About this Research Topic
During the second half of the last century an enormous amount of knowledge about mammalian motoneuron pools has been collected. This progress was enabled mostly by the development of the precise techniques of intracellular recordings in acute animal experiments, many of which were conducted under deep anaesthesia. Recently obtained evidence indicates that anaesthetics used at that times changed certain properties of the cell membrane, which might affect firing of the neuron. Experiments on normal humans gets around this problem, which lets one compare MN firing characteristics in humans and reduced preparations.
Firing pattern of human motoneurons is obtained indirectly by recording from a few muscle fibres of a motor unit. Since there is one-to-one relationship between motor unit and motoneuron firing, the analysis of motor unit firing is equivalent to the analysis of motoneuron firing. This analysis, based on the essential knowledge about motoneuron physiology, gained from the direct measurements in animal experiments and verified by computer simulations, allows one to draw conclusions about the physiological properties of human motoneurons. For obvious reasons, human motoneuron studies rely on indirect measurement methods, so the analysis and interpretation of their results should be performed with caution. On the other hand, human experiments provide the unique opportunity to study intact motoneurons during normal physiological behavior. Thus, combining information obtained from animal and human experiments, and computer simulations, gives insight to so far underexplored problems of motor control.
Despite the years of extensive research, there are still many unsolved problems in human motoneuron research. One of the less explored area is the question of interaction of motoneuron with supraspinal commands and neighboring interneurons, such as Renshaw cells or Ib inhibitory interneurons; their role in shaping motor control commands is still unclear. The role of persistent inward currents in normal motoneuron activity and the changes of motoneuron properties in neuromuscular system dysfunctions are far from being fully understood. We welcome contributions dealing with these and other questions, both experimental and from computer modeling. Reviews and opinions are also very important and would be highly appreciated.
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