A big role for the little brain: Investigating sequence learning in the cerebellum using transcranial direct current stimulation and neuroimaging

In recent years, there has been substantial evidence suggesting the involvement of the cerebellum in recognizing sequences based on previous experience, and using this information to create internal models which predict future outcomes. While most research into sequence learning has focused on investigating the motor domain, the question of the involvement of the cerebellum across other domains, such as the perceptual domain, remains yet unexplored. To elucidate the role of the cerebellum in perceptual sequence learning we will combine behavioural experiments, using an implicit sequence learning picture task, with transcranial direct current stimulation (tDCS) and functional magnetic resonance imaging (fMRI). In a behavioural pilot study using the sequence picture task we demonstrated that participants implicitly learned a series of picture sequences. Presently, we will investigate the behavioural effects of cerebellar tDCS on perceptual sequence learning by administering anodal, cathodal and sham cerebellar tDCS (2 mA, 30 minutes each) during the sequence learning task, in a counterbalanced within-subjects design (n = 30). In a second study, we will carry out concurrent tDCS/fMRI experiments with the same task, also in a within-subjects design. Dynamic causal modelling (DCM) will be used to study the interconnections between cerebellar, basal ganglia, and cerebral regions which are believed to work together during the sequence learning process. Together, this will provide a comprehensive framework of the neural organization of sequential learning and clarify the potential sequence-specific role of the cerebellum.