Invited ReviewBetter living through understanding the insula: Why subregions can make all the difference
Section snippets
Overview
The insular cortex is an expansive brain area spanning the anterior/posterior gradient of the brain in humans and animals. The insula has emerged as central in numerous subfields of neuroscience, where it seems to be an integral component of behavior in many disease and non-disease states. In recent years, clinical research of insula subregions has exploded, leading to identification of between 2 and 13 insula subregions based on anatomic and/or functional information used in the parcellation
The human insula
Unbiased clinical neuroimaging studies have long identified the insula as significantly involved in numerous behaviors, disorders, and related dysfunctions. However, many of these earlier human imaging studies failed to report specific subregions of the insula, complicating generalizable interpretations for the insula's many roles in human behavior. As will be discussed below, different subregions of the insula can have dramatically different-even seemingly diametrically opposed-roles in
Rodents and humans: promise and pitfalls of translation
Behavioral parallels between species (i.e. rodents and humans) are of particular translational value, and similarities in anatomical and functional connectivity also enhance the relevance of rodent findings to humans. However, connectivity needn't be identical between human and rodents since related regions could have similar anatomical compositions and neural circuitry that gives rise to similar behavioral functions. While rodent work holds3promise for understanding insula function, there are
Conclusion
This review was designed to comprehensively consider the functional roles of different insula subregions, comparing examples from the extensive human literature with the more limited work in rodents. Even with important species differences, there seems to be meaningful parallels between human and rodent insula contributions. Indeed, insula subregions likely play central roles for many emotion- and motivation-related behaviors, and may be particularly important for integrating sensory,
Acknowledgements
Supported by NIH-funded grants AA027774 (SWC), DA042987 (ACJ), AA027214 and AA07462 (BA), and AA024109 (FWH).
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These authors contributed equally.