proprio ceptive system reflex aspect de sherrington sir charles scott (1 resultados)

Brain, 29/96. - "The Hughlings Jackson Number. - London, Macmillan & Co., Ltd., 1906, 8°, pp.467-482, orig. wrappers. Rare Offprint! Sir Charles Scott Sherrington (1857-1952) "investigated and explained the proprioceptive system." "Sherrington defined proprioceptors as deep receptors for stimuli that 'are traceable to actions of the organism itself and . . . since . . . the stimuli to the receptors are delivered by the organism itself the deep receptors may be termed proprioceptors, and the deep field a field of proprioception'. The latin word proprius. meaning own, provided a prefix which called attention to the fact that the organism's own acts created the adequate stimuli for these deep receptors. Having defined proprioception, Sherrington went on to point out a property of proprioceptive reflexes which is sometimes forgotten: the amount of muscle activity mobilized by proprioceptive inputs is relatively slight. Careful attention to Sherrington's statements that (1) adequate stimuli for proprioceptors arise from the actions of the organism itself and that (2) proprioceptive effects on muscle discharge are 'mild', will be most useful as we seek to interpret data on reflex responses to muscle and joint afferent inputs. First, such careful attention will prevent us from forgetting that passive movements (i.e. those resulting from events arising within the environment) do not affect proprioceptors in the same way as active movements by the organism itself. Unfortunately, the essential role of the organism's own active movements in generating adequate stimuli for proprioceptors puts neurophysiologists in a quandry: systematic laboratory investigation of proprioceptive systems requires the use of externally produced changes of muscle length or tension, but these same externally produced changes (though they have marked effects on impulse frequencies of proprioceptive afferent fibers) do not provide proprioceptors with adequate stimuli. Perhaps the solution to this quandry lies in interpreting the consequences of external stimulation of proprioceptors with the same caution that we exercise in interpreting the consequences of electrical stimulation of the nervous system. Certainly, most of what we know about proprioceptive systems has been gained by observing the reflex consequences of externally produced changes of muscle length and tension, and the use of these inadequate stimuli does not really lead us astray until we place excessive reliance on these consequences in seeking to arrive at formulations as to the functional significance of proprioceptive reflexes." Evarts, E.V., Sherrington's concept of proprioception. Trends Neurosci. 4 (1981), pp.44-46. Garrison & Morton No. 1300.1.