Testosterone affects language areas of the adult human brain |
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Authors: | Andreas Hahn Georg S. Kranz Ronald Sladky Ulrike Kaufmann Sebastian Ganger Allan Hummer Rene Seiger Marie Spies Thomas Vanicek Dietmar Winkler Siegfried Kasper Christian Windischberger Dick F. Swaab Rupert Lanzenberger |
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Affiliation: | 1. Department of Psychiatry and Psychotherapy, Medical University of Vienna, Austria;2. MR Center of Excellence, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Austria;3. Department of Obstetrics and Gynecology, Medical University of Vienna, Austria;4. Netherlands Institute for Neuroscience, Institute of the Royal Netherlands Academy of Arts and Sciences, Amsterdam, the Netherlands |
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Abstract: | Although the sex steroid hormone testosterone is integrally involved in the development of language processing, ethical considerations mostly limit investigations to single hormone administrations. To circumvent this issue we assessed the influence of continuous high‐dose hormone application in adult female‐to‐male transsexuals. Subjects underwent magnetic resonance imaging before and after 4 weeks of testosterone treatment, with each scan including structural, diffusion weighted and functional imaging. Voxel‐based morphometry analysis showed decreased gray matter volume with increasing levels of bioavailable testosterone exclusively in Broca's and Wernicke's areas. Particularly, this may link known sex differences in language performance to the influence of testosterone on relevant brain regions. Using probabilistic tractography, we further observed that longitudinal changes in testosterone negatively predicted changes in mean diffusivity of the corresponding structural connection passing through the extreme capsule. Considering a related increase in myelin staining in rodents, this potentially reflects a strengthening of the fiber tract particularly involved in language comprehension. Finally, functional images at resting‐state were evaluated, showing increased functional connectivity between the two brain regions with increasing testosterone levels. These findings suggest testosterone‐dependent neuroplastic adaptations in adulthood within language‐specific brain regions and connections. Importantly, deteriorations in gray matter volume seem to be compensated by enhancement of corresponding structural and functional connectivity. Hum Brain Mapp 37:1738–1748, 2016. © 2016 Wiley Periodicals, Inc . |
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Keywords: | testosterone language neuroplasticity voxel‐based morphometry probabilistic tractography functional connectivity |
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