Neural correlates of memory in an immersive spatiotemporal context

We investigated memory encoding and retrieval during a quasi-naturalistic spatial-episodic memory task in which subjects delivered items to landmarks in a virtual environment and later recalled the delivered items. Recall transitions revealed spatial and temporal organization of studied items. Using scalp electroencephalography (EEG), we asked whether neural signatures of successful encoding and retrieval uncovered in traditional word list tasks also appear when learning occurs within a spatiotemporal context. We found that increased theta (T +) and decreased alpha/beta (A−) accompanied successful encoding events, with the addition of increased gamma (G+) for retrieval events. Logistic-regression classifiers trained on these spectral features reliably predicted encoding and retrieval success in hold-out sessions. Both univariate and multivariate analyses of EEG data revealed a similar spectral T +A−G+ of successful encoding and retrieval. These findings extend behavioral and neural signatures of recall to naturalistic and multidimensional encoding conditions.