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The neurology of saccades and covert shifts in spatial attention: an event-related fMRI study.

Authors: R J, Perry; S, Zeki;

The neurology of saccades and covert shifts in spatial attention: an event-related fMRI study.

Abstract

Visual neglect occurs most frequently and persistently after lesions that include the right supramarginal gyrus (SMG), a part of the inferior parietal lobule. Patients with this syndrome make very few saccades to the left, and show abnormal performance on tasks in which they must covertly shift their attention to the left, suggesting that the right SMG is involved in the generation of saccades and attention shifts. Functional imaging studies of saccades and covert attention shifts in the normal brain, however, have shown weak or absent responses in both SMGs. We used event-related functional MRI to re-examine the responses to saccades and attention shifts within a single experiment, and to assess responses to left- and right-sided stimuli independently. When subjects made saccades to peripheral stimuli, the expected responses were seen in striate and prestriate cortex, the superior parietal lobules, the frontal eye fields, the supplementary motor area and the anterior insulae. In addition there was a response in the right SMG but not in the left SMG, as predicted from the clinical literature. When subjects made a covert visual assessment of the peripheral stimulus without any saccade, greater activity was seen in all of the areas in the frontoparietal network. Each area showed a bias towards contralateral stimuli, with two exceptions: the anterior insulae gave mainly ipsilateral responses, whilst the right SMG gave equal responses to right- and left-sided stimuli. These findings are discussed in the context of current theories pertaining to the clinical syndrome of neglect.

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Keywords

Adult, Male, Brain Mapping, Brain, Neural Inhibition, Middle Aged, Neuropsychological Tests, Magnetic Resonance Imaging, Functional Laterality, Oxygen, Perceptual Disorders, Cerebrovascular Circulation, Space Perception, Reaction Time, Saccades, Humans, Attention, Female, Evoked Potentials, Psychomotor Performance

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selected citations
These citations are derived from selected sources.
This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Citations provided by BIP!
popularity
This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
BIP!Popularity provided by BIP!
influence
This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Influence provided by BIP!
impulse
This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
BIP!Impulse provided by BIP!
238
Top 10%
Top 1%
Top 1%
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