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Handedness, motor skills and maturation of the corticospinal tract in the adolescent brain
Version of Record online: 23 FEB 2009
Copyright © 2009 Wiley-Liss, Inc.
Human Brain Mapping
Volume 30, Issue 10, pages 3151–3162, October 2009
How to Cite
Hervé, P.-Y., Leonard, G., Perron, M., Pike, B., Pitiot, A., Richer, L., Veillette, S., Pausova, Z. and Paus, T. (2009), Handedness, motor skills and maturation of the corticospinal tract in the adolescent brain. Hum. Brain Mapp., 30: 3151–3162. doi: 10.1002/hbm.20734
- Issue online: 11 SEP 2009
- Version of Record online: 23 FEB 2009
- Manuscript Accepted: 18 DEC 2008
- Manuscript Received: 5 NOV 2008
- Canadian Institutes of Health Research
- Heart and Stroke Foundation of Quebec
- Canadian Foundation for Innovation
- pyramidal tracts;
- internal capsule;
- sex differences;
- functional laterality;
- myelin sheath;
- magnetic resonance imaging;
- postnatal development
With anatomical magnetic resonance imaging, the signal intensity of the corticospinal tract (CST) at the level of the internal capsule is often paradoxically similar to that of grey matter. As shown previously in histological studies, this is likely due to the presence of very large axons. We measured the apparent grey-matter density (aGMd) of the putative CST (pCST) in a large cohort of adolescents (n = 409, aged 12–18 years). We tested the following hypotheses: (1) The aGMd in the pCST shows a hemispheric asymmetry that is, in turn, related to hand preference; (2) the maturation of the CST during adolescence differs between both sexes, due to the influence of testosterone; (3) variations in aGMd in the pCST reflect inter-individual differences in manual skills. We confirmed the first two predictions. Thus, we found a strong left > right hemispheric asymmetry in aGMd that was, on average, less marked in the 40 left-handed subjects. Apparent GMd in the pCST increased with age in adolescent males but not females, and this was particularly related to rising plasma levels of testosterone in male adolescents. This finding is compatible with the idea that testosterone influences axonal calibre rather than myelination. The third prediction, namely that of a relationship between age-related changes in manual skills and maturation of the pCST, was not confirmed. We conclude that the leftward asymmetry of the pCST may reflect an early established asymmetry in the number of large corticomotoneuronal fibres in the pCST. Hum Brain Mapp, 2009. © 2009 Wiley-Liss, Inc.