RESEARCH ARTICLE


The Cortical Topography of Visual Evoked Potentials Elicited by Chromatic and Luminance Motion



E.G Laviers, M.P Burton, D.J McKeefry*
Vision Science Research Group, School of Life Sciences, University of Bradford, Richmond Road, Bradford BD7 1DP, UK


2007 Bentham Science Publishers Ltd.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.5/) which permits unrestrictive use, distribution, and reproduction in any medium, provided the original work is properly cited.

* Address correspondence to this author at the Division of Optometry, School of Life Sciences, University of Bradford, Bradford, BD7 1DP, UK; Tel: +44 (0)1274 234648; Fax: +44 (0)1274 235570; E-mail: d.mckeefry@bradford.ac.uk


Abstract

When motion-onset VEPs are elicited by moving luminance patterns, the motion specific component of the response, N2, is more prominent at electrode sites that overlay the lateral occipito-parietal cortex close to area V5/MT, than over the primary visual cortex. Functional segregation suggests that colour and motion processing should take place along different ventral occipito-temporal and lateral occipito-parietal pathways, respectively. Hence, a different topographical distribution might be expected for the motion-onset VEPs elicited by chromatic and luminance motion stimuli. We recorded motion-onset VEPs to moving luminance or isoluminant chromatic sinusoidal grating stimuli from five electrodes sites located at Oz, and at four locations (T1-T4) lateral to Oz, at intervals of 5% of the head circumference. Responses were recorded from 6 subjects over a range of speeds and contrasts. The results showed that the N2 component was maximal at similar lateral electrode locations (T2) for both luminance-defined and chromatically-defined motion. The earlier P1 component was of greatest magnitude at the occipital pole (Oz) and decreased with more lateral electrode placement and again this was the same for colour and luminance responses. These similarities suggest a common origin for VEPs elicited by colour and luminance defined motion.

Keywords: Colour, motion, visual evoked potentials (VEPs).