期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2021
卷号：118
期号：42
DOI：10.1073/pnas.2101209118
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Significance
Whether an odor's perceived valence induces an approach response or triggers avoidance is critical for survival, and yet little is known about the neural mechanisms supporting this decision. Using electrophysiological measures from the human olfactory bulb (OB), the first processing stage of the olfactory system, and measures of full-body movement, we provide evidence that this process is initiated in the human OB. We demonstrate that odor valence is associated with both gamma and beta activity in the OB. Furthermore, we show that unpleasant odors have privileged temporal OB access, as indicated by early beta activity that is linked to a preparatory neural motor response in the motor cortex, which, in turn, is associated behaviorally with a fast full-body avoidance response.
Determining the valence of an odor to guide rapid approach–avoidance behavior is thought to be one of the core tasks of the olfactory system, and yet little is known of the initial neural mechanisms supporting this process or of its subsequent behavioral manifestation in humans. In two experiments, we measured the functional processing of odor valence perception in the human olfactory bulb (OB)—the first processing stage of the olfactory system—using a noninvasive method as well as assessed the subsequent motor avoidance response. We demonstrate that odor valence perception is associated with both gamma and beta activity in the human OB. Moreover, we show that negative, but not positive, odors initiate an early beta response in the OB, a response that is linked to a preparatory neural motor response in the motor cortex. Finally, in a separate experiment, we show that negative odors trigger a full-body motor avoidance response, manifested as a rapid leaning away from the odor, within the time period predicted by the OB results. Taken together, these results demonstrate that the human OB processes odor valence in a sequential manner in both the gamma and beta frequency bands and suggest that rapid processing of unpleasant odors in the OB might underlie rapid approach–avoidance decisions.
