Hexadirectional modulation of EEG gamma band activity
The medial temporal lobe (MTL) houses specialised cell types supporting spatial representation in the human brain. Among these are grid cells that encode the location of the navigator, displaying a geometrically structured anchoring to the environment. While macroscopic grid-cell-like coding in humans is typically investigated using functional magnetic resonance imaging or invasive electrophysiological methods in clinical populations, we demonstrate the feasibility of using non-invasive scalp electroencephalography (EEG) to capture the characteristic six-fold modulation of high-frequency activity source-localised to the MTL. We found hexadirectional modulations of the low- and high-gamma band activity by movement direction in virtual reality. Furthermore, individual preference to use an allocentric reference frame was linked to higher hexadirectional modulation in the low gamma band and encoding a location along the putative grid axes of high gamma band predicted faster retrieval of the remembered location. The use of scalp EEG to capture grid-cell-like activity and its functional relevance sets the foundation for investigating the MTL activity in richer experimental contexts.