Fig. 2.

Aspects of cortical architecture determining population sizes. a Laminar neuron densities for the architectural types in the model. Type 2, here corresponding only to area TH, lacks L4. We treat L1 as containing synapses but no neurons. Data provided by H. Barbas (personal communication). b Total thickness versus logarithmized overall neuron density and linear least-squares fit ($r=-0.7,p=0.005$). c Relative laminar thickness (see Supplementary Table S3) versus logarithmized overall neuron density and linear least-squares fits (L1: $r=-0.51,p=0.08$, L2/3: $r=-0.20,p=0.52$, L4: $r=0.89,p=0.0001$; L5: $r=-0.31,p=0.36$, L6: $r=-0.26,p=0.43$). Total cortical thicknesses D(A) and overall neuron densities for 14 areas from Hilgetag et al. (2016), Table 4. The overall densities are based on Nissl staining for 11 areas and for 3 areas on NeuN staining. Laminar neuron densities are based on NeuN staining for all 14 areas. Values based on NeuN staining are linearly scaled to account for a systematic undersampling as determined by repeat measurements in the 11 aforementioned areas