Tectospinal neurons in the cat have discharges coding gaze position error.

Tectospinal neurons (TSNs) in the caudal superior colliculus of the alert behaving cat have a sustained discharge that depends on the magnitude and direction of the vector between a food target and the visual axis. Each TSN has its 'optimal' vector for which it will be activated at a maximum discharge rate independent of whether the animal's head is free or fixed. The discharge is not due to prolonged stimulation of a TSN's receptive field since the discharge persists even when the target is not visible.