This study was made to clarify cardiovascular changes which were induced by electric stimulation of paleo-archicortex of rabbits in reference to electrical activities of the central nervous system.
The re sults were as follows.
1) EEG pattern like spike and wave was observed in the cerebral cortex (CC) and in the hippocampus (HPC) during stimulation of the amygdala at 3Hz, while either blood pressure (BP) or heart rate (HR) showed no change.
2) Stimulation of the amygdala at 8Hz produced EEG pattern like recruiting response in CC and HPC, and that reduced BP and HR. There were a few cases of increases in BP.
3) During stimulation of the amygdala at 100Hz, desynchronization pattern was observed in CC and synchronization or desynchronizat ion pattern was observed in HPC. In the cases of increases in BP, synchronization pattern was observed in HPC. On the other hand, in the cases of decreases in BP, synchronization or desynchronization was observed in HPC.
4) It was revealed from the histological study that the stimulation sites whic h produced the reduction in BP and HR concentrated in the nucleus lateralis, centralis and basalis of the amygdala.
5) When the seizure discharges were induced by stimulation of the amygdala, decreases in BP and HR were enhanced, comparing with cases of no seizure discharge. Furthermore, these changes almost continued until the seizure discharge was ceased to observed.
6) It was considered that the decreases in HR during stimula tion of the amygdala were mainly caused by the excitation of vagi and partly caused by the inhibition of the sympathetic nerve activities.
7) I t was considered that the decreases in BP during stimulation of the amygdala were caused by both the decrease in HR and the inhibition of the sympathetic nerve activities. This inhibition was considered to be caused by the impulses passing through the medical forebrain bundle.
8) When BP was elevated by stimulation of the amygdala, common carotid and femoral blood flow increased. These changes were reduced by the administration of phenoxybenzamine.
9) When BP was decreased by stimulation of the amygdala, common c arotid blood flow increased or remained almost unchanged and femoral blood flow decreased in some cases and decreased shortly after the slight increase in others
.10) Stimulation of the septum at 3Hz,8H z and 100Hz, induced decreases in BP in some cases and increases in BP in others.
11) It was revealed from the histological study that the stimulation sites which produced increases in BP concentrated in the lateral-lower portion of the septum, and that the stimulation sites which produced decreases in BP located diffusely in the septum. Based on the above results, relevancy among changes in hemodyn amics induced by stimulation of the paleo-archicortex, defence reaction, playing dead reaction and psychosomatic diseases were discussed.

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Experiments were conducted to clarify the effects of the VL nucleus and pharmacological agents on the M- and H-waves of gastrocnemius and plantar muscle due to stimulation of the tibial nerve of rabbits.
1. Based on the experimental results of various pharmacological actions on the M- and H-waves, it was understood that myanesin and morphine showed inhibitory effect and CDPcholine showed facilitatory effect on the reflex arc of gastrocnemius, and that morphine showed inhibitory effect, CDP-choline, facilitatory effect, and myanesin both facilitatory and inhibitory effect on the reflex arc of plantar muscle, while barbiturate showed no significant effect on the reflex arc of either gastrocnemius or plantar muscle.
2. Stimulation of the brain stem reticular forma tion induced both facilitatory and inhibitory effects on the M-wave of gastrocnemius and plantar muscle, and that induced inhibitory effect on the H-wave.
3. St imulation of VA and raphe nucleus presented inhibitory effect on the M- and H-waves.
4. Contrary to the results of VA and raphe stimulation, VL showed inhibitory effect on the M- and H-waves in some cases, and that showed facilitatory effect in other cases.
5. Since an anatomical difference was noted among the sites of stimulatio n in VL which caused facilitatory or inhibitory effect on the M-- and H-waves, further investigations were made to clarify the effects of the lateral and medial part of VL on various phenomena, respectively.
6. On the arousal reaction and evoked muscular discharges of fore and hind limbs due to stimulation of the brain stem reticular formation, stimulation of both lateral and medial part of VL showed inhibitory effect, and the inhibitory effect was stronger when the lateral part was stimulated.
7. On the evoked muscular discharges of fore and hind limbs due to stimulation of the cerebral cortex, stimulation of the lateral part of VL presented inhibitory effect, while stimulation of the medial part of VL presented both facilitatory and inhibitory effects.
8. On the evoked muscular discharges of fore and hind limbs due to stimulation of the hippocampus, stimulation of the lateral part of VL showed inhibitory effect while stimulation of the medial part of VL showed facilitatory effect. L-DOPA reacted to prevent changes due to such effects, and that indicated a strong inhibitory effect on the facilitatory effect due to medial stimulation, especially to the flexor of the fore limb.
9. Studies on the effects of stimulation of the me dial and lateral part of VL on the Mand H-waves proved inhibitory effect by both stimulation of the lateral part at 3Hz and stimulation of the medial part at 100Hz on H-wave, and facilitatory effect by both stimulati on of the lateral part at 100Hz and stimulation of the medial part at 3Hz. L-DOPA inhibited such effects.
10. Destruction of the lateral part of VL increased the amplitude of the H-wave, while that of the medial part decreased it. L-DOPA showed an action in the direction to eliminate such changes.
11. Besides L-DOPA, effects of ethopropazine on the muscular discharges due to stimulation of the hippocampus and on the M- and H-waves were also studied. The results were as follows. Ethopropazine indicated a similar effect as L-DOPA on the M- and H-waves, but on the muscular discharges due to stimulation of the hippocampus, ethopropazine showed the action to inhibit the facilitatory effect on the muscles except for the fore limb flexor, contrary to the results of L-DOPA.

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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 diazepam
Though 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.

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Studies on the correlation between hyperosmolality and brain damage, especially intracranial hemorrhage (ICH) were carried out on young and newborn rabbits following the infusion of a hypertonic solution ( 7 % sodium bicarbonate).
1) All the young rabbits inject ed with 7 % sodium bicarbonate died of hyperosmolality over 380mOsm/L (mean was 462m0sm/L) after the drip infusion (18--60/d/kg/hr). Young rab bits under 10% hypoxic environment died even at 350mOsm/L level (mean was 397mOsm/L)during the infusion of 7 % sodium bicarbonate. Newborn rabbits injected with 7% sodium bicarbonate 10/d/kg intraperitoneally had ICH in half of the cases at 335mOsm/L. When hyperosmolality reached 392mOsm/L (50mi/kg), ICH could be observed in all cases.
2) The main cause of death in young and newborn rabbits was subdural he morrhage (SDH)in the subtentorial region. Intraventricular hemorrhages (IVH) were observed in about 40% of the cases in the young and newborn rabbits.
3) The blood pH was elevated by the drip infusion, but when hyperosmolality reached about 400mOsm/L, the blood pH began to fall. At the same osmolality, pCO2 showed a ma rked elevation. It is likely that the decrease of the blood pH was caused by the elevation of pCO2and the outflow of H+ from intracellular compartments resulting from hyperosmolality.
4) Electron microscopic observation on the brain capillaries of the above animals revealed shrinkage of the endothelial cells, irregular swelling of the basement membrane and exudation of horseradish peroxidase (HRP) in the perivascular space (neuropil). HRP was detected neither in endfeet of astrocytes nor in nerve cells. This finding was corresponding to the figure of vasogenic edema. The increased permeability of the endothelial cells may depend on the opening of the tight junction caused by hyperosmolality and the pinocytotic vesicular transport in the cases of the hypoxic group.
These results appar ently indicate that fatal ICH accompanied with brain edema was induced by hyperosmolality and was enhanced by the combination of hypoxia and immaturity.

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