Evolution of pallium, hippocampus, and cortical cell types revealed by single-cell transcriptomics in reptiles

Science. 2018 May 25;360(6391):881-888. doi: 10.1126/science.aar4237. Epub 2018 May 3.


Computations in the mammalian cortex are carried out by glutamatergic and γ-aminobutyric acid-releasing (GABAergic) neurons forming specialized circuits and areas. Here we asked how these neurons and areas evolved in amniotes. We built a gene expression atlas of the pallium of two reptilian species using large-scale single-cell messenger RNA sequencing. The transcriptomic signature of glutamatergic neurons in reptilian cortex suggests that mammalian neocortical layers are made of new cell types generated by diversification of ancestral gene-regulatory programs. By contrast, the diversity of reptilian cortical GABAergic neurons indicates that the interneuron classes known in mammals already existed in the common ancestor of all amniotes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biological Evolution*
  • Cell Tracking / methods*
  • GABAergic Neurons / classification
  • GABAergic Neurons / cytology
  • Gene Expression Profiling / methods*
  • Hippocampus / cytology*
  • Neocortex / cytology*
  • Neuroglia / classification
  • Neuroglia / cytology
  • Neurons / classification
  • Reptiles*
  • Single-Cell Analysis / methods*