Processing of slow-global auditory regularities causes larger neural responses to heartbeats in patients under minimal consciousness state, compared to unresponsive wakefulness syndrome

Objectives: Determine if contextual processing of auditory regularities (local-global paradigm) modulate the heartbeat-evoked responses (HERs), and if these modulations may provide complementary information to the auditory related potentials to facilitate the diagnose of patients with disorders of consciousness (DOC). Methods: DOC patients underwent the local-global paradigm to evaluate the cognitive processing of short/long term-auditory regularities. High-density EEG was recorded to evaluate HERs in local, global and overall conditions. Results: The global effect triggers higher HERs, as well as overall higher HER variance appears in minimally conscious patients. The variance and amplitude effects were uncorrelated, indicating different cognitive processes. Discussion: Our results corroborate previous findings on HER variance, a marker able to separate DOC without specific stimulations. HER modulations in response to global auditory irregularities represents a novel neural signature of consciousness access, which may facilitate the bedside diagnosis of state of consciousness with more affordable options to neuroimaging methods.