Effects of Passive Perception of Isoamyl Acetate Smell on the Resting-State EGG in Humans

We analyzed changes in the spectral powers of different EEG frequency ranges and levels of coherence of the respective oscillations under conditions of passive perception of the smell of isoamyl acetate (pear essence) by humans in the resting state. Depending on a subjective estimate of the smell of isoamyl acetate, its presence per se caused increases in the mean levels of coherence of high-frequency a-subrange oscillations in all tested persons, which can be indicative of intensification of internal mental activity and increase in readiness to react. In the tested persons estimating the used olfactory stimulus as negative, the coherence of α2- and β1-oscillations in the central cortical areas and in the frontal and occipital zones decreased. In the tested persons with the positive subjective estimate of the isoamyl acetate smell, the coherence increased also in the a1-subrange during the action of this olfactory stimulus. Therefore, we obtained indications that activation of the olfactory analyzer is capable of changing the functioning of neuronal networks of the human brain in the resting state, and the pattern of these alterations partly depends on a subjective hedonic estimate of one smell or another.