Retrieval attempts transiently interfere with concurrent encoding of episodic memories but not vice versa

Kevin Allan, Royston Darrell Allen

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


In the rodent hippocampus, different phases of each theta activity cycle may be devoted to encoding and retrieval processes. These cycles of similar to 3 - 8 Hz would allow equal processing time for each state and also provide temporal segregation to minimize their mutual interference. Weshow here that, by controlling the presentation asynchrony between verbal encoding and retrieval cues, theta-resolution (< 100 ms) interference-free shifts between functional states are not expressed in hippocampally dependent, human "episodic" memory. Instead, retrieval attempts selectively and transiently interfere, for similar to 450 ms, with the encoding of ongoing experiences. Analyses of scalp event-related potentials confirmed that the functional state of the brain during retrieval is largely unperturbed by concurrent encoding and also suggested that encoding impairments may last until a neocortical phase of retrieval can begin. The findings reveal the dynamic properties of interdependent encoding and retrieval functions that contribute to episodic memory in vivo and, moreover, show that, in humans, this form of memory does not operate with either the equality, or the rapidity, intrinsic to the theta model of rodent hippocampal function.

Original languageEnglish
Pages (from-to)8122-8130
Number of pages8
JournalJournal of Neuroscience
Issue number36
Publication statusPublished - 7 Sept 2005


  • hippocampus
  • theta rhythm
  • episodic memory
  • encoding
  • retrieval
  • event-related potentials
  • medial temporal-lobe
  • long-term potentation
  • recognition memory
  • divided attention
  • declarative memory
  • hippocampal complex
  • novelty detection
  • working-memory
  • rhinal cortex
  • theta-rhythm


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