Effect on Brain Enzyme and Behaviour in the Rat of Visual Pattern Restriction in Early Life

Abstract

SEVERAL studies have shown that certain behavioural and biochemical changes can be produced in rats if they are raised in an “enriched environment” or subjected to stress or handling during infancy¹. Typically, an enriched environment is created by placing some small objects or mates in the cage of the animal or by handling the animal every day for a specified period of time. All these manipulations require an extended period of physical contact either with other animals, with the experimenter or with both. When animals are handled or permitted to live together, the resulting temperature differential alone can produce physiological changes², so it is not clear whether some behavioural or physiological changes can be produced in an adult animal by manipulating just the visual or auditory environment in infancy. By eliminating group living and handling, and manipulating only the visual complexity of the environment in which rats were raised, we found significant differences in body weight, brain cholinesterase (ChE) activity and sensory conditioning.