RT Journal Article
SR Electronic
T1 The hippocampus as the switchboard between perception and memory
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2020.05.20.104539
DO 10.1101/2020.05.20.104539
A1 Matthias S. Treder
A1 Ian Charest
A1 Sebastian Michelmann
A1 María Carmen Martín-Buro
A1 Frédéric Roux
A1 Fernando Carceller-Benito
A1 Arturo Ugalde-Canitrot
A1 David T. Rollings
A1 Vijay Sawlani
A1 Ramesh Chelvarajah
A1 Maria Wimber
A1 Simon Hanslmayr
A1 Bernhard P. Staresina
YR 2021
UL http://biorxiv.org/content/early/2021/04/06/2020.05.20.104539.abstract
AB Adaptive memory recall requires a rapid and flexible switch from external perceptual reminders to internal mnemonic representations. However, owing to the limited temporal or spatial resolution of brain imaging modalities used in isolation, the hippocampal-cortical dynamics supporting this process remain unknown. We thus employed an object-scene cued recall paradigm across two studies, including intracranial Electroencephalography (iEEG) and high-density scalp EEG. First, a sustained increase in hippocampal high gamma power (60-110 Hz) emerged 500 ms after cue onset and distinguished successful vs. unsuccessful recall. This increase in gamma power for successful recall was followed by a decrease in hippocampal alpha power (8-12 Hz). Intriguingly, the hippocampal gamma power increase marked the moment at which extrahippocampal activation patterns shifted from perceptual cue towards mnemonic target representations. In parallel, source-localised EEG alpha power revealed that the recall signal progresses from hippocampus to posterior parietal cortex and then to medial prefrontal cortex. Together, these results identify the hippocampus as the switchboard between perception and memory and elucidate the ensuing hippocampal-cortical dynamics supporting the recall process.Significance How do we adaptively switch from perceiving the external world to retrieving goal-relevant internal memories? To tackle this question, we used – in a cued-recall paradigm - direct intracranial recordings from the human hippocampus complemented by high-density scalp Electroencephalography (EEG). We found that a hippocampal signal ~500 ms after a perceptual cue marks the conversion from external (perceptual) to internal (mnemonic) representations. This sets in motion a recall cascade involving posterior parietal and medial prefrontal cortex, revealed via source-localised and time-resolved EEG alpha power. Together, these results unveil the hippocampal-cortical dynamics supporting rapid and flexible memory recall.Competing Interest StatementThe authors have declared no competing interest.