The Role of Hippocampal Differentiation in Visual Object-based and Feature-based Attention

Project Summary/Abstract My career goal is to be a principal investigator at a top-ranked research institution. My scientific goal is to understand how perceptual experience is transformed into adaptive memories, and how these memories impact immediate perception. In this application, I outline an innovative research program to study how the hippocampus, a brain region typically associated with memory function, supports visual perception and attention. This research is motivated by an emerging literature suggesting that the hippocampus is involved in central aspects of vision, such as eye movements, imagery, scene perception, and visual search. However, the underlying principles that govern this contribution are debated. Recent functional magnetic resonance imaging (fMRI) studies have shown that the hippocampus distinguishes visual stimuli through a process known as differentiation. This process leads to the unexpected result that related stimuli are represented less similarly than unrelated stimuli in the hippocampus. This form of relational coding stands in stark contrast to the tuning properties of visual cortex, which represents related visual stimuli more similarly than unrelated stimuli. My research strategy uses behavioral and fMRI methods to test the novel hypothesis that hippocampal differentiation biases visual perception and behavior through the repulsion of attention away from related visual stimuli. Specifically, we test the impact of hippocampal differentiation on the repulsion of object-based attention (Specific Aim 1) and feature-based attention (Specific Aim 2). We implement proven learning protocols to measure hippocampal differentiation with high-resolution fMRI and examine how these unique neural representations relate to behavior in validated attention tasks. In Aim 1, we adapt a shape-based visual statistical learning task from the Sponsor’s lab to drive differentiation, followed by a cueing task that measures object-based attention. We predict that the degree of hippocampal differentiation between related shapes will be associated with the amount of object-based attentional repulsion. In Aim 2, we use a color-based visual associative learning task to drive hippocampal differentiation, followed by a contingent capture task that measures feature-based attention. We predict that the degree hippocampal differentiation between related colors will be associated with the amount of feature-based attentional repulsion. By linking memory systems to visual functions in the human brain, this proposed research program may reveal new sources of attentional control, with significant implications for advancing knowledge of visual deficits and for developing new approaches for visual rehabilitation.