Elsevier

NeuroImage

Volume 219, 1 October 2020, 117030
NeuroImage

Neural pattern similarity across concept exemplars predicts memory after a long delay

https://doi.org/10.1016/j.neuroimage.2020.117030Get rights and content
Under a Creative Commons license
open access

Highlights

  • Neural similarity during encoding predicts subsequent memory of novel concepts.

  • Encoding similarity is robust across different exemplars.

  • Pattern similarity predicts memory after one month.

Abstract

The irregularities of the world ensure that each interaction we have with a concept is unique. In order to generalize across these unique encounters to form a high-level representation of a concept, we must draw on similarities between exemplars to form new conceptual knowledge that is maintained over a long time. Two neural similarity measures — pattern robustness and encoding-retrieval similarity — are particularly important for predicting memory outcomes. In this study, we used fMRI to measure activity patterns while people encoded and retrieved novel pairings between unfamiliar (Dutch) words and visually presented animal species. We address two underexplored questions: 1) whether neural similarity measures can predict memory outcomes, despite perceptual variability between presentations of a concept and 2) if pattern similarity measures can predict subsequent memory over a long delay (i.e., one month). Our findings indicate that pattern robustness during encoding in brain regions that include parietal and medial temporal areas is an important predictor of subsequent memory. In addition, we found significant encoding-retrieval similarity in the left ventrolateral prefrontal cortex after a month’s delay. These findings demonstrate that pattern similarity is an important predictor of memory for novel word-animal pairings even when the concept includes multiple exemplars. Importantly, we show that established predictive relationships between pattern similarity and subsequent memory do not require visually identical stimuli (i.e., are not simply due to low-level visual overlap between stimulus presentations) and are maintained over a month.

Keywords

Episodic
Semantic
Memory
Pattern similarity
Encoding
Retrieval

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