Maintenance of Visual Stability in the Human Posterior Parietal Cortex

Authors

Erik Chang, University of Western Ontario
Tony Ro, CUNY Graduate CenterFollow

Document Type

Article

Publication Date

2-1-2007

Abstract

Visual stability refers to our stable visuospatial perceptions despite the unstable visual input caused by saccades. Functional neuroimaging results, studies on patients with posterior parietal cortex (PPC) lesions, and single-unit recordings in the lateral intraparietal sulcus of primates indirectly suggest that the PPC might be a potential locus of visual stability through its involvement with spatial remapping. Here we directly explored the role of the PPC in visual stability by applying transcranial magnetic stimulation (TMS) while participants performed a perisaccadic displacement detection task. We show that TMS over the PPC but not a frontal control site alters sensitivity to displacement detection when administered just before contralateral saccades and that a general impairment in attention or in the perception of apparent motion cannot account for the decreased sensitivity. The specific relationship between the timing of TMS and saccade direction demonstrates that saccadic suppression of displacement (SSD) is likely a consequence of noisy contralateral spatial representations in the PPC around the time of a saccade. The same mechanism may keep the unstable visual world in the temporal proximity of saccades from reaching our consciousness.

Comments

This article was originally published in Journal of Cognitive Neuroscience, available at https://doi.org/10.1162/jocn.2007.19.2.266