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

    Strappini, F. and Pitzalis, S. and Snyder, A.Z. and McAvoy, M.P. and Sereno, Martin I. and Corbetta, M. and Shulman, G.L. (2015) Eye position modulates retinotopic responses in early visual areas: a bias for the straight-ahead direction. Brain Structure and Function 220 (5), pp. 2587-2601. ISSN 1863-2653.

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    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.

    Metadata

    Item Type: Article
    Keyword(s) / Subject(s): Gain field, Gaze, Retinotopy, Vertical meridian, Wide-field
    School: Birkbeck Schools and Departments > School of Science > Psychological Sciences
    Divisions > Birkbeck Schools and Departments > School of Science > Psychological Sciences
    Depositing User: Administrator
    Date Deposited: 23 Jun 2014 13:41
    Last Modified: 08 Jul 2020 11:27
    URI: http://eprints.bbk.ac.uk/id/eprint/10011

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