We recorded EEG in adult volunteers in the course of perception of smells of plant essential oils under conditions of directed attention. It was found that perception of olfactory information, even in the case of mild intensity of the smells inducing no aversive effects, correlates with noticeable changes in the EEG characteristics mostly typical of the reaction of nonspecific EEG activation induced by sensory stimulation and manifested in a decrease in the spectral power, SP, of low-frequency EEG components (6-10 Hz)). In addition, the SP of relatively high-frequency EEG components (11-25 Hz) increased; this effect was most pronounced in the occipital regions of the neocortex. Perception of the smells of essential oils was also accompanied by increases in the coherence of EEG oscillations, most intense in the β2 range (20-25 Hz). Such modifications were maximum in the left temporal/parietal region; this is interpreted as an indication of the special role of these cortical areas in the processes of interaction between the neocortical part of the olfactory analyzer and the respective structures of other analyzer systems. It is hypothesized that such interaction is necessary for the formation of a semantic image of the analyzed stimuli.

We studied changes in human EEGs related to presentation of olfactory stimuli (smells of essential oils) and dependence of such rearrangements on the level of extroversion/introversion typical of the tested subject. It was shown that this feature of personality noticeably influences the pattern of odorant-induced changes in EEG. Persons with a predominance of introversion were characterized by higher levels of nonspecific activation of the brain related to perception of olfactory stimuli, which was manifested in a decrease in the power of lowfrequency EEG components in the parietal, occipital, and temporal cerebral cortices. The pattern of the rise in coherence level of high-frequency spectrum range oscillations directed toward caudal leads is considered a manifestation of intensification of the intrinsic associative processes. In individuals with a predominance of extroversion, we observed, on the whole, smaller levels of nonspecific cerebral activation upon the action of olfactory stimulation. The fronto-parietal pattern of spatial EEG synchronization is indicative of the development of sensory-analytical processes related to perception of external information. In general, our data agree with the interpretation of such a psychological parameter as extroversion/introversion.