We investigated memory encoding and retrieval during a hybrid spatial- episodic memory task in which subjects delivered items to landmarks in a virtual environment and later recalled the delivered items. Conditional probabilities of recall transitions revealed spatial and temporal organization of studied items. We asked whether neural signatures of successful encoding and retrieval uncovered in traditional word-list paradigms also appear when learning occurs within a spatiotemporal context under conditions that interpose a navigation task between each item encoding event. 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.

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