Michael E. Hasselmo, Patrick A. LaChance, Jennifer C. Robinson, Samantha L. Malmberg, Mahir Patel, Elaina Gross, Danielle E. Everett, Shruthi Sankaranarayanan, Jiarui Fang. How does the response of egocentric boundary cells depend upon the coordinate system of environmental features? bioRxiv 2025.02.03.636060; doi: https://doi.org/10.1101/2025.02.03.636060

ABSTRACT
“Neurons in the retrosplenial (RSC) (Alexander et al., 2020a; LaChance and Hasselmo, 2024) and postrhinal cortex (POR) respond to environmental boundaries and configurations in egocentric coordinates relative to an animals current position. Neurons in these structures and adjacent structures also respond to spatial dimensions of self- motion such as running velocity (Carstensen et al., 2021; Robinson et al., 2024). Data and modeling suggest that these responses could be essential for guiding behaviors such as barrier avoidance and goal finding (Erdem and Hasselmo, 2012; 2014). However, these findings still leave the unanswered question: What are the features and what are the coordinate systems of these features that drive these egocentric neural responses? Here we present models of the potential circuit mechanisms generating egocentric responses in RSC. These can be generated based on coding of internal representations of barriers in head-centered coordinates of distance and angle that are transformed based on current running velocity for trajectory planning and obstacle avoidance. This hypothesis is compared with an alternate potentially complementary hypothesis that neurons in the same regions might respond to retinotopic position of features at the top, bottom or edges of walls as a precursor to head-centered coordinates. Alternate hypotheses include the forward scanning of trajectories (ray tracing) to test for collision with barriers, or the comparison of optic flow on different sides of the animal. These hypotheses generate complementary modeling predictions about how changes in environmental parameters could alter the neural responses of egocentric boundary cells that are presented here.”

Michael E. Hasselmo, Patrick A. LaChance, Jennifer C. Robinson, Samantha L. Malmberg, Mahir Patel, Elaina Gross, Danielle E. Everett, Shruthi Sankaranarayanan, Jiarui Fang. How does the response of egocentric boundary cells depend upon the coordinate system of environmental features? bioRxiv 2025.02.03.636060; doi: https://doi.org/10.1101/2025.02.03.636060