Human primary visual cortex shows larger population receptive fields for binocular disparity-defined stimuli

Abstract

The visual perception of 3D depth is underpinned by the brain’s ability to combine signals from the left and right eyes to produce a neural representation of binocular disparity for perception and behaviour. Electrophysiological studies of binocular disparity over the past 2 decades have investigated the computational role of neurons in area V1 for binocular combination, while more recent neuroimaging investigations have focused on identifying specific roles for different extrastriate visual areas in depth perception. Here we investigate the population receptive field properties of neural responses to binocular information in striate and extrastriate cortical visual areas using ultra-high field fMRI. We measured BOLD fMRI responses while participants viewed retinotopic mapping stimuli defined by different visual properties: contrast, luminance, motion, correlated and anti-correlated stereoscopic disparity. By fitting each condition with a population receptive field model, we compared quantitatively the size of the population receptive field for disparity-specific stimulation. We found larger population receptive fields for disparity compared with contrast and luminance in area V1, the first stage of binocular combination, which likely reflects the binocular integration zone, an interpretation supported by modelling of the binocular energy model. A similar pattern was found in region LOC, where it may reflect the role of disparity as a cue for 3D shape. These findings provide insight into the binocular receptive field properties underlying processing for human stereoscopic vision.

Investigating the human binocular visual system using multi-modal magnetic resonance imaging

“…When a disparity-defined stimulus is used for mapping the visual areas compared to a flickering checkerboard, the pRF sizes are larger for the disparity-defined stimulus by an amount predicted by computational models of binocular combination. All adapted from Alvarez et al (2021). of depth. Neurophysiological studies have indicated that neurons in primary visual cortex respond to the false matches in aRDS patterns (Cumming & Parker, 1997) but the response to these patterns is significantly reduced higher within the ventral visual stream, notably in V4 and IT (Janssen et al, 2003;Tanabe et al, 2004).…”

“…When a disparity-defined stimulus is used for mapping the visual areas compared to a flickering checkerboard, the pRF sizes are larger for the disparity-defined stimulus by an amount predicted by computational models of binocular combination. All adapted from Alvarez et al (2021).…”

“…Binocular neurons need to receive signals from retinal positions that are slightly offset from one another to perform disparity calculations at the earliest level of input. Using the technique of pRF mapping (Figure 3), which allows a receptive field to be estimated for a given voxel in the brain, Alvarez et al (2021) mapped the visual cortex at high spatial resolution (1.2 mm isotropic resolution) using stimuli defined by checkerboards, contrast reversing dots, motion and binocular disparity. When a binocular, disparity-defined stimulus was used, the pRF size in V1 was larger than when the stimuli contained only zero disparity (Figure 3C), suggesting that the disparity-responsive receptive fields in V1 are increased due to the offset of the receptive fields in the two eyes.…”

Understanding structure–function relationships in the mammalian visual system: part one

“…Three other papers explore the functional properties of V1 and how they change according to different conditions. Alvarez et al (2021) report that human V1 shows larger population receptive fields (pRF; Dumoulin and Wandell 2008) for disparity-defined stimuli, compared with other types of stimuli, and that this observation can be explained based on the binocular energy model (Ohzawa et al 1990). Further, Silva et al (2021) report that pRF estimates are affected by aging, revealing correlations between visual acuity, retinal thickness, and cortical visual area size in human participants.…”

The matching rule of Panum’s limiting case and its influencing factors

“…In general, there is a certain difference in the image position of the corresponding features presented to the retina of both eyes due to the horizontal distance between the eyes, called binocular disparity (Angelis et al, 1995;Gonzalez and Perez, 1998;Alvarez et al, 2021). If the corresponding image point can be found on both retinas, this disparity in position can be retrieved, and the relative depth of the object can be measured (Tsirlin et al, 2014;Verhoef et al, 2016;Chen et al, 2021;Vishwanath, 2021).…”