A High-Resolution Study of Positive and Negative Retinotopic Codes in the Hippocampus

Poster Session F - Tuesday, April 16, 2024, 8:00 – 10:00 am EDT, Sheraton Hall ABC

Peter A. Angeli¹ (peter.a.angeli@dartmouth.edu), Adam Steel¹, Edward H. Silson², Caroline E. Robertson¹; ¹Dartmouth College, ²University of Edinburgh

Position-dependent activity in response to stimulation of the retina, or retinotopic coding, has long been considered a unique feature of the visual system. However, recent work has shown that higher-order cortical areas, including the default network, show retinotopic sensitivity in the form of decreasing signal during stimulation of their visual receptive field (Szinte and Knapen 2020; Klink et al., 2021). Motivated by this negative coding’s possible relevance to perception-memory interactions (Steel*, Silson* et al. 2023) and recent observations of retinotopic sensitivity in the hippocampus (Silson et al., 2021), here we characterize positive and negative retinotopic responses to visual stimuli in the hippocampus. We explored this region’s positive and negative retinotopic responses using high-resolution (7T, 1.8mm isotropic) population receptive field (pRF) mapping data from the Natural Scenes Dataset (Allen et al. 2022). On average across participants, 42% of hippocampal voxels exhibited a retinotopic response, and 43% of these voxels were negative in valence. Consistent with prior work, positive pRFs showed a significant contralateral visual field bias (i.e., left hippocampus tended to represent the right visual field) (p<0.05), while negative pRFs were more foveal. Interestingly, resting state functional connectivity analyses showed that positive and negative hippocampal pRFs co-fluctuate more strongly with congruently signed cerebral pRFs. This work suggests the importance of visual coding in structuring the interaction between the hippocampus and cerebral cortex, and adds support for the view that negative pRFs may play an important role in hippocampally-dependent cognitive processes like episodic memory and scene construction.

Topic Area: PERCEPTION & ACTION: Vision