Motoneurone task groups: coping with kinematic heterogeneity

Journal of Experimental Biology - Tập 115 Số 1 - Trang 137-146 - 1985
G. E. Loeb1
1IRP National Institute of Neurological and Communicative Disorders and Stroke Laboratory of Neural Control , , Bethesda, MD 20205, U.S.A

Tóm tắt

ABSTRACT Physiological principles of motor control have generally been based on linear servocontrol theories in which transducers of force, length and velocity are used to provide feedback to the motor actuators. Within the past few years, recordings of the activity of motoneurones and proprioceptors during normal motor behaviour have indicated a diversity that is not consistent with any one theory of motor control. This paper examines the heterogeneity of kinematic conditions under which muscles are called on to perform, and attempts to correlate this with the effects of various fusimotor states on the activity of the muscle spindle afferents, the major sensory signal source in most feedback control schemes. The concept of ‘task groups’ is proposed, in which functional groups of alpha and gamma motoneurones and spindle afferents are programmed to achieve optimal control over relatively restricted but more linear parts of their operating curves. Such a functional compartmentalization of the motor apparatus is thus consistent with several different theories of servocontrol, although it remains unclear whether such conceptual mechanisms are actually embodied in the highly complex neural circuitry present in the spinal cord and higher motor centres.

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Tài liệu tham khảo

Bizzj, 1982, Arm trajectory formation in monkeys, Expl Brain Res., 46, 139, 10.1007/BF00238107

Boyd, 1981, The action of the three types of intrafusal fibre in isolated cat muscle spindles on the dynamic and length sensitivities of primary and secondary sensory endings, In Muscle Receptors and Movement, 17, 10.1007/978-1-349-06022-1_3

Cavagna, 1974, Effect of stretching on the elastic characteristics and the contractile component of frog striated muscle, J. Physiol., Lond, 239, 1, 10.1113/jphysiol.1974.sp010552

Gans, 1982, Fiber architecture and muscle function, Exerc. Sports Sci. Rev, 11, 160

Granit, 1975, The functional role of the muscle spindles - facts and hypotheses, Brain, 98, 531, 10.1093/brain/98.4.531

Hasan, 1975, Transition in sensitivity of spindle receptors that occurs when muscle is stretched more than a fraction of a millimeter, J. Physiol., Lond, 38, 673

Henneman, 1974, Rank order of motoneurons within a pool: law of combination, J. Neurophysiol, 37, 1338, 10.1152/jn.1974.37.6.1338

Hill, 1938, The heat of shortening and the dynamic constants of muscle, Proc. R. Soc. B, 126, 136

Hoffer, 1980, Implantable electrical and mechanical interfaces with nerve and muscle, Ann. biomed. Eng, 8, 351, 10.1007/BF02363438

Hoffer, 1983, A technique for reversible fusimotor blockade during chrome recording from spindle afferents in walking cats, Expl Brain Res, 7, 272

Hoffer, 1980, Unitary activity patterns during walking confirm the existence of two functionally distinct classes of Sartorius motoneurones in cats, J. Physiol., Lond, 308, 20

Hoffer, 1981, Discharge patterns in hindlimb motoneurons during normal cat locomotion, Science, N.Y, 213, 466, 10.1126/science.7244644

Houk, 1979, Regulation of stiffness by skeletomotor reflexesA, Rev. Physiol, 41, 99, 10.1146/annurev.ph.41.030179.000531

Houk, 1981, Nature of the dynamic response and its relation to the high sensitivity of muscle spindles to small changes in length, In Muscle Receptors and Movement, 33, 10.1007/978-1-349-06022-1_4

Huluger, 1983, A new simulation method to deduce fusimotor activity from afferent discharge recorded in freely moving cats, J. Neurosci. Meth, 8, 197, 10.1016/0165-0270(83)90121-8

Jankowska, 1983, Intemeuronal organization in reflex pathways from proprioceptors, Proc. IUPS, 159

Joyce, 1969, The mechanical properties of cat soleus muscle during controlled lengthening and shortening movements, J. Physiol., Lond, 204, 461, 10.1113/jphysiol.1969.sp008924

Loeb, 1984, The control and response of muscle spindles during normally executed motor tasks, Exer. Sports Sa. Rev, 12, 157

Loeb, 1977, Long-term unit recording from somatosensory neurons in the spindle ganglia of the freely walking cat, Science, N.Y, 197, 1192, 10.1126/science.897663

Loeb, 1979, Activity patterns in individual hindlimb primary and secondary muscle spindle afferents during normal movements in unrestrained cats, J. Neurophysiol, 42, 420, 10.1152/jn.1979.42.2.420

Loeb, 1983, Reflex recruitment of individual cat hindlimb motoneurons by cutaneous shocks during normal walking, In Reflex Organization of the Spinal Cord and its Descending Control

Milner-Brown, 1973, The orderly recruitment of human motor units during voluntary isometric contractions, J. Physiol., Lond, 230, 359, 10.1113/jphysiol.1973.sp010192

Perret, 1975, A new classification of flexor and extensor muscles revealed by study of the central locomotor program in the deafferented cat, Expl Brain Res, 23, 160

Prochazka, 1976, Discharge of single hindlimb afferents in the freely moving cat, J. Neurophysiol, 39, 1090, 10.1152/jn.1976.39.5.1090

Rack, 1969, The effects of length and stimulus rate on tension in the isometric cat soleus muscle, J. Physiol., Lond, 204, 443, 10.1113/jphysiol.1969.sp008923

Stein, 1974, The peripheral control of movement, Physiol. Rev, 54, 215, 10.1152/physrev.1974.54.1.215

Walmsley, 1978, Forces produced by medial gastrocnemius and soleus muscles during locomotion in freely moving cats, J. Neurophysiol, 41, 1203, 10.1152/jn.1978.41.5.1203