Electrophysiological markers of altered affective information processing in post-traumatic stress disorder

We used magnetoencephalography (MEG) to characterize the cortical and autonomic nervous system activity associated with affective information processing in PTSD. Participants were service members assigned to one of two groups based on whether they met (n = 36) or did not meet (n = 48) the DSM-V criteria for PTSD. MEG recordings were performed while participants viewed and rated for pleasantness images with positive affective valence (set 1) and neutral images (set 2). Higher amplitudes of the early (75 ms-150 ms) neuromagnetic evoked responses to positive vs. neutral images indicated that the pleasantness evoked by visual stimuli may be associated with increased early activation within a distributed cortical network. PTSD was associated with attenuated amplitude of the early evoked responses to all stimuli predominantly in right ventral and medial temporal regions. PTSD was also associated with less suppression of alpha and beta band power during the image presentation interval, as well as with delayed heart rhythm deceleration for all stimuli. Our findings are consistent with (1) an impairment in early automatic sensory processing reflecting potential difficulties with the fast engagement of a neuronal network of the appetitive motivational system in PTSD, (2) an impairment in sustained attentional control and suppression of competing neuronal activity in PTSD reflected in alterations of oscillatory brain activity, and (3) a slower engagement of the parasympathetic system in PTSD. These alterations in cortical and autonomic nervous system activity may contribute to symptoms of anhedonia/emotional numbing and can provide targets for treatments in PTSD.