An electro-physiological study was made in an attempt to investigate the mechanism of the electrical change of photopalpebral reflex (PPR), and in addition, visual evoked response (VER) as well as microvibration (MV) of the eyelid were studied simultaneously in rabbits.
The results obtaind were as follows.
1. Four components (PNB
1, PN
2, PN
3 and PN
4) in PPR and six components (VP
1, VN
1, VN
2, VN
3, VN
4 and VP
2) in VER were observed in response to the photic stim ulation through bipolar lead. On the other hand, six components (PPR
1, PPR
2, PPR
3, PPR
4, PPR
5 and PPR
6) in PPR and five components (VER
1, VER
2, VER
3, VER
4 and VER
5) in VER were observed through monopolar lead.
2. All components of PPR and VER disappeared after the elevation of intraocular pressure.
3. The components of PPR were still observed after removal of the M. orbicularis oculi.
4. PPR
5 and PPR
6 disappeared after cut of the optic nerve at the chiasuma fasciculum opticum.
5. PPR and ERG were recorded simultaneously, and the early components of PPR (PPR
1-4) were found to be identical with “a” wave, “b” wave and oscillatory potentials of ERG.
6. PPR
5 and PPR
6 disappeared after transection of the brain stem.
7. Following the impairment of such nucleus as VA and CM which belong to the diffuse thalamocortical projection system, facilitatory effect on PPR
6 was observed.
8. Four components (MV
1, MV
2, MV
3 and MV
4) were observed in MV which is the accelerative change of the microvibration of the eyelid evoked by photic stimulation.9. Inhibitory effect was observed in all components of MV, PPR' and PPR6, following the administration of gallamine.
10. In most cases, inhibitory effect on PPR
1 and PPR
6 was observed while facilitatory effect on each component from PPR
2 to PPR
5 was observed following the administration of such drugs as barbiturate, chlorpromazine and diazepam. Inhibitory effect on VER
5 was observed while facilitatory effect on PPR
6 and VER
5 was observed following the administration of CDP-choline.
11. Based on the result s of the experiments of hippocampal stimulation, it was postulated that there were histological differences in the site of stimulation in the hippocampus and that both modulation systems of PPR and VER were influenced by barbiturate whereas the modulation system of VER was influenced by chlorpromazine.
12. PPR in man recorded from upper and lower eyelids by monopolar lead and bipolar lead respectively. Four components of which peak latencies were 15,32,45 and 57msec were observed by bipolar lead. When one eye was covered and photic stimulation was emitted to the contralateral eye, all components but the component of 57msec latency disappeared in the covered eye.
From these results, it was conclu ded that there was close relation between retina and PPR, PPR had less relation to the constriction of the ocular muscles, the components of ERG were included in such early components as PPR1, PPR2, PPR3, PPR4 and that such later components as PPR5 and PPR6 were considered to be the responses which appeared via nervous system in the brain stem.
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