Correlations between visual recognition memory and neocortical and hippocampal glucose metabolism after bilateral rhinal cortex lesions in the baboon: implications for Alzheimer's disease.
In Alzheimer's disease (AD), the rhinal cortex is the area earliest and most affected by neurofibrillary tangles, and the degree of temporoparietal glucose hypometabolism and rhinal cortex atrophy are both correlated with dementia severity. In monkeys, damage to the rhinal cortex leads to severe impairment in declarative memory, which is also affected preferentially in early AD. To investigate the contribution of rhinal alterations to the interrelationships between cerebral hypometabolism and declarative memory impairment observed in AD, we studied the effects of excitotoxic bilateral rhinal lesions in baboons on cerebral glucose consumption (CMRglc) as measured by positron emission tomography and performance on a visual recognition memory task as assessed in parallel by a delayed nonmatching-to-sample task. We reported previously that these rhinal lesions induce both a long-lasting hypometabolism in several remote brain regions (Meguro et al., 1999) and impaired memory performance (Chavoix et al., 2002). The present analysis indicates that across lesioned and sham baboons, memory scores were significantly positively correlated (p < 0.05; Spearman) with concomitant CMRglc values of several brain areas, such as neocortical associative and posterior hippocampal regions. These findings, reminiscent of those reported in AD, suggest that the neurodegenerative process that affects the rhinal cortex in early AD plays a crucial role in the pattern of brain hypometabolism and consequently in the declarative memory impairments characteristic of this disease.
Blaizot
Xavier
X
Institut National de la Santé et de la Recherche Médicale Unit 320, Université de Basse Normandie, 14000 Caen, France.
Meguro
Kenichi
K
Millien
Isabelle
I
Baron
Jean Claude
JC
Chavoix
Chantal
C
Blaizot
A Xavier
AX
D000544:Alzheimer Disease / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D004195:Disease Models, Animal; D018728:Entorhinal Cortex / Q000000981:diagnostic imaging / Q000502:physiology; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D005947:Glucose / Q000378:metabolism*; D006624:Hippocampus / Q000000981:diagnostic imaging / Q000378:metabolism*; D008297:Male; D008568:Memory / Q000502:physiology*; D019579:Neocortex / Q000000981:diagnostic imaging / Q000378:metabolism*; D009498:Neurotoxins; D010215:Papio; D020534:Parahippocampal Gyrus / Q000000981:diagnostic imaging / Q000502:physiology; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation; D014055:Tomography, Emission-Computed
D009498:Neurotoxins; D019788:Fluorodeoxyglucose F18; D005947:Glucose