The pretectal light input to the pupilloconstrictor neurones.
D000200:Action Potentials; D000221:Adaptation, Ocular; D000818:Animals; D002415:Cats; D008027:Light; D008636:Mesencephalon / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D011680:Pupil / Q000294:innervation*; D012018:Reflex