IC‐P‐091: Successful associative memory formation and retrieval in healthy older adults is associated with hippocampal subfield activation
Year: 2012
Type: article
Abstract: The earliest manifestations of Alzheimer's Disease (AD) include episodic memory failure and focal pathology in the medial temporal lobe (MTL). Although conventional functional neuroimaging has provided insights into broad MTL changes early in the disease, little is known about focal changes and how such changes relate to memory success and failure. Notably, many fMRI studies employ a face-name associative memory paradigm in block design format that cannot dissociate remembered and forgotten trials, rendering it difficult to disambiguate group activity differences arising from performance vs genuine circuitry differences. The aim of the current study was to investigate the utility of an event-related version of the canonical face-name task coupled with high-resolution fMRI in detecting focal MTL activity indicative of memory success. Healthy older adults underwent high-resolution structural and functional imaging of the MTL. Structural images were collected both perpendicular and parallel to the longitudinal axis of the hippocampus (in-plane resolution: 0.43 x 0.43mm 2; slice thickness: 2mm and 1.5mm, respectively). Functional images were collected with the latter orientation (in-plane resolution: 1.67 x 1.67mm 2). Participants performed an event-related face-name associative memory task while being scanned. During encoding participants were presented with both unique and repeating pairs. During retrieval participants viewed intact, recombined, and novel face-name pairs, and were asked to decide whether the face-name pairing was correct, incorrect or entirely new. Behavioral data indicate that intact, recombined and novel pairs were successfully discriminated. FMRI encoding data reveal greater activity for unique than repeating pairs in several hippocampal subfields. When unique pairs were further binned according to subsequent memory performance, greater encoding activity was seen for subsequently successful than unsuccessful trials across the hippocampus. Similarly, analyses of fMRI retrieval data reveal greater activity across several hippocampal subfields for successful than unsuccessful associative memory. Multiple hippocampal subfields exhibited increased activity during successful formation and retrieval of associative memories. Given the focal nature of MTL pathology early in AD, high-resolution fMRI used in concert with an event-related memory paradigm may be a useful tool for evaluating differences in hippocampal function at the subfield level in healthy aging and early-stage AD.
Source: Alzheimer s & Dementia
Institution: Stanford University
Language: English
Subfield: Cognitive Neuroscience
Field: Neuroscience
Domain: Life Sciences
Open Access status: bronze
OpenAlex ID: W2009565597