The role of inhibitory interneurons in song learning in zebra finches

Abstract

Inhibition has been shown to play an important role in determining the critical period of development of sensory systems but its role in motor system is unknown. Here, I study the zebra finch, a bird that develops a motor skill during a critical developmental period. In juvenile zebra finches, learning of song syllables during critical period is accompanied by a corresponding stepwise increase in inhibition in HVC (used as proper name). Adult zebra finches have crystallized songs which are protected from further change influenced by external auditory playback by the inhibitory interneuron network in HVC. In this study, I show that pharmacological inactivation of the inhibitory interneuron network in adults leads to reopening of the critical period and induces plasticity in song. Since HVC is a relay center between the auditory and motor systems, I provided an additional auditory playback during pharmacological interneuron inactivation and observed its effect on the changes in song. I quantified changes in spectral features of song syllables and changes in linearity, consistency and stereotypy of syllable sequencing. My results show that the limitation of HVC interneuron efficacy leads to a window of opportunity for zebra finches to learn a new song which seems to be guided by imitation learning. Reopening of the critical period in later stages of development by limiting interneuron signaling opens possible avenues for fine-tuning learned motor sequences in a guided manner.