[Nature of functional motor asymmetry in animals: state of the problem]

Handedness in skilled movements of animals is a result of interaction of innate motor preference and learning. The nature of the innate preference is not clear. Breeding of right-handed and left-handed mice revealed that the degree rather than direction of motor preference is an inherited feature. There is, however, a correlation between the direction of preference and a number of morphological, functional, and neurochemical characters. Shifts of a preference direction were found in some strains of mice. Differences between right-handed and left-handed rats were revealed in social behavior, learning, and resistance to forced retraining. Strains of rats with different forms of genetic epilepsy were characterized by the predominance of animals with a certain direction of the motor preference. This evidence suggests some genetic influence on a direction of the motor preference. Perhaps, genetic and environmental factors closely interact in determining motor preference in animals.