The reflex response to sinusoidal stretching of soleus in the decerebrate cat

Jansen, J. K. S.; Rack, P. M. H.

doi:10.1113/jphysiol.1966.sp007849

Cited by 42 publications

(27 citation statements)

References 23 publications

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“…the same result as would an afferent signal whose maximum was earlier in the cycle (Jansen & Rack, 1966;Westbury, 1971).…”

Section: T I H Brown P M H Rack and H F Rosssupporting

confidence: 65%

Electromyographic responses to imposed sinusoidal movement of the human thumb.

Brown¹,

Rack²,

Ross³

1982

The Journal of Physiology

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SUMMARY1. The interphalangeal joint of the thumb was driven through sinusoidal flexionextension movements while electromyograms were recorded from over the flexor pollicis longus muscle.2. When the subject relaxed his thumb the movement generated no detectable e.m.g. response. When, however, he exerted a voluntary flexing force electrical activity could be recorded from the flexor pollicis longus, the amplitude of which was modulated at the frequency of the movement.3. As the driving frequency was increased, the maximal e.m.g. activity occurred progressively later in the cycle of movement; for frequencies above about 6 Hz the timing of the averaged e.m.g. was compatible with a reflex delay of 55-65 msec.4. The frequency-phase plot was not, however, the perfect straight line that would arise from a simple and constant reflex delay. There were some consistent departures from linearity and some random variations. In either case, the timing of the e.m.g. and the timing of the reflex force (Brown, Rack & Ross, 1982a) changed together in ways that increased confidence in each of the measurements.5. The amplitude of the e.m.g. signal was more deeply modulated by movements at 8-14 Hz than by higher or lower frequencies, and it was concluded that the stretch reflex responds particularly readily to signals in that frequency range.

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“…the same result as would an afferent signal whose maximum was earlier in the cycle (Jansen & Rack, 1966;Westbury, 1971).…”

Section: T I H Brown P M H Rack and H F Rosssupporting

confidence: 65%

Electromyographic responses to imposed sinusoidal movement of the human thumb.

Brown¹,

Rack²,

Ross³

1982

The Journal of Physiology

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“…Examination of the raw data confirmed that this pattern was seen in all cases where harmonics of the stretching frequency were present. Studies in the cat have shown similar discrete bursts of activity phase-locked to cyclic stretching which became more probable as the amplitude of the stretch increased (Jansen and Rack 1966;Rosenthal et al 1970) and human studies also have shown EMG traces in which such saturation was apparent (e.g. Brown et al 1982b).…”

Section: Discussionmentioning

confidence: 98%

Entrainment to extinction of physiological tremor by spindle afferent input

2005

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In this study the systematic modulation of wrist flexor muscle activity by imposed joint movement was examined. Ten subjects maintained a constant contraction level (25% of maximum; trial duration: 20 s) in flexor carpi radialis while their wrists were perturbed with 50 different quasi-sinusoidal signals (frequency range: 0.5 -9.5 Hz; amplitude: 0.3° -4.2°). Frequency spectra of wrist position and the rectified and filtered electromyogram (EMG) were determined. The muscle activity was only weakly entrained to imposed movements of small amplitude and low frequency, as shown by a small peak in the EMG spectrum at the frequency of movement, while the most prominent peak in the spectrum was between 9 -15 Hz, corresponding to the frequency range of physiological tremor. The entrainment of muscle activity increased markedly as the amplitude and frequency of the imposed movement increased, to the point of saturation of modulation and harmonic peaks in the spectrum. In parallel with this increase in entrainment, the 9 -15 Hz tremor peak was progressively extinguished. The results are consistent with a coupled oscillator model in which the central oscillatory source(s) of tremor became fully entrained to the imposed movement at the highest amplitudes and frequencies. Such coupling depends on communication between the external forcing oscillator and the central oscillator(s), the Ia afferent signal from the imposed movement being the most likely candidate to provide the entraining signal for the central oscillator(s).

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“…5) there was a phase delay of force on position; the joint then exhibited a negative viscous stiffness, with flexor muscles exerting more force while they were shortening than when they were being forcibly extended. This phase delay of force on position never occurs in a passive mechanical system, and it does not occur when continuously activated mammalian muscles are subjected to sinusoidal movements in this range of frequencies and amplitudes (Rack, 1966); it may be regarded as proof of the reflex response to the movement (Jansen & Rack, 1966;.…”

Section: Discussionmentioning

confidence: 99%

Forces generated at the thumb interphalangeal joint during imposed sinusoidal movements

Brown

Rack

Ross

1982

The Journal of Physiology

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SUMMARY1. A method is described for driving the interphalangeal joint of the thumb through repeated sinusoidal flexion-extension movements, while immobilizing other joints of the wrist and hand.2. The joint met the sinusoidal movement with a force that fluctuated in an approximately sinusoidal manner. This paper is concerned with the relationship between the position and force sinusoids.3. When the thumb was relaxed the forces were small, but when the flexor pollicis longus was tetanically stimulated there was a large force change in response to each cycle of the movement. In either case, the maximum resistance to extension occurred during the later part of the extension movement, some 20O45O in advance of maximum extension. A similar result was obtained when the subject exerted a maximal voluntary flexing force.4. The resistance to movement can conveniently be displayed as a stiffness vector, the amplitude of which is the force/displacement, and the phase is the angle by which the force sinusoid leads the position sinusoid.5. When the subject maintained a continuous, though sub-maximal, flexing effort the timing of the force fluctuations changed with changing frequency of movement in a characteristic way, and the stiffness vectors described a C-shaped or spiral path. With increasing frequency the stiffness vectors moved round this path in a clockwise direction.6. For descriptive purposes the resistance to movement can usefully be regarded as the vector sum of a reflex and a non-reflex component. Since the reflex pathway involves significant conduction delays, the reflex force can be expected to appear later in the cycle of a higher frequency movement, and give rise to a vector which moves round in a clockwise direction as the frequency increases. The non-reflex stiffness, however, changes much less with frequency.7. It is concluded that the size of the C-shaped or spiral vector path gives an indication of the strength of the reflex activity, while the position of the high frequency points gives an indication of the noni-reflex resistance to the movement.

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The reflex response to sinusoidal stretching of soleus in the decerebrate cat

Cited by 42 publications

References 23 publications

Electromyographic responses to imposed sinusoidal movement of the human thumb.

Electromyographic responses to imposed sinusoidal movement of the human thumb.

Entrainment to extinction of physiological tremor by spindle afferent input

Forces generated at the thumb interphalangeal joint during imposed sinusoidal movements

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