Effects of the thyroid gland upon the behaviour and learning ability of rats

Abstract

As the thyroid gland, as any other endocrine organs, is responsible for the mental as well as the bodily development, it has, been advocated by E. Kretschmer, G. Ewald, W. Jaensch, M. R. Berman, O. Klieneberger and other psychologists and characteologists that the thyroid has a great effect upon the human character. Above all, Berman insisted in his The Glands Regulating Personality upon that the thyroid internal secretion has a very definite controlling relation to intelligence and the complexity of the convolutions of the brain, and that when the chemical reactions which depend upon the thyroid go faster, more oxygen and food materials are burned up or oxidized, more energy is liberated, the metabolic wheel rotates More quickly, the individual senses, feels, thinks and acts more quickly. But his theory is imaginative and speculative, lacks the exact psychological experimental ground. We began this study for the purpose of detecting the effect of the thyroid gland upon the behaviour and learning ability of animals. For this purpose, we used 32 albino rats and 12 mice and we sorted them into pairs of the same breeding according to their age, sex and weight—one group for experimental and the other for control animals. To an experimental albino rat, we administered the desiccated thyroid gland every day successively 0.005 gm. per 100 gm. of its bodily weight and to an experimental mouse 0.0006 gm. for some days. Then after about ten days, we experimented on the albino rats by the Obstruction Method, the Maze Learning Method, the Choice Box Method and on the mice by the Revolving Wheel Method. The results of the observations and experiments are as follows. © 1936, The Japanese Psychological Association. All rights reserved.