Eye position modulates retinotopic responses in early visual areas: a bias for the straight-ahead directionReport as inadecuate




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Brain Structure and Function

, Volume 220, Issue 5, pp 2587–2601

First Online: 19 June 2014Received: 11 December 2013Accepted: 21 May 2014

Abstract

Even though the eyes constantly change position, the location of a stimulus can be accurately represented by a population of neurons with retinotopic receptive fields modulated by eye position gain fields. Recent electrophysiological studies, however, indicate that eye position gain fields may serve an additional function since they have a non-uniform spatial distribution that increases the neural response to stimuli in the straight-ahead direction. We used functional magnetic resonance imaging and a wide-field stimulus display to determine whether gaze modulations in early human visual cortex enhance the blood-oxygenation-level dependent BOLD response to stimuli that are straight-ahead. Subjects viewed rotating polar angle wedge stimuli centered straight-ahead or vertically displaced by ±20° eccentricity. Gaze position did not affect the topography of polar phase-angle maps, confirming that coding was retinotopic, but did affect the amplitude of the BOLD response, consistent with a gain field. In agreement with recent electrophysiological studies, BOLD responses in V1 and V2 to a wedge stimulus at a fixed retinal locus decreased when the wedge location in head-centered coordinates was farther from the straight-ahead direction. We conclude that stimulus-evoked BOLD signals are modulated by a systematic, non-uniform distribution of eye-position gain fields.

KeywordsGain field Gaze Retinotopy Vertical meridian Wide-field Electronic supplementary materialThe online version of this article doi:10.1007-s00429-014-0808-7 contains supplementary material, which is available to authorized users.

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Author: Francesca Strappini - Sabrina Pitzalis - Abraham Z. Snyder - Mark P. McAvoy - Martin I. Sereno - Maurizio Corbetta - Gord

Source: https://link.springer.com/



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