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In vivo evidence for post-adolescent brain maturation in frontal
and striatal regions
Source: Nature Neuroscience 1999 Oct;2(10):859-861.
Author: Sowell ER, Thompson PM, Holmes CJ, Jernigan TL, Toga AW.
PubMed ID: 10491602
Abstract:
We spatially and temporally mapped brain maturation between adolescence and young adulthood using a whole-brain, voxel-by-voxel statistical analysis of high-resolution structural magnetic resonance images (MRI). The pattern of brain maturation during these years was distinct from earlier development, and was localized to large regions of dorsal, medial and orbital frontal cortex and lenticular nuclei, with relatively little change in any other location. This spatial and temporal pattern agrees with convergent findings from post-mortem studies of brain development and the continued development over this age range of cognitive functions attributed to frontal structures. OBJECTIVE: Here we assessed postadolescent brain maturation by studying a group of normal, young adults, 23-30 years of age, as well as 12-16 year olds studies previously. We anticipated that the pattern of brain maturation between adolescence and adulthood wuld differ from that observed between childhood and adolescence. Specifically, we anticipated more maturational changes in the frontal lobes than in other cortical regions because, in addition to the post-mortem findings of delayed frontal maturation, converging evidence from electrophysiological and cerebral glucose-metabolism studies reveals relatively late frontal maturation. METHODS: High-resolution MRI brain images were acquired for each subject in the same magnet. First image volumes were resliced into a standard orientation, making it easier to define cerebral and non-cerebral regions. 3D digital filtering was applied to each volume to reduce signal-value variability due to radio-frequency inhomogeneity artifacts. Each image set was subjected to semiautomated tissue segmentation to classify voxels as gray matter, white matter or CSF based on signal value. Nonbrain tissue and cerebellar structures were subtacted from each image. For statistical parametric mapping analyses, each subject's brain volume was scaled into a standard space using an automated 12-parameter linear transformation. RESULTS: The SPM of differences between teens and adults observed here contrasted with the SPM of differences between childhood and adolescence. Specifically, parietal, temporal and occipital lobes showed little maturational changes, as predicted, dorsal, medial and lateral regions of the frontal lobes sowed large group differences. In regions of frontal cortex, we observed reduction in gray matter between adolescence and adulthood, probably reflecting increased myelination in peripheral regions of the cortex that may improve cognitive processing in adulthood.
Source: Nature Neuroscience 1999 Oct;2(10):859-861.
Author: Sowell ER, Thompson PM, Holmes CJ, Jernigan TL, Toga AW.
PubMed ID: 10491602
Abstract:
We spatially and temporally mapped brain maturation between adolescence and young adulthood using a whole-brain, voxel-by-voxel statistical analysis of high-resolution structural magnetic resonance images (MRI). The pattern of brain maturation during these years was distinct from earlier development, and was localized to large regions of dorsal, medial and orbital frontal cortex and lenticular nuclei, with relatively little change in any other location. This spatial and temporal pattern agrees with convergent findings from post-mortem studies of brain development and the continued development over this age range of cognitive functions attributed to frontal structures. OBJECTIVE: Here we assessed postadolescent brain maturation by studying a group of normal, young adults, 23-30 years of age, as well as 12-16 year olds studies previously. We anticipated that the pattern of brain maturation between adolescence and adulthood wuld differ from that observed between childhood and adolescence. Specifically, we anticipated more maturational changes in the frontal lobes than in other cortical regions because, in addition to the post-mortem findings of delayed frontal maturation, converging evidence from electrophysiological and cerebral glucose-metabolism studies reveals relatively late frontal maturation. METHODS: High-resolution MRI brain images were acquired for each subject in the same magnet. First image volumes were resliced into a standard orientation, making it easier to define cerebral and non-cerebral regions. 3D digital filtering was applied to each volume to reduce signal-value variability due to radio-frequency inhomogeneity artifacts. Each image set was subjected to semiautomated tissue segmentation to classify voxels as gray matter, white matter or CSF based on signal value. Nonbrain tissue and cerebellar structures were subtacted from each image. For statistical parametric mapping analyses, each subject's brain volume was scaled into a standard space using an automated 12-parameter linear transformation. RESULTS: The SPM of differences between teens and adults observed here contrasted with the SPM of differences between childhood and adolescence. Specifically, parietal, temporal and occipital lobes showed little maturational changes, as predicted, dorsal, medial and lateral regions of the frontal lobes sowed large group differences. In regions of frontal cortex, we observed reduction in gray matter between adolescence and adulthood, probably reflecting increased myelination in peripheral regions of the cortex that may improve cognitive processing in adulthood.