Role of BDNF genetic variations in motor skill acquisition: a pilot study

Abstract

Background: Motor learning induces neural plasticity which ismodulated primarily byBrain-DerivedNeurotrophic Factor (BDNF). Recent studies have shown that BDNF Val66Met polymorphism influences learning of a visualmotor tracking task and the neural changes associated to it. This polymorphism has also been shown to affect stroke outcomes. However, there are no studies that have examined the role of this polymorphism in the learning of a sequential motor task which engages different sets of processes from those of the tracking task. Purpose: The purpose of this study was to determine the role of BDNF genetic variation in learning of a finger sequence movement. We hypothesized that individuals with Val66Met polymorphismwould show inferior learning of the task compared to those without. Methods: 40 young healthy adults (mean age = 23.9 years old) were recruited. Buccal swap sample was collected and genotype was determined by using Taqman SNP genotyping assay (rs6265). The participants then practiced a 4-element finger sequence task with their dominant hand for 144 trials. The participants were instructed to improve the task performance by reducing the time required to finish the sequence (movement time). Learning of the task was evaluated on the next day, approximately 24 hours later, with a delayed retention test. The tester was blinded to the genotype of participants. The genotyping results were revealed after all the behavioural task data were collected and analyzed. The data were then divided into two groups (val66met carriers vs. non-carriers). We used two-way repeated measure ANOVA and independent t-test to compare the task performance and learning between the two groups. Results: 24 out of the 40 participants were val66met carriers (60%). Both groups (val66met carriers and non-carriers) showed improved movement time during the training phase (p= .04). There was a significant group by practice effect (p= .047) with the val66met carriers showed a greater change in movement time than the non-carriers. However, there was no difference noted in the index of learning (forgetting) between the groups (p= .56). Conclusion(s):Thefindings suggest that BDNFpolymorphism may not influence learning of a motor sequence task. However, the extensive practice in the present studymay have affected the effect of BDNFpolymorphism onmotor learning as a previous report showed that extensive practice may overcome the deficits in learning among the met allele carriers. Further investigation on the relationship between the amount of practice and polymorphism influence on motor learning is being conducted. Implications: Understanding the relationship between genetic variations andmotor learningwill aid to identify those who might require tailored program during motor rehabilitation.