title: Selective disruption of hippocampus-mediated recognition memory processes after episodes of transient global amnesia.
abstract: Transient global amnesia (TGA) is characterized by the abrupt onset of severe amnesia without concomitant focal neurological symptoms. Recent studies revealed that small and punctate MR-signal diffusion-weighted imaging (DWI) lesions can be found within the hippocampus of TGA patients during the post-acute phase. On the basis of dual-process models of recognition memory, the present study examined the hypothesis that hippocampal dysfunction as suggested by these DWI lesions disrupts hippocampus-mediated recollection in patients with TGA, whereas familiarity-based recognition memory that is assumed to be supported by extra-hippocampal brain regions should be unaffected. We administered a recognition memory task for faces and words to eleven TGA patients during the post-acute phase and to eleven matched controls. Receiver operating characteristics (ROCs) were obtained in order to derive estimates of familiarity and recollection by applying a formal dual-process model of recognition memory. Analyses of ROC curves revealed a disruption of recollection in TGA patients' memory for words [t(20)=2.70, p<.05], but no difference in familiarity-based recognition memory between patients and controls [t(20)=-1.10, p=.284]. Post hoc analyses indicated that the deficit in recollection is more pronounced in TGA patients who show visible hippocampal lesions on diffusion-weighted MR imaging compared to those without detectable hippocampal lesions. In conclusion, consistent with recent neuroanatomical dual-process models of recognition memory, hippocampal dysfunction in patients with TGA is associated with a selective effect on specific recognition memory subprocesses.
authors.affiliation: Department of Neurology, Universitätsklinikum Mannheim, University of Heidelberg, Theodor-Kutzer-Ufer 1-3, D-68167 Mannheim, Germany. jaeger@neuro.ma.uni-heidelberg.de
authors.forename: Theodor
authors.initials: T
authors.lastname: Jäger
authors.forename: Kristina
authors.initials: K
authors.lastname: Szabo
authors.forename: Martin
authors.initials: M
authors.lastname: Griebe
authors.forename: Hansjörg
authors.initials: H
authors.lastname: Bäzner
authors.forename: Johanna
authors.initials: J
authors.lastname: Möller
authors.forename: Michael G
authors.initials: MG
authors.lastname: Hennerici
mesh_terms: D000368:Aged; D020236:Amnesia, Transient Global / Q000473:pathology* / Q000503:physiopathology*; D016022:Case-Control Studies; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D004192:Discrimination, Psychological; D005260:Female; D006624:Hippocampus / Q000503:physiopathology*; D006801:Humans; D008297:Male; D011939:Mental Recall / Q000502:physiology; D008875:Middle Aged; D009483:Neuropsychological Tests; D012372:ROC Curve; D021641:Recognition, Psychology / Q000502:physiology*