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Proprioceptive Feedback and Movement Regulation

Arthur Prochazka

10.1002/cphy.cp120103

Source: Supplement 29: Handbook of Physiology, Exercise: Regulation and Integration of Multiple Systems

Originally published: 1996

Published online: January 2011

Full Article on Wiley Online Library



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. 79
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 160
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. 193 and Zelena and Soukup 354
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 278
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 341.] 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. 302.] 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 276
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. 33
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 302
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. 283
Figure 9. Figure 9.

Same Ia data as in Figure 8, 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 2. 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 108
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. (4
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. 281
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 343.

A Adapted from Edin and Vallbo 108, B from Appenteng and Prochazka 15
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 105
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 243
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 279


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. 79


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 160


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. 193 and Zelena and Soukup 354


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 278


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 341.] 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. 302.] 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 276


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. 33


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 302


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. 283


Figure 9.

Same Ia data as in Figure 8, 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 2. 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 108


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. (4


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. 281


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 343.

A Adapted from Edin and Vallbo 108, B from Appenteng and Prochazka 15


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 105


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 243


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 279
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Article Title: Proprioceptive Feedback and Movement Regulation
 

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