The association between serotonin transporter availability and the neural correlates of fear bradycardia
Reduced expression of the serotonin transporter (5-HTT) is associated with susceptibility to stress-related psychopathology, but the underlying mechanisms remain elusive. We investigated whether an aberrant physiological and neural response to threat underlies this increased vulnerability. In a cross-species approach, we investigated the association between genetically encoded differences in 5-HTT expression and the neural correlates of fear bradycardia, a defensive response linked to vigilance. In both humans and rats, reduced 5-HTT expression was associated with exaggerated bradycardia or bradycardia-associated freezing, reduced activity of the medial prefrontal cortex, and increased threat-induced amygdala-periaqueductal grey connectivity and central amygdala somatostatin neuron activity. We have delineated a previously unknown neurogenetic mechanism underlying individual differences in the expression of anticipatory threat responses, contributing to stress sensitivity.
P. Schipper, M. Hiemstra, K. Bosch, D. Nieuwenhuis, A. Adinolfi, S. Glotzbach, B. Borghans, D. Lopresto, G. Fernández, F. Klumpers, E. Hermans, K. Roelofs, M. Henckens, Judith R. Homberg. (2019). The association between serotonin transporter availability and the neural correlates of fear bradycardia. Proceedings of the National Academy of Sciences.