RT Journal Article SR Electronic T1 Persistent hippocampal neural firing and hippocampal-cortical coupling predict verbal working memory load JF Science Advances JO Sci Adv FD American Association for the Advancement of Science SP eaav3687 DO 10.1126/sciadv.aav3687 VO 5 IS 3 A1 Boran, Ece A1 Fedele, Tommaso A1 Klaver, Peter A1 Hilfiker, Peter A1 Stieglitz, Lennart A1 Grunwald, Thomas A1 Sarnthein, Johannes YR 2019 UL http://advances.sciencemag.org/content/5/3/eaav3687.abstract AB The maintenance of items in working memory relies on persistent neural activity in a widespread network of brain areas. To investigate the influence of load on working memory, we asked human subjects to maintain sets of letters in memory while we recorded single neurons and intracranial encephalography (EEG) in the medial temporal lobe and scalp EEG. Along the periods of a trial, hippocampal neural firing differentiated between success and error trials during stimulus encoding, predicted workload during memory maintenance, and predicted the subjects’ behavior during retrieval. During maintenance, neuronal firing was synchronized with intracranial hippocampal EEG. On the network level, synchronization between hippocampal and scalp EEG in the theta-alpha frequency range showed workload dependent oscillatory coupling between hippocampus and cortex. Thus, we found that persistent neural activity in the hippocampus participated in working memory processing that is specific to memory maintenance, load sensitive and synchronized to the cortex.