覚醒水準に依存する視覚誘発サッケードの特性解析

脳波の同時計測にもとづく図形弁別課題負荷時と無負荷時の比較

抄録

The purpose of this study is to investigate effects of vigilance states on the characteristics of visually triggered saccade quantitatively. In this paper saccades and EEG at three position on the scalp of Fz, Cz and Pz have been measured in two different experimental conditions: target discrimination task (Task) and Non-Task. In Task condition subjects chased a target, then discriminated the figure of it and put the button when the target was triangle. In Non-Task condition subjects only chased a spot target. EEG data obtained from both conditions were analyzed by means of Fast Fourier Transform and two parameters of vigilance states were extracted from the spectral power of EEG. Comparison of the vigilance state parameters and the saccade parameters between two conditions showed that in Task condition, vigilance states were higher, saccade latencies were shorter, saccade absolute position errors were smaller, saccade durations were shorter, and saccade peak velocities were faster than in Non-Task condition. These results imply that the rise in vigilance state in Task condition may have changed the characteristics of saccade. In order to examine this possibility, data of saccades were divided to high vigilance group and low vigilance group according to the value of EEG parameters. The results indicated that saccade latencies and durations became shorter and saccade peak velocities faster due to the rise in vigilance state. These facts suggest that new EEG parameters we proposed reflect vigilance states quantitatively and these are practical for analysis of saccades, and that the characteristics of saccade have a dependence on vigilance states.