Post-traumatic stress disorder (PTSD) is often characterized by aberrant amygdala activation and functional abnormalities in corticolimbic circuitry, as elucidated by functional neuroimaging. These “activation” studies have primarily relied on tasks designed to induce region-specific, and task-dependent brain responses in limbic (e.g., amygdala) and paralimbic brain areas through the use of aversive evocative probes. It remains unknown if these corticolimbic circuit abnormalities exist at baseline or “at rest,” in the absence of fear/anxiety-related provocation and outside the context of task demands. Therefore the primary aim of the present experiment was to investigate aberrant amygdala functional connectivity patterns in combat-related PTSD patients during resting-state. Seventeen Operation Enduring Freedom/Operation Iraqi Freedom (OEF/OIF) veterans with combat-related PTSD (PTSD group) and 17 combat-exposed OEF/OIF veterans without PTSD [combat-exposed control (CEC) group] underwent an 8-min resting-state functional magnetic resonance imaging scan. Using an anatomically derived amygdala “seed” region we observed stronger functional coupling between the amygdala and insula in the PTSD group compared to the CEC group, but did not find group differences in amygdala–prefrontal connectivity. These findings suggest that the aberrant amygdala and insula activation to fear-evocative probes previously characterized in PTSD may be driven by an underlying enhanced connectivity between the amygdala, a region known for perceiving threat and generating fear responses, and the insula, a region known for processing the meaning and prediction of aversive bodily states. This enhanced amygdala–insula connectivity may reflect an exaggerated, pervasive state of arousal that exists outside the presence of an overt actual threat/danger. Studying amygdala functional connectivity “at rest” extends our understanding of the pathophysiology of PTSD.
Keywords: amygdala, resting-state, functional magnetic resonance imaging, post-traumatic stress disorder
Citation: Rabinak CA, Angstadt M, Welsh RC, Kenndy AE, Lyubkin M, Martis B and Phan KL (2011) Altered amygdala resting-state functional connectivity in post-traumatic stress disorder. Front. Psychiatry 2:62. doi: 10.3389/fpsyt.2011.00062
Received: 30 September 2011; Accepted: 28 October 2011;
Published online: 14 November 2011.
Edited by:Ben Harrison, The University of Melbourne, Australia
Reviewed by:Leonardo Fontenelle, Institute of Psychiatry at the Federal University of Rio de Janeiro, Brazil
Copyright: © 2011 Rabinak, Angstadt, Welsh, Kenndy, Lyubkin, Martis and Phan. This is an open-access article subject to a non-exclusive license between the authors and Frontiers Media SA, which permits use, distribution and reproduction in other forums, provided the original authors and source are credited and other Frontiers conditions are complied with.
*Correspondence: K. Luan Phan, Department of Psychiatry, University of Michigan, Rachel Upjohn Building, Room 2751, 4250 Plymouth Road, Ann Arbor, MI 48109-2700, USA. e-mail: email@example.com