Contributions of the insula to cognition and emotion.

Historically, the insula was considered primary gustatory cortex. Now it is known to play a more comprehensive role in the processing of sensory information, including acting as primary cortex for interoceptive information, including autonomic nervous system mediated changes. As such, it is critical for emotional feeling in accord with the James-Lange theory, a role previously ascribed to the limbic system. Neuroimaged abnormal grey matter volumes or activity levels in the insula have been associated with schizophrenia, eating disorders, anxiety and mood disorders, conduct disorder, autism, addiction, and chronic pain. The significance of these abnormal activity patterns remains theoretical. Neuropsychological studies have linked dominant insula injury with various symptoms of aphasia, but its exact role in language processing remains uncertain as most cases involve lesions that extend into perisylvian language zones. Functional neuroimaging studies have found insula hyper-activations, typically in conjunction with anterior cingulate cortex, for all manner of experimental tasks including those involving perception, intentional action, and consciousness. Such neuroimaged activity is unlikely to be task-specific, but rather reflective of generic changes in autonomic activity in response to salience, homeostatic incongruence, or cognitive challenge.