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Medial temporal lobe activations in recognition memory: Is stimulus category or recollection versus familiarity the crucial factor?
TAYLOR, K.J., GRAHAM, K.S., SCHWARZBAUER & HENSON, R.N.A.
Fourteenth Annual Meeting of the Cognitive Neuroscience Society, A77
Year of publication:
We have recently demonstrated that whilst amnesic patients with broad medial temporal lobe (MTL) damage are impaired in recognition memory (RM) for faces and spatial scenes, patients with damage limited to the hippocampus show a selective preservation of RM for faces. We proposed that it is the nature of scene versus face stimuli that produced the selective RM deficit associated with hippocampal damage. An alternative explanation, however, is that RM for scenes relies more heavily on hippocampally-dependent recollective processes, whereas RM for faces can be mediated by familiarity signals in adjacent cortical regions; i.e. it is the type of memory process, rather than nature of stimuli, that best explains the division of labour in the MTL. In order to disentangle these two possibilities, we conducted an fMRI study involving RM for faces and scenes, that incorporated measures of both subjective and objective levels of recollection and familiarity. Preliminary analysis of the encoding phase, contrasting subsequent “remember” responses with subsequent misses, revealed bilateral amygdala and parahippocampal activations for faces and scenes respectively. Notably, the analysis revealed no subsequent memory effects common to both stimulus categories. At retrieval, a comparison of “remember” responses with “familiar” responses revealed bilateral amygdala activation for faces, and notably bilateral mid/posterior hippocampal activation common to both stimulus categories. These results suggest that consideration of both stimulus category and recollection versus familiarity are essential when investigating the division of labour in the MTL.