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IEEE Transactions on Neural Systems and... Oct 2009In this study, we explored the feasibility of estimating muscle length in passive conditions by interpreting nerve responses from muscle spindle afferents recorded with...
In this study, we explored the feasibility of estimating muscle length in passive conditions by interpreting nerve responses from muscle spindle afferents recorded with thin-film longitudinal intrafascicular electrodes. Afferent muscle spindle response to passive stretch was recorded in ten acute rabbit experiments. A newly proposed first-order model of muscle spindle response to passive sinusoidal muscle stretch manages to capture the relationship between afferent neural firing rate and muscle length. We demonstrate that the model can be used to track random motion trajectories with bandwidth from 0.1 to 1 Hz over a range of 4 mm with a muscle length estimation error of 0.3 mm (1.4 degrees of joint angle). When estimation is performed using four-channel ENG there is a 50% reduction in estimate variation, compared to using single-channel recordings.
Topics: Action Potentials; Afferent Pathways; Animals; Electrodes, Implanted; Muscle Spindles; Muscle, Skeletal; Physical Stimulation; Rabbits
PubMed: 19775988
DOI: 10.1109/TNSRE.2009.2032286 -
The Journal of Pharmacology and... Sep 1965
Topics: Animals; Cats; Ganglionic Blockers; Muscle Spindles; Piperazines; Succinylcholine
PubMed: 4378996
DOI: No ID Found -
Journal of the Neurological Sciences Sep 1976Muscle spindles have been studied in 7 autopsied cases of Duchenne muscular dystrophy. The autopsies of 2 boys of similar age who died without known neuromuscular...
Muscle spindles have been studied in 7 autopsied cases of Duchenne muscular dystrophy. The autopsies of 2 boys of similar age who died without known neuromuscular disease were used as controls. The abnormalities found consisted of degenerative changes, atrophy and loss of intrafusal muscle fibres, thickening of the spindle capsule and widening of the periaxial space. In some very severely affected muscles there was evidence that spindles were destroyed in the course of the disease. Statistical comparison of these observations was made between the pathological and normal material. The muscle spindle innervation appeared normal in sectioned material. Teased preparations were not available for study.
Topics: Adolescent; Humans; Male; Muscle Spindles; Muscles; Muscular Dystrophies
PubMed: 133211
DOI: 10.1016/0022-510x(76)90077-0 -
Experimental Brain Research Sep 2022Heteronymous excitatory feedback from muscle spindles and inhibitory feedback from Golgi tendon organs and recurrent inhibitory circuits can influence motor...
Heteronymous excitatory feedback from muscle spindles and inhibitory feedback from Golgi tendon organs and recurrent inhibitory circuits can influence motor coordination. The functional role of inhibitory feedback is difficult to determine, because nerve stimulation, the primary method used in humans, cannot evoke inhibition without first activating the largest diameter muscle spindle axons. Here, we tested the hypothesis that quadriceps muscle stimulation could be used to examine heteronymous inhibition more selectively when compared to femoral nerve stimulation by comparing the effects of nerve and muscle stimulation onto ongoing soleus EMG held at 20% of maximal effort. Motor threshold and two higher femoral nerve and quadriceps stimulus intensities matched by twitch evoked torque magnitudes were examined. We found that significantly fewer participants exhibited excitation during quadriceps muscle stimulation when compared to nerve stimulation (14-29% vs. 64-71% of participants across stimulation intensities) and the magnitude of heteronymous excitation from muscle stimulation, when present, was much reduced compared to nerve stimulation. Muscle and nerve stimulation resulted in heteronymous inhibition that significantly increased with increasing stimulation evoked torque magnitudes. This study provides novel evidence that muscle stimulation may be used to more selectively examine inhibitory heteronymous feedback between muscles in the human lower limb when compared to nerve stimulation.
Topics: Electric Stimulation; Femoral Nerve; H-Reflex; Humans; Muscle Spindles; Muscle, Skeletal; Quadriceps Muscle
PubMed: 35881156
DOI: 10.1007/s00221-022-06422-7 -
Nagoya Journal of Medical Science Mar 1980
Review
Topics: Animals; Calcium; In Vitro Techniques; Ion Channels; Membrane Potentials; Models, Neurological; Muscle Spindles
PubMed: 6247658
DOI: No ID Found -
Medical Hypotheses Jul 2012Muscle spindles are increasingly recognized as playing a pivotal role in the cause of dystonia. This development and own laryngeal observations that support the idea of...
Muscle spindles are increasingly recognized as playing a pivotal role in the cause of dystonia. This development and own laryngeal observations that support the idea of causally "well-intentioned" stuttering motivated us to present the following hypothesis: stuttering events compensate for a sensory problem that arises when the abductor/adductor ratio of afferent impulse rates from the posterior cricoarytenoid and lateral cricoarytenoid muscle spindles is abnormally reduced and processed for the occasional determination of the vocal fold position. This hypothesis implies that functional and structural brain abnormalities might be interpreted as secondary compensatory reactions. Verification of this hypothesis (using technologies such as microneurography, dissection and muscle afferent block) is important because its confirmation could relink dystonia and stuttering research, change the direction of stuttering therapy and destigmatize stuttering radically.
Topics: Humans; Larynx; Models, Theoretical; Muscle Spindles; Stuttering
PubMed: 22537410
DOI: 10.1016/j.mehy.2012.03.025 -
Neuroscience Letters Aug 1980Single muscle spindle afferent and motor unit EMG spike trains have been recorded simultaneously during periods of spontaneous motor activity in triceps surae muscles of...
Single muscle spindle afferent and motor unit EMG spike trains have been recorded simultaneously during periods of spontaneous motor activity in triceps surae muscles of decerebrate cats. The approximate time course and magnitude of the motor unit contractions were extracted from the whole muscle force record by spike-triggered averaging, and the functional interactions between motor unit contractions and spindle discharge were assessed by cross-correlating their respective spike trains. We have found that both spindle group Ia and II afferents are responsive to the contractions of single motor units in the presence of spontaneous motor activity, being strongly coupled to the activity of some motor units and indifferent to the contractions of others. Moreover, the cross-correlation analysis revealed modulation of a single motor unit's discharge pattern by the input of a single Ia afferent.
Topics: Action Potentials; Animals; Cats; Decerebrate State; Muscle Spindles; Muscles; Periodicity
PubMed: 6221207
DOI: 10.1016/0304-3940(80)90255-4 -
The Journal of Physiology Apr 2002Previous reports showed that sympathetic stimulation affects the activity of muscle spindle afferents (MSAs). The aim of the present work is to study the characteristics...
Previous reports showed that sympathetic stimulation affects the activity of muscle spindle afferents (MSAs). The aim of the present work is to study the characteristics of sympathetic modulation of MSA response to stretch: (i) on the dynamic and static components of the stretch response, and (ii) on group Ia and II MSAs to evaluate potentially different effects. In anaesthetised rabbits, the peripheral stump of the cervical sympathetic nerve (CSN) was stimulated at 10 impulses s(-1) for 45-90 s. The responses of single MSAs to trapezoidal displacement of the mandible were recorded from the mesencephalic trigeminal nucleus. The following characteristic parameters were determined from averaged trapezoidal responses: initial frequency (IF), peak frequency at the end of the ramp (PF), and static index (SI). From these, other parameters were derived: dynamic index (DI = PF - SI), dynamic difference (DD = PF - IF) and static difference (SD = SI - IF). The effects of CSN stimulation were also evaluated during changes in the state of intrafusal muscle fibre contraction induced by succinylcholine and curare. In a population of 124 MSAs, 106 units (85.4 %) were affected by sympathetic stimulation. In general, while changes in resting discharge varied among different units (Ia vs. II) and experimental conditions (curarised vs. non-curarised), ranging from enhancement to strong depression of firing, the amplitude of the response to muscle stretches consistently decreased. This was confirmed and detailed in a quantitative analysis performed on 49 muscle spindle afferents. In both the non-curarised (23 units) and curarised (26 units) condition, stimulation of the CSN reduced the response amplitude in terms of DD and SD, but hardly affected DI. The effects were equally present in both Ia and II units; they were shown to be independent from gamma drive and intrafusal muscle tone and not secondary to muscle hypoxia. Sympathetic action on the resting discharge (IF) was less consistent. In the non-curarised condition, IF decreased in most Ia units, while in II units decreases and increases occurred equally often. In the curarised condition, IF in group II units mostly increased. The results have important functional implications on the control of motor function in a state of 'high' sympathetic activity, like excessive stress, as well as in certain pathological conditions such as sympathetically maintained pain.
Topics: Animals; Curare; Electric Stimulation; Jaw; Masseter Muscle; Muscle Spindles; Neuromuscular Depolarizing Agents; Neuromuscular Nondepolarizing Agents; Neurons, Afferent; Rabbits; Succinylcholine; Sympathetic Nervous System
PubMed: 11927683
DOI: 10.1113/jphysiol.2001.014316 -
Neuroscience Research Jul 1996Intraaxonal recordings of 33 spindle afferents from the inspiratory (n = 8) and expiratory (n = 25) intercostal muscles in the lower thoracic segment (T9-11), were made...
Intraaxonal recordings of 33 spindle afferents from the inspiratory (n = 8) and expiratory (n = 25) intercostal muscles in the lower thoracic segment (T9-11), were made during spontaneous breathing in the anesthetized cat. All of them showed respiration-related activity. However, only three spindle afferents (one from the inspiratory and two from the expiratory intercostal muscles) showed higher firing frequency during the active contraction phase of the receptor-bearing muscle. The remaining 30 spindle afferents (seven from the inspiratory and 23 from the expiratory muscles) showed the maximum firing discharge during the passive stretch phase of the parent muscles. On the other hand, in the middle thoracic segments (T6-7), five of six spindle afferents from the inspiratory muscles and four of nine spindle afferents from the expiratory muscles showed maximum firing rate during parent muscle contraction in agreement with previous study. These results suggest that the spindle activity in the lower thoracic segments is dominated by muscle length changes, whereas that in the middle thoracic segments is largely via the fusimotor pathway.
Topics: Animals; Cats; Electrophysiology; Intercostal Muscles; Muscle Contraction; Muscle Spindles; Neurons, Afferent; Respiration; Thorax
PubMed: 8856726
DOI: 10.1016/0168-0102(96)01052-8 -
Archives of Oral Biology 1987Muscle-spindle density and size, in relation to extrafusal fibre-type, were examined in different portions of the masseter of six normal males by enzyme histochemistry....
Muscle-spindle density and size, in relation to extrafusal fibre-type, were examined in different portions of the masseter of six normal males by enzyme histochemistry. A direct relationship between spindle density, intrafusal fibre density and spindle size, and proportion of type I muscle fibres was found in the deep portion. Out of 410 muscle spindles in random samplings, 74 per cent were in the deep portion which is predominantly composed of type I fibres. Spindle density was three times greater than in the other portions, and spindles were commonly clustered, sometimes sharing capsule tissue. The deep masseter spindles were distinctive; they had the largest diameter and the most intrafusal fibres, the fibre density being four times greater than in other portions. Eleven per cent of the spindles, mainly in the deep portion, contained an unusually high number of intrafusal fibres (15 or more fibres). The findings imply that individual portions of the masseter have specialized functions. An especially powerful proprioceptive reflex mechanism is suggested for the deep portion. Thus, the human masseter may be part of an intricate, evolutionarily advanced, motor system also connected with speech.
Topics: Adolescent; Adult; Child; Humans; Male; Masseter Muscle; Masticatory Muscles; Muscle Spindles
PubMed: 2960303
DOI: 10.1016/s0003-9969(87)80009-2