Molecular diversity and evolution of neuron types in the amniote brain

The existence of evolutionarily conserved regions in the vertebrate brain is well established. The rules and constraints underlying the evolution of neuron types, however, remain poorly understood. To compare neuron types across brain regions and species, we generated a cell type atlas of the brain of a bearded dragon and compared it with mouse datasets. Conserved classes of neurons could be identified from the expression of hundreds of genes, including homeodomain-type transcription factors and genes involved in connectivity. Within these classes, however, there are both conserved and divergent neuron types, precluding a simple categorization of the brain into ancestral and novel areas. In the thalamus, neuronal diversification correlates with the evolution of the cortex, suggesting that developmental origin and circuit allocation are drivers of neuronal identity and evolution.

Automated summary

The existence of evolutionarily conserved regions in the vertebrate brain is well established, but the rules and constraints underlying the evolution of neuron types remain poorly understood. By comparing neuron types across brain regions and species, both conserved and divergent neuron types were identified. The diversification of thalamic neurons is correlated with the evolution of the cortex, indicating that developmental origin and circuit allocation play a role in neuronal identity and evolution.