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 (zwu2@fsu.edu), 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