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Large-scale intrinsic brain systems have been identified for exteroceptive senses (e.g., sight, hearing, touch). We introduce an analogous system for representing sensations from within the body, called interoception, and demonstrate its relation to regulating peripheral systems in the body, called allostasis. Employing the recently introduced Embodied Predictive Interoception Coding (EPIC) model, we used tract-tracing studies of macaque monkeys, followed by two intrinsic functional magnetic resonance imaging samples (N = 280 and N = 270) to evaluate the existence of an intrinsic allostatic/interoceptive system in the human brain. Another sample (N = 41) allowed us to evaluate the convergent validity of the hypothesized allostatic/interoceptive system by showing that individuals with stronger connectivity between system hubs performed better on an implicit index of interoceptive ability related to autonomic fluctuations. Implications include insights for the brain's functional architecture, dissolving the artificial boundary between mind and body, and unifying mental and physical illness.Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use: http://www.nature.com/authors/editorial_policies/license.html#terms * Corresponding authors: ian_kleckner@urmc.rochester.edu, l.barrett@neu.edu. ǂ Shared senior authorshipAuthor contributions: The study was designed by all the authors, analyzed by all the authors, and the manuscript was written by I.R.K. and L.F.B with comments and edits from other authors. Competing interests:The authors declare no competing interests. HHS Public AccessAuthor manuscript Nat Hum Behav. Author manuscript; available in PMC 2017 October 24.Published in final edited form as: Nat Hum Behav. 2017 ; 1: . doi:10.1038/s41562-017-0069. Author Manuscript Author ManuscriptAuthor Manuscript Author ManuscriptThe brain contains intrinsic systems for processing exteroceptive sensory inputs from the world, such as vision, audition, and proprioception/touch (e.g., 1 ). Accumulating evidence indicates that these systems work via the principles of predictive coding (e.g., 2-7 ), where sensations are anticipated and then corrected by sensory inputs from the world. The brain, as a generative system, models the world by predicting, rather than reacting to, sensory inputs.Predictions guide action and perception by continually constructing possible representations of the immediate future based on their prior probabilities relative to the present context 8,9 . We and others have recently begun studying the hypothesis that ascending sensory inputs from the organs and systems within the body's internal milieu are similarly anticipated and represented (i.e., autonomic visceral and vascular function, neuroendocrine fluctuations, and neuroimmune function) [10][11][12][13][14][15][16] . These sensations are referred to as interoception [17][18][19] .Engineering studies of neural design 20 , alo...

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The homeostatic regulation of feeding behavior requires an organism to be able to integrate information from its internal environment, including peripheral visceral signals about the body’s current energy needs, with information from its external environment, such as the palatability of energy-rich food stimuli. The insula, which serves as the brain’s primary sensory cortex for representing both visceral signals from the body and taste signals from the mouth and tongue, is a likely candidate region in which this integration might occur. However, to date it has been unclear whether information from these two homeostatically critical faculties is merely co-represented in the human insula, or actually integrated there. Recent functional neuroimaging evidence of a common substrate for visceral interoception and taste perception within the human dorsal mid-insula suggests a model whereby a single population of neurons may integrate viscerosensory and gustatory signals. To test this model, we used fMRI-Adaptation to identify whether insula regions that exhibit repetition suppression following repeated interoception trials would then also exhibit adapted responses to subsequent gustatory stimuli. Multiple mid and anterior regions of the insula exhibited adaptation to interoceptive trials specifically, but only the dorsal mid-insula regions exhibited an adapted gustatory response following interoception. The discovery of this gustatory-interoceptive convergence within the neurons of the human insula supports the existence of a heretofore-undocumented neural pathway by which visceral signals from the periphery modulate the activity of brain regions involved in feeding behavior.