The teamwork behind the motor activity We are endowed with a rich palette of motor programs that rely on our ability to timely coordinate the recruitment of different muscle groups. This gift runs the whole gamut, from the large muscles used in rowing up to the smaller inner larynx muscles that control the closure of vocal cords. As we all quickly learned through jogging, movement means work, and work means energy. Just imagine the sheer metabolic rate of wings’ muscles in flying insects, when they beat their wings at 500 Hz! Although orchestrating such a complex pattern of muscle activation is a daunting task, a few organizational principles have emerged during evolution to cope with these demands. Firstly, as in sensory systems, there is a hierarchical control of muscle output, with increasingly more complex tasks being performed by groups of neurons that are higher up...