386 TAKASHl HAYASHI 



(2) the substance accelerates the production of the real excitatory 

 transmitter; or 



(3) it inhibits the production of the anti-substance of the excitatory 

 transmitter in the brain. 



As for INH, OMP and curare, as well as semicarbazide and hydroxylamine 

 they were found to belong to the last category mentioned above (3). We 

 found the convulsants which belonged to the above category (2) to be guani- 

 dine or methylene blue, while GABA was found to belong to category (1). 

 As shown in Table 2, when GABA was introduced into the ventricle of dogs, 



Table 2. The critical dosage to produce seizure 



IN DOGS 



it produced a seizure in one case out of twenty experiments. But we found that 

 when vitamins B12 and Bi accompanied GABA it produced seizures in twenty 

 cases out of twenty. Here GABA was changed into some unknown factor 

 which acted to produce generahzed seizure. The normal brain contains GABA 

 in the concentration of 0-031 % and it has been argued that GABA might be 

 the mother substance of both the excitatory and the inhibitory transmitter in 

 higher animals (Hayashi, 1959). 



