Not-so-working memory: Drift in functional magnetic resonance imaging pattern representations during maintenance predicts errors in a visual working memory task

Phui Cheng Lim, Emily J. Ward, Timothy J. Vickery, Matthew R. Johnson

Research output: Contribution to journalArticle

Abstract

Working memory (WM) is critical to many aspects of cognition, but it frequently fails. Much WM research has focused on capacity limits, but even for single, simple features, the fidelity of individual representations is limited. Why is this? One possibility is that, because of neural noise and interference, neural representations do not remain stable across a WM delay, nor do they simply decay, but instead, they may “drift” over time to a new, less accurate state. We tested this hypothesis in a functional magnetic resonance imaging study of a match/nonmatch WM recognition task for a single item with a single critical feature: Orientation. We developed a novel pattern-based index of “representational drift” to characterize ongoing changes in brain activity patterns throughout the WM maintenance period, and we were successfully able to predict performance on the match/nonmatch recognition task using this representational drift index. Specifically, in trials where the target and probe stimuli matched, participants incorrectly reported more nonmatches when their activity patterns drifted away from the target. In trials where the target and probe did not match, participants incorrectly reported more matches when their activity patterns drifted toward the probe. On the basis of these results, we contend that neural noise does not cause WM errors merely by degrading representations and increasing random guessing; instead, one means by which noise introduces errors is by pushing WM representations away from the target and toward other meaningful (yet incorrect) configurations. Thus, we demonstrate that behaviorally meaningful drift within representation space can be indexed by neuroimaging.

Original languageEnglish (US)
Pages (from-to)1520-1534
Number of pages15
JournalJournal of Cognitive Neuroscience
Volume31
Issue number10
DOIs
StatePublished - Jan 1 2019

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Short-Term Memory
Maintenance
Magnetic Resonance Imaging
Noise
Neuroimaging
Cognition
Brain
Research

ASJC Scopus subject areas

  • Cognitive Neuroscience

Cite this

Not-so-working memory : Drift in functional magnetic resonance imaging pattern representations during maintenance predicts errors in a visual working memory task. / Lim, Phui Cheng; Ward, Emily J.; Vickery, Timothy J.; Johnson, Matthew R.

In: Journal of Cognitive Neuroscience, Vol. 31, No. 10, 01.01.2019, p. 1520-1534.

Research output: Contribution to journalArticle

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