Intra- and Inter-person Coordinated Movements of Fingers and Toes

Abstract

When performing intra- or inter-person coordination of cyclical movements of two joints, there is a perceptual-cognitive constraint based on spatial information for performing such coordination. However, bimanual coordination of the index finger flexion-extension is an exception in which the constraint occurs based on motoric information, which might be peculiar to digits. In order to investigate whether intra- and inter-person coordination of fingers and toes were constrained based on spatial or motoric information, coordinated movements were performed in one of two modes, flexing fingers concomitant with either toe flexion or toe extension, with the forearm either in the pronated or supinated position. In intra-person coordination, both the relative direction of movement and activation coupling influenced the stability of coordination to a similar extent. In inter-person coordination, the coordination with alternate activation of the corresponding muscles of fingers and toes in the opposite direction was less stable as compared to other coordination modes. These findings suggest that both spatial and motoric information are utilized in intra-person coordination of the fingers and toes, whereas either spatial or motoric information is utilized in inter-person coordination to meet a specific requirement for each task.