Abstract
A suppressing effect of γ-aminobutyric acid (GAB) upon cortically or reflexly induced movements was studied with cats by injecting the substance intracisternally in amount less than 10mg.
1. Cortically induced movements due to strychninization or electrostimulation of the motor cortex were arrested by GAB within a short time. At this time there could not be found any noticeable changes of electrical activity in the motor cortex which was the impulse origin of the suppressed motor response.
2. A suppression of spinal reflexes was obtained by administrating GAB. It was associated with a suppression of the cortically induced movement and spontaneous shivering. The reflex suppression was found to occur in decerebrate cats as well, when GAB was sprayed around the cut end of the brain stem.
3. When the spinal cord was transected acutely, the reflex activity of the isolated spinal segments escaped the suppressing effect of GAB.
4. It was found in some cases that EEG synchronization was caused by GAB in association with the reflex suppression.
5. Concerning the site of action of GAB, a supposition was made that the motor suppression due to GAB might be the result of an inhibition of the reticular facilitatory system of the brain stem.
The authors are indebted to Dr. Tomoaki Asano for his invaluable suggestions in regard to preparing the manuscript. A part of the expense for this work was defrayed by a grant of the Ministry of Education.
