Effects of optokinetic stimulation on the center of gravity during standing.

The effects of horizontal as well as vertical optokinetic stimuli on the body's center of gravity in normal adults were investigated by using Jungtype optokinetic stimulator, a straingage platform and a minicomputer. The following results were obtained. With increasing speed of the optokinetic stimulation, the total length of the center of gravity gradually increased up to 60 deg/sec and then decreased. Meanwhile there was a standard two-phasic course in the position of the center of gravity. The ratio of the anteroposterior component to the lateral component in the movement of the center of gravity was below 1.00 in horizontal optokinetic stimulation, while in vertical stimulation it was over 1.00 and showed the maximum deviation of the position at about 60 deg/sec of optokinetic stimulation. The frequency spectra of the movement of the center of gravity showed some peaks at around 0.3 Hz and 1.0 Hz during optokinetic stimulation. The averaged divisional frequencies were calculated to show the change in the frequency spectra in digital values.