The intersection between the oculomotor and hippocampal memory systems: empirical developments and clinical implications.

Jennifer D Ryan,Kelly Shen,Zhong-Xu Liu

doi:10.1111/nyas.14256

Abstract

Decades of cognitive neuroscience research has shown that where we look is intimately connected to what we remember. In this article, we review findings from human and nonhuman animals, using behavioral, neuropsychological, neuroimaging, and computational modeling methods, to show that the oculomotor and hippocampal memory systems interact in a reciprocal manner, on a moment‐to‐moment basis, mediated by a vast structural and functional network. Visual exploration serves to efficiently gather information from the environment for the purpose of creating new memories, updating existing memories, and reconstructing the rich, vivid details from memory. Conversely, memory increases the efficiency of visual exploration. We call for models of oculomotor control to consider the influence of the hippocampal memory system on the cognitive control of eye movements, and for models of hippocampal and broader medial temporal lobe function to consider the influence of the oculomotor system on the development and expression of memory. We describe eye movement–based applications for the detection of neurodegeneration and delivery of therapeutic interventions for mental health disorders for which the hippocampus is implicated and memory dysfunctions are at the forefront.

Highlights

The idea that memory can be revealed through the movements of the eyes is not intuitive
How could a memory signal drive oculomotor behavior, if not at least partly via information represented in regions of the brain critical for memory, the hippocampus and/or the extended MTL?27 Here, we focus on the contribution of representations dependent on the hippocampus and the broader MTL regarding items, such as the arrangement of features within an item, temporal sequences, and the relative spatial positions of items within a broader environment, on ongoing visual exploration and, on the emerging role of visual exploration in the development of lasting memory representations supported by the hippocampus and MTL
Greater sampling behavior during initial viewing was associated with larger reductions in hippocampal activity across subsequent viewings. Such repetition-related decreases in neural activity have been taken as a proxy for memory formation; visual exploration was related to the development of lasting representations.[96]. These findings extended prior eye-tracking research, which showed that an increase in visual exploration predicts later memory[97,98] by suggesting that the underlying mechanism for such memory benefits is an increase in hippocampal activity