Abstract
Humans show a remarkable capacity to control a variety of motor outputs, ranging from writing with pencils to putting a shot. Controlling a motor output from the preferred hand is made by the descending signals from the primary motor cortex. With respect to motor outputs in humans, the issue of hemispheric specialization is closely tied to handedness and it linked to asymmetric brain functions. Left hemisphere dominance for the movement has been attributed to a functional asymmetry of M1 and descending pathways. However, some neuroimaging studies have found bilateral M1 activations either during unimanual tasks. In the present study, we discussed the muscle force control by the bilateral hemisphere.