AEP(聴覚性誘発電位)および脳波へのラベンダーおよびペパーミントの匂いの効果

The effects of odors (Lavender and Peppermint) on AEP (Auditory Evoked Potential) were studied with 15 healthy male subjects aged 22~39 y. o. (mean : 29.1 ± 4.8 y. o.). EEGs containing AEPs evoked by click stimuli once every 5 seconds were derived from the two derivations (3 ch : Cz→A1 +2, 6 ch : Cz→T5) , and recorded into magnetic tape. Reproducing the tape, AEPs with 1024 msec of analysis time were obtained by averaging 100 responses, and EEGs were subjected to the frequency analysis. In the experimental session, EEGs containing AEPs were recorded before, during and 15 and 30 minutes after the inhalation of odors of Lavender and Peppermint. Consecutive changes of group mean AEP were studied. Indivisual AEPs were subjected to the component analysis, and to the statistical assessment together with EEG. The following results were obtained.
1. Subjective assessment for the intensity and pleasantness of odors was not only so much different between Lavender and Peppermint, but close similar among the subjects.
2. During and after the inhalation of Lavender, latencies of the middle latency AEP including P2 latency, and latencies of long latency components (P6~) significantly or not significantly increased. Peak-to-peak amplitudes including P2-N2 of the middle latecy AEP significantly or not significantly decreased. During and after the inhalation of the odor of Peppermint, latencies of the middle latency AEP including P2 latency decreased but not significant, and peak-to-peak amplitudes including P2-N2 significantly or not significantly increased. Amplitudes of long latency component (P6~) did not change significantly. In conclusion, sedative effect of Lavender and a kind of stimulating effect of Peppermint on the middle latecy component were confirmed by AEP.
3. From the changes of P2, which derived from the brainstem reticular formation, it was said that Lavender inhibited, and Peppermint activated the reticular formation. Increased latencies of the long latency component of AEP during and after Lavender indicated the secondary inhibition of cortex succeeding to inhibition of the brainstem reticular formation.
4. Although the mechanism of olfactory system is not clarified, the odors of Lavender and Peppermint were might be differentiated in olfactory systems below neocortical olfactory area, and act on the reticular formation respectively inhibitorily or excitedly through the medial forebrain bundle.
5. It has been generally said that olfactory stimuli activate the CNS through the brainstem reticular formation, but inhibitory effect of Lavender similar to that of minor traquilizer, besides activating effect of Peppermint was verified for the first time by AEP.