[Escape-avoidance learning in two strains of inbred mice when two types of response can be alternatively effective]

Three experiments demonstrated that escape-avoidance learning is closely related to the response type dominantly occurred in mice of an inbred strain. Inescapable shock elicited locomotion (L-typed response) in C57BL/6 mice, and rearing or jumping (R-typed response) in C3H/He (Experiment 1). In the shuttle-box situation where both of these responses can be effective to terminate CS tone and electric shock, C57BL established L-typed avoidance mainly, while C3H tended to learn avoidance by R-typed response (Experiment 2). The two strains learned the escape in the shuttle-box by the same types of response as they showed in avoidance learning (Experiment 3). These findings lead us to conclude that different inbred strains of mice innately react to electric shock by their specific types of response. Strain differences in escape-avoidance learning could thus be attributed to the compatibility of the specific response type with requirement of the task situation.