正常人不同视差刺激时静态视差诱发电位分析

THE ANALYSIS OF STATIC DISPARITY EVOKED POTENTIALS BY DIFFER-ENT DISPARATE STIMULI IN NORMAL SUBJECTS

用静态随机点立体图作视刺激，对４０名正常人在不同视差（２’、７’、１４’、２３’、３６’、４６’、９２’、１３８’和２３０’）状态下进行视诱发电位检测。结果：不同视差刺激时在２５０ｍｓ左右记录到宽大的正波（即Ｐ（２５０）波）；精细视差（＜２３’）和粗略视差（２４６’）刺激时的诱发电位波形不同，分别出现一次振幅高峰，揭示人类立体视觉存在相互独立的精细与粗略视差加工机制。

A new set of static random-dot stereograms(RDS)free of monocular clues was uti-lized as stimulus to elicit disparity evoked potentials(DEP)in 40normal subjects.The DEP of every suject was recorded in different disparate stimuli(2’、7’、14’、23’、36’、46’、92’、138’and 230’of arc)and compared with recordings of non-disparate stimulus.A characteristic wide positive wave at about 250ms,which may be regard as evidence of the presence of stereopsis,was consistently recorded in different disparate stimuli and not in non-disparate stimulus,This wave was called P(250)wave,The amplitude of P(250) wave was changed depending on the disparities. There were two ampli-tude peaks in 14’and 92’.And the form of P(250) wave in large disparitites(>46’)was diffrent from the small disparities(<36’).The data should imply that disparity processing mechanisms either un-dergo dynamic changes as disparity increase or that processing shift between at least two indepen-dent mechanisms.