A Neurosensory Account of Anxiety and Stress (Study 1)

This study includes experiments 1a \& 1b to address Aims 1 and -- Intrinsic and Novelty-related Sensory Cortical (SC) Disinhibition and Sensory-Prefrontal-cortex-Amygdala (SPA) pathology in PTSD. The goal of this study is to develop and test a novel pathophysiology of PTSD by integrating sensory cortical (SC) and amygdala-prefrontal cortex (PFC) dysfunctions into a tripartite Sensory-Prefrontal-Cortex-Amygdala (SPA) model. The investigators will recruit 80 healthy subjects and 80 patients with PTSD in a randomized, double-blind, controlled design, where they be randomly assigned to 1) Transcranial Alternating Current Stimulation (tACS) at individual alpha peak frequency (active condition); 2) sham control tACS; or 3) active control, which will be transcranial random noise stimulation (tRNS) (random frequency 1-200 Hz). During tACS/sham tACS/tRNS stimulation, stimulation electrodes will be placed inside the holders of an EEG cap attached to the head of the participant. Simultaneous EEG- fMRI recordings during the resting state (in experiment 1a) and during a novelty task (in experiment 1b) will be acquired before and after tACS/tRNS stimulation.