Fig. 4

FOXP2 and CASK protein signals co-localize within striatal and cerebellar neurons. A Nissl stain of sagittal section of the male zebra finch brain at the level of the cerebellum and Area X (dotted white circle). B Nissl stain of the zebra finch telencephalon at the level of striatal Area X (dotted white circle) which is visible bilaterally. C–F Photomicrographs show immunostain signals for DNA (DAPI-blue), FOXP2 (green) and CASK (red) as well as a merged image (far right panel in each row). C As expected, cerebellar Purkinje neurons do not show strong DAPI signals (left panel; white arrowheads) but do co-stain for FOXP2 and CASK. D Striatal neurons from an adult male zebra finch housed with a female (mixed singer; see Methods) show co-localization of FOXP2 and CASK signals (white arrowheads). In striking contrast, those from a male who sang alone (E) show undetectable FOXP2 signals and strong CASK signals whereas those from a non-singer (F) show robust FOXP2 signals and undetectable CASK. See Supplementary Fig. 2 for negative controls. A Anterior, D Dorsal, L lateral. Scale bar = 20um for panels (C–F)