Functional changes between seasons in the male songbird auditory forebrain

Area of Science:

• Neuroscience
• Animal Behavior
• Bioacoustics

Background:

• Songbirds, like European starlings (Sturnus vulgaris), use complex acoustic signals for communication.
• Seasonal changes in the importance of social versus individual information in songs are known, but neural response changes are not well understood.
• Understanding neural processing of learned communication signals is crucial for deciphering complex social behaviors.

Purpose of the Study:

• To investigate seasonal changes in auditory processing of conspecific songs in male European starlings using in vivo functional magnetic resonance imaging (fMRI).
• To examine how neural responses differ for songs conveying species-specific, group identity, or individual identity information across seasons.
• To identify brain regions involved in processing different types of song information and assess hemispheric lateralization.

Main Methods:

• Used in vivo functional magnetic resonance imaging (fMRI) to measure brain activity in male European starlings.
• Exposed birds to songs with varying informational content (species/group vs. individual identity) during and outside the breeding season.
• Analyzed blood-oxygen-level-dependent (BOLD) responses in auditory regions, particularly the caudomedial nidopallium (NCM).

Main Results:

• The caudomedial nidopallium (NCM) is confirmed as a key auditory region for processing conspecific songs.
• Seasonal changes in song processing were localized to a caudal region of the NCM.
• Rostral NCM showed consistently higher BOLD responses to individual identity songs compared to species/group songs, irrespective of season. Differentiation was biased toward the right hemisphere.

Conclusions:

• Auditory processing of behaviorally relevant conspecific communication signals exhibits seasonal plasticity in European starlings.
• Specific regions within the NCM show differential responses to song types based on informational content and season.
• The findings suggest a neural basis for seasonal shifts in the importance of social versus individual recognition in songbird communication.