By simultaneously recording multi-neuronal activities through chronically implanted electrode arrays in motor and sensory cortices, arm movement trajectory, and muscle activities, we observed both spatial and temporal differences in neuronal activities during different phases of a reaching task. We also discovered that when developing an effective control strategy to overcome an externally applied perturbation, the direction of the movement and the arm configuration played an important role in determining which control strategy to apply. The results indicated that predictive trajectory compensation was often adopted while stiffness control was also utilized.