Effects of exposure conditions to spontaneous locomotor activity footshocks early in life on at maturity in rats

Both genetic and environmental factors are involved in establishing a behav ior. An animal study was done to determine the characteristics of interacti on between genetic (nature) and environmental (nurture) factors. Delivery o f footshocks (0.8 mA x 60 times, at random) early in life was used as the e nvironmental stimulus. As the footshock was delivered repeatedly, a rat sho wed helplessness behavior and the number of shocks necessary to elicit help lessness was measured to quantify the trait of an animal in coping with the aversive environmental stimulus. The nocturnal ambulatory activity at adul thood was measured as a behavioral expression of the nature-nurture interac tion. Although the experience of footshocks early in life did not significa ntly alter average activity levels at adulthood, the activity was positivel y correlated with the number of shocks necessary to elicit helplessness (na ture) while receiving footshocks (nurture) on postnatal day 14. Additionall y, a second exposure to identical shock; parameters on postnatal day 21 rev ersed the relationship. These results clearly showed that an interaction be tween nature and nurture during infancy leads to substantial behavioral alt erations later in life, and suggest thar the nature-dependent determination of an adult behavior can be modified in different directions by the condit ions of an environmental experience early in life.