Dynamic response of human muscle spindle afferents to stretch

1990 ◽  
Vol 63 (6) ◽  
pp. 1297-1306 ◽  
Author(s):  
B. B. Edin ◽  
A. B. Vallbo
Keyword(s):  
Dynamic Response ◽  
Muscle Spindle ◽  
Human Subjects ◽  
Muscle Afferents ◽  
Human Muscle ◽  
Golgi Tendon Organ ◽  
Muscle Spindle Afferents ◽  
Partial Data ◽  
Extensor Muscles ◽  
Tendon Organ

1. One hundred and twenty-four muscle afferents from the finger extensor muscles were recorded from the radial nerve in human subjects. 2. The afferents were provisionally classified as muscle spindle primary (78/124) and secondary afferents (25/124), and Golgi tendon organ afferents (21/124), on the basis of their response to 1) maximal twitch contractions, 2) 20- and 50-Hz sinusoids superimposed on ramp-and-hold stretches, 3) stretch sensitization, and 4) isometric contractions and sudden relaxations. 3. Ramp-and-hold stretches at two velocities, 10 and 50 degrees/s, were applied to the appropriate metacarpophalangeal (MCP) joint while the parent muscle remained relaxed. For each unit three discrete parameters were assessed: the presence or absence of 1) an initial burst at the commencement of the ramp stretch, 2) a deceleration response at the beginning of the hold phase, and 3) a prompt silencing at muscle shortening. In addition, two kinds of dynamic indexes were calculated for 79 of the muscle spindle afferents. 4. Most spindle afferents responded readily to stretch, whereas the Golgi tendon organ afferents produced very poor stretch responses. All of them lacked a static response, whereas the dynamic response, when present at all, consisted of only a few impulses. 5. The dynamic index was higher for spindle primaries than for secondaries, and this difference was statistically significant although the distribution was unimodal for spindle afferents as a group. Hence, this parameter was a poor discriminator. 6. Initial bursts, deceleration responses, and silences during imposed shortening were more common in spindle primaries than in secondaries. The differences were significant in all these respects. 7. The three discrete parameters were statistically pairwise independent for the spindle afferents, justifying the combination of the three into a useful battery for discrimination between primary and secondary spindle afferents and the use of this battery as a partial data base for a probability approach towards a solid classification of human muscle afferents.

Classification of human muscle stretch receptor afferents: a Bayesian approach

1990 ◽  
Vol 63 (6) ◽  
pp. 1314-1322 ◽  
Author(s):  
B. B. Edin ◽  
A. B. Vallbo
Keyword(s):  
Muscle Spindle ◽  
Small Amplitude ◽  
Discharge Rate ◽  
Muscle Afferents ◽  
Human Muscle ◽  
Golgi Tendon Organ ◽  
Bayesian Decision ◽  
Prior Probabilities ◽  
Tendon Organ

1. A sample of 124 human muscle afferents originating from the finger extensor muscles were recorded from the radial nerve in the upper arm. A method is described to formalize the classification of units in muscle spindle primary and secondary afferents and Golgi tendon organ afferents on the basis of a few, nonrigorous assumptions. The classification was based on experimental data that largely have been described in a series of previous papers, although some additional data were collected in the present study. 2. The units were subjected to five tests providing identification data: twitch contraction test, ramp-and-hold stretch, small-amplitude sinusoidal stretches superimposed on ramp stretch, stretch sensitization, and isometric contraction/relaxation. From these five tests the following eight response features were extracted: response to maximal isometric twitch contractions, type of stretch sensitization, correlation between discharge rate and contractile force, response to sudden isometric relaxation, presence or absence of an initial burst, deceleration response, prompt silencing at slow muscle shortening, and driving by small-amplitude sinusoidal stretches. 3. A Bayesian decision procedure was adopted to classify the units on the basis of the eight discriminators. As a first step, units were provisionally classified into muscle spindle primary and secondary afferents, and Golgi tendon organ afferents, by intuitively weighting their responses to the identification tests. Prior probabilities were estimated on the basis of the provisional classification. The eight response features were analyzed and tabulated for all afferents, and the likelihood functions of the tests were directly calculated on the basis of these data.(ABSTRACT TRUNCATED AT 250 WORDS)

Muscle afferent responses to isometric contractions and relaxations in humans

1990 ◽  
Vol 63 (6) ◽  
pp. 1307-1313 ◽  
Author(s):  
B. B. Edin ◽  
A. B. Vallbo
Keyword(s):  
Muscle Spindle ◽  
Isometric Contraction ◽  
Discharge Rate ◽  
Golgi Tendon Organ ◽  
Muscle Spindle Afferents ◽  
Golgi Tendon Organs ◽  
Relaxation Phase ◽  
Isometric Twitch ◽  
The Individual ◽  
Tendon Organ

1. One hundred and two single afferents from the finger extensor muscles of humans were studied with the microneurography technique. 2. The afferents were provisionally classified as primary muscle spindle afferents (62/102), secondary spindle afferents (22), and Golgi tendon organ afferents (18) on the basis of their responses to four tests: 1) ramp-and-hold stretch, 2) 20- and 50-Hz small-amplitude sinusoidal stretch superimposed on ramp-and-hold stretch, 3) maximal isometric twitch contraction, and 4) stretch sensitization. 3. The response profiles of the three unit types were analyzed during slowly rising isometric contraction terminating with an abrupt relaxation. About 75% (61/84) of all muscle spindle afferents increased their discharge during isometric contraction, whereas the discharge was reduced for the remaining afferents. All Golgi tendon organs increased their discharge during the contraction. 4. The level of extrafusal contraction at which a spindle afferent increased its discharge rate often varied from trial to trial, speaking against a fixed fusimotor recruitment level of the individual spindle ending. 5. In 70% of the spindle afferents, a distinct burst of impulses appeared when the subject rapidly relaxed after the isometric contraction. The burst was more common and usually much more prominent with primary than secondary afferents, often reaching instantaneous discharge rates well above 100 Hz. 6. Whereas all Golgi tendon organ afferents displayed an increased discharge during the contraction phase, only one of them exhibited a rate acceleration close to the relaxation phase. However, this response could clearly be identified as being of different nature than the spindle bursts.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Goal-dependent tuning of muscle spindle receptors during movement preparation

2020 ◽  
Author(s):  
Stylianos Papaioannou ◽  
Michael Dimitriou
Keyword(s):  
Muscle Spindle ◽  
Muscle Afferents ◽  
Human Muscle ◽  
Neural Mechanisms ◽  
Voluntary Movements ◽  
Movement Preparation ◽  
Manual Task ◽  
Spindle Bearing ◽  
Preparatory Activity ◽  
Arm Muscles

AbstractVoluntary movements are believed to be advantageously prepared before they are executed, but the neural mechanisms at work have been unclear. For example, there are no overt changes in skeletal muscle activity during movement preparation. Here, using a delayed-reach manual task, we demonstrate a decrease in the firing rate of human muscle afferents (primary spindles) when preparing stretch rather than shortening of the spindle-bearing muscle. This goal-dependent modulation of proprioceptors begun early after target onset but was markedly stronger at the latter parts of the preparatory period. In two additional experiments, whole-arm perturbations during reach preparation revealed a congruent modulation of stretch reflex gains of shoulder and upper arm muscles. Our study shows that movement preparation can involve sensory elements of the peripheral nervous system. We suggest that central preparatory activity can also reflect sensory control, and preparatory tuning of muscle spindle mechanoreceptors is a component of planned reaching movements.

scholarly journals Molecular development of muscle spindle and Golgi tendon organ sensory afferents revealed by single proprioceptor transcriptome analysis

2020 ◽  
Author(s):  
Katherine M. Oliver ◽  
Danny M. Florez-Paz ◽  
Tudor C. Badea ◽  
George Z. Mentis ◽  
Vilas Menon ◽  
...  
Keyword(s):  
Muscle Spindle ◽  
Developmental Stages ◽  
Motor Behavior ◽  
Molecular Signature ◽  
Golgi Tendon Organ ◽  
Sensory Afferents ◽  
Electrophysiological Recordings ◽  
Muscle Afferent ◽  
Tendon Organ

AbstractAnatomical and physiological analyses have long revealed differences between proprioceptive groups Ia, II, and Ib sensory neurons, yet the molecular correlates of these three muscle afferent subtypes remain unknown. We performed single cell RNA sequencing of genetically identified adult proprioceptors and, using unbiased bioinformatics approaches, detected five molecularly distinct neuronal clusters. Validation of cluster-specific transcripts in dorsal root ganglia (DRG) and skeletal muscle provides evidence these clusters correspond to functionally distinct muscle spindle (MS) or Golgi tendon organ (GTO) afferent proprioceptors. Remarkably, while we uncovered just one type of GTO afferents, four of the five clusters represent MS afferents, thus demonstrating a previously unappreciated diversity among these muscle proprioceptors. In vitro electrophysiological recordings reveal just two broadly distinct proprioceptor types, and suggest that the refinement of functional subtype diversity may occur along multiple axes of maturation. Lineage analysis between proprioceptor transcriptomes at different developmental stages show little or no correlation for transcripts that define adult MS or GTO afferents, supporting the idea that proprioceptor subtype identity emerges late in development. Together, our data provide the first comprehensive molecular signature for groups Ia and II MS afferents and group Ib GTO afferents, and offer new strategies for genetic interrogation of the role of these individual proprioceptor subtypes in regulating voluntary motor behavior.

Component of muscle spindle discharge related to arterial pulse

1981 ◽  
Vol 46 (4) ◽  
pp. 788-796 ◽  
Author(s):  
B. McKeon ◽  
D. Burke
Keyword(s):  
Blood Flow ◽  
Muscle Spindle ◽  
Time Course ◽  
Discharge Rate ◽  
Human Subjects ◽  
Arterial Blood Flow ◽  
Arterial Pulse ◽  
Muscle Spindle Afferents ◽  
Arterial Blood ◽  
Doppler Flowmeter

1. In human subjects microelectrode recordings were made from 25 muscle spindle afferents from the pretibial muscles. 2. The spike discharges of three endings were locked in time to the arterial pulse. With 17 of the remaining endings, there was a significant pulse-related modulation of discharge rate. For these 20 endings the latency to the onset of the pulse-related influence was 200-310 ms. 3. The time course of the modulation of discharge rate was similar to that of arterial blood flow, as estimated using a Doppler flowmeter. With four endings occlusion of blood flow using a sphygmomanometer cuff reduced any modulation. 4. For five endings the contribution by the arterial modulation to the variance of discharge of the ending was 3-54%. For the population of endings there was no significant relationship between the depth of modulation and coefficient of variation. 5. It is concluded that the arterial pulse can be significant contributor to the variability of muscle spindle discharge. The pulsatile effects seen in the responses of single afferents are unlikely to be eliminated in the summed activity forming the population response. This could constitute a limitation of the information capacity of the population of muscle spindle afferents.

Sign in / Sign up

Export Citation Format

Share Document