Telencephalic neural precursor cells show transient competence to interpret the dopaminergic niche of the embryonic midbrain

►E10.5 telencephalic NPCs show commitment to forebrain lineages in the mesencephalon. ►E8.5 telencephalic NPCs differentiate into mesencephalic-like dopaminergic neurons in the E10.5 ventral mesencephalon. ►The instructive niche of the ventral mesencephalon decays around E12.5. ►An instructive niche (E10.5) within the ventral telencephalon remains after NPC commitment.