Neurological Responses to Scented Insects via Olfactory Stimulation: A Controlled fMRI Study

The link between the olfactory system and psychiatric disorders is well documented; however, the neurological effects of insect-derived scents on human brain function remain unexplored. This study examined the neurological response to scented insects using functional magnetic resonance imaging (fMRI) to evaluate their potential as a novel animal-assisted intervention (AAI) for mental health. In this controlled, crossover trial, the olfactory effects of scented insects (Poecilocoris splendidulus Esaki) were compared with a control scent (alcohol) in 29 psychologically healthy adults. Brain activation differences were assessed using paired t-tests with false discovery rate correction, followed by multiple regression analyses incorporating psychometric assessments. Compared with the control scent, the insect scent elicited greater activation across sensory, emotional, and memory-related brain networks, including the thalamus, insula, hippocampus, and prefrontal cortex (p < 0.05). Furthermore, individual psychometric variations influenced these responses: higher depressive symptoms were associated with reduced activation in the anterior cingulate cortex, while elevated stress and anxiety correlated with heightened activity in the hippocampus and inferior frontal gyrus. These findings suggest that insect-derived scents induce distinct neurological responses linked to emotional processing, supporting their potential application in therapeutic interventions for mental health.