This study aimed to investigate whether interindividual differences in autonomic inhibitory control predict safety learningand fear extinction in an interoceptive fear conditioning paradigm. Data from a previously reported study (N = 40) wereextended (N = 17) and re-analyzed to test whether healthy participants’ resting heart rate variability (HRV) - a proxy ofcardiac vagal tone - predicts learning performance. The conditioned stimulus (CS) was a slight sensation of breathlessnessinduced by a flow resistor, the unconditioned stimulus (US) was an aversive short-lasting suffocation experience induced bya complete occlusion of the breathing circuitry. During acquisition, the paired group received 6 paired CS-US presentations;the control group received 6 explicitly unpaired CS-US presentations. In the extinction phase, both groups were exposed to6 CS-only presentations. Measures included startle blink EMG, skin conductance responses (SCR) and US-expectancy ratings.Resting HRV significantly predicted the startle blink EMG learning curves both during acquisition and extinction. In theunpaired group, higher levels of HRV at rest predicted safety learning to the CS during acquisition. In the paired group,higher levels of HRV were associated with better extinction. Our findings suggest that the strength or integrity of prefrontalinhibitory mechanisms involved in safety- and extinction learning can be indexed by HRV at rest.
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