1981 年 40 巻 2 号 p. 242-250
The effects of horizontal and vertical optokinetic stimulation on head movement in neuro-otologically normal adults were investigated by using an optokinetic stimulator of Jung type, a cephalograph and a minicomputer. The cephalograph consisted of a lightemitting diode (LED) on the helmet and an industrial television system to pursue the movement of LED on the horizontal plane, an X-Y recorder and a data recorder. Computer analyses were performed with an off-line system.
The followilg results were obtained.
When the speed of optokinetic stimulation was increased the locus traced by the head movement and the total length of the locus gradually increased up to 60 deg/sec and then decreased. There was a standard two-phasic course in the position of the head movement. The ratio of the antero-posterior component to the lateral component of the head movement was below the control value with horizontal optokinetic stimulation, while with vertical stimulation it was over the control, showing a striking peak at 60 deg/sec of optokinetic stimulation. Spectral frequencies of the head movement showed two types of change. Type I showed a frequency shift to a higher division within the range below 1 Hz during optokinetic stimulation, while Type II revealed a peak at 0.2 to 0.3 Hz with 30 to 90 deg/sec of stimulation. The difference between the two types was manifest in the calculated averaged divisional frequencies of below 1 Hz.