The aim of the project is to determine the role of pubertal testosterone in the development of cortical volume and cognitive function during adolescence in monkeys. Castration of prepubescent rhesus was the independent variable used to examine the effect of testosterone on pubertal development. Reversal learning and prepulse inhibition tests were administered during puberty and 16 months later (PPI only). The data will tell us whether removing testosterone affects these important measures of orbitofrontal cortex functioning and dopaminergic transmission, both of which are implicated in the pathology of schizophrenia. We are also analyzing data from 3T MRI scans of the brain taken across the pubertal period to identify and correlate changes in cognitive function with reductions in cortical volume. One of the major developmental changes we have found to date is an overall reduction in brain size during adolescence. Manual tracing methods will determine if grey matter, white matter or ventricular decreases are the source of this reduction. This project will also validate the method used to obtain volumetric estimates from the MRI scans, by comparing and correlating the volume measurements for a previously determined region of interest (the amygdala) with histological stains of the same region.
