It's enough to make you sweat
Scientists have long known that animals use scent to communicate. But how much does the human sense of smell complement the more powerful senses of sight and hearing?
To find out, Denise Chen, an assistant professor of psychology, used functional magnetic resonance imaging (fMRI) to look at how the brains of female volunteers processed and encoded the smell of sexual sweat from men. Nineteen healthy female subjects inhaled olfactory stimuli from four sources, one of which was sweat gathered from sexually aroused males. The study is the first fMRI study of human social chemosignals.
The results of the experiment indicated that the brain recognizes chemosensory communication, including human sexual sweat, and that several areas of the brain are involved in processing the emotional value of the olfactory information. These include the right fusiform region, the right orbitofrontal cortex and the right hypothalamus.
“Our results imply that the chemosensory information from natural human sexual sweat is encoded more holistically in the brain rather than specifically for its sexual quality.”
— Denise Chen
“With the exception of the hypothalamus, neither the orbitofrontal cortex nor the fusiform region is considered to be associated with sexual motivation and behavior,” Chen said. “Our results imply that the chemosensory information from natural human sexual sweat is encoded more holistically in the brain rather than specifically for its sexual quality.”
Humans are evolved to respond to salient socioemotional information, and just as distinctive neural mechanisms underlie the processing of emotions in facial and vocal expressions, so, too, do mechanisms for human social chemosignals.
The research, co-authored by Chen and Wen Zhou, graduate student in the Department of Psychology, was supported in part by the National Institutes of Health and published in the Journal of Neuroscience.