Abstract
Representing similar stimuli and events in a distinct and non-overlapping fashion, known as pattern separation, is pivotal for normal memory function. Hippocampus and surrounding medial temporal lobe (MTL) structures, such as the perirhinal cortex, have been implicated in pattern separation. The present study tested effects of transcranial Direct Current Stimulations (tDCS) over temporal lobe on pattern separation to determine the causal role of temporal lobe structures in pattern separation, which was assessed with the Mnemonic Similarity Task (MST). In this task, participants studied a series of sequentially presented visual objects. In the subsequent recognition memory test, participants viewed a series of sequentially presented objects that could be old images from study, novel foils, or lures that were visually similar to the studied images. Participants reported whether these images were exactly the same as, similar to, or different from the studied images. Following 15-minute offline bilateral temporal lobe tDCS (both the left cathode and right anode (L-R+) and the left anode and right cathode (L+R-) configurations), participants were less likely to identify lures as ''similar'' compared to the sham condition, indicating an impairment in pattern separation resulting from temporal lobe tDCS. In contrast, no significant difference in overall accuracy was found for participants' discrimination of old and new images. Together, these results show that temporal lobe tDCS specifically modulates pattern separation function without changing participants' baseline recognition memory performance, suggesting a causal role of temporal lobe structures in pattern separation.
Meeting abstract presented at VSS 2016