Heart rate variability as an index of prefrontal neural function in military settings

In the present paper we describe a model of neurovisceral integration in which a set of neural structures involved in cognitive, affective, and autonomic regulation are related to heart rate variability (HRV) and cognitive performance. We will provide pharmacological and neuroimaging data in support of the neural structures linking the central nervous system to HRV. Next, we will review a number of studies from our group using military cadets showing that individual differences in HRV are related to performance on tasks associated with executive function and prefrontal cortical activity. In the first study, individual differences in resting HRV we related to performance on executive and non-executive function tasks. The results showed that greater HRV was associated with better performance on executive function tasks. In the second study we add a stressor (shock avoidance) to the previous paradigm and show that those with greater HRV were more stress tolerant. Specifically, those with greater HRV were not adversely affected by the added stressor. In the last experiment, HRV was manipulated by physical detraining. Again, those that maintained their HRV at the post-test showed better performance on executive function tasks. We propose that these findings have important implications for the development of biomarkers related to performance in modern warfighters.