Corollary Discharge

Imagine an animal walking through a forest. As it moves, branches brush against its skin, twigs snap at its feet, and patterns of light and shade alternate across its eyes. In principle, the animal should be startled by these sensory events. The activation of its skin receptors could be interpreted as caused by a fly landing on its leg, and the sounds and shadows as meaning a predator is looming. Surprisingly, the animal is not startled by these sensory events; they are expected, partly because the animal has access to an internal report of its own movements called corollary discharge.

Each of an animal's movements is initiated by motor commands originating from movement areas of the brain that travel peripherally to activate the appropriate muscles. Neural ...