Abstract
Olfactory perception and related emotions are largely dependent on inspiration. Recently, we performed simultaneous respiration and electroencephalographic (EEG) recordings during odor stimulation. We sought to identify changes in respiratory pattern, inspiratory phase-locked alpha oscillation (I-α) and location of dipoles estimated from the potentials. EEG dipole tracing identified the location of dipoles from the I-α in the entorhinal cortex, hippocampus, amygdala, premotor area and orbitofrontal cortex. These results were obtained without habituation of odors, therefore these areas could be related to the odor recognition, odor induced emotion, and odor discrimination. Habituation in olfaction apperars to be caused by not only the olfactory receptor level but also olfactory central structures. In this study, we compared the respiratory pattern, I-α, and dipole localizations during non habituation period with those during habituation of odors. Habituation of odor caused to return to the normal respiratory pattern, but I-α was still observed, however, power spectra of frontal area were decreased compared with I-α during non habituation. From averaged potentials with habituation, dipoles were estimated in the entorhinal cortex, hippocampus and amygdala, and not observed in the orbitofrontal cortex. [J Physiol Sci. 2007;57 Suppl:S70]
