Fig. 4. Challenges for transcriptomic classification.

a, Gradients in morphological size and complexity across the rostrocaudal extent of the cortex. b, Graded transcriptomic variation across the human cortex encodes rostrocaudal position on the cortical sheet. c, Transcriptomic cell types can be aligned across species based on shared molecular specification, but often at a lower level of resolution than the finest types observed in a given species. Images in a adapted with permission from ref. ⁸², Oxford Univ. Press; in b and c, adapted with permission from refs. ⁸³ and ⁶¹, respectively, Springer Nature.