Factors modulating the effects of teleost telencephalon ablation on retention, relearning, and extinction of...

Two experiments on the nature of avoidance behavior in the goldfish are reported. In the first experiment, a master/yoked design was used to determine the degree to which Pavlovian conditioning would generate acquisition of a shuttle response by goldfish. Results indicated that the mere sequence of signal-shock pairings experienced by the avoidance animals is not in this situation sufficient to explain the development of the instrumental avoidance responding. The second experiment was conducted to study the effects of three variables on the retention and extinction of the avoidance response. First, unilateral lesions of the telencephalon produced a transient deficit from which the subjects recovered to normal levels. Retention of the avoidance response after bilateral telencephalon ablation was impaired and never fully recovered with additional training. Second, this deficit was reduced under higher intensities of electric shock. Third, overtraining on the task before the ablation had only a nonsignificant enhancing effect on retention levels. Extinction was always poorer following ablation, independent of the type of ablation, intensity of shock, degree of overtraining, and terminal retention level of performance. The results are discussed in terms of various theories of telencephalic function in fish.