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Proprioceptive Feedback and Movement Regulation

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Abstract

The sections in this article are:

1 Sensory Feedback: Historical Background
1.1 Reflected Action: The “Sentient Principle”
1.2 Motor Effects of Sensory Loss
1.3 Central Pattern Generators and Sensory Feedback
2 Structure and Response Properties of Proprioceptors
2.1 Muscle Spindles
2.2 Tendon Organs
2.3 Spindle and Tendon Organ Densities: A Clue as to Function?
2.4 Proprioceptors in Joints, Ligaments, and Skin
2.5 Invertebrate Proprioceptors
3 Response Properties of Proprioceptors During Active Movement
3.1 Methodology
3.2 Muscle Spindles
3.3 Tendon Organs
3.4 Skin and Joint Afferents
3.5 Invertebrate Proprioceptors
4 Feedback Control
4.1 Basic Concepts, Definitions, and Types of Control System
4.2 Proprioceptive Control
5 Conclusion
Figure 1. Figure 1.

Effect of selective deafferentation on hand control in a macaque monkey. Finger movements in a key‐pressing task, before (top) and after (bottom) a cuneate fasciculus lesion. The premovement start position was similar in normal and lesioned animals (A and E), as was the final position (D and H). However, the individual control of fingers was dramatically lost after the lesion (compare F to B). The fingers extended, bore down on the key in unison (G) and finished in a tightly flexed power grip (H). From here a return to position F, with the fingers fully extended, was not uncommon, with multiple cycles of F‐G‐H in rapid succession.

Reproduced from Cooper et al.
Figure 2. Figure 2.

Electromyogram recordings from four hindlimb muscles in a decerebrate cat induced to walk on a treadmill by electrical stimulation of the midbrain locomotor area. The relative timing of the bursts of activity is remarkably similar before (A) and after (B) bilateral hindlimb deafferentation. ext., extensor; quadr., quadriceps; gastroc, gastrocnemius; EDB, extensor digitorum brevis; Ip, iliopsoas.

Adapted from Grillner and Zangger
Figure 3. Figure 3.

Schematic of a mammalian muscle spindle (A) and Golgi tendon organ (B). The γ‐ and β‐fusimotor axons innervate six to ten intrafusal muscle fibers (not all shown). The β‐motoneurons also innervate extrafusal muscle fibers as indicated. The central regions of the intrafusal fibers, around which the group Ia and II sensory afferents spiral, are noncontractile. When the polar ends of the intrafusal fibers contract in response to γ and/or β activity, the sensory regions are stretched, causing increased Ia and II firing. Dynamic fusimotor action stiffens the bag, intrafusal muscle fiber, so that when the ends of the spindle are stretched, more of the stretch is imparted to the sensory region, thus sensitizing the Ia ending. The terminal branches of the tendon organ are entwined amongst the musculotendinous strands of 10–20 motor units, and “sample” the active force produced by them.

Adapted from Kandel et al. and Zelena and Soukup
Figure 4. Figure 4.

Schematic summary of the firing rate responses of group Ia and II spindle afferents to trapezoidal length changes with and without concomitant fusimotor stimulation. The firing rates shown are typical of displacements of about 10% of rest‐length and velocities of 0.05 rest‐length/s. The horizontal bars indicate periods of fusimotor stimulation at 100/s. Note the big increase in Ia stretch sensitivity with γd stimulation and the strong biasing effect of γs stimulation. Combined γd and γs stimulation gives occlusion effects. ips, imp/s.

Adapted from Prochazka
Figure 5. Figure 5.

Techniques to record from single nerve fibers in conscious humans (A), monkeys (B), and cats (C and D). A, Schematic profile of a neurography electrode pushed amongst Ia axons in a peripheral nerve (shown in cross section). The uninsulated portion of tip is about 30 μm long. Single‐unit selectivity probably relies on proximity of tip to a node of Ranvier of an axon.

Adapted from Wall and McMahon .] B, Exploded view of recording chamber over monkey cervical (C7, C8) dorsal root ganglia (DRG). Holes drilled through the lateral vertebral processes allow access to DRG by microelectrodes lowered in chamber. [Adapted from Schieber et al. .] C, Loeb's “hatpin” microwire implants in cat lumbar (L5) dorsal root ganglion (DRG). Microwire lead from DRG is stabilized on a Silastic sheet sutured between L5 and L6 vertebral spinous processes, then tunneled up to connector back‐pack. D, Floating microwire variant of C, showing stabilization of cable shield in dental acrylic cap on L7 spinous process. Microwires are also stuck and/or sutured to dura mater. C and D adapted from Prochazka
Figure 6. Figure 6.

Activity of group I and II afferent fibers and α and γ motor fibers during spontaneous air‐stepping movements in high decerebrate cats. The mean firing rate profiles were estimated by electronically sorting afferent and efferent signals in a branch of the nerve to lateral gastrocnemius muscle. The technique does not differentiate between spindle Ia and tendon organ Ib afferent activity, but in this experiment Ia activity probably dominated the group I record, because there was no ground contact or weight bearing. Muscle lengthening is shown by the arrow. Both Ia and II afferents fired mainly during muscle stretch. The γ activity was modulated in time with the α bursts and whole‐muscle electromyogram and there was an additional tonic offset or bias (i.e., there were both phasic and tonic components of γ discharge).

Adapted from Bessou et al.
Figure 7. Figure 7.

Firing rate profiles of a monkey wrist‐flexor spindle afferent recorded during voluntary wrist movements tracking a displayed ramp‐and‐hold target. Each profile is an average of several trials. Actual wrist movement was not shown, but it is assumed that tracking was good. Six combinations of movement and loading condition are shown. Left column, wrist extension trials (muscle lengthens); right column, wrist flexion (muscle shortens). Top row, no load; middle row, steady extensor load; bottom, flexor load. During muscle lengthening, afferent increases its firing rate. At onset of shortening, smaller increases in rate are seen, indicating some γ action. Relationship to loading conditions was interpreted as evidence for independence of γ and α activity.

Adapted from Schieber and Thach
Figure 8. Figure 8.

Mean firing rate profiles of the three types of large‐diameter afferents in cat triceps surae muscles in the step cycle. The ensemble data were averaged from chronic recordings of nine Ia afferents, two II afferents, and four Ib afferents. Each afferent contributed four step cycles. The firing rate profiles are event histograms of 10 ms bin width calibrated in terms of mean firing rate. The electromyogram and length averages were obtained from the Ia data only, but were similar for the II and Ib recordings. Note the high peak firing rate of tendon organ Ib afferents during the stance phase.

Adapted from Prochazka et al.
Figure 9. Figure 9.

Same Ia data as in Figure , but this time aligned to the moment of foot contact, thus exaggerating the contact‐related Ia firing transient. Dashed curve was obtained by digitally filtering the length profile using equation . Bottom trace shows difference between ensemble profile and model (i.e., the firing rate not accounted for). The modulation depth of the ensemble profile is 108 imp/s; that of the error signal is 67 imp/s. The error reflects factors such as fusimotor modulation, tendon compliance effects, and muscle unloading. There is no clear relation ship between the error and the electromyogram, indicating that α‐linked components of γ action were not dominant.

Figure 10. Figure 10.

Activity of a human spindle primary (group Ia) and secondary (group II) afferent of a finger extensor in imposed movements and voluntary isometric contractions. A, Both afferents responded to muscle stretch. As the muscle shortened, the group Ia afferent fell silent and the group II afferent reduced its firing rate. B, Both endings showed increased firing during isometric contractions of the receptor‐bearing muscle, monitored as torque about the metacarpophalangeal (MCP) joint.

Adapted from Edin and Vallbo
Figure 11. Figure 11.

Response of a human muscle spindle afferent of a finger extensor to imposed movements and voluntary movements against a small external load opposing finger extension. A, The afferent responded to the imposed sinusoidal displacement and maintained its firing during muscle shortening, indicating some fusimotor action. There was minimal electromyographic activity during the imposed movements. B, The spindle responded to the active movements in much the same way. There was no evidence in this case of additional firing linked to the voluntary electromyogram, as would be expected from α–γ co‐activation.

Adapted from Al‐Falahe et al. (
Figure 12. Figure 12.

Ankle extensor Ia firing illustrating a sudden change in stretch‐sensitivity when the hindlimb of a cat walking along a table surface slipped on the edge of the table. The record is continuous from upper to lower panel. At the moment marked with the arrow, the cat slipped and crouched, the receptor‐bearing muscle actively lengthened, and the spindle afferent responded with firing rates of nearly 400 imp/s. This was interpreted as a sudden task‐ or context‐related increase in γd action, exemplifying “fusimotor set.”

Adapted from Prochazka et al.
Figure 13. Figure 13.

Firing of single Golgi tendon organ afferents during slowly increasing muscle force in (A) a human finger extensor muscle and (B) an ankle extensor muscle in the awake cat. The arrows indicate increments in firing rate attributed to progressive recruitment of motor units. The rate increments and overall range of firing rate of the human tendon organ were smaller than in the cat: finger extensor force was expressed as a percentage of maximal voluntary contraction (% MVC). For comparison, in the cat 10 N measured at the footpads is roughly equivalent to 15% maximal force .

A Adapted from Edin and Vallbo , B from Appenteng and Prochazka
Figure 14. Figure 14.

SAII skin receptor responses to stretching the skin in the receptive field at the angles shown (0 degrees is along forearm axis). Each plot shows the firing rate responses to five skin stretches applied along the angular axis indicated and causing strains of 1.25%, 2.5%, 5%, 10%, and 20%, respectively. The sensitivity along a given axis was expressed as the adapted response per % strain (i.e., imp · s−1 · %strain−1), and superimposed on the diagram of the hand as a vector with appropriate length and orientation. This receptor would presumably respond best to flexion of the forefinger, but it might also respond to flexion of the other fingers and the thumb.

Adapted from Edin
Figure 15. Figure 15.

Schematic illustrating the equilibrium point hypothesis. When the book is removed, the arm flexes to a new stable position, close to the threshold of the stretch reflex (the virtual position λ).

Adapted from McCloskey and Prochazka
Figure 16. Figure 16.

Schematics of stick insect, locust, lobster, cat, active leg prosthesis, and man using functional electrical stimulation. In each case, pairs of sensory variables are indicated that have been shown to be used in a conditional way to initiate the swing phase of gait (i.e., IF displacement exceeds threshold AND force has declined below threshold, THEN initiate flexion). Approximate positions of identified sensors (natural and artificial) are shown.

Adapted from Prochazka


Figure 1.

Effect of selective deafferentation on hand control in a macaque monkey. Finger movements in a key‐pressing task, before (top) and after (bottom) a cuneate fasciculus lesion. The premovement start position was similar in normal and lesioned animals (A and E), as was the final position (D and H). However, the individual control of fingers was dramatically lost after the lesion (compare F to B). The fingers extended, bore down on the key in unison (G) and finished in a tightly flexed power grip (H). From here a return to position F, with the fingers fully extended, was not uncommon, with multiple cycles of F‐G‐H in rapid succession.

Reproduced from Cooper et al.


Figure 2.

Electromyogram recordings from four hindlimb muscles in a decerebrate cat induced to walk on a treadmill by electrical stimulation of the midbrain locomotor area. The relative timing of the bursts of activity is remarkably similar before (A) and after (B) bilateral hindlimb deafferentation. ext., extensor; quadr., quadriceps; gastroc, gastrocnemius; EDB, extensor digitorum brevis; Ip, iliopsoas.

Adapted from Grillner and Zangger


Figure 3.

Schematic of a mammalian muscle spindle (A) and Golgi tendon organ (B). The γ‐ and β‐fusimotor axons innervate six to ten intrafusal muscle fibers (not all shown). The β‐motoneurons also innervate extrafusal muscle fibers as indicated. The central regions of the intrafusal fibers, around which the group Ia and II sensory afferents spiral, are noncontractile. When the polar ends of the intrafusal fibers contract in response to γ and/or β activity, the sensory regions are stretched, causing increased Ia and II firing. Dynamic fusimotor action stiffens the bag, intrafusal muscle fiber, so that when the ends of the spindle are stretched, more of the stretch is imparted to the sensory region, thus sensitizing the Ia ending. The terminal branches of the tendon organ are entwined amongst the musculotendinous strands of 10–20 motor units, and “sample” the active force produced by them.

Adapted from Kandel et al. and Zelena and Soukup


Figure 4.

Schematic summary of the firing rate responses of group Ia and II spindle afferents to trapezoidal length changes with and without concomitant fusimotor stimulation. The firing rates shown are typical of displacements of about 10% of rest‐length and velocities of 0.05 rest‐length/s. The horizontal bars indicate periods of fusimotor stimulation at 100/s. Note the big increase in Ia stretch sensitivity with γd stimulation and the strong biasing effect of γs stimulation. Combined γd and γs stimulation gives occlusion effects. ips, imp/s.

Adapted from Prochazka


Figure 5.

Techniques to record from single nerve fibers in conscious humans (A), monkeys (B), and cats (C and D). A, Schematic profile of a neurography electrode pushed amongst Ia axons in a peripheral nerve (shown in cross section). The uninsulated portion of tip is about 30 μm long. Single‐unit selectivity probably relies on proximity of tip to a node of Ranvier of an axon.

Adapted from Wall and McMahon .] B, Exploded view of recording chamber over monkey cervical (C7, C8) dorsal root ganglia (DRG). Holes drilled through the lateral vertebral processes allow access to DRG by microelectrodes lowered in chamber. [Adapted from Schieber et al. .] C, Loeb's “hatpin” microwire implants in cat lumbar (L5) dorsal root ganglion (DRG). Microwire lead from DRG is stabilized on a Silastic sheet sutured between L5 and L6 vertebral spinous processes, then tunneled up to connector back‐pack. D, Floating microwire variant of C, showing stabilization of cable shield in dental acrylic cap on L7 spinous process. Microwires are also stuck and/or sutured to dura mater. C and D adapted from Prochazka


Figure 6.

Activity of group I and II afferent fibers and α and γ motor fibers during spontaneous air‐stepping movements in high decerebrate cats. The mean firing rate profiles were estimated by electronically sorting afferent and efferent signals in a branch of the nerve to lateral gastrocnemius muscle. The technique does not differentiate between spindle Ia and tendon organ Ib afferent activity, but in this experiment Ia activity probably dominated the group I record, because there was no ground contact or weight bearing. Muscle lengthening is shown by the arrow. Both Ia and II afferents fired mainly during muscle stretch. The γ activity was modulated in time with the α bursts and whole‐muscle electromyogram and there was an additional tonic offset or bias (i.e., there were both phasic and tonic components of γ discharge).

Adapted from Bessou et al.


Figure 7.

Firing rate profiles of a monkey wrist‐flexor spindle afferent recorded during voluntary wrist movements tracking a displayed ramp‐and‐hold target. Each profile is an average of several trials. Actual wrist movement was not shown, but it is assumed that tracking was good. Six combinations of movement and loading condition are shown. Left column, wrist extension trials (muscle lengthens); right column, wrist flexion (muscle shortens). Top row, no load; middle row, steady extensor load; bottom, flexor load. During muscle lengthening, afferent increases its firing rate. At onset of shortening, smaller increases in rate are seen, indicating some γ action. Relationship to loading conditions was interpreted as evidence for independence of γ and α activity.

Adapted from Schieber and Thach


Figure 8.

Mean firing rate profiles of the three types of large‐diameter afferents in cat triceps surae muscles in the step cycle. The ensemble data were averaged from chronic recordings of nine Ia afferents, two II afferents, and four Ib afferents. Each afferent contributed four step cycles. The firing rate profiles are event histograms of 10 ms bin width calibrated in terms of mean firing rate. The electromyogram and length averages were obtained from the Ia data only, but were similar for the II and Ib recordings. Note the high peak firing rate of tendon organ Ib afferents during the stance phase.

Adapted from Prochazka et al.


Figure 9.

Same Ia data as in Figure , but this time aligned to the moment of foot contact, thus exaggerating the contact‐related Ia firing transient. Dashed curve was obtained by digitally filtering the length profile using equation . Bottom trace shows difference between ensemble profile and model (i.e., the firing rate not accounted for). The modulation depth of the ensemble profile is 108 imp/s; that of the error signal is 67 imp/s. The error reflects factors such as fusimotor modulation, tendon compliance effects, and muscle unloading. There is no clear relation ship between the error and the electromyogram, indicating that α‐linked components of γ action were not dominant.



Figure 10.

Activity of a human spindle primary (group Ia) and secondary (group II) afferent of a finger extensor in imposed movements and voluntary isometric contractions. A, Both afferents responded to muscle stretch. As the muscle shortened, the group Ia afferent fell silent and the group II afferent reduced its firing rate. B, Both endings showed increased firing during isometric contractions of the receptor‐bearing muscle, monitored as torque about the metacarpophalangeal (MCP) joint.

Adapted from Edin and Vallbo


Figure 11.

Response of a human muscle spindle afferent of a finger extensor to imposed movements and voluntary movements against a small external load opposing finger extension. A, The afferent responded to the imposed sinusoidal displacement and maintained its firing during muscle shortening, indicating some fusimotor action. There was minimal electromyographic activity during the imposed movements. B, The spindle responded to the active movements in much the same way. There was no evidence in this case of additional firing linked to the voluntary electromyogram, as would be expected from α–γ co‐activation.

Adapted from Al‐Falahe et al. (


Figure 12.

Ankle extensor Ia firing illustrating a sudden change in stretch‐sensitivity when the hindlimb of a cat walking along a table surface slipped on the edge of the table. The record is continuous from upper to lower panel. At the moment marked with the arrow, the cat slipped and crouched, the receptor‐bearing muscle actively lengthened, and the spindle afferent responded with firing rates of nearly 400 imp/s. This was interpreted as a sudden task‐ or context‐related increase in γd action, exemplifying “fusimotor set.”

Adapted from Prochazka et al.


Figure 13.

Firing of single Golgi tendon organ afferents during slowly increasing muscle force in (A) a human finger extensor muscle and (B) an ankle extensor muscle in the awake cat. The arrows indicate increments in firing rate attributed to progressive recruitment of motor units. The rate increments and overall range of firing rate of the human tendon organ were smaller than in the cat: finger extensor force was expressed as a percentage of maximal voluntary contraction (% MVC). For comparison, in the cat 10 N measured at the footpads is roughly equivalent to 15% maximal force .

A Adapted from Edin and Vallbo , B from Appenteng and Prochazka


Figure 14.

SAII skin receptor responses to stretching the skin in the receptive field at the angles shown (0 degrees is along forearm axis). Each plot shows the firing rate responses to five skin stretches applied along the angular axis indicated and causing strains of 1.25%, 2.5%, 5%, 10%, and 20%, respectively. The sensitivity along a given axis was expressed as the adapted response per % strain (i.e., imp · s−1 · %strain−1), and superimposed on the diagram of the hand as a vector with appropriate length and orientation. This receptor would presumably respond best to flexion of the forefinger, but it might also respond to flexion of the other fingers and the thumb.

Adapted from Edin


Figure 15.

Schematic illustrating the equilibrium point hypothesis. When the book is removed, the arm flexes to a new stable position, close to the threshold of the stretch reflex (the virtual position λ).

Adapted from McCloskey and Prochazka


Figure 16.

Schematics of stick insect, locust, lobster, cat, active leg prosthesis, and man using functional electrical stimulation. In each case, pairs of sensory variables are indicated that have been shown to be used in a conditional way to initiate the swing phase of gait (i.e., IF displacement exceeds threshold AND force has declined below threshold, THEN initiate flexion). Approximate positions of identified sensors (natural and artificial) are shown.

Adapted from Prochazka
References
 1. Abrahams, V. C., and F. J. R. Richmond. Specialization of sensorimotor organization in the neck muscle system. Prog. Brain Res. 76: 125–135, 1988.
 2. Ageranioti‐Belanger, S. A., and C. E. Chapman. Discharge properties of neurones in the hand area of primary somatosensory cortex in monkeys in relation to the performance of an active tactile discrimination task. II. Area 2 as compared to areas 3b and 1. Exp. Brain Res. 91: 207–228, 1992.
 3. Al‐Falahe, N. A., M. Nagaoka, and A. B. Vallbo. Lack of fusimotor modulation in a motor adaptation task in man. Acta Physiol. Scand. 140: 23–30, 1990a.
 4. Al‐Falahe, N. A., M. Nagaoka, and A. B. Vallbo. Response profiles of human muscle afferents during active finger movements. Brain 113: 325–346, 1990b.
 5. Alnaes, E. Static and dynamic properties of Golgi tendon organs in the anterior tibial and soleus muscles of the cat. Acta Physiol. Scand. 70: 176–187, 1967.
 6. Alstermark, B., A. Lundberg, and L.‐G. Pettersson. The pathway from Ia forelimb afferents to motor cortex: a new hypothesis. Neurosci. Res. 11: 221–225, 1991.
 7. Amassian, V. E., R. Q. Cracco, and P. J. Maccabee. A sense of movement elicited in paralyzed distal arm by focal magnetic coil stimulation of human motor cortex. Brain Res. 479: 355–360, 1989.
 8. Anderson, J. H. Dynamic characteristics of Golgi tendon organs. Brain Res. 67: 531–537, 1974.
 9. Andersson, O., and S. Grillner. Peripheral control of the cat's step cycle. II. Entrainment of the central pattern generators for locomotion by sinusoidal hip movements during “fictive locomotion.” Acta Physiol. Scand. 118: 229–239, 1983.
 10. Aniss, A. M., H.‐C. Diener, J. Hore, S. C. Gandevia, and D. Burke. Behavior of human muscle receptors when reliant on proprioceptive feedback during standing. J. Neurophysiol. 64: 661–670, 1990.
 11. Appelberg, B. Central control of extensor muscle spindle dynamic sensitivity. Life Sci. 9: 706–708, 1963.
 12. Appelberg, B. Selective central control of dynamic gamma motoneurones utilised for the functional classification of gamma cells. In: Muscle Receptors and Movement, edited by A. Taylor and A. Prochazka. London: Macmillan, 1981, p. 97–108.
 13. Appenteng, K., J. P. Lund, and J. J. Seguin. Behavior of cutaneous mechanoreceptors recorded in mandibular division of gasserian ganglion of the rabbit during movements of lower jaw. J. Neurophysiol. 47: 151–166, 1982.
 14. Appenteng, K., T. Morimoto, and A. Taylor. Fusimotor activity in masseter nerve of the cat during reflex jaw movements. J. Physiol. (Lond.) 305: 415–432, 1980.
 15. Appenteng, K., and A. Prochazka. Tendon organ firing during active muscle lengthening in normal cats. J. Physiol. (Lond.) 353: 81–92, 1984.
 16. Avendano, C., A. J. Isla, and E. Rausell. Area 3a in the cat. II. Projections to the motor cortex and their relations to other corticocortical connections. J. Comp. Neurol. 321: 373–386, 1992.
 17. Awiszus, F., and S. S. Schafer. Subdivision of primary afferents from passive cat muscle spindles based on a single slow‐adaptation parameter. Brain Res. 612: 110–114, 1993.
 18. Baev, K. V., and Y. P. Shimansky. Principles of organization of neural systems controlling automatic movements in animals. Prog. Neurobiol. 39: 45–112, 1992.
 19. Baldissera, F., H. Hultborn, and M. Illert. Integration in spinal neuronal systems. In: Handbook of Physiology, The Nervous System, Motor Control, edited by V. B. Brooks. Bethesda, MD: Am. Physiol. Soc., 1982, p. 509–595.
 20. Banks, R. W., and M. J. Stacey. Quantitative studies on mammalian muscle spindles and their sensory innervation. In: Mechanoreceptors: Development, Structure and Function, edited by P. Hnik, T. Soukup, R. Vejsada, and J. Zelena. London: Plenum, 1988, p. 263–269.
 21. Barker, D. The morphology of muscle receptors. In: Handbook of Sensory Physiol. Vol. 3, Part 2 (Muscle Receptors), edited by C. C. Hunt. Berlin: Springer, 1974, p. 1–190.
 22. Barnes, W. J. P. Proprioceptive influences on motor output during walking in the crayfish. J. Physiol. (Paris) 73: 543–564, 1977.
 23. Bassler, U. Neural Basis of Elementary Behavior in Stick Insects. Studies of Brain Function. Berlin: Springer, 1983, p. 169.
 24. Bässler, U. The femur‐tibia control system of stick insects—a model system for the study of the neural basis of joint control. Brain Res. Rev. 18: 207–226, 1993.
 25. Bässler, U. The walking‐ (and searching‐) pattern generator of stick insects, a modular system composed of reflex chains and endogenous oscillators. Biol. Cybern. 69: 305–317, 1993.
 26. Bässler, U., and U. Nothof. Gain control in a proprioceptive feedback loop as a prerequisite for working close to instability. J. Comp. Physiol. [A] 175: 23–33, 1994.
 27. Baumann, T. K., and M. Hulliger. The dependence of the response of cat spindle Ia afferents to sinusoidal stretch on the velocity of concomitant movement. J. Physiol. (Lond.) 439: 325–350, 1991.
 28. Bennett, D. J., M. Gorassini, and A. Prochazka. Catching a ball: contributions of intrinsic muscle stiffness, reflexes and higher‐order responses. Can. J. Physiol. Pharmacol. 72: 525–534, 1994.
 29. Berger, W., V. Dietz, and J. Quintern. Corrective reactions to stumbling in man: neuronal coordination of bilateral leg muscle activity during gait. J. Physiol. (Lond.) 357: 109–125, 1984.
 30. Bergmans, J., and S. Grillner. Reciprocal control of spontaneous activity and reflex effects in static and dynamic flexor alpha‐motoneurones revealed by an injection of DOPA. Acta Physiol. Scand. 77: 106–124, 1969.
 31. Berkinblit, M. B., A. G. Feldman, and O. I. Fukson. Adaptability of innate motor patterns and motor control mechanisms. Behav. Brain Sci. 9: 585–638, 1986.
 32. Bernstein, N. A. Trends and problems in the study of investigation of physiology of activity. In: The Coordination and Regulation of Movements. Oxford: Pergamon, 1967 (Orig. Questions of Philosophy, Vopr. Filos. 6: 77–92, 1961).
 33. Bessou, P., J.‐M. Cabelguen, M. Joffroy, R. Montoya, and B. Pages. Efferent and afferent activity in a gastrocnemius nerve branch during locomotion in the thalamic cat. Exp. Brain Res. 64: 553–568, 1986.
 34. Bessou, P., M. Joffroy, R. Montoya, and B. Pages. Evidence of the co‐activation of Alpha‐motoneurones and static gamma‐motoneurones of the sartorius medialis muscle during locomotion in the thalamic cat. Exp. Brain Res. 82: 191–198, 1990.
 35. Binder, M. D. Further evidence that the Golgi tendon organ monitors the activity of a discrete set of motor units within a muscle. Exp. Brain Res. 43: 186–192, 1981.
 36. Binder, M. D., and D. G. Stuart. Responses of Ia and spindle group II afferents to single motor‐unit contractions. J. Neurophysiol. 43: 621–629, 1980.
 37. Bizzi, E., N. Hogan, F. A. Mussa‐Ivaldi, and S. Giszter. Does the nervous system use equilibrium‐point control to guide single and multiple joint movements? Behav. Brain Sci. 15: 603–613, 1992.
 38. Bloedel, J. R., V. Bracha, and P. S. Larson. Real time operations of the cerebellar cortex. Can. J. Neurol. Sci. 20 (Suppl. 3): S7–S18, 1993.
 39. Bosco, G., and R. E. Poppele. Broad directional tuning in spinal projections to the cerebellum. J. Neurophysiol. 70: 863–866, 1993.
 40. Bourbonnais, D., C. Krieger, and A. M. Smith. Cerebellar cortical activity during stretch of antagonist muscles. Can. J. Physiol. Pharmacol. 64: 1202–1213, 1986.
 41. Boyd, I. A. Intrafusal muscle fibres in the cat and their motor control. In: Feedback and Motor Control in Invertebrates and Vertebrates, edited by W. J. P. Barnes and M. H. Gladden. London: Croon Helm, 1985, p. 123–144.
 42. Boyd, I. A., and M. Gladden. Morphology of mammalian muscle spindles. Review. In: The Muscle Spindle, edited by I. A. Boyd and M. Gladden. London: Macmillan, 1985, p. 3–22.
 43. Boyd, I. A., P. R. Murphy, and V. A. Moss. Analysis of primary and secondary afferent responses to stretch during activation of the dynamic bag, fibre or the static bag2 fibre in cat muscle spindles. In: The Muscle Spindle, edited by I. A. Boyd and M. Gladden. London: Macmillan, 1985, p. 153–158.
 44. Boyd, I. A., and T. D. M. Roberts. Proprioceptive discharges from stretch receptors in the knee joint of the cat. J. Physiol. (Lond.) 122: 38–58, 1953.
 45. Brazier, M. A History of Neurophysiology in the 17th and 18th Centuries. New York: Raven, 1984, p. 230.
 46. Brazier, M. A History of Neurophysiology in the 19th Century. New York: Raven, 1988, p. 265.
 47. Brooke, J. D., and W. E. Mcllroy. Brain plans and servo loops in determining corrective movements. In: Multiple Muscle Systems: Biomechanics and Movement Organization, edited by J. M. Winters and S. L.‐Y. Woo. Berlin: Springer, 1990, p. 706–716.
 48. Brown, M. C., I. Engberg, and P. B. C. Matthews. Fusimotor stimulation and the dynamic sensitivity of the secondary ending of the muscle spindle. J. Physiol. (Lond.) 189: 545–550, 1967.
 49. Brown, M. C., G. M. Goodwin, and P. B. C. Matthews. After‐effects of fusimotor stimulation on the response of muscle spindle primary afferent endings. J. Physiol. (Lond.) 205: 677–694, 1969.
 50. Brown, T. G. The intrinsic factor in the act of progression in the mammal. Proc. R. Soc. Lond. B 84: 308–319, 1911.
 51. Buford, J. A., and J. L. Smith. Adaptive control for backward quadrupedal walking. II. Hindlimb muscle synergies. J. Neurophysiol. 64: 756–766, 1990.
 52. Burgess, P. R., and F. J. Clark. Characteristics of knee joint receptors in the cat. J. Physiol. (Lond.) 203: 317–335, 1969.
 53. Burke, D., S. C. Gandevia, and G. Macefield. Responses to passive movement of receptors in joint, skin and muscle of the human hand. J. Physiol. (Lond.) 402: 347–361, 1988.
 54. Burke, D., B. McKeon, N. F. Skuse, and R. A. Westerman. Anticipation and fusimotor activity in preparation for a voluntary contraction. J. Physiol. (Lond.) 306: 337–348, 1980.
 55. Burke, D., B. McKeon, and R. A. Westerman. Induced changes in the thresholds for voluntary activation of human spindle endings. J. Physiol. (Lond.) 302: 171–182, 1980.
 56. Burrows, M. Local circuits for the control of leg movements in an insect. Trends Neurosci. 15: 226–232, 1992.
 57. Bush, B. M. H. Non‐impulsive stretch receptors in crustaceans. In: Neurones Without Impulses, edited by A. Roberts and B. M. H. Bush. Cambridge: Cambridge University Press, 1981, p. 147–176.
 58. Butler, E. G., M. K. Home, and J. Rawson. Sensory characteristics of monkey thalamic and motor cortex neurones. J. Physiol. (Lond.) 445: 1–24, 1992.
 59. Buxton, D. F., and D. Peck. Neuromuscular spindles relative to joint movement complexities. Clin. Anat. 2: 211–224, 1989.
 60. Cabelguen, J.‐M. Static and dynamic fusimotor controls in various hindlimb muscles during locomotor activity in the decorticate cat. Brain Res. 213: 83–98, 1981.
 61. Capaday, C., and J. D. Cooke. The effect of muscle vibration on the attainment of intended final position during voluntary human arm movements. Exp. Brain Res. 42: 228–230, 1981.
 62. Capaday, C., R. Forget, R. Eraser, and Y. Lamarre. Evidence for a contribution of the motor cortex to the long‐latency stretch reflex of the human thumb. J. Physiol. (Lond.) 440: 243–255, 1991.
 63. Capaday, C., and R. B. Stein. Amplitude modulation of the soleus H‐reflex in the human during walking and standing. J. Neurosci. 6: 1308–1313, 1986.
 64. Capaday, C., and R. B. Stein. Difference in the amplitude of the human soleus H reflex during walking and running. J. Physiol. (Lond.) 392: 513–522, 1987.
 65. Carli, G., K. Diete‐Spiff, and O. Pompeiano. Responses of the muscle spindles and the extrafusal fibres in an extensor muscle to stimulation of the lateral vestibular nucleus in the cat. Arch. Ital. Biol. 105: 209–242, 1967.
 66. Carli, G., F. Farabollini, G. Fontani, and M. Meucci. Slowly adapting receptors in cat hip joint. J. Neurophysiol. 42: 767–778, 1979.
 67. Carlson Kuhta, P., and J. L. Smith. Scratch responses in normal cats: hindlimb kinematics and muscle synergies. J. Neurophysiol. 64: 1653–1667, 1990.
 68. Chen, W. J., and R. E. Poppele. Small‐signal analysis of response of mammalian muscle spindles with fusimotor stimulation and a comparison with large‐signal properties. J. Neurophysiol. 41: 15–27, 1978.
 69. Chin, N. K., M. Cope, and M. Pang. Number and distribution of spindle capsules in seven hindlimb muscles of the cat. In: Symposium on Muscle Receptors, edited by D. Barker. Hong Kong: Hong Kong University Press, 1962, p. 241–248.
 70. Cheney, P. D., and J. B. Preston. Classification and response characteristics of muscle spindle afferents in the primate. J. Neurophysiol. 39: 1–8, 1976.
 71. Clarac, F. Decapod crustacean leg coordination during walking. In: Locomotion and Energetics in Arthropods, edited by C. F. Herreid and C. R. Fourtner. New York: Plenum, 1982, p. 31–71.
 72. Clarac, F., and J. Ayers. Walking in Crustacea: motor program and peripheral regulation. J. Physiol. (Paris) 73: 523–542, 1977.
 73. Clark, F. J., R. C. Burgess, J. W. Chapin, and W. T. Lipscomb. Role of intramuscular receptors in the awareness of limb position. J. Neurophysiol. 54: 1529–1540, 1985.
 74. Cody, F. W. J., L. M. Harrison, and A. Taylor. Analysis of activity of muscle spindles of the jaw‐closing muscles during normal movements in the cat. J. Physiol. (Lond.) 253: 565–582, 1975.
 75. Cole, J. D., and E. M. Sedgwick. The perceptions of force and of movement in a man without large myelinated sensory afferents below the neck. J. Physiol. (Lond.) 449: 503–515, 1992.
 76. Collins, D. F., W. E. McIlroy, and J. D. Brooke. Contralateral inhibition of soleus H reflexes with different velocities of passive movement of the opposite leg. Brain Res. 603: 96–101, 1993.
 77. Collins, D. F., M. Gorassini, and A. Prochazka. Forelimb proprioceptors recorded during voluntary movements in cats. In: Alpha and Gamma Motor Systems, edited by A. Taylor and M. H. Gladden. London: Macmillan, 1995 (in press).
 78. Conway, B. A., H. Hultborn, and O. Kiehn. Proprioceptive input resets central locomotor rhythm in the spinal cat. Exp. Brain Res. 68: 643–656, 1987.
 79. Cooper, B. Y., D. S. Glendinning, and C. J. Vierck. Finger movement deficits in the stumptail macaque following lesions of the fasciculus cuneatus. Somatosens. Mot. Res. 10: 17–29, 1993.
 80. Cooper, S. The small motor nerves to muscle spindles and to extrinsic eye muscles. J. Physiol. (Lond.) 186: 28–29 P, 1966.
 81. Corda, M., C. V. Euler, and G. Lennerstrand. Reflex and cerebellar influences on alpha and “rhythmic” and “tonic” gamma activity in the intercostal muscle. J. Physiol. (Lond.) 184: 898–923, 1966.
 82. Crago, P. E., J. C. Houk, and Z. Hasan. Regulatory actions of human stretch reflex. J. Neurophysiol. 39: 925–935, 1976.
 83. Crago, P. E., J. C. Houk, and W. Z. Rymer. Sampling of total muscle force by tendon organs. J. Neurophysiol. 47: 1069–1083, 1982.
 84. Creed, R. S., D. Denny‐Brown, J. C. Eccles, E. G. T. Liddell, and C. S. Sherrington. In: Reflex Activity of the Spinal Cord. New York: Oxford University Press, 1972, p. 216.
 85. Critchlow, V., and C. V. Euler. Intercostal muscle spindle activity and its gamma motor control. J. Physiol. (Lond.) 168: 820–847, 1963.
 86. Cross, M. J., and D. I. McCloskey. Position sense following surgical removal of joints in man. Brain Res. 55: 443–445, 1973.
 87. Cussons, P. D., M. Hulliger, and P. B. C. Matthews. Effects of fusimotor stimulation on the response of the secondary endings of the muscle spindle to sinusoidal stretching. J. Physiol. (Lond.) 270: 835–850, 1977.
 88. Delcomyn, F. Perturbation of the motor system in freely walking cockroaches. I. Rear leg amputation and the timing of motor activity in leg muscles. J. Exp. Biol. 156: 483–502, 1991.
 89. Deliagina, T. G., A. G. Feldman, I. M. Gelfand, and G. N. Orlovsky. On the role of central program and afferent inflow in the control of scratching movements in the cat. Brain Res. 100: 297–313, 1975.
 90. Desmedt, J. E., and E. Godaux. Voluntary motor commands in human ballistic movements. Ann. Neurol. 5: 415–421, 1979.
 91. Diener, H. C., J. Dichgans, B. Guschlbauer, and H. Mau. The significance of proprioception on postural stabilization as assessed by ischaemia. Brain Res. 296: 103–109, 1984.
 92. Diener, H. C., F. B. Horak, and L. M. Nashner. Influence of stimulus parameters on human postural responses. J. Neurophysiol. 59: 1888–1905, 1988.
 93. Dietz, V., A. Gollhofer, M. Kleiber, and M. Trippel. Regulation of bipedal stance: dependency on “load” receptors. Exp. Brain Res. 89: 229–231, 1992.
 94. Dietz, V., M. Trippel, M. Discher, and G. A. Horstmann. Compensation of human stance perturbations: selection of the appropriate electromyographic pattern. Neurosci. Lett. 126: 71–74, 1991.
 95. Donga, R., A. Taylor, and P. J. W. Jüch. The use of midbrain stimulation to identify the discharges of static and dynamic fusimotor neurones during reflex jaw movements in the anaesthetized cat. Exp. Physiol. 78: 15–23, 1993.
 96. Drew, T. Motor cortical activity during voluntary gait modifications in the cat. I. Cells related to the forelimbs. J. Neurophysiol. 70: 179–199, 1993.
 97. Drew, T., and S. Rossignol. Forelimb responses to cutaneous nerve stimulation during locomotion in intact cats. Brain Res. 329: 323–328, 1985.
 98. Driankov, D., H. Hellendoorn, and M. Reinfrank. An Introduction to Fuzzy Control. New York: Springer, 1993, p. 316.
 99. Dufresne, J. R., J. F. Soechting, and C. A. Terzuolo. Modulation of the myotatic reflex gain in man during intentional movements. Brain Res. 193: 62–84, 1980.
 100. Durbaba, R., A. Taylor, J. F. Rodgers, and A. J. Fowle. Fusimotor effects of cerebellar outflow in the anaesthetized cat. J. Physiol. (Lond.) 479: 141–142 P, 1994.
 101. Dutia, M. B. The muscles and joints of the neck: their specialisation and role in head movement. Prog. Neurobiol. 37: 165–178, 1991.
 102. Duysens, J., and K. G. Pearson. Inhibition of flexor burst generation by loading ankle extensor muscles in walking cats. Brain Res. 187: 321–333, 1980.
 103. Dyhre‐Poulsen, P. Perception of tactile stimuli before ballistic and during tracking movements. In: Active Touch, edited by G. Gordon. Oxford: Pergamon, 1978, p. 171–176.
 104. Edin, B. B. Finger joint movement sensitivity of non‐cutaneous mechanoreceptor afferents in the human radial nerve. Exp. Brain Res. 82: 417–422, 1990.
 105. Edin, B. B. Quantitative analysis of static strain sensitivity in human mechanoreceptors from hairy skin. J. Neurophysiol. 67: 1105–1113, 1992.
 106. Edin, B. B., and J. H. Abbs. Finger movement responses of cutaneous mechanoreceptors in the dorsal skin of the human hand. J. Neurophysiol. 65: 657–670, 1991.
 107. Edin, B. B., and A. B. Vallbo. Dynamic response of human muscle spindle afferents to stretch. J. Neurophysiol. 63: 1297–1306, 1990.
 108. Edin, B. B., and A. B. Vallbo. Muscle afferent responses to isometric contractions and relaxations in humans. J. Neurophysiol. 63: 1307–1313, 1990.
 109. Eklund, G., K.‐E. Hagbarth, J. V. Hagglund, and E. U. Wallin. The “late” reflex responses to muscle stretch: the “resonance hypothesis” versus the “long‐loop hypothesis.” J. Physiol. (Lond.) 326: 79–90, 1982.
 110. Elble, R. J., M. H. Schieber, and W. T. Thach. Activity of muscle spindles, motor cortex and cerebellar nuclei during action tremor. Brain Res. 323: 330–334, 1984.
 111. Eldred, E., R. Granit, and P. A. Merton. Supraspinal control of the muscle spindle and its significance. J. Physiol. (Lond.) 122: 498–523, 1953.
 112. Emonet‐Dénand, F., and Y. Laporte. Observations on the effects on spindle primary endings of the stimulation at low frequency of dynamic β‐axons. Brain Res. 258: 101–104, 1983.
 113. Emonet‐Dénand, F., Y. Laporte, P. B. C. Matthews, and J. Petit. On the subdivision of static and dynamic fusimotor actions on the primary ending of the cat muscle spindle. J. Physiol. (Lond.) 268: 827–861, 1977.
 114. Emonet‐Dénand, F., J. Petit, and Y. Laporte. Comparison of skeleto‐fusimotor innervation in cat peroneus brevis and peroneus tertius muscles. J. Physiol. (Lond.) 458: 519–525, 1992.
 115. von Euler, C., and G. Peretti. Dynamic and static contributions to the rhythmic γ activation of primary and secondary spindle endings in external intercostal muscle. J. Physiol. (Lond.) 187: 501–516, 1966.
 116. Evarts, E. V., and C. Fromm. Sensory responses in motor cortex neurons during precise motor control. Neurosci. Lett. 5: 267–272, 1977.
 117. Evarts, E. V., Y. Shinoda, and S. P. Wise. Neurophysiological Approaches to Higher Brain Functions. New York: Wiley, 1984, p. 198.
 118. Ferrell, W. R. The adequacy of stretch receptors in the cat knee joint for signalling joint angle throughout a full range of movement. J. Physiol. (Lond.) 299: 85–100, 1980.
 119. Ferrell, W. R., R. H. Baxendale, C. Carnachan, and I. K. Hart. The influence of joint afferent discharge on locomotion, proprioception and activity in conscious cats. Brain Res. 347: 41–48, 1985.
 120. Ferrell, W. R., and A. Smith. The effect of loading on position sense at the proximal interphalangeal joint of the human finger. J. Physiol. (Lond.) 418: 145–161, 1989.
 121. Fetz, E. E. Are movement parameters recognizably coded in the activity of single neurons? Behav. Brain Sci. 15: 679–690, 1992.
 122. Fetz, E. E., D. V. Finocchio, M. A. Baker, and M. J. Soso. Sensory and motor responses of precentral cortex cells during comparable passive and active joint movements. J. Neurophysiol. 43: 1070–1089, 1980.
 123. Fitzpatrick, R. C., J. L. Taylor, and D. I. McCloskey. Ankle stiffness of standing humans in response to imperceptible perturbation: reflex and task‐dependent components. J. Physiol. (Lond.) 454: 533–547, 1992.
 124. Flament, D., P. A. Fortier, and E. Fetz. Response patterns and postspike effects of peripheral afferents in dorsal root ganglia of behaving monkeys. J. Neurophysiol. 67: 875–889, 1992.
 125. Forssberg, H., S. Grillner, J. Halbertsma, and S. Rossignol. The locomotion of the low spinal cat. II. Interlimb coordination. Acta Physiol. Scand. 108: 283–295, 1980.
 126. Forssberg, H., S. Grillner, and S. Rossignol. Phase dependent reflex reversal during walking in chronic spinal cats. Brain Res. 85: 103–107, 1975.
 127. French, A. Transduction mechanisms of mechanosensilla. Annu. Rev. Entomol. 33: 39–58, 1988.
 128. Fromm, C., S. P. Wise, and E. V. Evarts. Sensory response properties of pyramidal tract neurons in the precentral motor cortex and postcentral gyrus of the rhesus monkey. Exp. Brain Res. 54: 177–185, 1984.
 129. Gandevia, S. C. Illusory movements produced by electrical stimulation of low‐threshold muscle afferents from the hand. Brain 108: 965–981, 1985.
 130. Gandevia, S. C., and D. Burke. Effect of training on voluntary activation of human fusimotor neurons. J. Neurophysiol. 54: 1422–1429, 1985.
 131. Gandevia, S. C., and D. Burke. Does the nervous system depend on kinesthetic information to control natural limb movements? Behav. Brain Sci. 15: 614–632, 1992.
 132. Gellman, R., A. R. Gibson, and J. C. Houk. Inferior olivary neurons in the awake cat: detection of contact and passive body displacement. J. Neurophysiol. 54: 40–60, 1985.
 133. Ghez, C., J. Gordon, M. F. Ghilardi, C. N. Christakos, and S. E. Cooper. Roles of proprioceptive input in the programming of arm trajectories. Cold Spring Harb. Symp. Quant. Biol. 55: 837–847, 1990.
 134. Ghez, C., and Y. Shinoda. Spinal mechanisms of the functional stretch reflex. Exp. Brain Res. 32: 55–68, 1978.
 135. Gilman, S. The mechanism of cerebellar hypotonia. An experimental study in the monkey. Brain 92: 621–638, 1969.
 136. Giuliani, C. A., and J. L. Smith. Development and characteristics of airstepping in chronic spinal cats. J. Neurosci. 5: 1276–1282, 1985.
 137. Giuliani, C. A., and J. L. Smith. Stepping behaviors in chronic spinal cats with one hindlimb deafferented. J. Neurosci. 7: 2537–2546, 1987.
 138. Glendinning, D. S., B. Y. Cooper, C. J. Vierck, and C. M. Leonard. Altered precision grasping in stumptail macaques after fasciculus cuneatus lesions. Somatosens. Mot. Res. 9: 61–73, 1992.
 139. Godwin‐Austen, R. B. The mechanoreceptors of the costovertebral joints. J. Physiol. (Lond.) 202: 737–753, 1969.
 140. Goldberger, M. E. Locomotor recovery after unilateral hindlimb deafferentation in cats. Brain Res. 123: 59–74, 1977.
 141. Goodwin, G. M., M. Hulliger, and P. B. C. Matthews. The effects of fusimotor stimulation during small‐amplitude stretching on the frequency‐response of the primary ending of the mammalian muscle spindle. J. Physiol. (Lond.) 253: 175–206, 1975.
 142. Goodwin, G. M., and E. S. Luschei. Discharge of spindle afferents from jaw‐closing muscles during chewing in alert monkeys. J. Neurophysiol. 38: 560–571, 1975.
 143. Goodwin, G. M., D. I. McCloskey, and P. B. C. Matthews. The contribution of muscle afferents to kinaesthesia shown by vibration‐induced illusions of movement and by the effects of paralysing joint afferents. Brain 95: 705–748, 1972.
 144. Gorassini, M., A. Prochazka, G. W. Hiebert, and M. Gauthier. Adaptive responses to loss of ground support during walking. I. Intact cats. J. Neurophysiol. 71: 603–610, 1994.
 145. Gorassini, M., A. Prochazka, and J. Taylor. Cerebellar ataxia and muscle spindle sensitivity. J. Neurophysiol. 70: 1853–1862, 1993.
 146. Gossard, J.‐P., R. M. Brownstone, I. Barajon, and H. Hultborn. Transmission in a locomotor‐related group Ib pathway from hindlimb extensor muscles in the cat. Exp. Brain Res. 98: 213–228, 1994.
 147. Gottlieb, S., and A. Taylor. Interpretation of fusimotor activity in cat masseter nerve during reflex jaw movements. J. Physiol. (Lond.) 345: 423–438, 1983.
 148. Granit, R. The Basis of Motor Control. London: Academic, 1970, p. 346.
 149. Granit, R., B. Holmgren, and P. A. Merton. The two routes for excitation of muscle and their subservience to the cerebellum. J. Physiol. (Lond.) 130: 213–224, 1955.
 150. Granit, R., C. Job, and B. R. Kaada. Activation of muscle spindles in pinna reflex. Acta Physiol. Scand. 27: 161–168, 1952.
 151. Granit, R., and B. R. Kaada. Influence of stimulation of central nervous structures on muscle spindles in cat. Acta Physiol. Scand. 27: 130–160, 1952.
 152. Greer, J. J., and R. B. Stein. Fusimotor control of muscle spindle sensitivity during respiration in the cat. J. Physiol. (Lond.) 422: 245–264, 1990.
 153. Gregory, J. E., A. K. McIntyre, and U. Proske. Tendon organ afferents in the knee joint nerve of the cat. Neurosci. Lett. 103: 287–292, 1989.
 154. Gregory, J. E., D. L. Morgan, and U. Proske. Two kinds of resting discharge in cat muscle spindles. J. Neurophysiol. 66: 602–612, 1991.
 155. Gregory, J. E., and U. Proske. The responses of Golgi tendon organs to stimulation of different combinations of motor units. J. Physiol. (Lond.) 295: 251–262, 1979.
 156. Grigg, P., and B. J. Greenspan. Response of primate joint afferent neurons to mechanical stimulation of knee joint. J. Neurophysiol. 40: 1–8, 1977.
 157. Grillner, S. Locomotion in vertebrates: central mechanisms and reflex interaction. Physiol. Rev. 55: 247–304, 1975.
 158. Grillner, S., T. Hongo, and S. Lund. Descending monosynaptic and reflex control of γ‐motoneurones. Acta Physiol. Scand. 75: 592–613, 1969.
 159. Grillner, S., and S. Rossignol. On the initiation of the swing phase of locomotion in chronic spinal cats. Brain Res. 146: 269–277, 1978.
 160. Grillner, S., and P. Zangger. The effect of dorsal root transection on the efferent motor pattern in the cat's hindlimb locomotion. Acta Physiol. Scand. 120: 393–405, 1984.
 161. Hagbarth, K.‐E. Microneurography and applications to issues of motor control: Fifth Annual Stuart Reiner Memorial Lecture. Muscle Nerve 16: 693–705, 1993.
 162. Hagbarth, K.‐E., J. V. Hägglund, E. U. Wallin, and R. R. Young. Grouped spindle and electromyographic responses to abrupt wrist extension movements in man. J. Physiol. (Lond.) 312: 81–96, 1981.
 163. Hagbarth, K.‐E., and A. B. Vallbo. Afferent response to mechanical stimulation of muscle receptors in man. Acta Soc. Med. Upsalien 72: 102–104, 1967.
 164. Hammond, P. H., P. A. Merton, and G. G. Sutton. Nervous gradation of muscular contraction. Br. Med. Bull. 12: 214–218, 1956.
 165. Hasan, Z. A model of spindle afferent response to muscle stretch. J. Neurophysiol. 49: 989–1006, 1983.
 166. Hasan, Z., and J. C. Houk. Analysis of response properties of deefferented mammalian spindle receptors based on frequency response. J. Neurophysiol. 38: 663–672, 1975.
 167. Head, S. I., and B. M. H. Bush. Proprioceptive reflex interactions with central motor rhythms in the isolated thoracic ganglion of the shore crab. J. Comp. Physiol. [A] 168: 445–459, 1991.
 168. Heller, B. W., P. H. Veltink, N. J. M. Rijkhoff, W. L. C. Rutten, and B. J. Andrews. Reconstructing muscle activation during normal walking: a comparison of symbolic and connectionist machine learning techniques. Biol. Cybern. 69: 327–335, 1993.
 169. Hiebert, G., M. Gorassini, W. Jiang, A Prochazka, and K. G. Pearson. Adaptive responses to loss of ground support during walking. II. Comparison of intact and chronic spinal cats. J. Neurophysiol. 71: 611–622, 1994.
 170. Hoffer, J. A., A. A. Caputi, and I. E. Pose. Activity of muscle proprioceptors in cat posture and locomotion: relation to EMG, tendon force and the movement of fibres and aponeurotic segments. In: Muscle Afferents And Spinal Control of Movement, edited by L. Jami, E. Pierrot‐Deseilligny, and D. Zytnicki. London: Pergamon, 1992, p. 113–122.
 171. Hoffer, J. A., and M. K. Haugland. Signals from tactile receptors in glabrous skin for restoring motor function in paralyzed humans. In: Neural Prostheses: Replacing Motor function After Disease or Disability, edited by R. B. Stein, P. H. Peckham, and D. B. Popovic. New York: Oxford University Press, 1992, p. 91–125.
 172. Holm, W., D. Padeken, and S. S. Schäfer. Characteristic curves of the dynamic response of primary muscle spindle endings with and without gamma stimulation. Pflugers Arch. 391: 163–170, 1981.
 173. Horch, K. W., R. P. Tuckett, and P. R. Burgess. A key to the classification of cutaneous mechanoreceptors. J. Invest. Dermatol. 69: 75–82, 1977.
 174. Horcholle‐Bossavit, G., L. Jami, J. Petit, R. Vejsada, and D. Zytnicki. Ensemble discharge from Golgi tendon organs of cat peroneus tertius muscle. J. Neurophysiol. 64: 813–821, 1990.
 175. Houk, J., and E. Henneman. Responses of Golgi tendon organs to active contractions of the soleus muscle of the cat. J. Neurophysiol. 30: 466–481, 1967.
 176. Houk, J. C., W. Z. Rymer, and P. E. Crago. Dependence of dynamic response of spindle receptors on muscle length and velocity. J. Neurophysiol. 46: 143–166, 1981.
 177. Houk, J. C., and W. Simon. Responses of Golgi tendon organs to forces applied to muscle tendon. J. Neurophysiol. 30: 1466–1481, 1967.
 178. Hulliger, M. The mammalian muscle spindle and its central control. Rev. Physiol. Biochem. Pharmacol. 101: 1–110, 1984.
 179. Hulliger, M., F. Emonet‐Dénand, and T. K. Baumann. Enhancement of stretch sensitivity of cat primary spindle afferents by low‐rate static gamma action. In: The Muscle Spindle, edited by I. A. Boyd and M. H. Gladden. London: Macmillan, 1985, p. 189–193.
 180. Hulliger, M., P. B. C. Matthews, and J. Noth. Static and dynamic fusimotor stimulation on the response of Ia fibres to low frequency sinusoidal stretching of widely ranging amplitudes. J. Physiol. (Lond.) 267: 811–838, 1977.
 181. Hulliger, M., E. Nordh, A.‐E. Thelin, and A. B. Vallbo. The responses of afferent fibres from the glabrous skin of the hand during voluntary finger movements in man. J. Physiol. (Lond.) 291: 233–249, 1979.
 182. Hunt, C. C., and A. S. Paintal. Spinal reflex regulation of fusimotor neurones. J. Physiol. (Lond.) 143: 195–212, 1958.
 183. Iles, J. F., M. Stokes, and A. Young. Reflex actions of knee joint afferents during contraction of the human quadriceps. Clin. Physiol. 10: 489–500, 1990.
 184. Jacks, A., A. Prochazka, and P. St. J. Trend. Instability in human forearm movements studied with feedback‐controlled electrical stimulation of muscles. J. Physiol. (Lond.) 402: 443–461, 1988.
 185. Jami, L. Golgi tendon organs in mammalian skeletal muscle: functional properties and central actions. Physiol. Rev. 72: 623–666, 1992.
 186. Jami, L., and J. Petit. Fusimotor actions on sensitivity of spindle secondary endings to slow muscle stretch in cat peroneus tertius. J. Neurophysiol. 41: 860–869, 1978.
 187. Jankowska, E. Interneuronal relay in spinal pathways from proprioceptors. Prog. Neurobiol. 38: 335–378, 1992.
 188. Jansen, J. K. S., and T. Rudjord. On the silent period and Golgi tendon organs of the soleus muscle of the cat. Acta Physiol. Scand. 62: 364–379, 1964.
 189. Johansson, H., P. Sjölander, and P. Sojka. Receptors in the knee joint ligaments and their role in the biomechanics of the joint. CRC Crit. Rev. Biomed. Eng. 18: 341–368, 1991.
 190. Johansson, R. S., and A. B. Vallbo. Tactile sensibility in the human hand: relative and absolute densities of four types of mechanoreceptive units in glabrous skin. J. Physiol. (Lond.) 286: 283–300, 1979.
 191. Jovanovic, K., R. Anastasijevic, and J. Vuco. Reflex effects on gamma fusimotor neurones of chemically induced discharges in small‐diameter muscle afferents in decerebrate cats. Brain Res. 521: 89–94, 1990.
 192. Kalveram, K. T. A neural network model rapidly learning gains and gating of reflexes necessary to adapt to an arm's dynamics. Biol. Cybern. 68: 183–191, 1992.
 193. Kandel, E. R., J. H. Schwartz, and T. M. Jessell. Principles of Neural Science. New York: Elsevier, 1991, p. 1135.
 194. Karanjia, P. N., and J. H. Ferguson. Passive joint position sense after total hip replacement surgery. Ann. Neurol. 13: 654–657, 1983.
 195. Kirkwood, C. A., B. J. Andrews, and P. Mowforth. Automatic detection of gait events: a case study using inductive learning techniques. J. Biomed. Eng. 11: 511–516, 1989.
 196. Knibestöl, M., and A. B. Vallbo. Single unit analysis of mechanoreceptor activity from the human glabrous skin. Acta Physiol. Scand. 80: 178–195, 1970.
 197. Kornhuber, H. H., and L. Deecke. Hirnpotentialänderungen bei Willkürbewegungen und passiven Bewegungen des Menschen: Bereitschaftspotential und reafferente Potentiale. Pflugers Arch. 284: 1–17, 1965.
 198. Koshland, G. F., and J. L. Smith. Paw‐shake responses with joint immobilization: EMG changes with atypical feedback. Exp. Brain Res. 77: 361–373, 1989.
 199. Kosko, B., and S. Isaka. Fuzzy logic, Sci. Am. 269: 76–81, 1993.
 200. Kriellaars, R. M., B. R. Brownstone, D. J. Noga, and L. M. Jordan. Mechanical entrainment of fictive locomotion in the decerebrate cat. J. Neurophysiol. 71: 2074–2086, 1994.
 201. Kucera, J., and R. Hughes. Histological study of motor innervation to long nuclear chain intrafusal fibres in the muscle spindle of the cat. Cell Tiss. Res. 228: 535–547, 1983.
 202. Lacquaniti, F., N. A. Borghese, and M. Carrozzo. Transient reversal of the stretch reflex in human arm muscles. J. Neurophysiol. 66: 939–954, 1991.
 203. Landgren, S., and H. Silfvenius. Nucleus Z, the medullary relay in the projection path to the cerebral cortex of group I muscle afferents from the cat's hind limb. J. Physiol. (Lond.) 218: 551–571, 1971.
 204. Larson, C. R., D. V. Finocchio, A. Smith, and E. S. Luschei. Jaw muscle afferent firing during an isotonic jaw positioning task in the monkey. J. Neurophysiol. 50: 61–73, 1983.
 205. Laszlo, J. I., and P. J. Bairstow. Accuracy of movement, peripheral feedback and efference copy. J. Mot. Behav. 3: 241–252, 1971.
 206. Latash, M. L. Virtual trajectories, joint stiffness, and changes in the limb natural frequency during single‐joint oscillatory movements. Neuroscience 49: 209–220, 1992.
 207. Lee, R. G., J. T. Murphy, and W. G. Tatton. Long‐latency myotatic reflexes in man: mechanisms, functional significance, and changes in patients with Parkinson's disease or hemiplegia. In: Motor Control Mechanisms in Health and Disease, edited by J. E. Desmedt. New York: Raven, 1983, p. 489–508.
 208. Lennerstrand, G., and U. Thoden. Position and velocity sensitivity of muscle spindles in the cat. II. Dynamic fusimotor single‐fibre activation of primary endings. Acta Physiol. Scand. 74: 16–29, 1968.
 209. Lennerstrand, G., and U. Thoden. Muscle spindle responses to concomitant variations in length and in fusimotor activation. Acta Physiol. Scand. 74: 153–165, 1968.
 210. Levine, W. S., and G. E. Loeb. The neural control of limb movement. IEEE Control Sys. 12: 38–47, 1992.
 211. Libersat, F., F. Clarac, and S. Zill. Force‐sensitive mechanoreceptors of the dactyl of the crab: single‐unit responses during walking and evaluation of function. J. Neurophysiol. 57: 1618–1637, 1987.
 212. Libersat, F., S. Zill, and F. Clarac. Single‐unit responses and reflex effects of force‐sensitive mechanoreceptors of the dactyl of the crab. J. Neurophysiol. 57: 1601–1617, 1987.
 213. Lidierth, M., and R. Apps. Gating in the spino‐olivocerebellar pathways to the c1 zone of the cerebellar cortex during locomotion in the cat. J. Physiol. (Lond.) 430: 453–469, 1990.
 214. Llewellyn, M., J. Yang, and A. Prochazka. Human H‐reflexes are smaller in difficult beam walking than in normal treadmill walking. Exp. Brain Res. 83: 22–28, 1990.
 215. Loeb, G. E. Somatosensory unit input to the spinal cord during normal walking. Can. J. Physiol. Pharmacol. 59: 627–635, 1981.
 216. Loeb, G. E., M. J. Bak, and J. Duysens. Long‐term unit recording from somatosensory neurons in the spinal ganglia of the freely walking cat. Science 197: 1192–1194, 1977.
 217. Loeb, G. E., and J. Duysens. Activity patterns in individual hindlimb primary and secondary muscle spindle afferents during normal movements in unrestrained cats. J. Neurophysiol. 42: 420–440, 1979.
 218. Loeb, G. E., J. A. Hoffer, and C. A. Pratt. Activity of spindle afferents from cat anterior thigh muscles. I. Identification and patterns during normal locomotion. J. Neurophysiol. 54: 549–564, 1985.
 219. Lund, J. P., and B. Matthews. Responses of temporomandibular joint afferents recorded in the Gasserian ganglion of the rabbit to passive movements of the mandible. In: Oral‐Facial Sensory and Motor Functions, edited by Y. Kawamura. Tokyo: Quintessence, 1981, p. 153–160.
 220. Lund, J. P., K. Sasamoto, T. Murakami, and K. A. Olsson. Analysis of rhythmical jaw movements produced by electrical stimulation of motor‐sensory cortex of rabbits. J. Neurophysiol. 52: 1014–1029, 1984.
 221. Lund, J. P., A. M. Smith, B. J. Sessle, and T. Murakami. Activity of trigeminal alpha and gamma motoneurones and muscle afferents during performance of a biting task. J. Neurophysiol. 42: 710–725, 1979.
 222. Lundberg, A. Reflex Control of Stepping. Nansen Memorial Lecture V. Oslo: University Forlaget, 1969, p. 42.
 223. Lundberg, A. Function of the ventral spinocerebellar tract. A new hypothesis. Exp. Brain Res. 12: 317–330, 1971.
 224. Lundberg, A. Half‐centres revisited. In: Regulatory Functions of the CNS, Motion and Organization Principles, edited by J. Szentagothai, M. Palkovits, and J. Hamori. Budapest: Pergamon, 1980, p. 155–167.
 225. Macefield, G., S. C. Gandevia, and D. Burke. Perceptual responses to microstimulation of single afferents innervating joints, muscles and skin of the human hand. J. Physiol. (Lond.) 429: 113–129, 1990.
 226. Mackay, W. A., and J. T. Murphy. Cerebellar modulation of reflex gain. Prog. Neurobiol. 13: 361–417, 1979.
 227. MacPherson, J. M. Strategies that simplify the control of quadrupedal stance. II. Electromyographic activity. J. Neurophysiol. 60: 218–231, 1988.
 228. MacPherson, J. M., D. S. Rushmer, and D. C. Dunbar. Postural responses in the cat to unexpected rotations of the supporting surface: evidence for a centrally generated synergic organization. Exp. Brain Res. 62: 152–160, 1986.
 229. Magoun, H. W., and R. Rhines. An inhibitory mechanism in the bulbar reticular formation. J. Neurophysiol. 9: 165–171, 1946.
 230. Marchand, R., C. F. Bridgman, E. Schumpert, and E. Eldred. Association of tendon organs and muscle spindles in muscles of the cat's leg. Anat. Rec. 169: 23–32, 1971.
 231. Marsden, C. D., P. A. Merton, and H. B. Morton. The sensory mechanism of servo action in human muscle. J. Physiol. (Lond.) 265: 521–535, 1977.
 232. Marsden, C. D., J. C. Rothwell, and B. L. Day. Long‐latency automatic responses to muscle stretch in man: origin and function. In: Motor Control Mechanisms in Health and Disease, edited by J. E. Desmedt. New York: Raven, 1983, p. 509–539.
 233. Martin, J. H., and C. Ghez. Differential impairments in reaching and grasping produced by local inactivation within the forelimb representation of the motor cortex in the cat. Exp. Brain Res. 94: 429–443, 1993.
 234. Matsunami, K., and K. Kubota. Muscle afferents of trigeminal mesencephalic tract nucleus and mastication in chronic monkeys. Jpn. J. Physiol. 22: 545–555, 1972.
 235. Matthews, B. H. C. Nerve endings in mammalian muscle. J. Physiol. (Lond.) 78: 1–33, 1933.
 236. Matthews, P. B. C. The differentiation of two types of fusimotor fibre by their effects on the dynamic response of muscle spindle primary endings. Q. J. Exp. Physiol. 47: 324–333, 1962.
 237. Matthews, P. B. C. The response of de‐efferented muscle spindle receptors to stretching at different velocities. J. Physiol. (Lond.) 168: 660–678, 1963.
 238. Matthews, P. B. C. Mammalian Muscle Receptors and their Central Actions. London: Arnold, 1972, p. 630.
 239. Matthews, P. B. C. The human stretch reflex and the motor cortex. Trends Neurosci. 14: 87–91, 1991.
 240. Matthews, P. B. C., and R. B. Stein. The sensitivity of muscle spindle afferents to small sinusoidal changes of length. J. Physiol. (Lond.) 200: 723–743, 1969.
 241. Matthews, P. B. C., and R. B. Stein. The regularity of primary and secondary muscle spindle afferent discharges. J. Physiol. (Lond.) 202: 59–82, 1969.
 242. McCloskey, D. I., M. J. Cross, R. Honner, and E. K. Potter. Sensory effects of pulling or vibrating exposed tendons in man. Brain 106: 21–37, 1983.
 243. McCloskey, D. I., and A. Prochazka. The role of sensory information in the guidance of voluntary movement. Somatosens. Mot. Res. 11: 69–76, 1994.
 244. McCrea, D. A. Can sense be made of spinal interneuron circuits? Behav. Brain Sci. 15: 633–643, 1992.
 245. McIntyre, A. K., U. Proske, and D. J. Tracey. Afferent fibres from muscle receptors in the posterior nerve of the cat's knee joint. Exp. Brain Res. 33: 415–424, 1978.
 246. Miall, R. C., J. F. Stein, and D. J. Weir. The cerebellum as an adaptive Smith‐predictor in visuomotor control. Soc. Neurosci. Abstr. 15: 180, 1989.
 247. Milner, T. E., and C. Cloutier. Compensation for mechanically unstable loading in voluntary wrist movement. Exp. Brain Res. 94: 522–532, 1993.
 248. Moberg, E. The role of cutaneous afferents in position sense, kinaesthesia, and motor function of the hand. Brain 106: 1–19, 1983.
 249. Morgan, D. L., A. Prochazka, and U. Proske. The aftereffects of stretch and fusimotor stimulation on the responses of primary endings of cat muscle spindles. J. Physiol. (Lond.) 356: 465–478, 1984.
 250. Mott, F. W., and C. S. Sherrington. Experiments upon the influence of sensory nerves upon movement and nutrition of the limbs. Proc. R. Soc. Lond. B 57: 481–488, 1895.
 251. Munk, H. Ueber die Funktionen von Hirn und Rückenmark. Berlin: Hirschwald, 1909, p. 247–285.
 252. Murphy, P. R., and H. A. Martin. Fusimotor discharge patterns during rhythmic movements. Trends Neurosci. 16: 273–278, 1993.
 253. Murphy, P. R., R. B. Stein, and J. Taylor. Phasic and tonic modulation of impulse rates in motoneurons during locomotion in premammillary cats. J. Neurophysiol. 52: 228–243, 1984.
 254. Nashner, L. M. Adapting reflexes controlling the human posture. Exp. Brain Res. 26: 59–72, 1976.
 255. Nashner, L. M., M. Woollacott, and G. Tuma. Organization of rapid responses to postural and locomotor‐like perturbations of standing man. Exp. Brain Res. 36: 463–476, 1979.
 256. Nathan, P. W., M. C. Smith, and A. W. Cook. Sensory effects in man of lesions of the posterior columns and of some other afferent pathways. Brain 109: 1003–1041, 1986.
 257. Newsom Davis, J. The response to stretch of human intercostal muscle spindles studied in vitro. J. Physiol. (Lond.) 249: 561–579, 1975.
 258. Nielsen, J., and Y. Kagamihara. The regulation of disynaptic reciprocal Ia inhibition during co‐contraction of antagonistic muscles in man. J. Physiol. (Lond.) 456: 373–391, 1992.
 259. Padel, Y., and J. L. Relova. Somatosensory responses in the cat motor cortex. I. Identification and course of an afferent pathway. J. Neurophysiol. 66: 2041–2058, 1991.
 260. Partridge, L. D. Signal‐handling characteristics of load‐moving skeletal muscle. Am. J. Physiol. 210: 1178–1191, 1966.
 261. Patla, A. E. Visual control of human locomotion. In: Adaptability of Human Gait, edited by A. E. Patla. New York: Elsevier, 1991, p. 55–97.
 262. Pavlides, C., E. Miyashita, and H. Asanuma. Projection from the sensory to the motor cortex is important in learning motor skills in the monkey. J. Neurophysiol. 70: 733–741, 1993.
 263. Pearson, K. G. Common principles of motor control in vertebrates and invertebrates. Annu. Rev. Neurosci. 16: 265–297, 1993.
 264. Pearson, K. G., and D. F. Collins. Reversal of the influence of group Ib afferents from plantaris on activity in medial gastrocnemius muscle during locomotor activity. J. Neurophysiol. 70: 1009–1017, 1993.
 265. Pearson, K. G., and J. Duysens. Function of segmental reflexes in the control of stepping in cockroaches and cats. In: Neural Control of Locomotion, edited by R. M. Herman, S. Grillner, P. S. G. Stein, and D. G. Stuart. New York: Plenum, 1976, p. 519–537.
 266. Pearson, K. G., and J. M. Ramirez. Influence of input from the forewing stretch receptors on motoneurones in flying locusts. J. Exp. Biol. 151: 317–340, 1990.
 267. Perret, C., and P. Buser. Static and dynamic fusimotor activity during locomotor movements in the cat. Brain Res. 40: 165–169, 1972.
 268. Phillips, C. G. Motor apparatus of the baboon's hand. The Ferrier Lecture, 1968. Proc. R. Soc. Lond. B 173: 141–174, 1969.
 269. Phillips, C. L., and R. D. Harbor. Feedback Control Systems, 2nd ed. Englewood Cliffs, NJ: Prentice Hall, 1991, p. 664.
 270. Popovic, D., R. Tomovic, D. Tepavac, and L. Schwirtlich. Control aspects of active above‐knee prosthesis. Int. J. Man. Mach. Stud. 35: 751–767, 1991.
 271. Poppele, R. E. An analysis of muscle spindle behavior using randomly applied stretches. Neuroscience 6: 1157–1165, 1981.
 272. Poppele, R. E., and R. J. Bowman. Quantitative description of linear behavior of mammalian muscle spindles. J. Neurophysiol. 33: 59–72, 1970.
 273. Poppele, R. E., and W. R. Kennedy. Comparison between behavior of human and cat muscle spindles recorded in vitro. Brain Res. 75: 316–319, 1974.
 274. Pringle, J. W. S., and V. J. Wilson. The response of a sense organ to a harmonic stimulus. J. Exp. Biol. 29: 220–234, 1952.
 275. Prochazka, A. Muscle spindle function during normal movement. In: International Review of Physiology and Neurophysiology IV, edited by R. Porter. Baltimore: MTP University Park, 1981, p. 47–90.
 276. Prochazka, A. Chronic techniques for studying neurophysiology of movement in cats. In: Methods for Neuronal Recording in Conscious Animals (IBRO Handbook Ser.: Methods Neurosci. 4), edited by R. Lemon. New York: Wiley, 1983, p. 113–128.
 277. Prochazka, A. Sensorimotor gain control: a basic strategy of motor systems? Prog. Neurobiol. 33: 281–307, 1989.
 278. Prochazka, A. Ensemble inputs to α‐motoneurons during movement. In: The Motor Unit—Physiology, Diseases, Regeneration, edited by R. Dengler. Munich: Urban Schwarzenberg, 1990, p. 32–42.
 279. Prochazka, A. Comparison of natural and artificial control of movement. IEEE Trans. Rehab. Eng. 1: 7–17, 1993.
 280. Prochazka, A., and M. Hulliger. Muscle afferent function and its significance for motor control mechanisms during voluntary movements in cat, monkey and man. In: Motor Control Mechanisms in Health and Disease, edited by J. E. Desmedt. New York: Raven, 1983, p. 93–132.
 281. Prochazka, A., M. Hulliger, P. Trend, and N. Dürmüller. Dynamic and static fusimotor set in various behavioural contexts. In: Mechanoreceptors: Development, Structure and Function, edited by P. Hnik, T. Soukup, R. Vejsada, and J. Zelena. London: Plenum, 1988, p. 417–430.
 282. Prochazka, A., M. Hulliger, P. Zangger, and K. Appenteng. “Fusimotor set”: new evidence for α‐independent control of γ‐motoneurones during movement in the awake cat. Brain Res. 339: 136–140, 1985.
 283. Prochazka, A., P. Trend, M. Hulliger, and S. Vincent. Ensemble proprioceptive activity in the cat step cycle: towards a representative look‐up chart. In: Afferent Control of Posture and Locomotion, edited by J. H. J. Allum and M. Hulliger. Amsterdam: Elsevier, 1989b, Prog. Brain Res. 80: 61–74.
 284. Prochazka, A., and P. Wand. Muscle spindle responses to rapid stretching in normal cats. In: Muscle Receptors and Movement, edited by A. Taylor and A. Prochazka. London: Macmillan, 1981, p. 257–261.
 285. Proske, U. The Golgi tendon organ: properties of the receptor and reflex action of impulses arising from tendon organs. In: Int. Rev. Physiol. 25, Neurophysiol. IV, edited by R. Porter. Baltimore: MTP University Park, 1981, p. 127–171.
 286. Proske, U., D. L. Morgan, and J. E. Gregory. Thixotropy in skeletal muscle and in muscle spindles: A review. Prog. Neurobiol. 41: 705–721, 1993.
 287. Rack, P. M. H., and D. Westbury. Elastic properties of the cat soleus tendon and their functional importance. J. Physiol. (Lond.) 347: 479–495, 1984.
 288. Reinking, R. M., J. A. Stephens, and D. J. Stuart. The tendon organs of cat medial gastrocnemius: significance of motor unit type and size for the activation of Ib afferents. J. Physiol. (Lond.) 250: 491–512, 1975.
 289. Ribot, E., J.‐P. Roll, and J.‐P. Vedel. Efferent discharges recorded from single skeletomotor and fusimotor fibres in man. J. Physiol. (Lond.) 375: 251–268, 1986.
 290. Richmond, F. J. R., and V. C. Abrahams. Physiological properties of muscle spindles in dorsal neck muscles of the cat. J. Neurophysiol. 42: 604–617, 1979.
 291. Roberts, W. J., N. P. Rosenthal, and C. A. Terzuolo. A control model of stretch reflex. J. Neurophysiol. 34: 620–634, 1971.
 292. Roll, J. P., and J. P. Vedel. Kinesthetic role of muscle afferents in man, studied by tendon vibration and microneurography. Exp. Brain Res. 47: 177–190, 1982.
 293. Rothwell, J. C., S. C. Gandevia, and D. Burke. Activation of fusimotor neurones by motor cortical stimulation in human subjects. J. Physiol. (Lond.) 431: 743–756, 1990.
 294. Rothwell, J. C., M. M. Traub, B. L. Day, J. A. Obeso, P. K. Thomas, and C. D. Marsden. Manual motor performance in deafferented man. Brain 105: 515–542, 1982.
 295. Rudomin, P. Presynaptic inhibition of muscle spindle and tendon organ afferents in the mammalian spinal cord. Trends Neurosci. 13: 499–505, 1990.
 296. Rymer, W. Z., and A. D'Almeida. Joint position sense: the effects of muscle contraction. Brain 103: 1–22, 1980.
 297. Sanes, J. N., K.‐H. Mauritz, M. C. Dalakas, and E. V. Evarts. Motor control in humans with large‐fiber sensory neuropathy. Hum. Neurobiol. 4: 101–114, 1985.
 298. Sainburg, R. L., H. Poizner, and C. Ghez. Loss of proprioception produces deficits in interjoint coordination. J. Neurophysiol. 70: 2136–2147, 1993.
 299. Schäfer, S. S. The characteristic curves of the dynamic response of primary muscle spindle endings in the absence and presence of stimulation of fusimotor fibres. Brain Res. 59: 395–399, 1973.
 300. Schaafsma, A., E. Otten, and J. D. Van Willigen. A muscle spindle model for primary afferent firing based on a simulation of intrafusal mechanical events. J. Neurophysiol. 65: 1297–1312, 1991.
 301. Schieber, M. H., and W. T. Thach. Alpha‐gamma dissociation during slow tracking movements of the monkey's wrist: preliminary evidence from spinal ganglion recording. Brain Res. 202: 213–216, 1980.
 302. Schieber, M. H., and W. T. Thach. Trained slow tracking. II. Bidirectional discharge patterns of cerebellar nuclear, motor cortex, and spindle afferent neurons. J. Neurophysiol. 54: 1228–1270, 1985.
 303. Schlapp, M. Observations on a voluntary tremor—violinist's vibrato. Q. J. Exp. Physiol. 58: 357–368, 1973.
 304. Scott, J. J. A., J. E. Gregory, U. Proske, and D. L. Morgan. Correlating resting discharge with small signal sensitivity and discharge variability in primary endings of cat soleus muscle spindles. J. Neurophysiol. 71: 309–316, 1994.
 305. Scott, S. H., and G. E. Loeb. The computation of position sense from spindles in mono‐ and multiarticular muscles. J. Neurosci. 14: 7529–7540, 1995.
 306. Sears, T. A. Efferent discharges in alpha and fusimotor fibres of intercostal nerves of the cat. J. Physiol. (Lond.) 174: 295–315, 1964.
 307. Sechenov, I. M. Refleksy Golovnogo Mozga (1863) English Translation: Reflexes of the Brain. In: I. M. Sechenov, Selected Works, by A. A. Subkov. Moscow: State Publ. House Biol. Med. Lit., 1935, p. 264–322.
 308. Severin, F. V. The role of the gamma motor system in the activation of the extensor alpha motor neurones during controlled locomotion. Biophysics 15: 1138–1145, 1970.
 309. Severin, F. V., G. N. Orlovsky, and M. L. Shik. Work of the muscle receptors during controlled locomotion. Biophysics 12: 575–586, 1967.
 310. Sinclair, R. J., and H. Burton. Neuronal activity in the second somatosensory cortex of monkeys (Macaca mulatta) during active touch of gratings. J. Neurophysiol. 70: 331–350, 1993.
 311. Sinkjaer, T., E. Toft, S. Andreassen, and B. C. Hornemann. Muscle stiffness in human ankle dorsiflexors: intrinsic and reflex components. J. Neurophysiol. 60: 1110–1121, 1988.
 312. Sjöström, A., and P. Zangger. Alpha‐gamma‐linkage in the spinal generator for locomotion in the cat. Acta Physiol. Scand. 94: 130–132, 1975.
 313. Smith, A. M., C. Dugas, P. Fortier, J. Kalaska, and N. Picard. Comparing cerebellar and motor cortical activity in reaching and grasping. Can. J. Neurol. Sci. 20 (Suppl. 3): S53–S61, 1993.
 314. Smith, J. L., M. G. Hoy, G. F. Koshland, D. M. Phillips, and R. F. Zernicke. Intralimb coordination of the paw‐shake response: a novel mixed synergy. J. Neurophysiol. 54: 1271–1281, 1985.
 315. Smith, O. J. M. A controller to overcome dead time. ISA J. 6: 28–33, 1959.
 316. St‐Onge, N., H. Qi, and A. G. Feldman. The patterns of control signals underlying elbow joint movements in humans. Neurosci. Lett. 164: 171–174, 1993.
 317. Strick, P. L. The influence of motor preparation on the response of cerebellar neurons to limb displacements. J. Neurosci. 3: 2007–2020, 1983.
 318. Struppler, A., and F. Erbel. Analysis of proprioceptive excitability with special reference to the “unloading reflex.” In: Neurophysiology Studied in Man, edited by G. Somjen. Amsterdam: Excerpta Medica, Ex. Med. Congr. Ser. 253, 1972, p. 298–304.
 319. Stuart, D. G., G. E. Goslow, C. G. Mosher, and R. M. Reinking. Stretch responsiveness of Golgi tendon organs. Exp. Brain Res. 10: 463–476, 1970.
 320. Stuart, D. G., C. G. Mosher, R. L. Gerlach, and R. M. Reinking. Mechanical arrangement and transducing properties of Golgi tendon organs. Exp. Brain Res. 14: 274–292, 1972.
 321. Taub, E., I. A. Goldberg, and P. Taub. Deafferentation in monkeys: pointing at a target without visual feedback. Exp. Neurol. 46: 178–186, 1975.
 322. Taylor, A., and F. W. J. Cody. Jaw muscle spindle activity in the cat during normal movements of eating and drinking. Brain Res. 71: 523–530, 1974.
 323. Taylor, A., and R. Donga. Central mechanisms of selective fusimotor control. In: Afferent Control of Posture and Movement, edited by J. H. J. Allum and M. Hulliger. Amsterdam: Elsevier, 1989, p. 27–36.
 324. Taylor, A., R. Donga, and P. J. W. Jüch. Fusimotor effects of midbrain stimulation on jaw muscle spindles of the anaesthetized cat. Exp. Brain Res. 93: 37–45, 1993.
 325. Taylor, A., and S. Gottlieb. Convergence of several sensory modalities in motor control. In: Feedback and Motor Control in Invertebrates and Vertebrates, edited by W. J. P. Barnes and M. H. Gladden. London: Croon Helm, 1985, p. 77–92.
 326. Taylor, A., J. F. Rodgers, A. J. Fowle, and R. Durbaba. The effect of succinylcholine on cat gastrocnemius muscle spindle afferents of different types. J. Physiol. (Lond.) 456: 629–644, 1992.
 327. Taylor, J. L., and D. I. McCloskey. Proprioception in the neck. Exp. Brain Res. 70: 351–360, 1988.
 328. Teasdale, N., R. Forget, C. Bard, J. Paillard, M. Fleury, and Y. Lamarre. The role of afferent information for the production of isometric forces and for handwriting tasks. Acta Psychol. 82: 179–191, 1993.
 329. Thach, W. T., H. P. Goodkin, and J. G. Keating. The cerebellum and the adaptive coordination of movement. Annu. Rev. Neurosci. 15: 403–442, 1992.
 330. Thach, W. T., J. G. Perry, and M. H. Schieber. Cerebellar output: body images and muscle spindles. Exp. Brain Res. 6 (Suppl.): 440–454, 1982.
 331. Tomovic, R., and R. McGhee. A finite state approach to the synthesis of control systems. IEEE Trans. Hum. Fac. Electron. 7: 122–128, 1966.
 332. Tracey, D. J. Characteristics of wrist joint receptors in the cat. Exp. Brain Res. 34: 165–176, 1979.
 333. Trend, P. Gain control in proprioceptive reflex pathways. Ph.D. thesis, University of London, 1987.
 334. Vallbo, A. B. Afferent discharge from human muscle spindles in non‐contracting muscles. Steady state impulse frequency as a function of joint angle. Acta Physiol. Scand. 90: 303–318, 1974.
 335. Vallbo, A. B. Sensations evoked from the glabrous skin of the human hand by electrical stimulation of unitary mechanosensitive afferents. Brain Res. 215: 359–363, 1981.
 336. Vallbo, A. B., and N. A. Al‐Falahe. Human muscle spindle response in a motor learning task. J. Physiol. (Lond.) 421: 553–568, 1990.
 337. Van Kan, P. L. E., A. R. Gibson, and J. C. Houk. Movement‐related inputs to intermediate cerebellum of the monkey. J. Neurophysiol. 69: 74–94, 1993.
 338. Vedel, J. P. Cortical control of dynamic and static gamma motoneurone activity. In: New Developments in Electromyography and Clinical Neurophysiology, edited by J. E. Desmedt. Basel: Karger, 1973, p. 126–135.
 339. Von Hoist, E. Relations between the central nervous system and the peripheral organs. Br. J. Anim. Behav. 2: 89–94, 1954.
 340. Voss, H. Tabelle der absoluten und relativen Muskelspindelzahlen der menschlichen Skelettmuskulatur. Anat. Am. 129: 562–572, 1971.
 341. Wall, P. D., and S. B. McMahon. Microneurography and its relation to perceived sensation. A critical review. Pain 21: 209–229, 1985.
 342. Walmsley, B., J. A. Hodgson, and R. E. Burke. Forces produced by medial gastrocnemius and soleus muscles during locomotion in freely moving cats. J. Neurophysiol. 41: 1203–1216, 1978.
 343. Walmsley, B., and U. Proske. Comparison of stiffness of soleus and medial gastrocnemius muscles in cats. J. Neurophysiol. 46: 250–259, 1981.
 344. Wand, P., A. Prochazka, and K.‐H. Sontag. Neuromuscular responses to gait perturbations in freely moving cats. Exp. Brain Res. 38: 109–114, 1980.
 345. Wand, P., M. Schwarz, W. Kolasiewicz, and K.‐H. Sontag. Nigral output neurons are engaged in regulation of static fusimotor action onto flexors in cats. Pflugers Arch. 391: 255–257, 1981.
 346. Wei, J. Y., B. R. Kripke, and P. R. Burgess. Classification of muscle spindle receptors. Brain Res. 370: 119–126, 1986.
 347. Wei, J. Y., J. Simon, M. Randic, and P. R. Burgess. Joint angle signalling by muscle spindle receptors. Brain Res. 370: 108–118, 1986.
 348. Wiesendanger, M., and T. S. Miles. Ascending pathway of low‐threshold muscle afferents to the cerebral cortex and its possible role in motor control. Physiol. Rev. 62: 1234–1270, 1982.
 349. Willis, W. D., and R. E. Coggeshall. Sensory Mechanisms of the Spinal Cord, 2nd ed. New York: Plenum, 1991, p. 575.
 350. Wilson, D. M. The central nervous control of flight in a locust. J. Exp. Biol. 38: 471–479, 1961.
 351. Wilson, D. M., and E. Gettrup. A stretch reflex controlling wing‐beat frequency in grasshoppers. J. Exp. Biol. 40: 171–185, 1963.
 352. Young, R. R., and K.‐E. Hagbarth. Physiological tremor enhanced by manoeuvres affecting the segmental stretch reflex. J. Neurol. Neurosurg. Psychiatry 43: 248–256, 1980.
 353. Zalkind, V. I. Method for an adequate stimulation of receptors of the cat carpo‐radialis joint. Sechenov Physiol. J. USSR, 57: 1123–1127, 1971.
 354. Zelena, J., and T. Soukup. The in‐series and in‐parallel components in rat hindlimb tendon organs. Neuroscience 9: 899–910, 1983.
 355. Zill, S. Proprioceptive feedback and the control of cockroach walking. In: Feedback and Motor Control in Invertebrates and Vertebrates, edited by W. J. P. Barnes and M. H. Gladden. London: Croon Helm, 1985, p. 187–208.

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How to Cite

Arthur Prochazka. Proprioceptive Feedback and Movement Regulation. Compr Physiol 2011, Supplement 29: Handbook of Physiology, Exercise: Regulation and Integration of Multiple Systems: 89-127. First published in print 1996. doi: 10.1002/cphy.cp120103