Direct comparison of contralateral bias and face/scene selectivity in human occipitotemporal cortex

Edward H Silson,Iris I A Groen,Chris I Baker

doi:10.1007/s00429-021-02411-8

Abstract

Human visual cortex is organised broadly according to two major principles: retinotopy (the spatial mapping of the retina in cortex) and category-selectivity (preferential responses to specific categories of stimuli). Historically, these principles were considered anatomically separate, with retinotopy restricted to the occipital cortex and category-selectivity emerging in the lateral-occipital and ventral-temporal cortex. However, recent studies show that category-selective regions exhibit systematic retinotopic biases, for example exhibiting stronger activation for stimuli presented in the contra- compared to the ipsilateral visual field. It is unclear, however, whether responses within category-selective regions are more strongly driven by retinotopic location or by category preference, and if there are systematic differences between category-selective regions in the relative strengths of these preferences. Here, we directly compare contralateral and category preferences by measuring fMRI responses to scene and face stimuli presented in the left or right visual field and computing two bias indices: a contralateral bias (response to the contralateral minus ipsilateral visual field) and a face/scene bias (preferred response to scenes compared to faces, or vice versa). We compare these biases within and between scene- and face-selective regions and across the lateral and ventral surfaces of the visual cortex more broadly. We find an interaction between surface and bias: lateral surface regions show a stronger contralateral than face/scene bias, whilst ventral surface regions show the opposite. These effects are robust across and within subjects, and appear to reflect large-scale, smoothly varying gradients. Together, these findings support distinct functional roles for the lateral and ventral visual cortex in terms of the relative importance of the spatial location of stimuli during visual information processing.

Highlights

Visual cortex in each hemisphere initially receives visual inputs from different parts of the visual field, whereby the left visual field is mapped onto the right hemisphere and Edward H
These two organising principles have historically been thought of as anatomically separate, with retinotopy considered predominant in posterior, early visual cortex (EVC) and category-selectivity considered predominant in the relatively more anterior, lateraloccipital cortex (LOTC) and ventral-occipitotemporal cortex (VOTC), respectively (Op de Beeck et al 2019)
Using a systematic test of the visual field and category biases we demonstrate that while scene- and face-selective regions in LOTC and VOTC exhibit both types of biases, there is a striking difference in the predominant bias from contralateral in LOTC to category in VOTC

Summary

Introduction

Visual cortex in each hemisphere initially receives visual inputs from different parts of the visual field, whereby the left visual field is mapped onto the right hemisphere and Edward H. Another key organising principle of the visual cortex is category-selectivity, which describes the phenomenon that some brain regions respond more strongly to the sight of. Categoryselective regions were originally identified in cortical locations more anterior to the first retinotopic maps in the hierarchy (V1, V2 and V3). As a result, these two organising principles have historically been thought of as anatomically separate, with retinotopy considered predominant in posterior, early visual cortex (EVC) and category-selectivity considered predominant in the relatively more anterior, lateraloccipital cortex (LOTC) and ventral-occipitotemporal cortex (VOTC), respectively (Op de Beeck et al 2019). Systematic comparisons of higher-order retinotopic maps and category-selective regions show considerable overlap (Larsson and Heeger 2006; Sayres and Grill-Spector 2008; Arcaro et al 2009; Silson et al 2016)

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Conclusion