Lesser neural pattern similarity across repeated tests is associated with better long-term memory retention
2015 (English)In: Journal of Neuroscience, ISSN 0270-6474, E-ISSN 1529-2401, Vol. 35, no 26, 9595-9602 p.Article in journal (Refereed) Published
Encoding and retrieval processes enhance long-termmemoryperformance. The efficiency of encoding processes has recently been linkedto representational consistency: the reactivation of a representation that gets more specific each time an item is further studied. Here weexamined the complementary hypothesis of whether the efficiency of retrieval processes also is linked to representational consistency.Alternatively, recurrent retrieval might foster representational variability—the altering or adding of underlying memory representations.Human participants studied 60 Swahili–Swedish word pairs before being scanned with fMRI the same day and 1 week later. On Day1, participants were tested three times on each word pair, and on Day 7 each pair was tested once. A BOLD signal change in right superiorparietal cortex was associated with subsequent memory on Day 1 and with successful long-term retention on Day 7. A representationalsimilarity analysis in this parietal region revealed that beneficial recurrent retrieval was associated with representational variability, suchthat the pattern similarity on Day 1 was lower for retrieved words subsequently remembered compared with those subsequently forgotten.This was mirrored by a monotonically decreased BOLD signal change in dorsolateral prefrontal cortex on Day 1 as a function ofrepeated successful retrieval for words subsequently remembered, but not for words subsequently forgotten. This reduction in prefrontalresponse could reflect reduced demands on cognitive control. Collectively, the results offer novel insights into why memory retentionbenefits from repeated retrieval, and they suggest fundamental differences between repeated study and repeated testing.
Place, publisher, year, edition, pages
Society for Neuroscience , 2015. Vol. 35, no 26, 9595-9602 p.
fMRI; memory; pattern similarity; repeated testing; retrieval; RSA
IdentifiersURN: urn:nbn:se:umu:diva-96392DOI: 10.1523/JNEUROSCI.3550-14.2015ISI: 000358252600007OAI: oai:DiVA.org:umu-96392DiVA: diva2:764445