Many studies suggest that the cerebellum is important for motor control, particularly motor execution and learning. However, it remains unknown how the cerebellum controls motor inhibition. The deep cerebellar nuclei (DCN) are parts of the main output areas in the cerebellum and have disynaptic connection with the basal-ganglia circuit, which is thought to be a key circuit for motor inhibition, via the centrolateral thalamic nuclei (CL). So, it is highly possible that the DCN-CL neurons have some roles in motor inhibition. In order to validate this possibility, I plan to conduct calcium imaging with fiber photometry from mice performing a novel stop-signal task (SST). First, I will inject AAV expressing calcium indicators into the DCN and implant an optical fiber in the CL in order to measure activity specific to the DCN-CL neurons. Subsequently, I will make the mice perform the SST. In the task the mice exhibit two types of motor inhibition, namely reactive and proactive inhibition. I can analyze activity in the DCN-CL neurons under various types of motor inhibition through the experiments. I expect that this research would provide insight into neural mechanisms for motor inhibition and could help to understand disorders with deficits of motor inhibition control (e.g. Parkinsonism).