Fig. 6
Corticostriatal projections map the organization of corticocortical connectivity in IT-type but not PT-type projections. a Sensory and motor cortex injections label reciprocal intracortical projections between topographically related areas. b, c, f, g IT-type injection examples shown contrast a pair of strongly connected cortical areas (red vS1 and yellow vM1 injections) with a non- topographically aligned area (green fM1 injection). Scale 0.5 mm (all panels). vS1 axons (red) overlap poorly with fM1 neurons (green). Cortical correlations are measured using fluorescence from voxels in either M1 (top) or S1 (bottom). For one pair (b, c), these are poorly correlated in both injection sites (−0.1845 and 0.0644; b, c top and bottom) as well as the striatum (−0.0116; b, c middle). In contrast, vS1 axons (red) overlap well with vM1 neurons (yellow) and are strongly correlated in both injection sites (0.4028 and 0.3495; f, g top and bottom) as well as the striatum (0.4375; f, g middle). d, e Scatterplot of co-correlations of corticocortical connectivity (using injection site overlap) and corticostriatal connectivity for IT-type projections. Each individual point represents the corticostriatal correlations (x-axis) and injection site correlation (y-axis) for a single pair of injection cases with corticocortical correlation computed at either M1 (d) or S1 injection sites (e). Red points on the scatterplot compare sensory and motor injections. Black points add comparisons to frontal areas (M2 and ALM). Green and teal arrows and points indicate specific points corresponding to the example injections shown. h, i Scatterplot of co-correlations of corticocortical connectivity and corticostriatal connectivity for PT-type projections. j Co-correlations of corticocortical connectivity and corticostriatal connectivity are re-assessed, with corticostriatal correlations (y-axis) calculated using subsets of striatal voxels along the anterior/posterior axis in 250 µm segments (x-axis, in mm). Co-correlation is plotted for IT-type (red) and PT-type (blue) injections
