Gut consciousness: a perspective on visceral phenomenal awareness.

Abstract

The proposition that the enteric nervous system sustains a form of consciousness is seldom entertained in mainstream neuroscience, yet it follows from a disciplined reading of contemporary theories of mind. We argue that the 400-600 million neurons embedded in the mammalian gastrointestinal wall, taken together with the vast interoceptive surface they supervise, the enteroendocrine-immune interface, and the microbial community they co-regulate, constitute a substrate that satisfies, on several of the leading theories of consciousness, the criteria those theories use to attribute experience elsewhere. We synthesize evidence on enteric autonomy, chemo- and mechanosensory resolution, vagal and humoral signalling, self/non-self-discrimination at the epithelial-immune boundary, comparative data from invertebrates whose nervous systems are dominated by gut-like plexuses, and convergent clinical signatures (irritable bowel syndrome, food intolerances, psychedelic nausea, glucagon-like peptide-1 signalling) that are difficult to accommodate under a purely sensorimotor account. Throughout we distinguish two claims that are easily conflated: that the gut makes a large and underappreciated contribution to the single consciousness of the whole animal, and that enteric processing constitutes a second, much simpler locus of experience of its own. Most of the available evidence bears on the first, and we set out five lines of investigation that would discriminate between them. We conclude that gut consciousness is a testable hypothesis, likely corresponding to an 'animal' mode of consciousness dominated by interoceptive feel, drive and affect, and we propose empirical directions for its further investigation.