Mapping Invisible Barriers in the Human Entorhinal Cortex: Context Dependence and Previous Experience in Spatial Navigation

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

Omar Zeid¹ (ozeid3@gatech.edu), Qiliang He¹, Thackery Brown¹; ¹Georgia Institute of Technology

For years, the behavior of grid cells in rodents has been observed during spatial navigation. Recently, BOLD signals with grid-like behavior were shown in humans via fMRI. Our lab had previously shown that BOLD activity in the right Entorhinal Cortex (rEC) exhibits a grid-like representation with 6-fold symmetry relative to the angle traversed while navigating a virtual space with no barriers (“Open Field”) and a representation with 4-fold symmetry when walls were added – creating a series of corridors (“Barrier”), showing that the same neural region can represent different spaces with different strategies. We then tested whether the 4-fold signal is due to the visual perception of the walls or the conceptual knowledge that a wall cannot be traversed. To that end, we collected pilot fMRI whole-brain data using a similar experimental paradigm but with the Barrier condition replaced with one where the barriers were invisible. With both experimental conditions looking identical, the 6-fold symmetry was greatly reduced while the 4-fold symmetry increased in the Open Field condition. In addition to anatomical rEC masks like those used in the previous study, we located a functional ROI posterior to the rEC which showed a double dissociation of Open Field activity between subjects that were given the Open Field trials first compared to those that were given the Open Field trials last. It is clear from these extant results that mechanisms in these neural systems may be more context-dependent than previously hypothesized – here modulated by stimuli presentation order and neuroanatomical subdivision.

Topic Area: PERCEPTION & ACTION: Other