No abstract

The ability to carry out two tasks simultaneously, dual tasking, is specifically impaired after traumatic brain injury (TBI). The aim of the present study was to investigate the neuronal correlates to this increased dual cost in chronic severe TBI patients (n = 10) compared to healthy controls (n = 11) using functional magnetic resonance imaging (fMRI) at 3 Tesla (T). The tasks were a visual search and a simple two-fingers button press motor task. Performance data demonstrated similar and significant dual task interference in both TBI patients and controls using a linear mixed model. However, principal component analysis showed that TBI patients and controls could be classified into different categories based on motor activity in the single compared to the dual task condition, thus reflecting the increased variability in the performance in the TBI group. Random effects between-group analysis demonstrated significantly reduced activation in the TBI group in both single task conditions in the occipital and posterior cingulate cortices, and for the visual task also in the thalami. This pattern was reversed in the dual task condition with significantly increased activation of a predominantly left lateralized prefrontal-anterior midline-parietal network in the TBI group compared to the controls. The increase in activation occurred within regions described to be engaged in healthy volunteers as dual task cost increases. This finding points to substitution, functional reorganization within the primary network subserving the task, following TBI, and demonstrates more effortful processing. Recruitment of these additional prefrontal resources may be connected to serial rather than parallel processing in low level dual tasking in TBI. Thus, in severe TBI, low level dual task performance depends on increased attentional and executive guidance.

The results of this study are interpreted as a cortical reorganization inside the executive system of vigilance and working memory in patients with TBI. Both parietal and frontal areas are recruited to compensate for damaged brain tissue.

Aim:To examine associations of structural brain abnormalities, in particular diffuse excessive high signal intensities (DEHSI), assessed by visual inspection of neonatal magnetic resonance images (MRI) with neurodevelopmental outcome at age 30 months corrected in a 3 year cohort of extremely low gestational age (ELGA) infants.Methods: 109 infants born < 27 weeks of gestation underwent conventional MRI at term-equivalent age. Images were analysed using an established scoring system (Inder et al 2003). At age 30 months corrected the infants were assessed using the Bayley Scales of Infant and Toddler Development. Results:No or mild white matter abnormalities (WMA) were seen in 86% of infants. In 14% moderate or severe WMA, and in 5% grey matter abnormalitites (GMA) were detected. DEHSI were seen in 56%. Outcome data were available for 72% of the cohort. Mean composite scores were 95 (SD±10) for cognitive scales, 97 (SD±14) for language scales, and 103 (SD±14) for motor scales. Six percent of the infants had cerebral palsy. Significant associations were seen between moderate-severe WMA and/or GMA and cognitive scores (Mann-Whitney U-test, p< 0.05) as well as language scores (p< 0.05). No significant associations were seen between MRI findings and motor scores. DEHSI were not associated with performance on the Bayley Scales. Conclusion:In our cohort of ELGA infants, moderate-severe brain abnormalitites on neonatal MRI were associated with impaired cognitive and language outcome at age 30 months corrected. The incidence of DEHSI was high, but the presence of DEHSI was not associated with adverse outcome. COMPUTERIZED COGNITIVE TRAINING IMPROVES WORKING MEMORY AND LEARNING IN EXTREMELY LOW BIRTH WEIGHT (ELBW) ADOLESCENTS