Differential cortical activation during voluntary and reflexive saccades in man

Mort, Dominic J. and Perry, Richard J. and Mannan, Sabira K. and Hodgson, Timothy L. and Anderson, Elaine and Quest, Rebecca and McRobbie, Donald and McBride, Alan and Husain, Masud and Kennard, Christopher (2003) Differential cortical activation during voluntary and reflexive saccades in man. NeuroImage, 18 (2). pp. 231-246. ISSN 1053-8119

Full content URL: http://dx.doi.org/10.1016/S1053-8119(02)00028-9

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Item Type:Article
Item Status:Live Archive

Abstract

A saccade involves both a step in eye position and an obligatory shift in spatial attention. The traditional division of saccades into two types, the "reflexive" saccade made in response to an exogenous stimulus change in the visual periphery and the "voluntary" saccade based on an endogenous judgement to move gaze, is supported by lines of evidence which include the longer onset latency of the latter and the differential effects of lesions in humans and primates on each. It has been supposed that differences between the two types of saccade derive from differences in how the spatial attention shifts involved in each are processed. However, while functional imaging studies have affirmed the close link between saccades and attentional shifts by showing they activate overlapping cortical networks, attempts to contrast exogenous with endogenous ("covert") attentional shifts directly have not revealed separate patterns of cortical activation. We took the "overt" approach, contrasting whole reflexive and voluntary saccades using event-related fMRI. This demonstrated that, relative to reflexive saccades, voluntary saccades produced greater activation within the frontal eye fields and the saccade-related area of the intraparietal sulci. The reverse contrast showed reflexive saccades to be associated with relative activation of the angular gyrus of the inferior parietal lobule, strongest in the right hemisphere. The frequent involvement of the right inferior parietal lobule in lesions causing hemispatial neglect has long implicated this parietal region in an important, though as yet uncertain, role in the awareness and exploration of space. This is the first study to demonstrate preferential activation of an area in its posterior part, the right angular gyrus, during production of exogenously triggered rather than endogenously generated saccades, a finding which we propose is consistent with an important role for the angular gyrus in exogenous saccadic orienting. © 2003 Elsevier Science (USA). All rights reserved.

Keywords:adult, article, attention, brain cortex, controlled study, event related potential, eye position, female, human, human cell, human tissue, latent period, nuclear magnetic resonance imaging, onset age, parietal lobe, primate, priority journal, saccadic eye movement, stimulus response, Adult, Arousal, Brain Mapping, Cerebral Cortex, Dominance, Cerebral, Humans, Image Processing, Computer-Assisted, Imaging, Three-Dimensional, Magnetic Resonance Imaging, Male, Nerve Net, Orientation, Oxygen Consumption, Pattern Recognition, Visual, Reflex, Saccades, Visual Fields
Subjects:C Biological Sciences > C800 Psychology
Divisions:College of Social Science > School of Psychology
ID Code:10542
Deposited On:09 Jul 2013 16:20

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