Lateralization of Motor Functions in Early Human Ontogeny

This study was aimed at testing the hypothesis about the development of lateralization of frontal motor control (FMC) as a source of preference of the right hand human in early ontogeny. The sample consisted of 108 children aged from 8 months (the initial stage of maturation of inhibitory control in reaching) to 11 months (the definitive stage). The main results showed the following: (1) at the population level, the preference of the right hand in the performance of tests that require a definite level of development of FMC appears only at the age of 11 months, i.e., synchronously with development of frontal inhibitory control of reaching; (2) the preference of the right hand is substantially stronger in 11-month-old children with a higher level of development of inhibitory motor control as compared to other children of the same age; (3) the preference of the right hand is most evident for those movements that require inhibitory control (i.e., controlled reaching). On the whole, the data obtained show that the appearance of a preference for the right hand in the second half-year of the life of an infant is caused by the development of cortical inhibitory control over motor acts (FMC), associated with the maturation of the frontal neocortex.