Effects of Adolescent Synaptic Pruning

The loss of brain cell (neuron) connections (synapses) through human development, known as synaptic pruning, has been characterized in postmortem studies but how this proceeds in live humans as they age into adulthood is not well understood. This study will use the PET tracer \[11C\]UCB-J which provides a direct measure of synaptic density, in conjunction with previously acquired ultra-high field MRI, in a group of young adults in order to understand how standard MRI-based measures reflect changes in the density of synapses. PET \[11C\]UCB-J is known to measure the density of synaptic connections by measuring a protein (SV2A) present in synapses. A comparison of results from the current study with MRI-based measures of byproducts of synaptic membrane breakdown from childhood to early adulthood will allow assessment of how non-invasive MRI reflects synaptic pruning through development, facilitating studies of how the brain changes through adolescence and into adulthood, which is needed to identify patterns of development associated with the emergence of mental illness.