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BRAIN SEX DIFFERENCES IN THE THALAMUS, CORPUS CALLOSUM AND CINGULUM

Posted by Annapaola Prestia Laboratory of Epidemiology Neuroimaging and Telemedicine, IRCCS Centro San Giovanni di Dio FBF, The National Centre for Research and Care of Alzheimer’s and Mental Diseases, Brescia, Italy. January 2011

The aim of the present study was to investigate microstructural white matter differences in the brain of male and female subjects using an unbiased hypothesis. Fifty right-handed healthy subjects, 25 males (mean age 31.8 ± 8.6 years) and 25 females (mean age 31.1 ± 10.6 years) were included in the study. Microstructural brain tissue integrity was assessed using Diffusion Tensor Imaging measures: fractional anisotropy (FA), axial diffusivity (AD) and radial diffusivity (RD).
Results displayed regional microstructural white matter sex differences in the thalamus, with men showing significantly higher FA values in this region (p < 0.0001). Additionally, FA was increased in males as compared to females in parts of the corpus callosum and cingulum as well as in the capsula extrema and midbrain. This study has showed widespread differences in thalamic microstructure that have not been described previously. Additionally, the present study confirmed earlier DTI studies focusing on sexual dimorphism in the corpus callosum and cingulum. All changes appear to be based on differences in myelination. The sex differences in thalamic microstructure call for further studies on the underlying cause and the behavioural correlates of this sexual dimorphism.