ACHEMS 2019
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SPLTRAK Abstract Submission

Integration of Gustatory and Interoceptive Processing in the Human Insula

Jason Avery
National Institute for Mental Health, , ,

The homeostatic regulation of feeding behavior requires an organism to integrate information from its internal environment, including peripheral signals about the body’s energy needs, with information from its external environment, such as the palatability of food sources. The insula, which serves as the brain’s primary viscero-sensory and gustatory cortex, is a likely region in which this integration might occur. Previous human neuroimaging studies, which have separately examined tasks of visceral interoception and taste perception, identified a region within the dorsal mid-insula that seemed to be involved in both of these functionally diverse tasks.

We performed two neuroimaging studies to further examine this possibility. Within the first study, a group of healthy volunteers underwent fMRI while performing a task involving interoceptive attention to visceral sensations and a gustatory mapping task, in which sweet and neutral tastants were delivered onto their tongues during scanning. We identified distinct as well as overlapping clusters of activation for both tasks within neighboring regions of the dorsal mid-insula.

In the second study, we examined these regions of functional overlap using an fMRI-Adaptation task design, in which tastant delivery events during scanning were preceded by either interoceptive or exteroceptive attention. We observed that, within the dorsal mid-insula, the hemodynamic response to sweet tastants which followed interoception was significantly smaller than the response to tastants which followed the exteroception control condition. The results of these two studies suggest that tasks of gustation and interoception not only co-activate the same region of the dorsal mid-insula, they involve a shared population of neurons. This sensory convergence within the dorsal mid-insula could serve as one mechanism by which visceral signals from the periphery modulate the activity of brain regions involved in feeding behavior.