title: Hippocampal Contributions to the Large-Scale Episodic Memory Network Predict Vivid Visual Memories.
abstract: A common approach in memory research is to isolate the function(s) of individual brain regions, such as the hippocampus, without addressing how those regions interact with the larger network. To investigate the properties of the hippocampus embedded within large-scale networks, we used functional magnetic resonance imaging and graph theory to characterize complex hippocampal interactions during the active retrieval of vivid versus dim visual memories. The study yielded 4 main findings. First, the right hippocampus displayed greater communication efficiency with the network (shorter path length) and became a more convergent structure for information integration (higher centrality measures) for vivid than dim memories. Second, vivid minus dim differences in our graph theory measures of interest were greater in magnitude for the right hippocampus than for any other region in the 90-region network. Moreover, the right hippocampus significantly reorganized its set of direct connections from dim to vivid memory retrieval. Finally, beyond the hippocampus, communication throughout the whole-brain network was more efficient (shorter global path length) for vivid than dim memories. In sum, our findings illustrate how multivariate network analyses can be used to investigate the roles of specific regions within the large-scale network, while also accounting for global network changes.
authors.affiliation: Department of Psychology and Neuroscience, Duke University, Durham, NC 27708, USA.
authors.forename: Benjamin R
authors.initials: BR
authors.lastname: Geib
authors.affiliation: Department of Psychology and Neuroscience, Duke University, Durham, NC 27708, USA.
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Stanley
authors.affiliation: Department of Psychology and Neuroscience, Duke University, Durham, NC 27708, USA.
authors.forename: Erik A
authors.initials: EA
authors.lastname: Wing
authors.affiliation: Laboratory for Complex Brain Networks, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Laurienti
authors.affiliation: Department of Psychology and Neuroscience, Duke University, Durham, NC 27708, USA.
authors.forename: Roberto
authors.initials: R
authors.lastname: Cabeza
mesh_terms: D000293:Adolescent; D000328:Adult; D001931:Brain Mapping; D005260:Female; D007839:Functional Laterality; D006624:Hippocampus / Q000000981:diagnostic imaging / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D061212:Memory, Episodic; D011939:Mental Recall / Q000502:physiology*; D015999:Multivariate Analysis; D009434:Neural Pathways / Q000000981:diagnostic imaging / Q000502:physiology; D009483:Neuropsychological Tests; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult
keywords: declarative memory; functional magnetic resonance imaging; graph theory; medial temporal lobes; recall