. Age and amyloid deposition are associated with functional alterations in posteromedial cortex during encoding and retrieval processes. Human Amyloid Imaging 2011 Meeting Abstracts. 2011 Jan 15;


Cortical s-amyloid deposition is a major histopathological finding in Alzheimer's disease and a likely contributor to the observed memory impairment. The posteromedial cortices are particularly vulnerable to early amyloid pathology and are thought to play a key role in both memory encoding and retrieval processes. The extent to which aging and amyloid influence modulation of fMRI activity during encoding vs retrieval remains an open question. In this study, we used in vivo amyloid imaging to investigate the impact of fibrillar amyloid burden on fMRI activity during encoding and retrieval in clinically normal older individuals.

Twenty-six young (M = 23.3) and 41 elderly (M = 70.9) subjects underwent fMRI scanning while performing a facename associative encoding and retrieval task. Elderly subjects were imaged with 11-C PiB-PET and each individualfs mean cortical PiB retention ratio was calculated. A conjunction analysis of deactivation during encoding and activation during retrieval revealed anatomical overlap in bilateral posteromedial cortices (p = 0.001). In this region, a negative correlation (r = -0.43, p = 0.02) was observed between the modulation of functional response (Ģ change of the functional response elicited during retrieval minus encoding) and age, suggesting that older individuals have a restricted dynamic range in the modulation between deactivation and activation in these regions. Among the older subjects, amyloid deposition was inversely correlated with modulation of functional response (r = -0.55, p Our study supports the hypothesis that the posteromedial cortices represent a critical node in episodic memory function and exhibit a dynamic response to encoding and retrieval processes. As these regions are vulnerable to early amyloid deposition, our findings may serve to elucidate the neural underpinnings of memory dysfunction seen in aging and neurodegenerative disease.


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  1. Miami: HAI Amyloid Imaging Conference Abstracts