Dual neuromodulatory dynamics underlie birdsong learning.

Area of Science:

• Neuroscience
• Animal Behavior
• Computational Neuroscience

Background:

• Extrinsically reinforced learning relies on dopamine signaling predicting reward prediction errors.
• Skills like speech and music can be learned intrinsically, without external rewards, but the role of dopamine is unclear.
• Juvenile song learning in zebra finches is an intrinsically reinforced process requiring dopamine in song-specific brain regions.

Purpose of the Study:

• To investigate whether dopamine signals guide intrinsically reinforced behaviors, specifically song learning in juvenile zebra finches.
• To determine if dopamine dynamics in the song basal ganglia encode learned song quality during self-directed learning.

Main Methods:

• Electrophysiological recordings in juvenile zebra finches during song learning.
• Manipulation of dopamine and cholinergic signaling in the song basal ganglia.
• Analysis of dopamine dynamics in relation to song performance quality on a rendition-by-rendition basis.

Main Results:

• Dopamine dynamics in the song basal ganglia accurately reflect the learned quality of juvenile song performance.
• Dopamine release is modulated by both midbrain reward pathways and song premotor inputs via local cholinergic signaling.
• Both cholinergic and dopaminergic signaling are essential for song learning, but only dopamine tracks performance quality.

Conclusions:

• Dopamine dynamics in the song basal ganglia encode performance quality during the long-term, self-directed learning of natural behaviors.
• This study reveals a novel role for dopamine in intrinsically reinforced learning, extending beyond traditional reward prediction error signaling.