Evidences for shared features in the organization of the basal ganglia in tetrapods: Studies in amphibians

In a series of recent studies, the organization of the basal ganglia of amp hibians, more in particular their connectivity and chemoarchitecture, has b een thoroughly analyzed. The pattern of organization found for the amphibia n basal ganglia includes dorsal and ventral striatopallidal systems, recipr ocal connections between the striatopallidal complex and structures derived from the diencephalic and mesencephalic parts of the basal plate (striaton igral and nigrostriatal projections), and descending pathways from the stri atopallidal system to the midbrain tectum and the reticular formation of th e brain stem. A comparative analysis of the organization of the basal gangl ia in tetrapods strongly supports the notion that a primitive pattern was m ost likely present in ancestral tetrapods, and that many features can still be recognized in extant amphibians and amniotes.