Citation

Nicholson AA, Friston KJ, Zeidman P, Harricharan S, McKinnon MC, Densmore M, Neufeld RWJ, Théberge J, Corrigan F, Jetly R, Spiegel D, Lanius RA. Hum. Brain Mapp. 2017; 38(11): 5551-5561.

Affiliation

Imaging department, Lawson Health Research Institute, London, Ontario, Canada.

Copyright

(Copyright © 2017, John Wiley and Sons)

DOI

10.1002/hbm.23748

PMID

28836726

Abstract

OBJECTIVE: Posttraumatic stress disorder (PTSD) is associated with decreased top-down emotion modulation from medial prefrontal cortex (mPFC) regions, a pathophysiology accompanied by hyperarousal and hyperactivation of the amygdala. By contrast, PTSD patients with the dissociative subtype (PTSD + DS) often exhibit increased mPFC top-down modulation and decreased amygdala activation associated with emotional detachment and hypoarousal. Crucially, PTSD and PTSD + DS display distinct functional connectivity within the PFC, amygdala complexes, and the periaqueductal gray (PAG), a region related to defensive responses/emotional coping. However, differences in directed connectivity between these regions have not been established in PTSD, PTSD + DS, or controls.

METHODS: To examine directed (effective) connectivity among these nodes, as well as group differences, we conducted resting-state stochastic dynamic causal modeling (sDCM) pairwise analyses of coupling between the ventromedial (vm)PFC, the bilateral basolateral and centromedial (CMA) amygdala complexes, and the PAG, in 155 participants (PTSD [n = 62]; PTSD + DS [n = 41]; age-matched healthy trauma-unexposed controls [n = 52]).

RESULTS: PTSD was characterized by a pattern of predominant bottom-up connectivity from the amygdala to the vmPFC and from the PAG to the vmPFC and amygdala. Conversely, PTSD + DS exhibited predominant top-down connectivity between all node pairs (from the vmPFC to the amygdala and PAG, and from the amygdala to the PAG). Interestingly, the PTSD + DS group displayed the strongest intrinsic inhibitory connections within the vmPFC.

CONCLUSIONS: These results suggest the contrasting symptom profiles of PTSD and its dissociative subtype (hyper- vs. hypo-emotionality, respectively) may be driven by complementary changes in directed connectivity corresponding to bottom-up defensive fear processing versus enhanced top-down regulation. Hum Brain Mapp, 2017. © 2017 Wiley Periodicals, Inc.

© 2017 Wiley Periodicals, Inc.

Language: en

Keywords

amygdala; connectivity; dynamic causal modeling; fMRI; periaqueductal gray; posttraumatic stress disorder; prefrontal cortex