High-resolution dynamic neural correlates and functional connectivity of autobiographical memory retrieval
Charles Ferris1, Cory Inman1, G. Andrew James2, Stephan Hamann1; 1Emory University, 2University of Arkansas for Medical Sciences
Autobiographical memory (AM) retrieval is a complex process that recruits dynamically changing networks of brain regions as processing shifts between memory search, access, and content elaboration. In prior fMRI work we have characterized whole-brain changes in dynamic connectivity during AM retrieval, highlighting time-varying engagement of the hippocampus, PFC, and other regions. This study extended these investigations, using high temporal (TR = 1 second) and spatial (2 mm isotropic) resolution fMRI, an optimized experimental design, and both covert and overt (spoken) retrieval to test theoretical accounts of AM retrieval. After a low-level baseline task, participants retrieved unrehearsed AMs to cue words across a long retrieval period, followed by ratings of vividness and emotion. Similar to previous studies, we found a core network of brain regions including the hippocampus, medial and lateral prefrontal cortex, and the inferior parietal lobule which were active during both phases of AM retrieval. Dynamic changes between early and late processes included greater activation of the amygdala, hippocampus, and left TPJ during access, and greater activation of the superior temporal gyrus, anterior temporal lobe, and premotor cortex during elaboration processes. Graph theory analysis of dynamic functional connectivity between core AM regions was performed to characterize differences in interregional connectivity and whole-brain topological re-organization observed between early and late AM retrieval. These findings provide evidence that accessing and reconstructing autobiographical memories involves the activation of memory networks that reflect temporally varying retrieval processes and extends past studies by showing that these changes occur at faster timescales than previously described.
Topic Area: LONG-TERM MEMORY: Episodic