page_title: Superior colliculus
section_title: Birds
hierarchical_section_title: Superior colliculus / Other animals / Birds
context_page_description: The superior colliculus is a structure lying on the roof of the mammalian midbrain. In non-mammalian vertebrates, the homologous structure is known as the optic tectum, or optic lobe. The adjective form tectal is commonly used for both structures.
  In mammals, the superior colliculus forms a major component of the midbrain. It is a paired structure and together with the paired inferior colliculi forms the corpora quadrigemina. The superior colliculus is a layered structure, with a number of layers that varies by species. The layers can be grouped into the superficial layers and the deeper remaining layers. Neurons in the superficial layers receive direct input from the retina and respond almost exclusively to visual stimuli. Many neurons in the deeper layers also respond to other modalities, and some respond to stimuli in multiple modalities. The deeper layers also contain a population of motor-related neurons, capable of activating eye movements as well as other responses.
  The general function of the tectal system is to direct behavioral responses toward specific points in egocentric space.
context_section_description: In birds the optic tectum is involved in flight and is one of the largest brain components. The study of avian visual processing has enabled a greater understanding of that in mammals including humans.
caption: Drawing by Ramon y Cajal of several types of Golgi-stained neurons in the optic tectum of a sparrow.
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