RT Journal Article
SR Electronic
T1 Direct Brain Recordings Suggest a Causal Subsequent-Memory Effect
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2022.10.12.511606
DO 10.1101/2022.10.12.511606
A1 Daniel Y. Rubinstein
A1 Christoph T. Weidemann
A1 Michael R. Sperling
A1 Michael J. Kahana
YR 2023
UL http://biorxiv.org/content/early/2023/01/04/2022.10.12.511606.abstract
AB Endogenous variation in brain state and stimulus-specific evoked activity can both contribute to successful encoding. Previous studies, however, have not clearly distinguished among these components. We address this question by analyzing intracranial EEG recorded from epilepsy patients as they studied and subsequently recalled lists of words. We first trained classifiers to predict recall of either single items or entire lists and found that both classifiers exhibited similar performance. We found that list-level classifier output—a biomarker of successful encoding—tracked item presentation and recall events, despite having no information about the trial structure. Across widespread brain regions, decreased low- and increased high-frequency activity (HFA) marked successful encoding of both items and lists. We found regional differences in the hippocampus and prefrontal cortex, where in the hippocampus HFA correlated more strongly with item recall, whereas in the prefrontal cortex HFA correlated more strongly with list performance. Despite subtle differences in item- and list-level features, the similarity in overall classification performance, spectral signatures of successful recall, and fluctuations of spectral activity across the encoding period argue for a shared endogenous process that causally impacts the brain’s ability to learn new information.Competing Interest StatementThe authors have declared no competing interest.