From Face to Cortex : Individual Ratings and Neural Activation for Dose-Dependent Chemosensory and Somatosensory Stimuli

This experimental study aimed to fill the existing knowledge gap of dose-dependent neural activation for the processing of chemosensory stimuli. Therefore, the present looked at cortical brain activity with the help of a functional near-infrared spectroscopy (fNIRS) cap in order to find brain areas responsible. The subjective intensity ratings for stimuli of different intensity for both somatosensation and chemosensation was also recorded. Healthy participants with no sensory anomalities in chemo- and/or somatosensation, repeatedly rated four chemosensory (n-butanol dilutions) and four somatosensory-pressure stimuli (3-D printed device on masseter muscle) using the Borg CR-100 scale. Ratings for both chemosensory and somatosensory stimuli increase with the intensity and the two modalities correlate with each other. Furthermore, bilateral activity in middle temporal gyrus linked to the processing of chemosensory intensity.