Dynamics of absolute and relative disparity processing in human visual cortex

Milena Kaestner; Marissa L. Evans; Yulan D. Chen; Anthony M. Norcia

NeuroImage (Jul 2022)

Dynamics of absolute and relative disparity processing in human visual cortex

Milena Kaestner,
Marissa L. Evans,
Yulan D. Chen,
Anthony M. Norcia

Affiliations

Milena Kaestner: Wu Tsai Neurosciences Institute, Stanford University, 290 Jane Stanford Way, Stanford, CA, USA; Department of Psychology, Stanford University, 450 Jane Stanford Way, Stanford, CA, USA; Corresponding author at: Wu Tsai Neurosciences Institute, Stanford University, 290 Jane Stanford Way, Stanford, CA, USA.
Marissa L. Evans: Wu Tsai Neurosciences Institute, Stanford University, 290 Jane Stanford Way, Stanford, CA, USA; Department of Psychology, Stanford University, 450 Jane Stanford Way, Stanford, CA, USA
Yulan D. Chen: Wu Tsai Neurosciences Institute, Stanford University, 290 Jane Stanford Way, Stanford, CA, USA; Department of Psychology, Stanford University, 450 Jane Stanford Way, Stanford, CA, USA
Anthony M. Norcia: Wu Tsai Neurosciences Institute, Stanford University, 290 Jane Stanford Way, Stanford, CA, USA; Department of Psychology, Stanford University, 450 Jane Stanford Way, Stanford, CA, USA

Journal volume & issue: Vol. 255
p. 119186

Abstract

Read online

Cortical processing of binocular disparity is believed to begin in V1 where cells are sensitive to absolute disparity, followed by the extraction of relative disparity in higher visual areas. While much is known about the cortical distribution and spatial tuning of disparity-selective neurons, the relationship between their spatial and temporal properties is less well understood. Here, we use steady-state Visual Evoked Potentials and dynamic random dot stereograms to characterize the temporal dynamics of spatial mechanisms in human visual cortex that are primarily sensitive to either absolute or relative disparity. Stereograms alternated between disparate and non-disparate states at 2 Hz. By varying the disparity-defined spatial frequency content of the stereograms from a planar surface to corrugated ones, we biased responses towards absolute vs. relative disparities. Reliable Components Analysis was used to derive two dominant sources from the 128 channel EEG records. The first component (RC1) was maximal over the occipital pole. In RC1, first harmonic responses were sustained, tuned for corrugation frequency, and sensitive to the presence of disparity references, consistent with prior psychophysical sensitivity measurements. By contrast, the second harmonic, associated with transient processing, was not spatially tuned and was indifferent to references, consistent with it being generated by an absolute disparity mechanism. Thus, our results reveal a duplex coding strategy in the disparity domain, where relative disparities are computed via sustained mechanisms and absolute disparities are computed via transient mechanisms.

Published in NeuroImage

ISSN: 1053-8119 (Print); 1095-9572 (Online)
Publisher: Elsevier
Country of publisher: United States
LCC subjects: Medicine: Internal medicine: Neurosciences. Biological psychiatry. Neuropsychiatry
Website: https://www.journals.elsevier.com/neuroimage

About the journal

Abstract

Keywords