Stereoscopic evoked responses to crossed and uncrossed disparity accompanying simulated refractive error

Modulation of human visual evoked potentials in 3-dimensional perception after stimuli produced with an integral imaging method

We investigated the neurophysiological correlates of stereoscopic 3-dimensional (3-D) depth perception by studying human visual evoked potentials (VEPs) with an integral imaging method characterized by horizontal but not vertical disparity. The VEPs were recorded in 10 healthy men under 4 conditions. In condition I, stimuli A (flat, 2-dimensional [2-D] image) and B (concave 3-D image) were presented at random. In condition II, stimuli A and C (convex 3-D image) were presented at random. In condition III, stimuli B and C were presented at random. In condition IV, stimuli A, B, and C were presented at random. The data for flat VEPs to stimulus A were combined in conditions I and II. The data for concave VEPs to stimulus B were combined in conditions I and III. The data for convex VEPs to stimulus C were combined in conditions II and III. When 2-way analysis of variance (ANOVA) for 2 factors, stimulus conditions (flat VEPs, concave VEPs, and convex VEPs) and electrode positions, was applied for VEP data, the N1 and N2 peak amplitudes differed significantly among the 3 stimulus conditions. In condition IV, the N1 peak amplitudes differed significantly among the 3 stimuli. Multiple comparisons followed by Bonferroni adjustment did not detect differences in the N1 peak amplitude between stimuli A and B, between stimuli A and C, or between stimuli B and C. We concluded that VEPs to concave or convex 3-D stimuli were significantly different from VEPs to flat 2-D stimuli. This is the first report showing modulation of human VEPs in 3-D perception with an integral imaging method.

Discrimination of motion in depth trajectory following acute alcohol ingestion

Evoked potentials were recorded at four scalp sites O1, O2, T5, T6; before and after the consumption of one of two alcohol dose levels, to the occurrence of disparate stimuli in dynamic random dot stereograms. Twenty young adult subjects, all of whom had vision which was normal or corrected to normal, were randomly assigned to the two dosage groups. Subjects viewed stimuli which embodied crossed disparity and followed one of three trajectories in depth. The task was to distinguish between and identify, by specific button presses, these trajectories. One half of the stimuli were presented with monocular cues to motion in depth (dark condition); in the remainder only stereoscopic depth information was available (uniform condition). Responses to both conditions showed alcohol-related reduction of evoked responses across all sites. It was concluded that the visual systems associated with the processing of motion in depth were susceptible to alcohol effects, as revealed by reductions in the amplitude of evoked responses.