Item

Abstract

The retinotopic organization of visual cortex has been extensively studied in primates and other mammals with the notion of the receptive field (RF) playing a major contribution to neuroscientific research in general. Although a wealth of information has been acquired from studies in cats, non-human primates, et cetera, which led to explicit understanding of the organization of primary visual cortex and the development of analytical formulations to describe the projection from the retina to the cortical space, RF sizes have not been accurately estimated in human V1. Recent studies substantially advanced this field of research by using novel neuro-computational methods. A prime example of such methods is the estimation of population receptive fields (pRFs) in retinotopically organized visual areas. However, pRFs are only estimates of aggregate
voxel-based averages of ten to hundreds of thousands of neurons within fMRI voxels and are a function of: (a) the receptive field properties of single units belonging to a voxel, (b) the scatter in the location of receptive field centres across units, and (c) the interactions between
nearby connected units. Here, we present a novel approach to estimate the average single-neuron receptive field sizes
in human primary visual cortex. To this end, we exploit the spatial-frequency dependent fMRI responses of visual RFs modeled as Gabor functions. Furthermore, we validate non-invasive RF size estimates obtained using the same fMRI method in non-human primates by comparing them directly with RF sizes obtained via intracranial electrophysiological recordings.