In 3 pigeons ablation of the posterodorsolateral neostriatum impaired delayed alternation without affecting visual discrimination. In mammals the same selective deficit is produced by lesions in the prefrontal system. The presently ablated neostriatal region resembles the mammalian prefrontal cortex also by being richly innervated with dopaminergic fibers. This region is clearly separated from paleostriatum augmentatum and archistriatum which also have a strong dopaminergic innervation. The presence of a prefrontal cortex-like formation in a bird species raises the possibility that all higher vertebrates are equipped with this neural device.