title: Storage of verbal associations is sufficient to activate the left medial temporal lobe.
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.
authors.affiliation: Department of Clinical Neurology, University of Sheffield, Sheffield S10 2JF, UK.
authors.forename: Andrew R.
authors.initials: AR
authors.lastname: Mayes
authors.forename: Patricia A.
authors.initials: PA
authors.lastname: Gooding
authors.forename: Nicola M.
authors.initials: NM
authors.lastname: Hunkin
authors.forename: Julia A.
authors.initials: JA
authors.lastname: Nunn
authors.forename: Lloyd J.
authors.initials: LJ
authors.lastname: Gregory
authors.forename: Michael J.
authors.initials: MJ
authors.lastname: Brammer
authors.forename: Edward T.
authors.initials: ET
authors.lastname: Bullmore
authors.forename: Vincent
authors.initials: V
authors.lastname: Giampietro
authors.forename: Rob
authors.initials: R
authors.lastname: Van Eijk
authors.forename: Amanda K.
authors.initials: AK
authors.lastname: Nicholas
authors.forename: Steve C.R.
authors.initials: SC
authors.lastname: Williams