Poster B101, Sunday, March 26, 8:00 – 10:00 am, Pacific Concourse
Visual sampling predicts hippocampal activity
Zhong-Xu Liu1, Kelly Shen1, Rosanna K. Olsen1,2, Jennifer D. Ryan1,2; 1Rotman Research Institute at Baycrest Health Sciences, Toronto, 2University of Toronto
Eye movements serve to accumulate information from the visual world, contributing to the formation of coherent memory representations that support cognition and behaviour. The hippocampus and the oculomotor network are well connected anatomically through an extensive set of polysynaptic pathways. However, the extent to which visual sampling behaviour is related to functional responses in the hippocampus during encoding has not been directly studied in human neuroimaging. In the current study, participants engaged in a face processing task while brain responses were recorded with functional magnetic resonance imaging (fMRI) and eye movements were simultaneously monitored. The number of gaze fixations that a participant made on a given trial was significantly correlated with hippocampal activation, such that more fixations were associated with stronger hippocampal activation. Similar results were also found in the fusiform face area, a face-selective perceptual processing region. Notably, the number of fixations was associated with stronger hippocampal activation when the presented faces were novel, but not when the faces were repeated. Increases in fixations during viewing of novel faces also led to larger repetition-related suppression in the hippocampus, indicating that this fixation-hippocampal relationship may reflect the ongoing development of lasting representations. Taken together, these results provide novel empirical support for the idea that visual exploration and hippocampal binding processes are inherently linked.
Topic Area: LONG-TERM MEMORY: Episodic