The effect of metrazol injections on the electroencephalogram

Abstract

1. The electrical potentials arising from the head after metrazol injection have been recorded. On the basis of a comparison of the potentials recorded from leads taken at various locations on the head, with electromyograms and with the movements as shown by ultra-highspeed motion pictures, an attempt has been made to separate the brain potentials from potentials caused by movement and muscle action currents. 2. The overt seizure shows in all stages, from the latent period to the end of the second clonic stage, an activity of 30 cycles per second in the motor region. An activity of 10 cycles per second was recorded from occipital leads during the latent period and the tonic stage. Motor-occipital leads recorded in the latent period showed some activity of 15 to 16 and 3 to 5 cycles per second. 3. The relaxation period shows low-voltage random activity. 4. If no seizure follows the metrazol injection the following changes in the EEG may occur: a. Drop in percent-time alpha without appearance of abnormal potentials and return to normal activity within a minute. b. Appearance of random abnormal potentials with a slow return to normal activity after more than 45 minutes. c. Larval seizure after which the activity returns to normal in less than 15 minutes. The importance of this type of reaction to the theory of epilepsy has been discussed.