Previous investigations have suggested that low, undetectable concentrations of odor chemicals alter central nervous system (CNS) activity. Since there can be no odor-free environment, room air also may alter CNS activity. To examine this hypothesis, EEG data were recorded from 20 subjects while they inhaled room air through the mouth or the nose. Results of the experiment indicated that EEG alpha activity in the left hemisphere was reduced for individuals inhaling through the nose, and that EEG beta activity showed greater spatial diversity during nose inhalations. These results demonstrate that room air passing through the nose has a desynchroniz-ing effect upon the EEG and may contain odor information not available through mouth inhalation. These results further substantiate the hypothesis that undetected odors markedly alter ongoing CNS activity.
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