Castration and Ovariectomy on Spontaneous Activity and Ability to Learn. ∗

Abstract

The present investigation is directed toward the establishment of the relationship between spontaneous activity and the ability to learn, with special reference to castration and ovariectomy, on these processes. This is a preliminary report of the first experiment undertaken to establish the relationship mentioned above.

Data were collected from 5 litters containing 35 rats under 50 days of age. The ability of each rat to learn was measured by means of a maze described by Rickey. 1 Spontaneous activity was determined by the revolving cage method described by Durrant. 2 Fifteen animals were operated in an attempt to modify their activity, while 20 were used as controls. Data were collected with reference to the number of trials required to learn the maze and the number of errors made in so doing. The learning time was recorded in seconds and the spontaneous activity in number of revolutions. Table I shows the data collected up to the present time. The figures presented under “activity” represent the average daily number of revolutions run over a period of 10 days.

The data in Table I reveal the fact that in case of litters 1 and 2, castration had no effect on either the learning process or spontaneous activity. They show also that in litter 4, the castrates had a distinct advantage over the normals in all parts of the experiment. In litters 3 and 5, just the reverse is true since the normals have the advantage.

Although the data in Table I indicate that there is a relationship between spontaneous activity and learning, this point is shown to a better advantage in Table 11. Here, in each litter the individual rats are ranked according to their speed in learning the maze.