Retrieval aids the creation of a generalised memory trace and strengthens episode-unique information

Ferreira, C.S., Charest, I. and Wimber, M. (2019) Retrieval aids the creation of a generalised memory trace and strengthens episode-unique information. NeuroImage, 201, 115996. (doi: 10.1016/j.neuroimage.2019.07.009) (PMID:31280012)

Abstract

Generalised knowledge can adaptively guide our behaviour and help us navigate the world. In this study, we aim to test the role of memory retrieval in promoting such generalisation of memories. Retrieval is known to be a powerful memory enhancer. Both cognitive and neurobiological theories of retrieval-mediated learning propose that this benefit is due to the co-activation of related (semantic) information during retrieval, which strengthens this co-activated associative network. By doing so, retrieval might play an important role in the generalisation of the memory trace. Here, we used univariate and pattern fMRI analyses to investigate whether memory representations that undergo retrieval (vs. restudy) become generalised over time. Participants encoded scene-object pairs and either retrieved or restudied the objects over two sessions, two days apart. We analysed univariate and multivariate changes in brain activity specific to retrieval but not restudy, and tested whether predicted changes occur rapidly within a session, or evolve slowly, across the two days. Consistent with a role of retrieval in the semanticisation of memories, univariate analyses showed an increase in medial prefrontal cortex (mPFC) activation across consecutive retrieval attempts, and a multivariate increase in similarity between categorically related information. In addition to this semanticisation, we also observed that retrieval strengthened the patterns unique to the original study episodes. Semantic-categorical and episode-unique strengthening both evolved slowly, across two days, and were most pronounced in parietal areas. Our findings corroborate the hypothesis that retrieval supports the creation of a generalised memory trace, and show that this strengthening does not come at the expense of episode-unique information. Active remembering thus seems to promote a stable and adaptive memory that can be flexibly used to access both contextually specific and more abstract generalised information.

• Item Type: Articles
• Additional Information: This work was supported by grant ES/M001644/1, from the Economic and Social Research Council UK, awarded to M.W. and by the British Academy Postdoctoral Fellowship PF2∖180009, awarded to C.S.F.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Wimber, Professor Maria and Charest, Mr Ian
• Authors: Ferreira, C.S., Charest, I., and Wimber, M.
• College/School: College of Medical Veterinary and Life Sciences > School of Psychology & Neuroscience; College of Science and Engineering > School of Psychology
• Journal Name: NeuroImage
• Publisher: Elsevier
• ISSN: 1053-8119
• ISSN (Online): 1095-9572
• Published Online: 04 July 2019
• Copyright Holders: Copyright © 2019 Elsevier Inc.
• First Published: First published in Neuroimage 201: 115996
• Publisher Policy: Reproduced in accordance with the publisher copyright policy