Interoception
Chapter 4 endnote 20, from How Emotions are Made: The Secret Life of the Brain by Lisa Feldman Barrett.
Some context is:
Any movement of your body is accompanied by movement in your body. When you shift position quickly to catch a baseball, you have to breathe more deeply. To escape from a poisonous snake, your heart pumps blood faster through dilated blood vessels to rush glucose to your muscles, which increases your heart rate and changes your blood pressure. Your brain represents the sensations that result from this inner motion; this representation, you may remember, is called interoception.
Interoception was originally defined by the Nobel Laureate Sir Charles Scott Sherrington as sensory representations of the interior of the body (sometimes called the viscera or the internal milieu), which were thought to be driven by sensory inputs that ascend from the body to the brain.[1] The neuroanatomist Bud Craig has expanded the definition of interoception to include representations of sensory input that signal the condition of the entire body.[2] His definition includes sensory inputs related to tissue damage (nociception), temperature (thermosensation), and any sensory input that is carried by small diameter sensory neurons of the lamina I spinothamalic tract and the vagus nerve. He also includes sensations from joints, tendons, and muscle movements (proprioception), as well as information about your body’s movement and position in space to communicate that indeed, your body is now standing up. Specific neurons within muscles send signals to the brain about the metabolic conditions of the body. Craig even conceives of the skin as an organ of the body (e.g., your nociceptors can be changed when inflammation due to fever causes a metabolic change in the skin).