Hyperemotionality manifested by violent attack or flight reactions in response to previous neutral or innocuous stimuli, has been observed in rats with lesions of the septal area of the brain (hereinafter referred to as "septal rats") (1-4). The hyperemotionality of septal rats was restored to normal by making other lesions in the amygdaloid or administering certain tranquilizing drugs (2, 4-7). From these observations, it was possible to assume that the limbic system exerted an important function in the "physio logical tranquilization" of rats and that tranquilizing drugs might have an effect on this part of the brain.It has recently been reported that rats in which the olfactory bulb had been removed (hereinafter referred to as "O.B.-rats") exerted hyperemotionality similar to that of the septal rats (14, 18), and this hyperemotionality of O.B.-rats was also corrected by making other lesions in the amygdaloid (8).In this report, change in emotional behavior of O.B.-rats was analyzed using the scoring method and the effect of various psychotherapeutic drugs on the hyperemotion ality of these animals was observed. The effects of these drugs are compared with the general activity of normal rats and the taming effect of these drugs is also discussed herein. METHODS 1) Animals and surgical procedureMale albino rats of the Wistar strain each weighing 250-350 g were used. The ani mals were anesthetized with 50 mg/kg of sodium pentobarbital given intraperitoneally and held in a stereotaxic instrument. After a suitable hole bored in the skull with a tre phine, the dura was opened and the olfactory bulb was removed by suction as completely as possible. Sham operation was performed by the same procedure on the same area of the skull. These animals were placed in individual cages with free access to water and food. At the end of the experimental period, the brain of each rat was fixed in 10 per cent formalin solution and sectioned to confirm the correct placement of the lesion.

The unitary discharges of respiratory neurones were recorded in the cats. Cats were immobilized with gallamine triethiodide under artificial respiration, or anesthetized with pentobarbital. Spontane ous and rhythmic unit discharges in the brainstem corresponding to the periodicity of phrenic nerve discharges were recorded ( Fig. 1-C). In the lateral medullary reticular formation the ratio of inspi ratory : expiratory units were approximately 3.3 : 1 under pentobarbital anesthesia. However, in curarized cats there were 1.7 : 1. In the pontine reticular formation the respiratory discharges were not detected in the case of pentobarbital anesthesia ( Fig. 1-A), but in curarized and bilaterally vago

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The respiratory rhythmic activity is originated in the brainstem, although the afferent impulses are modifying the pattern of the respiration by changing the duration and/or frequency.However, it is not conclusively decided which part of the brainstem is responsible intrinsically for the forma tion of the rhythmic activity. Therefore, the experiments to compare the unit activity in the medulla before and after the isolation of the medulla were undertaken. The inspiratory as well as expiratory unit discharges in the lateral medullary reticular formation were simultaneously recorded using a microelectrode in the cats which were immobilized with gallamine triethiodide under artificial re spiration. During the recording of the discharges, the medulla was isolated by the following proce dures : cutting the vagi and the sinus nerves ( Fig. 1-2), brainstem transection between the pons and the medulla and spinal cord transection between Cs and C,. After these procedures the patterns of the discharges were changed in their frequency and duration, but the rhythmic activity remained ( Fig. 1-3). These results indicate that the respiratory neuronal activity in the lateral medullary reticular formation is primarily responsible for the formation of the respiratory rhythmic activity.FIG.

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