Probing the neural mechanism of binocular information processing with VEPs

Abstract

AbstractWe analyze the binocular stereo‐vision process, and the visual evoked potential (VEP) is examined for the case in which a random‐dot stereogram (RDS) is presented. In this study, three experimental parameters are considered, namely, stimulus presentation position, disparity, and correlation between binocular images. The analysis is based on the change of VEP latency, and the relation between the binocular stereo‐vision process and the binocular competition process is investigated. The VEP waveform for RDS presentation is divided into three main components. The first component is the initial vision response, observed to be localized in the occipital area, which is considered to reflect the local disparity detection process. The second and third components are responses with middle to long latency spreading from the occipital area to the frontal areas, and the latency greatly depends on the presentation position and the disparity. The latency is shorter when the presentation is at the center than at the periphery of the view field, and is shorter for crossed disparity than for uncrossed disparity. The difference of latency seems to reflect the processing mechanisms for the presentation position and the disparity. In an experiment using the RDS with the contrast reversed between two eyes (anti‐RDS), the latency is longer for crossed disparity than for uncrossed disparity, which is the reverse of the case of RDS. This phenomenon can be accounted for by the response of the disparity‐selective neuron in V1, which suggests that both binocular stereo vision and binocular competition are based on the local disparity detection mechanism as the neural basis. The response of the disparity‐selective neuron is simulated using the binocular energy model, and the difference between the two kinds of binocular vision processing. A mechanism that detects the unpairedness between the two eyes is proposed. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 86(3): 47–60, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10135