Sex Differences in the Olfactory System: a Functional MRI Study
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Olfactory dysfunction is an early marker of neurological disease and a common symptom in psychotic disorders. Previous anatomical and functional research suggests that sex effects may be crucial in the assessment of the olfactory system. Nonetheless, the neural mechanisms through which the factor sex impacts olfactory perception are still not well understood. In this context, we use fMRI to investigate sex differences in the passive processing of chemical stimuli, in order to obtain new neuroscientific data that may help improve the assessment of odor perception.
Thirty healthy subjects (17 women) were stimulated with mint and butanol (event-related design) in a 3.0-T MRI scanner. A one-sample t test analysis was performed in order to observe olfactory-related activations. Intergroup differences (women vs. men) and the influence of each aroma were analyzed using a 2 × 2 ANOVA and post hoc contrasts.
Men and women showed differential activity (males > females) in right superior/middle temporal areas, the right inferior frontal cortex, and the hypothalamus. Both groups showed a predominance of the right hemisphere for the processing of odors.
Functional differences between women and men in olfaction are not restricted to specific sensory areas and reflect a more general sex-dependent effect in multisensory integration processes.
Considering sex differences is essential in order to develop more specific and efficient strategies for the assessment and rehabilitation of the olfactory system and for the interpretation of the olfactory loss as an early biomarker of neurological and psychiatric diseases.
KeywordsOlfaction fMRI Odors Multisensory integration Assessment Neurodegenerative
The authors thank the participants and the technical staff at the 3T scanner facility of Fundación Reina Sofía-Centro de Investigación de Enfermedades Neurológicas for their collaboration in this study.
This work was supported by the Spanish Ministry of Economy and Competitiveness [TEC2012-39095-C03-01, DPI2015-68664-C4-2-R].
Compliance with Ethical Standards
Conflict of Interest
Helena Melero, Susana Borromeo, Alexandra Cristobal-Huerta, Eva Manzanedo, Guillermo Luna, Adolfo Toledano, and Juan Antonio Hernandez Tamames declare that they have no conflict of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
Written informed consent was obtained from all individual participants included in the study.
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