Neural Overlap in Item Representations Across Episodes Impairs Context Memory

Ghootae Kim, Kenneth A. Norman, Nicholas B. Turk-Browne

Research output: Contribution to journalArticle

Abstract

We frequently encounter the same item in different contexts, and when that happens, memories of earlier encounters can get reactivated. We examined how existing memories are changed as a result of such reactivation. We hypothesized that when an item's initial and subsequent neural representations overlap, this allows the initial item to become associated with novel contextual information, interfering with later retrieval of the initial context. Specifically, we predicted a negative relationship between representational similarity across repeated experiences of an item and subsequent source memory for the initial context. We tested this hypothesis in an fMRI study, in which objects were presented multiple times during different tasks. We measured the similarity of the neural patterns in lateral occipital cortex that were elicited by the first and second presentations of objects, and related this neural overlap score to subsequent source memory. Consistent with our hypothesis, greater item-specific pattern similarity was linked to worse source memory for the initial task. In contrast, greater reactivation of the initial context was associated with better source memory. Our findings suggest that the influence of novel experiences on an existing context memory depends on how reliably a shared component (i.e., item) is represented across these episodes.

Original languageEnglish (US)
Pages (from-to)2682-2693
Number of pages12
JournalCerebral Cortex
Volume29
Issue number6
DOIs
StatePublished - Jun 1 2019

All Science Journal Classification (ASJC) codes

  • Cognitive Neuroscience
  • Cellular and Molecular Neuroscience

Keywords

  • item representation
  • multivariate pattern analysis
  • neural overlap
  • source memory

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