Cerebral White Matter Myelination and Relations to Age, Gender, and Cognition: A Selective Review

Abstract

White matter makes up about fifty percent of the human brain. Maturation of white matter accompanies biological development and undergoes the most dramatic changes during childhood and adolescence. Despite the advances in neuroimaging techniques, controversy concerning spatial, and temporal patterns of myelination, as well as the degree to which the microstructural characteristics of white matter can vary in a healthy brain as a function of age, gender and cognitive abilities still exists. In a selective review we describe methods of assessing myelination and evaluate effects of age and gender in nine major fiber tracts, highlighting their role in higher-order cognitive functions. Our findings suggests that myelination indices vary by age, fiber tract, and hemisphere. Effects of gender were also identified, although some attribute differences to methodological factors or social and learning opportunities. Findings point to further directions of research that will improve our understanding of the complex myelination-behavior relation across development that may have implications for educational and clinical practice.

White matter microstructure shows sex differences in late childhood: Evidence from 6,797 children

“…Commissural tracts connect the left and right hemispheres, and the fornix connects areas involved in memory (Buyanova & Arsalidou, 2021;Catani & Thiebaut de Schotten, 2008;Hagler et al, 2009). The corticospinal/pyramidal tract connects the motor cortex to the spinal cord, and the anterior thalamic radiation connects the thalamus with the frontal cortex (Buyanova & Arsalidou, 2021;Catani & Thiebaut de Schotten, 2008;Hagler et al, 2009).…”

“…With regard to the regional distribution of sex differences, differences were most pronounced in association and superior corticostriatal white matter tract ROIs. Association fibers connect distributed cortical regions within the same hemisphere, and corticostriatal tracts connect cortical areas across the brain with the striatum (Buyanova & Arsalidou, 2021;Hagler et al, 2009).…”

“…The impact of participant sex was the least notable in commissural and limbic (fornix) white matter tract ROIs, as well as sensorimotor (corticospinal/pyramidal tract) and thalamic (anterior thalamic radiation) projection tract ROIs. Commissural tracts connect the left and right hemispheres, and the fornix connects areas involved in memory (Buyanova & Arsalidou, 2021; Catani & Thiebaut de Schotten, 2008; Hagler et al, 2009). The corticospinal/pyramidal tract connects the motor cortex to the spinal cord, and the anterior thalamic radiation connects the thalamus with the frontal cortex (Buyanova & Arsalidou, 2021; Catani & Thiebaut de Schotten, 2008; Hagler et al, 2009).…”

“…With regard to the regional distribution of sex differences, differences were most pronounced in association and superior corticostriatal white matter tract ROIs. Association fibers connect distributed cortical regions within the same hemisphere, and corticostriatal tracts connect cortical areas across the brain with the striatum (Buyanova & Arsalidou, 2021; Hagler et al, 2009). The impact of participant sex was the least notable in commissural and limbic (fornix) white matter tract ROIs, as well as sensorimotor (corticospinal/pyramidal tract) and thalamic (anterior thalamic radiation) projection tract ROIs.…”

“…Commissural tracts connect the left and right hemispheres, and the fornix connects areas involved in memory (Buyanova & Arsalidou, 2021; Catani & Thiebaut de Schotten, 2008; Hagler et al, 2009). The corticospinal/pyramidal tract connects the motor cortex to the spinal cord, and the anterior thalamic radiation connects the thalamus with the frontal cortex (Buyanova & Arsalidou, 2021; Catani & Thiebaut de Schotten, 2008; Hagler et al, 2009). As association tracts generally exhibit more prolonged development than commissural and projection tracts, our results suggest that sex differences in late childhood may be most substantial in fibers with protracted developmental trajectories (Tamnes et al, 2018).…”