抄録
Afferent discharges from the so-called mixed ciliary nerves were recorded unipolarly with a platinum wire electrode (200 μ in diameter) in rabbits anesthetized with pentobarbital sodium and immobilized with D-tubocurarine. The cornea was mechanically stimulated either with a calibrated nylon-monofilament (pressure: 25-300 mg, diameter: 135 μ-von Frey's hair) or with a blunt glass rod. It was also thermally stimulated by means of dropping Ringer's solutions of various temperatures (5-35..) in 2-10.. steps. And the following results were obtained.
1) Twenty-nine units exhibited a low threshold for mechanical stimulation. They were characterized by the lack of spontaneous discharges. Twenty-eight units out of them transiently increased their discharges in response to thermal stimulations at 5.. or at both 5.. and 15... One unit did not respond to thermal stimulations. The average conduction velocity was 8.1m/sec S.D.: 4.9m/sec, n=18). Their receptive fields were either round (1-2mm in diamet e (r) or oval (the length of the long axis: 5 mm) in shape.
2) Three units showed spontaneous discharges. They responded to various thermal stimulations. For example, they increased their discharges when the cornea was stimulated with a drop of Ringer's solution which was lower in temperature by 2C than the cornea. On the other hand, they decreased their discharges or disappeared completely when the cornea was stimulated with a drop of the solution having a temperature higher than that of the cornea. These results indicate that the discharge rate of these units was temperature-dependent. Exactly the same results were obtained in 17 cases in which multi-unit discharges were observed.
3) One unit and one multi-unit exhibited low thresholds for both thermal and mechanical stimulations.
