Introduction
CORTEX
The human brain is capable of learning numerous new motor tasks through practice. A crucial role in the learning process of motor tasks is attributed to the plasticity of the primary motor cortex (M1)One safe, non-invasive technique to investigate the impact of M1 in learning processes more directly is to impair the consolidation with the application of repetitive TMS (rTMS). Low-frequency rTMS over M1 is usually assumed to cause an inhibitory effect on motor cortical excitability and thus, interferes with cortical processesFor the current study, we hypothesized that if M1 is (at least partly) responsible for the adaptations in balance control, application of rTMS should impair consolidation of balance tasks. In contrast, if the reported changes in M1 (e.g. reduced excitability of M1 or enhanced SICI) are only the consequence of improved balance control (e.g. less postural sway) but are not the driving force, disruption of M1 should not impair consolidation of balance tasks. For this purpose, two groups were tested, one receiving rTMS and the other sham rTMS over M1 after having performed a balance learning task. The results showed an improved balance performance in the retention test in participants who received sham-rTMS and decreased performance in participants with the application of rTMS. Thus, our study proposes the direct involvement of M1 in the early phase of learning and consolidating a balance task.