Olfaction and hemispheric asymmetry: unilateral stimulation and bilateral electrodermal recordings

The study of hemispheric asymmetry in olfaction in human subjects has given rise to many publications, but the findings have often been contradictory. This study used bilateral electrodermal activity recordings with unilateral stimulation as a measure of functional hemispheric asymmetry. A specific odorant (lavender) was used by monorhinic (single nostril) stimulation on 30 dextral subjects (20 females and 10 males). Intraindividually, the results showed no difference between the two nostrils, but all subjects exhibited a constant direction of electrodermal asymmetry: 20 subjects systematically showed a greater response amplitude for the right hand and 10 subjects systematically showed a greater response amplitude for the left hand, whatever hemisphere stimulated.