Importance: Posttraumatic stress disorder (PTSD) and resilience reflect 2 distinct outcomes after exposure to potentially traumatic events. The neural mechanisms underlying these different outcomes are not well understood. Objective: To examine the effect of trauma on synchronous neural interactions for veterans with PTSD and resilient controls using magnetoencephalography. Design: Participants underwent diagnostic interviews, a measure of exposure to potentially traumatic events, and magnetoencephalography. Setting: US Department of Veterans Affairs medical center. Participants: Eighty-six veterans with PTSD and 113 resilient control veterans recruited from a large Midwestern medical center. Main Outcome Measures: Multiple regression analyses were performed to examine the effect of lifetime trauma on global and local synchronous neural interactions. In analyses examining the local synchronous neural interactions, the partial regression coefficient indicates the strength and direction of the effect of trauma on the synchronous interactions between the 2 neural signals recorded by a pair of sensors. The partial regression coefficient, or slope, is the primary outcomemeasure for these analyses. Results: Global synchronous neural interactions were significantly modulated downward with increasing lifetime trauma scores in resilient control veterans (P=.003) but not in veterans with PTSD (P=.91). This effect, which was primarily characterized by negative slopes (ie, decorrelations) in small neural networks, was strongest in the right superior temporal gyrus. Significant negative slopes were more common, stronger, and observed between sensors at shorter distances than positive slopes in both hemispheres (P<.001 for all) for controls but not for veterans with PTSD. Conclusions: Neural modulation involving decorrelation of neural networks in the right superior temporal gyrus and, to a lesser extent, other areas distinguishes resilient veterans from those with PTSD and is postulated to have an important role in healthy response to trauma.