Psychophysiological effect of odor

Techniques to measure the activity of the taste and odor molecules at the olfactory epithelium, taste bud, and brain response levels are now being used to determine and measure the actual transduction of the chemical information to the brain waves. We studied a number of methods of measuring brain wave responses to odorants and we settled on an electroencephalographic method of measuring the slow brain waves [> 13 Hz] at the frontal location on the scalp. This technique known as contingent negative variation (CNV) measures the early component [at 400 to 1000 ms] of the beta wave variation, which can be negative, positive, or neutral depending on the odorant being presented to the subject. This component is almost independent of the subject's psychological state, degree of arousal, or level of consciousness and is known as the external component. The experimental paradigm creates a reproducible result in which odorants may be classified as stimulating, sedating, or neutral. These psychophysiological effects of odors on man appear to offer a means to determine precognitive responses directly related to the effect of the chemical messenger. There does not appear to be any bias as to sex, national origin, or race. At this point in our research efforts, we do not see evidence that there is a bias related to age. It is proposed that some of the problems of classical sensory evaluation can be helped by the use of psychophysiological recording techniques, such as CNV, as a measurement of brain activity and response to flavor and aroma.