NeuroImage
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Early adolescence is a time of rapid change in neuroanatomy and sexual development. Precision in tracking changes in brain morphology with structural MRI requires image segmentation with minimal error. Here, we compared two approaches to achieve segmentation by image registration with an atlas to quantify regional brain structural development over a 7-month interval in normal, early adolescent boys and girls. ⋯ Subcortical structures did not show consistent changes. Thus, longitudinal MRI assessment using robust registration methods is sufficiently sensitive to identify significant regional brain changes over a 7-month interval in boys and girls in early adolescence. Increasing the temporal resolution of the retest interval in longitudinal developmental studies could increase accuracy in timing of peak growth of regional brain tissue and refine our understanding of the neural mechanisms underlying the dynamic changes in brain structure throughout adolescence.
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Noise exposure at high intensities leads to a temporary shift of hearing thresholds (TTS) and is followed by a permanent threshold shift (PTS). Permanent threshold shift is not only associated with cochlear damage as the primary site-of-lesion, but also with subsequent structural and functional changes within the central auditory pathway. The aim of the present study was to monitor neuronal activity within central auditory structures in mice after noise exposure at different time intervals using manganese-enhanced magnetic resonance imaging (MEMRI). ⋯ Sustained manganese accumulation was present in the auditory brainstem after moderate acoustic stimulation as well without PTS induction. The long-lasting enhancement of MEMRI signals suggests a noise-induced activity increase of various calcium-dependent processes of different origin (such as neuroprotective mechanisms). The present findings could be helpful to better understand the time-course of different symptoms in NIHL and the individual susceptibility to noise.