The functional anatomy of the basal ganglia of birds

To study how the basal ganglia can control movement in birds, we have reinv estigated the connections of the pigeon dorsal pallidum. Our results indica te that avian basal ganglia appear to control movement through major projec tions to several premotor pretectal and tegmental centres which innervate t he tectum, and through a minor projection to a possible motor thalamic cent re which innervates the Wulst. For such control, separate striatopallidal o utput circuits appear to exist in birds that are remarkably similar to thos e described in mammals, suggesting that avian and mammalian basal ganglia m ay control movement through similar mechanisms, and that the morphological substrate for such control evolved earlier than previously thought.