Social support and fear-inhibition: an examination of underlying neural mechanisms

Abstract

Recent work has demonstrated that reminders of those we are closest to have a unique combination of effects on fear learning and represent a new category of fear inhibitors, termed prepared fear suppressors. Notably, social-support-figure images have been shown to resist becoming associated with fear, suppress conditional-fear-responding and lead to long-term fear reduction. Due to the novelty of this category, understanding the underlying neural mechanisms that support these unique abilities of social-support-reminders has yet to be investigated. Here, we examined the neural correlates that enable social-support-reminders to resist becoming associated with fear during a retardation-of-acquisition test. We found that social-support-figure-images (vs stranger-images) were less readily associated with fear, replicating prior work, and that this effect was associated with decreased amygdala activity and increased ventromedial prefrontal cortex (VMPFC) activity for social-support-figure-images (vs stranger-images), suggesting that social-support-engagement of the VMPFC and consequent inhibition of the amygdala may contribute to unique their inhibitory effects. Connectivity analyses supported this interpretation, showing greater connectivity between the VMPFC and left amygdala for social-support-figure-images (vs stranger-images).

Keywords: fear-inhibition; prepared fear suppressors; retardation-of-acquisition; social support; ventromedial prefrontal cortex.

Fig. 1.

Example of experimental trials. A. During the acquisition stage, one CS of each type (social-support-figure-image, stranger-image) was continuously presented with a co-terminating 500 ms electric shock (CS + s) and one CS of each type was never paired with shock (CS-). B. During the extinction stage, all CSs were presented on their own, in the absence of shock. Example images in figure courtesy of stockimages and posterize at FreeDigitalPhotos.net.

Fig. 2.

SCR results from the: (A) entire acquisition phase and (B) first two trials of extinction broken down by condition (social support, stranger) and reinforcement (CS+, CS-). All error bars indicate standard error.

Fig. 3.

Neural results from the acquisition phase. All error bars indicate standard error. (A) Parameter estimates for the bilateral amygdala ROI broken down by condition (social support, stranger) and reinforcement (CS+, CS-). (B) Parameter estimates for the VMPFC ROI broken down by condition and reinforcement.

Fig. 4.

VMPFC-left amygdala connectivity results from the acquisition phase broken down by condition (social support, stranger) and reinforcement (CS+, CS-). All error bars indicate standard error.