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- Edin, Benoni B, et al.
(författare)
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Stretch sensitization of human muscle spindles.
- 1988
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Ingår i: Journal of Physiology. - 0022-3751 .- 1469-7793. ; 400, s. 101-11
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Tidskriftsartikel (refereegranskat)abstract
- 1. Sixty-seven afferents from the finger extensor muscles were consecutively recorded by microneurography. 2. The units were classified as primary or secondary muscle spindle afferents or Golgi tendon organ afferents on the basis of their responses to ramp-and-hold stretches, sinusoidals superimposed on ramp-and-hold stretches, maximal twitch contractions and isometric contractions and relaxations. 3. The muscle was repeatedly stretched and then either kept short or long for a few seconds followed by a slow ramp stretch. The responses of the muscle afferents to the slow stretch were compared under the two conditions. 4. Thirty out of thirty-eight units classified as primary spindle afferents and four out of eleven units classified as secondary afferents showed an enhanced response to the slow ramp when the muscle had been kept short compared to the response when the muscle had been kept long. 5. None of the eighteen Golgi tendon organ afferents showed any difference in this respect. 6. It is concluded that stretch sensitization does occur in human muscle spindles and, when present, constitutes firm evidence of the afferent originating from a muscle spindle rather than a Golgi tendon organ. In addition, due to differences in the response characteristics of primaries and secondaries, the test may aid in separating muscle spindle primary afferents from secondary afferents.
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| 2. |
- Edin, Benoni B, et al.
(författare)
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Twitch contraction for identification of human muscle afferents.
- 1987
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772 .- 1365-201X. ; 131:1, s. 129-138
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Tidskriftsartikel (refereegranskat)abstract
- A classical test to differentiate between Golgi tendon organs and muscle spindles is the twitch contraction elicited by electrical stimulation. The possibility of producing maximal twitches in the finger extensor muscles using surface stimulation over the muscle belly was investigated as well as the feasibility of the test in microneurography experiments. Electrical stimuli were applied either over the muscle in the forearm or the radial nerve in the upper arm, while the resulting torque output at single metacarpophalangeal joints was measured. The relationship between current intensity and maximal contraction force was determined and stimulus response plots were constructed over a large range of current intensities. Stimulation of the radial nerve always yielded plots with a steep and monotonous rising limb up to a plateau. It was concluded that the plateau represented maximal twitch contractions. With transcutaneous stimulation over the muscle belly, the stimulus response plots were usually more complex. However, this could be explained by force transmission through the intertendinous connections on the dorsum of the hand and by antagonist activation. It was concluded that maximal twitch contractions can readily be elicited in the human extensor digitorum muscle with nonpainful transcutaneous electrical stimulations. Moreover, maximal twitches are compatible with single unit recording from muscle afferents in microneurography experiments.
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| 3. |
- Edin, Benoni B., 1956-
(författare)
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Classification of muscle stretch receptor afferents in humans
- 1988
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The response patterns of human stretch receptors in the finger extensor muscles of the forearm were studied using the microneurography technique. Single-unit recordings were obtained from one-hundred and twenty-four afferents. A procedure was developed to classify the units in muscle spindle primary afferents, secondary afferents, and Golgi tendong organ afferents. The procedure allows an objective and reproducible classification on the basis of the afferents’ responses to a series of tests which individually are non-conclusive.It was demonstrated that maximal twitch contractions can be elicited in the finger extensor muscles of the forearm, without causing undue discomfort to the subjects, or hazarding the single-unit recording. The response of the units to this test allowed, in most cases but not always, a separation in muscle spindle and tendon organ afferents. Thus the test was not adequate for an unequivocal classification.Three discrete response parameters were extracted from ramp-and-hold stretches, viz. the presence or absence of an initial burst and a deceleration response, and prompt silencing at slow muscle shortening. The distributions of the parameters were significantly different among the three unit types. These parameters which were pair-wise independent constituted a set of considerable discriminative power. It was shown that human muscle spindles have about the same static position sensitivity to fractional muscle stretch as previously found in animals.Stretch sensitization was demonstrated by rapid, repeated stretches of the muscle which enhanced the réponse to subsequent slow stretches of muscle spindles. Sensitization was different with primary and secondary muscle spindle afferents whereas Golgi tendon organ afferents never displayed stretch sensitization.One-to-one driving with small-amplitude sinusoidal stretches superimposed on ramp-and- hold stretches was almost exclusively seen with primary muscle spindle afferents, whereas secondaries seldom and tendon organ afferents never displayed driving.The afferent responses during slowly increasing isometric contractions and rapid relaxations were analysed. An increased discharge rate on relaxation was common among spindle afferents whereas it was never seen in tendon organs afferents. Two separate groups of spindles afferents were found with regard to fusimotor recruitment. The largest group was recruited at rather low and variable contractile forces whereas the smaller group was not recruited at all.The proportions of the three unit types, spindle primary, spindle secondary, and Golgi tendon organ afferents were estimated from a preliminary classification and the distribution of the eight response features were analyzed for each class of afferents. On the basis of these estimates and the response pattern of the individual unit Bayes’ theorem was used to calculate the probabilities that the unit was a spindle primary, a spindle secondary, or a tendon organ afferent. Estimates indicate that about 19 out of 20 muscle afferents are correctly classified when all eight features are analyzed.
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| 4. |
- Edin, Benoni B, et al.
(författare)
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Single unit retrieval in microneurography : a microprocessor-based device controlled by an operator.
- 1988
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Ingår i: Journal of Neuroscience Methods. - 0165-0270 .- 1872-678X. ; 24:2, s. 137-144
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Tidskriftsartikel (refereegranskat)abstract
- A microprocessor-based device was constructed to retrieve single unit activity from nerve recordings contaminated by other units and EMG activity. The microneurographic signal is sampled at 10 kHz and an algorithm applied to identify impulses from a single nerve fibre. On line, a TTL pulse is delivered when an event, i.e. a provisional nerve impulse, is selected. The wave form and clock time of events are stored. Moreover, the latest selected event and the actual selection criteria are continuously displayed on a standard oscilloscope. Off line, the wave form and clock time of events as well as an instantaneous frequency plot can be displayed on the oscilloscope. The final selection of events is done with a combination of a second algorithm, which essentially is a wave form comparator, and a manual check. The device is controlled either by hardware, with knobs on the front panel, or by software through a data bus connected to a microcomputer. Clock times and wave forms of the events, which are stored in the microprocessor memory, may also be presented on the data bus for later off-line analysis and coordination with other related signals collected during the experiment, e.g. transducer and electromyography records, whether these were stored on analog or digital tape or computer disc. Compared to other available techniques, the device has a superior discriminative power when electromyographic artefacts are present.
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