“…Electrophysiological studies in the rat showed that the nucleus praetectalis olivaris (NPO) is the pretectal relay station of the pupilloconstrictor pathway (Trejo & Cicerone, 1984;Clarke & Ikeda, \985a,b). A cortical influence upon pupil constriction has been described in studies using electrical stimulation in rabbit Inoue & Kiribuchi, 1985), cat (Barris, 1936;Shoumura et al, 1982Shoumura et al, , 1984, and monkey (Jampel, 1960). The ipsilateral projection to EW does not exist in birds and rabbits, is relatively weak in cats, and possibly again absent in monkeys (Ranson & Magoun, 1933;Magoun et al, 1936;Yoshioka, 1957;Matsushita, 1959;Steiger & Buettner-Ennever, 1979;Reiner et al, 1983).…”