Gap in the literature in neuromuscular physiology: Since it is difficult to study the functions of the neuromuscular system in human subjects, most of our knowledge comes from studies on experimental animals. However, since the animals are usually anaesthetized or decerebrated in these experiments, and since such reduction processes are known to alter the synaptic interactions, it is not possible to directly apply these findings to human subjects. Therefore, details of the synaptic interactions between sensory or cortical afferents and motoneurons, the process of feed-back from the peripheral receptors to the motoneurons, the pathways used in these processes, and conditions where such synaptic interactions are modulated are still unknown in human subjects.