Poster F41, Tuesday, March 27, 8:00-10:00 am, Exhibit Hall C
Can TMS to Visual Cortex Reactivate Activity-Silent Representations in Visual Working Memory?
Morgan Widhalm1, Nathan Rose1; 1University of Notre Dame
Recent research on working memory (WM) has shown evidence for activity-silent retention mechanisms and the reactivation of latent representations in WM with TMS on simultaneously-recorded EEG (Rose et al., 2016, Science). What is unclear is if activity-silent representations are maintained in sensory cortex and, thus, if TMS could reactivate stimulus-specific features of latent representations. Here we applied single pulse TMS to left primary visual cortex to first localize phosphenes in the right visual field for each participant. Then two oriented gratings were presented -- one at the phosphene location and the other in the opposite (left) hemifield at the same angle and distance from fixation. These gratings were to be retained on a WM task with two retro-cues and two recognition probes. During the delay period, single pulse TMS was applied to left primary visual cortex to induce phosphenes in the contralateral visual field. TMS was applied at 100% or 80% of phosphene threshold to see if it would differentially reactivate or perturb memory of the orientation of the items presented ipsilateral and contralateral to stimulation. Memory precision was only impaired when TMS was applied at 100% of phosphene threshold prior to the second probe. There was no difference in precision for the orientation presented either contralateral to TMS (at the phosphene location) or ipsilateral to TMS. Ongoing analysis of the TMS-evoked response on simultaneously recorded EEG with inverted encoding models will reveal if TMS can reconstruct the specific orientation of the latent memory item.
Topic Area: EXECUTIVE PROCESSES: Working memory