Difference in Activity in the Supplementary Motor Area Depending on Limb Combination of Hand-Foot Coordinated Movements

Abstract

Periodic interlimb coordination shows lower performance when the ipsilateral hand and foot (e.g., right hand and right foot) are simultaneously moved than when the contralateral hand and foot (e.g., right hand and left foot) are simultaneously moved. The present study aimed to investigate how brain activity that is related to the dependence of hand-foot coordination on limb combination, using functional magnetic imaging. Twenty-one right-handed subjects performed periodic coordinated movements of the ipsilateral or contralateral hand and foot in the same or opposite direction in the sagittal plane. Kinematic data showed that performance was lower for the ipsilateral hand-foot coordination than for the contralateral one. A comparison of brain activity between the same and opposite directions showed that there was a greater activation of supplementary motor area for ipsilateral hand-foot coordination as compared to that seen during contralateral hand-foot coordination. We speculate that this might reflect a difference in the degree of inhibition of the neural circuit that disrupts opposite directional movements between ipsilateral and contralateral hand-foot coordinated movements.

Keywords: fMRI; interlimb coordination; limb combination; percent signal change; supplementary motor area.

FIGURE 1

Experimental task. Periodic ipsilateral (Ipsi) or contralateral (Con) coordination of the hand and foot during same or opposite (OPP) directional movements.

FIGURE 2

Representative kinematic traces for the four tasks. Upper figures indicate ipsilateral hand–foot coordination. Lower figures indicate contralateral hand–foot coordination. Black and gray lines show wrist and ankle angles, respectively.

FIGURE 3

(A) The region in which BOLD activity is significantly different between tasks [(Ipsi-OPP) – (Ipsi-SAME)]. (B) The difference in percent signal change (PSC) between the opposite and same directional movement (white: contralateral, gray: ipsilateral) in the regions that was observed in the subtraction analysis. Higher numbers indicate stronger activity during the opposite directional movement compared to the same directional movement. Asterisk indicates the significant difference between (Con-OPP – Con-SAME) and (Ipsi-OPP – Ipsi-SAME; ^∗p < 0.05). Daggers indicate that the PSC of (Ipsi-OPP – Ipsi-SAME) was significantly greater than zero (††p < 0.01).