title: Associative learning over trials activates the hippocampus in healthy elderly but not mild cognitive impairment.
abstract: The ability to form associations between choice alternatives and their contingent outcomes is an important aspect of learning that may be sensitive to hippocampal dysfunction in memory disorders of aging such as amnestic mild cognitive impairment (MCIa), or early Alzheimer disease. In this preliminary study we examined brain activation using functional magnetic resonance imaging (fMRI) in 12 healthy elderly participants and nine patients with MCIa during an associative learning task. Using a high-field 3.0-Tesla MRI scanner, we examined the dynamic neural response during associative learning over trials. The slope of signal attenuation associated with learning was analyzed for differences between groups within an a priori defined hippocampal region. Results indicated dynamic signal attenuation associated with learning in the healthy elderly sample, but not in MCIa. The absence of an associative learning effect in the MCIa sample reaffirms an important link between the learning difficulties that are commonly encountered in MCIa and the mesial temporal region.
authors.affiliation: Geriatric Research Education and Clinical Center, Wm. S. Middleton VA Hospital, Madison, WI 53705, USA. scj@medicine.wisc.edu
authors.forename: Sterling C
authors.initials: SC
authors.lastname: Johnson
authors.forename: Taylor W
authors.initials: TW
authors.lastname: Schmitz
authors.forename: Sanjay
authors.initials: S
authors.lastname: Asthana
authors.forename: Mark A
authors.initials: MA
authors.lastname: Gluck
authors.forename: Catherine
authors.initials: C
authors.lastname: Myers
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001245:Association Learning / Q000502:physiology*; D001931:Brain Mapping; D003072:Cognition Disorders / Q000473:pathology*; D004192:Discrimination, Psychological; D005260:Female; D015577:Geriatric Assessment; D006624:Hippocampus / Q000098:blood supply / Q000503:physiopathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D009483:Neuropsychological Tests; D010100:Oxygen / Q000097:blood; D011930:Reaction Time / Q000502:physiology
chemical_list: D010100:Oxygen