Distinct Temporospatial Interhemispheric Interactions in the Human Primary and Premotor Cortex during Movement Preparation

Abstract

The preparation of a voluntary unimanual action requires sequential processing in bihemispheric motor areas. In both animals and humans, activity in the dorsal premotor cortex (PMd) ipsilateral to the moving hand has been demonstrated to precede ipsilateral primary motor cortex (M1) activity. We investigated with double-pulse transcranial magnetic stimulation how right-hemispheric motor areas (rM1, rPMd) modulate left M1 (lM1) during the preparatory period of a finger movement with the dominant right hand. We tested the hypothesis that the influence of higher order motor areas such as rPMd on lM1 (rPMd-lM1) precedes interhemispheric interactions between homologue primary motor areas (rM1-lM1). rPMd-lM1 showed modulation in the early and late phase of movement preparation, whereas the intrinsic state of inhibition between rM1-lM1 was only modulated in the late phase. The present results complement existing hierarchical models of cortical movement control by demonstrating temporospatially distinct involvement of interhemispheric interactions from PMd and M1 during movement preparation.

Speed-Dependent Contribution of Callosal Pathways to Ipsilateral Movements

“…We found that ϳ90 ms before movement onset, IHI decreases during selfpaced and ballistic index finger and elbow movements compared to rest. This is in agreement with previous evidence showing that during the preparatory phase of ballistic movements IHI targeting the ipsilateral limb decreases compared to rest (Murase et al, 2004;Duque et al, 2005;Liuzzi et al, 2010). Previous studies demonstrated that interhemispheric sharing during a motor task modulates the speed of upcoming movements (Guiard and Requin, 1977).…”

“…Indeed, transcallosal inhibition progressively decreases during the preparatory phase of fast movements compared to rest (Murase et al, 2004;Duque et al, 2005;Liuzzi et al, 2010). The increases in movement speed also results in increments in electromyographic (EMG) activity during movement execution.…”

Vision Modulates Corticospinal Suppression in a Functionally Specific Manner during Movement of the Opposite Limb

“…Recent studies using TMS (and combined fMRI) in humans suggest a functional influence of (left) PMd upon the opposite PMd (and M1) that is strongly state dependent: varying in accordance with the nature of the task being performed by the ipsilateral limb (Bestmann et al, 2008). During movement preparation, there is a corresponding influence of (right) PMd on opposite M1, which precedes interhemispheric interactions between the homologous primary motor areas (Liuzzi et al, 2010). It is possible, therefore, that the state (i.e., vision)-dependent modulation of crossed facilitation observed in the present study was mediated via differential PMd control of interneuronal (i.e., inhibitory) circuitry within left and right M1.…”

A cognitive framework for explaining serial processing and sequence execution strategies

“…This neural structure, possibly aided by the basal ganglia (Stocco, Lebiere, & Anderson, 2010), organizes activity in regional networks by adjusting the functional connectivity across multiple cortical regions (Elsinger, Harrington, & Rao, 2006;Gelnar, Krauss, Sheehe, Szeverenyi, & Apkarian, 1999;Liuzzi et al, 2010;Roland, Larsen, Lassen, & Skinhoj, 1980). Furthermore, it also controls sensory input via the thalamus (Brunia, 1999).…”