Heartbeat on hold: cortical processing of cardiac signals during motor preparation

The brain and heart work together to optimize responses to environmental demands, with cardiac signals influencing perception and action. Cardiac deceleration, often associated with response inhibition, enhances the brain's ability to encode stimuli and prepare for action, minimizing interference from internal signals. While this adaptive mechanism facilitates motor preparation, the reciprocal influence of cardiac signals and motor inhibition at the cortical level remains unclear. This study investigated whether context-driven motor inhibition modulates cortical cardiac signal processing, as measured by the Heartbeat-Evoked Potential (HEP). Participants completed a Go/No-Go task with two contexts: low proactive inhibition (LPI, infrequent No-Go stimuli) and high proactive inhibition (HPI, frequent No-Go stimuli). EEG and ECG analyses focused on HEPs during the pre-stimulus phase, with the hypothesis that HPI would enhance HEP amplitude, particularly during motor preparation (HEP2). Consistent with proactive inhibition strategies, participants displayed slower reaction times and reduced readiness potential (BP) amplitudes in the HPI condition, indicating reduced motor engagement during preparation compared to LPI. Crucially, HEP2 amplitudes were significantly higher during motor preparation in the HPI context, while no context-driven effects were observed for HEP1. Importantly, this modulation was independent of broader physiological adjustments, including cardiac deceleration. These findings suggest that proactive inhibition contexts specifically enhance cardiac signal processing during motor preparation. This modulation highlights a functional link between cardiac processing and motor inhibition, likely serving an adaptive role in optimizing physiological and cognitive readiness for scenarios requiring restraint and control.