Circuitry and functional aspects of the insular lobe in primates including humans

James R. Augustine is a neuroanatomist at the University of South Carolina School of Medicine in Columbia, where he has worked since the late 1970s and has built a career on comparative primate neuroanatomy. His textbook Human Neuroanatomy (Academic Press, 2008; second edition 2017) is widely used; the 1996 paper in Brain Research Reviews is the canonical pre-modern synthesis of what was then known about the insula's circuitry across primates including humans.

Published in Brain Research Reviews in 1996 — a high-quality but specialised neuroanatomy venue — the piece is a synthesising review of two decades of tract-tracing, cytoarchitectonic, and lesion-method work on the insular lobe. The paper documents the insula's afferent and efferent connections in granular detail: local intrainsular projections, projections to the cingulate gyrus, connections with the amygdaloid nuclei, projections to and from the perirhinal, entorhinal, and periamygdaloid cortices, and the functional subdivisions (visceral sensory area, visceral motor area, motor association area, vestibular area, and language area). The argument is anatomical rather than functional: Augustine documents what the insula is connected to and what those connections imply about its likely functions, without making the strong consciousness-substrate claims later associated with Craig's 2009 paper.

The piece sits as the foundational anatomical review that nearly every subsequent insula paper builds on. Craig 2002 cites Augustine repeatedly as the cytoarchitectonic and circuit foundation on which the interoception argument rests; the agranular-versus- granular distinction in insular subfields that anchors Barrett and Simmons's EPIC model traces back to this kind of synthesis. The 1996 review is the layer of citation underneath the modern interoception literature — the place where the anatomy gets sourced when the functional claims need an anatomical foundation.

The stake is disciplinary, internal to neuroanatomy. Augustine had no commercial position to defend; the review is the kind of careful, slow synthesis that established neuroanatomists produce as a service to the field, and its citation life has been long and quiet. It is rarely cited in the popular interoception literature but is rarely absent from the primary-research literature. Read it before any serious engagement with insula anatomy; the modern functional claims are built on top of this layer.