title: Altered connectivity among emotion-related brain regions during short-term memory in Alzheimer's disease.
abstract: A PET study of patients with Alzheimer's disease (AD) engaged in a delayed match-to-sample face recognition task revealed that performance declines as a function of increasing delay, a pattern accompanied by reduced functional connectivity of prefrontal cortex but increased connectivity of the left amygdala. Here, we characterize the changes in interactions within this amygdalar circuit across the memory delays using structural equation modeling. The magnitude of effective connections was found to be much greater in the patients than in the controls, notably from the left amygdala to left inferior prefrontal cortex, which, in turn, influenced its right homologue. The influence from the amygdala to the left hippocampus, in contrast, was not strong in either group. We interpret this pattern of interactions as possibly reflecting the compensatory recruitment of a dynamic neural network, perhaps involved in implicit emotional processing, in the context of a faulty executive maintenance and retrieval system.
authors.affiliation: Department of Psychology, York University, 4700 Keele Street, Toronto, Ontario, Canada. shaynar@yorku.ca
authors.forename: R Shayna
authors.initials: RS
authors.lastname: Rosenbaum
authors.forename: Maura L
authors.initials: ML
authors.lastname: Furey
authors.forename: Barry
authors.initials: B
authors.lastname: Horwitz
authors.forename: Cheryl L
authors.initials: CL
authors.lastname: Grady
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000000981:diagnostic imaging / Q000503:physiopathology*; D000679:Amygdala / Q000000981:diagnostic imaging / Q000503:physiopathology*; D001931:Brain Mapping; D004644:Emotions / Q000502:physiology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D008875:Middle Aged; D009415:Nerve Net / Q000000981:diagnostic imaging / Q000503:physiopathology*; D009434:Neural Pathways / Q000000981:diagnostic imaging / Q000503:physiopathology; D009483:Neuropsychological Tests; D017397:Prefrontal Cortex / Q000000981:diagnostic imaging / Q000503:physiopathology*; D011877:Radionuclide Imaging