Intermanual Differences in Movement-related Interhemispheric Inhibition

Abstract

Abstract& Interhemispheric inhibition (IHI) between motor cortical areas is thought to play a critical role in motor control and could influence manual dexterity. The purpose of this study was to investigate IHI preceding movements of the dominant and nondominant hands of healthy volunteers. Movement-related IHI was studied by means of a double-pulse transcranial magnetic stimulation protocol in right-handed individuals in a simple reaction time paradigm. IHI targeting the motor cortex contralateral (IHI c ) and ipsilateral (IHI i ) to each moving finger was determined. IHI c was comparable after the go signal, a long time preceding movement onset, in both hands. Closer to movement onset, IHI c reversed into facilitation for the right dominant hand but remained inhibitory for left nondominant hand movements.

Age-related differences in corticospinal excitability during a choice reaction time task

“…Recent work from Fujiyama et al (2012a, b) reports that an increased capacity to regulate inhibitory function was positively associated with better performance levels in older adults. It is noteworthy that previous studies already showed that preparatory suppression might be manifested at the cortical level, including inhibitory processes in the contralateral motor area (Duque et al 2007;Hinder et al 2010;Talelli et al 2008). Additionally, the involvement of higher order motor areas such as the dorsal premotor cortex cannot be ruled out (Duque et al 2012).…”

Tracking post-error adaptation in the motor system by transcranial magnetic stimulation

“…Also, magnetoencephalographic recordings of movement-related fields have demonstrated a bilateral activation of motor areas at about 500 ms prior to self-paced unilateral movements (Cheyne et al, 1991;Salmelin et al, 1995;Tandonnet et al, 2003). Nevertheless, previous TMS studies have yielded contradicting results showing that the excitability of the hemisphere ipsilateral to a movement was increased (Hoshiyama et al 1996;Muellbacher et al, 2000), decreased (Leocani et al, 2000;Duque et al, 2007) or unchanged during the performance of unilateral movements (MacKinnon and Rothwell, 2000). However, in a recent study Tandonnet et al (2010) showed that the amplitude of the MEP decreased for the ipsilateral motor cortex (corresponding to the non-responding hand in a choice reaction time paradigm) after 130 ms poststimulus presentation.…”

“…A second important limitation of this study is that these results are mainly based on the transcallosal modulation hypothesis, which has not been yet fully demonstrated and it should be taken carefully. In this context, inter-hemispheric inhibition measured through paired-pulse techniques between the right and the left primary motor areas (Duque et al, 2005;Duque et al, 2007;Vercauteren et al, 2008) might allow translating the increase (decrease) of MEP amplitudes measured following errors (correct) into a decrease (increase) of transcallosal suppression over the M1 contralateral to the responding hand. A third caveat corresponds to the lack of knowledge of the modulation of the excitability of the motor system measured by delivering pulses on the motor cortex contralateral to the active hand.…”

“…Transcranial magnetic stimulation (TMS) has been used to study changes in the excitability of the motor system during the execution of cognitive tasks that involve a motor command (Duque et al, 2005;Duque et al, 2007;van den Wildenberg et al, 2009). Commonly, suprathreshold single-pulses are given in primary motor areas to elicit motor evoked potentials (MEP) in hand muscles contralateral to the stimulation site.…”

Computational models and motor learning paradigms: Could they provide insights for neuroplasticity after stroke? An overview

“…The activity of the two hemispheres is balanced by means of "silent" inhibition guaranteed by the fibres in the corpus callosum, and this inhibition process can be impaired as a consequence of stroke [34]. As an example, in finger movement tasks, the M1 area increases its inhibition towards the injured hemisphere through the connections of the corpus callosum causing a decrease in excitability [35]. Studies in patients after stroke reported an increase in M1 area activity and abnormal inhibition in the damaged part, resulting from an imbalance in activity between the two brain hemispheres [36].…”