Poster Session E, Monday, March 25, 2:30 – 4:30 pm, Pacific Concourse
Differential parietal activations following remapping in a visuospatial memory task
Jordan Pierce1, Arnaud Saj2, Patrik Vuilleumier1; 1University of Geneva, 2University Hospitals of Geneva
Remapping is a process that updates visual information in internal spatial representations across eye movements, allowing for stable perception of the environment. Previous work has demonstrated visual remapping activity in parietal cortex during saccades. Here, we used functional MRI to investigate spatial remapping during two visuospatial memory tasks requiring either overt (accompanied by a saccade) or covert (with central fixation) attention shifts to peripheral distracters. Participants had to remember the position and color of a lateralized dot during a saccade or attention shift, requiring them to update the dot position in memory, and then indicated if a second dot matched the first. Behavioral results indicated that participants generally could answer correctly regardless of where the dots or distracting stimulus appeared. Crucially, however, fMRI data revealed differential activation patterns within parietal cortex as a function of the different visual, motor, and interhemispheric remapping demands in the saccade task, presumably mediating the maintenance of spatial position in perceptual and motor maps. We also observed stronger right parietal activation for left vs. right saccade trials that could reflect a right hemisphere dominance in spatial processing. No differential activation related to remapping was found during the covert attention shift task, indicating that this condition did not necessitate the same remapping processes as the saccade condition. Overall these results further elucidate the mechanisms of spatial remapping in human posterior parietal cortex and their importance to attention processing and ocular motor behavior, with potential implications for understanding visuospatial attention deficits in hemispatial neglect.
Topic Area: PERCEPTION & ACTION: Vision