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Poster B20

Heightened E/I ratio associated with PTSD and alpha-frequency dysconnectivity between the Visual Cortex and Default Mode Network

Poster Session B - Sunday, April 14, 2024, 8:00 – 10:00 am EDT, Sheraton Hall ABC

Zhaohan Wu1 (, Wen Li2; 1Florida State University, 2The University of Texas Health Science Center at Houston

Deficiency in power of alpha oscillations in the default mode network (DMN) and visual cortex (VC) and in alpha-frequency directed connectivity between the two systems has been associated with posttraumatic stress disorder (PTSD) (Clancy, et al., 2017 & 2021). However, the mechanism of this deficiency has not been elucidated. To address that gap in the literature, we investigated cortical excitation and inhibition (E/I) balance in patients with PTSD (N=25) and its association with alpha power and alpha-frequency connectivity for key areas of the DMN and the visual cortex VC, relative to two control groups [patients with generalized anxiety disorder (GAD; N=24) and healthy controls (HCs; N=20)]. High-density electroencephalogram (hdEEG) was recorded in a standard eyes-open resting state (S-RS) and a modified resting state (M-RS) of passively viewing salient images, from which aperiodic (1/f-like) exponent of resting-state EEG power spectrum (indexing E/I balance) and source-level alpha connectivity (Granger causality) was extracted using the exact low-resolution electromagnetic tomography(eLORETA). Our findings revealed that PTSD patients exhibited a significantly higher E/I ratio during S-RS compared to control groups. Additionally, diminished alpha-frequency connectivity from VC to the posterior hub of the DMN (posterior cingulate cortex/PCC) and from the anterior hub of the DMN (medial prefrontal cortex/mPFC) to PCC was observed in individuals displaying higher E/I ratios across both S-RS and M-RS. These results suggest an association between heightened cortical excitation or weakened cortical inhibition and reduced connectivity to PCC. Results also highlight the potential role of elevated E/I ratio as a mechanistic biomarker of PTSD.

Topic Area: EMOTION & SOCIAL: Other


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