Parietal stimulation destabilises spatial updating across saccadic eye movements.
Proceedings of the National Academy of Sciences of the United States of America
9069 - 9074.
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 non-invasive cortical stimulation with a double-step saccade task to examine the contribution of two human intraparietal areas to trans-saccadic 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.
|Title:||Parietal stimulation destabilises spatial updating across saccadic eye movements|
|Additional information:||Imported via OAI, 7:29:01 11th Sep 2007|
|UCL classification:||UCL > School of Life and Medical Sciences > Faculty of Life Sciences|
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