Neurons in the caudal third of VP massively innervate the second somatosensory cortex (S2). a, Representation on the cortical flatmap of retrograde tracer injections in S1 and in S2. Three retrograde tracer deposits in S2, with no involvement of S1, are represented in different colors. For comparison, several retrograde tracer injections in S1 are represented in gray. b, Position of the retrogradely labeled cell somata in VP. Diagrams depicting a series of coronal sections of the VP complex are shown from anterior (top-left) to posterior (bottom-right). Cell somata (dots) labeled in different experiments are plotted using the same colors as in panel a; each dot represents a labeled cell. In this diagram, VP subdivisions are identified using the standard denominations in Paxinos and Franklin (2019). AP levels are indicated under each section. Scale bar: 250 μm (b). Abbreviations: GI, granular insular area; S1, primary somatosensory area; S2, second somatosensory area; Str, striatum; VPL, ventral posterolateral nucleus; VPM, ventral posteromedial nucleus; VPMpc, parvicellular part of VPM.