Format

Send to

Choose Destination
Hippocampus. 2014 Jul;24(7):773-83. doi: 10.1002/hipo.22268. Epub 2014 Mar 21.

Hippocampal output area CA1 broadcasts a generalized novelty signal during an object-place recognition task.

Author information

1
Center for Integrative Neuroscience and Department of Physiology, University of California, San Francisco, San Francisco, California.

Abstract

Animals display an innate preference for novelty, spending more time exploring both novel objects and familiar objects in novel locations. This increase in exploration is thought to allow the animal to gather the information necessary to encode new experiences. Despite extensive evidence that increased exploration following spatial change requires the hippocampus, the pattern of hippocampal activity that supports this behavior remains unknown. We examined activity in hippocampal output area CA1 and one synapse upstream in area CA3 while freely behaving rats performed an object-place recognition task. We found that the presence of novelty substantially altered activity in CA1, but not in CA3. During exploration of displaced familiar objects and novel objects in unexpected locations, CA1 place cells showed robust increases in firing rate. These firing rate increases persisted during sharp wave ripples, when place cell representations of previous experiences are replayed. Unexpectedly, increases in CA1 activity were not spatially restricted to regions of the environment that underwent change, indicating a generalized novelty signal. We suggest that hippocampal area CA1 broadcasts the presence of novelty, rather than signaling what is novel, and simultaneously becomes more plastic, allowing the integration of new information into previously stored memories.

KEYWORDS:

CA3; learning and memory; memory reactivation; place cell; sharp wave ripple

PMID:
24596296
PMCID:
PMC4065199
DOI:
10.1002/hipo.22268
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Wiley Icon for PubMed Central
Loading ...
Support Center