Jacob Bellmund | Entorhinal maps for human memory

The hippocampal-entorhinal region supports spatial navigation and episodic memory, putatively through the mapping of cognitive spaces. In this talk, I will argue for the idea that coding principles discovered in spatial navigation research are shared across cognitive domains. For example, the regular firing patterns of grid cells in the entorhinal cortex supposedly provide a metric for cognitive maps. Hence, grid pattern distortions might affect cognitive functions. Employing highly immersive virtual reality technology, I demonstrate that — mirroring distortions of grid-cell firing patterns in navigating rodents — human spatial memory is distorted in a trapezoidal environment. These mnemonic distortions, which persist outside of the trapezoidal environment, are captured by a model grid system based on the successor representation. Beyond space, time is considered a second fundamental dimension for episodic memories. Using representational similarity analysis (RSA) of multi-voxel patterns, I show that the anterior-lateral entorhinal cortex maps the temporal structure of a learned event sequence and that this temporal map relates to memory recall. Cognitive maps stored in memory can guide behavior through the simulation of possible future trajectories. Combining human imagination with RSA, I show that compass-like representations in the parahippocampal gyrus and grid-like hexadirectional representations in the entorhinal cortex contribute to mental simulation. Together, these data are consistent with the notion that the hippocampal-entorhinal region supports memory through the formation of cognitive maps using coding principles discovered in spatial navigation research.

Poster