Insular cortex

The insular cortex (also often referred to as just the insula) is a structure of the human brain. It is buried in the depths of the brain, at the confluence of temporal and inferior parietal cortices.

Contrasting anterior and posterior architecture

It has regions of variable cell structure or cytoarchitecture, changing from granular in the posterior portion to agranular in the anterior portion. The insula also receives differential cortical and thalamic input along its length. The anterior insula receives a direct projection from the basal part of the ventral medial nucleus (VMb) of the thalamus and a particularly large input from the central nucleus of the amygdala. Additionally, the anterior insula itself projects to the amygdala. The posterior insula connects reciprocally with the secondary primary sensory cortex (S2) and receives input from spinothalamically activated ventral posterior inferior (VPI) thalamic nuclei.

Role in the limbic system

Overall, the insula is believed to process convergent information to produce an emotionally relevant context for sensory experience, such as disgust and feelings of unease. More specifically, the anterior insula is related more to olfactory, gustatory, vicero-autonomic, and limbic function, while the posterior insula is related more to auditory-somesthetic-skeletomotor function. Functional imaging experiments have revealed that the insula has an important role in pain experience. The insula is well situated for the integration of information relating to the affective and reactive components of pain as part of the circuitry related to fear avoidance.