THE INHIBITORY SUBSTANCE EXTRACTED FROM BRAIN 371 



Fig. 1. Paper chromatogram of the brain extract. Left stripes indicate the GABA 

 and picrate positive area, right ones the position of standard GABA and GABOB. 



brain resulted in marked decrease of excitability, the same eflfect could not be 

 obtained with GABA or GABOB. 



(c) By means of recording the electrical activity of the cat's cortex, we 

 examined the effects of local and systemic administration of the brain extract, 

 and those of GABA and GABOB on strychnine and metrazol convulsions. 

 The recordings were made under barbiturate (Evipan-Na) or ether anaes- 

 thesia, or in succinylchohne paralysis with artificial respiration in the waking 

 state. Our observations may be summarized as follows. 



(1) Under barbiturate anaesthesia not even high concentrations of the brain 

 extract, GABA or GABOB, administered either locally or intravenously, 

 resulted in a noteworthy effect on the electrical activity of the somatomotor 

 cortex, recorded with bipolar "ball-electrodes" of silver. Under superficial 

 ether anaesthesia, or in succinylcholine paralysis in the waking state, local as 

 well as intravenous administration of the extract from one-third to a half of 

 a dog's brain tissue, resulted in decreased frequency and increased amplitude, 

 which, however, was of a transitory nature. Even larger doses of GABA or 

 GABOB failed to produce an effect worth mentioning. During inetrazol 

 convulsion produced by the intravenous administration of Tetracor, con- 

 vulsive activity was considerably decreased, or in the case of smaller doses of 

 Metrazol, inhibited by the extract from a half to one dog's brain given a few 

 seconds before Tetracor. 



On the basis of Figs. 2 and 3 it can be seen that during or immediately 



