Abstract
To understand the functional difference between dominant and non-dominant limbs in human unipedal standing, we examined postural and electromyographic (EMG) responses to galvanic vestibular stimulation (GVS). EMG activities were recorded from muscles of ankle, knee, and hip joints of both limbs. Movement of center of pressure (COP) was recorded by a force plate. For GVS, electric DC current of 0.6 mA were applied for 5 second during standing. Kinematic analysis revealed that GVS induced displacement of head (frontal region), thorax (angulus sterni) and pelvis (spina iliaca anterior superior) positions toward the side of the anode, and the ankle position of the unloaded leg moved in the opposite direction. Resultantly, the COP changed its lateral position toward the anodal side. When the anode was put on the contralateral side to the supporting limb, displacements of the body positions were larger than those when the anode was ipsilaterally set. Correspondingly, GVS evoked activation of supporting limb muscles. When the anode was put on the ipsilateral side to the supporting limb, m. extensor digitorum longus (EDL, ankle evertor) was activated, followed by activation of m. tibialis anterior (TA, ankle flexor and adductor). The anode positioned contralaterally at first activated TA, then EDL. These results were common whether the supporting limb was dominant or not. Differences between dominant and non-dominant limbs are currently investigated in detail. [J Physiol Sci. 2008;58 Suppl:S194]
