Event:

Please use following link to join the zoom meeting:

https://lmu-munich.zoom.us/j/97153244013?
pwd=aExBSmVZR3pZMmFUUXMyU2g5N2ludz09

Zoom meeting ID: 971 5324 4013
Passcode: 146880

Abstract:
The ongoing revolution in cell-resolved molecular profiling has transformed biology and offers
unprecedented opportunities to understand how brains function, develop, and evolve. These new approaches
enable researchers to compare molecularly identified neuronal classes across species, allowing a more direct
analysis of neuronal evolution. The evolution of the six-layered neocortex is often credited with an increased
capacity for complex behaviors and cognition in humans and other mammals. However, birds lack a layered
neocortex but nonetheless display complex behaviors including vocal learning, tool use, and problem-
solving. It is unclear to what extent these advanced behavioral repertoires across species are supported by
shared or distinct neural circuits. We used single-cell RNA-sequencing in songbirds to characterize the
molecular identities of cells in the song motor pathway, a forebrain circuit with function and connectivity
that has been likened to the mammalian neocortex. Song motor pathway glutamatergic neurons have gene
expression patterns similar to those described in neocortical projection neurons, but at the level of
transcription factor expression, display stronger similarity to neurons in the mammalian ventral pallium. We
observed multiple GABAergic neuron classes that are conserved across birds, non-avian reptiles, and
mammals, yet the most abundant class strongly resembles an interneuron type not found in the neocortex but
in subcortical regions like the striatum and amygdala. Together our results indicate that avian song control
circuits and the mammalian neocortex are located in non-homologous forebrain regions yet contain
overlapping cellular types and connectivity patterns. This work points to a promising approach in which
single-cell profiling methods can be leveraged to characterize the shared principles underlying vertebrate
neural circuit organization as well as the cellular innovations that support species-specific behaviors.