Figure 14. Bundling of VPM axons projecting into a PW column defines a ‘thalamocortical (TC) unit’ and an ‘intracortical (IC unit)’ as basic building blocks of vS1.

A, projection of 3D VPM axon reconstructions onto sagittal plane. Individually reconstructed axons were registered into a standard 3D reference frame of vS1. The ensemble of reconstructions shows that bundling of VPM axons is restricted approximately to the dimensions of a histochemically delineated average single column. Column borders are outlined by a grey box. B, projection of dendrites of a PW column onto sagittal plane. The dendrite column consists of 3D‐reconstructed somata and their dendrites registered into a standard 3D reference frame of vS1. Dendrites of the different excitatory cell types are shown in different colours. The L5tt cell dendrites are shown in ochre. The width of cytologically delineated cortical layers is given on the left. C, projection of axons of a PW column onto thalamocortical plane. This column, located in the middle, consists of reconstructed and registered axons of 10 excitatory cell types. Their axons are shown in cell‐type‐specific colours, e.g. those of spiny stellate cells are in green. Upper and lower outlines of the PW column and of four SuW columns are shown in white. Pia is on top, white matter on bottom. The borders of the granular layer are indicated by the two white outlines in the middle of the columns. From Oberlaender et al. (2012 b) and Narayanan et al. (2015), with permission.