Fig. 2.

Photomicrographs of retrograde label within DLM produced by injections of RDA into different subregions of lMAN_core showing comparable patterns of topography within the DLM_DL→lMAN_core circuit in birds of different ages. Injection sites in lMAN (black) are shown in coronal schematics in the left column, anddashed outlines depict Nissl-defined borders of DLM in each photomicrograph on the right. Inset(below the lMAN schematics) demonstrates the oval dorsolateral subregion of DLM (DLM_DL) and the crescent-shaped ventromedial part (DLM_VM). A, Retrograde label in the ventral and intermediate parts of DLM_DL resulting from an injection into ventral intermediate and lateral lMAN_core in an adult bird. B, An injection of RDA into dorsolateral lMAN_core produced retrograde label specifically within the ventral intermediate part of DLM_DL in a 35 d bird. C, RDA-labeled neurons localized to ventrolateral DLM_DL from an injection into dorsolateral lMAN_core in a 20 d bird. Retrograde label did not extend into the ventromedial subregion of DLM or into more dorsal subregions of DLM_DL in any of these birds. Scale bar, 200 μm.