This document summarizes a presentation about songbirds and the role of parvalbumin-positive (PV+) interneurons in vocal learning. It finds that: 1) PV+ interneuron addition occurs during songbirds' critical period for vocal learning, peaking around the time birds begin singing independently. 2) Higher rates of PV+ interneuron addition were seen in isolated songbirds, which may allow prolonged neural plasticity and better copying of tutor songs. 3) While the original question of whether songbirds have songs stuck in their heads was not directly addressed, the findings suggest PV+ interneurons are involved in memorization and production of song.