Dissociation of a phenotypic correlation: Response to post-trial etherization and to variation in temporal distribution of practice trials

Abstract

We reported previously (1) that mice of strain DBA/2J show superior performance on both an active and a passive learning task when trials are massed, while mice of strain C57BL/6J show superior performance on both tasks when trials are distributed and (2) that post-trial etherization can result in facilitation of learning performance of mice of strain DBA/2J but not of strain C57BL/6J. We further suggested that there might be a high functional relation between differences in performance under massed and distributed temporal conditions of practice and response to etherization. Specifically, we suggested that superiority under massed practice is associated with a facilitative response to post-trial etherization, while superiority under distributed practice is associated with lack of a facilitative response to etherization. This paper reports studies of the learning performances of two new strains, BDP/J and SJL/J, with massed and distributed trials and studies of the effects of etherization on, performance of these two strains for tasks on which they are superior under the distributed-practice condition. The possible relation of lack of ether facilitation to superior performance under the distributed-practice condition was not confirmed.