Differential rearing conditions in rats: effects on neurochemistry in neocortical areas and cognitive behaviors.

Previous studies have shown that environmental factors can influence several aspects of the central nervous system that are associated with behavioral changes. In the present study, an attempt was made to investigate how cholinergic and glutamergic transmission systems in neocortical areas might respond to differential rearing conditions and how potential neurochemical changes might be accompanied by alterations in behavior. The results show that only glutamergic levels in the lateral entorhinal cortex (LEC) responded to differential environmental stimulation. The levels of glutamergic activity in LEC correlated significantly with learning and retention of a visual discrimination task and total time exploring objects in a novelty test. A comparatively complex pattern of neurochemical relations was seen in terms of differences across brain structures and hemispheres for both glutamergic and cholinergic activity. The results are interpreted as supporting the glutamergic hypothesis of Alzheimer's disease.