Brain-heart interactions in the neurobiology of consciousness

A review of theoretical and experimental evidence suggests that brain-heart interactions play a role in consciousness, emotion, and cognition. Research in patients with disorders of consciousness shows that observing these interactions can detect residual consciousness even without behavioral signs. Studies in healthy participants indicate that neural responses to heartbeats relate to perception and self-consciousness, and mathematical modeling of physiological dynamics reveals that emotion processing begins with ascending vagal inputs to the brain, followed by sustained bidirectional brain-heart interactions. The author advocates for methodological advances in estimating brain-heart interactions to better understand their role in the origin, levels, and contents of consciousness, highlighting potential non-linear, complex communication between brain and heartbeat dynamics.

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Abstract

Recent experimental evidence on patients with disorders of consciousness revealed that observing brain-heart interactions helps to detect residual consciousness, even in patients with absence of behavioral signs of consciousness. Those findings support hypotheses suggesting that visceral activity is involved in the neurobiology of consciousness, and sum to the existing evidence in healthy participants in which the neural responses to heartbeats reveal perceptual and self-consciousness. More evidence obtained through mathematical modeling of physiological dynamics revealed that emotion processing is prompted by an initial modulation from ascending vagal inputs to the brain, followed by sustained bidirectional brain-heart interactions. Those findings support long-lasting hypotheses on the causal role of bodily activity in emotions, feelings, and potentially consciousness. In this paper, the theoretical landscape on the potential role of heartbeats in cognition and consciousness is reviewed, as well as the experimental evidence supporting these hypotheses. I advocate for methodological developments on the estimation of brain-heart interactions to uncover the role of cardiac inputs in the origin, levels, and contents of consciousness. The ongoing evidence depicts interactions further than the cortical responses evoked by each heartbeat, suggesting the potential presence of non-linear, complex, and bidirectional communication between brain and heartbeat dynamics. Further developments on methodologies to analyze brain-heart interactions may contribute to a better understanding of the physiological dynamics involved in homeostatic-allostatic control, cognitive functions, and consciousness.