The experience of pleasure is an important part of healthy life. The ability to experience pleasure, to certain extent, will be probed by different modalities of our sensation. Olfaction, in particular, has its own unique advantages over the other sensory modalities to probe our hedonic system. However, the neural mechanism underlying the olfactory hedonic processing is still not clearly known.  

Drs.ZUO Lai-quan and CHAN Raymond from the Institute of Psychology, have conducted meta-analysis to systematically review and examine olfactory hedonic processing in healthy volunteers. In particular, they specifically examined the studies using the whole brain voxel-based analyses of olfactory hedonic processing. Moreover, they further examined whether there would be hemispheric specialization of olfactory hedonic judgment when people were asked to judge the smell during scanning or just involved only passive smelling during scanning.  

Their findings suggest there is a core olfactory hedonic processing network that involves mainly the orbitofrontal regions, the parahippocampal gryus, and some other subcortical regions such as the lentiform nuclueus and globus pallidus. More interestingly, they also show there is a hemispheric specialization of olfactory hedonic judgment in our brain. The right hemisphere is predominant in performing the explicit odor hedonic judgment. Taken together, these results clarify the different neural mechanism for explicit (active) and passive olfactory hedonic judgment and highlight the important role of orbitofrontal cortex in olfactory hedonic judgment. These findings have important implications for our understanding of anhedonia observed in neuropsychiatric disorders such as schizophrenia, major depressive disorder and dementia.  

This study was supported by the Strategic Priority Research Program (B) of the Chinese Academy of Sciences, the National Natural Science Fund China, the Beijing Training Project for the Leading Talents in S & T, and the CAS/SAFEA International Partnership Program for Creative Research Teams. 

The paper is now published online in Neuropsychology.