Neuronal mechanisms regulating the critical period of sensory experience-dependent song learning

Neuronal circuits are intensively shaped depending on experiences received during developmental critical periods. How neuronal circuits are sculpted can even affect the later development of higher cognitive functions, such as vocal communication skills. Here, we propose songbirds that learn to sing from early auditory experiences as a model for understanding the neuronal mechanisms underlying the development of multistep vocal learning. By applying the principal concepts of neuronal mechanisms for regulating the timing of critical periods, which have been well investigated by using experience-dependent mammalian cortical plasticity, we review our current understanding of the underlying neuronal mechanism of the song-learning critical period.