NEUROLOGICAL AND ELECTROENCEPHALOGRAPHIC EFFECTS OF X-IRRADIATION OF THE HEAD IN MONKEYS

THE ADULT nervous system is highly resistant to ionizing radiation at dosage levels which severely injure other tissues.* In support of this generalization Eldred and Trowbridge have recently found that x-irradiation of monkeys with totalbody doses of 400 to 800 r failed to induce neurological changes, 3 although radiation sickness and death occurred. 4 It has been shown, however, that higher doses of radiation, when restricted to the heads of monkeys, may result in weakness, apathy, hemiparesis, and hemiplegia. 5 Similarly, tremors, clonic twitching, and epileptoid seizures have been seen after irradiation of the brains of puppies.† Lyman, Kupalov, and Scholz 8 and Nemenov ‡ believed that irradiation of the head in dogs caused impairment of reflex conditioning (Pavlov), while Warren 10 reported a "depression" of the nervous system in rats after 1,500 r total-body exposure. These investigations, together with case reports in man,s indicate that the central nervous system