Effects of sciatic stimulation upon the efferent impulses in the long ciliary nerve of the cat.

It was shown by Bronk, Pitts and Larrabee (2), Cannon, Raule and Schaefer (4) and Sell, Erdelyi and Schaefer (14) that a marked increase of the efferent impulses in the sympathetic nerves, particularly in the cardiac sympathetic nerves and renal branch of the abdominal sympathetic nerves, was evoked by stimulating the central end of the peripheral sensory nerves. It was pointed out by them, furthermore, that such a reflexly increased activity in the sympathetic nerves was abolished with the removal of the hypothalamus (2) or with the transection of the upper cervical segments (14). However, the reflex response of the efferent impulses in the long ciliary nerve to nociceptive stimuli has not been studied by any authors. The object of the present experiments was to find the reflex responses in the long ciliary nerve produced with sciatic stimulation, as well as, the role of the upper brain upon the development of these responses, observing the action potentials from individual fiber of the long ciliary nerve. Thus it has been demonstrated that, if a certain condition be satisfied, the spontaneous discharge from the long ciliary nerve is not only facilitated, but also inhibited by stimulating the sciatic nerve centrally.