ELECTROENCEPHALOGRAPHIC STUDIES ON FATIGUE INDUCED BY ENFORCED SWIMMING IN THE WHITE RAT

1. Changes in the cerebral functional state were studied electroencephalographically in fatigue induced by forced swimming of 13 rats.2. The characteristic changes of the EEG's in fatigued rats were the suppression of the basic waves and increase of the small fast waves, which indicate an enhanced state of cerebral excitatory level and considered to be an excited period of fatigue (Type 1).3. Both the average frequency and amplitude increased in one rat in the fatigued state, and indicate a higher excitatory level than type 1 (Type 2).4. Slow waves appeared in the recovery stage in one rat, and indicated a drowsy state or lowered level in cerebral excitation and is considered to be an inhibited state of fatigue (Type 3).5. It has already been shown by us that the excited period was generally followed by an inhibited period in mental fatigue, but only an excited state of the brain was found in somatic fatigue, even though the animal was thought to be extremely fatigued, except for one case in the recovery stage.