Purchase this article with an account.
Ana Leticia Ramirez Hernandez, Ari Rosenberg, Curtis L. Baker; Y-like human psychophysical responses to contrast modulated patterns. Journal of Vision 2021;21(9):2230. doi: https://doi.org/10.1167/jov.21.9.2230.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Cat Y-type retinal ganglion cells (RGCs) and macaque parasol cells are distinguished by responding nonlinearly to high spatial frequencies (SFs) and temporal frequencies (TFs). However, the contribution of these RGCs to human visual perception are not well understood. Here we devised a psychophysical approach to reveal the function of human Y-like RGCs. We take advantage of the Y-like carrier response properties of cortical neurons to contrast modulated (CM) patterns which consist of a high SF contrast-reversing grating carrier whose contrast is modulated by a low SF drifting sinewave envelope (0.25 cpd, 3 Hz). In each stimulus trial, subjects reported the direction of motion of CM envelopes or luminance modulated (LM) gratings at 2.1, 4.3, 6.4, or 8.5 degrees of eccentricity. Within each block of trials, SF (for LMs) or carrier SF (for CMs) was varied with the method of constant stimuli for different values of TF (LMs) or carrier TF (CMs). We found that the best performance for LM patterns was at lower TFs (5-10 Hz) and at lower SFs, which decreased systematically with eccentricity. However, CM pattern performance was bandpass with carrier SF, displaying the best performance at 1.5-3.0 cpd, and high carrier TFs (15-20 Hz). At the highest carrier TF (20 Hz), performance did not decrease systematically with eccentricity. The nonlinear subunits of Y-type cells respond better at higher TFs than linear mechanisms respond to gratings. Therefore, the measured psychophysical performance for CM patterns is consistent with nonlinear subunits. Furthermore, the good performance at SFs that are high for peripheral vision and rather independent of eccentricity is more consistent with the responses of small nonlinear subunits than with linear mechanisms.
This PDF is available to Subscribers Only