Shape and structure of the avian brain an old problem revisited.

Previously two approaches have been used to study the relation of shape and structure of the avian brain. One possibility is to consider shape, size and position of the brain as elements of the architecture of the head. The other approach was to consider the shape of the brain as expression of its structure. The significance of the two approaches for the explanation of the shape of the avian telencephalon is discussed in the light of recent data of brain organization. The two approaches are complementary in the explanation of position, size and shape of the brain.