Supplementary Figure 2: Anatomical cortical hierarchy derived from N = 1,243 laminar-specific interareal projections in monkey cortex.

(a) Fraction of external labeled neurons (FLNe). Target area i is injected with a retrograde tracer that labels neurons in many source areas; the FLNe in source area j is then defined as the fraction of all external labeled neurons terminating in area i that originated in source area j. Each row of the FLN matrix is therefore normalized to 1. Measurements which yielded no labeled neurons are marked in grey. (b) Fraction of supragranular layer neurons (SLN), defined as the fraction of neurons in an interareal projection (to target area i from source area j) originating in supragranular layers. An SLN of 1 indicates that all labeled projection neurons were of supragranular origin, reflecting a pure feedforward connection; an SLN of 0 indicates that all projection neurons originated in deep infragranular layers, reflecting a pure feedback connection. Measurements which yielded no labeled neurons are marked in grey. (c) Model-estimated hierarchy levels for 89 cortical regions. The blue line indicates hierarchy levels estimated by the model after shifting and re-scaling them to lie on the unit interval. The red indicates hierarchy values passed through a logistic function to remove the nonlinearity introduced by the logit link function in the GLM fitting procedure. The monotonicity of this transformation preserves the order of the cortical regions and therefore does not affect the Spearman rank correlations reported in the main text. (d) Group-averaged T1w/T2w map values for 89 cortical areas in the monkey.