Recruitment within the groups of gamma 1, alpha 2 and alpha 3-motoneurons in dogs and humans following bladder and anal catheter pulling.
Conduction velocity frequency distribution histograms were constructed from lower sacral root recordings of single intrafusal (gamma) and extrafusal (alpha) motoneurons. The velocity distributions of occasional and stimulated activity before and following bladder and anal catheter pulling were almost identical for dogs and humans. The limits of the velocity ranges of alpha 1(FF), alpha 2(FS) and alpha 3(S) and gamma beta(?)-motoneurons were determined from the broadness of the single peaks. The borders of the partly fused peaks of gamma 1 and gamma 21-motoneurons were estimated from their different functional properties. Activity levels of the alpha 1, alpha 2, alpha 3, gamma beta, gamma 1 and gamma 21-motoneurons were too complex to allow safe conclusions from the dog measurements, probably because of the representation of leg and tail in addition to sphincter functions in the lower sacral root. In the human dorsal S4 root, in which mainly efferent functions of sphincters only were contained, the gamma 21, gamma 1, alpha 2 and alpha 3-motoneurons showed simple behaviour. Distribution changes of conduction velocities in each group of alpha and gamma-motoneurons were used for recruitment analysis. Following stimulation in dogs and humans, within the groups of gamma 1, alpha 3 and alpha 2-motoneurons, slowly conducting fibres were activated before the faster conducting ones. The alpha 3-motoneurons were recruited later than the alpha 2-motoneurons. In the dog, low gamma 1 and alpha 2-motoneuron velocities occurred preferentially 0 to 0.2 s following strong bladder catheter pulling, probably in the mono- and oligosynaptic pathways. Low conduction velocities of alpha 3-motoneurons occurred more often 1 to 1.2 s following stimulation. At 2 to 2.2 s following stimulation, the high gamma 1 and alpha 2-motoneuron velocities were more activated. At 4 to 4.2 s following stimulation, low gamma 1 and alpha 2-motoneuron velocities were recruited again. Following strong bladder catheter pulling, co-recruitment of the gamma 1 and alpha 2-motoneurons seemed to occur. Following anal catheter pulling in the dog there was no co-recruitment of gamma 1 and alpha 2-motoneurons. In the case of gamma 1-alpha 2 co-recruitment, the gamma 1-motoneurons were recruited additionally once in between the co-recruitment. The higher frequency of recruitment of the gamma 1-motoneurons, and the separate recruitment of the gamma 1 and alpha 2-systems, indicate that the activation of gamma 1 and alpha 2-motoneurons are not strongly linked.(ABSTRACT TRUNCATED AT 400 WORDS)
Schalow
G
G
Department of Neuropathology, Freie Universität Berlin, Germany.
D001003:Anal Canal / Q000294:innervation; D000818:Animals; D055592:Biophysical Phenomena; D001703:Biophysics; D002404:Catheterization; D004285:Dogs; D004525:Efferent Pathways / Q000502:physiology; D004558:Electric Stimulation; D004594:Electrophysiology; D006801:Humans; D009046:Motor Neurons / Q000502:physiology*; D009431:Neural Conduction / Q000502:physiology; D009473:Neuronal Plasticity / Q000502:physiology; D010812:Physical Stimulation; D011999:Recruitment, Neurophysiological / Q000502:physiology*; D013045:Species Specificity; D001743:Urinary Bladder / Q000294:innervation