The Neural Basis of Interoception

The underlying neural substrates of interoception have been a topic of research interest from the conceptualisation of interoception. In fact, many of the (multiple) definitions of interoception have drawn upon our understanding of neural pathways and brain regions in order to distinguish interoception from other forms of perception, and discriminate between separate facets of interoception. In this chapter, we review early and contemporary research on the neural substrates of interoception. We describe the neural and humoral pathways from peripheral sensors in the body (chemoreceptors, humoral receptors, specialised mechanoreceptors and free nerve endings) to the brain, for example via cranial nerves and spinal visceral afferents projecting to the brainstem. We then summarise the limbic and cortical regions involved in interoception, such as the thalamus, anterior insula and anterior cingulate cortex. We also discuss recent evidence regarding the integration of interoceptive information, and interactions between afferent and efferent signals at different points throughout the interoceptive neural networks. We end the chapter with a discussion of outstanding questions and priorities for future research.