Application of functional near-infrared spectroscopy (fNIRS) for studying the influence of capsaicin stimulation on brain perception

Spicy taste have been utilized in the food industry as appetizers, stomachics, and beverages and in the health sector to alleviate high cholesterol and hypertension. However, an understanding of  neural mechanisms and cognitive processes associated with spicy diets remains limited due to the lack of instruments that directly monitoring the brain’s reaction to spicy sensations.  This study aimed to examine the neural responses of participants to oral capsaicin solutions through functional near-infrared spectroscopy and reveal distinct neural activation patterns associated with  spiciness induction and relief phases. Results showed that the perception of spiciness is a dynamic process, and significant differences in sensory intensity and emotion were observed between the phases. The prefrontal regions of the brain were activated during spicy flavor perception and presented clear lateralization effects.  Further spatial localization results indicated that the orbitofrontal, dorsolateral prefrontal, and ventral lateral prefrontal cortices were the main causes of difference in activation among the phases. In addition, correlational analyses indicated that spicy flavor perception activated cortical areas related to emotion and reward processing. Overall, this research enhances our understanding of the neural mechanisms underlying addiction to spicy food and may be useful in the development of food on the basis of consumers’ preferences and behavioral responses.