Researchers led by Professor Wen Li made use of functional MRI to analyze the brain activity of 12 participants after they were shown images that were designed to induce anxiety as they smelled familiar, neutral odors.
They were then asked to rate the different smells before and after being shown the images. The researchers found that majority of the participants displayed a more negative response to smells that they had marked as neutral before being shown the images.
"After anxiety induction, neutral smells become clearly negative. In typical odor processing, it is usually just the olfactory system that gets activated. But when a person becomes anxious, the emotional system becomes part of the olfactory processing stream", Professor Li said.