Short CommunicationEffect of catechol-O-methyltransferase-val158met-polymorphism on the automatization of motor skills - A post hoc view on an experimental data

- We analyzed the COMT-genotype of 22 participants who practiced a motor task.
- Participants were tested with a dual-task paradigm in a pre-post design.
- The number of met-alleles was positively correlated with dual-task cost reduction.
- The reduction in dual-task costs is referred to motor automatization.
- The effect of COMT-genotype on dopamine dependent reward processing is discussed.

The purpose of this study was to evaluate if the catechol-O-methyltransferase-val158met (COMT)-polymorphism, which is known to affect prefrontal dopaminergic metabolism, affects the automatization of motor skills. Twenty-two participants volunteered for gene analysis after they had participated in experiments in which they practiced a single-joint arm movement sequence 460-760 times under different feedback conditions. Motor automaticity was assessed in a pre-test and a post-test according to the dual-task paradigm, which incorporated a visuo-spatial secondary task. To account for the different practice conditions in the four original studies, dual-task cost reduction was assessed using single case effect sizes proportioned to the respective group mean. For the secondary task but not for the prioritized motor task, these relative single case effect sizes proved to be positively (and significantly) correlated with the number of met-alleles on the COMT-genotype, rs = .553; p = .004. Thus, the number of met-alleles indicated a tendency toward enhanced motor automatization. Thus, due to an increased prefrontal dopamine level, met-carriers may be able to develop a well formed and stable, spatially coded movement representation early in practice, thereby supporting the formation of a representation in motor coordinates in the course of extended practice, which later enables automatic movement execution. This process might also be enhanced by a prevalence of met-carriers to functionally evaluate positive feedback information (i.e., rewards) and to better maintain recent reward information in active working memory.