Interoception

Interoception is the brain's sense of the body's internal state — the neural representation of signals arising from the viscera, muscles, skin, and endocrine system. Once dismissed as a minor sensory modality, interoception is now recognized as a foundational component of affective neuroscience and a necessary condition for the emotions that guide decision-making. Antonio Damasio's somatic marker hypothesis depends on it: without the brain's capacity to map bodily states, there are no markers to steer choice.

The insular cortex is the principal neural substrate of interoception, integrating visceral signals into a coherent map that the brain uses to regulate homeostasis and generate feeling states. Disruptions to interoceptive processing are implicated in anxiety disorders, addiction, and depersonalization — conditions where the sense of "being in a body" becomes unreliable or distorted. Interoception is therefore not a passive monitoring system. It is an active regulatory loop that connects the biological imperatives of survival to the phenomenology of selfhood.

Interoception is the body's whisper to the brain — and the brain's failure to listen is not a sensory deficit but a collapse of the boundary between self and world. Any theory of cognition that ignores the internal milieu is a theory of a brain in a jar, not a mind in a body.