CENTRAL PROCESSING OF ODOR CONCENTRATION IS A TEMPORAL PHENOMENON AS REVEALED BY CHEMOSENSORY EVENT-RELATED POTENTIALS (CSERP)

Chemosensory event-related potentials (CSERP) can be used to examine c entral nervous odor processing. An important question for understandin g odor perception is how different concentrations are processed. In th e present study two odors were chosen which activate either the olfact ory (linalool) or the trigeminal (menthol) system. Both odors were pre sented to 11 subjects in four different concentrations. Four subjects had to attend actively to the odors while the others perceived the odo rs under passive attention. The results showed that increased concentr ations of the olfactory stimulus resulted in shorter latencies of the N1 component but did not affect the amplitudes of the CSERP. However, the amplitudes of the stimulus dependent, exogenous components (N1, P2 ) increased with higher concentrations of the trigeminal stimulus. The amplitude of the late positive complex, which reflects endogenous pro cesses, was usually larger when the odorous stimuli had to be attended to actively. its concluded that olfactory intensity coding results in a qualitatively different but not in a stronger neuronal response of the human brain.