Tonotopic organization of MGBv projections to AI. A, Schematized coronal section through the mouse brain indicating the relative locations of AI and MGBv (gray shading), the position of CTB injections, and the plane of the section used to achieve the thalamocortical slice (dashed black line). B, Schematic representation of major brain nuclei contained within the auditory thalamocortical brain slice. C, Auditory thalamocortical slice immunoreacted for parvalbumin (blue). CTB-green and CTB-red were injected into 7 and 22.6 kHz domains in AI, respectively. SII, Secondary somatosensory cortex; Int C, internal capsule; str, superior thalamic radiation; Rt, reticular nucleus; VPL, ventral posterolateral thalamic nucleus; VPM, ventral posteromedial thalamic nucleus; LGN, lateral geniculate nucleus; Po, posterior thalamic complex; bic, brachium of the inferior colliculus; DNLL, dorsal nucleus of the lateral lemniscus; Ent, entorhinal cortex; PRh, perirhinal cortex; R, rostral; M, medial. Scale bar, 0.25 mm.