It still is the main integrating centre for eye movements. In mammals, and especially primates, the massive expansion of the cerebral cortex reduces the tectum ("superior colliculus") to a much smaller fraction of the whole brain. In some non-mammal species, including fish and birds, the tectum is one of the largest components of the brain.
In other species, the tectum is involved in a wide range of responses, including whole-body turns in walking rats, swimming fishes, or flying birds tongue-strikes toward prey in frogs fang-strikes in snakes, etc. In primates, the tectum is also involved in generating head turns, arm-reaching movements, and shifts in attention which do not involve any movements.
If strong enough, this causes an eye movement. Visual input from the retina, or "command" input from the cerebral cortex, create a "bump" of activity in the tectal map. In primates, the tectum ("superior colliculus") directs eye movements. He has received numerous awards and honors, most recently the Cortical Discoverer Prize of the Cajal Club, and delivered distinguished lectures world. If neurons at a point in the map fire, it starts a response towards the corresponding point in space. degree in Electrical Engineering from the Indian Institute of Technology, Kanpur, and the PhD degree in Electrical Engineering from Vanderbilt University, Nashville. The diagram is based on human anatomy.Įach layer of the tectum contains a topographic map of the surrounding world. When human anatomy textbooks use the term superior colliculus they are referring to the tectum. The tectum does preliminary visual processing, and controls eye movement. This is at the back of the cerebral cortex. In mammals, however, most of the work is done in the visual cortex. In vertebrates such as fish, reptiles and birds, it is the main visual processor of the brain. The optic tectum is a major part of the midbrain of vertebrates.
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