morphine. Electroence-phalographic recordings show that the initial state of arousal induced by peripheral stimulation is replaced by high-amplitude slow-waves and spindles as the state of immobilization develops. The current results suggest that the sensory stimulation leads to excitation of the ascending reticular formation and, via the Centrum medianum and the Nucleus centralis, to activation of the striatal system, resulting in catalepsy. It would thus appear that the reticular formation and the striatum alternate in excercising a control function over the state of arousal. This would be a logical way of limiting over-reaction, which can be demonstrated most simply on the motoric response. It seems justified, therefore, to assume a relationship between catatonic stupor and the immobilization induced by stimulation. This concept is supported by the observation that of all the compounds investigated only clozapine is capable of inhibiting the immobilization in the rat model. Clozapine is a powerful antipsychotic agent with a pronounced inhibitory effect both on the reticular arousal reaction and on the schizophrenic catatonia.

According to Venables the span of psychotic processes extends from a low level of arousal with an increased reactivity toward sensory stimuli to a high level of arousal with a reduced reactivity toward sensory stimuli. The level of arousal and the degree of reactivity, or breadth of attention, are apparently controlled by a regulatory mechanism which increases the threshold for sensory input in threatening situations. Any factor producing an electroencephalographic arousal reaction leads to a narrowing of attention. Underestimation of the size of a given object is an expression of such a reduction in the span of attention. Various authors have found a reduction in size-constancy in schizophrenics, in particular in patients exhibiting a merkedly reduced contact with their environment. A model is described in which a strong sensory stimulus induces a state of immobilization in rats treated with a low dose of morphine. Electroencephalographic recordings show that the initial state of arousal induced by peripheral stimulation is replaced by high-amplitude slow-waves and spindles as the state of immobilization develops. The current results suggest that the sensory stimulation leads to excitation of the ascending reticular formation and via the Centrum medianum and the Nucleus centralis, to activation of the striatal system, resulting in catalepsy. It would thus appear that the reticular formation and the striatum alternate in excercising a control function over the state of arousal. This would be a logical way of limiting over-reaction, which can be demonstrated most simply on the motoric response. It seems justified, therefore, to assume a relationship between catatonic stupor and the immobilization induced by stimulation. This concept is supported by the observation that of all the compounds investigated only clozapine is capable of inhibiting the immobilization in the rat model. Clozapine is a powerful antipsychotic agent with a pronounced inhibitory effect both on the reticular arousal reaction and on the schizophrenic catatonia.

Bei Ratten wurde über 81/2 Stunden alle 10 Sek durch elektrischen Reiz eine Kaudatum-Spindel ausgelöst. Die Dauer der einzelnen Spindeln wurde dem EEG-Bild zugeordnet. Bei statistischer Auswertung ergaben sich 2 Maxima für die Spindeldauer, das eine in der Einschlafphase (Übergangsphase+Spindelphase), das zweite beim Übergang vom Slow-wave-Schlaf zum paradoxen Schlaf.

The results of earlier investigations pointed to a connection between a raised striatal excitability and the catatogenic effect of neuroleptic drugs. This paper describes experiments in which the caudate function in catatonic rats was blocked by means of local application of KCl solution.

A novel method is described for preparing and implanting brain electrode assemblies in rats. A distinct advantage over older methods is the ease with which large series of animals can be prepared, without the risk of brain damage during soldering. The technique, which is adaptable to any electrode pattern and is also suitable for intracerebral injections in unrestricted animals, has been successfully used over a number of years.

The maximal electroshock on mice and rats is a recognized method for screening new compounds for their activity against “grand mal” epilepsy. Frequently, however, compounds which cannot be classed as anti-epileptic agents also exhibit a protective effect. The attempt was made to differentiate between the true anti-epileptic drugs and other “anti-extensors” by recording the electrocorticogram in the rat simultaneously with the transcorneal electroshock. The results showed that the clinically proved anti-epileptic drugs (phenobarbital, phenytoin, phensuximide, primidone, phenacemide, sulthiame, carbamazepen and trimethadione) had no influence on the electrographic convulsive activity in the cortex, even in doses up to 8-fold the ED50. The role of the mesencephalon in the development of motoric convulsions following electroshock is briefly discussed.

Es wurde bei der Ratte die Wirkung von Bulbocapnin auf die durch elektrische Reizung des N. caudatus ausgelösten Spindeln untersucht. Bulbocapnin bewirkt eine Senkung der Reizschwelle für das Auftreten der Caudatusspindeln und eine starke Zunahme ihrer Spannungsamplitude und Dauer. Die Wirkung wird sowohl im N. caudatus selbst, als auch im Kortex beobachtet. Diese verstärkte Erregbarkeit des N. caudatus geht der bekannten kataleptischen Wirkung von Bulbocapnin zeitlich parallel.

The effects of antidepressant drugs on the convulsive excitability of the cortex, thalamus and hippocampus were investigated electro-encephalographically in rabbits.