With the use of ATAC-350 (Nihon Kohden) a study was made of the effects of wearing contact lenses on the unit discharges of the reticular formation induced by photic stimulation in rabbits.1) By use of an interval histogram, it was demonstrated that wearing contact lenses led to a marked increase in the frequency of unit discharges in the midbrain reticular formation induced by photic stimulation.2) In the pulse count histogram, an increase in the frequency of the unit discharges of 90msec latency induced by photic stimulation was observed by wearing contact lenses.3) It was assumed that the increase of the unit discharges was due to an increase of activity of the reticular formation which was elicited by the pain following wearing contact lenses.
The mechanism of microvibration(MV)was studied electrophysiologically by glving series of photic stimulation on rabbit eye lids.1.Five components were observed in the MV in response to the photlc stimulation.2.AIl components disapPeared with the elevation of intraocular pressure or after the cut-off on the optic chiasma.3.AIl components increased in amplitude with a 100Hz stimulation on the brain stem reticular formation(RF). And they were$uppressed remarkably following an impairment of the RF in both sides.4. With an impairment of the oculomotor nuclei,all components disapPeared.5.They remained intact after a wide-range impairment on the occipital cortical area as well as on both sides of Iateral geniculate body.6. When a 100Hz stlmulation was given to the cortex and hipPocampus as well,a facilitatory effect on all components was found present.7.All components decreased with a 3Hz stimulation on the ventral anterior nuclei(VA)which belongs to the diffuse thalamo-cortical projection system.All components either increased or decreased with a 8Hz stimulation on the VA.All components increased with a 100Hz stimulation on the VA.Following an impalment of the VA,all components increased.8.An inhibitory effect was observed on all components with the administration of barbiturate and diazepamThough chlorpromazine had an inhibitory effect in general on all components,it showed a facilitatory effect temporarily when given in large quantity. CDP-choline, one of the central nerve stimulants was found having a facilitatory effect over the MV.9.In an experiment in which MV and electrical change of photopalpebral reflex(PPR)were recorded simultaneously,PPR5 decreased and PPR6 as well as the MV disappeared with the impairment of the RF and the oculemotor nuclei in both sides, whereas little change was seen in PPR1 through PPR4.10. Two peaks were found in the pulse count histogram of RF unit discharges evoked by the series of photic stimulation.Barbiturate as well as diazepam had an inhibitory effect on the peaks. Chlorpromazine, however, had an inhibitory effect only on the second peak.11. When a man was given a series of photic stimulation through an eye with the eye shut up, only components for central nervous system were recorded in PPR from the covered e ye, and they were found similar to the MV wave simultaneously recorded.These components as well as the MV were increased by giving Pain stimli or mathematical questions.Components for the central nervous system in PPR, especially PPR6 and all components in the MV were thus considerd to have a same origin in the C. N. S.Furthermore, it was demonstrated that this reflex was related not only to the level of consciousness but also to the emotional aspect.
Experiments with, rabbits were made of M wave and H wave in reference to the effects of wearing contact lenses.1) On the p eak time of M wave and H wave in the m. gastrocnemius induced by the tibial nerve stimulation, wearing contact lenses showed almost no effects.2) The amplitude of M wave was not changed significantly, w hile that of H wave was increased by wearing contact lenses.3) It was assumed that the increase in amplitude of H wave was due to facilitation of the monosynaptic reflex following inhibition of the reticular formation.
