Figure 5. Gustatory-Interoceptive Convergence in the Dorsal Mid-Insula.

The bilateral dorsal mid-insula exhibited specific adaptation for interoception adaptation (Figure 3; pictured here in surface and volumetric cortical images) as well as significant activation to the taste of sucrose (Figure 4). These regions also exhibited an adapted response to sweet tastants following Interoception adaptation trains compared to identical sweet tastants following Exteroception adaptation trains (SWEET after Exteroception – SWEET after interoception, t(14), two-tailed paired t-test; Table 4). This demonstrates that the dorsal mid-insula contains a population of multimodal neurons that respond to both interoceptive and gustatory signals. Additionally, this gustatory adaptation by interoception was specific to the sweet tastant (0.6M sucrose) and did not significantly adapt the response to the neutral tastant (distilled water) (Table 4; not pictured). The specificity of this interoceptive adaptation effect to energy-rich gustatory stimuli suggests that these multimodal neurons may be involved in the homeostatic maintenance of energy intake.