The activity of the cilio-spinal centers and their inhibition in pupillary light reflex

Abstract

It has been stated that in pupillary light reflex the short ciliary nerve innervating the circular muscles of the iris plays an important role as the efferent pathway concerned with the reflex, and constriction of the pupil takes place by a contraction of these muscles alone. On the other hand, in this reflex the physiological role of the sympathetic nerve innervating the radial muscles of the iris is known little. Our recent experiment (14) has shown that the impulse discharge from the short ciliary nerve is increased during the light illumination of the retina. We have recently succeeded, furthermore, in recording action potentials from the long ciliary nerve originated from the ciliospinal centers of the spinal cord and have attempted to study the role of the sympathetic nerve upon the pupillary constriction in the light reflex, as well as, to determine whether the ciliospinal centers isolated completely from other central nervous systems and from the afferent nerves have the ability to discharge spontaneous impulses. In addition, the purpose of the experimentis to elucidate the effect of adrenalin and asphyxia upon the isolated ciliospinal centers. © 1960, PHYSIOLOGICAL SOCIETY OF JAPAN. All rights reserved.