Effects of intracerebrally injected physiological solution, normal rabbit gammaglobulin and rabbit anti-monkey liver, anti-hippocampus and anti-caudate nucleus gamma-globulins on spontaneous and evoked electrical activity of hippocampus and caudate nucleus were investigated in rhesus monkeys.

Microinjection of physiological solution did not produce essential modifications of electrical activity.

Normal and anti-liver GGs induced considerable and progressive decrease of the amplitude and slowing down of electrical activity of the hippocampus and caudate nucleus. The effect was reversible, and 2–3 weeks after the injection had been discontinued the electrical activity resumed its preinjection appearance. The depression caused by anti-liver GG seemed to be more marked.

Anti-hippocampal and anti-caudate nucleus GGs, when injected into homologous structures, caused the appearance of highly irritative EEG abnormalities ultimately developing in self-sustained epileptiform seizures which, in the case of hippocampus, could occasionally be seen even a month after the injection of anti-hippocampal GG was terminated. The end of convulsions was followed by a period of profound depression, preceding gradual recovery and restoration of spontaneous electrical activity within about a month after the beginning of the experiment.

Modifications of thresholds and durations of electrically evoked hippocampal after-discharges fairly well corroborated the above-described findings.