Alpha rhythms reveal when and where item and associative memories are retrieved

Martín-Buro, M. C., Wimber, M. , Henson, R. N. and Staresina, B. P. (2020) Alpha rhythms reveal when and where item and associative memories are retrieved. Journal of Neuroscience, 40(12), pp. 2510-2518. (doi: 10.1523/JNEUROSCI.1982-19.2020) (PMID:32034067) (PMCID:PMC7083536)

Abstract

Memories for past experiences can range from vague recognition to full-blown recall of associated details. Electroencephalography has shown that recall signals unfold a few hundred milliseconds after simple recognition, but has only provided limited insights into the underlying brain networks. Functional magnetic resonance imaging (fMRI) has revealed a “core recollection network” (CRN) centered on posterior parietal and medial temporal lobe regions, but the temporal dynamics of these regions during retrieval remain largely unknown. Here we used Magnetoencephalography in a memory paradigm assessing correct rejection (CR) of lures, item recognition (IR) and associative recall (AR) in human participants of both sexes. We found that power decreases in the alpha frequency band (10–12 Hz) systematically track different mnemonic outcomes in both time and space: Over left posterior sensors, alpha power decreased in a stepwise fashion from 500 ms onward, first from CR to IR and then from IR to AR. When projecting alpha power into source space, the CRN known from fMRI studies emerged, including posterior parietal cortex (PPC) and hippocampus. While PPC showed a monotonic change across conditions, hippocampal effects were specific to recall. These region-specific effects were corroborated by a separate fMRI dataset. Importantly, alpha power time courses revealed a temporal dissociation between item and associative memory in hippocampus and PPC, with earlier AR effects in hippocampus. Our data thus link engagement of the CRN to the temporal dynamics of episodic memory and highlight the role of alpha rhythms in revealing when and where different types of memories are retrieved.

• Item Type: Articles
• Additional Information: This work was supported by a Wellcome Trust/Royal Society Sir Henry Dale Fellowship (107672/Z/15/Z) and an MRC CBU intramural project grant to B.P.S. M.C.M.-B. received funding from Boehringer Ingelheim Fonds.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Wimber, Professor Maria
• Authors: Martín-Buro, M. C., Wimber, M., Henson, R. N., and Staresina, B. P.
• College/School: College of Medical Veterinary and Life Sciences > School of Psychology & Neuroscience
• Journal Name: Journal of Neuroscience
• Publisher: Society for Neuroscience
• ISSN: 0270-6474
• ISSN (Online): 1529-2401
• Published Online: 07 February 2020
• Copyright Holders: Copyright © 2020 Martín-Buro et al.
• First Published: First published in Journal of Neuroscience 40(12): 2510-2518
• Publisher Policy: Reproduced under a Creative Commons License