Increased Fos expression among midbrain dopaminergic cell groups during birdsong tutoring

Area of Science:

• Neuroscience
• Animal Behavior
• Bioacoustics

Background:

• Avian vocal learning requires memorizing song patterns and using auditory feedback for vocal matching.
• Models suggest social cues during tutoring activate neuromodulatory systems, imbuing tutor songs with incentive value.
• This implies that stimuli during social tutoring activate reward-signaling cell populations.

Purpose of the Study:

• To investigate if social tutoring activates reward processing brain regions in juvenile male zebra finches.
• To determine the role of familiar versus novel tutors in activating these neural pathways.
• To explore the neural mechanisms underlying song acquisition and reward association.

Main Methods:

• Utilized immunocytochemistry to detect c-Fos protein expression, an indicator of neural activity.
• Exposed juvenile male zebra finches to live familiar and novel male tutors.
• Quantified Fos+ cell density in reward-related brain regions (VTA, SNc) and the periaqueductal gray.

Main Results:

• Exposure to a live tutor significantly increased Fos+ cells in the ventral tegmental area (VTA) and substantia nigra pars compacta (SNc).
• A familiar tutor was more effective than a novel tutor in increasing Fos expression in the VTA and SNc.
• Increased Fos labeling was also observed in the periaqueductal gray, with familiar tutors showing a stronger effect.

Conclusions:

• Social tutoring, particularly by a familiar tutor, activates dopaminergic midbrain nuclei (VTA/SNc) associated with reward processing in songbirds.
• This activation may contribute to establishing sensory representations crucial for vocal motor learning.
• The findings support the hypothesis that social and auditory cues during tutoring enhance song acquisition by linking it to reward pathways.