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Behavioural Neurology
Volume 11, Issue 3, Pages 163-172
http://dx.doi.org/10.1155/1999/892074

Storage of Verbal Associations Is Sufficient to Activate the Left Medial Temporal Lobe

Andrew R. Mayes,1 Patricia A. Gooding,2 Nicola M. Hunkin,1 Julia A. Nunn,1 Lloyd J. Gregory,3 Michael J. Brammer,4 Edward T. Bullmore,4 Vincent Giampietro,4 Rob Van Eijk,2 Amanda K. Nicholas,1 and Steve C. R. Williams3

1Department of Clinical Neurology, University of Sheffield, Sheffield S10 2JF, UK
2Department of Psychology, University of Strathclyde, Glasgow G1 1XQ, UK
3Neuroimaging Unit, Institute of Psychiatry, De Crespigny Park, London SE5 8AF, UK
4Brain Image Analysis Unit, Institute of Psychiatry, De Crespigny Park, London SE5 8AF, UK

Received 1 February 1999; Accepted 1 February 1999

Copyright © 1999 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Neuroimaging studies have shown that memory encoding activates the medial temporal lobe (MTL). Many believe that these activations are related to novelty but it remains unproven which is critical - novelty detection or the rich associative encoding it triggers. We examined MTL activation during verbal associative encoding using functional magnetic resonance imaging. First, associative encoding activated left posterior MTL more than single word encoding even though novelty detection was matched, indicating not only that associative encoding activates the MTL particularly strongly, but also that activation does not require novelty detection. Moreover, it remains to be convincingly shown that novelty detection alone does produce such activation. Second, repetitive associative encoding produced less MTL activation than initial associative encoding, indicating that priming of associative information reduces MTL activation. Third, re-encoding familiar associations in a well-established way had a minimal effect on both memory and MTL activation, indicating that MTL activation reflects storage of associations, not merely their initial representation.