Posttraumatic Stress Disorder Is Associated with α Dysrhythmia across the Visual Cortex and the Default Mode Network

Area of Science:

• Neuroscience
• Psychiatry
• Brain Oscillations

Background:

• Posttraumatic stress disorder (PTSD) is associated with distinct alterations in brain activity, including the default mode network (DMN) and alpha (α) oscillations.
• Previous research suggests α oscillations play a role in DMN function through synchronization and sensory inhibition, but a unifying pathology in PTSD remains unclear.

Purpose of the Study:

• To investigate a unifying hypothesis of α deficits within the visual cortex-DMN system as a neural underpinning of PTSD.
• To examine the relationship between α activity, DMN function, and hypervigilance symptoms in patients with PTSD compared to generalized anxiety disorder (GAD) and healthy controls (HCs).

Main Methods:

• High-density electroencephalogram (hdEEG) was recorded from 25 PTSD patients, 24 GAD patients, and 20 HCs during eyes-open resting state (S-RS) and a modified resting state (M-RS) with visual stimuli.
• Intracortical α activity (power and Granger causality) was analyzed using exact low-resolution electromagnetic tomography (eLORETA).
• Analyses focused on the visual cortex (VC), posterior cingulate cortex (PCC), and medial prefrontal cortex (mPFC) as key DMN hubs.

Main Results:

• Patients with PTSD exhibited significantly reduced α power in the VC, PCC, and mPFC compared to GAD and HC groups during both resting states.
• Reduced α power in these regions correlated with the severity of hypervigilance symptoms in PTSD patients.
• During M-RS, PTSD patients showed decreased α-frequency directed connectivity from the VC to DMN hubs (PCC, mPFC) and within the DMN (PCC→mPFC), indicating impaired inter-network communication.

Conclusions:

• The findings reveal interrelated α deficits in the visual cortex and DMN in PTSD, supporting a unifying neural pathology.
• These α dysrhythmias contribute to observed DMN hypoactivity, sensory disinhibition, and hypervigilance in PTSD.
• Targeting visual-cortex-DMN α oscillations presents a novel therapeutic avenue for network-based interventions in PTSD.