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Science 6 May 2005:
Vol. 308. no. 5723, pp. 873 - 876
DOI: 10.1126/science.1108905

Reports

Attractor Dynamics in the Hippocampal Representation of the Local Environment

Tom J. Wills,1 Colin Lever,1 Francesca Cacucci,1 Neil Burgess,1,2 John O'Keefe1*

Memories are thought to be attractor states of neuronal representations, with the hippocampus a likely substrate for context-dependent episodic memories. However, such states have not been directly observed. For example, the hippocampal place cell representation of location was previously found to respond continuously to changes in environmental shape alone. We report that exposure to novel square and circular environments made of different materials creates attractor representations for both shapes: Place cells abruptly and simultaneously switch between representations as environmental shape changes incrementally. This enables study of attractor dynamics in a cognitive representation and may correspond to the formation of distinct contexts in context-dependent memory.

1 Department of Anatomy and Developmental Biology, University College London, London WC1E 6BT, UK.
2 Institute of Cognitive Neuroscience, University College London, London WC1E 6BT, UK.

* To whom correspondence should be addressed. E-mail: j.okeefe{at}ucl.ac.uk

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Science. ISSN 0036-8075 (print), 1095-9203 (online)