Olfactory lateralization in humans: a review

In the field of human perception, the chemical senses (taste and smell) have received little attention from neuroscience research when compared with auditory, visual al rd tactile senses. In the case of olfaction, it would appear th(tr the publications over the last few years have been trying to overcome this lack of research. Many investigations have been carried out on lateralization,,mainly in relation to specific pathologies (i.e., epilepsy split-brain, lobotomy, etc.), while there have been Sew studies of healthy subjects. The results are often contradictory due particularly to special features of the olfactory system. However consensus is emerging concerning, first, the fact that if both hemispheres are involved in rile olfactory process, it is probable that one is more dominant than the other (many studies have revealed a greater impact on the right hemisphere in the treatment of olfactory information, but the dominance has not been clearly established). Second the simple detection process would appear not to be lateralized whereas the higher-order olfactory tasks which involve memory processes and lexical aspects could be. The exact conditions governing lateralization still require more clarification by systematically taking into consideration the characteristics of the individual subjects, as well as those of the odorant stimuli and the test conditions. Finally, currently available techniques used irt neurosciences and particularly cerebral imagery will contribute to a better understanding of the complexity of cerebral asymmetry in olfaction. (C) 1999 Editions scientifiques et medicales Elsevier SAS.