[Genetically determined variability in rat behavior and its biochemical correlates].

Using the combination of extremely high and low values of two independent behavioural variables (activity and frequency of defecation in open field) four groups of rats were selected with different CNS reactivity corresponding to the types of higher nervous activity described by I.P. Pavlov. These groups of rats revealed significant differences in reactivity to stress and drugs, in social behaviour and biochemical pattern. They may represent a useful tool for the research in experimental psychology, neurophysiology, psychopharmacology and other branches of science.