Parietal stimulation destabilizes spatial updating across saccadic eye movements

Morris, A. P., Chambers, C. D. and Mattingley, J. B. (2007) Parietal stimulation destabilizes spatial updating across saccadic eye movements. Proceedings of the National Academy of Sciences, 104 21: 9069-9074. doi:10.1073/pnas.0610508104

Author Morris, A. P.
Chambers, C. D.
Mattingley, J. B.
Title Parietal stimulation destabilizes spatial updating across saccadic eye movements
Journal name Proceedings of the National Academy of Sciences   Check publisher's open access policy
ISSN 0027-8424
Publication date 2007
Year available 2007
Sub-type Article (original research)
DOI 10.1073/pnas.0610508104
Open Access Status Not Open Access
Volume 104
Issue 21
Start page 9069
End page 9074
Total pages 6
Editor N. R. Cozzarelli
Place of publication Washington, DC, United States of America
Publisher National Academy of Sciences
Collection year 2008
Language eng
Subject C1
380101 Sensory Processes, Perception and Performance
780108 Behavioural and cognitive sciences
Abstract Saccadic eye movements cause sudden and global shifts in the retinal image. Rather than causing confusion, however, eye movements expand our sense of space and detail. In macaques, a stable representation of space is embodied by neural populations in intraparietal cortex that redistribute activity with each saccade to compensate for eye displacement, but little is known about equivalent updating mechanisms in humans. We combined noninvasive cortical stimulation with a double-step saccade task to examine the contribution of two human intraparietal areas to transsaccadic spatial updating. Right hemisphere stimulation over the posterior termination of the intraparietal sulcus (IPSp) broadened and shifted the distribution of second-saccade endpoints, but only when the first-saccade was directed into the contralateral hemifield. By interleaving trials with and without cortical stimulation, we show that the shift in endpoints was caused by an enduring effect of stimulation on neural functioning (e.g., modulation of neuronal gain). By varying the onset time of stimulation, we show that the representation of space in IPSp is updated immediately after the first-saccade. In contrast, stimulation of an adjacent IPS site had no such effects on second-saccades. These experiments suggest that stimulation of IPSp distorts an eye position or displacement signal that updates the representation of space at the completion of a saccade. Such sensory-motor integration in IPSp is crucial for the ongoing control of action, and may contribute to visual stability across saccades.
Keyword Coordinate transformations
Parietal cortex
Spatial representation
Transcranial magnetic stimulation
Q-Index Code C1

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Created: Mon, 18 Feb 2008, 17:21:00 EST