text: Relative effects of scopolamine and electroconvulsive shock upon habit reversal in white rats.
  30 adult male white rats were equally divided into control, scopolamine, and electroconvulsive shock groups to learn 20 successive reversal problems in an E-maze for water after 23 1/2 hr. of deprivation. The noncorrection method was used. After 1 mo. of preliminary training, each scopolamine animal received an intraperitoneal injection of 1 mgm of scopolamine hydrobromide per kgm of body weight while each in the shock group was given an ECS of 35 mA for .2 sec. at the end of every 10 daily trials. When a rat obtained 9 correct of 10 trials, the goal was switched to the opposite side of the maze. Controls were much superior to both experimental groups. While scopolamine animals experienced more detrimental effects initially, they caught up with the shock group and finally became superior. This shift is interpreted in terms of building tolerance to scopolamine and increasing anxiety to shock as effects of differential treatments accumulated.