Deficient posterior-to-frontal alpha-frequency connectivity and re-experiencing symptoms in combat-exposed veterans: a sensory model for PTSD
Kevin Clancy1, Alejandro Albizu1, Mingzhou Ding2, Wen Li1; 1Florida State University, 2University of Florida - Gainesville
Posttraumatic stress disorder (PTSD) is a neuropsychiatric disorder characterized by intrusive thoughts or flashbacks of one’s traumatic experience, often triggered by an external stimulus that could culminate in a re-experiencing of the trauma. Accompanied by symptoms of hypervigilance and the excessive scanning of ones’ environment for danger, such symptomatology implicates an aberration in memory activation due to exaggerated and distorted sensory processing. Alpha oscillations (8-12 Hz) are known to play an integral, inhibitory role in regulating sensory processing and the relay of sensory information across distal cortical regions. Using eyes-open resting-state electroencephalogram (EEG) in 37 combat-exposed veterans, we found deficits in alpha-frequency occipitoparietal-to-frontal Granger connectivity were related to greater intrusive re-experiencing symptoms, over and beyond general anxious and negative moods (β = -.30, t = -2.57, p = .015). Additionally, these deficits were related to higher ratings of combat-relatedness for presented combat-related odors (r = -.37, p = .03). Given the inhibitory nature of alpha oscillations, these associations suggest that compromised inhibition of sensory-driven, bottom-up projections could underpin intrusive thoughts and biased threat appraisal in PTSD. Furthermore, given that oscillations orchestrate large-scale resting state networks responsible for sensory-driven arousal (via the Salience Network) and auto-biographical memory (via the Default Mode Network), these data suggest that deficient posterior-to-frontal alpha-frequency connectivity could constitute a sensory mechanism of intrusive traumatic thoughts and memories in PTSD.
Topic Area: PERCEPTION & ACTION: Multisensory