Cellular transcriptomics reveals evolutionary identities of songbird vocal circuits

Area of Science:

• Neuroscience
• Comparative Biology
• Genomics

Background:

• Birds exhibit complex behaviors like vocal learning, traditionally associated with the mammalian neocortex.
• The neural basis for these shared behaviors between birds and mammals, given their distinct brain structures, remains unclear.

Purpose of the Study:

• To investigate the developmental origins and transcriptional similarities of songbird vocal circuits compared to the mammalian neocortex.
• To understand the neural underpinnings of advanced avian behaviors.

Main Methods:

• Single-cell RNA sequencing was employed to analyze the neuronal repertoire of the songbird song motor pathway.
• Transcriptional profiles of avian neurons were compared with those of mammalian neocortical neurons.

Main Results:

• Glutamatergic vocal neurons in songbirds showed transcriptional similarities to mammalian neocortical projection neurons.
• However, avian neurons exhibited regulatory gene expression patterns more akin to ventral pallium neurons.
• A major class of avian neurons in this pathway is largely absent in the mammalian neocortex.

Conclusions:

• Songbird vocal circuits and the mammalian neocortex appear to have divergent developmental origins.
• Despite distinct origins, specific neuronal types within these circuits display significant transcriptional similarities, suggesting convergent evolution or shared ancestral elements.