Successful verbal retrieval in elderly subjects is related to concurrent hippocampal and posterior cingulate activation.
OBJECTIVE
Memory decline and hippocampal atrophy are two major aspects of Alzheimer's disease. Using a response-related fMRI design, we investigated the relationship between successful verbal retrieval and concurrent cerebral activation in elderly subjects in different stages of cognitive decline. We chose a correlational over the more traditional categorical approach to increase the power of detecting relevant activations.


METHODS
Eleven subjects with Alzheimer's disease, 21 elderly subjects with mild cognitive impairment, and 29 age-matched cognitively unimpaired subjects learned 180 nouns. While measuring brain activation with fMRI, the subjects had to classify these 180 learned plus 180 new distractor words as known or new. Response-related fMRI analysis was used to identify cerebral activation by correctly remembered words (hits) that correlated with retrieval success in the whole group.


RESULTS
Successful verbal retrieval was significantly correlated with concurrent activation of the left hippocampus and posterior cingulate gyrus.


CONCLUSIONS
The study confirms the importance of adequate hippocampal function for successful verbal retrieval in the elderly. In addition, our study supports connectivity studies indicating a functional relationship between the hippocampus and the posterior cingulate gyrus during successful verbal retrieval in the elderly in different stages of cognitive decline.
Heun
Reinhard
R
Department of Psychiatry, University of Birmingham, Birmingham, UK. r.heun@bham.ac.uk
Freymann
Katrin
K
Erb
Michael
M
Leube
Dirk T
DT
Jessen
Frank
F
Kircher
Tilo T
TT
Grodd
Wolfgang
W
D000368:Aged; D000544:Alzheimer Disease / Q000473:pathology / Q000523:psychology; D005260:Female; D006179:Gyrus Cinguli / Q000473:pathology / Q000502:physiology*; D006624:Hippocampus / Q000473:pathology / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory / Q000502:physiology; D011939:Mental Recall / Q000502:physiology*; D009483:Neuropsychological Tests; D021641:Recognition, Psychology / Q000502:physiology; D013702:Temporal Lobe / Q000502:physiology