音像定位能力に対する垂直視運動刺激の影響

Abstract

Using dichotic sound, the effects of optokinetic vertical stimulation on the orientation of horizontal sound lateralization was investigated in 10 healthy subjects. Subjects were given vertical optokinetic (OK) stimulation, and interaural time differences (ITD) and interaural intensity differences (IID) were discriminated, respectively. At a light stripes velocity of 90°/sec, the amplitudes for the ITD discrimination tests during OK stimulation were significantly greater than those before the beginning of OK stimulation, those at a light stripes velocity of 30°/sec, and those at a light stripes accelerated velocity of 4°/sec2 (P<0.05). On the other side, at a light stripes velocity of 90°/ sec, the amplitudes for the IID discrimination tests during OK stimulation were only significantly greater than those at a light stripes accelerated velocity of 4°/sec2 (P<0.05). The median line of amplitude for both ITD and IID discrimination tests did not shift at a light stripes velocity of 30°/sec, 90°/sec, and 4°/sec2. The present study demonstrated that sound horizontal lateralization sensitivity may be influenced by vertical OK stimulation. These findings also suggest that horizontal sound lateralization is more dependent on high-speed vertical OK stimulation than low-speed vertical OK stimulation. Therefore, we hypothesized that there is some interaction between the subcortical pathway of high-speed vertical OK stimulation and the sound lateralization pathway. The results of the present study will help in the understanding of space perception, comprising multiple sensory inputs.