Sensitivity to the visual field origin of natural image patches in human low-level visual cortex.

Damien J Mannion

doi:10.7717/peerj.1038

Abstract

Asymmetries in the response to visual patterns in the upper and lower visual fields (above and below the centre of gaze) have been associated with ecological factors relating to the structure of typical visual environments. Here, we investigated whether the content of the upper and lower visual field representations in low-level regions of human visual cortex are specialised for visual patterns that arise from the upper and lower visual fields in natural images. We presented image patches, drawn from above or below the centre of gaze of an observer navigating a natural environment, to either the upper or lower visual fields of human participants (n = 7) while we used functional magnetic resonance imaging (fMRI) to measure the magnitude of evoked activity in the visual areas V1, V2, and V3. We found a significant interaction between the presentation location (upper or lower visual field) and the image patch source location (above or below fixation); the responses to lower visual field presentation were significantly greater for image patches sourced from below than above fixation, while the responses in the upper visual field were not significantly different for image patches sourced from above and below fixation. This finding demonstrates an association between the representation of the lower visual field in human visual cortex and the structure of the visual input that is likely to be encountered below the centre of gaze.

Highlights

There are numerous reports of asymmetries in the visual system’s representation of the upper and lower visual fields
Because there was little evidence to indicate that this interaction depended on the visual area (F1.9,11.4 = 1.52,p = 0.260), we combined across the visual areas (V1, V2, and V3) for subsequent analyses
Our hypothesis was partially supported; the response in low-level human visual cortex to natural image patches depended on whether the patches were presented in the same visual field location from which they were sourced—but only for presentation in the lower visual field and not in the upper visual field

Summary

Introduction

There are numerous reports of asymmetries in the visual system’s representation of the upper and lower visual fields (that is, above and below an imaginary horizontal line that passes through the centre of gaze). Behavioural asymmetries between the upper and lower visual fields have been reported for a variety of visual tasks and stimuli (see Previc, 1990; Danckert & Goodale, 2003; Karim & Kojima, 2010, for reviews). Differences between the upper and lower visual fields have been reported for binocular rivalry (Chen & He, 2003), pointing at targets (Danckert & Goodale, 2001), and crowding (He, Cavanagh & Intriligator, 1996). The representations of the upper and lower visual fields in the low-level areas of human visual cortex have.

Methods

Results

Conclusion