title: Contributions of the medial temporal lobe to declarative memory retrieval: manipulating the amount of contextual retrieval.
abstract: We investigated how the hippocampus and its adjacent mediotemporal structures contribute to contextual and noncontextual declarative memory retrieval by manipulating the amount of contextual information across two levels of the same contextual dimension in a source memory task. A first analysis identified medial temporal lobe (MTL) substructures mediating either contextual or noncontextual retrieval. A linearly weighted analysis elucidated which MTL substructures show a gradually increasing neural activity, depending on the amount of contextual information retrieved. A hippocampal engagement was found during both levels of source memory but not during item memory retrieval. The anterior MTL including the perirhinal cortex was only engaged during item memory retrieval by an activity decrease. Only the posterior parahippocampal cortex showed an activation increasing with the amount of contextual information retrieved. If one assumes a roughly linear relationship between the blood-oxygenation level-dependent (BOLD) signal and the associated cognitive process, our results suggest that the posterior parahippocampal cortex is involved in contextual retrieval on the basis of memory strength while the hippocampus processes representations of item-context binding. The anterior MTL including perirhinal cortex seems to be particularly engaged in familiarity-based item recognition. If one assumes departure from linearity, however, our results can also be explained by one-dimensional modulation of memory strength.
authors: Department of Psychiatry, Radboud University Medical Center, Nijmegen 6500-HB, The Netherlands. i.tendolkar@psy.umcn.nl
authors: Indira
authors: I
authors: Tendolkar
authors: Jennifer
authors: J
authors: Arnold
authors: Karl Magnus
authors: KM
authors: Petersson
authors: Susanne
authors: S
authors: Weis
authors: Anke
authors: A
authors: Brockhaus-Dumke
authors: Philip
authors: P
authors: van Eijndhoven
authors: Jan
authors: J
authors: Buitelaar
authors: Guillén
authors: G
authors: Fernández
mesh_terms: D000293:Adolescent; D000328:Adult; D001931:Brain Mapping; D005260:Female; D006624:Hippocampus / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory / Q000502:physiology*; D010775:Photic Stimulation; D013702:Temporal Lobe / Q000502:physiology*