Neuropsychology

Mild traumatic brain injuries (MTBI) are the leading type of head injuries with appreciable risque of sequelae leading to functional and psychological deficits. Although mild traumatic brain injuries are frequently underdiagnosed by conventional imaging modalities, rapidly evolving techniques such as diffusion tensor imaging (DTI) reveal subtle changes in white matter integrity as a result of head trauma and play an important role in refining diagnosis, therapeutic interventions and management of MTBI. In this dissertation we use diffusion tensor imaging to detect the microstructural changes induced by axonal injuries and to monitor their evolution during the recovery process. DTI data were previously acquired from 11 subjects, football players of age 19-23 years (median age 20 years). Three players had suffered a mild traumatic brain injury during the season and underwent scanning within 24 hours after the injury with follow-ups after one and two weeks. A set of diffusion indices, such as fractional anisotropy, axial, radial and mean diffusivity were derived from the diffusion tensor. Changes in diffusion indices in concussed subjects were analyzed based on two different approaches: whole brain analysis, using tract-based spatial statistics (TBSS) and region of interest analysis (ROI). In both approaches we use a voxelwise analysis to examine group differences in diffusion indices between five controls and three concussed subjects for all DTI scans. Additional statistical analysis was performed between control groups consisting of five and three non-injured players. Both analyses demonstrated that the MTBI group reveals increase in fractional anisotropy and decreases in transversal and mean diffusivity in cortical and subcortical areas within 24 hours after the injury.

Many recent studies have confirmed that mindfulness meditation has wide ranging potential to improve the mental health and well-being of adults, though few studies have explored its potential to help younger populations. In the current study, a sample of 4th and 2nd grade students was trained in the techniques of mindfulness meditation. Baseline electroencephalograms (EEGs) were taken before the training, and again after a 10 week period of daily meditation practice. Measures of attention, creativity, affect, depression, behavioral inhibition/activation, emotion regulation, impulsive/aggressive behaviors, and social anxiety were also administered before and after the meditation practice period. Results indicate that mindfulness meditation produces increased relative left-frontal alpha activation, a brain pattern that has been associated with increased positive affect and more adaptive coping responses to aversive events. Significant post-meditation improvements in depression and creativity were also found in the experimental condition.