Handedness, Dexterity, and Motor Cortical Representations

2011 ◽  
Vol 105 (1) ◽  
pp. 88-99 ◽  
Author(s):  
Jessica A. Bernard ◽  
Stephan F. Taylor ◽  
Rachael D. Seidler
Keyword(s):  
Motor Evoked Potentials ◽  
Behavioral Measures ◽  
Poffenberger Paradigm ◽  
First Dorsal Interosseous Muscle ◽  
Interhemispheric Transfer Time ◽  
Motor Cortical ◽  
Motor Representations ◽  
Cortical Representations ◽  
Contralateral Motor ◽  
Dorsal Interosseous Muscle

Motor system organization varies with handedness. However, previous work has focused almost exclusively on direction of handedness (right or left) as opposed to degree of handedness (strength). In the present study, we determined whether measures of interhemispheric interactions and degree of handedness are related to contra- and ipsilateral motor cortical representations. Participants completed a battery of handedness assessments including both handedness preference measures and behavioral measures of intermanual differences in dexterity, a computerized version of the Poffenberger paradigm (PP) to estimate interhemispheric transfer time (IHTT), and they underwent transcranial magnetic stimulation (TMS) mapping of both motor cortices while we recorded muscle activity from the first dorsal interosseous muscle bilaterally. A greater number of ipsilateral motor evoked potentials (iMEPs) were elicited in less lateralized individuals with the number of iMEPs correlated with IHTT. There were no relationships between handedness or lateralization of dexterity and symmetry of contralateral motor representations, although this symmetry was related to IHTT. Finally, IHTT was positively correlated with multiple measures of laterality and handedness. These findings demonstrate that degree of laterality of dexterity is related to the propensity for exhibiting iMEPs and the speed of interhemispheric interactions. However, it is not clear whether iMEPs are directly mediated via ipsilateral corticospinal projections or are transcallosally transmitted.

scholarly journals Do gaze behaviours during action observation predict interpersonal motor resonance?

2020 ◽  
Author(s):  
Soukayna Bekkali ◽  
George J Youssef ◽  
Peter H Donaldson ◽  
Jason He ◽  
Michael Do ◽  
...  
Keyword(s):  
Motor Evoked Potentials ◽  
Mirror Neuron System ◽  
Action Observation ◽  
Mirror Neuron ◽  
Motor Resonance ◽  
Action Execution ◽  
Neuron System ◽  
Biologically Relevant ◽  
First Dorsal Interosseous Muscle ◽  
Dorsal Interosseous Muscle

Abstract Interpersonal motor resonance (IMR) is a common putative index of the mirror neuron system (MNS), a network containing specialised cells that fire during both action execution and observation. Visual content inputs to the MNS, however, it is unclear whether visual behaviours mediate the putative MNS response. We aimed to examine gaze effects on IMR during action observation. Neurotypical adults (N = 99; 60 female) underwent transcranial magnetic stimulation, electromyography, and eye-tracking during the observation of videos of actors performing grasping actions. IMR was measured as a percentage change in motor evoked potentials (MEPs) of the first dorsal interosseous muscle during action observation relative to baseline. MEP facilitation was observed during action observation, indicating IMR (65.43%, SE = 11.26%, P < 0.001). Fixations occurring in biologically relevant areas (face/hand/arm) yielded significantly stronger IMR (81.03%, SE = 14.15%) than non-biological areas (63.92%, SE = 14.60, P = 0.012). This effect, however, was only evident in the first of four experimental blocks. Our results suggest that gaze fixation can modulate IMR, but this may be affected by the salience and novelty of the observed action. These findings have important methodological implications for future studies in both clinical and healthy populations.

Decreased corticospinal excitability after subthreshold 1 Hz rTMS over lateral premotor cortex

Neurology ◽  
2001 ◽  
Vol 57 (3) ◽  
pp. 449-455 ◽  
Author(s):  
Willibald Gerschlager ◽  
Hartwig R. Siebner ◽  
John C. Rothwell
Keyword(s):  
Motor Cortex ◽  
Parietal Cortex ◽  
Motor Evoked Potentials ◽  
Premotor Cortex ◽  
Corticospinal Excitability ◽  
First Dorsal Interosseous ◽  
First Dorsal Interosseous Muscle ◽  
The Right ◽  
Hand Area ◽  
Dorsal Interosseous Muscle

Objective: To study whether trains of subthreshold 1 Hz repetitive transcranial magnetic stimulation (rTMS) over premotor, prefrontal, or parietal cortex can produce changes in excitability of motor cortex that outlast the application of the train.Background: Prolonged 1 Hz rTMS over the motor cortex can suppress the amplitude of motor-evoked potentials (MEP) for several minutes after the end of the train. Because TMS can produce effects not only at the site of stimulation but also at distant sites to which it projects, the authors asked whether prolonged stimulation of sites distant but connected to motor cortex can also lead to lasting changes in MEP.Methods: Eight subjects received 1500 magnetic stimuli given at 1 Hz over the left lateral frontal cortex, the left lateral premotor cortex, the hand area of the left motor cortex, and the left anterior parietal cortex on four separate days. Stimulus intensity was set at 90% active motor threshold. Corticospinal excitability was probed by measuring the amplitude of MEP evoked in the right first dorsal interosseous muscle by single suprathreshold stimuli over the left motor hand area before, during, and after the conditioning trains.Results: rTMS over the left premotor cortex suppressed the amplitude of MEP in the right first dorsal interosseous muscle. The effect was maximized (approximately 50% suppression) after 900 pulses and outlasted the full train of 1500 stimuli for at least 15 minutes. Conditioning rTMS over the other sites did not modify the size of MEP. A control experiment showed that left premotor cortex conditioning had no effect on MEP evoked in the left first dorsal interosseous muscle.Conclusions: Subthreshold 1 Hz rTMS of the left premotor cortex induces a short-lasting inhibition of corticospinal excitability in the hand area of the ipsilateral motor cortex. This may provide a model for studying the functional interaction between premotor and motor cortex in healthy subjects and patients with movement disorders.

scholarly journals Proactive modulation of long-interval intracortical inhibition during response inhibition

2016 ◽  
Vol 116 (2) ◽  
pp. 859-867 ◽  
Author(s):  
Matthew J. Cowie ◽  
Hayley J. MacDonald ◽  
John Cirillo ◽  
Winston D. Byblow
Keyword(s):  
Evoked Potentials ◽  
Response Inhibition ◽  
Primary Motor Cortex ◽  
Motor Evoked Potentials ◽  
Motor Evoked Potential ◽  
Intracortical Inhibition ◽  
Task Context ◽  
Stop Trial ◽  
First Dorsal Interosseous Muscle ◽  
Dorsal Interosseous Muscle

Daily activities often require sudden cancellation of preplanned movement, termed response inhibition. When only a subcomponent of a whole response must be suppressed (required here on Partial trials), the ensuing component is markedly delayed. The neural mechanisms underlying partial response inhibition remain unclear. We hypothesized that Partial trials would be associated with nonselective corticomotor suppression and that GABAB receptor-mediated inhibition within primary motor cortex might be responsible for the nonselective corticomotor suppression contributing to Partial trial response delays. Sixteen right-handed participants performed a bimanual anticipatory response inhibition task while single- and paired-pulse transcranial magnetic stimulation was delivered to elicit motor evoked potentials in the left first dorsal interosseous muscle. Lift times, amplitude of motor evoked potentials, and long-interval intracortical inhibition were examined across the different trial types (Go, Stop-Left, Stop-Right, Stop-Both). Go trials produced a tight distribution of lift times around the target, whereas those during Partial trials (Stop-Left and Stop-Right) were substantially delayed. The modulation of motor evoked potential amplitude during Stop-Right trials reflected anticipation, suppression, and subsequent reinitiation of movement. Importantly, suppression was present across all Stop trial types, indicative of a “default” nonselective inhibitory process. Compared with blocks containing only Go trials, inhibition increased when Stop trials were introduced but did not differ between trial types. The amount of inhibition was positively correlated with lift times during Stop-Right trials. Tonic levels of inhibition appear to be proactively modulated by task context and influence the speed at which unimanual responses occur after a nonselective “brake” is applied.

Contralateral muscle activity and fatigue in the human first dorsal interosseous muscle

2008 ◽  
Vol 105 (1) ◽  
pp. 70-82 ◽  
Author(s):  
Marijn Post ◽  
Sibel Bayrak ◽  
Daniel Kernell ◽  
Inge Zijdewind
Keyword(s):  
Muscle Activation ◽  
Motor Evoked Potentials ◽  
Voluntary Activation ◽  
Fatigued Muscle ◽  
Before And After ◽  
First Dorsal Interosseous Muscle ◽  
Motor Excitability ◽  
Force Reduction ◽  
Voluntary Contractions ◽  
Dorsal Interosseous Muscle

During effortful unilateral contractions, muscle activation is not limited to the target muscles but activity is also observed in contralateral muscles. The amount of this associated activity is depressed in a fatigued muscle, even after correction for fatigue-related changes in maximal force. In the present experiments, we aimed to compare fatigue-related changes in associated activity vs. parameters that are used as markers for changes in central nervous system (CNS) excitability. Subjects performed brief maximal voluntary contractions (MVCs) with the index finger in abduction direction before and after fatiguing protocols. We followed changes in MVCs, associated activity, motor-evoked potentials (MEP; transcranial magnetic stimulation), maximal compound muscle potentials (M waves), and superimposed twitches (double pulse) for 20 min after the fatiguing protocols. During the fatiguing protocols, associated activity increased in contralateral muscles, whereas afterwards the associated force was reduced in the fatigued muscle. This force reduction was significantly larger than the decline in MVC. However, associated activity (force and electromyography) remained depressed for only 5–10 min, whereas the MVCs stayed depressed for over 20 min. These decreases were accompanied by a reduction in MEP, MVC electromyography activity, and voluntary activation in the fatigued muscle. According to these latter markers, the decrease in CNS motor excitability lasted much longer than the depression in associated activity. Differential effects of fatigue on (associated) submaximal vs. maximal contractions might contribute to these differences in postfatigue behavior. However, we cannot exclude differences in processes that are specific to either voluntary or to associated contractions.

The Use of Patterned Neuromuscular Stimulation to Improve Hand Function Following Surgery for Ulnar Neuropathy

1994 ◽  
Vol 19 (4) ◽  
pp. 430-433 ◽  
Author(s):  
T. PETTERSON ◽  
G. P. SMITH ◽  
J. A. OLDHAM ◽  
T. E. HOWE ◽  
R. C. TALLIS
Keyword(s):  
Ulnar Nerve ◽  
Single Case ◽  
Hand Function ◽  
Single Case Design ◽  
Neuromuscular Stimulation ◽  
Single Motor Unit ◽  
First Dorsal Interosseous Muscle ◽  
Hand Muscle ◽  
The Right ◽  
Dorsal Interosseous Muscle

A 60-year-old man with wasting and weakness of the right hand following ulnar nerve entrapment at the elbow was referred for electrotherapy. An ulnar nerve transposition had been performed 2 years previously. This had produced some improvement in nerve conduction without significantly improving hand muscle function. The right first dorsal interosseous muscle (FDI) was stimulated for 4 hours per day over a 6-week period with a stimulus pattern replicating the discharge of a single motor unit from a healthy, fatigued FDI (patterned neuromuscular stimulation or PNMS). The response was assessed using a single case design. Significant improvements in the strength and fatigue resistance of the FDI were observed, associated with improvements in general hand function. PNMS may be useful in restoring hand function in patients with muscle atrophy following entrapment neuropathy.

Restoration of the first dorsal interosseous muscle

2021 ◽  
Author(s):  
C. Jaloux ◽  
A. Mayoly ◽  
C. Philandrianos ◽  
E. Bougie ◽  
R. Legré
Keyword(s):  
First Dorsal Interosseous ◽  
First Dorsal Interosseous Muscle ◽  
Dorsal Interosseous Muscle
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