Effects of Insulin, Metrazol, and Electroconvulsive Shocks upon Learning to Learn 30 Successive Reversal Problems by Rats

Abstract

To determine the relative effects of insulin, metrazol and electroconvulsive shocks upon learning to learn 30 successive reversal problems by rats, an enclosed square T-maze was used, with water as incentive after 23 hr. of deprivation. S had to achieve 9 correct out of 10 daily trials before a problem was reversed. 40 adult male rats were equally divided into a control and 3 differently shocked groups. Shocks were administered on 3 alternate days followed by 2 days of rest. Each time, Ss of the 4 groups received respectively 0.5 cc. of saline, 55 mg. of metrazol per kg. of body-weight, one unit of insulin per 20 gm. of body-weight, and an electric current of 50 ma. at 25 v for 150 msec. Convulsion in the insulin group was prevented by an injection of dextrose and potassium chloride. The control was significantly superior to the 3 shocked groups which were remarkably similar or practically identical in their performance during the initial 6 problems. Thereafter, both the non-convulsive (saline and insulin) groups did better than the 2 convulsive groups either in terms of error, day, or one-trial reversal score.