Recruitment of alpha and gamma-motoneurons in rats, dogs and humans.
1. Single fibre action potentials were recorded with 2 pairs of wire electrodes from human and dog lower sacral nerve roots and the rat nervus suralis. From the widths of single peaks of alpha 1 (FF), alpha 2 (FR), alpha 3 (S) (extrafusal) and gamma 1 and gamma 21-motoneurons (intrafusal) conduction velocity frequency distribution histograms were constructed and the limits of the velocity ranges determined. Distribution changes of conduction velocities in each group of alpha and gamma-motoneurons were used for recruitment analysis in the occasional firing mode. 2. In the dog, the rat and the human, the slower conducting fibres were recruited before the faster conducting ones in each group of motoneurons. In the dog, the slowly conducting gamma 1 and alpha 2-motoneurons were recruited directly following bladder catheter pulling, and the slowly conducting alpha 3-motoneurons were recruited 1 sec later. In the rat, the slowly conducting alpha 1-motoneurons were recruited directly following pin-pricking of the hindlimb, the slowly conducting alpha 2-motoneurons 0.2 sec later, and the slowly conducting alpha 3-motoneurons 1 sec later. In humans, the slowly conducting gamma 1 and alpha 2-motoneurons were recruited 2 sec following bladder catheter pulling, the slowly conducting alpha 3-motoneurons 4 sec following pulling. 3. In the dog, with no additional stimulation slowly (and fast) conducting gamma 21 and alpha 3-motoneurons showed repeated activation 3 to 4 sec later. A subgroup of the alpha 1-motoneurons showed repeated activation every 2 sec. In the rat, without stimulation, a slower conducting subgroup of the alpha 1-motoneurons showed preferential activation of the low and high conduction velocities every 2 sec. In the human, with no additional stimulation, the slowly and fast conducting alpha 2 and alpha 3-motoneurons were recruited repeatedly every 2 sec.
Schalow
G
G
Institute of Pathology, University of Greifswald, Germany.
Wattig
B
B
D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D001369:Axons / Q000502:physiology / Q000648:ultrastructure; D004285:Dogs; D004558:Electric Stimulation; D006801:Humans; D009046:Motor Neurons / Q000166:cytology / Q000502:physiology*; D009047:Motor Neurons, Gamma / Q000502:physiology*; D009186:Myelin Sheath / Q000648:ultrastructure; D009412:Nerve Fibers / Q000502:physiology / Q000648:ultrastructure; D009413:Nerve Fibers, Myelinated / Q000648:ultrastructure; D009431:Neural Conduction / Q000502:physiology; D009475:Neurons, Afferent / Q000502:physiology / Q000648:ultrastructure; D009476:Neurons, Efferent / Q000502:physiology / Q000648:ultrastructure; D010141:Pacinian Corpuscles / Q000502:physiology / Q000648:ultrastructure; D010275:Parasympathetic Nervous System / Q000166:cytology / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D011999:Recruitment, Neurophysiological / Q000502:physiology*; D012867:Skin / Q000294:innervation; D013126:Spinal Nerve Roots / Q000033:anatomy & histology / Q000502:physiology; D013497:Sural Nerve / Q000033:anatomy & histology / Q000502:physiology