Fig. 1

PTs innervate different subcortical targets. a Injections of retrograde tracers into four of the major subcortical targets of PTs in rat vS1. b Left panels: Example images from coronal slices of vS1 for each of the four injected targets. Dashed lines represent layer borders. The respective numbers of PTs (FG-488) were quantified with respect to all neurons (NeuN-647). Right panels: average vertical distributions of PT somata. The vertical profile of ITs represents the distribution of L5 slender-tufted neurons, as determined previously^{3, 20}. c Example image of vS1 from control experiments in which we injected FG and CTB via the same pipette into the Sp5C. d Example image from dual tracer injection illustrates overlapping, target-related sublayers in L5. e Example image from tangential slice of vS1 illustrates presence of PTs in barrel columns and septa. f Number of PTs per average (C2) barrel column and fractions of PTs projecting to two targets. Error bars denote SDs (applies to all panels and figures). g The sum of retrogradely labeled PTs from panel 1f yields that ~82% of the PNs in vS1 with thick-tufted dendrite morphologies project to the four subcortical targets investigated here. Approximately 25% innervate two of the injected targets. The number of L5 thick-tufted PNs per barrel column was determined previously^{3, 20}