Do birds possess homologues of mammalian primary visual, somatosensory andmotor cortices?

Recent data on the expression of several homeobox genes in the embryonic te lencephalon of mammals, birds and reptiles support the homology of a part o f the avian pallium, named the Wulst, and at least the more-medial and supe rior parts of mammalian neocortex. This conclusion is also supported by pre vious embryological, topological and hodological data, Furthermore, new evi dence on the connections and electrophysiological properties of specific su bfields within the avian Wulst, and on the thalamic territories that projec t to these fields, supports the more-specific conclusion that a primary vis ual area-and a primary somatosensory-somatomotor area are present in the av ian Wulst; these areas are likely to be homologous to their counterparts in mammals. In spite of this, developmental, morphological and comparative ev idence indicate that some structural and physiological traits that appear t o be similar in the Wulst and neocortex (such as the lamination or binocula rity) evolved independently in birds and mammals.