Contributed Talk Sessions | Poster Sessions | All Posters | Search Papers

Poster Session B: Wednesday, August 13, 1:00 – 4:00 pm, de Brug & E‑Hall

Hexadirectional modulation of grid cell firing by firing rate adaptation

Guglielmo Reggio¹, Misun Kim¹, Zilong Ji¹, Daniel Bush, Caswell Barry², Neil Burgess²; ¹University College London, University of London, ²University College London

Presenter: Guglielmo Reggio

Grid cells are crucial for encoding spatial knowledge and supporting navigation. To non-invasively detect grid cell activity in humans, hexadirectional modulation (HM) methods have been developed. These methods look for macroscopic brain activity that varies with movement directions with six-fold rotational symmetry. Despite their widespread use with functional neuroimaging, the cellular origin of HM remains unclear. Here, we analysed over 1,000 grid cells recorded from freely foraging rats to evaluate two proposed mechanisms: (1) firing rate adaptation and (2) directionally tuned conjunctive grid cells. We observed significant HM after controlling for variability in speed and location using a Poisson multiplicative model. Consistent with the adaptation hypothesis, firing was reduced when grid fields were visited in close succession, a pattern more common during grid-aligned movement. These results offer a physiological explanation for HM and inform the design of future experiments aiming to detect grid cell activity non-invasively.

Topic Area: Memory, Spatial Cognition & Skill Learning

Extended Abstract: Full Text PDF