Alternations in functional connectivity of amygdalar subregions under acute social stress

Abstract

The amygdala has long been considered a vital region involved in acute and chronic stress responses. Extensive evidences from animal and human studies suggest that the functional connectivity of amygdalar subnuclei (basolateral amygdala (BLA), centromedial amygdala (CMA) and superficial amygdala (SFA)) undergo specific alterations in stress-related psychopathology. However, whether and how intrinsic functional connectivity within the amygdalar subcomponents is differently altered in the aftermath of an acute stressor remains unknown. In the present study, using a within-subject design, we examined the impact of acute psychological social stress on the functional connectivity of amygdalar subregions at rest. Results showed that stress mainly affected the connectivity pattern of CMA. In particular, in the stress condition compared with the control, the connectivity of CMA to left posterior cingulate cortex and right thalamus was decreased under stress, while the connectivity of CMA to left caudate connectivity was increased at rest post-stressor. The findings suggest that healthy individuals may adapt to threatening surroundings by reducing threatening information input, and shifting to well-learned procedural behaviors.

Keywords: Amygdala; Functional connectivity; Stress; Subregions.

Fig. 1

Experimental procedure and manipulation check. (A) The timeline of the experiment. After an acclimation period of 20 min following arrival, participants were required to go through the Trier Social Stress Test (TSST) with (the stress condition) or without (the control condition) social evaluative processes. After the formal tasks, resting state data were collected. Saliva samples were collected at T1, T3, T4, T5, and T6. Affective ratings were collected at T1, T2, T3, T4, T5, and T6. (B) Cortisol and positive/negative emotional responses under control and stress condition. *p < 0.05, **p < 0.01, ***p < 0.001.

Fig. 2

Brain areas showing differential connectivity to the centromedial (CMA), the basolateral amygdala (BLA) or superficial amygdala (SFA) during resting-state functional magnetic resonance imaging. (A) difference between CMA and BLA; (B) difference between CMA and SFA; (C) difference between BLA and SFA.

Fig. 3

Brain clusters significant or marginally significant for group X subregion interaction. The average connectivity (βweights) were extracted from (A) the left caudate, (B) the right IFG, (C) the left PCC, and (D) the right thalamus. CM, centromedial; BL, basolateral; SF, superficial; IFG, inferior frontal gyrus; PCC, posterior cingulate cortex. *p < 0.05, **p < 0.01.