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Activity of human hippocampal and amygdala neurons during retrieval of declarative memories

Rutishauser, Ueli and Schuman, Erin M. and Mamelak, Adam N. (2008) Activity of human hippocampal and amygdala neurons during retrieval of declarative memories. Proceedings of the National Academy of Sciences of the United States of America, 105 (1). pp. 329-334. ISSN 0027-8424. PMCID PMC2224211. doi:10.1073/pnas.0706015105.

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Episodic memories allow us to remember not only that we have seen an item before but also where and when we have seen it (context). Sometimes, we can confidently report that we have seen something (familiarity) but cannot recollect where or when it was seen. Thus, the two components of episodic recall, familiarity and recollection, can be behaviorally dissociated. It is not clear, however, whether these two components of memory are represented separately by distinct brain structures or different populations of neurons in a single anatomical structure. Here, we report that the spiking activity of single neurons in the human hippocampus and amygdala [the medial temporal lobe (MTL)] contain information about both components of memory. We analyzed a class of neurons that changed its firing rate to the second presentation of a previously novel stimulus. We found that the neuronal activity evoked by the presentation of a familiar stimulus (during retrieval) distinguishes stimuli that will be successfully recollected from stimuli that will not be recollected. Importantly, the ability to predict whether a stimulus is familiar is not influenced by whether the stimulus will later be recollected. We thus conclude that human MTL neurons contain information about both components of memory. These data support a continuous strength of memory model of MTL function: the stronger the neuronal response, the better the memory.

Item Type:Article
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URLURL TypeDescription Information CentralArticle
Rutishauser, Ueli0000-0002-9207-7069
Schuman, Erin M.0000-0002-7053-1005
Mamelak, Adam N.0000-0002-4245-6431
Additional Information:© 2007 by the National Academy of Sciences. Freely available online through the PNAS open access option. Edited by Larry R. Squire, Veterans Affairs Medical Center, San Diego, CA, and approved November 13, 2007 (received for review June 28, 2007). Published online before print December 27, 2007. We thank L. Squire, G. Kreiman, F. Mohrman and W. Einhaeuser for discussions; all patients for their participation; and the staff of the Huntington Hospital for their support. Author contributions: U.R., E.M.S., and A.N.M. designed research; U.R. and A.N.M. performed research; U.R. contributed new reagents/analytic tools; U.R. analyzed data; and U.R., E.M.S., and A.N.M. wrote the paper. The authors declare no conflict of interest. This article is a PNAS Direct Submission. This article contains supporting information online at
Subject Keywords:hippocampus; single-unit; episodic memory; recollection; recognition
Issue or Number:1
PubMed Central ID:PMC2224211
Record Number:CaltechAUTHORS:RUTpnas08
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Official Citation:Activity of human hippocampal and amygdala neurons during retrieval of declarative memories Ueli Rutishauser, Erin M. Schuman, Adam N. Mamelak Proceedings of the National Academy of Sciences Jan 2008, 105 (1) 329-334; DOI: 10.1073/pnas.0706015105
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9446
Deposited By: Archive Administrator
Deposited On:03 Jan 2008
Last Modified:08 Nov 2021 20:59

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