Poster D1, Monday, March 27, 8:00 – 10:00 am, Pacific Concourse
Large-scale network fMRI connectivity increases caused by autobiographical memory retrieval
Kristen Warren1, Sungshin Kim1, Molly Hermiller1, Aneesha Nilakantan1, Jon O'Neil1, Robert Palumbo1, Joel Voss1; 1Northwestern University
The Default Mode Network (DMN) can be reliably identified via resting-state fMRI and is thought to reflect self-generated memory retrieval. Indeed, the DMN significantly overlaps with regions involved in autobiographical memory retrieval (ABM), suggesting it supports the self-referential memory retrieval that occurs as subjects daydream during fMRI rest periods. However, there have been few direct comparisons between DMN and ABM networks within the same subjects and with similar fMRI parameters. Here we aimed to characterize fMRI connectivity differences between resting-state and ABM retrieval using a novel ABM task involving long periods of directed retrieval intended to mimic retrieval that would normally occur during resting-state fMRI. Whole-brain, global-connectedness analysis of data from 22 subjects was used to identify regions with significantly different global connectedness levels for resting-state versus ABM. This analysis identified a set of regions, including much of the DMN, with increased connectedness during the novel ABM task versus during resting state. These global connectedness differences were driven by a large, distributed network, involving DMN and ABM regions as well as a variety of others. All regions demonstrated higher fMRI connectivity during the ABM task than during rest. These results suggest that although the DMN is engaged during rest, it is far more robustly engaged during directed autobiographical retrieval, even when the ABM task is designed to mimic the daydreaming that would occur during resting-state. Further, ABM recruits large-scale distributed networks. Relevance to understanding the nature of the memory retrieval that occurs during the resting state will be discussed.
Topic Area: LONG-TERM MEMORY: Other