Maturation of brain white matter pathways is an important factor in cognitive, behavioral, emotional and motor development during childhood and adolescence. In this study, we investigate white matter maturation as reflected by changes in anisotropy and white matter density with age. Thirty-four children and adolescents aged 6-19 years received diffusion-weighted magnetic resonance imaging scans. Among these, 30 children and adolescents also received high-resolution T1-weighed anatomical scans. A linear regression model was used to correlate fractional anisotropy (FA) values with age on a voxel-by-voxel basis. Within the regions that showed significant FA changes with age, a post hoc analysis was performed to investigate white matter density changes. With increasing age, FA values increased in prefrontal regions, in the internal capsule as well as in basal ganglia and thalamic pathways, the ventral visual pathways, and the corpus callosum. The posterior limb of the internal capsule, intrathalamic connections, and the corpus callosum showed the most significant overlaps between white matter density and FA changes with age. This study demonstrates that during childhood and adolescence, white matter anisotropy changes in brain regions that are important for attention, motor skills, cognitive ability, and memory. This typical developmental trajectory may be altered in individuals with disorders of development, cognition and behavior.

Williams syndrome (WS) is a neurogenetic-neurodevelopmental disorder characterized by a highly variable and enigmatic profile of cognitive and behavioral features. Relative to overall intellect, affected individuals demonstrate disproportionately severe visual-spatial deficits and enhanced emotionality and face processing. In this study, high-resolution magnetic resonance imaging data were collected from 43 individuals with WS and 40 age-and gender-matched healthy controls. Given the distinct cognitive-behavioral dissociations associated with this disorder, we hypothesized that neuroanatomical integrity in WS would be diminished most in regions comprising the visual-spatial system and most "preserved" or even augmented in regions involved in emotion and face processing. Both volumetric analysis and voxel-based morphometry were used to provide convergent approaches for detecting the hypothesized WS neuroanatomical profile. After adjusting for overall brain volume, participants with WS showed reduced thalamic and occipital lobe gray matter volumes and reduced gray matter density in subcortical and cortical regions comprising the human visual-spatial system compared with controls. The WS group also showed disproportionate increases in volume and gray matter density in several areas known to participate in emotion and face processing, including the amygdala, orbital and medial prefrontal cortices, anterior cingulate, insular cortex, and superior temporal gyrus. These findings point to specific neuroanatomical correlates for the unique topography of cognitive and behavioral features associated with this disorder.

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Traumatic stress may impact development of brain regions important for emotion processing. Timing of activation may be altered in youth with PTSS.

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Previous studies have revealed altered structural development of the frontal lobes and prefrontal cortex (PFC) in children with symptoms of posttraumatic stress disorder (PTSD). This study is the first to provide a detailed structural analysis of the PFC in children with and without PTSD symptoms. We compared gray and white matter volume in four subregions of the PFC between said groups, then explored whether volume was associated with PTSD symptom severity and functional impairment. PFC measurements were extracted from magnetic resonance imaging (MRI) data from a sample of 23 children (ages 7-14) with a history of trauma and symptoms of PTSD, who had undergone assessment for PTSD symptoms and functional impairment using the Child and Adolescent version of the Clinician-Administered PTSD Scale (CAPS-CA). These measurements were compared to data from an age-equivalent control group of 24 healthy children. Children with PTSD symptoms showed a significantly larger volume of gray matter in the delineated middle-inferior and ventral regions of the PFC than did control children. Decreased volume of gray matter in the dorsal PFC correlated with increased functional impairment scores. Results indicate that increased volume of the middle-inferior and ventral PFC may be associated with trauma and PTSD symptoms in children. Furthermore, the neuroanatomy of the dorsal PFC may influence the degree of functional impairment experienced by children with PTSD symptoms.

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