Structure and Function of the Human Insula

Abstract

The insular cortex, or "Island of Reil," is hidden deep within the lateral sulcus of the brain. Subdivisions within the insula have been identified on the basis of cytoarchitectonics, sulcal landmarks, and connectivity. Depending on the parcellation technique used, the insula can be divided into anywhere between 2 and 13 distinct subdivisions. The insula subserves a wide variety of functions in humans ranging from sensory and affective processing to high-level cognition. Here, we provide a concise summary of known structural and functional features of the human insular cortex with a focus on lesion case studies and recent neuroimaging evidence for considerable functional heterogeneity of this brain region.

Figure 1

Illustration of the human insular cortex with its broad functional differentation. AC, accessory gyrus; AS, anterior short insular gyrus; MS, middle short insular gyrus; PS, posterior short insular gyrus; AL, anterior long insular gyrus; PL, posterior long insular gyrus; CIS, central insular sulcus. Estimated functional differentiation was inspired from Kurth et al. (2010)’s meta-analysis on functional neuroimaging experiments: red = sensorimotor; yellow = chemosensory; blue = social-emotional; green = cognitive. Illustration of the insular cortex offered by Dr. Tram Nguyen.

Figure 2. Multi-modal parcellation of the human insular cortex

Thirteen areas in the insula have been identified based on cortical architecture, functional activation, connectivity, and/or topography. Reproduced with permission from Glasser et al. 2016.