Luminance-contrast mechanisms in humans: visual evoked potentials and a nonlinear model
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Updated: Jul 15, 2026

Visualizing Visual Adaptation
Published on: April 24, 2017
1Ferkauf Graduate School of Psychology, Yeshiva University, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA. vepman@aol.com
Abstract:
Isolated-checks were luminance-modulated temporally to elicit VEPs. Bright or dark checks were used to drive ON or OFF pathways, and low or high-contrast conditions were used to emphasize activity from magnocellular or parvocellular pathways. Manipulation of stimulus parameters and frequency analysis of the VEP were performed to obtain spatial and contrast-response functions. A biophysical explanation is offered for why the opposite polarity stimuli drive selectively ON and OFF pathways in primary visual cortex, and a lumped biophysical model is proposed to quantify the data and characterize changes in the dynamics of the system with contrast given a limited number of parameters. Response functions were found to match the characteristics of the targeted pathways.
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