A control model of stretch reflex.

Roberts, William J.; Rosenthal, N P; Terzuolo, C

doi:10.1152/jn.1971.34.4.620

Cited by 27 publications

(5 citation statements)

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“…However, if the end point is to make the behavioural experiments compatible with the many experiments which have been done on the various subelements of the postural control system (cf. Rosenthal, McKean, Roberts & Terzuolo, 1970;Roberts, Rosenthal & Terzuolo, 1971;Fernandez & Goldberg, 1971;Melvill Jones & Milsum, 1971), then use of sinusoidal disturbance and direct measurement of the frequency response is appropriate. Finally, if the end point of the research is to provide reliable means of quantifying clinical signs of altered nervous system function (Talbott, 1973), then the highly predictable nature of a sinusoidal signal becomes desirable.…”

Section: Discussionmentioning

confidence: 99%

The postural response of normal dogs to sinusoidal displacement

Brookhart¹,

Talbott²

1974

The Journal of Physiology

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SUMMARY1. Normal dogs were trained to adopt a laterally symmetric stance on a horizontal platform. Sinusoidal oscillation of the platform in the cephalocaudal direction caused the dogs to adopt a strategy of response which would keep them from falling down during the period of imposed motion or perturbation.2. A Fourier analysis of the response variables provided a quantitative measure of the distortion in the induced movement at the various hind leg joints and in the motion of the body. Certain aspects of the distortion could be accounted for by recognized random events such as drift and panting. The remainder of the distortion was task related and therefore provided evidence that the dog's postural control system behaved essentially as a non-linear system.3. The motion of the body was less distorted than the motion at the joints. The frequency response of the body motion resembled that of a second order linear system, but the amplitude of the body motion did not vary in constant proportion with changes in the amplitude of the input. Further, the phase relation between body motion and platform motion was not constant when the amplitude of the input was changed. Therefore, it was concluded that the control of the body position was probably non-linearly related to the input disturbance but that the low pass filter characteristics tended to minimize the appearance of distortion in that system output.4. Control of the position of the hind limb is related to the control of the torque generated at the hind limb joints. To the extent that joint angle and change in joint angle are related to the torque at a joint, the distortion of the motion at the joints clearly demonstrates that control of the hind limb during this postural task was non-linearly related to the sinusoidal input.II-2 J. M. BROOKHART AND R. E. TALBOTT 5. The uniformity of the response parameters, as assessed from the Fourier coefficients, indicated that all of the tested dogs adopted the same or nearly the same strategy for solving the problem of adjusting their postural control in response to the perturbation. Therefore, a reasonable hypothesis for future testing is that the central programme which generates this particular postural response will be structured similarly from one dog to the next.

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Section: Discussionmentioning

confidence: 99%

The postural response of normal dogs to sinusoidal displacement

Brookhart¹,

Talbott²

1974

The Journal of Physiology

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“…The process of transforming a physical stretch into a train of impulses in the afferent fiber was considered to take place as a set of steps, each of which could be modeled with a transfer function (the input-output equation) (Loewenstein et al, 1963; Terzuolo and Washizu, 1962; Washizu and Terzuolo, 1966). The same principles were subsequently applied to the mammalian stretch receptor (Poppele and Terzuolo, 1968; Roberts et al, 1971). Stretching the muscle (by other muscles or external forces) activates the receptor which, in turn, excites the muscle that contains it, causing the muscle to shorten, effectively counteracting the stretch to maintain stability.…”

Section: Movement—reflex and Volitionmentioning

confidence: 99%

Movement: How the Brain Communicates with the World

Schwartz

2016

Cell

107

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Voluntary movement is a result of signals transmitted through a communication channel that links the internal world in our minds to the physical world around us. Intention can be considered the desire to effect change on our environment, and this is contained in the signals from the brain, passed through the nervous system to converge on muscles that generate displacements and forces on our surroundings. The resulting changes in the world act to generate sensations that feed back to the nervous system, closing the control loop. This Perspective discusses the experimental and theoretical underpinnings of current models of movement generation and the way they are modulated by external information. Movement systems embody intentionality and prediction, two factors that are propelling a revolution in engineering. Development of movement models that include the complexities of the external world may allow a better understanding of the neuronal populations regulating these processes, as well as the development of solutions for autonomous vehicles and robots, and neural prostheses for those who are motor impaired.

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“…Control models of the stretch reflex developed by Poppele & Terzuolo (1968) and Roberts, Rosenthal & Terzuolo (1971) most potent feed-back from the periphery usually comes from muscle length detectors, the spindle endings, rather than force detectors, the tendon organs (see later). Thus in order to be useful in analyses of stability, a description of the forward pathway should really include the transduction of muscle force into load displacement.…”

Section: Open-loop Responsesmentioning

confidence: 99%

“…The isometric frequency-response curves obtained with modulated electrical stimulation in our subjects showed similar low-pass characteristics to those described ELECTRICALLY EVOKED TREMOR for muscles in cats (Rosenthal et al 1970;Mannard & Stein, 1973) and marginally higher roll-off frequencies than those in a comparable previous study in man (Aaron & Stein, 1976). Control models of the stretch reflex developed by Poppele & Terzuolo (1968) and Roberts, Rosenthal & Terzuolo (1971) Fig. 7.…”

Section: Open-loop Responsesmentioning

confidence: 99%

Instability in human forearm movements studied with feed‐back‐controlled electrical stimulation of muscles.

Jacks

Procházka

Trend

1988

The Journal of Physiology

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SUMMARY1. Amplitude-modulated electrical stimulation was applied to the elbow flexors and extensors to produce movements of the forearm in normal subjects. The parameters of the modulating (command) signal were set in isometric trials so as to produce equal and opposite background torques, and equal and supportive torque modulations.2. Bode plots relating forearm movement to command signal (modulating) frequency showed the muscle-load to have a low-pass characteristic similar to that previously described in the cat, and a slightly larger bandwidth than described previously in man.3. The transduced forearm signals were fed back to provide the command signal to the stimulators via a filter whlich mimicked the transfer function of muscle spindle primary endings. In effect this replaced the neural part of the reflex arc with an accessible model, but left the muscle-load effector intact.4. All six subjects developed forearm oscillations (tremor) when the loop gain exceeded a threshold value. The mean tremor frequency at onset was 4-4 Hz, which was similar to that of the equivalent vibration-evoked tremor (previous paper, Prochazka & Trend, 1988).5. With the linear spindle model, oscillations tended to grow rapidly in amplitude, and the stimuli became painful. The inclusion of a logarithmic limiting element resulted in stable oscillations, without significant alterations in frequency. This allowed us to study the effect on tremor of including analog delays in the loop, mimicking those associated with peripheral nerve transmission and central reflexes. In one subject, loop delays of 0, 20, 40 and 100 ms resulted in tremor at 4 0, 3'6, 3 0 and 2-1 Hz respectively, as quantified by spectral analysis.6. By considering separately the phase contributions of the different elements of the reflex arc, including delays, it became clear that muscle-load properties were important in setting the upper limit of tremor frequencies which could conceivably be supported by reflexes.7. The results support the conclusion of the related vibration study (Prochazka & Trend, 1988), that for moderate levels of background co-contraction, the contribution * Present address:

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A control model of stretch reflex.

Cited by 27 publications

References 0 publications

The postural response of normal dogs to sinusoidal displacement

The postural response of normal dogs to sinusoidal displacement

Movement: How the Brain Communicates with the World

Instability in human forearm movements studied with feed‐back‐controlled electrical stimulation of muscles.

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