Chapter 39 Properties of Human Peripheral Nerves: Implications for Studies of Human Motor Control

Abstract

Publisher Summary In neurophysiological studies on human subjects, considerable reliance is placed on the data previously obtained from the studies of animals. This translation has been extremely fruitful for the groups of neurophysiologists working on, for example, developing methods to record and stimulate single human axons (microneurography) and to stimulate the cortex, noninvasively (transcranial electrical and magnetic stimulation). However, in many cases those studying human subjects have assumed that what is known from animal studies can be applied without reservation to the more problematic world of human physiology and, more importantly, pathophysiology. This chapter discusses some issues involving peripheral nerve functions and draws implications for the studies of motor control in human subjects. Neural volleys have been found to disperse by the time they reach the motoneuron pool, whether they come from supraspinal centers or from peripheral sources. This is rarely recognized when central conduction times are calculated. The degree of dispersion of the volley depends on many factors, such as the nature of the stimulus, the duration of the stimulus, the spread of conduction velocities for the afferent volley, the length of the pathway to the target motoneurons, the existence of interneurons in the pathway, and the excitability of the responding neurons.