Hippocampal Volume and Functional Connectivity with the Default Mode Network Open Access

Aberizk, Katrina (Summer 2021)

Permanent URL: https://etd.library.emory.edu/concern/etds/6d56zz018?locale=en


Hippocampal volume (HV) appears more sensitive to environmental exposures than other brain regions. Reductions in HV have been associated with psychotic illness, as well as other stressful experiences in both healthy and clinical populations. Associations between stress-related changes in brain structure and functional connectivity (FC) have been demonstrated in animal research, yet such cross-modal brain relationships remain poorly characterized in humans. To date, there has been limited investigation of the relationship between HV and hippocampal FC. The present study examined associations between bilateral HV and mean hippocampal FC with the default mode network (DMN) during rest in healthy controls (HC) and individuals at clinical high-risk for psychosis (CHR-P). The sample included 246 CHR-P (218 non-converters and 28 converters) and 143 HC from the second phase of the North American Prodrome Longitudinal Study. Matrix regression revealed significant negative associations between HV and hippocampal FC with the inferior parietal lobe and thalamus after correcting for multiple comparisons. There was a significant interaction between group and right hippocampal FC with the left superior temporal pole in associations including bilateral HV. In HC, FC between the right hippocampus and left superior temporal pole was negatively associated with bilateral HV. There was a positive association between these variables in CHR-P. This research contributes insights regarding hippocampal cross-modal brain relationships, and findings may have implications for the role of DMN subsystems. Potential underlying mechanisms and implications for future research are discussed.

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