Efeitos da estimulação transcraniana por corrente contínua na transferência bilateral de aprendizagem

Abstract

Bilateral transfer of learning (TBA) refers to the ability to learn a new skill more easily with one limb after that skill has been learned by the opposite limb. One of the propositions points out that TBA occurs due to the existing inter-hemispheric communication between the two cerebral hemispheres, which guarantees the transfer of learning from one member to the other. Through the use of transcranial direct current stimulation (tDCS) it is possible to alter the interhemispheric communication. Therefore, the present study aims to investigate the effects of tDCS on TBA in right-handed individuals. The study included 48 right-handed volunteers, aged between 18 and 40 years, who were divided into three groups of 16 volunteers each: MD-tDCS group that received tDCS and performed the acquisition phase with the right hand. ME-tDCS group that received tDCS and performed the acquisition phase with the left hand. Finally, the PL group was counterbalanced between the two previous conditions in relation to the hand that performed the acquisition phase and did not receive tDCS. The Serial Reaction Time Task was applied, which consists of pressing the fastest and most accurate possible sequence of keys: “D, A, F, S” on a standard keyboard. The experiment consisted of three phases: pre-test, acquisition phase and post-test. In the pre-test, the sequence was performed with the right (MD) and left (ME) hands and 16 trials were performed with each hand. Before the acquisition phase, the tDCS denominated groups received tDCS for 20 minutes, while the PL group (placebo) received the stimulation only in the initial 36 seconds. In the acquisition phase, 96 attempts were made with only one hand. Approximately 24 hours after the acquisition phase, the post-test was conducted in which the volunteers again performed 16 attempts with each hand. The analyzed variables were: total time and bilateral learning transfer rate. Regarding the total time variable, in the MD post-test, the DM of the MD-tDCS group differed significantly from the MD of the PL group. In the ME post-test, the ME of the ME-ETCC group differed significantly from the ME of the PL group. There was no group that had a higher TBA index. It was hypothesized that the groups receiving tDCS would have a higher rate of TBA than the PL group. Therefore, the hypothesis raised was not confirmed, as the groups that received tDCS did not show higher TBA rates in relation to the PL group. However, tDCS seems to have influenced the improvement in motor performance related to the total time variable, considering that the groups that received tDCS showed better performance. Finally, it is concluded that the effects of tDCS on TBA and motor performance still require further investigations to be understood. Different tDCS protocols and tasks may contribute to further investigation of its effects on TBA.