Body temperature as a determinant in maze acquisition by mice

¹ Departments of Physiology and Rehabilitation Medicine, Albert Einstein College of Medicine, New York City

The effect of increasing the number of training trials and spacing training sessions on acquisition of a simple water-escape response was investigated in mice during a moderate reduction in colonic temperature. Hypothermia was produced by treatment of the animals with 50 mg/kg 2,4-dichlorophenoxyacetic acid (2,4-D) (i.p.) and a 30-min exposure to cold air (2.0 ± 0.5 C). Control animals received 2,4-D and were maintained in a thermoneutral environment (32.0 ± 1 C) to preclude loss of body temperature. Following these procedures, all animals were given four training trials spaced at 15-min intervals. Two days later, the procedures were repeated and four more training trials were given. Acquisition of the escape response occurred within five training trials for animals in which colonic temperatures were reduced 2.6–4.8 C during training. Control animals demonstrated acquisition of the maze habit within two training trials. These data suggest that extending the training trials over an expanded period of time was effective in allowing for acquisition in hypothermic mice and that a reduction in body temperature affects acquisition rate.

Submitted on March 6, 1963