Caudate Nucleus Stimulation Retroactively Impairs Complex Maze Learning in the Rat

Rats, with permanent electrodes implanted bilaterally in the caudateputamen complex, were stimulated with single pulses after reinforcement of each maze learning trial or were stimulated with multiple pulses after each choice point or after reinforcement. Single pulses retarded the development of learning only when stringent learning criteria were required, whereas multiple pulses interfered with acquisition when the criteria for learning were less difficult.