The ChE activity of cerebral cortex resected from idiopathic epileptics and non-epilcptics and the influences of glutamic acid, glutamine, aspartic acid, asparagine, γ-aminobutyric acid and γ-amino-β-hydrooxybutyric acid were studied. 1) In the brain of idiopathic epileptics, ChE activity is more markedly accelerated than that in the brain of non-epileptics. 2) By adding the amino-acids mentioned above, restraint occurs in each case. The intensity of these restraint for the non-epilcptic brain has the order of asparagine, glutamine, γ-amino-β-hydroxybutyric acid, glutamic acid, aspartic acid, glutamine. γ-aminobutyric acid, while that for idiopathic epileptic brain it is asparagine, aspartic acid, glutamine, γ-amino-β-hydroxybutyric acid, glutamic acid γ-aminobutyric acid. 3) The reduction of ChE activity by adding amino acids is found in each case of epileptic and non-epileptic brain. But it is not so definite in epileptic brain as in none-epileptic brain.
4) The ascending of ChE activity in idiopathic epileptic brain is regarded to be caused by the reduction of free amino acids in idiopathic brain.