Directional coupling of slow and fast hippocampal gamma with neocortical alpha/beta oscillations in human episodic memory

Griffiths, B. J. et al. (2019) Directional coupling of slow and fast hippocampal gamma with neocortical alpha/beta oscillations in human episodic memory. Proceedings of the National Academy of Sciences of the United States of America, 116(43), pp. 21834-21842. (doi: 10.1073/pnas.1914180116) (PMID:31597741) (PMCID:PMC6815125)

Abstract

Episodic memories hinge upon our ability to process a wide range of multisensory information and bind this information into a coherent, memorable representation. On a neural level, these 2 processes are thought to be supported by neocortical alpha/beta desynchronization and hippocampal theta/gamma synchronization, respectively. Intuitively, these 2 processes should couple to successfully create and retrieve episodic memories, yet this hypothesis has not been tested empirically. We address this by analyzing human intracranial electroencephalogram data recorded during 2 associative memory tasks. We find that neocortical alpha/beta (8 to 20 Hz) power decreases reliably precede and predict hippocampal “fast” gamma (60 to 80 Hz) power increases during episodic memory formation; during episodic memory retrieval, however, hippocampal “slow” gamma (40 to 50 Hz) power increases reliably precede and predict later neocortical alpha/beta power decreases. We speculate that this coupling reflects the flow of information from the neocortex to the hippocampus during memory formation, and hippocampal pattern completion inducing information reinstatement in the neocortex during memory retrieval.

• Item Type: Articles
• Additional Information: This research was supported by grants from the European Research Council (https://erc.europa.eu/, Consolidator Grant 647954; to S.H.); Wolfson Foundation and Royal Society (https://royalsociety. org/grants-schemes-awards/grants/wolfson-researchmerit/; to S.H.); The Economic Social Sciences Research Council (https://esrc.ukri.org/, ES/R010072/1; to S.H.); Well- come Trust/Royal Society Sir Henry Dale Fellowship (107672/Z/15/Z; to B.S.); and European Research Council Starting Grant (ERC-STG-2016-715714; to M.W.).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Hanslmayr, Professor Simon and Wimber, Professor Maria
• Authors: Griffiths, B. J., Parish, G., Roux, F., Michelmann, S., van der Plas, M., Kolibius, L. D., Chelvarajah, R., Rollings, D. T., Sawlani, V., Hamer, H., Gollwitzer, S., Kreiselmeyer, G., Staresina, B., Wimber, M., and Hanslmayr, S.
• College/School: College of Medical Veterinary and Life Sciences > School of Psychology & Neuroscience
• Journal Name: Proceedings of the National Academy of Sciences of the United States of America
• Publisher: National Academy of Sciences
• ISSN: 0027-8424
• ISSN (Online): 1091-6490
• Published Online: 09 October 2019
• Copyright Holders: Copyright © 2019 The Authors
• First Published: First published in Proceedings of the National Academy of Sciences of the United States of America 116(43): 21834-21842
• Publisher Policy: Reproduced under a Creative Commons Licence