Off-line replay maintains declarative memories
in a model of hippocampal-neocortical interactions
Szabolcs Káli Peter Dayan
Nature Neuroscience 7 286-294.
Abstract
During sleep, neural activity in the hippocampus and neocortex seems
to recapitulate aspects of its earlier, awake form. This replay
may be a substrate for the consolidation of long-term declarative
memories, whereby they become independent of the hippocampus and
are stored in neocortex. In contrast to storage, other crucial
facets of competent long-term memory, such as maintenance of
access to stored traces and preservation of their correct
interpretation, have received little attention. We investigate
long-term episodic and semantic memory in a theoretical model of
neocortical-hippocampal interaction. We find that, in the absence
of regular hippocampal reactivation, even supposedly consolidated
episodic memories are fragile in the face of cortical semantic
plasticity. Replay allows access to episodes stored in the
hippocampus to be maintained, by keeping them in appropriate
register with changing neocortical representations. Hippocampal
storage and replay also has a constructive role in the recall of
structured, semantic information.
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