‘Long-loop’ reflexes can be obtained in spinal monkeys

Tracey, David J.; Walmsley, Bruce; Brinkman, J.

doi:10.1016/0304-3940(80)90213-x

Cited by 76 publications

(28 citation statements)

References 14 publications

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“…It may be speculated that the low long-latency EMG activity recorded during those cycles resulted mainly from some spinal neuronal reflex mechanisms set at a very low level by higher nervous centres. This suggestion is also supported by the above-cited experiment of Tracey et al (1980), who showed in cats that long-latency EMG responses to triceps surae stretching were still present, though attenuated, after cutting off the supraspinal influence by a spinal section at the Th 12 level.…”

Section: Electromyogramsupporting

confidence: 71%

The role of reflex activity in the regulation of muscle tone in rats

Ossowska

Lorenc‐Koci²,

Schulze³

et al. 1996

Experimental Physiology

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SUMMARYThe aim of the study was to assess the contribution of reflex activity to the regulation of muscle tone in rats. The experiment was carried out on young Wistar male and female rats. The hindfoot of a rat was flexed or extended at the ankle joint by 25 deg over 250 ms. The resistance of the foot to passive movements, as well as the electromyographic (EMG) activity in the gastrocnemius and the tibialis anterior muscles, were recorded simultaneously. During passive movements, reflex EMG activity developed simultaneously in both antagonistic muscles of the foot. Three components were distinguished: a short-latency EMG-A (within the first 0-20 ms of a movement), long-latency EMG-B (within 60-160 ms), and EMG-C (within 220-340 ms). When the amplitudes of EMG-B and EMG-C components of the gastocnemius muscle reflex response were greater than 50 ,uiV, a significant correlation was found between them and the maximum resistance of the hindfoot (MMGmaX) during flexion, whereas no such correlation was observed for the tibialis anterior muscle. No correlation was found when the amplitudes of the long-latency components of the gastrocnemius muscle were less than 50 #uV. Moreover, no correlation was observed between the EMG-A and the MMGmaX. The above results suggest that: (1) the muscle tone of the gastrocnemius muscle in rats seems to be regulated by long-latency (supraspinal) reflexes only when the level of EMG activity exceeds a critical threshold of ca 50 ,#V; (2) when the level of EMG activity is lower, a major role in the resistance of hindlimb muscles is played by some non-neuronal factors; and (3) the proposed animal model emphasizes new aspects of the reflex which may be useful in a search for basic mechanisms underlying changes in the muscle tone.

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Section: Electromyogramsupporting

confidence: 71%

The role of reflex activity in the regulation of muscle tone in rats

Ossowska

Lorenc‐Koci²,

Schulze³

et al. 1996

Experimental Physiology

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“…For instance, Ghez and Shinoda (1978) have shown in the spinal cat that these responses can involve the spinal pathway only. This result was claimed again by Tracey et al (1980) in the spinal monkey without any clear experimental evidence, whereas North and Tatton (1980) have emphasized the differences observed between species: "In the cat, motor cortical neuron (MCN) activity does not contribute to the generation of the 2nd EMG response peak, in support of the transection studies and in contrast to MCN activity related to the M2 response for monkey distal upper limb musculature." Lastly, from their recent studies on man, Hagbarth et al (1981) have claimed that the segmented EMG responses are almost solely due to segmented afferent burst rather than multiple central reflex pathways.…”

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confidence: 71%

Long loop and spinal reflexes in man during preparation for intended directional hand movements

Bonnet¹,

Requin²

1982

J. Neurosci.

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Advance information about the direction of a movement to be performed in a reaction time (RT) paradigm is known (I) to improve performance, (2) not to result in any related change in monosynaptic spinal reflexes triggered at the time of the response signal, and (3) to trigger related changes in the activity of a number of neurons in the motor cortex.The aim of this experiment was to compare the evolution of the early (Ml) and late (M2) responses to a muscular overload during the foreperiod of an RT task, according to advance information about movement direction.Four subjects were trained to perform wrist extension and flexion movements in order to point to a visual target on either the right or left of a display panel. One second before the movement signal, a warning signal indicated to the subject at which target he was to point. A hand position perturbation causing a stretch of the wrist flexors was triggered at various unpredictable times during this 1-set foreperiod.The analysis of the surface electromyogram recorded upon wrist flexors showed that the evolution of Ml and M2 response amplitudes differed during the foreperiod. Ml increased up to 600 msec after the warning and then decreased until the response signal, while M2 continued to increase during the whole foreperiod. There was no change, however, in this differential evolution in relation to advance information about movement direction.The results were interpreted as the combination of two preparatory processes: first, a general activation, expressed by M2 increase, which can be viewed as a pre-setting of motor structures for a rapid execution of the motor program, and second, an inhibition of spindle afferent action upon spinal motor structures, expressed by the decrease of Ml response before movement execution, which can be viewed as a mechanism for protecting the motoneurons about to be activated from peripheral control pathways. Lastly, no specific presetting of the motor structures involved in Ml and M2 electromyographic responses according to the movement direction was found.An examination of spinal excitability changes in human subjects by soliciting the monosynaptic reflex either by electrical stimulation of the nerve or by tendinous tap has shown that, during the foreperiod of reaction time (RT) tasks, there is a selective modification in the excitability of the motoneurons controlling the muscle involved in the motor response (Requin, 1969;Gerilovski and Tsekov, 1971;Requin and Paillard, 1971). However, this pre-setting was expressed in a relative depression of reflex pathway reactivity, the depth of which showed no change whether the muscle was acting as agonist or ' To whom correspondence should be addressed

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“…The net result of this arrangement as measured via surface electromyography would be a progressive reduction in gain-scaling. In fact, while it is well established that the long-latency response for the upper limb includes a cortical contribution from M1 (Matthews 1991), it has also been shown that phasic-activity within the long-latency epoch is present in decerebrate cats (Ghez and Shinoda 1978) and in both decerebrate (Miller and Brooks 1981) and spinalized monkeys (Tracey et al 1980). Taken together with these previous observations, our present results are consistent with the notion that long-latency activity is composed of at least two separate circuits which overlap in time (Pruszynski et al 2008b).…”

Section: Intermediate Gain-scaling In the Long-latency Epochmentioning

confidence: 99%

Temporal Evolution of “Automatic Gain-Scaling”

Pruszynski

Kurtzer²,

Lillicrap³

et al. 2009

Journal of Neurophysiology

146

140

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Pruszynski JA, Kurtzer I, Lillicrap TP, Scott SH. Temporal evolution of "automatic gain-scaling." J Neurophysiol 102: 992-1003, 2009. First published May 3, 2009 doi:10.1152/jn.00085.2009. The earliest neural response to a mechanical perturbation, the short-latency stretch response (R1: 20 -45 ms), is known to exhibit "automatic gain-scaling" whereby its magnitude is proportional to preperturbation muscle activity. Because gain-scaling likely reflects an intrinsic property of the motoneuron pool (via the size-recruitment principle), counteracting this property poses a fundamental challenge for the nervous system, which must ultimately counter the absolute change in load regardless of the initial muscle activity (i.e., show no gainscaling). Here we explore the temporal evolution of gain-scaling in a simple behavioral task where subjects stabilize their arm against different background loads and randomly occurring torque perturbations. We quantified gain-scaling in four elbow muscles (brachioradialis, biceps long, triceps lateral, triceps long) over the entire sequence of muscle activity following perturbation onset-the shortlatency response, long-latency response (R2: 50 -75 ms; R3: 75-105 ms), early voluntary corrections (120 -180 ms), and steady-state activity (750 -1250 ms). In agreement with previous observations, we found that the short-latency response demonstrated substantial gainscaling with a threefold increase in background load resulting in an approximately twofold increase in muscle activity for the same perturbation. Following the short-latency response, we found a rapid decrease in gain-scaling starting in the long-latency epoch (ϳ75-ms postperturbation) such that no significant gain-scaling was observed for the early voluntary corrections or steady-state activity. The rapid decrease in gain-scaling supports our recent suggestion that longlatency responses and voluntary control are inherently linked as part of an evolving sensorimotor control process through similar neural circuitry. I N T R O D U C T I O NA prominent and well-studied feature of the short-latency stretch response (R1: 20 -45 ms postperturbation) is "automatic gain-scaling" whereby the same muscle-stretch will elicit larger responses when preperturbation muscle activity is increased (Bedingham and Tatton 1984;Marsden et al. 1976;Matthews 1986;Stein et al. 1995;Verrier 1985). This modulation is generally attributed to the intrinsic organization of the motoneuron pool (Capaday and Stein 1987;Houk et al. 1970;Kernell and Hultborn 1990;Marsden et al. 1976;Matthews 1986;Slot and Sinkjaer 1994) where motor units are recruited in order of their force-generating capability and resilience to fatigue (Cope and Clark 1991; Henneman 1957), a phenomenon termed the size-recruitment principle. Although gainscaling may be a useful short-term strategy (Bedingham and Tatton 1984;Marsden et al. 1976;Matthews 1986), ultimately the steady-state response to an additional load must be independent of preperturbation muscle activity (i.e., not show gain-sc...

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‘Long-loop’ reflexes can be obtained in spinal monkeys

Cited by 76 publications

References 14 publications

The role of reflex activity in the regulation of muscle tone in rats

The role of reflex activity in the regulation of muscle tone in rats

Long loop and spinal reflexes in man during preparation for intended directional hand movements

Temporal Evolution of “Automatic Gain-Scaling”

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