Efeito da estimulação transcraniana cerebelar por corrente contínua na aprendizagem de tarefas de sequência e adaptação motora em pessoas com paralisia cerebral

Abstract

Transcranial direct current stimulation (tDCS) is considered a promising tool for neurorehabilitation. When applied to the cerebellum, tDCS has shown positive effects on the acquisition and consolidation of motor skills in healthy adults. In individuals with cerebral palsy (CP), tDCS combined with motor training has shown promising results in outcomes such as manual function, gait, mobility, and balance. These individuals exhibit changes in cortical excitability and deficits in motor learning, a complex process that can be influenced by various factors, including the nature of the task. Tasks can be divided into two main categories: motor adaptation and motor sequence. Motor adaptation tasks involve adjustments in response to environmental changes and tend to recruit the cerebellum more as learning progresses. On the other hand, motor sequence tasks, which involve the progressive coordination of movement elements, rely more on structures such as the striatum during the automatic phase of performance. This study aimed to evaluate the effect of cerebellar tDCS on the learning of motor adaptation and motor sequence tasks in individuals with CP. The study involved 20 individuals with spastic CP, aged between 8 and 20 years (average age of 14 years), of both genders (57% male), and inexperienced in the tasks. The study was divided into two experiments, conducted one month apart. Participants were randomly allocated into four experimental groups and performed motor practice associated with tDCS or its placebo. After one month, 18 participants were redistributed into new groups and performed the motor task they had not yet executed. In the motor sequence task, participants were instructed to type a sequence of keys on an adapted keyboard as quickly as possible after the initial presentation on the monitor. In the motor adaptation task, information about the keys appeared one by one, without prior knowledge of the complete sequence. Participants practiced 100 attempts of the motor task, and measures of reaction time, movement time, and response time in blocks of trials were analyzed. The results showed that the group that underwent cerebellar tDCS associated with the motor adaptation task showed a significant improvement in reaction time during the online change, movement time during the offline change, and response time from the pre-test to the post-test block, compared to the control group, which improved reaction time from the end of the acquisition phase to the post-test. In contrast, the group that performed tDCS associated with motor sequence task practice demonstrated poorer performance in reaction time, movement time, and response time during the acquisition blocks, compared to the control group. The results suggest that anodal cerebellar tDCS may improve specific aspects of learning in motor adaptation tasks. However, the data indicate that this stimulation may have negative effects on the acquisition phase of motor sequence tasks.