gms | German Medical Science

Introduction: Two optical isomer of rose oxide (R +, R -), which are psychophysically indistinguishable odour enantiomers were used to show differences in electrophysiological response to olfactory information on a central and peripheral level in humans.

Methods: Nineteen subjects (14 females, mean age: 25.37, SD: 3.47) participated in the study. A three alternative forced choice test was applied to demonstrate indistinguishability of the two enantiomers. The peripheral electrophysiological response to odours was investigated by means of electro-olfactogram (EOG) recordings representing activity of peripheral olfactory receptor neurons. Central response was studied using olfactory event-related potentials (OERP) presenting early central-nervous processing of olfactory information.

Results: There was no significant difference from chance level (p = 0.41) in discriminating the odour enantiomers. OERP recordings could be recorded from 18/19 and EOG recording from 14/19 participants. A significantly higher N1 (p = 0.039) and p1N1 (p = 0.032) amplitude and a significantly higher latency lN1 (p = 0.005) and lp1 (p = 0.024) could be recorded in response to R + in the EOG. However, no such differences in amplitude or latency (ps > 0.05) could be shown in the OERP.

Conclusion: The current results show that two psychophysically indistinguishable odour enantiomers do not show any electrophysiological differences in early central-nervous response. However, a significant difference in EOG response to the two odours at the level of the olfactory epithelium indicates a more detailed processing of odours in the periphery. This processing seems not only to depend on the organic compounds of the odour but also on the spatial arrangement of their atoms as seen in these stereoisomers.

Unterstützt durch: Dresden Fellowship Programm unterstützte Poletti SC

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