Encoding and retrieval of virtual naturalistic experiences during OPM-MEG

Poster Session C - Sunday, April 14, 2024, 5:00 – 7:00 pm EDT, Sheraton Hall ABC

Robert Seymour¹ (rob.seymour@ucl.ac.uk), Nicholas Alexander¹, Yan Wu¹, George O'Neill¹, Stephanie Mellor¹, Ryan Timms¹, Tim Tierney¹, Gareth Barnes¹, Eleanor Maguire¹; ¹University College London

Our life experiences are captured in autobiographical memories. To date, neuroimaging research has predominantly focussed on the recall of autobiographical memories, because examining their formation is challenging in head-immobilising brain scanners like MRI and cryogenic magnetoencephalography (MEG). Here we circumvented this issue by utilising whole-head, wearable optically pumped magnetometer (OPM)-MEG combined with interactive virtual reality. Healthy adult human participants moved through a virtual town using a walk-in-place method. During their town tour they had a range of naturalistic experiences that varied in content and duration. We collected neural data throughout the tour using a ~130 channel OPM-MEG system. The next day, and also during OPM-MEG, participants recalled and described their memories of the tour experiences. Our analysis focussed on characterising the neural signatures, across frequency bands, associated with forming memories of these virtual naturalistic experiences, including those that went on to be remembered or degraded (where now the ground truth is known). This rich dataset has yielded several notable findings, which include: (1) During encoding, increased gamma power (35-60 Hz) localised to retrosplenial cortex and hippocampus was especially prominent at the beginning and end of experiences, potentially aligning with ideas about event boundaries. (2) Retrieval of virtual experiences engaged the same set of brain regions previously implicated in recalling actual lived experiences. More generally, our study shows that it is possible to combine virtual reality and OPM-MEG to examine how the brain functions in something much more akin to everyday life which, until now, has eluded detailed scrutiny.

Topic Area: LONG-TERM MEMORY: Episodic