14 DAY TRIAL // The field of human olfaction is still an area of medicine that can be thought of as a small child. At this point, very few studies have been done on how the olfactory sensation is picked up, integrated, and then processed within the brain. While the basic mechanisms are known, more advanced features are still a mystery to science. Recently, a new study has shown that the brain processes stimuli coming in from both nostrils alternately, and not simultaneously, as it could have been expected.
In recent experiments, scientists from the Rice University asked 12 test participants to sample smells from two bottles containing distinctively different odors – one of roses (phenyl ethyl alcohol), and one similar to that of a pen marker (n-butanol). The little bottles were outfitted with special dispensers at the top, so that test subjects could place each one in a different nostril. The 12 volunteers were then asked to carry out 20 rounds of sampling. For each one, they explained how they felt the two smells.
In all of the rounds, all of the volunteers went through a strange process. They reported that they could not feel both of the smells at their full intensity at the same time. Rather, each of them took precedence over the other for a little while, after which the patterns were reversed. When analyzing this trend over the entire group, the research team was unable to find any statistically relevant patterns, neither in separate individuals, nor in the group as a whole.
“Instead of perceiving a constant mixture of the two smells, they perceive one of the smells, followed by the other, in an alternating fashion, as if the nostrils were competing with one another. Although both smells are equally present, the brain attends to predominantly one of them at a time,” RU Assistant Professor of Psychology Denise Chen, a co-author of a new paper detailing the finds, published in the latest online issue of the journal Current Biology, explains.
“The binaral rivalry involves adaptations at the peripheral sensory neurons and in the cortex. Our work sets the stage for future studies of this phenomenon so we can learn more about the mechanisms by which we perceive smells. Our discovery opens up new avenues to explore the workings of the olfactory system and olfactory awareness,” she adds. The study is also scheduled to appear in the September 29th print issue of the same publication.