EFFECTS OF CROSS-FOSTERING ON AVOIDANCE LEARNING AND FREEZING BEHAVIOR OF DBA2J AND C3H/HE INBRED MICE

The effects of cross-fostering were assessed on two inbred strains of mice (DBA2J and C3H/He) characterized by sharp discrepancies in learning curves and memory patterns when trained in a shuttle-box. The data show that modifications of preweaning environment affect the emotional behavior while variations of learning patterns are only due to the concomitant appearance of freezing behavior. In the most general terms these findings support the hypothesis that non genetic factors can also contribute to the development of strains-specific patterns of behavior. © 1968.