Poster F85, Tuesday, March 28, 8:00 – 10:00 am, Pacific Concourse
Functional dissociation and specialization of dentate gyrus and CA3 hippocampal subfields during episodic future thinking
Paul F. Hill1, Tobias Sweeney1, Gabriel A. Devenyi2,3, Mallar Chakravarty2,3, Rachel A. Diana1; 1Virginia Tech, 2Douglas Mental Health University Institute, 3McGill University
Neuroimaging work has demonstrated that the hippocampus is engaged when imagining future events. However, the functional contributions of distinct hippocampal subfields during the construction of hypothetical future events remain unknown. The aim of this study was to investigate the interaction between hippocampal subfield activity and qualitative future event features. Participants imagined future episodic events while undergoing high-resolution fMRI imaging and provided post-scan ratings of event detail, novelty, plausibility, and ease of construction. High-resolution structural images were delineated into hippocampal subfields using an automated segmentation protocol. Individual subject subfield masks were used to extract beta parameters from general linear model analyses and submitted to one-sample t-tests. We observed a significant negative relationship between activity in the right dentate gyrus (DG) and event plausibility during the initial event construction phase. in contrast, activity in the right CA3 subfield was negatively modulated by the level of detail during the subsequent elaboration phase as participants mentally expounded on the sensory and contextual details of an imagined event. These preliminary results provide novel mechanistic insights into the hippocampal circuitry involved with linking details from discrete experiences into an envisaged future event.
Topic Area: LONG-TERM MEMORY: Episodic