When your heart isn't in it anymore: cardiac correlates of task disengagement

Neuroscience is beginning to uncover the role of interoceptive feedback in perception, learning, and decision-making; however, the relation between spontaneous visceral and cognitive dynamics has received surprisingly little scrutiny. Here, we investigate how subjective, physiological, and behavioural indicators of arousal and attentional state vary in relation to ongoing cardiac activity and brain-heart coupling. Electroencephalogram, electrocardiogram, and pupillometric records were obtained from 65 adults during the performance of a sustained attention to response task (SART). Thought probes were intermittently administered during the SART to collect subjective reports of attentional state (on-task, mind-wandering, mind-blanking) and vigilance level (alertness vs. sleepiness). Mind-wandering and mind-blanking reports increased in frequency with time-on-task and were accompanied by decreases in alertness and pupil-linked arousal, but evinced distinct psychophysiological and behavioural profiles: While mind-wandering was associated with greater heart-rate variability and late modulation of the heartbeat-evoked potential, mind-blanking was characterised by more profound decreases in heart-rate, pupil size, and brain-heart coupling. Lower heart-rate predicted decreased vigilance and pupil size, in addition to slower, less-biased responses; increased heart-rate variability predicted more impulsive behaviour and pupil dilation. Together, these findings reveal that cardiac parameters and brain-heart connectivity measures afford complementary information about arousal states and attentional dynamics during task performance.