The hyperpallium is a brain structure in birds and the destination for lemnothalamic projection. The projections as well as the granule cells at the destination of the lemnothalamic projections to the hyperpallium are similar in morphology, electrophysiology, retinotopic organization, and columnar organization to the striate cortex in mammals. These avian granule cells are thought to have evolved independently in birds, as they do not appear in reptiles.