The Fusimotor System

1995 ◽  
pp. 259-270 ◽  
Author(s):  
K-E. Hagbarth ◽  
V. G. Macefield
Keyword(s):  
Fusimotor System

#22: FUSIMOTOR SYSTEM INVOLVEMENT IN THE TRANQUILIZER EFFECT OF EXERCISE

1981 ◽  
Vol 13 (2) ◽  
pp. 78
Author(s):  
H. A. deVries ◽  
C. P. Simard ◽  
R. A. Wiswell ◽  
E. Heckathorae ◽  
V. Carabetta
Keyword(s):  
System Involvement ◽  
Fusimotor System

Role of the Fusimotor System in Locomotion

2002 ◽  
pp. 335-342 ◽  
Author(s):  
Peter Ellaway ◽  
Anthony Taylor ◽  
Rade Durbaba ◽  
Stephen Rawlinson
Keyword(s):  
Fusimotor System

Activity of spindle afferents from cat anterior thigh muscles. III. Effects of external stimuli

1985 ◽  
Vol 54 (3) ◽  
pp. 578-591 ◽  
Author(s):  
G. E. Loeb ◽  
J. A. Hoffer ◽  
W. B. Marks
Keyword(s):  
Motor Program ◽  
Sartorius Muscle ◽  
Muscle Spindle Afferents ◽  
Implanted Electrodes ◽  
Hamstring Muscles ◽  
Highly Sensitive ◽  
Motoneuron Activity ◽  
Fusimotor System ◽  
External Stimuli ◽  
Awake Cats

Chronically implanted electrodes were used to record the activity of identified single muscle spindle afferents in awake cats during responses to various types of manual and electrical stimulation. During vigorous cyclical responses such as shaking and scratching, spindle afferents generally maintained at least some activity during both lengthening and shortening of the parent muscle, indicating that the programs for these movements include both extra- and intrafusal recruitment. During noncyclical responses such as ipsilateral limb withdrawal and crossed-extension, spindle activity was modest and poorly correlated with extrafusal activity. Weak cutaneous nerve shocks during walking elicited complex excitatory and inhibitory phase-dependent reflexes in the various muscles studied but caused relatively little change in spindle afferent activity, indicating a lack of correlation between alpha and gamma motoneuron activity. A primary and a secondary afferent from sartorius muscle were recorded simultaneously during walking cycles that were perturbed by electrically induced twitches of the antagonist hamstring muscles; both demonstrated highly sensitive, short latency responses to the resulting skeletal motion, consistent with their previously suggested roles in detecting small brief mechanical perturbations. The degree to which fusimotor responses were correlated with extrafusal responses to somatosensory perturbations was highly dependent on the specific nature of the stimulus and the response. Fusimotor reprogramming of the spindle sensitivity appears to be a feature of cyclical movements that are presumably under proprioceptive control, whereas brief perturbations within the context of a particular motor program may be ignored by the fusimotor system.

Proprioception during voluntary movement

1986 ◽  
Vol 64 (4) ◽  
pp. 499-504 ◽  
Author(s):  
Arthur Prochazka
Keyword(s):  
Human Subjects ◽  
Tonic Component ◽  
Divergence Of Opinion ◽  
Significant Divergence ◽  
Length Changes ◽  
Low Levels ◽  
Fusimotor System ◽  
Awake Cats ◽  
Tendon Organ ◽  
Shortening Contractions

In the last decade, a number of laboratories have accumulated data on the firing of single afferent fibres from muscle and skin during movement in awake cats, monkeys and human subjects. While there is general agreement on the firing behaviour of skin afferents and tendon organ (Ib) afferents during movement, there remains a significant divergence of opinion regarding the way in which the response of muscle spindle afferents (Ia and II) to length changes is modified by fusimotor action (e.g., alpha–gamma linkage versus "fusimotor set"). The controversies surrounding the fusimotor system have tended to overshadow the emergence of several important characteristics of propioceptive behaviour, corroborated in separate laboratories, (i) Mean la firing rates during active movements are nearly always higher than at rest. Thus, activation of the fusimotor system is reserved for the control of, or preparation for, movement. In animals, there is now strong evidence that there is usually a tonic component of fusimotor action during rhythmical movements. (ii) During fast, unloaded movements (peak muscle speeds, 0.2 resting lengths/s or more), the firing of both la and II afferents usually increases during lengthening and decreases during shortening. Ib afferents fire during even the most rapid active shortening of their parent muscles, (iii) During powerful shortening contractions performed against significant loads, la firing is often appreciable, suggesting that there is at least some underlying alpha–gamma coactivation. (iv) During fast imposed muscle stretches, la afferents respond with segmented bursts of firing (threshold speed for segmentation, 0.5–1.0 resting length/s). Ib afferents show far less segmentation of discharge under similar circumstances, (v) There are substantial numbers of tendon organ receptors which fire during tasks involving low levels of force.

Vestibular inputs do not influence the fusimotor system in relaxed muscles of the human leg

2007 ◽  
Vol 180 (1) ◽  
pp. 97-103 ◽  
Author(s):  
Leah R. Bent ◽  
P. S. Bolton ◽  
V. G. Macefield
Keyword(s):  
Fusimotor System

scholarly journals Role of the human fusimotor system in a motor adaptation task.

1988 ◽  
Vol 401 (1) ◽  
pp. 77-95 ◽  
Author(s):  
N A Al-Falahe ◽  
A B Vallbo
Keyword(s):  
Motor Adaptation ◽  
Fusimotor System ◽  
Adaptation Task

Balance Recovery in Cerebellar Patients: Evidence for a Contribution of the Fusimotor System

1995 ◽  
pp. 396-398
Author(s):  
M. C. Do ◽  
B. Bussel ◽  
Ph. Thoumie ◽  
O. Remy-Neris
Keyword(s):  
Balance Recovery ◽  
Fusimotor System

Implications of Positive Feedback in the Control of Movement

1997 ◽  
Vol 77 (6) ◽  
pp. 3237-3251 ◽  
Author(s):  
Arthur Prochazka ◽  
Deborah Gillard ◽  
David J. Bennett
Keyword(s):  
Positive Feedback ◽  
Force Feedback ◽  
Automatic Gain Control ◽  
Gain Control ◽  
Neuromuscular Control ◽  
Load Compensation ◽  
Tension Properties ◽  
Fusimotor System ◽  
Analytic Models ◽  
Positive Force

Prochazka, Arthur, Deborah Gillard, and David J. Bennett. Implications of positive feedback in the control of movement. J. Neurophysiol. 77: 3237–3251, 1997. In this paper we review some theoretical aspects of positive feedback in the control of movement. The focus is mainly on new theories regarding the reflexive role of sensory signals from mammalian tendon organ afferents. In static postures these afferents generally mediate negative force feedback. But in locomotion there is evidence of a switch to positive force feedback action. Positive feedback is often associated with instability and oscillation, neither of which occur in normal locomotion. We address this paradox with the use of analytic models of the neuromuscular control system. It is shown that positive force feedback contributes to load compensation and is surprisingly stable because the length-tension properties of mammalian muscle provide automatic gain control. This mechanism can stabilize control even when positive feedback is very strong. The models also show how positive force feedback is stabilized by concomitant negative displacement feedback and, unexpectedly, by delays in the positive feedback pathway. Other examples of positive feedback in animal motor control systems are discussed, including the β-fusimotor system, which mediates positive feedback of displacement. In general it is seen that positive feedback reduces the sensitivity of the controlled extremities to perturbations of posture and load. We conclude that positive force feedback can provide stable and effective load compensation that complements the action of negative displacement and velocity feedback.

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