Persistent neural activity in the prefrontal cortex (PFC) has been implicated as the neural mechanism by which primates maintain information in working memory (WM) that is no longer readily observable in the environment but necessary for a subsequent behavioral response. During human neuroimaging experiments, this persistent activity has been routinely observed in the precentral sulcus (PCS), the putative homologue of the monkey frontal eye fields. The PCS has also recently been shown to contain a retinotopic map of space. Here, we combined computational neuroimaging and repetitive transcranial magnetic stimulation (rTMS) during a classic spatial WM task to test the assumption that this persistent neural activity observed in the PCS is responsible for WM maintenance. First, we used population receptive field mapping to identify our stimulation site in individual subjects. This method allows for a much more accurate localization of the retinotopic map in the PCS. We then measured subject performance on a memory-guided saccade task where a short burst of rTMS was applied during the task delay period. During this period the location is no longer visible but must be maintained in WM. Stimulation of the PCS caused slower response times and an increase in error in the contralateral visual field. Moreover, we used computational modeling to better describe the spatial distribution of systematic error caused by the perturbation. These results provide critical insights into the function of persistent neural activity in PFC, as well as the underlying coordinate system that spatial locations are coded in within the PCS.
Saturday, April 2nd, Data Blitz Session 2: 2:30-3:45 PM, Sutton South
Tuesday, April 5th, Poster Session F: 8:00-10:00 AM, Americas Hall I, Poster F67