Developmental environment: variables important for later learning and changes in cholinergic activity

Environmental experience of developing rats was manipulated in two ways. These were (1) providing increments in amount of visual stimulation vs. increased variety of novelty of visual stimulation, and (2) informal experience vs. formal training in discriminating between the given stimuli. At the conclusion of the developmental treatment an index of performance change was obtained by testing discrimination learning on a Lashley Jumping Stand. Effects on the cholinergic system, specifically, acetylcholinesterase (AChE) and cholinesterase (ChE) activities, were also examined. Increments in variety of stimulation, but not increases in amount, were found to contribute significantly to observed differences in AChE and ChE activity and in learning performance. Formal training in addition to enriched informal experience added little to either the biochemical effects or to the observed improvement in performance on the relevant learning task.