The relationship between heart rate variability and the neural mechanisms of freezing in police officers
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2016-07-01
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en
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Freezing, defined as a complete absence of movement, is a defensive response observed after threat detection in both humans and animals. It is characterized by heart rate deceleration, also called bradycardia, caused by the parasympathetic autonomic nervous system. The periaqueductal grey (PAG) is involved in the neural mechanism underlying freezing behavior. Furthermore, studies in humans suggest that differences in freezing responses may have consequences for the development or maintenance of psychopathology. Resting heart rate variability (HRV) reflects the ability of the parasympathetic nervous system to rapidly modulate the heart rate which is necessary for flexible responding to the constantly changing environment with physiological and emotional arousal. Therefore resting HRV is thought to be an index of someone’s emotion regulation capacity and linked to psychopathological vulnerability. Here we study the relationships between resting HRV, trait anxiety and freezing during threat anticipation in police officers using an active shooting paradigm. Replication of the correlation between BOLD responses in the PAG and bradycardia during threat anticipation confirmed the involvement of the PAG in freezing behavior. We were the first one to show a relation between resting HRV and stimulus induced bradycardia, which suggests a common neural mechanism. Furthermore, BOLD responses in the PAG correlated negatively with reaction time, confirming the link between freezing and action preparation processes. Identifying the link between resting HRV, as psychopathologic vulnerability factor and defensive responses such as freezing will shed light on the involvement of differences in defensive responding in the development and maintenance of fear related psychopathology.
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Faculteit der Sociale Wetenschappen