Diffuse axonal injury (DAI) secondary to traumatic brain injury (TBI) contributes to long-term functional morbidity. The corpus callosum (CC) is particularly vulnerable to this type of injury. Magnetic resonance spectroscopy (MRS) was used to characterize the metabolic status of two CC regions of interest (ROIs) (anterior and posterior), and their structural (diffusion tensor imaging; DTI) and neurobehavioral (neurocognitive functioning, bimanual coordination, and interhemispheric transfer time [IHTT]) correlates. Two groups of moderate=severe TBI patients (ages 12-18 years) were studied: post-acute (5 months post-injury; n ¼ 10), and chronic (14.7 months post-injury; n ¼ 8), in addition to 10 age-matched healthy controls. Creatine (energy metabolism) did not differ between groups across both ROIs and time points. In the TBI group, choline (membrane degeneration=in-inflammation) was elevated for both ROIs at the post-acute but not chronic period. N-acetyl aspartate (NAA) (neuronal=axonal integrity) was reduced initially for both ROIs, with partial normalization at the chronic time point. Posterior, not anterior, NAA was positively correlated with DTI fractional anisotropy (FA) (r ¼ 0.88), and most domains of neurocognition (r range 0.22-0.65), and negatively correlated with IHTT (r ¼ À0.89). Inverse corerlations were noted between creatine and posterior FA (r ¼ À0.76), neurocognition (r range À0.22 to À0.71), and IHTT (r ¼ 0.76). Multimodal studies at distinct time points in specific brain structures are necessary to delineate the course of the degenerative and reparative processes following TBI, which allows for preliminary hypotheses about the nature and course of the neural mechanisms of subsequent functional morbidity. This will help guide the future development of targeted therapeutic agents.

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Reasons for code-switching in young children range from the linguistic (single-word borrowings that appear to be translation equivalents or to fill gaps in lexical knowledge) to more complex sociolinguistic and sociocognitive factors, such as desiring affiliative interactions. We looked at patterns of code-switching in narratives derived from prompted story stems from 97 Mexican-heritage children between 54-67 months. Code-switches were categorized into two broad categories: code-mixings, or single-word borrowings, and code-changes that appeared to have a sociopragmatic purpose. Most code-switches took the form of single-word borrowings. Some, however, were sociopragmatic in nature, such as the child code-switching to try to gain the interviewer's attention or to change speaking roles, suggesting these young children have the facility to use their two languages strategically for both linguistic and nonlinguistic purposes from a very early age.

Expanding on Babikian and Asarnow's (2009) meta-analytic study examining neurocognitive domains, this current meta-analysis examined academic and language outcomes at different time points post-traumatic brain injury (TBI) in children and adolescents. Although children with mild TBI exhibited no significant deficits, studies indicate that children with moderate and severe TBI exhibit persistent deficits. In children with moderate TBI, academic skills were impaired both postacutely and chronically, although there were no deficits in language skills at any time point. Children with severe TBI showed the most impairment, with deficits in all measured areas, and partial recovery in some domains over time. The results of this meta-analysis may have important implications for school reentry, academic placement, and identifying children who require special services in school.