensitive to the bimanual requirements of the perturbation, but crossed responses (CRs) in hand muscles are far less well studied. Here, we investigate corrective CRs in an intrinsic hand muscle, the first dorsal interosseous (1DI), to clockwise and anticlockwise mechanical perturbations to the contralateral index finger while participants performed a bimanual finger abduction task. We found that the CRs in the unperturbed 1DI were sensitive to the direction of the perturbation of the contralateral index finger. However, the size of the CRs was not sensitive to the amplitude of the contralateral perturbation nor its context within the bimanual task. The onset latency of the CRs was too fast to be purely transcortical (<70 ms) in 12/12 participants. This confirms that during isolated bimanual finger movements, sensory feedback from one hand can influence the other, but the pathways mediating the earliest components of this interaction are likely to involve subcortical systems such as the brainstem or spinal cord, which may afford less flexibility to the task demands. NEW & NOTEWORTHY An intrinsic hand muscle shows a crossed response to a perturbation of the contralateral index finger. The crossed response is dependent on the direction of the contralateral perturbation but not on the amplitude or the bimanual requirements of the movement, suggesting a far less flexible control policy than those governing crossed responses in more proximal muscles. The crossed response is too fast to be purely mediated by transcortical pathways, suggesting subcortical contributions.

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IMPACT OF FINGERTIP ACTIONS ON TOTAL POWER OF SURFACE ELECTROMYOGRAPHY FROM EXTRINSIC HAND MUSCLES

Journal of Mechanics in Medicine and Biology ◽

10.1142/s0219519411004800 ◽

2012 ◽

Vol 12 (03) ◽

pp. 1250056

Author(s):

D. D. YANG ◽

W. S. HOU ◽

X. Y. WU ◽

J. ZHENG ◽

X. L. ZHENG ◽

...

Keyword(s):

Surface Electromyography ◽

Index Finger ◽

Statistical Significance ◽

Middle Finger ◽

Total Power ◽

Force Level ◽

Hand Muscles ◽

Fingertip Force ◽

Hand Muscle ◽

The Relationship

Quantizing the relationship between finger force and multitendoned extrinsic hand muscles could be useful for understanding the control strategies that underlie the coordination of finger movements and forces. The objective of this study is to explore the relationship of fingertip force production and total power of surface electromyography (sEMG) recorded on extrinsic hand muscles under isometric voluntary contraction. Thirteen healthy volunteers were recruited to participate in this study. In the designed force-tracking tasks, all volunteers were required to produce a certain force with either index finger or middle finger to match the target force for 5 s. Meanwhile, the sEMG signals were acquired from two extrinsic hand muscles: extensor digitorum (ED) and flexor digitorum superficialis (FDS). For each trial, sEMG of the effective force segment was extracted; then, the power spectrum was estimated based on autoregressive (AR) model and from which the corresponding total power of sEMG was computed. The experimental results reveal that the total power of sEMG linearly increases with force level regardless of the task finger and extrinsic hand muscle. It is also found that the total power obtained from index finger is significantly less than that of middle finger for FDS at the same force level (p < 0.05), while this kind of statistical significance cannot be found for ED. However, with respect to the measurement of total power, the type of extrinsic hand muscle has not exhibited significantly different contribution to the task finger under a certain fingertip force level. The findings of this study indicate that the total power of the extrinsic hand muscle's sEMG can be used to characterize finger's activities.

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Direct and Indirect Corticospinal Control of Arm and Hand Motoneurons in the Squirrel Monkey (Saimiri sciureus)

Journal of Neurophysiology ◽

10.1152/jn.1997.78.2.721 ◽

1997 ◽

Vol 78 (2) ◽

pp. 721-733 ◽

Cited By ~ 48

Author(s):

M. A. Maier ◽

E. Olivier ◽

S. N. Baker ◽

P. A. Kirkwood ◽

T. Morris ◽

...

Keyword(s):

Squirrel Monkey ◽

Macaque Monkey ◽

Saimiri Sciureus ◽

Excitatory Postsynaptic Potential ◽

Onset Latency ◽

Implanted Electrodes ◽

Postsynaptic Potential ◽

Common Response ◽

Hand Muscle ◽

Comparable Sample

Maier, M. A., E. Olivier, S. N. Baker, P. A. Kirkwood, T. Morris, and R. N. Lemon. Direct and indirect corticospinal control of arm and hand motoneurons in the squirrel monkey ( Saimiri sciureus). J. Neurophysiol. 78: 721–733, 1997. Anatomic evidence suggests that direct corticomotoneuronal (CM) projections to hand motoneurons in the New World squirrel monkey ( Saimiri sciureus) are weak or absent, but electrophysiological evidence is lacking. The nature of the corticospinal linkage to these motoneurons was therefore investigated first with the use of transcranial magnetic stimulation (TMS) of the motor cortex under ketamine sedation in five monkeys. TMS produced early responses in hand muscle electromyogram, but thresholds were high (compared with macaque monkey) and the onset latency was variable. Second, stimulation of the pyramidal tract (PT) was carried out with the use of chronically implanted electrodes in ketamine-sedated monkeys; this produced more robust responses that were markedly facilitated by repetitive stimulation, with little decrease in latency on the third compared with the first shock. Finally, postsynaptic potentials were recorded intracellularly from 93 arm and hand motoneurons in five monkeys under general chloralose anesthesia. After a single PT stimulus, the most common response was a small, slowly rising excitatory postsynaptic potential (EPSP), either alone (35 of 93 motoneurons) or followed by an inhibitory postsynaptic potential (39 of 93). The segmental delay of the early EPSPs was within the monosynaptic range (mean 0.85 ms); however, the rise time of these EPSPs was slow (mean 1.3 ms) and their amplitude was small (mean 0.74 mV). These values are significantly slower and smaller than EPSPs in a comparable sample of Old World macaque monkey motoneurons. The results show that CM connections do exist in the squirrel monkey but that they are weak and possibly located on the remote dendrites of the motoneurons. The findings are consistent with earlier anatomic studies. Repetitive PT stimulation produced large, late EPSPs in some motoneurons, suggesting that, in this species, there are relatively strong nonmonosynaptic pathways linking the corticospinal tract to hand motoneurons.

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Evidence that low-threshold muscle afferents evoke long-latency stretch reflexes in human hand muscles

Journal of Neurophysiology ◽

10.1152/jn.1991.65.5.1089 ◽

1991 ◽

Vol 65 (5) ◽

pp. 1089-1097 ◽

Cited By ~ 19

Author(s):

J. Noth ◽

M. Schwarz ◽

K. Podoll ◽

F. Motamedi

Keyword(s):

Index Finger ◽

Angular Displacement ◽

Metacarpophalangeal Joint ◽

Muscle Afferents ◽

Human Hand ◽

Hand Muscles ◽

Long Latency ◽

M2 Response ◽

Spinal Afferents ◽

Wrist Flexors

1. The aim of the present study was to identify the type of spinal afferents involved in the generation of the long-latency response in intrinsic human hand muscles. Position-controlled extensions were imposed on the index finger or on the wrist of healthy subjects who were exerting a steady voluntary flexion force at the relevant joint. Averaged surface electromyographic (EMG) responses of the first dorsal interosseus muscle (FDI) or of the wrist flexors were evaluated with respect to latency and size. 2. Small transient angular displacements of the index finger (1 degree, as measured at the metacarpophalangeal joint), which are supposed to excite primary rather than secondary afferents, evoked two clearly discernible EMG responses with mean latencies of 32.3 ms (M1 response) and 54.7 ms (M2 response), respectively. The size of the M2 response exceeded the size of the M1 response by 60%. In the wrist flexors, transient stretch (1 degree) gave rise to a large M1 response (latency 22.8 ms) and a small, inconstent M2 response. 3. Small-amplitude vibration of the index finger elicited EMG responses in the FDI that were qualitatively and quantitatively similar to those seen in response to small transient stretches of the index finger. This was also true for fast ramp-and-hold stretches (stretch velocity 400 degrees/s, amplitude 5 degrees), whereas slow ramp-and-hold stretches (125 degrees/s, 5 degrees) elicited predominantly M2 responses. 4. In the FDI, the mechanical threshold of the M1 and M2 response to the transient angular displacement was approximately 0.15 degrees, with a tendency for the M2 response to appear at a lower threshold.(ABSTRACT TRUNCATED AT 250 WORDS)

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Time-dependent modulation of spinal excitability during action observation in the macaque monkey

10.1101/768804 ◽

2019 ◽

Author(s):

S.J. Jerjian ◽

R.N. Lemon ◽

A. Kraskov

Keyword(s):

Pyramidal Tract ◽

Rhesus Macaques ◽

Action Observation ◽

Macaque Monkey ◽

Reach To Grasp ◽

Hand Muscles ◽

Spinal Circuitry ◽

Hand Muscle ◽

Spinal Excitability ◽

Muscle Responses

ABSTRACTNeurons in the primate motor cortex, including identified pyramidal tract neurons projecting to the spinal cord, respond to the observation of others’ actions, yet this does not cause movement in the observer. Here, we investigated changes in spinal excitability during action observation by monitoring short latency electromyographic responses produced by single shocks delivered directly to the pyramidal tract. Responses in hand and digit muscles were recorded from two adult rhesus macaques while they performed, observed or withheld reach-to-grasp and hold actions. We found modest grasp-specific facilitation of hand muscle responses during hand shaping for grasp, which persisted when the grasp was predictable but obscured from the monkey’s vision. We also found evidence of a more general inhibition before observed movement onset, and the size of this inhibition effect was comparable to the inhibition after an explicit NoGo signal. These results confirm that the spinal circuitry controlling hand muscles is modulated during action observation, and this may be driven by internal representations of actions. The relatively modest changes in spinal excitability during observation suggest net corticospinal outflow exerts only minor, sub-threshold changes on hand motoneuron pools, thereby preventing any overflow of mirror activity into overt movement.

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Cross-Modal Audiovisual Modulation of Corticospinal Motor Synergies in Professional Piano Players: A TMS Study during Motor Imagery

Neural Plasticity ◽

10.1155/2019/1328453 ◽

2019 ◽

Vol 2019 ◽

pp. 1-11

Author(s):

Simone Rossi ◽

Danilo Spada ◽

Marco Emanuele ◽

Monica Ulivelli ◽

Emiliano Santarnecchi ◽

...

Keyword(s):

Motor Imagery ◽

Index Finger ◽

Task Demands ◽

Muscle Synergies ◽

Imagery Task ◽

Musical Performances ◽

Motor Synergies ◽

Specific Muscle ◽

Motor Synergy ◽

The Right

Transcranial magnetic stimulation was used to investigate corticospinal output changes in 10 professional piano players during motor imagery of triad chords in C major to be “mentally” performed with three fingers of the right hand (thumb, index, and little finger). Five triads were employed in the task; each composed by a stable 3rd interval (C4-E4) and a varying third note that could generate a 5th (G4), a 6th (A4), a 7th (B4), a 9th (D5), or a 10th (E5) interval. The 10th interval chord was thought to be impossible in actual execution for biomechanical reasons, as long as the thumb and the index finger remained fixed on the 3rd interval. Chords could be listened from loudspeakers, read on a staff, or listened and read at the same time while performing the imagery task. The corticospinal output progressively increased along with task demands in terms of mental representation of hand extension. The effects of audio, visual, or audiovisual musical stimuli were generally similar, unless motor imagery of kinetically impossible triads was required. A specific three-effector motor synergy was detected, governing the representation of the progressive mental extension of the hand. Results demonstrate that corticospinal facilitation in professional piano players can be modulated according to the motor plan, even if simply “dispatched” without actual execution. Moreover, specific muscle synergies, usually encoded in the motor cortex, emerge along the cross-modal elaboration of musical stimuli and in motor imagery of musical performances.

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Re-emergence of hand-muscle representations in human motor cortex after hand allograft

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.0809614106 ◽

2009 ◽

Vol 106 (17) ◽

pp. 7197-7202 ◽

Cited By ~ 38

Author(s):

Claudia D. Vargas ◽

Antoine Aballéa ◽

Érika C. Rodrigues ◽

Karen T. Reilly ◽

Catherine Mercier ◽

...

Keyword(s):

Transcranial Magnetic Stimulation ◽

Motor Cortex ◽

Upper Limb ◽

Magnetic Stimulation ◽

Cortical Representation ◽

Human Motor Cortex ◽

Hand Muscles ◽

Right Hand ◽

Hand Muscle ◽

The Right

The human primary motor cortex (M1) undergoes considerable reorganization in response to traumatic upper limb amputation. The representations of the preserved arm muscles expand, invading portions of M1 previously dedicated to the hand, suggesting that former hand neurons are reassigned to the control of remaining proximal upper limb muscles. Hand allograft offers a unique opportunity to study the reversibility of such long-term cortical changes. We used transcranial magnetic stimulation in patient LB, who underwent bilateral hand transplantation 3 years after a traumatic amputation, to longitudinally track both the emergence of intrinsic (from the donor) hand muscles in M1 as well as changes in the representation of stump (upper arm and forearm) muscles. The same muscles were also mapped in patient CD, the first bilateral hand allograft recipient. Newly transplanted intrinsic muscles acquired a cortical representation in LB's M1 at 10 months postgraft for the left hand and at 26 months for the right hand. The appearance of a cortical representation of transplanted hand muscles in M1 coincided with the shrinkage of stump muscle representations for the left but not for the right side. In patient CD, transcranial magnetic stimulation performed at 51 months postgraft revealed a complete set of intrinsic hand-muscle representations for the left but not the right hand. Our findings show that newly transplanted muscles can be recognized and integrated into the patient's motor cortex.

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CHARACTERIZATION OF FINGER ISOMETRIC FORCE PRODUCTION WITH MAXIMUM POWER OF SURFACE ELECTROMYOGRAPHY

Biomedical Engineering Applications Basis and Communications ◽

10.4015/s1016237209001258 ◽

2009 ◽

Vol 21 (03) ◽

pp. 193-199 ◽

Cited By ~ 1

Author(s):

Wensheng Hou ◽

Xiaoying Wu ◽

Jun Zheng ◽

Li Ma ◽

Xiaolin Zheng ◽

...

Keyword(s):

Surface Electromyography ◽

Force Production ◽

Neuromuscular Control ◽

Maximum Power ◽

Ar Model ◽

Force Level ◽

Hand Muscles ◽

Significant Difference ◽

Target Force ◽

Hand Muscle

Finger's action has been controlled by both intrinsic and extrinsic hand muscles. Characterizing the finger action with the activations of hand muscles could be useful for evaluating the neuromuscular control strategy of finger's motor functions. This study is designed to explore the correlation of isometric fingertip force production and frequency-domain features of surface electromyography (sEMG) recorded on extrinsic hand muscles. To this end, 13 subjects (five male and eight female university students) have been recruited to conduct a target force-tracking task. Each subject is required to produce a certain level of force with either the index or middle fingertip to match the pseudo-random ordered target force level (4N, 6N, or 8N) as accurate as possible. During the finger force production process, the sEMG signals are recorded on two extrinsic hand muscles: flex digitorum superficials (FDS) and extensor digitorum (ED). For each sEMG trail, the power spectrum is estimated with the autoregressive (AR) model and from which the maximum power is obtained. Our experimental results reveal three findings: (1) the maximum power increases with the force level regardless of the force producing finger (i.e. index or middle) and the extrinsic hand muscle (i.e. FDS or ED). (2) The sEMG maximum power of index finger is significantly lower than that of the middle finger under the same force level and extrinsic hand muscle. (3) No significant difference can be found between the maximum powers of FDS and ED. The results indicate that the activations of the extrinsic muscles are affected by both the force level and the force producing finger. Based on our findings, the sEMG maximum power of the extrinsic hand muscles could be used as a key parameter to describe the finger's actions.

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Learning a Novel Myoelectric-Controlled Interface Task

Journal of Neurophysiology ◽

10.1152/jn.90614.2008 ◽

2008 ◽

Vol 100 (4) ◽

pp. 2397-2408 ◽

Cited By ~ 88

Author(s):

Saritha M. Radhakrishnan ◽

Stuart N. Baker ◽

Andrew Jackson

Keyword(s):

Task Performance ◽

Motor System ◽

Two Dimensional ◽

Trained Subjects ◽

Flexible Control ◽

Hand Muscles ◽

Myoelectric Prostheses ◽

Control Signals ◽

Arm Muscles ◽

High Level

Control of myoelectric prostheses and brain–machine interfaces requires learning abstract neuromotor transformations. To investigate the mechanisms underlying this ability, we trained subjects to move a two-dimensional cursor using a myoelectric-controlled interface. With the upper limb immobilized, an electromyogram from multiple hand and arm muscles moved the cursor in directions that were either intuitive or nonintuitive and with high or low variability. We found that subjects could learn even nonintuitive arrangements to a high level of performance. Muscle-tuning functions were cosine shaped and modulated so as to reduce cursor variability. Subjects exhibited an additional preference for using hand muscles over arm muscles, which resulted from a greater capacity of these to form novel, task-specific synergies. In a second experiment, nonvisual feedback from the hand was degraded with amplitude- and frequency-modulated vibration. Although vibration impaired task performance, it did not affect the rate at which learning occurred. We therefore conclude that the motor system can acquire internal models of novel, abstract neuromotor mappings even in the absence of overt movements or accurate proprioceptive signals, but that the distal motor system may be better suited to provide flexible control signals for neuromotor prostheses than structures related to the arm.

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