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Estimation of cortical magnification from positional error in normally sighted and amblyopic subjects

Hussain, Z.
; 
Svensson, C-M.
; 
Besle, J.
; 
Webb, B.S.
; 
Barrett, Brendan T.
; 
McGraw, Paul V.
Publication Date
2015-02
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Keywords
Cortical magnification, Estimation, Positional error, Normally sighted, Amblyopic individuals
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© 2015 The Authors. Published by ARVO. Reproduced in accordance with the publisher's self-archiving policy under Creative Commons Attribution-NonCommercial-NoDerivatives License (http://creativecommons.org/licenses/bync-nd/4.0/legalcode)
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openAccess
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Abstract
We describe a method for deriving the linear cortical magnification factor from positional error across the visual field. We compared magnification obtained from this method between normally sighted individuals and amblyopic individuals, who receive atypical visual input during development. The cortical magnification factor was derived for each subject from positional error at 32 locations in the visual field, using an established model of conformal mapping between retinal and cortical coordinates. Magnification of the normally sighted group matched estimates from previous physiological and neuroimaging studies in humans, confirming the validity of the approach. The estimate of magnification for the amblyopic group was significantly lower than the normal group: by 4.4 mm deg 1 at 18 eccentricity, assuming a constant scaling factor for both groups. These estimates, if correct, suggest a role for early visual experience in establishing retinotopic mapping in cortex. We discuss the implications of altered cortical magnification for cortical size, and consider other neural changes that may account for the amblyopic results.
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http://hdl.handle.net/10454/10182
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Published version
Citation
Hussain Z, Svensson C-M, Besle J, Webb BS, Barrett BT and McGraw PV (2015) Estimation of cortical magnification from positional error in normally sighted and amblyopic subjects. Journal of Vision 15(2) 25: 1-16.
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https://doi.org/10.1167/15.2.25
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