Response of lumbar paraspinal muscles spindles is greater to spinal manipulative loading compared with slower loading under length control.

PubMed

Pickar, Joel G; Sung, Paul S; Kang, Yu-Ming; Ge, Weiqing

2007-01-01

Spinal manipulation (SM) is a form of manual therapy used clinically to treat patients with low back and neck pain. The most common form of this maneuver is characterized as a high-velocity (duration <150 ms), low-amplitude (segmental translation <2 mm, rotation <4 degrees , and applied force 220-889 N) impulse thrust (high-velocity, low-amplitude spinal manipulation [HVLA-SM]). Clinical skill in applying an HVLA-SM lies in the practitioner's ability to control the duration and magnitude of the load (ie, the rate of loading), the direction in which the load is applied, and the contact point at which the load is applied. Control over its mechanical delivery is presumably related to its clinical effects. Biomechanical changes evoked by an HVLA-SM are thought to have physiological consequences caused, at least in part, by changes in sensory signaling from paraspinal tissues. If activation of afferent pathways does contribute to the effects of an HVLA-SM, it seems reasonable to anticipate that neural discharge might increase or decrease in a nonlinear fashion as the thrust duration approaches a threshold value. We hypothesized that the relationship between the duration of an impulsive thrust to a vertebra and paraspinal muscle spindle discharge would be nonlinear with an inflection near the duration of an HVLA-SM delivered clinically (<150 ms). In addition, we anticipated that muscle spindle discharge would be more sensitive to larger amplitude thrusts. A neurophysiological study of spinal manipulation using the lumbar spine of a feline model. Impulse thrusts (duration: 12.5, 25, 50, 100, 200, and 400 ms; amplitude 1 or 2 mm posterior to anterior) were applied to the spinous process of the L6 vertebra of deeply anesthetized cats while recording single unit activity from dorsal root filaments of muscle spindle afferents innervating the lumbar paraspinal muscles. A feedback motor was used in displacement control mode to deliver the impulse thrusts. The motor's drive arm

Fusimotor control of spindle sensitivity regulates central and peripheral coding of joint angles.

PubMed

Lan, Ning; He, Xin

2012-01-01

Proprioceptive afferents from muscle spindles encode information about peripheral joint movements for the central nervous system (CNS). The sensitivity of muscle spindle is nonlinearly dependent on the activation of gamma (γ) motoneurons in the spinal cord that receives inputs from the motor cortex. How fusimotor control of spindle sensitivity affects proprioceptive coding of joint position is not clear. Furthermore, what information is carried in the fusimotor signal from the motor cortex to the muscle spindle is largely unknown. In this study, we addressed the issue of communication between the central and peripheral sensorimotor systems using a computational approach based on the virtual arm (VA) model. In simulation experiments within the operational range of joint movements, the gamma static commands (γ(s)) to the spindles of both mono-articular and bi-articular muscles were hypothesized (1) to remain constant, (2) to be modulated with joint angles linearly, and (3) to be modulated with joint angles nonlinearly. Simulation results revealed a nonlinear landscape of Ia afferent with respect to both γ(s) activation and joint angle. Among the three hypotheses, the constant and linear strategies did not yield Ia responses that matched the experimental data, and therefore, were rejected as plausible strategies of spindle sensitivity control. However, if γ(s) commands were quadratically modulated with joint angles, a robust linear relation between Ia afferents and joint angles could be obtained in both mono-articular and bi-articular muscles. With the quadratic strategy of spindle sensitivity control, γ(s) commands may serve as the CNS outputs that inform the periphery of central coding of joint angles. The results suggest that the information of joint angles may be communicated between the CNS and muscles via the descending γ(s) efferent and Ia afferent signals.

The muscle spindle as a feedback element in muscle control

NASA Technical Reports Server (NTRS)

Andrews, L. T.; Iannone, A. M.; Ewing, D. J.

1973-01-01

The muscle spindle, the feedback element in the myotatic (stretch) reflex, is a major contributor to muscular control. Therefore, an accurate description of behavior of the muscle spindle during active contraction of the muscle, as well as during passive stretch, is essential to the understanding of muscle control. Animal experiments were performed in order to obtain the data necessary to model the muscle spindle. Spectral density functions were used to identify a linear approximation of the two types of nerve endings from the spindle. A model reference adaptive control system was used on a hybrid computer to optimize the anatomically defined lumped parameter estimate of the spindle. The derived nonlinear model accurately predicts the behavior of the muscle spindle both during active discharge and during its silent period. This model is used to determine the mechanism employed to control muscle movement.

Phase correlated adequate afferent action potentials as a drive of human spinal oscillators.

PubMed

Schalow, G

1993-12-01

1. By recording, with 2 pairs of wire electrodes, single-fibre action potentials (APs) from lower sacral nerve roots of a brain-dead human and a patient with spinal cord lesion, impulse patterns of afferent APs and impulse trains of oscillatory firing motoneurons could be identified and correlated. 2. Two highly activated secondary muscle spindle afferents increased and decreased their activity at about 0.3 Hz. The duration of the doublet interspike interval of a secondary spindle afferent fibre showed no correlation to the oscillation period of the motoneuron. 3. A continuously oscillatory firing motoneuron innervating the external and sphincter showed more transient breaks with the reduction of the number of phase correlated APs from 2 spindle afferents, indicating a looser oscillation. A transient brake of a 157 msec period alpha 2-oscillation could be correlated to the shift of a interspike interval distribution peak from 150 to 180 msec of the adequate afferent input, which suggests a transient loss of the necessary phase relation. 4. Oscillatory firing alpha 2-motoneurons innervating the external bladder and anal sphincters fired independently according to their phase correlated APs from the urinary bladder stretch receptor and muscle spindle afferents respectively; the bladder motoneuron slightly inhibited the anal motoneuron. 5. Receptors of the afferents and innervation sites of oscillatory firing motoneurons could be located within the urinary tract and the anal canal.

TIME COURSE FOR THE DEVELOPMENT OF MUSCLE HISTORY IN LUMBAR PARASPINAL MUSCLE SPINDLES ARISING FROM CHANGES IN VERTEBRAL POSITION

PubMed Central

Pickar, Joel G.; Ge, Weiqing

2008-01-01

Background Context In neutral spinal postures with low loading moments the lumbar spine is not inherently stable. Small compromises in paraspinal muscle activity may affect lumbar spinal biomechanics. Proprioceptive feedback from muscle spindles is considered important for control of muscle activity. Because skeletal muscle and muscle spindles are thixotropic, their length history changes their physical properties. The present study explores a mechanism that can affect the responsiveness of paraspinal muscle spindles in the lumbar spine. Purpose This study had two aims: to extend our previous findings demonstrating the history dependent effects of vertebral position on the responsiveness of lumbar paraspinal muscle spindles; and to determine the time course for these effects. Based upon previous studies, if a crossbridge mechanism underlies these thixotropic effects, then the relationship between the magnitude of spindle discharge and the duration of the vertebral position will be one of exponential decay or growth. Study Design/Setting A neurophysiological study using the lumbar spine of a feline model. Methods The discharge from individual muscle spindles afferents innervating lumbar paraspinal muscles in response to the duration and direction of vertebral position were obtained from teased filaments in the L6 dorsal roots of 30 Nembutal-anesthetized cats. The L6 vertebra was controlled using a displacement-controlled feedback motor and was held in each of 3 different conditioning positions for durations of 0, 0.5, 1, 1.5, and 2 seconds. Two of the conditioning positions stretched or shortened the lumbar muscles relative to an intermediate conditioning position. Conditioning positions for all cats ranged from 0.9 – 2.0 mm dorsal and ventralward relative to the intermediate position. These magnitudes were determined based upon the displacement that loaded the L6 vertebra to 50–60% of the cat’s body weight. Conditioning was thought to simulate a motion

Thresholds of cortical activation of muscle spindles and α motoneurones of the baboon's hand

PubMed Central

Koeze, T. H.; Phillips, C. G.; Sheridan, J. D.

1968-01-01

1. Much current thinking about voluntary movement assumes that the segmental γ loops can function as a servomechanism operated by the brain. However, the α motoneurones of the baboon's hand receive a powerful monosynaptic (CM) projection from the precentral gyrus. If servo-driving from the same cortical area is to be possible, it must project independently to the fusimotor neurones and have sufficient power to increase the afferent signalling from the muscle spindles. The cortical thresholds for contraction of m. extensor digitorum communis and for acceleration of the discharges of its muscle spindles have therefore been compared. 2. Significant results in this context require that the spindles studied be coupled in parallel with the responding extrafusal muscle fibres. Many spindles were not unloaded by the submaximal contractions evoked by cortical stimulation, although all so tested were unloaded by maximal motor nerve twitches. Reasons are given for thinking that such apparent lack of parallel coupling is an artifact of complex intramuscular anatomy and limitation of shortening by `isometric' myography. 3. A brief burst of corticospinal volleys at 500/sec, which is specially effective in exciting α motoneurones over the CM projection, failed to excite spindle afferents at or below the threshold for a cortical `twitch'. 4. In a few epileptiform discharges, bursts of spindle acceleration occurred independently of the clonic contractions. A relatively direct and independent cortico-fusimotor (CF) projection may therefore exist. 5. Prolonged near-threshold stimulation at 50-100/sec, which allows time for temporal summation in the less direct projections (e.g. cortico-interneuronal, cortico-rubro-spinal) and does not cause frequency-potentiation at CM synapses, gives abundant evidence of independent α and fusimotor projections, whose actions hardly outlast the stimulation period. 6. Although independent CF projections would permit servo-driving in natural

Muscle afferent potential (`A-wave') in the surface electromyogram of a phasic stretch reflex in normal humans

PubMed Central

Clarke, Alex. M.; Michie, Patricia T.; Glue, Leonard C. T.

1972-01-01

The experiments reported in this paper tested the hypothesis that the afferent potential elicited by a tendon tap in an isometrically recorded phasic stretch reflex can be detected in the surface EMG of normal humans when appropriate techniques are used. These techniques involved (1) training the subjects to relax mentally and physically so that the EMG was silent before and immediately after the diphasic MAP which reflects a highly synchronous discharge of afferent impulses from low threshold muscle stretch receptors after a tendon tap, and (2) using a data retrieval computer to summate stimulus-locked potentials in the EMG over a series of 16 samples using taps of uniform peak force and duration on the Achilles tendon to elicit the tendon jerk in the calf muscles. A discrete, diphasic potential (`A-wave') was recorded from EMG electrodes placed on the surface of the skin over the medial gastrocnemius muscle. The `A-wave' afferent potential had the opposite polarity to the corresponding efferent MAP. Under control conditions of relaxation the `A-wave' had a latency after the onset of the tap of 2 msec, the peak to peak amplitude was of the order of 5 μV and the duration was in the range of 6 to 10 msec. Further experiments were conducted to show that the `A-wave' (1) was not an artefact of the instrumentation used, (2) had a threshold at low intensities of stimulation, and (3) could be reliably augmented by using a Jendrassik manoeuvre compared with the potential observed during control (relaxation) conditions. The results support the conclusion that the `A-wave' emanates from the pool of muscle spindles which discharges impulses along group Ia nerve fibres in response to the phasic stretch stimulus because the primary ending of the spindles is known to initiate the stretch reflex and the spindles can be sensitized by fusimotor impulses so that their threshold is lowered as a result of a Jendrassik manoeuvre. The finding has important implications for the

The decreased responsiveness of lumbar muscle spindles to a prior history of spinal muscle lengthening is graded with the magnitude of change in vertebral position

PubMed Central

Ge, Weiqing; Pickar, Joel G.

2013-01-01

In the lumbar spine, muscle spindle responsiveness is affected by the duration and direction of a lumbar vertebra’s positional history. The purpose of the present study was to determine the relationship between changes in the magnitude of a lumbar vertebra’s positional history and the responsiveness of lumbar muscle spindles to a subsequent vertebral position and subsequent vertebral movement. Neural activity from multifidus and longissimus muscle spindle afferents in deeply anesthetized cats was recorded while creating positional histories of the L6 vertebra. History was induced using a displacement-controlled feedback motor. It held the L6 vertebra for 4 seconds at an intermediate position (hold-intermediate at 0mm) and at 7 positions from 0.07 to 1.55mm more ventralward and dorsalward which lengthened (hold-long) and shortened (hold-short) the lumbar muscles. Following the conditioning hold positions, L6 was returned to the intermediate position. Muscle spindle discharge at this position and during a lengthening movement was compared between hold-intermediate and hold-short conditionings and between hold-intermediate and hold-short conditionings. We found that regardless of conditioning magnitude, the 7 shortening magnitudes similarly increased muscle spindle responsiveness to both vertebral position and movement. In contrast, the 7 lengthening magnitudes produced a graded decrease in responsiveness to both position and movement. The decrease to position became maximal following conditioning magnitudes of ~0.75 mm. The decrease to movement did not reach a maximum even with conditioning magnitudes of ~1.55 mm. The data suggest that the fidelity of proprioceptive information from muscle spindles in the low back is influenced by small changes in the previous length history of lumbar muscles. PMID:22721784

Cardinal features of involuntary force variability can arise from the closed-loop control of viscoelastic afferented muscles

PubMed Central

Laine, Christopher M.; Valero-Cuevas, Francisco J.

2018-01-01

Involuntary force variability below 15 Hz arises from, and is influenced by, many factors including descending neural drive, proprioceptive feedback, and mechanical properties of muscles and tendons. However, their potential interactions that give rise to the well-structured spectrum of involuntary force variability are not well understood due to a lack of experimental techniques. Here, we investigated the generation, modulation, and interactions among different sources of force variability using a physiologically-grounded closed-loop simulation of an afferented muscle model. The closed-loop simulation included a musculotendon model, muscle spindle, Golgi tendon organ (GTO), and a tracking controller which enabled target-guided force tracking. We demonstrate that closed-loop control of an afferented musculotendon suffices to replicate and explain surprisingly many cardinal features of involuntary force variability. Specifically, we present 1) a potential origin of low-frequency force variability associated with co-modulation of motor unit firing rates (i.e.,‘common drive’), 2) an in-depth characterization of how proprioceptive feedback pathways suffice to generate 5-12 Hz physiological tremor, and 3) evidence that modulation of those feedback pathways (i.e., presynaptic inhibition of Ia and Ib afferents, and spindle sensitivity via fusimotor drive) influence the full spectrum of force variability. These results highlight the previously underestimated importance of closed-loop neuromechanical interactions in explaining involuntary force variability during voluntary ‘isometric’ force control. Furthermore, these results provide the basis for a unifying theory that relates spinal circuitry to various manifestations of altered involuntary force variability in fatigue, aging and neurological disease. PMID:29309405

Cardinal features of involuntary force variability can arise from the closed-loop control of viscoelastic afferented muscles.

PubMed

Nagamori, Akira; Laine, Christopher M; Valero-Cuevas, Francisco J

2018-01-01

Involuntary force variability below 15 Hz arises from, and is influenced by, many factors including descending neural drive, proprioceptive feedback, and mechanical properties of muscles and tendons. However, their potential interactions that give rise to the well-structured spectrum of involuntary force variability are not well understood due to a lack of experimental techniques. Here, we investigated the generation, modulation, and interactions among different sources of force variability using a physiologically-grounded closed-loop simulation of an afferented muscle model. The closed-loop simulation included a musculotendon model, muscle spindle, Golgi tendon organ (GTO), and a tracking controller which enabled target-guided force tracking. We demonstrate that closed-loop control of an afferented musculotendon suffices to replicate and explain surprisingly many cardinal features of involuntary force variability. Specifically, we present 1) a potential origin of low-frequency force variability associated with co-modulation of motor unit firing rates (i.e.,'common drive'), 2) an in-depth characterization of how proprioceptive feedback pathways suffice to generate 5-12 Hz physiological tremor, and 3) evidence that modulation of those feedback pathways (i.e., presynaptic inhibition of Ia and Ib afferents, and spindle sensitivity via fusimotor drive) influence the full spectrum of force variability. These results highlight the previously underestimated importance of closed-loop neuromechanical interactions in explaining involuntary force variability during voluntary 'isometric' force control. Furthermore, these results provide the basis for a unifying theory that relates spinal circuitry to various manifestations of altered involuntary force variability in fatigue, aging and neurological disease.

An allometric analysis of the number of muscle spindles in mammalian skeletal muscles

PubMed Central

Banks, R W

2006-01-01

An allometric analysis of the number of muscle spindles in relation to muscle mass in mammalian (mouse, rat, guinea-pig, cat, human) skeletal muscles is presented. It is shown that the trend to increasing number as muscle mass increases follows an isometric (length) relationship between species, whereas within a species, at least for the only essentially complete sample (human), the number of spindles scales, on average, with the square root rather than the cube root of muscle mass. An attempt is made to reconcile these apparently discrepant relationships. Use of the widely accepted spindle density (number of spindles g−1 of muscle) as a measure of relative abundance of spindles in different muscles is shown to be grossly misleading. It is replaced with the residuals of the linear regression of ln spindle number against ln muscle mass. Significant differences in relative spindle abundance as measured by residuals were found between regional groups of muscles: the greatest abundance is in axial muscles, including those concerned with head position, whereas the least is in muscles of the shoulder girdle. No differences were found between large and small muscles operating in parallel, or between antigravity and non-antigravity muscles. For proximal vs. distal muscles, spindles were significantly less abundant in the hand than the arm, but there was no difference between the foot and the leg. PMID:16761976

The optimal neural strategy for a stable motor task requires a compromise between level of muscle cocontraction and synaptic gain of afferent feedback

PubMed Central

Dideriksen, Jakob L.; Negro, Francesco

2015-01-01

Increasing joint stiffness by cocontraction of antagonist muscles and compensatory reflexes are neural strategies to minimize the impact of unexpected perturbations on movement. Combining these strategies, however, may compromise steadiness, as elements of the afferent input to motor pools innervating antagonist muscles are inherently negatively correlated. Consequently, a high afferent gain and active contractions of both muscles may imply negatively correlated neural drives to the muscles and thus an unstable limb position. This hypothesis was systematically explored with a novel computational model of the peripheral nervous system and the mechanics of one limb. Two populations of motor neurons received synaptic input from descending drive, spinal interneurons, and afferent feedback. Muscle force, simulated based on motor unit activity, determined limb movement that gave rise to afferent feedback from muscle spindles and Golgi tendon organs. The results indicated that optimal steadiness was achieved with low synaptic gain of the afferent feedback. High afferent gains during cocontraction implied increased levels of common drive in the motor neuron outputs, which were negatively correlated across the two populations, constraining instability of the limb. Increasing the force acting on the joint and the afferent gain both effectively minimized the impact of an external perturbation, and suboptimal adjustment of the afferent gain could be compensated by muscle cocontraction. These observations show that selection of the strategy for a given contraction implies a compromise between steadiness and effectiveness of compensations to perturbations. This indicates that a task-dependent selection of neural strategy for steadiness is necessary when acting in different environments. PMID:26203102

In-series compliance of gastrocnemius muscle in cat step cycle: do spindles signal origin-to-insertion length?

PubMed Central

Elek, J; Prochazka, A; Hulliger, M; Vincent, S

1990-01-01

results suggested that the stiffness of the MG tendinous compartment was force related, and about double that of cat soleus muscle at any given force. Calculations indicated that though the stretch was small, the MG tendon would store and release enough strain energy per cycle to contribute significantly to the E3 phase of the step cycle. The discrepancies in spindle firing were generally quite subtle, so we reject the claim that extramysial stretch poses a serious difficulty for inferences about fusimotion from chronic spindle afferent recordings. PMID:2148952

Muscle spindle response at the onset of isometric voluntary contractions in man. Time difference between fusimotor and skeletomotor effects

PubMed Central

Vallbo, Å. B.

1971-01-01

1. Impulses in single muscle afferents were recorded from the median nerves of waking human subjects with percutaneously inserted tungsten needle electrodes. During isometric voluntary contractions, unitary discharges were analysed from muscle spindle endings in the wrist and finger flexor muscles and the electromyographic activity from these muscles was recorded simultaneously. 2. When the subject activated the muscle portion in which a spindle was located, the afferent discharge increased in spite of the mechanical unloading effects of the skeletomotor contraction indicating a concomitant fusimotor activation. This was valid for slowly rising contractions as well as small fast rising twitches. 3. The time of onset of spindle acceleration was determined in relation to the time of onset of the electromyographic activity for thirty-one units studied altogether in more than seven hundred contractions. It was found that spindle acceleration regularly occurred after the onset of the electromyographic activity. 4. There was a considerable variation from one test to the other, for the individual units, with regard to the exact time of onset of spindle acceleration, although spindle acceleration occurred mostly within 0·5 sec after the onset of the electromyographic activity in sustained contractions and within 0·1 sec in small fast rising twitches. It was not possible to assess to what extent this variation was accounted for by variations in the mechanical unloading effects of the skeletomotor contraction or variations in the timing of the fusimotor outflow. 5. For many units, spindle acceleration did not occur until 10-50 msec after the onset of the skeletomotor contraction. This time is of the same order of magnitude as the time difference in latency from the spinal cord to the recording points in the two systems, as estimated from reasonable assumptions. 6. It was concluded that the fusimotor system does not participate in the initiation of voluntary contractions in

Kinesthetic perception based on integration of motor imagery and afferent inputs from antagonistic muscles with tendon vibration.

PubMed

Shibata, E; Kaneko, F

2013-04-29

The perceptual integration of afferent inputs from two antagonistic muscles, or the perceptual integration of afferent input and motor imagery are related to the generation of a kinesthetic sensation. However, it has not been clarified how, or indeed whether, a kinesthetic perception would be generated by motor imagery if afferent inputs from two antagonistic muscles were simultaneously induced by tendon vibration. The purpose of this study was to investigate how a kinesthetic perception would be generated by motor imagery during co-vibration of the two antagonistic muscles at the same frequency. Healthy subjects participated in this experiment. Illusory movement was evoked by tendon vibration. Next, the subjects imaged wrist flexion movement simultaneously with tendon vibration. Wrist flexor and extensor muscles were vibrated according to 4 patterns such that the difference between the two vibration frequencies was zero. After each trial, the perceived movement sensations were quantified on the basis of the velocity and direction of the ipsilateral hand-tracking movements. When the difference in frequency applied to the wrist flexor and the extensor was 0Hz, no subjects perceived movements without motor imagery. However, during motor imagery, the flexion velocity of the perceived movement was higher than the flexion velocity without motor imagery. This study clarified that the afferent inputs from the muscle spindle interact with motor imagery, to evoke a kinesthetic perception, even when the difference in frequency applied to the wrist flexor and extensor was 0Hz. Furthermore, the kinesthetic perception resulting from integrations of vibration and motor imagery increased depending on the vibration frequency to the two antagonistic muscles. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Jaw muscles in older overdenture patients.

PubMed

Newton, James P; McManus, Frank C; Menhenick, Stephen

2004-03-01

To determine, using computer tomography (CT), whether the retention of a small number of teeth in the older adult used to support overdentures could affect the cross-sectional area (CSA) and X-ray density of two jaw closing muscles. Cross-sectional study of a group of older patients subdivided into dentate, edentulous and those wearing overdentures supported by two to five teeth. The sample consisted of 24 subjects aged 55-68 years. CSA and X-ray density of two jaw closing muscles, masseter and medial pterygoid were measured and evaluated using CT. There were no significant differences between left and right jaw muscles, but the CSA of the masseter muscles were significantly larger than the medial pterygoid muscles. The CSA of the masseter and medial pterygoid muscles was significantly smaller in edentulous subjects compared with dentate subjects but no significant difference was observed between subjects wearing overdentures and those with a natural dentition. No significant differences were observed with the X-ray density between different muscles or dental states. The retention of a small number of teeth in the older adult used to support overdentures appears to sustain the CSA of two jaw closing muscles and therefore could enhance these patients' masticatory ability compared with those who were edentulous.

Jaw-muscle fiber architecture in tufted capuchins favors generating relatively large muscle forces without compromising jaw gape.

PubMed

Taylor, Andrea B; Vinyard, Christopher J

2009-12-01

Tufted capuchins (sensu lato) are renowned for their dietary flexibility and capacity to exploit hard and tough objects. Cebus apella differs from other capuchins in displaying a suite of craniodental features that have been functionally and adaptively linked to their feeding behavior, particularly the generation and dissipation of relatively large jaw forces. We compared fiber architecture of the masseter and temporalis muscles between C. apella (n=12) and two "untufted" capuchins (C. capucinus, n=3; C. albifrons, n=5). These three species share broadly similar diets, but tufted capuchins occasionally exploit mechanically challenging tissues. We tested the hypothesis that tufted capuchins exhibit architectural properties of their jaw muscles that facilitate relatively large forces including relatively greater physiologic cross-sectional areas (PCSA), more pinnate fibers, and lower ratios of mass to tetanic tension (Mass/P(0)). Results show some evidence supporting these predictions, as C. apella has relatively greater superficial masseter and temporalis PCSAs, significantly so only for the temporalis following Bonferroni adjustment. Capuchins did not differ in pinnation angle or Mass/P(0). As an architectural trade-off between maximizing muscle force and muscle excursion/contraction velocity, we also tested the hypothesis that C. apella exhibits relatively shorter muscle fibers. Contrary to our prediction, there are no significant differences in relative fiber lengths between tufted and untufted capuchins. Therefore, we attribute the relatively greater PCSAs in tufted capuchins primarily to their larger muscle masses. These findings suggest that relatively large jaw-muscle PCSAs can be added to the suite of masticatory features that have been functionally linked to the exploitation of a more resistant diet by C. apella. By enlarging jaw-muscle mass to increase PCSA, rather than reducing fiber lengths and increasing pinnation, tufted capuchins appear to have

Muscle spindle autogenetic inhibition in the extraocular muscles of lamb.

PubMed

Pettorossi, V E; Filippi, G M

1981-09-01

The role of extraocular muscle (EOM) proprioceptors on eye motility has been investigated in lambs on "encéphale isolé", by evaluating the tension of EOMs at various lengths and velocities of stretch before and after proprioceptive blocks. The EOM tension, in the absence of proprioceptive input, was higher than in normal conditions. Such an effect occurred at lengthening values greater than 3 mm of stretch from resting muscle length, corresponding to 18 degrees of eye deviation and was dependent on the velocity of the stretch, being more effective at high velocity. The muscle receptors responsible for this effect was determined by comparing the sensitivity to vibratory stimulation of spindles and tendon organs to the amount of inhibition provoked by the same stimulation on an EOM electromyographic activity. The tension inhibition appeared to be correlated to muscle spindle activation. Thus, the presence of muscle spindles can determine a reduction of the tension within the stretched muscles. This result suggests that the EOM length and velocity signals operate moment to moment reduction on the stiffness of the muscle which antagonizes eye displacement, thus facilitating the ocular movements.

A comparative analysis of the encapsulated end-organs of mammalian skeletal muscles and of their sensory nerve endings.

PubMed

Banks, R W; Hulliger, M; Saed, H H; Stacey, M J

2009-06-01

The encapsulated sensory endings of mammalian skeletal muscles are all mechanoreceptors. At the most basic functional level they serve as length sensors (muscle spindle primary and secondary endings), tension sensors (tendon organs), and pressure or vibration sensors (lamellated corpuscles). At a higher functional level, the differing roles of individual muscles in, for example, postural adjustment and locomotion might be expected to be reflected in characteristic complements of the various end-organs, their sensory endings and afferent nerve fibres. This has previously been demonstrated with regard to the number of muscle-spindle capsules; however, information on the other types of end-organ, as well as the complements of primary and secondary endings of the spindles themselves, is sporadic and inconclusive regarding their comparative provision in different muscles. Our general conclusion that muscle-specific variability in the provision of encapsulated sensory endings does exist demonstrates the necessity for the acquisition of more data of this type if we are to understand the underlying adaptive relationships between motor control and the structure and function of skeletal muscle. The present quantitative and comparative analysis of encapsulated muscle afferents is based on teased, silver-impregnated preparations. We begin with a statistical analysis of the number and distribution of muscle-spindle afferents in hind-limb muscles of the cat, particularly tenuissimus. We show that: (i) taking account of the necessity for at least one primary ending to be present, muscles differ significantly in the mean number of additional afferents per spindle capsule; (ii) the frequency of occurrence of spindles with different sensory complements is consistent with a stochastic, rather than deterministic, developmental process; and (iii) notwithstanding the previous finding, there is a differential distribution of spindles intramuscularly such that the more complex ones tend

Sensory Feedback in Interlimb Coordination: Contralateral Afferent Contribution to the Short-Latency Crossed Response during Human Walking.

PubMed

Gervasio, Sabata; Voigt, Michael; Kersting, Uwe G; Farina, Dario; Sinkjær, Thomas; Mrachacz-Kersting, Natalie

2017-01-01

A constant coordination between the left and right leg is required to maintain stability during human locomotion, especially in a variable environment. The neural mechanisms underlying this interlimb coordination are not yet known. In animals, interneurons located within the spinal cord allow direct communication between the two sides without the need for the involvement of higher centers. These may also exist in humans since sensory feedback elicited by tibial nerve stimulation on one side (ipsilateral) can affect the muscles activation in the opposite side (contralateral), provoking short-latency crossed responses (SLCRs). The current study investigated whether contralateral afferent feedback contributes to the mechanism controlling the SLCR in human gastrocnemius muscle. Surface electromyogram, kinematic and kinetic data were recorded from subjects during normal walking and hybrid walking (with the legs moving in opposite directions). An inverse dynamics model was applied to estimate the gastrocnemius muscle proprioceptors' firing rate. During normal walking, a significant correlation was observed between the magnitude of SLCRs and the estimated muscle spindle secondary afferent activity (P = 0.04). Moreover, estimated spindle secondary afferent and Golgi tendon organ activity were significantly different (P ≤ 0.01) when opposite responses have been observed, that is during normal (facilitation) and hybrid walking (inhibition) conditions. Contralateral sensory feedback, specifically spindle secondary afferents, likely plays a significant role in generating the SLCR. This observation has important implications for our understanding of what future research should be focusing on to optimize locomotor recovery in patient populations.

Spatial factors and muscle spindle input influence the generation of neuromuscular responses to stimulation of the human foot

NASA Astrophysics Data System (ADS)

Layne, Charles S.; Forth, Katharine E.; Abercromby, Andrew F. J.

2005-05-01

Removal of the mechanical pressure gradient on the soles leads to physiological adaptations that ultimately result in neuromotor degradation during spaceflight. We propose that mechanical stimulation of the soles serves to partially restore the afference associated with bipedal loading and assists in attenuating the negative neuromotor consequences of spaceflight. A dynamic foot stimulus device was used to stimulate the soles in a variety of conditions with different stimulation locations, stimulation patterns and muscle spindle input. Surface electromyography revealed the lateral side of the sole elicited the greatest neuromuscular response in ankle musculature, followed by the medial side, then the heel. These responses were modified by preceding stimulation. Neuromuscular responses were also influenced by the level of muscle spindle input. These results provide important information that can be used to guide the development of a "passive" countermeasure that relies on sole stimulation and can supplement existing exercise protocols during spaceflight.

Experimental masseter muscle pain alters jaw-neck motor strategy.

PubMed

Wiesinger, B; Häggman-Henrikson, B; Hellström, F; Wänman, A

2013-08-01

A functional integration between the jaw and neck regions has been demonstrated during normal jaw function. The effect of masseter muscle pain on this integrated motor behaviour in man is unknown. The aim of this study was to investigate the effect of induced masseter muscle pain on jaw-neck movements during a continuous jaw opening-closing task. Sixteen healthy men performed continuous jaw opening-closing movements to a target position, defined as 75% of the maximum jaw opening. Each subject performed two trials without pain (controls) and two trials with masseter muscle pain, induced with hypertonic saline as a single injection. Simultaneous movements of the mandible and the head were registered with a wireless optoelectronic three-dimensional recording system. Differences in movement amplitudes between trials were analysed with Friedman's test and corrected Wilcoxon matched pairs test. The head movement amplitudes were significantly larger during masseter muscle pain trials compared with control. Jaw movement amplitudes did not differ significantly between any of the trials after corrected Wilcoxon tests. The ratio between head and jaw movement amplitudes was significantly larger during the first pain trial compared with control. Experimental masseter muscle pain in humans affected integrated jaw-neck movements by increasing the neck component during continuous jaw opening-closing tasks. The findings indicate that pain can alter the strategy for jaw-neck motor control, which further underlines the functional integration between the jaw and neck regions. This altered strategy may have consequences for development of musculoskeletal pain in the jaw and neck regions. © 2012 European Federation of International Association for the Study of Pain Chapters.

Permanent reorganization of Ia afferent synapses on motoneurons after peripheral nerve injuries

PubMed Central

Alvarez, Francisco J.; Bullinger, Katie L.; Titus, Haley E.; Nardelli, Paul; Cope, Timothy C.

2010-01-01

After peripheral nerve injuries to a motor nerve the axons of motoneurons and proprioceptors are disconnected from the periphery and monosynaptic connections from group I afferents and motoneurons become diminished in the spinal cord. Following successful reinnervation in the periphery, motor strength, proprioceptive sensory encoding, and Ia afferent synaptic transmission on motoneurons partially recover. Muscle stretch reflexes, however, never recover and motor behaviors remain uncoordinated. In this review, we summarize recent findings that suggest that lingering motor dysfunction might be in part related to decreased connectivity of Ia afferents centrally. First, sensory afferent synapses retract from lamina IX causing a permanent relocation of the inputs to more distal locations and significant disconnection from motoneurons. Second, peripheral reconnection between proprioceptive afferents and muscle spindles is imperfect. As a result, a proportion of sensory afferents that retain central connections with motoneurons might not reconnect appropriately in the periphery. A hypothetical model is proposed in which the combined effect of peripheral and central reconnection deficits might explain the failure of muscle stretch to initiate or modulate firing of many homonymous motoneurons. PMID:20536938

Jaw-Dropping: Functional Variation in the Digastric Muscle in Bats.

PubMed

Curtis, Abigail A; Santana, Sharlene E

2018-02-01

Diet and feeding behavior in mammals is strongly linked to the morphology of their feeding apparatus. Cranio-muscular morphology determines how wide, forcefully, and quickly the jaw can be opened or closed, which limits the size and material properties of the foods that a mammal can eat. Most studies of feeding performance in mammals have focused on skull form and jaw muscles involved in generating bite force, but few explore how jaw abduction is related to feeding performance. In this study, we explored how the morphology of the digastric muscle, the primary jaw abducting muscle in mammals, and its jaw lever mechanics are related to diet in morphologically diverse noctilionoid bats. Results showed that insectivorous bats have strong digastric muscles associated with proportionally long jaws, which suggests these species can open their jaws quickly and powerfully during prey capture and chewing. Short snouted frugivorous bats exhibit traits that would enable them to open their jaws proportionally wider to accommodate the large fruits that they commonly feed on. Our results support the hypothesis that digastric muscle and jaw morphology are correlated with diet in bats, and that our results may also apply to other groups of mammals. Anat Rec, 301:279-290, 2018. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.

Does metabosensitive afferent fibers activity differ from slow- and fast-twitch muscles?

PubMed

Caron, Guillaume; Decherchi, Patrick; Marqueste, Tanguy

2015-09-01

This study was designed to investigate the metabosensitive afferent response evoked by electrically induced fatigue (EIF), lactic acid (LA) and potassium chloride (KCl) in three muscle types. We recorded the activity of groups III-IV afferents originating from soleus, gastrocnemius and tibialis anterior muscles. Our data showed a same pattern of response in the three muscles after chemical injections, i.e., a bell curve with maximal discharge rate at 1 mM for LA injections and a linear relationship between KCl concentrations and the afferent discharge rate. Furthermore, a stronger response was recorded after EIF in the gastrocnemius muscle compared to the two other muscles. The change in afferent discharge after 1 mM LA injection was higher for the gastrocnemius muscle compared to the response obtained with the corresponding concentration applied in the two other muscles, whereas changes to KCl injections did not dramatically differ between the three muscles. We conclude that anatomical (mass, phenotype, vascularization, receptor and afferent density…) and functional (flexor vs. extensor) differences between muscles could explain the amplitude of these responses.

Cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS) with chronic cough and preserved muscle stretch reflexes: evidence for selective sparing of afferent Ia fibres.

PubMed

Infante, Jon; García, Antonio; Serrano-Cárdenas, Karla M; González-Aguado, Rocío; Gazulla, José; de Lucas, Enrique M; Berciano, José

2018-06-01

The aim of this study was to describe five patients with cerebellar ataxia, neuropathy and vestibular areflexia syndrome (CANVAS) with chronic cough and preserved limb muscle stretch reflexes. All five patients were in the seventh decade of age, their gait imbalance having been initiated in the fifth decade. In four patients cough antedated gait imbalance between 15 and 29 years; cough was spasmodic and triggered by variable factors. Established clinical picture included severe hypopallesthesia predominating in the lower limbs with postural imbalance, and variable degree of cerebellar axial and appendicular ataxia, dysarthria and horizontal gaze-evoked nystagmus. Upper- and lower-limb tendon jerks were preserved, whereas jaw jerk was absent. Vestibular function testing showed bilateral impairment of the vestibulo-ocular reflex. Nerve conduction studies demonstrated normal motor conduction parameters and absence or severe attenuation of sensory nerve action potentials. Somatosensory evoked potentials were absent or severely attenuated. Biceps and femoral T-reflex recordings were normal, while masseter reflex was absent or attenuated. Sympathetic skin responses were normal. Cranial MRI showed vermian and hemispheric cerebellar atrophy predominating in lobules VI, VII and VIIa. We conclude that spasmodic cough may be an integral part of the clinical picture in CANVAS, antedating the appearance of imbalance in several decades and that sparing of muscle spindle afferents (Ia fibres) is probably the pathophysiological basis of normoreflexia.

Rhythmic chewing with oral jaws in teleost fishes: a comparison with amniotes.

PubMed

Gintof, Chris; Konow, Nicolai; Ross, Callum F; Sanford, Christopher P J

2010-06-01

Intra-oral prey processing (chewing) using the mandibular jaws occurs more extensively among teleost fishes than previously documented. The lack of muscle spindles, gamma-motoneurons and periodontal afferents in fishes makes them useful for testing hypotheses regarding the relationship between these sensorimotor components and rhythmic chewing in vertebrates. Electromyography (EMG) data from the adductor mandibulae (AM) were used to quantify variation in chew cycle duration in the bowfin Amia, three osteoglossomorphs (bony-tongues), four salmonids and one esocid (pike). All species chewed prey using their oral jaw in repetitive trains of between 3 and 30 consecutive chews, a pattern that resembles cyclic chewing in amniote vertebrates. Variance in rhythmicity was compared within and between lineages using coefficients of variation and Levene's test for homogeneity of variance. These comparisons revealed that some teleosts exhibit degrees of rhythmicity that are comparable to mammalian mastication and higher than in lepidosaurs. Moreover, chew cycle durations in fishes, as in mammals, scale positively with mandible length. Chewing among basal teleosts may be rhythmic because it is stereotyped and inflexible, the result of patterned interactions between sensory feedback and a central pattern generator, because the lack of a fleshy tongue renders jaw-tongue coordination unnecessary and/or because stereotyped opening and closing movements are important for controlling fluid flow in the oral cavity.

The relationships among jaw-muscle fiber architecture, jaw morphology, and feeding behavior in extant apes and modern humans.

PubMed

Taylor, Andrea B; Vinyard, Christopher J

2013-05-01

The jaw-closing muscles are responsible for generating many of the forces and movements associated with feeding. Muscle physiologic cross-sectional area (PCSA) and fiber length are two architectural parameters that heavily influence muscle function. While there have been numerous comparative studies of hominoid and hominin craniodental and mandibular morphology, little is known about hominoid jaw-muscle fiber architecture. We present novel data on masseter and temporalis internal muscle architecture for small- and large-bodied hominoids. Hominoid scaling patterns are evaluated and compared with representative New- (Cebus) and Old-World (Macaca) monkeys. Variation in hominoid jaw-muscle fiber architecture is related to both absolute size and allometry. PCSAs scale close to isometry relative to jaw length in anthropoids, but likely with positive allometry in hominoids. Thus, large-bodied apes may be capable of generating both absolutely and relatively greater muscle forces compared with smaller-bodied apes and monkeys. Compared with extant apes, modern humans exhibit a reduction in masseter PCSA relative to condyle-M1 length but retain relatively long fibers, suggesting humans may have sacrificed relative masseter muscle force during chewing without appreciably altering muscle excursion/contraction velocity. Lastly, craniometric estimates of PCSAs underestimate hominoid masseter and temporalis PCSAs by more than 50% in gorillas, and overestimate masseter PCSA by as much as 30% in humans. These findings underscore the difficulty of accurately estimating jaw-muscle fiber architecture from craniometric measures and suggest models of fossil hominin and hominoid bite forces will be improved by incorporating architectural data in estimating jaw-muscle forces. Copyright © 2013 Wiley Periodicals, Inc.

The Effect of Functional Mandibular Shift on the Muscle Spindle Systems in Head-Neck Muscles and the Related Neurotransmitter Histamine.

PubMed

Du, Bing-Li; Li, Jiang-Ning; Guo, Hong-Ming; Li, Song; Liu, Biao

2017-09-01

The aim of this study is to explore the effects of abnormal occlusion and functional recovery caused by functional mandible deviation on the head and neck muscles and muscle spindle sensory-motor system by electrophysiological response and endogenous monoamine neurotransmitters' distribution in the nucleus of the spinal tract. Seven-week-old male Wistar rats were randomly divided into 7 groups: normal control group, 2W experimental control group, 2W functional mandible deviation group, 2W functional mandible deviation recovery group, 4W experimental control group, 4W functional mandible deviation group, 4W functional mandible deviation recovery group. Chewing muscles, digastric muscle, splenius, and trapezius muscle spindles electrophysiological response activities at the opening and closing state were recorded. And then the chewing muscles, digastric, splenius, trapezius, and neck trigeminal nucleus were taken for histidine decarboxylase (HDC) detection by high performance liquid chromatography (HPLC), immunofluorescence, and reverse-transcription polymerase chain reaction (RT-PCR). Histamine receptor proteins in the neck nucleus of the spinal tract were also examined by immunofluorescence and RT-PCR. Electromyography activity of chewing muscles, digastric, and splenius muscle was significantly asymmetric; the abnormal muscle electromyography activity was mainly detected at the ipsilateral side. After functional mandibular deviation, muscle sensitivity on the ipsilateral sides of the chewing muscle and splenius decreased, muscle excitement weakened, modulation depth decreased, and the muscle spindle afferent impulses of excitation transmission speed slowed down. Changes for digastric muscle electrical activity were contrary. The functions recovered at different extents after removing the deflector. However, trapezius in all the experimental groups and recovery groups exhibited bilateral symmetry electrophysiological responses, and no significant difference

Retention of Pax3 expression in satellite cells of muscle spindles.

PubMed

Kirkpatrick, Lisa J; Yablonka-Reuveni, Zipora; Rosser, Benjamin W C

2010-04-01

Intrafusal fibers within muscle spindles retain features characteristic of immaturity, unlike the larger and more numerous extrafusal fibers constituting the bulk of skeletal muscle. Satellite cells (SCs), myogenic progenitors, are detected on the surfaces of both intrafusal and extrafusal fibers, but little is known of spindle SCs. We have recently demonstrated that, like their extrafusal counterparts, SCs in muscle spindles of posthatch chickens express paired box transcription factor 7 (Pax7) protein. During vertebrate embryogenesis, myogenic progenitors express both Pax7 and Pax3 proteins. In postnatal mice, Pax3 appears in rare SC subsets, whereas Pax7 is expressed by all SCs within extrafusal fibers. Here we test the hypothesis that Pax3 protein maintains localized expression within SCs of muscle spindles. Immunohistochemical techniques were used to identify SCs by their Pax7 expression within anterior latissimus dorsi muscle excised from posthatch chickens of various ages. A greater percentage of SCs express Pax3 within intrafusal than extrafusal fibers at each age, and the proportion of SCs expressing Pax3 declines with aging. This is the first study to localize Pax3 expression in posthatch avian muscle and within SCs of muscle spindles. We suggest that Pax3-positive SCs are involved in fiber maintenance.

Comparative jaw muscle anatomy in kangaroos, wallabies, and rat-kangaroos (marsupialia: macropodoidea).

PubMed

Warburton, Natalie Marina

2009-06-01

The jaw muscles were studied in seven genera of macropodoid marsupials with diets ranging from mainly fungi in Potorous to grass in Macropus. Relative size, attachments, and lamination within the jaw adductor muscles varied between macropodoid species. Among macropodine species, the jaw adductor muscle proportions vary with feeding type. The relative mass of the masseter is roughly consistent, but grazers and mixed-feeders (Macropus and Lagostrophus) had relatively larger medial pterygoids and smaller temporalis muscles than the browsers (Dendrolagus, Dorcopsulus, and Setonix). Grazing macropods show similar jaw muscle proportions to "ungulate-grinding" type placental mammals. The internal architecture of the jaw muscles also varies between grazing and browsing macropods, most significantly, the anatomy of the medial pterygoid muscle. Potoroines have distinctly different jaw muscle proportions to macropodines. The masseter muscle group, in particular, the superficial masseter is enlarged, while the temporalis group is relatively reduced. Lagostrophus fasciatus is anatomically distinct from other macropods with respect to its masticatory muscle anatomy, including enlarged superficial medial pterygoid and deep temporalis muscles, an anteriorly inflected masseteric process, and the shape of the mandibular condyle. The enlarged triangular pterygoid process of the sphenoid bone, in particular, is distinctive of Lagsotrophus. (c) 2009 Wiley-Liss, Inc.

Effects from fine muscle and cutaneous afferents on spinal locomotion in cats

PubMed Central

Kniffki, K.-D.; Schomburg, E. D.; Steffens, H.

1981-01-01

1. The effects of chemically activated fine muscle afferents (groups III and IV) and electrically activated cutaneous afferents on motoneuronal discharges were studied before and during fictive locomotion induced pharmacologically by i.v. administration of nialamide and l-DOPA in high spinal cats. Efferent activity was recorded simultaneously from nerve filaments to ipsi- and contralateral extensor and flexor muscles. In addition, intracellular recordings were made from lumbar α-motoneurones. 2. After nialamide but before treatment with l-DOPA, in some cases, transient locomotor-like discharges were induced by an increased activity in fine muscle afferents. The response pattern in nerves to both hind limbs could be different showing e.g. only transient alternating activity between knee flexor and extensor of one limb but not of the other one. 3. Treatment with l-DOPA did not always cause fictive locomotion. Often not all motoneurone pools showed rhythmic activity. In these cases stimulation of group III and IV muscle afferents usually caused transient periodic activity. In cases with apparent rhythmic activity, algesic stimulation of the gastrocnemius—soleus muscle caused an accentuation of the rhythm by a more abrupt transition from the active phase to the non-active interval. Again, the response patterns on both sides were not uniform in all cases. 4. A second type of response to activation of fine muscle afferents had a quite different character: the rhythmic activity was more or less completely overridden by a strong transient tonic hyperactivity or the rhythm was transiently blocked. These phenomena did not occur in the same way in all nerves. 5. Electrical stimulation of cutaneous nerves of the hind limb generally induced the same response pattern as chemical stimulation of the group III and IV muscle afferents. The effects varied depending on the stimulus strength and the nerve. 6. The results revealed that cutaneous and fine muscle afferents not only

Myofiber turnover is used to retrofit frog jaw muscles during metamorphosis.

PubMed

Alley, K E

1989-01-01

Metamorphic reorganization of the head in anuran amphibians entails abrupt restructuring of the jaw complex as larval feeding structures are transformed into their adult configurations. In this morphometric study, light microscopy wa used to analyze the larval maturation and metamorphic transfiguration of the adductor jaw muscles in the leopard frog (Rana pipiens). Larval jaw muscles, first established during embryogenesis, continue to grow by fiber addition until prometamorphosis, stage XII. Thereafter, fiber number remains stable but additional muscle growth continues by hypertrophy of the individual fibers until metamorphic climax. During metamorphic stages XIX-XXIII, a complete involution of all larval myofibers occurs. Simultaneously, within the same muscle beds, a second wave of myogenesis produces myoblasts which are the precursors of adult jaw myofibers. New muscle fibers continue to be added to these muscles well after the completion of metamorphosis; however, the total duration of the postmetamorphic myogenic period has not been defined. These observations provide clear evidence that the entir population of primary myofibers used in larval oral activity disappears from the adductor muscle beds and is replaced by a second wave of myogenesis commencing during climax. These findings indicate that the adductor jaw muscles are prepared for adult feeding by a complicated cellular process that retrofits existing muscle beds with a completely new complement of myofibers.

Central projections and entries of capsaicin-sensitive muscle afferents.

PubMed

Della Torre, G; Lucchi, M L; Brunetti, O; Pettorossi, V E; Clavenzani, P; Bortolami, R

1996-03-25

The entry pathway and central distribution of A delta and C muscle afferents within the central nervous system (CNS) were investigated by combining electron microscopy and electrophysiological analysis after intramuscular injection of capsaicin. The drug was injected into the rat lateral gastrocnemius (LG) and extraocular (EO) muscles. The compound action potentials of LG nerve and the evoked field potentials recorded in semilunar ganglion showed an immediate and permanent reduction in A delta and C components. The morphological data revealed degenerating unmyelinated axons and terminals in the inner sublamina II and in the border of laminae I-II of the dorsal horn at L4-L5 and C1-C2 (subnucleus caudalis trigemini) spinal cord segments. Most degenerating terminals were the central bouton (C) of type I and II synaptic glomeruli. Furthermore, degenerating peripheral axonal endings (V2) presynaptic to normal C were found. Since V2 were previously found degenerated after cutting the oculomotor nerve (ON) or L4 ventral root, we conclude that some A delta and C afferents from LG and EO muscles entering the CNS by ON or ventral roots make axoaxonic synapses on other primary afferents to promote an afferent control of sensory input.

Functional Organization of Cutaneous and Muscle Afferent Synapses onto Immature Spinal Lamina I Projection Neurons

PubMed Central

Li, Jie

2017-01-01

It is well established that sensory afferents innervating muscle are more effective at inducing hyperexcitability within spinal cord circuits compared with skin afferents, which likely contributes to the higher prevalence of chronic musculoskeletal pain compared with pain of cutaneous origin. However, the mechanisms underlying these differences in central nociceptive signaling remain incompletely understood, as nothing is known about how superficial dorsal horn neurons process sensory input from muscle versus skin at the synaptic level. Using a novel ex vivo spinal cord preparation, here we identify the functional organization of muscle and cutaneous afferent synapses onto immature rat lamina I spino-parabrachial neurons, which serve as a major source of nociceptive transmission to the brain. Stimulation of the gastrocnemius nerve and sural nerve revealed significant convergence of muscle and cutaneous afferent synaptic input onto individual projection neurons. Muscle afferents displayed a higher probability of glutamate release, although short-term synaptic plasticity was similar between the groups. Importantly, muscle afferent synapses exhibited greater relative expression of Ca2+-permeable AMPARs compared with cutaneous inputs. In addition, the prevalence and magnitude of spike timing-dependent long-term potentiation were significantly higher at muscle afferent synapses, where it required Ca2+-permeable AMPAR activation. Collectively, these results provide the first evidence for afferent-specific properties of glutamatergic transmission within the superficial dorsal horn. A larger propensity for activity-dependent strengthening at muscle afferent synapses onto developing spinal projection neurons could contribute to the enhanced ability of these sensory inputs to sensitize central nociceptive networks and thereby evoke persistent pain in children following injury. SIGNIFICANCE STATEMENT The neurobiological mechanisms underlying the high prevalence of chronic

The responses of muscle spindles to small, slow movements in passive muscle and during fusimotor activity.

PubMed

Wise, A K; Gregory, J E; Proske, U

1999-03-06

We have previously shown that movement detection thresholds at the human elbow joint were less than a degree of joint rotation in the passive limb but were higher if they were measured while subjects co-contracted elbow muscles [A.K. Wise, J.E. Gregory, U. Proske, J. Physiol., 508 (1998) 325-330]. Here we report observations on the responses of muscle spindles of the soleus muscle of the anaesthetised cat to determine their ability to signal small length changes in the passive muscle and during a contraction, under conditions resembling those of the human experiments. After appropriate conditioning of the muscle to control for history effects, primary endings of muscle spindles showed thresholds to ramp stretch at 20 micrometers s-1 of between less than 5 micrometers and 15 micrometers, which translates to 0.05 degrees -0.15 degrees of human elbow joint rotation. Thresholds were much higher following conditioning to introduce slack in the muscle. Since during a voluntary contraction there is likely to be alpha:gamma co-activation, responses of spindles were also recorded during slow stretches (100 micrometers at 20 micrometers s-1) during static fusimotor stimulation, dynamic fusimotor stimulation, combined fusimotor stimulation and fusimotor plus skeletomotor stimulation. Invariably, responses to passive stretch were larger than during motor stimulation. It is concluded that spindles are sensitive enough to signal fractions of a degree of elbow joint rotation and that the rise in threshold observed during a voluntary contraction may be accounted for by the actions of fusimotor and skeletomotor axons on spindle stretch responses. Copyright 1999 Elsevier Science B.V.

Influence of botulinum toxin on rabbit jaw muscle activity and anatomy.

PubMed

Korfage, J A M; Wang, Jeffrey; Lie, S H J T J; Langenbach, Geerling E J

2012-05-01

Muscles can adapt their fiber properties to accommodate to new conditions. We investigated the extent to which a decrease in muscle activation can cause an adaptation of fiber properties in synergistic and antagonistic jaw muscles. Three months after the injection of botulinum toxin type A in one masseter (anterior or posterior) muscle changes in fiber type composition and fiber cross-sectional areas in jaw muscles were studied at the microscopic level. The injected masseter showed a steep increase in myosin type IIX fibers, whereas fast fibers decreased by about 50% in size. Depending on the injection site, both synergistic and antagonistic muscles showed a significant increase in the size of their fast IIA fibers, sometimes combined with an increased number of IIX fibers. Silencing the activity in the masseter not only causes changes in the fibers of the injected muscle but also leads to changes in other jaw muscles. Copyright © 2012 Wiley Periodicals, Inc.

New insights into dinosaur jaw muscle anatomy.

PubMed

Holliday, Casey M

2009-09-01

Jaw muscles are key components of the head and critical to testing hypotheses of soft-tissue homology, skull function, and evolution. Dinosaurs evolved an extraordinary diversity of cranial forms adapted to a variety of feeding behaviors. However, disparate evolutionary transformations in head shape and function among dinosaurs and their living relatives, birds and crocodylians, impair straightforward reconstructions of muscles, and other important cephalic soft tissues. This study presents the osteological correlates and inferred soft tissue anatomy of the jaw muscles and relevant neurovasculature in the temporal region of the dinosaur head. Hypotheses of jaw muscle homology were tested across a broad range archosaur and sauropsid taxa to more accurately infer muscle attachments in the adductor chambers of non-avian dinosaurs. Many dinosaurs likely possessed m. levator pterygoideus, a trait shared with lepidosaurs but not extant archosaurs. Several major clades of dinosaurs (e.g., Ornithopoda, Ceratopsidae, Sauropoda) eliminated the epipterygoid, thus impacting interpretations of m. pseudotemporalis profundus. M. pseudotemporalis superficialis most likely attached to the caudoventral surface of the laterosphenoid, a trait shared with extant archosaurs. Although mm. adductor mandibulae externus profundus and medialis likely attached to the caudal half of the dorsotemporal fossa and coronoid process, clear osteological correlates separating the individual bellies are rare. Most dinosaur clades possess osteological correlates indicative of a pterygoideus ventralis muscle that attaches to the lateral surface of the mandible, although the muscle may have extended as far as the jugal in some taxa (e.g., hadrosaurs, tyrannosaurs). The cranial and mandibular attachments of mm adductor mandibulae externus superficialis and adductor mandibulae posterior were consistent across all taxa studied. These new data greatly increase the interpretive resolution of head anatomy in

Muscle Spindle Traffic in Functionally Unstable Ankles During Ligamentous Stress

PubMed Central

Needle, Alan R.; Charles B. (Buz), Swanik; Farquhar, William B.; Thomas, Stephen J.; Rose, William C.; Kaminski, Thomas W.

2013-01-01

Context: Ankle sprains are common in athletes, with functional ankle instability (FAI) developing in approximately half of cases. The relationship between laxity and FAI has been inconclusive, suggesting that instability may be caused by insufficient sensorimotor function and dynamic restraint. Research has suggested that deafferentation of peripheral mechanoreceptors potentially causes FAI; however, direct evidence confirming peripheral sensory deficits has been elusive because previous investigators relied upon subjective proprioceptive tests. Objective: To develop a method for simultaneously recording peripheral sensory traffic, joint forces, and laxity and to quantify differences between healthy ankles and those with reported instability. Design: Case-control study. Setting: University laboratory. Patients or Other Participants: A total of 29 participants (age = 20.9 ± 2.2 years, height = 173.1 ± 8.9 cm, mass = 74.5 ± 12.7 kg) stratified as having healthy (HA, n = 19) or unstable ankles (UA, n = 10). Intervention(s): Sensory traffic from muscle spindle afferents in the peroneal nerve was recorded with microneurography while anterior (AP) and inversion (IE) stress was applied to ligamentous structures using an ankle arthrometer under test and sham conditions. Main Outcome Measure(s): Laxity (millimeters or degrees) and amplitude of sensory traffic (percentage) were determined at 0, 30, 60, 90, and 125 N of AP force and at 0, 1, 2, 3, and 4 Nm of IE torque. Two-factor repeated-measures analyses of variance were used to determine differences between groups and conditions. Results: No differences in laxity were observed between groups (P > .05). Afferent traffic increased with increased force and torque in test trials (P < .001). The UA group displayed decreased afferent activity at 30 N of AP force compared with the HA group (HA: 30.2% ± 9.9%, UA: 17.1% ± 16.1%, P < .05). Conclusions: The amplitude of sensory traffic increased simultaneously with greater

Effect of inaction on function of fast and slow muscle spindles

NASA Technical Reports Server (NTRS)

Arutyunyan, R. S.

1980-01-01

There is no data on the comparative effect of tenotomy on the function of the muscle spindles of fast and slow muscles. This study covers this question. The experiments were conducted on cats. The musuculus extensor digitorum longus (m. EDL) was selected as the fast muscle, and the musculus soleus (m. Sol.) as the slow. In a comparison of the spontaneous activity of primary and secondary endings of the fast and slow muscle spindles (i.e., the activity with complete relaxation of the muscles) normally no difference between them was successfully found. The authors recorded the integrative, and not the individual activity, and secondly, under conditions of such recording technique, those slight changes that are observed in the fast muscle receptors could remain unnoticed.

Contribution of jaw muscle size and craniofacial morphology to human bite force magnitude.

PubMed

Raadsheer, M C; van Eijden, T M; van Ginkel, F C; Prahl-Andersen, B

1999-01-01

The existence of an interaction among bite force magnitude, jaw muscle size (e.g., cross-sectional area, thickness), and craniofacial morphology is widely accepted. Bite force magnitude depends on the size of the jaw muscles and the lever arm lengths of bite force and muscle forces, which in turn are dictated by craniofacial morphology. In this study, the relative contributions of craniofacial morphology and jaw muscle thickness to the bite force magnitude were studied. In 121 adult individuals, both magnitude and direction of the maximal voluntary bite force were registered. Craniofacial dimensions were measured by anthropometrics and from lateral radiographs. The thicknesses of the masseter, temporal, and digastric muscles were registered by ultrasonography. After a factor analysis was applied to the anthropometric and cephalometric dimensions, the correlation between bite force magnitude, on the one hand, and the "craniofacial factors" and jaw muscle thicknesses, on the other, was assessed by stepwise multiple regression. Fifty-eight percent of the bite force variance could be explained. From the jaw muscles, only the thickness of the masseter muscle correlated significantly with bite force magnitude. Bite force magnitude also correlated significantly positively with vertical and transverse facial dimensions and the inclination of the midface, and significantly negatively with mandibular inclination and occlusal plane inclination. The contribution of the masseter muscle to the variation in bite force magnitude was higher than that of the craniofacial factors.

Jaw muscle fiber type distribution in Hawaiian gobioid stream fishes: histochemical correlations with feeding ecology and behavior.

PubMed

Maie, Takashi; Meister, Andrew B; Leonard, Gerald L; Schrank, Gordon D; Blob, Richard W; Schoenfuss, Heiko L

2011-12-01

Differences in fiber type distribution in the axial muscles of Hawaiian gobioid stream fishes have previously been linked to differences in locomotor performance, behavior, and diet across species. Using ATPase assays, we examined fiber types of the jaw opening sternohyoideus muscle across five species, as well as fiber types of three jaw closing muscles (adductor mandibulae A1, A2, and A3). The jaw muscles of some species of Hawaiian stream gobies contained substantial red fiber components. Some jaw muscles always had greater proportions of white muscle fibers than other jaw muscles, independent of species. In addition, comparing across species, the dietary generalists (Awaous guamensis and Stenogobius hawaiiensis) had a lower proportion of white muscle fibers in all jaw muscles than the dietary specialists (Lentipes concolor, Sicyopterus stimpsoni, and Eleotris sandwicensis). Among Hawaiian stream gobies, generalist diets may favor a wider range of muscle performance, provided by a mix of white and red muscle fibers, than is typical of dietary specialists, which may have a higher proportion of fast-twitch white fibers in jaw muscles to help meet the demands of rapid predatory strikes or feeding in fast-flowing habitats. Copyright © 2011 Elsevier GmbH. All rights reserved.

Scaling and Accommodation of Jaw Adductor Muscles in Canidae

PubMed Central

Kemp, Graham J.; Jeffery, Nathan

2016-01-01

ABSTRACT The masticatory apparatus amongst closely related carnivoran species raises intriguing questions about the interplay between allometry, function, and phylogeny in defining interspecific variations of cranial morphology. Here we describe the gross structure of the jaw adductor muscles of several species of canid, and then examine how the muscles are scaled across the range of body sizes, phylogenies, and trophic groups. We also consider how the muscles are accommodated on the skull, and how this is influenced by differences of endocranial size. Data were collected for a suite of morphological metrics, including body mass, endocranial volume, and muscle masses and we used geometric morphometric shape analysis to reveal associated form changes. We find that all jaw adductor muscles scale isometrically against body mass, regardless of phylogeny or trophic group, but that endocranial volume scales with negative allometry against body mass. These findings suggest that head shape is partly influenced by the need to house isometrically scaling muscles on a neurocranium scaling with negative allometry. Principal component analysis suggests that skull shape changes, such as the relatively wide zygomatic arches and large sagittal crests seen in species with higher body masses, allow the skull to accommodate a relative enlargement of the jaw adductors compared with the endocranium. Anat Rec, 299:951–966, 2016. © 2016 The Authors The Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology Published by Wiley Periodicals, Inc. PMID:27103346

Fatigue-induced changes in group IV muscle afferent activity: differences between high- and low-frequency electrically induced fatigues.

PubMed

Darques, J L; Jammes, Y

1997-03-07

Recordings of group IV afferent activity of tibialis anterior muscle were performed in paralysed rabbits during runs of electrically induced fatigue produced by direct muscle stimulation at a high (100 Hz, high-frequency fatigue HFF) or a low rate (10 Hz, low-frequency fatigue LFF). In addition to analysis of afferent nerve action potentials, muscle force and compound muscle action potentials (M waves) elicited by direct muscle stimulation with single shocks were recorded. Changes in M wave configuration were used as an index of the altered propagation of membrane potentials and the associated efflux of potassium from muscle fibers. The data show that increased group IV afferent activity occurred during LFF as well as HFF trials and developed parallel with force failure. Enhanced afferent activity was significantly higher during LFF (maximal delta f(impulses) = 249 +/- 35%) than HFF (147 +/- 45%). No correlation was obtained between the responses of group IV afferents to LFF or to pressure exerted on tibialis anterior muscle. On the other hand, decreased M wave amplitude was minimal with LFF while it was pronounced with HFF. Close correlations were found between fatigue-induced activation of group IV afferents and decreases in force or M wave amplitude, but their strength was significantly higher with LFF compared to HFF. Thus, electrically induced fatigue activates group IV muscle afferents with a prominent effect of low-frequency stimulation. The mechanism of muscle afferent stimulation does not seem to be due to the sole increase in extracellular potassium concentration, but also by the efflux of muscle metabolites, present during fatiguing contractions at low rate of stimulation.

Effect of spinal manipulation on the development of history-dependent responsiveness of lumbar paraspinal muscle spindles in the cat

PubMed Central

Cao, Dong-Yuan; Pickar, Joel G.

2014-01-01

We determined whether spinal manipulation could prevent and/or reverse the decrease and increase in paraspinal muscle spindle responsiveness caused respectively by lengthening and shortening histories of the lumbar muscles. Single unit spindle activity from multifidus and longissimus muscles was recorded in the L6 dorsal root in anesthetized cats. Muscle history was created and spinal manipulation delivered (thrust amplitude: 1.0mm, duration: 100ms) using a feedback-controlled motor attached to the L6 spinous process. Muscle spindle discharge to a fixed vertebral position (static test) and to vertebral movement (dynamic test) was evaluated following the lengthening and shortening histories. For the static test, changes in muscle spindle responsiveness were significantly less when spinal manipulation followed muscle history (p<0.01), but not when spinal manipulation preceded it (p>0.05). For the dynamic test, spinal manipulation did not significantly affect the history-induced change in muscle spindle responsiveness. Spinal manipulation may partially reverse the effects of muscle history on muscle spindle signaling of vertebral position. PMID:24932019

Ankle joint movements are encoded by both cutaneous and muscle afferents in humans.

PubMed

Aimonetti, Jean-Marc; Roll, Jean-Pierre; Hospod, Valérie; Ribot-Ciscar, Edith

2012-08-01

We analyzed the cutaneous encoding of two-dimensional movements by investigating the coding of movement velocity for differently oriented straight-line movements and the coding of complex trajectories describing cursive letters. The cutaneous feedback was then compared with that of the underlying muscle afferents previously recorded during the same "writing-like" movements. The unitary activity of 43 type II cutaneous afferents was recorded in the common peroneal nerve in healthy subjects during imposed ankle movements. These movements consisted first of ramp-and-hold movements imposed at two different and close velocities in seven directions and secondly of "writing-like" movements. In both cases, the responses were analyzed using the neuronal population vector model. The results show that movement velocity encoding depended on the direction of the ongoing movement. Discriminating between two velocities therefore involved processing the activity of afferent populations located in the various skin areas surrounding the moving joint, as shown by the statistically significant difference observed in the amplitude of the sum vectors. Secondly, "writing-like" movements induced cutaneous neuronal patterns of activity, which were reproducible and specific to each trajectory. Lastly, the "cutaneous neuronal trajectories," built by adding the sum vectors tip-to-tail, nearly matched both the movement trajectories and the "muscle neuronal trajectories," built from previously recorded muscle afferents. It was concluded that type II cutaneous and the underlying muscle afferents show similar encoding properties of two-dimensional movement parameters. This similarity is discussed in relation to a central gating process that would for instance increase the gain of cutaneous inputs when muscle information is altered by the fusimotor drive.

Does induced masseter muscle pain affect integrated jaw-neck movements similarly in men and women?

PubMed

Wiesinger, Birgitta; Häggman-Henrikson, Birgitta; Hellström, Fredrik; Englund, Erling; Wänman, Anders

2016-12-01

Normal jaw opening-closing involves simultaneous jaw and head-neck movements. We previously showed that, in men, integrated jaw-neck movements during jaw function are altered by induced masseter muscle pain. The aim of this study was to investigate possible sex-related differences in integrated jaw-neck movements following experimental masseter muscle pain. We evaluated head-neck and jaw movements in 22 healthy women and 16 healthy men in a jaw opening-closing task. The participants performed one control trial and one trial with masseter muscle pain induced by injection of hypertonic saline. Jaw and head movements were registered using a three-dimensional optoelectronic recording system. There were no significant sex-related differences in jaw and head movement amplitudes. Head movement amplitudes were significantly greater in the pain trials for both men and women. The proportional involvement of the neck motor system during jaw movements increased in pain trials for 13 of 16 men and for 18 of 22 women. Thus, acute pain may alter integrated jaw-neck movements, although, given the similarities between men and women, this interaction between acute pain and motor behaviour does not explain sex differences in musculoskeletal pain in the jaw and neck regions. © 2016 Eur J Oral Sci.

Capsaicin-sensitive muscle afferents modulate the monosynaptic reflex in response to muscle ischemia and fatigue in the rat.

PubMed

Della Torre, G; Brunetti, O; Pettorossi, V E

2002-01-01

The role of muscle ischemia and fatigue in modulating the monosynaptic reflex was investigated in decerebrate and spinalized rats. Field potentials and fast motoneuron single units in the lateral gastrocnemious (LG) motor pool were evoked by dorsal root stimulation. Muscle ischemia was induced by occluding the LG vascular supply and muscle fatigue by prolonged tetanic electrical stimulation of the LG motor nerve. Under muscle ischemia the monosynaptic reflex was facilitated since the size of the early and late waves of the field potential and the excitability of the motoneuron units increased. This effect was abolished after L3-L6 dorsal rhizotomy, but it was unaffected after L3-L6 ventral rhizotomy. By contrast, the monosynaptic reflex was inhibited by muscle fatiguing stimulation, and this effect did not fully depend on the integrity of the dorsal root. However, when ischemia was combined with repetitive tetanic muscle stimulation the inhibitory effect of fatigue was significantly enhanced. Both the ischemia and fatigue effects were abolished by capsaicin injected into the LG muscle at a dose that blocked a large number of group III and IV muscle afferents. We concluded that muscle ischemia and fatigue activate different groups of muscle afferents that are both sensitive to capsaicin, but enter the spinal cord through different roots. They are responsible for opposite effects, when given separately: facilitation during ischemia and inhibition during fatigue; however, in combination, ischemia enhances the responsiveness of the afferent fibres to fatigue.

The Dynamics of Voluntary Force Production in Afferented Muscle Influence Involuntary Tremor

PubMed Central

Laine, Christopher M.; Nagamori, Akira; Valero-Cuevas, Francisco J.

2016-01-01

Voluntary control of force is always marked by some degree of error and unsteadiness. Both neural and mechanical factors contribute to these fluctuations, but how they interact to produce them is poorly understood. In this study, we identify and characterize a previously undescribed neuromechanical interaction where the dynamics of voluntary force production suffice to generate involuntary tremor. Specifically, participants were asked to produce isometric force with the index finger and use visual feedback to track a sinusoidal target spanning 5–9% of each individual's maximal voluntary force level. Force fluctuations and EMG activity over the flexor digitorum superficialis (FDS) muscle were recorded and their frequency content was analyzed as a function of target phase. Force variability in either the 1–5 or 6–15 Hz frequency ranges tended to be largest at the peaks and valleys of the target sinusoid. In those same periods, FDS EMG activity was synchronized with force fluctuations. We then constructed a physiologically-realistic computer simulation in which a muscle-tendon complex was set inside of a feedback-driven control loop. Surprisingly, the model sufficed to produce phase-dependent modulation of tremor similar to that observed in humans. Further, the gain of afferent feedback from muscle spindles was critical for appropriately amplifying and shaping this tremor. We suggest that the experimentally-induced tremor may represent the response of a viscoelastic muscle-tendon system to dynamic drive, and therefore does not fall into known categories of tremor generation, such as tremorogenic descending drive, stretch-reflex loop oscillations, motor unit behavior, or mechanical resonance. Our findings motivate future efforts to understand tremor from a perspective that considers neuromechanical coupling within the context of closed-loop control. The strategy of combining experimental recordings with physiologically-sound simulations will enable thorough

Masticatory motor patterns in ungulates: a quantitative assessment of jaw-muscle coordination in goats, alpacas and horses.

PubMed

Williams, Susan H; Vinyard, Christopher J; Wall, Christine E; Hylander, William L

2007-04-01

We investigated patterns of jaw-muscle coordination during rhythmic mastication in three species of ungulates displaying the marked transverse jaw movements typical of many large mammalian herbivores. In order to quantify consistent motor patterns during chewing, electromyograms were recorded from the superficial masseter, deep masseter, posterior temporalis and medial pterygoid muscles of goats, alpacas and horses. Timing differences between muscle pairs were evaluated in the context of an evolutionary model of jaw-muscle function. In this model, the closing and food reduction phases of mastication are primarily controlled by two distinct muscle groups, triplet I (balancing-side superficial masseter and medial pterygoid and working-side posterior temporalis) and triplet II (working-side superficial masseter and medial pterygoid and balancing-side posterior temporalis), and the asynchronous activity of the working- and balancing-side deep masseters. The three species differ in the extent to which the jaw muscles are coordinated as triplet I and triplet II. Alpacas, and to a lesser extent, goats, exhibit the triplet pattern whereas horses do not. In contrast, all three species show marked asynchrony of the working-side and balancing-side deep masseters, with jaw closing initiated by the working-side muscle and the balancing-side muscle firing much later during closing. However, goats differ from alpacas and horses in the timing of the balancing-side deep masseter relative to the triplet II muscles. This study highlights interspecific differences in the coordination of jaw muscles to influence transverse jaw movements and the production of bite force in herbivorous ungulates.

Effects of ruthenium ions on the sensory terminal discharges of the frog muscle spindle.

PubMed

Ito, F; Fujitsuka, N; Komatsu, Y

1983-10-16

The presence of a mixed Na+-Ca2+ spike along the sensory terminal of the frog muscle spindle was verified. When the terminal was perfused with Ringer's solution containing 0.1-0.5 mM ruthenium red (RuR), the amplitude and duration of the spike were increased, occurring as a prolonged or a long-lasting depolarization of up to 20-30 s duration following individual afferent spikes evoked spontaneously or antidromically by electrical stimulation. In an isotonic TEA solution, the amplitude and duration of the afferent spikes were increased; however, no prolonged depolarization occurred. Adding 0.2 mM RuR to the TEA solution produced the prolonged and long-lasting depolarization. All responses disappeared in the presence of 3 microM TTX or Na+-free Ringer's solution. An impedance decrease along the terminal was observed during the prolonged or long-lasting depolarization. The prolonged depolarization was blocked by the addition of Ca2+-blockers; the afferent spikes remained. In preparations preincubated with 0.1 mM RuR, increasing CaCl2 in Ringer's solution from 0.2 mM, resulted in shortening of the duration of individual spikes with prolonged depolarization and in increase in the maximum rate of rise (MRR) of the spikes. Preincubation with higher concentrations of RuR produced higher sensitivities in the modifications of the duration and MRR to the change in [Ca2+]O. The responses were retained by adding RuR or RuCl3 to Ca2+-free Ringer's solution containing 0.1-5 mM EGTA, although all responses disappeared in Ca2+-free EGTA Ringer's solution. It is concluded that the RuR-induced prolonged response is produced by an influx of Na+.

The relationship between jaw-opening force and the cross-sectional area of the suprahyoid muscles in healthy elderly.

PubMed

Kajisa, E; Tohara, H; Nakane, A; Wakasugi, Y; Hara, K; Yamaguchi, K; Yoshimi, K; Minakuchi, S

2018-03-01

We conducted a clinical cross-sectional study to examine the relationship between jaw-opening force and the cross-sectional area of the suprahyoid muscles and whole skeletal muscle mass. Subjects were healthy 39 males and 51 females without dysphagia and sarcopenia, aged 65 years and older. Jaw-opening force was measured three times using a jaw-opening sthenometer; the maximum of these three was taken as the measurement value. The cross-sectional area of the geniohyoid and anterior belly of the digastric muscles were evaluated using ultrasonography. The skeletal muscle mass index, gait speed and grip strength were evaluated according to the diagnostic criteria of the Asian Working Group for Sarcopenia. For each sex, a multiple regression analysis determined the factors that affect jaw-opening force. Jaw-opening force was associated with the cross-sectional area of the geniohyoid muscle in males (regression coefficient [β] = 0.441, 95% confidence interval [CI] = 14.28-56.09) and females (β = 0.28, 95% CI = 3.10-54.57). Furthermore, in females only, jaw-opening force was associated with the skeletal muscle mass index (β = 0.40, 95% CI = 3.67-17.81). In contrast, jaw-opening force was not associated with the cross-sectional area of the anterior belly of the digastric muscle in either sex. In healthy elderly males and females, jaw-opening force was positively associated with the cross-sectional area of the geniohyoid muscle. However, the jaw-opening force was positively associated with the skeletal muscle mass index only in females. © 2017 John Wiley & Sons Ltd.

Electrophysiological characteristics of IB4-negative TRPV1-expressing muscle afferent DRG neurons.

PubMed

Lin, Yi-Wen; Chen, Chih-Cheng

2015-01-01

Muscle afferent neurons that express transient receptor potential vanilloid type I (TRPV1) are responsible for muscle pain associated with tissue acidosis. We have previously found that TRPV1 of isolectin B4 (IB4)-negative muscle nociceptors plays an important role in the acid-induced hyperalgesic priming and the development of chronic hyperalgesia in a mouse model of fibromyalgia. To understand the electrophysiological properties of the TRPV1-expressing muscle afferent neurons, we used whole-cell patch clamp recording to study the acid responsiveness and action potential (AP) configuration of capsaicin-sensitive neurons innervating to gastrocnemius muscle. Here we showed that IB4-negative TRPV1-expressing muscle afferent neurons are heterogeneous in terms of cell size, resting membrane potential, AP configuration, tetrodotoxin (TTX)-resistance, and acid-induced current (I acid), as well as capsaicin-induced current (I cap). TRPV1-expressing neurons were all acid-sensitive and could be divided into two acid-sensitive groups depending on an acid-induced sustained current (type I) or an acid-induced biphasic ASIC3-like current (type II). Type I TRPV1-expressing neurons were distinguishable from type II TRPV1-expressing neurons in AP overshoot, after-hyperpolarization duration, and all I acid parameters, but not in AP threshold, TTX-resistance, resting membrane potential, and I cap parameters. These differential biophysical properties of TRPV1-expressing neurons might partially annotate their different roles involved in the development and maintenance of chronic muscle pain.

Skeletal muscle afferent regulation of bioassayable growth hormone in the rat pituitary

NASA Technical Reports Server (NTRS)

Gosselink, K. L.; Grindeland, R. E.; Roy, R. R.; Zhong, H.; Bigbee, A. J.; Grossman, E. J.; Edgerton, V. R.

1998-01-01

There are forms of growth hormone (GH) in the plasma and pituitary of the rat and in the plasma of humans that are undetected by presently available immunoassays (iGH) but can be measured by bioassay (bGH). Although the regulation of iGH release is well documented, the mechanism(s) of bGH release is unclear. On the basis of changes in bGH and iGH secretion in rats that had been exposed to microgravity conditions, we hypothesized that neural afferents play a role in regulating the release of these hormones. To examine whether bGH secretion can be modulated by afferent input from skeletal muscle, the proximal or distal ends of severed hindlimb fast muscle nerves were stimulated ( approximately 2 times threshold) in anesthetized rats. Plasma bGH increased approximately 250%, and pituitary bGH decreased approximately 60% after proximal nerve trunk stimulation. The bGH response was independent of muscle mass or whether the muscles were flexors or extensors. Distal nerve stimulation had little or no effect on plasma or pituitary bGH. Plasma iGH concentrations were unchanged after proximal nerve stimulation. Although there may be multiple regulatory mechanisms of bGH, the present results demonstrate that the activation of low-threshold afferents from fast skeletal muscles can play a regulatory role in the release of bGH, but not iGH, from the pituitary in anesthetized rats.

A quantitative study of skeletofusimotor innervation in the cat peroneus tertius muscle.

PubMed Central

Jami, L; Murthy, K S; Petit, J

1982-01-01

1. Physiological tests were used to identify skeletofusimotor or beta axons to the cat peroneus tertius muscle in order to assess the proportion of beta axons in the motor supply to this muscle. 2. Static beta axons (beta S) were identified by: (a) observation of a delay between the complete block of extrafusal contraction and the failure of spindle activation upon prolonged stimulation, (b) increase of spindle excitation with stimulation frequencies above that eliciting maximal extrafusal contraction, (c) observation of 'unfused' frequencygram of spindle primary afferent discharge during stimulation of the axon at frequencies above that eliciting complete fusion of extrafusal contraction and (d) static action exerted on the response of the spindle afferent to ramp stretch. 3. Dynamic beta axons (beta D) were identified by the persistence of spindle activation after selective block of extrafusal neuromuscular junctions and by their dynamic action on spindle primary endings. 4. The actions of 116 motor axons (conduction velocity 56-104 m/sec) on ninety-five spindle afferents (fifty-seven from primary and thirty-eight from secondary endings) were examined in ten experiments. Thirty-six beta axons (31% of the total sample) were identified: twenty-four beta S (conduction velocity 69-104 m/sec) and twelve beta D (conduction velocity 56-91 m/sec). 5. Twenty (35%) primary endings were activated by a beta S and sixteen (28%) by a beta D axon. Nineteen (45%) secondary endings were activated by a beta S and five (13%) by a beta D axon. Convergence of beta D and beta S axons on the same spindle occurred in 10% of instances. beta-innervated spindles were also supplied by gamma axons. 6. Most of the beta S motor units were of the fast-fatigue resistant (FR) type, with a few units of the fast-fatigable (FF) type, and nearly all the beta D motor units were of the slow (S) type. PMID:6213764

The role of muscle spindles in the development of the monosynaptic stretch reflex

PubMed Central

Wang, Zhi; Li, LingYing

2012-01-01

Muscle sensory axons induce the development of specialized intrafusal muscle fibers in muscle spindles during development, but the role that the intrafusal fibers may play in the development of the central projections of these Ia sensory axons is unclear. In the present study, we assessed the influence of intrafusal fibers in muscle spindles on the formation of monosynaptic connections between Ia (muscle spindle) sensory axons and motoneurons (MNs) using two transgenic strains of mice. Deletion of the ErbB2 receptor from developing myotubes disrupts the formation of intrafusal muscle fibers and causes a nearly complete absence of functional synaptic connections between Ia axons and MNs. Monosynaptic connectivity can be fully restored by postnatal administration of neurotrophin-3 (NT-3), and the synaptic connections in NT-3-treated mice are as specific as in wild-type mice. Deletion of the Egr3 transcription factor also impairs the development of intrafusal muscle fibers and disrupts synaptic connectivity between Ia axons and MNs. Postnatal injections of NT-3 restore the normal strengths and specificity of Ia–motoneuronal connections in these mice as well. Severe deficits in intrafusal fiber development, therefore, do not disrupt the establishment of normal, selective patterns of connections between Ia axons and MNs, although these connections require the presence of NT-3, normally supplied by intrafusal fibers, to be functional. PMID:22490553

Effects of thrust amplitude and duration of high velocity low amplitude spinal manipulation on lumbar muscle spindle responses to vertebral position and movement

PubMed Central

Cao, Dong-Yuan; Reed, William R.; Long, Cynthia R.; Kawchuk, Gregory N.; Pickar, Joel G.

2013-01-01

OBJECTIVE Mechanical characteristics of high velocity low amplitude spinal manipulations (HVLA-SM) can be variable. Sustained changes in peripheral neuronal signaling due to altered load transmission to a sensory receptor’s local mechanical environment are often considered a mechanism contributing to the therapeutic effects of spinal manipulation. The purpose of this study was to determine whether an HVLA-SM’s thrust amplitude or duration altered neural responsiveness of lumbar muscle spindles to either vertebral movement or position. METHODS Anesthetized cats (n=112) received L6 HVLA-SMs delivered to the spinous process. Cats were divided into 6 cohorts depending upon the peak thrust force (25%, 55%, 85% body weight) or thrust displacement (1, 2, 3mm) they received. Cats in each cohort received 8 thrust durations (0–250ms). Afferent discharge from 112 spindles was recorded in response to ramp and hold vertebral movement before and after the manipulation. Changes in mean instantaneous frequency (MIF) during the baseline period preceding the ramps (ΔMIFresting), during ramp movements (ΔMIFmovement), and with the vertebra held in the new position (ΔMIFposition) were compared. RESULTS Thrust duration had a small but statistically significant effect on ΔMIFresting at all six thrust amplitudes compared to control (0ms thrust duration). The lowest amplitude thrust displacement (1mm) increased ΔMIFresting at all thrust durations. For all the other thrust displacements and forces, the direction of change in ΔMIFresting was not consistent and the pattern of change was not systematically related to thrust duration. Regardless of thrust force, displacement, or duration, ΔMIFmovement and ΔMIFposition were not significantly different from control. Conclusion Relatively low amplitude thrust displacements applied during an HVLA-SM produced sustained increases in the resting discharge of paraspinal muscle spindles regardless of the duration over which the thrust was

Muscle spindle feedback directs locomotor recovery and circuit reorganization after spinal cord injury.

PubMed

Takeoka, Aya; Vollenweider, Isabel; Courtine, Grégoire; Arber, Silvia

2014-12-18

Spinal cord injuries alter motor function by disconnecting neural circuits above and below the lesion, rendering sensory inputs a primary source of direct external drive to neuronal networks caudal to the injury. Here, we studied mice lacking functional muscle spindle feedback to determine the role of this sensory channel in gait control and locomotor recovery after spinal cord injury. High-resolution kinematic analysis of intact mutant mice revealed proficient execution in basic locomotor tasks but poor performance in a precision task. After injury, wild-type mice spontaneously recovered basic locomotor function, whereas mice with deficient muscle spindle feedback failed to regain control over the hindlimb on the lesioned side. Virus-mediated tracing demonstrated that mutant mice exhibit defective rearrangements of descending circuits projecting to deprived spinal segments during recovery. Our findings reveal an essential role for muscle spindle feedback in directing basic locomotor recovery and facilitating circuit reorganization after spinal cord injury. Copyright © 2014 Elsevier Inc. All rights reserved.

Group III/IV muscle afferents limit the intramuscular metabolic perturbation during whole body exercise in humans

PubMed Central

Mangum, Tyler S.; Sidhu, Simranjit K.; Weavil, Joshua C.; Hureau, Thomas J.; Jessop, Jacob E.; Bledsoe, Amber D.; Richardson, Russell S.; Amann, Markus

2016-01-01

Key points The purpose of this study was to determine the role of group III/IV muscle afferents in limiting the endurance exercise‐induced metabolic perturbation assayed in muscle biopsy samples taken from locomotor muscle.Lumbar intrathecal fentanyl was used to attenuate the central projection of μ‐opioid receptor‐sensitive locomotor muscle afferents during a 5 km cycling time trial.The findings suggest that the central projection of group III/IV muscle afferent feedback constrains voluntary neural ‘drive’ to working locomotor muscle and limits the exercise‐induced intramuscular metabolic perturbation.Therefore, the CNS might regulate the degree of metabolic perturbation within locomotor muscle and thereby limit peripheral fatigue. It appears that the group III/IV muscle afferents are an important neural link in this regulatory mechanism, which probably serves to protect locomotor muscle from the potentially severe functional impairment as a consequence of severe intramuscular metabolic disturbance. Abstract To investigate the role of metabo‐ and mechanosensitive group III/IV muscle afferents in limiting the intramuscular metabolic perturbation during whole body endurance exercise, eight subjects performed 5 km cycling time trials under control conditions (CTRL) and with lumbar intrathecal fentanyl impairing lower limb muscle afferent feedback (FENT). Vastus lateralis muscle biopsies were obtained before and immediately after exercise. Motoneuronal output was estimated through vastus lateralis surface electromyography (EMG). Exercise‐induced changes in intramuscular metabolites were determined using liquid and gas chromatography‐mass spectrometry. Quadriceps fatigue was quantified by pre‐ to post‐exercise changes in potentiated quadriceps twitch torque (ΔQTsingle) evoked by electrical femoral nerve stimulation. Although motoneuronal output was 21 ± 12% higher during FENT compared to CTRL (P < 0.05), time to complete the time trial

Jaw Dysfunction Is Associated with Neck Disability and Muscle Tenderness in Subjects with and without Chronic Temporomandibular Disorders

PubMed Central

Silveira, A.; Gadotti, I. C.; Armijo-Olivo, S.; Biasotto-Gonzalez, D. A.; Magee, D.

2015-01-01

Purpose. Tender points in the neck are common in patients with temporomandibular disorders (TMD). However, the correlation among neck disability, jaw dysfunction, and muscle tenderness in subjects with TMD still needs further investigation. This study investigated the correlation among neck disability, jaw dysfunction, and muscle tenderness in subjects with and without chronic TMD. Participants. Forty females between 19 and 49 years old were included in this study. There were 20 healthy controls and 20 subjects who had chronic TMD and neck disability. Methods. Subjects completed the neck disability index and the limitations of daily functions in TMD questionnaires. Tenderness of the masticatory and cervical muscles was measured using an algometer. Results. The correlation between jaw disability and neck disability was significantly high (r = 0.915, P < 0.05). The correlation between level of muscle tenderness in the masticatory and cervical muscles with jaw dysfunction and neck disability showed fair to moderate correlations (r = 0.32–0.65). Conclusion. High levels of muscle tenderness in upper trapezius and temporalis muscles correlated with high levels of jaw and neck dysfunction. Moreover, high levels of neck disability correlated with high levels of jaw disability. These findings emphasize the importance of considering the neck and its structures when evaluating and treating patients with TMD. PMID:25883963

Jaw dysfunction is associated with neck disability and muscle tenderness in subjects with and without chronic temporomandibular disorders.

PubMed

Silveira, A; Gadotti, I C; Armijo-Olivo, S; Biasotto-Gonzalez, D A; Magee, D

2015-01-01

Tender points in the neck are common in patients with temporomandibular disorders (TMD). However, the correlation among neck disability, jaw dysfunction, and muscle tenderness in subjects with TMD still needs further investigation. This study investigated the correlation among neck disability, jaw dysfunction, and muscle tenderness in subjects with and without chronic TMD. Participants. Forty females between 19 and 49 years old were included in this study. There were 20 healthy controls and 20 subjects who had chronic TMD and neck disability. Subjects completed the neck disability index and the limitations of daily functions in TMD questionnaires. Tenderness of the masticatory and cervical muscles was measured using an algometer. The correlation between jaw disability and neck disability was significantly high (r = 0.915, P < 0.05). The correlation between level of muscle tenderness in the masticatory and cervical muscles with jaw dysfunction and neck disability showed fair to moderate correlations (r = 0.32-0.65). High levels of muscle tenderness in upper trapezius and temporalis muscles correlated with high levels of jaw and neck dysfunction. Moreover, high levels of neck disability correlated with high levels of jaw disability. These findings emphasize the importance of considering the neck and its structures when evaluating and treating patients with TMD.

Development of the trigeminal motor neurons in parrots: implications for the role of nervous tissue in the evolution of jaw muscle morphology.

PubMed

Tokita, Masayoshi; Nakayama, Tomoki

2014-02-01

Vertebrates have succeeded to inhabit almost every ecological niche due in large part to the anatomical diversification of their jaw complex. As a component of the feeding apparatus, jaw muscles carry a vital role for determining the mode of feeding. Early patterning of the jaw muscles has been attributed to cranial neural crest-derived mesenchyme, however, much remains to be understood about the role of nonneural crest tissues in the evolution and diversification of jaw muscle morphology. In this study, we describe the development of trigeminal motor neurons in a parrot species with the uniquely shaped jaw muscles and compare its developmental pattern to that in the quail with the standard jaw muscles to uncover potential roles of nervous tissue in the evolution of vertebrate jaw muscles. In parrot embryogenesis, the motor axon bundles are detectable within the muscular tissue only after the basic shape of the muscular tissue has been established. This supports the view that nervous tissue does not primarily determine the spatial pattern of jaw muscles. In contrast, the trigeminal motor nucleus, which is composed of somata of neurons that innervate major jaw muscles, of parrot is more developed compared to quail, even in embryonic stage where no remarkable interspecific difference in both jaw muscle morphology and motor nerve branching pattern is recognized. Our data suggest that although nervous tissue may not have a large influence on initial patterning of jaw muscles, it may play an important role in subsequent growth and maintenance of muscular tissue and alterations in cranial nervous tissue development may underlie diversification of jaw muscle morphology. Copyright © 2013 Wiley Periodicals, Inc.

Myoelectric manifestations of jaw elevator muscle fatigue and recovery in healthy and TMD subjects.

PubMed

Castroflorio, T; Falla, D; Tartaglia, G M; Sforza, C; Deregibus, A

2012-09-01

The effects of muscle pain and fatigue on the control of jaw elevator muscles are not well known. Furthermore, the myoelectric manifestations of fatigue and recovery from fatigue in the masticatory muscles are not reported in literature. The main aims of this study were (i) to evaluate the possible use of surface electromyography (sEMG) as an objective measure of fatigue of the jaw elevator muscles, (ii) to compare the myoelectric manifestations of fatigue in the temporalis anterior and masseter muscles bilaterally, (iii) to assess recovery of the investigated muscles after an endurance test and (iv) to compare fatigue and recovery of the jaw elevator muscles in healthy subjects and patients with muscle-related temporomandibular disorders (TMD). The study was performed on twenty healthy volunteers and eighteen patients with muscle-related TMD. An intra-oral compressive-force sensor was used to measure the voluntary contraction forces close to the intercuspal position and to provide visual feedback of submaximal forces to the subject. Surface EMG signals were recorded with linear electrode arrays during isometric contractions at 20%, 40%, 60% and 80% of the maximum voluntary contraction force, during an endurance test and during the recovery phase. The results showed that (i) the slope of the mean power spectral frequency (MNF) and the initial average rectified value (ARV) could be used to monitor fatigue of the jaw elevators, (ii) the temporalis anterior and masseter muscle show the same myoelectric manifestations of fatigue and recovery and (iii) the initial values of MNF and ARV were lower in patients with muscle-related TMD. The assessment of myoelectric manifestations of fatigue in the masticatory muscles may assist in the clinical assessment of TMDs. © 2012 Blackwell Publishing Ltd.

The role of capsaicin-sensitive muscle afferents in fatigue-induced modulation of the monosynaptic reflex in the rat.

PubMed

Pettorossi, V E; Della Torre, G; Bortolami, R; Brunetti, O

1999-03-01

1. The role of group III and IV afferent fibres of the lateral gastrocnemious muscle (LG) in modulating the homonymous monosynaptic reflex was investigated during muscle fatigue in spinalized rats. 2. Muscle fatigue was induced by a series of increasing tetanic electrical stimuli (85 Hz, 600 ms) delivered to the LG muscle nerve. Series consisted of increasing train numbers from 1 to 60. 3. Potentials from the spinal cord LG motor pool and from the ventral root were recorded in response to proprioceptive afferent stimulation and analysed before and during tetanic muscle activations. Both the pre- and postsynaptic waves showed an initial enhancement and, after a '12-train' series, an increasing inhibition. 4. The enhancement of the responses to muscle fatiguing stimulation disappeared after L3-L6 dorsal root section, while a partial reflex inhibition was still present. Conversely, after section of the corresponding ventral root, there was only a reduction in the inhibitory effect. 5. The monosynaptic reflex was also studied in animals in which a large number of group III and IV muscle afferents were eliminated by injecting capsaicin (10 mM) into the LG muscle. As a result of capsaicin treatment, the fatigue-induced inhibition of the pre- and postsynaptic waves disappeared, while the response enhancement remained. 6. We concluded that the monosynaptic reflex inhibition, but not the enhancement, was mediated by those group III and IV muscle afferents that are sensitive to the toxic action of capsaicin. The afferents that are responsible for the response enhancement enter the spinal cord through the dorsal root, while those responsible for the inhibition enter the spinal cord through both the ventral and dorsal roots.

The role of capsaicin-sensitive muscle afferents in fatigue-induced modulation of the monosynaptic reflex in the rat

PubMed Central

Pettorossi, V E; Torre, G Della; Bortolami, R; Brunetti, O

1999-01-01

The role of group III and IV afferent fibres of the lateral gastrocnemious muscle (LG) in modulating the homonymous monosynaptic reflex was investigated during muscle fatigue in spinalized rats. Muscle fatigue was induced by a series of increasing tetanic electrical stimuli (85 Hz, 600 ms) delivered to the LG muscle nerve. Series consisted of increasing train numbers from 1 to 60. Potentials from the spinal cord LG motor pool and from the ventral root were recorded in response to proprioceptive afferent stimulation and analysed before and during tetanic muscle activations. Both the pre- and postsynaptic waves showed an initial enhancement and, after a ‘12-train’ series, an increasing inhibition. The enhancement of the responses to muscle fatiguing stimulation disappeared after L3-L6 dorsal root section, while a partial reflex inhibition was still present. Conversely, after section of the corresponding ventral root, there was only a reduction in the inhibitory effect. The monosynaptic reflex was also studied in animals in which a large number of group III and IV muscle afferents were eliminated by injecting capsaicin (10 mM) into the LG muscle. As a result of capsaicin treatment, the fatigue-induced inhibition of the pre- and postsynaptic waves disappeared, while the response enhancement remained. We concluded that the monosynaptic reflex inhibition, but not the enhancement, was mediated by those group III and IV muscle afferents that are sensitive to the toxic action of capsaicin. The afferents that are responsible for the response enhancement enter the spinal cord through the dorsal root, while those responsible for the inhibition enter the spinal cord through both the ventral and dorsal roots. PMID:10050025

Evaluation of jaw and neck muscle activities while chewing using EMG-EMG transfer function and EMG-EMG coherence function analyses in healthy subjects.

PubMed

Ishii, Tomohiro; Narita, Noriyuki; Endo, Hiroshi

2016-06-01

This study aims to quantitatively clarify the physiological features in rhythmically coordinated jaw and neck muscle EMG activities while chewing gum using EMG-EMG transfer function and EMG-EMG coherence function analyses in 20 healthy subjects. The chewing side masseter muscle EMG signal was used as the reference signal, while the other jaw (non-chewing side masseter muscle, bilateral anterior temporal muscles, and bilateral anterior digastric muscles) and neck muscle (bilateral sternocleidomastoid muscles) EMG signals were used as the examined signals in EMG-EMG transfer function and EMG-EMG coherence function analyses. Chewing-related jaw and neck muscle activities were aggregated in the first peak of the power spectrum in rhythmic chewing. The gain in the peak frequency represented the power relationships between jaw and neck muscle activities during rhythmic chewing. The phase in the peak frequency represented the temporal relationships between the jaw and neck muscle activities, while the non-chewing side neck muscle presented a broad range of distributions across jaw closing and opening phases. Coherence in the peak frequency represented the synergistic features in bilateral jaw closing muscles and chewing side neck muscle activities. The coherence and phase in non-chewing side neck muscle activities exhibited a significant negative correlation. From above, the bilateral coordination between the jaw and neck muscle activities is estimated while chewing when the non-chewing side neck muscle is synchronously activated with the jaw closing muscles, while the unilateral coordination is estimated when the non-chewing side neck muscle is irregularly activated in the jaw opening phase. Thus, the occurrence of bilateral or unilateral coordinated features in the jaw and neck muscle activities may correspond to the phase characteristics in the non-chewing side neck muscle activities during rhythmical chewing. Considering these novel findings in healthy subjects, EMG

Indirect Estimates of Jaw Muscle Tension in Children with Suspected Hypertonia, Children with Suspected Hypotonia, and Matched Controls

ERIC Educational Resources Information Center

Connaghan, Kathryn P.; Moore, Christopher A.

2013-01-01

Purpose: In this study, the authors compared indirect estimates of jaw-muscle tension in children with suspected muscle-tone abnormalities with age- and gender-matched controls. Method: Jaw movement and muscle activation were measured in children (ages 3 years, 11 months, to 10 years) with suspected muscle-tone abnormalities (Down syndrome or…

Evolution of Muscle Activity Patterns Driving Motions of the Jaw and Hyoid during Chewing in Gnathostomes

PubMed Central

Konow, Nicolai; Herrel, Anthony; Ross, Callum F.; Williams, Susan H.; German, Rebecca Z.; Sanford, Christopher P. J.; Gintof, Chris

2011-01-01

Although chewing has been suggested to be a basal gnathostome trait retained in most major vertebrate lineages, it has not been studied broadly and comparatively across vertebrates. To redress this imbalance, we recorded EMG from muscles powering anteroposterior movement of the hyoid, and dorsoventral movement of the mandibular jaw during chewing. We compared muscle activity patterns (MAP) during chewing in jawed vertebrate taxa belonging to unrelated groups of basal bony fishes and artiodactyl mammals. Our aim was to outline the evolution of coordination in MAP. Comparisons of activity in muscles of the jaw and hyoid that power chewing in closely related artiodactyls using cross-correlation analyses identified reorganizations of jaw and hyoid MAP between herbivores and omnivores. EMG data from basal bony fishes revealed a tighter coordination of jaw and hyoid MAP during chewing than seen in artiodactyls. Across this broad phylogenetic range, there have been major structural reorganizations, including a reduction of the bony hyoid suspension, which is robust in fishes, to the acquisition in a mammalian ancestor of a muscle sling suspending the hyoid. These changes appear to be reflected in a shift in chewing MAP that occurred in an unidentified anamniote stem-lineage. This shift matches observations that, when compared with fishes, the pattern of hyoid motion in tetrapods is reversed and also time-shifted relative to the pattern of jaw movement. PMID:21705368

Muscle spindle alterations precede onset of sensorimotor deficits in Charcot-Marie-Tooth type 2E.

PubMed

Villalón, E; Jones, M R; Sibigtroth, C; Zino, S J; Dale, J M; Landayan, D S; Shen, H; Cornelison, D D W; Garcia, M L

2017-02-01

Charcot-Marie-Tooth (CMT) is the most common inherited peripheral neuropathy, affecting approximately 2.8 million people. The CMT leads to distal neuropathy that is characterized by reduced motor nerve conduction velocity, ataxia, muscle atrophy and sensory loss. We generated a mouse model of CMT type 2E (CMT2E) expressing human neurofilament light E396K (hNF-L E396K ), which develops decreased motor nerve conduction velocity, ataxia and muscle atrophy by 4 months of age. Symptomatic hNF-L E396K mice developed phenotypes that were consistent with proprioceptive sensory defects as well as reduced sensitivity to mechanical stimulation, while thermal sensitivity and auditory brainstem responses were unaltered. Progression from presymptomatic to symptomatic included a 50% loss of large diameter sensory axons within the fifth lumbar dorsal root of hNF-L E396K mice. Owing to proprioceptive deficits and loss of large diameter sensory axons, we analyzed muscle spindle morphology in presymptomatic and symptomatic hNF-L E396K and hNF-L control mice. Muscle spindle cross-sectional area and volume were reduced in all hNF-L E396K mice analyzed, suggesting that alterations in muscle spindle morphology occurred prior to the onset of typical CMT pathology. These data suggested that CMT2E pathology initiated in the muscle spindles altering the proprioceptive sensory system. Early sensory pathology in CMT2E could provide a unifying hypothesis for the convergence of pathology observed in CMT. © 2016 John Wiley & Sons Ltd and International Behavioural and Neural Genetics Society.

Cross-bridge kinetics of fast and slow fibres of cat jaw and limb muscles: correlations with myosin subunit composition.

PubMed

Hoh, Joseph F Y; Li, Zhao-Bo; Qin, Han; Hsu, Michael K H; Rossmanith, Gunther H

2007-01-01

Mechanical properties of the jaw-closing muscles of the cat are poorly understood. These muscles are known to differ in myosin and fibre type compositions from limb muscles. This work aims to correlate mechanical properties of single fibres in cat jaw and limb muscles with their myosin subunit compositions. The stiffness minimum frequency, f(min), which reflects isometric cross-bridge kinetics, was measured in Ca(2+)-activated glycerinated fast and slow fibres from cat jaw and limb muscles for temperatures ranging between 15 and 30 degrees C by mechanical perturbation analysis. At 15 degrees C, f(min) was 0.5 Hz for limb-slow fibres, 4-6 Hz for jaw-slow fibres, and 10-13 Hz for limb-fast and jaw-fast fibres. The activation energy for f(min) obtained from the slope of the Arrhenius plot for limb-slow fibres was 30-40% higher than values for the other three types of fibres. SDS-PAGE and western blotting using highly specific antibodies verified that limb-fast fibres contained IIA or IIX myosin heavy chain (MyHC). Jaw-fast fibres expressed masticatory MyHC while both jaw-fast and jaw-slow fibres expressed masticatory myosin light chains (MLCs). The nucleotide sequences of the 3' ends of the slow MyHC cDNAs isolated from cat masseter and soleus cDNA libraries showed identical coding and 3'-untranslated regions, suggesting that jaw-slow and limb-slow fibres express the same slow MyHC gene. We conclude that the isometric cross-bridge cycling kinetics of jaw-fast and limb-fast fibres detected by f(min) are indistinguishable in spite of differences in MyHC and light chain compositions. However, jaw-slow fibres, in which the same slow MyHCs are found in combination with MLCs of the jaw type, show enhanced cross-bridge cycling kinetics and reduced activation energy for cross-bridge detachment.

Loss of neurotrophin-3 from smooth muscle disrupts vagal gastrointestinal afferent signaling and satiation

PubMed Central

Biddinger, Jessica E.; Baquet, Zachary C.; Jones, Kevin R.; McAdams, Jennifer

2013-01-01

A large proportion of vagal afferents are dependent on neurotrophin-3 (NT-3) for survival. NT-3 is expressed in developing gastrointestinal (GI) smooth muscle, a tissue densely innervated by vagal mechanoreceptors, and thus could regulate their survival. We genetically ablated NT-3 from developing GI smooth muscle and examined the pattern of loss of NT-3 expression in the GI tract and whether this loss altered vagal afferent signaling or feeding behavior. Meal-induced c-Fos activation was reduced in the solitary tract nucleus and area postrema in mice with a smooth muscle-specific NT-3 knockout (SM-NT-3KO) compared with controls, suggesting a decrease in vagal afferent signaling. Daily food intake and body weight of SM-NT-3KO mice and controls were similar. Meal pattern analysis revealed that mutants, however, had increases in average and total daily meal duration compared with controls. Mutants maintained normal meal size by decreasing eating rate compared with controls. Although microstructural analysis did not reveal a decrease in the rate of decay of eating in SM-NT-3KO mice, they ate continuously during the 30-min meal, whereas controls terminated feeding after 22 min. This led to a 74% increase in first daily meal size of SM-NT-3KO mice compared with controls. The increases in meal duration and first meal size of SM-NT-3KO mice are consistent with reduced satiation signaling by vagal afferents. This is the first demonstration of a role for GI NT-3 in short-term controls of feeding, most likely involving effects on development of vagal GI afferents that regulate satiation. PMID:24068045

Group III/IV locomotor muscle afferents alter motor cortical and corticospinal excitability and promote central fatigue during cycling exercise

PubMed Central

Sidhu, Simranjit K.; Weavil, Joshua C.; Mangum, Tyler S.; Jessop, Jacob E.; Richardson, Russell S.; Morgan, David E.; Amann, Markus

2017-01-01

Objective To investigate the influence of group III/IV muscle afferents on the development of central fatigue and corticospinal excitability during exercise. Methods Fourteen males performed cycling-exercise both under control-conditions (CTRL) and with lumbar intrathecal fentanyl (FENT) impairing feedback from leg muscle afferents. Transcranial magnetic- and cervicomedullary stimulation was used to monitor cortical versus spinal excitability. Results While fentanyl-blockade during non-fatiguing cycling had no effect on motor-evoked potentials (MEPs), cervicomedullary-evoked motor potentials (CMEPs) were 13 ± 3% higher (P < 0.05), resulting in a decrease in MEP/CMEP (P < 0.05). Although the pre- to post-exercise reduction in resting twitch was greater in FENT vs. CTRL (−53 ± 3% vs. −39 ± 3%; P < 0.01), the reduction in voluntary muscle activation was smaller (−2 ± 2% vs. −10 ± 2%; P < 0.05). Compared to the start of fatiguing exercise, MEPs and CMEPs were unchanged at exhaustion in CTRL. In contrast, MEPs and MEP/CMEP increased 13 ± 3% and 25 ± 6% in FENT (P < 0.05). Conclusion During non-fatiguing exercise, group III/IV muscle afferents disfacilitate, or inhibit, spinal motoneurons and facilitate motor cortical cells. In contrast, during exhaustive exercise, group III/IV muscle afferents disfacilitate/inhibit the motor cortex and promote central fatigue. Significance Group III/IV muscle afferents influence corticospinal excitability and central fatigue during whole-body exercise in humans. PMID:27866119

Group III/IV locomotor muscle afferents alter motor cortical and corticospinal excitability and promote central fatigue during cycling exercise.

PubMed

Sidhu, Simranjit K; Weavil, Joshua C; Mangum, Tyler S; Jessop, Jacob E; Richardson, Russell S; Morgan, David E; Amann, Markus

2017-01-01

To investigate the influence of group III/IV muscle afferents on the development of central fatigue and corticospinal excitability during exercise. Fourteen males performed cycling-exercise both under control-conditions (CTRL) and with lumbar intrathecal fentanyl (FENT) impairing feedback from leg muscle afferents. Transcranial magnetic- and cervicomedullary stimulation was used to monitor cortical versus spinal excitability. While fentanyl-blockade during non-fatiguing cycling had no effect on motor-evoked potentials (MEPs), cervicomedullary-evoked motor potentials (CMEPs) were 13±3% higher (P<0.05), resulting in a decrease in MEP/CMEP (P<0.05). Although the pre- to post-exercise reduction in resting twitch was greater in FENT vs. CTRL (-53±3% vs. -39±3%; P<0.01), the reduction in voluntary muscle activation was smaller (-2±2% vs. -10±2%; P<0.05). Compared to the start of fatiguing exercise, MEPs and CMEPs were unchanged at exhaustion in CTRL. In contrast, MEPs and MEP/CMEP increased 13±3% and 25±6% in FENT (P<0.05). During non-fatiguing exercise, group III/IV muscle afferents disfacilitate, or inhibit, spinal motoneurons and facilitate motor cortical cells. In contrast, during exhaustive exercise, group III/IV muscle afferents disfacilitate/inhibit the motor cortex and promote central fatigue. Group III/IV muscle afferents influence corticospinal excitability and central fatigue during whole-body exercise in humans. Copyright © 2016 International Federation of Clinical Neurophysiology. All rights reserved.

Role of muscle spindle in weightlessness-induced amyotrophia and muscle pain.

PubMed

Ali, Umar; Fan, Xiao-Li; You, Hao-Jun

2009-10-01

To date, the medium and long-term space flight is urgent in need and has become a major task of our manned space flight program. There is no doubt that medium and long-term space flight has serious damaging impact upon human physiological systems. For instance, atrophy of the lower limb anti-gravity muscle can be induced during the space flight. Muscle atrophy significantly affects the flight of astronauts in space. Most importantly, it influences the precise manipulation of the astronauts and their response capacity to emergencies on returning to the atmosphere from space. Muscle atrophy caused by weightlessness may also seriously disrupt the normal life and work of the astronauts during the re-adaptation period. Here we summarize the corresponding research concentrating on weightlessness-induced changes of muscular structure and function. By combining research on muscle pain, which is a common clinical pain disease, we further provide a hypothesis concerning a dynamic feedback model of "weightlessness condition right triple arrow muscular atrophy <--> muscle pain". This may be useful to explore the neural mechanisms underlying the occurrence and development of muscular atrophy and muscle pain, through the key study of muscle spindle, and furthermore provide more effective therapy for clinical treatment.

Partial transformation from fast to slow muscle fibers induced by deafferentation of capsaicin-sensitive muscle afferents.

PubMed

Brunetti, O; Barazzoni, A M; Della Torre, G; Clavenzani, P; Pettorossi, V E; Bortolami, R

1997-11-01

Mechanical and histochemical characteristics of the lateral gastrocnemius (LG) muscle of the rat were examined 21 days after capsaicin injection into the LG muscle. The capsaicin caused a decrease in generation rate of twitch and tetanic tension and an increase in fatigue resistance of LG muscle. The histochemical muscle fiber profile evaluated by myosin adenosine triphosphatase and reduced nicotinamide adenine dinucleotide tetrazolium reductase methods showed an increase of type I and IIC fibers and a decrease of the type IIB in whole muscle, and a decrease of the IIA, IIX fibers in the red part accompanied by their increase in the white part. Therefore the capsaicin treatment, which selectively eliminated fibers belonging to the III and IV groups of muscle afferents, induced muscle fiber transformation from fast contracting fatiguing fibers to slowly contracting nonfatiguing ones.

Relationships among nocturnal jaw muscle activities, decreased esophageal pH, and sleep positions.

PubMed

Miyawaki, Shouichi; Tanimoto, Yuko; Araki, Yoshiko; Katayama, Akira; Imai, Mikako; Takano-Yamamoto, Teruko

2004-11-01

The purpose of this study was to examine the relationships among nocturnal jaw muscle activities, decreased esophageal pH, and sleep positions. Twelve adult volunteers, including 4 bruxism patients, participated in this study. Portable pH monitoring, electromyography of the temporal muscle, and audio-video recordings were conducted during the night in the subjects' homes. Rhythmic masticatory muscle activity (RMMA) episodes were observed most frequently, with single short-burst episodes the second most frequent. The frequencies of RMMA, single short-burst, and clenching episodes were significantly higher during decreased esophageal pH episodes than those during other times. Both the electromyography and the decreased esophageal pH episodes were most frequently observed in the supine position. These results suggest that most jaw muscle activities, ie, RMMA, single short-burst, and clenching episodes, occur in relation to gastroesophageal reflux mainly in the supine position.

Effect of fusimotor stimulation on Ia discharge during shortening of cat soleus muscle at different speeds

PubMed Central

Appenteng, K.; Prochazka, A.; Proske, U.; Wand, P.

1982-01-01

1. In barbiturate-anaesthetized cats, the L7 and S1 dorsal and ventral roots were dissected to isolate functionally single afferents identified as primary endings of soleus muscle spindles, and motor filaments which exerted a fusimotor action on the afferents with limited action on extrafusal muscle. Up to seven filaments, with an action on a given primary ending, could be isolated and each was classified as exerting either a predominantly dynamic or static action. 2. Combined stimulation of these filaments, at rates up to 200 impulses/s could maintain afferent firing during muscle shortenings at speeds up to 200 mm/s. 3. Fusimotor stimulation could also maintain afferent firing at a target frequency of 100 impulses/s during muscle shortenings up to 200 mm/s. The timing, in relation to the onset of shortening, and the rates of fusimotor stimulation were found to be critical in achieving the target frequency. 4. Sinusoidal modulation of the frequency of fusimotor stimulation was used to study the conditions required to achieve constant afferent firing in the face of imposed sinusoidal length changes. 5. For given depths of modulation, the phase advance of fusimotor stimulation needed to produce minimum modulation of afferent firing (best compensation) increased with increasing frequency of the sinusoids. The compensation deteriorated with an increase in the frequency of the sinusoids and a change in the mean muscle lengths, although in some cases it could be restored by adjustments to the depth of modulation of fusimotor rate. This suggests that for movements of varying speeds and amplitudes, settings which are appropriate for shortening at a given velocity and mean muscle length, do not apply if either of these two variables are altered. 6. These findings demonstrate that the fusimotor system is potentially capable of eliciting constant afferent firing as envisaged in the `servo-assistance' hypothesis (Matthews, 1964, 1972; Stein, 1974). This, and the fact that

Reduced Short- and Long-Latency Afferent Inhibition Following Acute Muscle Pain: A Potential Role in the Recovery of Motor Output.

PubMed

Burns, Emma; Chipchase, Lucinda Sian; Schabrun, Siobhan May

2016-02-13

. Corticomotor output is reduced in response to acute muscle pain, yet the mechanisms that underpin this effect remain unclear. Here the authors investigate the effect of acute muscle pain on short-latency afferent inhibition, long-latency afferent inhibition, and long-interval intra-cortical inhibition to determine whether these mechanisms could plausibly contribute to reduced motor output in pain. . Observational same subject pre-post test design. . Neurophysiology research laboratory. . Healthy, right-handed human volunteers (n = 22, 9 male; mean age ± standard deviation, 22.6 ± 7.8 years). . Transcranial magnetic stimulation was used to assess corticomotor output, short-latency afferent inhibition, long-latency afferent inhibition, and long-interval intra-cortical inhibition before, during, immediately after, and 15 minutes after hypertonic saline infusion into right first dorsal interosseous muscle. Pain intensity and quality were recorded using an 11-point numerical rating scale and the McGill Pain Questionnaire. . Compared with baseline, corticomotor output was reduced at all time points (p = 0.001). Short-latency afferent inhibition was reduced immediately after (p = 0.039), and long-latency afferent inhibition 15 minutes after (p = 0.035), the resolution of pain. Long-interval intra-cortical inhibition was unchanged at any time point (p = 0.36). . These findings suggest short- and long-latency afferent inhibition, mechanisms thought to reflect the integration of sensory information with motor output at the cortex, are reduced following acute muscle pain. Although the functional relevance is unclear, the authors hypothesize a reduction in these mechanisms may contribute to the restoration of normal motor output after an episode of acute muscle pain. © 2016 American Academy of Pain Medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Muscle spindles exhibit core lesions and extensive degeneration of intrafusal fibers in the Ryr1{sup I4895T/wt} mouse model of core myopathy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zvaritch, Elena; MacLennan, David H., E-mail: david.maclennan@utoronto.ca

Muscle spindles from the hind limb muscles of adult Ryr1{sup I4895T/wt} (IT/+) mice exhibit severe structural abnormalities. Up to 85% of the spindles are separated from skeletal muscle fascicles by a thick layer of connective tissue. Many intrafusal fibers exhibit degeneration, with Z-line streaming, compaction and collapse of myofibrillar bundles, mitochondrial clumping, nuclear shrinkage and pyknosis. The lesions resemble cores observed in the extrafusal myofibers of this animal model and of core myopathy patients. Spindle abnormalities precede those in extrafusal fibers, indicating that they are a primary pathological feature in this murine Ryr1-related core myopathy. Muscle spindle involvement, if confirmedmore » for human core myopathy patients, would provide an explanation for an array of devastating clinical features characteristic of these diseases and provide novel insights into the pathology of RYR1-related myopathies. - Highlights: • Muscle spindles exhibit structural abnormalities in a mouse model of core myopathy. • Myofibrillar collapse and mitochondrial clumping is observed in intrafusal fibers. • Myofibrillar degeneration follows a pattern similar to core formation in extrafusal myofibers. • Muscle spindle abnormalities are a part of the pathological phenotype in the mouse model of core myopathy. • Direct involvement of muscle spindles in the pathology of human RYR1-related myopathies is proposed.« less

Ontogeny of the Alligator Cartilago Transiliens and Its Significance for Sauropsid Jaw Muscle Evolution

PubMed Central

Tsai, Henry P.; Holliday, Casey M.

2011-01-01

The cartilago transiliens is a fibrocartilaginous structure within the jaw muscles of crocodylians. The cartilago transiliens slides between the pterygoid buttress and coronoid region of the lower jaw and connects two muscles historically identified as m. pseudotemporalis superficialis and m. intramandibularis. However, the position of cartilago transiliens, and its anatomical similarities to tendon organs suggest the structure may be a sesamoid linking a single muscle. Incompressible sesamoids often form inside tendons that wrap around bone. However, such structures rarely ossify in reptiles and have thus far received scant attention. We tested the hypothesis that the cartilago transiliens is a sesamoid developed within in one muscle by investigating its structure in an ontogenetic series of Alligator mississippiensis using dissection, 3D imaging, and polarizing and standard light microscopy. In all animals studied, the cartilago transiliens receives collagen fibers and tendon insertions from its two main muscular attachments. However, whereas collagen fibers were continuous within the cartilaginous nodule of younger animals, such continuity decreased in older animals, where the fibrocartilaginous core grew to displace the fibrous region. Whereas several neighboring muscles attached to the fibrous capsule in older individuals, only two muscles had significant contributions to the structure in young animals. Our results indicate that the cartilago transiliens is likely a sesamoid formed within a single muscle (i.e., m. pseudotemporalis superficialis) as it wraps around the pterygoid buttress. This tendon organ is ubiquitous among fossil crocodyliforms indicating it is a relatively ancient, conserved structure associated with the development of the large pterygoid flanges in this clade. Finally, these findings indicate that similar tendon organs exist among potentially homologous muscle groups in birds and turtles, thus impacting inferences of jaw muscle homology

Asymmetric activation of motor cortex controlling human anterior digastric muscles during speech and target-directed jaw movements.

PubMed

Sowman, Paul F; Flavel, Stanley C; McShane, Christie L; Sakuma, Shigemitsu; Miles, Timothy S; Nordstrom, Michael A

2009-07-01

Like most of the cranial muscles involved in speech, the trigeminally innervated anterior digastric muscles are controlled by descending corticobulbar projections from the primary motor cortex (M1) of each hemisphere. We hypothesized that changes in corticobulbar M1 excitability during speech production would show a hemispheric asymmetry favoring the left side, which is the dominant hemisphere for language processing in most strongly right handed subjects. Fifteen volunteers aged 24.5+/-5.3 (SD) yr participated. All subjects were strongly right handed as reported by questionnaire. A surface electromyograph (EMG) was recorded bilaterally from digastrics and jaw movement detected by an accelerometer attached to a lower incisor. Focal transcranial magnetic stimulation (TMS) was used to assess corticomotor excitability of the digastric representation in M1 of both hemispheres during four tasks: 1) static isometric contraction of digastrics; 2) speaking a single word; 3) visually guided, nonspeech jaw movement that matched the jaw kinematics recorded during task 2; and 4) reciting a sentence. Background EMG was well matched in all tasks and jaw kinematics were similar around the time of the TMS pulse for tasks 2-4. TMS resting thresholds and digastric muscle-evoked potential (MEP) size during isometric contraction did not differ for TMS over left versus right M1. MEPs elicited by TMS over left, but not right M1 increased in size during speech and nonspeech jaw movement compared with isometric contraction. We conclude that left corticobulbar M1 is preferentially engaged for descending control of digastric muscles during speech and the performance of a rapid jaw movement to match a target kinematic profile.

Postural stability and the influence of concurrent muscle activation--Beneficial effects of jaw and fist clenching.

PubMed

Ringhof, Steffen; Leibold, Timo; Hellmann, Daniel; Stein, Thorsten

2015-10-01

Recent studies reported on the potential benefits of submaximum clenching of the jaw on human postural control in upright unperturbed stance. However, it remained unclear whether these effects might also be observed among active controls. The purpose of the present study, therefore, was to comparatively examine the influence of concurrent muscle activation in terms of submaximum clenching of the jaw and submaximum clenching of the fists on postural stability. Posturographic analyses were conducted with 17 healthy young adults on firm and foam surfaces while either clenching the jaw (JAW) or clenching the fists (FIST), whereas habitual standing served as the control condition (CON). Both submaximum tasks were performed at 25% maximum voluntary contraction, assessed, and visualized in real time by means of electromyography. Statistical analyses revealed that center of pressure (COP) displacements were significantly reduced during JAW and FIST, but with no differences between both concurrent clenching activities. Further, a significant increase in COP displacements was observed for the foam as compared to the firm condition. The results showed that concurrent muscle activation significantly improved postural stability compared with habitual standing, and thus emphasize the beneficial effects of jaw and fist clenching for static postural control. It is suggested that concurrent activities contribute to the facilitation of human motor excitability, finally increasing the neural drive to the distal muscles. Future studies should evaluate whether elderly or patients with compromised postural control might benefit from these physiological responses, e.g., in the form of a reduced risk of falling. Copyright © 2015 Elsevier B.V. All rights reserved.

Jaw Dysfunction Related to Pterygoid and Masseter Muscle Dosimetry After Radiation Therapy in Children and Young Adults With Head-and-Neck Sarcomas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krasin, Matthew J., E-mail: matthew.krasin@stjude.org; Wiese, Kristin M.; Spunt, Sheri L.

Purpose: To investigate the relationship between jaw function, patient and treatment variables, and radiation dosimetry of the mandibular muscles and joints in children and young adults receiving radiation for soft-tissue and bone sarcomas. Methods and Materials: Twenty-four pediatric and young adult patients with head-and-neck sarcomas were treated on an institutional review board-approved prospective study of focal radiation therapy for local tumor control. Serial jaw depression measurements were related to radiation dosimetry delivered to the medial and lateral pterygoid muscles, masseter muscles, and temporomandibular joints to generate mathematical models of jaw function. Results: Baseline jaw depression was only influenced by themore » degree of surgical resection. In the first 12 weeks from initiation of radiation, surgical procedures greater than a biopsy, administration of cyclophosphamide containing chemotherapy regimes, and large gross tumor volumes adversely affected jaw depression. Increasing dose to the pterygoid and masseter muscles above 40 Gy predicted loss of jaw function over the full course of follow-up. Conclusions: Clinical and treatment factors are related to initial and subsequent jaw dysfunction. Understanding these complex interactions and the affect of specific radiation doses may help reduce the risk for jaw dysfunction in future children and young adults undergoing radiation therapy for the management of soft-tissue and bone sarcomas.« less

Choice of biomaterials—Do soft occlusal splints influence jaw-muscle activity during sleep? A preliminary report

NASA Astrophysics Data System (ADS)

Arima, Taro; Takeuchi, Tamiyo; Tomonaga, Akio; Yachida, Wataru; Ohata, Noboru; Svensson, Peter

2012-12-01

AimThe choice of biomaterials for occlusal splints may significantly influence biological outcome. In dentistry, hard acrylic occlusal splints (OS) have been shown to have a temporary and inhibitory effect on jaw-muscle activity, such as tooth clenching and grinding during sleep, i.e., sleep bruxism (SB). Traditionally, this inhibitory effect has been explained by changes in the intraoral condition rather than the specific effects of changes in occlusion. The aim of this preliminary study was to investigate the effect of another type of occlusal surface, such as a soft-material OS in addition to a hard-type OS in terms of changes in jaw-muscle activity during sleep. Materials and methodsSeven healthy subjects (mean ± SD, six men and one woman: 28.9 ± 2.7 year old), participated in this study. A soft-material OS (ethylene vinyl acetate copolymer) was fabricated for each subject and the subjects used the OS for five continuous nights. The EMG activity during sleep was compared to baseline (no OS). Furthermore, the EMG activity during the use of a hard-type OS (Michigan-type OS, acrylic resin), and hard-type OS combined with contingent electrical stimulation (CES) was compared to baseline values. Each session was separated by at least two weeks (washout). Jaw-muscle activity during sleep was recorded with single-channel ambulatory devices (GrindCare, MedoTech, Herlev, Denmark) in all sessions for five nights. ResultsJaw-muscle activity during sleep was 46.6 ± 29.8 EMG events/hour at baseline and significantly decreased during the hard-type OS (17.4 ± 10.5, P = 0.007) and the hard-type OS + CES (10.8 ± 7.1, P = 0.002), but not soft-material OS (36.3 ± 24.5, P = 0.055). Interestingly, the soft-material OS (coefficient of variance = 98.6 ± 35.3%) was associated with greater night-to-night variations than baseline (39.0 ± 11.8%) and the hard-type OS + CES (53.3 ± 13.7%, P < 0.013). ConclusionThe present pilot study in small sample showed that a soft

Patterns of primary afferent depolarization of segmental and ascending intraspinal collaterals of single joint afferents in the cat.

PubMed

Rudomin, P; Lomelí, J

2007-01-01

We have examined in the anesthetized cat the threshold changes produced by sensory and supraspinal stimuli on intraspinal collaterals of single afferents from the posterior articular nerve (PAN). Forty-eight fibers were tested in the L3 segment, in or close to Clarke's column, and 70 fibers in the L6-L7 segments within the intermediate zone. Of these, 15 pairs of L3 and L6-L7 collaterals were from the same afferent. Antidromically activated fibers had conduction velocities between 23 and 74 m/s and peripheral thresholds between 1.1 and 4.7 times the threshold of the most excitable fibers (xT), most of them below 3 xT. PAN afferents were strongly depolarized by stimulation of muscle afferents and by cutaneous afferents, as well as by stimulation of the bulbar reticular formation and the midline raphe nuclei. Stimulation of muscle nerves (posterior biceps and semitendinosus, quadriceps) produced a larger PAD (primary afferent depolarization) in the L6-L7 than in the L3 terminations. Group II were more effective than group I muscle afferents. As with group I muscle afferents, the PAD elicited in PAN afferents by stimulation of muscle nerves could be inhibited by conditioning stimulation of cutaneous afferents. Stimulation of the cutaneous sural and superficial peroneal nerves increased the threshold of few terminations (i.e., produced primary afferent hyperpolarization, PAH) and reduced the threshold of many others, particularly of those tested in the L6-L7 segments. Yet, there was a substantial number of terminals where these conditioning stimuli had minor or no effects. Autogenetic stimulation of the PAN with trains of pulses increased the intraspinal threshold in 46% and reduced the threshold in 26% of fibers tested in the L6-L7 segments (no tests were made with trains of pulses on fibers ending in L3). These observations indicate that PAN afferents have a rather small autogenetic PAD, particularly if this is compared with the effects of heterogenetic stimulation

Role of afferent input in load-dependent plasticity of rat muscle

NASA Astrophysics Data System (ADS)

Kawano, F.; Umemoto, S.; Higo, Y.; Kawabe, N.; Wang, X. D.; Lan, Y. B.; Ohira, Y.

We have been studying the role of afferent input in the plasticity of skeletal muscles. The present study was performed to investigate the mechanisms responsible for the deafferentation-related inhibition of the compensatory hypertrophy in rat soleus muscle. Adult male Wistar rats were randomly separated into the control, functionally overloaded (FO), and functionally overloaded + deafferentation (FO+DA) group. The tendons of plantaris and gastrocnemius muscles were transected in the FO rats. The dorsal roots of the spinal cord at the L4-5 segmental levels were additionally transected in the FO+DA rats. The sampling of the soleus was performed 2 weeks after the surgery and ambulation recovery. The single muscle fibers were isolated in low-calcium relaxing solution. Further, the myonuclei or argyrophilic nucleolar organizer regions (AgNORs) were stained. Significant increase of the fiber cross-sectional area (CSA) was seen in the FO, but not in the FO+DA, rats. The myonuclear number in fiber was significantly decreased by FO. Addition of DA to FO further promoted the reduction of myonuclear number. The mean nucleus size and DNA content in single nucleus in all groups were identical. Although a single or double AgNORs were seen in ~90% of myonuclei in the control rats, their distributions were 72 and 76% in the FO and FO+DA rats, respectively (p<0.05). More myonuclei containing 3-5 AgNORs were noted in the FO and FO+DA rats. The mean number of the AgNORs per myonucleus was 1.7 in the control, 2.1 in both FO and FO+DA rats (p<0.05). It was suggested that the FO-related increase of the number of AgNORs may be responsible for the induction of compensatory hypertrophy. It was also indicated that intact afferent input plays an essential role in these phenomena.

Complex impairment of IA muscle proprioceptors following traumatic or neurotoxic injury.

PubMed

Vincent, Jacob A; Nardelli, Paul; Gabriel, Hanna M; Deardorff, Adam S; Cope, Timothy C

2015-08-01

The health of primary sensory afferents supplying muscle has to be a first consideration in assessing deficits in proprioception and related motor functions. Here we discuss the role of a particular proprioceptor, the IA muscle spindle proprioceptor in causing movement disorders in response to either regeneration of a sectioned peripheral nerve or damage from neurotoxic chemotherapy. For each condition, there is a single preferred and widely repeated explanation for disability of movements associated with proprioceptive function. We present a mix of published and preliminary findings from our laboratory, largely from in vivo electrophysiological study of treated rats to demonstrate newly discovered IA afferent defects that seem likely to make important contributions to movement disorders. First, we argue that reconnection of regenerated IA afferents with inappropriate targets, although often repeated as the reason for lost stretch-reflex contraction, is not a complete explanation. We present evidence that despite successful recovery of stretch-evoked sensory signaling, peripherally regenerated IA afferents retract synapses made with motoneurons in the spinal cord. Second, we point to evidence that movement disability suffered by human subjects months after discontinuation of oxaliplatin (OX) chemotherapy for some is not accompanied by peripheral neuropathy, which is the acknowledged primary cause of disability. Our studies of OX-treated rats suggest a novel additional explanation in showing the loss of sustained repetitive firing of IA afferents during static muscle stretch. Newly extended investigation reproduces this effect in normal rats with drugs that block Na(+) channels apparently involved in encoding static IA afferent firing. Overall, these findings highlight multiplicity in IA afferent deficits that must be taken into account in understanding proprioceptive disability, and that present new avenues and possible advantages for developing effective

Inducing any virtual two-dimensional movement in humans by applying muscle tendon vibration.

PubMed

Roll, Jean-Pierre; Albert, Frédéric; Thyrion, Chloé; Ribot-Ciscar, Edith; Bergenheim, Mikael; Mattei, Benjamin

2009-02-01

In humans, tendon vibration evokes illusory sensation of movement. We developed a model mimicking the muscle afferent patterns corresponding to any two-dimensional movement and checked its validity by inducing writing illusory movements through specific sets of muscle vibrators. Three kinds of illusory movements were compared. The first was induced by vibration patterns copying the responses of muscle spindle afferents previously recorded by microneurography during imposed ankle movements. The two others were generated by the model. Sixteen different vibratory patterns were applied to 20 motionless volunteers in the absence of vision. After each vibration sequence, the participants were asked to name the corresponding graphic symbol and then to reproduce the illusory movement perceived. Results showed that the afferent patterns generated by the model were very similar to those recorded microneurographically during actual ankle movements (r=0.82). The model was also very efficient for generating afferent response patterns at the wrist level, if the preferred sensory directions of the wrist muscle groups were first specified. Using recorded and modeled proprioceptive patterns to pilot sets of vibrators placed at the ankle or wrist levels evoked similar illusory movements, which were correctly identified by the participants in three quarters of the trials. Our proprioceptive model, based on neurosensory data recorded in behaving humans, should then be a useful tool in fields of research such as sensorimotor learning, rehabilitation, and virtual reality.

Influence of locomotor muscle afferent inhibition on the ventilatory response to exercise in heart failure.

PubMed

Olson, Thomas P; Joyner, Michael J; Eisenach, John H; Curry, Timothy B; Johnson, Bruce D

2014-02-01

What is the central question of this study? Patients with heart failure often develop ventilatory abnormalities at rest and during exercise, but the mechanisms underlying these abnormalities remain unclear. This study investigated the influence of inhibiting afferent neural feedback from locomotor muscles on the ventilatory response during exercise in heart failure patients. What is the main finding and its importance? Our results suggest that inhibiting afferent feedback from locomotor muscle via intrathecal opioid administration significantly reduces the ventilatory response to exercise in heart failure patients. Patients with heart failure (HF) develop ventilatory abnormalities at rest and during exercise, but the mechanism(s) underlying these abnormalities remain unclear. We examined whether the inhibition of afferent neural feedback from locomotor muscles during exercise reduces exercise ventilation in HF patients. In a randomized, placebo-controlled design, nine HF patients (age, 60 ± 2 years; ejection fraction, 27 ± 2%; New York Heart Association class 2 ± 1) and nine control subjects (age, 63 ± 2 years) underwent constant-work submaximal cycling (65% peak power) with intrathecal fentanyl (impairing the cephalad projection of opioid receptor-sensitive afferents) or sham injection. The hypercapnic ventilatory response was measured to determine whether cephalad migration of fentanyl occurred. There were no differences in hypercapnic ventilatory response within or between groups in either condition. Despite a lack of change in ventilation, tidal volume or respiratory rate, HF patients had a mild increase in arterial carbon dioxide (P(aCO(2)) and a decrease in oxygen (P(aO(2)); P < 0.05 for both) at rest. The control subjects demonstrated no change in P(aCO(2)), P(aO(2)), ventilation, tidal volume or respiratory rate at rest. In response to fentanyl during exercise, HF patients had a reduction in ventilation (63 ± 6 versus 44 ± 3 l min(-1), P < 0.05) due

Bicuculline and strychnine suppress the mesencephalic locomotor region-induced inhibition of group III muscle afferent input to the dorsal horn.

PubMed

Degtyarenko, A M; Kaufman, M P

2003-01-01

We examined the effect of iontophoretic application of bicuculline methiodide and strychnine hydrochloride on the mesencephalic locomotor region (MLR)-induced inhibition of dorsal horn cells in paralyzed cats. The activity of 60 dorsal horn cells was recorded extracellularly in laminae I, II, V-VII of spinal segments L7-S1. Each of the cells was shown to receive group III muscle afferent input as demonstrated by their responses to electrical stimulation of the tibial nerve (mean latency and threshold of activation: 20.1+/-6.4 ms and 15.2+/-1.4 times motor threshold, respectively). Electrical stimulation of the MLR suppressed transmission in group III muscle afferent pathways to dorsal horn cells. Specifically the average number of impulses generated by the dorsal horn neurons in response to a single pulse applied to the tibial nerve was decreased by 78+/-2.8% (n=60) during the MLR stimulation. Iontophoretic application (10-50 nA) of bicuculline and strychnine (5-10 mM) suppressed the MLR-induced inhibition of transmission of group III afferent input to laminae I and II cells by 69+/-5% (n=10) and 29+/-7% (n=7), respectively. Likewise, bicuculline and strychnine suppressed the MLR-induced inhibition of transmission of group III afferent input to lamina V cells by 59+/-13% (n=14) and 39+/-11% (n=10), respectively. Our findings raise the possibility that GABA and glycine release onto dorsal horn neurons in the spinal cord may play an important role in the suppression by central motor command of thin fiber muscle afferent-reflex pathways.

Disturbed jaw behavior in whiplash-associated disorders during rhythmic jaw movements.

PubMed

Häggman-Henrikson, B; Zafar, H; Eriksson, P-O

2002-11-01

As shown previously, "functional jaw movements" are the result of coordinated activation of jaw as well as neck muscles, leading to simultaneous movements in the temporomandibular, atlanto-occipital, and cervical spine joints. In this study, the effect of neck trauma on natural jaw function was evaluated in 12 individuals suffering from whiplash-associated disorders (WAD). Spatiotemporal characteristics of mandibular and concomitant head movements were evaluated for three different modes of rhythmic jaw activities: self-paced continuous maximal jaw-opening/-closing movements, paced continuous maximal jaw-opening/-closing movements at 50 cycles/minute, and unilateral chewing. Compared with healthy subjects, the WAD group showed smaller magnitude and altered coordination pattern (a change in temporal relations) of mandibular and head movements. In conclusion, these results show that neck trauma can derange integrated jaw and neck behavior, and underline the functional coupling between the jaw and head-neck motor systems.

Masticatory myosin unveiled: first determination of contractile parameters of muscle fibers from carnivore jaw muscles.

PubMed

Toniolo, Luana; Cancellara, Pasqua; Maccatrozzo, Lisa; Patruno, Marco; Mascarello, Francesco; Reggiani, Carlo

2008-12-01

Masticatory myosin heavy chain (M MyHC) is a myosin subunit isoform with expression restricted to muscles derived from the first branchial arch, such as jaw-closer muscles, with pronounced interspecies variability. Only sparse information is available on the contractile properties of muscle fibers expressing M MyHC (M fibers). In this study, we characterized M fibers isolated from the jaw-closer muscles (temporalis and masseter) of two species of domestic carnivores, the cat and the dog, compared with fibers expressing slow or fast (2A, 2X, and 2B) isoforms. In each fiber, during maximally calcium-activated contractions at 12 degrees C, we determined isometric-specific tension (P(o)), unloaded shortening velocity (v(o)) with the slack test protocol, and the rate constant of tension redevelopment (K(TR)) after a fast shortening-relengthening cycle. At the end of the mechanical experiment, we identified MyHC isoform composition of each fiber with gel electrophoresis. Electrophoretic migration rate of M MyHC was similar in both species. We found that in both species the kinetic parameters v(o) and K(TR) of M fibers were similar to those of 2A fibers, whereas P(o) values were significantly greater than in any other fiber types. The similarity between 2A and M fibers and the greater tension development of M fibers were confirmed also in mechanical experiments performed at 24 degrees C. Myosin concentration was determined in single fibers and found not different in M fibers compared with slow and fast fibers, suggesting that the higher tension developed by M fibers does not find an explanation in a greater number of force generators. The specific mechanical characteristics of M fibers might be attributed to a diversity in cross-bridge kinetics.

Somatotopic organization of primary afferent perikarya of the guinea-pig extraocular muscles in the trigeminal ganglion: a post-mortem DiI-tracing study.

PubMed

Aigner, M; Robert Lukas, J; Denk, M; Ziya-Ghazvini, F; Kaider, A; Mayr, R

2000-04-01

Apart from the somatotopic organization of the trigeminal ganglion (TG) into the ophthalmic, maxillary and mandibular divisions along the mediolateral axis, there exist further somatotopic organizations within these three divisions. According to literature, the cell organization in the TG and the somatotopy in the brainstem develop together, formed by naturally occurring cell death in the TG. Thus, the somatotopy of the primary afferent trigeminal perikarya is of special interest. The aim of this study was to investigate the location of the primary afferent perikarya of the extraocular muscles (EOMs) in the TG of guinea-pig. The primary afferent perikarya were labeled by post-mortem application of the carbocyanine DiI on the oculomotor nerve branches near their entrance into the single EOMs. The DiI-positive perikarya were found musculo-somatically organized in the ipsilateral ophthalmic part of the TG at a wide range along the dorsoventral axis, expressing an overlap of the representation areas. The primary afferent perikarya of the superior rectus and the superior oblique muscles were mainly localized in the dorsal part of the ganglion while those of the inferior rectus and the inferior oblique muscle mainly in ventral part. The lateral and the medial rectus were predominantly represented in between. An organization along the mediolateral axis of the TG was not observed. Although guinea-pigs lack classical EOM proprioceptors, the somatotopic representation of the extraocular muscle primary afferent perikarya in the TG found in this study is in line with findings in species with well known encapsulated proprioceptors within the EOMs.

Allodynia mediated by C-tactile afferents in human hairy skin.

PubMed

Nagi, Saad S; Rubin, Troy K; Chelvanayagam, David K; Macefield, Vaughan G; Mahns, David A

2011-08-15

We recently showed a contribution of low-threshold cutaneous mechanoreceptors to vibration-evoked changes in the perception of muscle pain. Neutral-touch stimulation (vibration) of the hairy skin during underlying muscle pain evoked an overall increase in pain intensity, i.e. allodynia. This effect appeared to be dependent upon cutaneous afferents, as allodynia was abolished by intradermal anaesthesia. However, it remains unclear whether allodynia results from activation of a single class of cutaneous afferents or the convergence of inputs from multiple classes. Intriguingly, no existing human study has examined the contribution of C-tactile (CT) afferents to allodynia. Detailed psychophysical observations were made in 29 healthy subjects (18 males and 11 females). Sustained muscle pain was induced by infusing hypertonic saline (HS: 5%) into tibialis anterior muscle (TA). Sinusoidal vibration (200 Hz–200 μm) was applied to the hairy skin overlying TA. Pain ratings were recorded using a visual analogue scale (VAS). In order to evaluate the role of myelinated and unmyelinated cutaneous afferents in the expression of vibration-evoked allodynia, compression block of the sciatic nerve, and low-dose intradermal anaesthesia (Xylocaine 0.25%) were used, respectively. In addition, the modulation of muscle pain by gentle brushing (1.0 and 3.0 cm s(−1))--known to excite CT fibres--was examined. Brushing stimuli were applied to the hairy skin with all fibres intact and following the blockade of myelinated afferents. During tonic muscle pain (VAS 4–6), vibration evoked a significant and reproducible increase in muscle pain (allodynia) that persisted following compression of myelinated afferents. During compression block, the sense of vibration was abolished, but the vibration-evoked allodynia persisted. In contrast, selective anaesthesia of unmyelinated cutaneous afferents abolished the allodynia, whereas the percept of vibration remained unaffected. Furthermore

Long-Term Effects of Botulinum Toxin Complex Type A Injection on Mechano- and Metabo-Sensitive Afferent Fibers Originating from Gastrocnemius Muscle

PubMed Central

Caron, Guillaume; Marqueste, Tanguy; Decherchi, Patrick

2015-01-01

The aim of the present study was to investigate long term effects of motor denervation by botulinum toxin complex type A (BoNT/A) from Clostridium Botulinum, on the afferent fibers originating from the gastrocnemius muscle of rats. Animals were divided in 2 experimental groups: 1) untreated animals acting as control and 2) treated animals in which the toxin was injected in the left muscle, the latter being itself divided into 3 subgroups according to their locomotor recovery with the help of a test based on footprint measurements of walking rats: i) no recovery (B0), ii) 50% recovery (B50) and iii) full recovery (B100). Then, muscle properties, metabosensitive afferent fiber responses to potassium chloride (KCl) and lactic acid injections and Electrically-Induced Fatigue (EIF), and mechanosensitive responses to tendon vibrations were measured. At the end of the experiment, rats were killed and the toxin injected muscles were weighted. After toxin injection, we observed a complete paralysis associated to a loss of force to muscle stimulation and a significant muscle atrophy, and a return to baseline when the animals recover. The response to fatigue was only decreased in the B0 group. The responses to KCl injections were only altered in the B100 groups while responses to lactic acid were altered in the 3 injected groups. Finally, our results indicated that neurotoxin altered the biphasic pattern of response of the mechanosensitive fiber to tendon vibrations in the B0 and B50 groups. These results indicated that neurotoxin injection induces muscle afferent activity alterations that persist and even worsen when the muscle has recovered his motor activity. PMID:26485650

Long-Term Effects of Botulinum Toxin Complex Type A Injection on Mechano- and Metabo-Sensitive Afferent Fibers Originating from Gastrocnemius Muscle.

PubMed

Caron, Guillaume; Marqueste, Tanguy; Decherchi, Patrick

2015-01-01

The aim of the present study was to investigate long term effects of motor denervation by botulinum toxin complex type A (BoNT/A) from Clostridium Botulinum, on the afferent fibers originating from the gastrocnemius muscle of rats. Animals were divided in 2 experimental groups: 1) untreated animals acting as control and 2) treated animals in which the toxin was injected in the left muscle, the latter being itself divided into 3 subgroups according to their locomotor recovery with the help of a test based on footprint measurements of walking rats: i) no recovery (B0), ii) 50% recovery (B50) and iii) full recovery (B100). Then, muscle properties, metabosensitive afferent fiber responses to potassium chloride (KCl) and lactic acid injections and Electrically-Induced Fatigue (EIF), and mechanosensitive responses to tendon vibrations were measured. At the end of the experiment, rats were killed and the toxin injected muscles were weighted. After toxin injection, we observed a complete paralysis associated to a loss of force to muscle stimulation and a significant muscle atrophy, and a return to baseline when the animals recover. The response to fatigue was only decreased in the B0 group. The responses to KCl injections were only altered in the B100 groups while responses to lactic acid were altered in the 3 injected groups. Finally, our results indicated that neurotoxin altered the biphasic pattern of response of the mechanosensitive fiber to tendon vibrations in the B0 and B50 groups. These results indicated that neurotoxin injection induces muscle afferent activity alterations that persist and even worsen when the muscle has recovered his motor activity.

Identifying the role of group III/IV muscle afferents in the carotid baroreflex control of mean arterial pressure and heart rate during exercise.

PubMed

Hureau, Thomas J; Weavil, Joshua C; Thurston, Taylor S; Broxterman, Ryan M; Nelson, Ashley D; Bledsoe, Amber D; Jessop, Jacob E; Richardson, Russell S; Wray, D Walter; Amann, Markus

2018-04-15

We investigated the contribution of group III/IV muscle afferents to carotid baroreflex resetting during electrically evoked (no central command) and voluntary (requiring central command) isometric knee extension exercise. Lumbar intrathecal fentanyl was used to attenuate the central projection of μ-opioid receptor-sensitive group III/IV leg muscle afferent feedback. Spontaneous carotid baroreflex control was assessed by loading and unloading the carotid baroreceptors with a variable pressure neck chamber. Group III/IV muscle afferents did not influence spontaneous carotid baroreflex responsiveness at rest or during exercise. Afferent feedback accounted for at least 50% of the exercise-induced increase in the carotid baroreflex blood pressure and heart rate operating points, adjustments that are critical for an appropriate cardiovascular response to exercise. These findings suggest that group III/IV muscle afferent feedback is, independent of central command, critical for the resetting of the carotid baroreflex blood pressure and heart rate operating points, but not for spontaneous baroreflex responsiveness. This study sought to comprehensively investigate the role of metabolically and mechanically sensitive group III/IV muscle afferents in carotid baroreflex responsiveness and resetting during both electrically evoked (EVO, no central command) and voluntary (VOL, requiring central command) isometric single-leg knee-extension (15% of maximal voluntary contraction; MVC) exercise. Participants (n = 8) were studied under control conditions (CTRL) and following lumbar intrathecal fentanyl injection (FENT) to inhibit μ-opioid receptor-sensitive lower limb muscle afferents. Spontaneous carotid baroreflex control of mean arterial pressure (MAP) and heart rate (HR) were assessed following rapid 5 s pulses of neck pressure (NP, +40 mmHg) or suction (NS, -60 mmHg). Resting MAP (87 ± 10 mmHg) and HR (70 ± 8 bpm) were similar between CTRL and FENT conditions (P�

The neural response properties and cortical organization of a rapidly adapting muscle sensory group response that overlaps with the frequencies that elicit the kinesthetic illusion.

PubMed

Marasco, Paul D; Bourbeau, Dennis J; Shell, Courtney E; Granja-Vazquez, Rafael; Ina, Jason G

2017-01-01

Kinesthesia is the sense of limb movement. It is fundamental to efficient motor control, yet its neurophysiological components remain poorly understood. The contributions of primary muscle spindles and cutaneous afferents to the kinesthetic sense have been well studied; however, potential contributions from muscle sensory group responses that are different than the muscle spindles have not been ruled out. Electrophysiological recordings in peripheral nerves and brains of male Sprague Dawley rats with a degloved forelimb preparation provide evidence of a rapidly adapting muscle sensory group response that overlaps with vibratory inputs known to generate illusionary perceptions of limb movement in humans (kinesthetic illusion). This group was characteristically distinct from type Ia muscle spindle fibers, the receptor historically attributed to limb movement sensation, suggesting that type Ia muscle spindle fibers may not be the sole carrier of kinesthetic information. The sensory-neural structure of muscles is complex and there are a number of possible sources for this response group; with Golgi tendon organs being the most likely candidate. The rapidly adapting muscle sensory group response projected to proprioceptive brain regions, the rodent homolog of cortical area 3a and the second somatosensory area (S2), with similar adaption and frequency response profiles between the brain and peripheral nerves. Their representational organization was muscle-specific (myocentric) and magnified for proximal and multi-articulate limb joints. Projection to proprioceptive brain areas, myocentric representational magnification of muscles prone to movement error, overlap with illusionary vibrational input, and resonant frequencies of volitional motor unit contraction suggest that this group response may be involved with limb movement processing.

The neural response properties and cortical organization of a rapidly adapting muscle sensory group response that overlaps with the frequencies that elicit the kinesthetic illusion

PubMed Central

Marasco, Paul D.; Bourbeau, Dennis J.; Shell, Courtney E.; Granja-Vazquez, Rafael; Ina, Jason G.

2017-01-01

Kinesthesia is the sense of limb movement. It is fundamental to efficient motor control, yet its neurophysiological components remain poorly understood. The contributions of primary muscle spindles and cutaneous afferents to the kinesthetic sense have been well studied; however, potential contributions from muscle sensory group responses that are different than the muscle spindles have not been ruled out. Electrophysiological recordings in peripheral nerves and brains of male Sprague Dawley rats with a degloved forelimb preparation provide evidence of a rapidly adapting muscle sensory group response that overlaps with vibratory inputs known to generate illusionary perceptions of limb movement in humans (kinesthetic illusion). This group was characteristically distinct from type Ia muscle spindle fibers, the receptor historically attributed to limb movement sensation, suggesting that type Ia muscle spindle fibers may not be the sole carrier of kinesthetic information. The sensory-neural structure of muscles is complex and there are a number of possible sources for this response group; with Golgi tendon organs being the most likely candidate. The rapidly adapting muscle sensory group response projected to proprioceptive brain regions, the rodent homolog of cortical area 3a and the second somatosensory area (S2), with similar adaption and frequency response profiles between the brain and peripheral nerves. Their representational organization was muscle-specific (myocentric) and magnified for proximal and multi-articulate limb joints. Projection to proprioceptive brain areas, myocentric representational magnification of muscles prone to movement error, overlap with illusionary vibrational input, and resonant frequencies of volitional motor unit contraction suggest that this group response may be involved with limb movement processing. PMID:29182648

Functional characteristics of the rat jaw muscles: daily muscle activity and fiber type composition.

PubMed

Kawai, Nobuhiko; Sano, Ryota; Korfage, Joannes A M; Nakamura, Saika; Tanaka, Eiji; van Wessel, Tim; Langenbach, Geerling E J; Tanne, Kazuo

2009-12-01

Skeletal muscles have a heterogeneous fiber type composition, which reflects their functional demand. The daily muscle use and the percentage of slow-type fibers have been shown to be positively correlated in skeletal muscles of larger animals but for smaller animals there is no information. The examination of this relationship in adult rats was the purpose of this study. We hypothesized a positive relationship between the percentage of fatigue-resistant fibers in each muscle and its total duration of use per day. Fourteen Wistar strain male rats (410-450 g) were used. A radio-telemetric device was implanted to record muscle activity continuously from the superficial masseter, deep masseter, anterior belly of digastric and anterior temporalis muscles. The degree of daily muscle use was quantified by the total duration of muscle activity per day (duty time) exceeding specified levels of the peak activity (2, 5, 20 and 50%). The fiber type composition of the muscles was examined by the myosin heavy chain content of the fibers by means of immunohistochemical staining. At lower activity levels (exceeding 2 and 5% of the peak activity), the duty time of the anterior belly of digastric muscle was significantly (P < 0.01) longer than those of the other muscles. The anterior belly of digastric muscle also contained the highest percentage of slow-type fibers (type I fiber and hybrid fiber co-expressing myosin heavy chain I + IIA) (ca. 11%; P < 0.05). By regression analysis for all four muscles, an inter-muscular comparison showed a positive relationship between the duty time (exceeding 50% of the peak activity) and the percentage of type IIX fibers (P < 0.05), which demonstrate intermediate physiological properties relative to type IIA and IIB fibers. For the jaw muscles of adult male rats, the variations of fiber type composition and muscle use suggest that the muscle containing the largest amounts of slow-type fibers (the anterior belly of digastric muscle) is mainly

Jaw muscle development as evidence for embryonic repatterning in direct-developing frogs.

PubMed Central

Hanken, J; Klymkowsky, M W; Alley, K E; Jennings, D H

1997-01-01

The Puerto Rican direct-developing frog Eleutherodactylus coqui (Leptodactylidae) displays a novel mode of jaw muscle development for anuran amphibians. Unlike metamorphosing species, several larval-specific features never form in E. coqui; embryonic muscle primordia initially assume an abbreviated, mid-metamorphic configuration that is soon remodelled to form the adult morphology before hatching. Also lacking are both the distinct population of larval myofibres and the conspicuous, larval-to-adult myofibre turnover that are characteristic of muscle development in metamorphosing species. These modifications are part of a comprehensive alteration in embryonic cranial patterning that has accompanied life history evolution in this highly speciose lineage. Embryonic 'repatterning' in Eleutherodactylus may reflect underlying developmental mechanisms that mediate the integrated evolution of complex structures. Such mechanisms may also facilitate, in organisms with a primitively complex life cycle, the evolutionary dissociation of embryonic, larval, and adult features. PMID:9332017

Fiber type-specific afferent nerve activity induced by transient contractions of rat bladder smooth muscle in pathological states

PubMed Central

Kuga, Nahoko; Tanioka, Asao; Hagihara, Koichiro; Kawai, Tomoyuki

2017-01-01

Bladder smooth muscle shows spontaneous phasic contractions, which undergo a variety of abnormal changes depending on pathological conditions. How abnormal contractions affect the activity of bladder afferent nerves remains to be fully tested. In this study, we examined the relationship between transient increases in bladder pressure, representing transient contraction of bladder smooth muscle, and spiking patterns of bladder afferent fibers of the L6 dorsal root, in rat pathological models. All recordings were performed at a bladder pressure of approximately 10 cmH2O by maintaining the degree of bladder filling. In the cyclophosphamide-induced model, both Aδ and C fibers showed increased sensitivity to transient bladder pressure increases. In the prostaglandin E2-induced model, Aδ fibers, but not C fibers, specifically showed overexcitation that was time-locked with transient bladder pressure increases. These fiber type-specific changes in nerve spike patterns may underlie the symptoms of urinary bladder diseases. PMID:29267380

Homology of the jaw muscles in lizards and snakes-a solution from a comparative gnathostome approach.

PubMed

Johnston, Peter

2014-03-01

Homology or shared evolutionary origin of jaw adductor muscles in lizards and snakes has been difficult to establish, although snakes clearly arose within the lizard radiation. Lizards typically have temporal adductors layered lateral to medial, and in snakes the muscles are arranged in a rostral to caudal pattern. Recent work has suggested that the jaw adductor group in gnathostomes is arranged as a folded sheet; when this theory is applied to snakes, homology with lizard morphology can be seen. This conclusion revisits the work of S.B. McDowell, J Herpetol 1986; 20:353-407, who proposed that homology involves identity of m. levator anguli oris and the loss of m. adductor mandibulae externus profundus, at least in "advanced" (colubroid) snakes. Here I advance the folded sheet hypothesis across the whole snake tree using new and literature data, and provide a solution to this homology problem. Copyright © 2014 Wiley Periodicals, Inc.

Can short-term oral fine motor training affect precision of task performance and induce cortical plasticity of the jaw muscles?

PubMed

Zhang, Hong; Kumar, Abhishek; Kothari, Mohit; Luo, Xiaoping; Trulsson, Mats; Svensson, Krister G; Svensson, Peter

2016-07-01

The aim was to test the hypothesis that short-term oral sensorimotor training of the jaw muscles would increase the precision of task performance and induce neuroplastic changes in the corticomotor pathways, related to the masseter muscle. Fifteen healthy volunteers performed six series with ten trials of an oral sensorimotor task. The task was to manipulate and position a spherical chocolate candy in between the anterior teeth and split it into two equal halves. The precision of the task performance was evaluated by comparing the ratio between the two split halves. A series of "hold-and-split" tasks was also performed before and after the training. The hold force and split force along with the electromyographic (EMG) activity of jaw muscles were recorded. Motor-evoked potentials and cortical motor maps of the right masseter muscle were evoked by transcranial magnetic stimulation. There was a significant effect of series on the precision of the task performance during the short-term oral sensorimotor training (P < 0.002). The hold force during the "hold-and-split" task was significantly lower after training than before the short-term training (P = 0.011). However, there was no change in the split force and the EMG activity of the jaw muscles before and after the training. Further, there was a significant increase in the amplitude of the motor-evoked potentials (P < 0.016) and in the motor cortex map areas (P = 0.033), after the short-term oral sensorimotor training. Therefore, short-term oral sensorimotor task training increased the precision of task performance and induced signs of neuroplastic changes in the corticomotor pathways, related to the masseter muscle.

Cerebro-afferent vessel and pupillary basal diameter variation induced by stomatognathic trigeminal proprioception: a case report.

PubMed

De Cicco, Vincenzo

2012-09-03

A patient affected by asymmetric hemodynamics of cerebro-afferent vessels underwent duplex color scanner investigations in occlusal proprioceptive un- and rebalance conditions. Pupillometric video-oculographic examinations were performed in order to spot connected trigeminal proprioceptive motor patterns able to interfere on sympathetic autonomic activity. The aim of this case report is to verify if involuntary jaw closing during swallowing, executed in unbalance and rebalance myoelectric activity, would be able to modify cerebral hemodynamics. A 56-year-old Caucasian Italian woman affected by asymmetric blood flow of cerebro-afferent vessels underwent an electromyographic investigation of her occlusal muscles in order to assess their occlusal functional balance. The extreme asymmetry of myoelectric activity in dental occlusion evidenced by electromyographic values suggested the rebalancing of the functions of occlusal muscles through concurrent transcutaneous stimulation of the trigeminal nerve supra- and submandibular motor branches. The above-mentioned method allowed the detection of a symmetric craniomandibular muscular relation that can be kept constant through the use of a cusp bite modeled on the inferior dental arch: called orthotic-syntropic bite for its peculiar use of electrostimulation. A few days later, the patient underwent a duplex color scanner investigation and pupillometric video-oculographic examinations in occlusal unbalance and rebalance conditions. A comparative data analysis showed that an unbalanced dental occlusal function may represent an interferential pattern on cerebral hemodynamics velocity and pupillometric evaluations have proved useful both in the analysis of locus coeruleus functional modalities and as a diagnostic tool in the assessment of pathologies involving locus coeruleus and autonomic systems. The inclusion of myoelectric masseter examinations can be useful in patients with asymmetric hemodynamics of cerebro-afferent

Vagal Afferent Innervation of the Lower Esophageal Sphincter

PubMed Central

Powley, Terry L.; Baronowsky, Elizabeth A.; Gilbert, Jared M.; Hudson, Cherie N.; Martin, Felecia N.; Mason, Jacqueline K.; McAdams, Jennifer L.; Phillips, Robert J.

2013-01-01

To supply a fuller morphological characterization of the vagal afferents innervating the lower esophageal sphincter (LES), specifically to label vagal terminals in the tissues forming the LES in the gastroesophageal junction, the present experiment employed injections of dextran biotin into the nodose ganglia of rats. Four types of vagal afferents innervated the LES. Clasp and sling muscle fibers were directly and prominently innervated by intramuscular arrays (IMAs). Individual IMA terminals subtended about 16° of arc of the esophageal circumference, and, collectively, the terminal fields were distributed within the muscle ring to establish a 360° annulus of mechanoreceptors in the sphincter wall. 3D morphometry of the terminals established that, compared to sling muscle IMAs, clasp muscle IMAs had more extensive arbors and larger receptive fields. In addition, at the cardia, local myenteric ganglia between smooth muscle sheets and striated muscle bundles were innervated by intraganglionic laminar endings (IGLEs), in a pattern similar to the innervation of the myenteric plexus throughout the stomach and esophagus. Finally, as previously described, the principle bundle of sling muscle fibers that links LES sphincter tissue to the antropyloric region of the lesser curvature was innervated by exceptionally long IMAs as well as by unique web ending specializations at the distal attachment of the bundle. Overall, the specialized varieties of densely distributed vagal afferents innervating the LES underscore the conclusion that these sensory projections are critically involved in generating LES reflexes and may be promising targets for managing esophageal dysfunctions. PMID:23583280

Cooling improves the writing performance of patients with writer's cramp.

PubMed

Pohl, Christoph; Happe, Jörg; Klockgether, Thomas

2002-11-01

Cooling of hand and forearm muscles by immersion in 15 degrees C cold water for 5 minutes improved the writing performance of patients with writer's cramp. Since abnormal processing of muscle spindle afferent discharges contributes to the pathology of writer's cramp, this effect might result from a reduction in muscle spindle activity by lowering muscle temperature. Cooling is a simple, cheap, and safe procedure, providing temporary relief for patients with writer's cramp. Copyright 2002 Movement Disorder Society

An electromyographic study of aspects of 'deprogramming' of human jaw muscles.

PubMed

Donegan, S J; Carr, A B; Christensen, L V; Ziebert, G J

1990-11-01

Surface electromyograms from the right and left masseter and anterior temporalis muscles were used to detect peripheral correlates of deprogramming, also known as programming and reprogramming, of jaw elevator muscles. Putative deprogramming was attempted through the clinically recommended use of a leaf gauge, placed for 15 min between the maxillary and mandibular anterior teeth and disoccluding the posterior teeth by about 2 mm. Studied contractile activities were those of postural activity (subconscious, semi-isometric, minimal activity) and intercuspal teeth clenching (conscious, isometric, maximal activity). Use of the leaf gauge did not affect normalized postural activity (about 4%), the duration (about 900 ms) and static work efforts of clenching (about 1200 microV.s), the time to peak mean voltage of clenching (about 400 ms), and the peak mean voltage of clenching (about 300 microV). Activity and asymmetry indices showed that the studied motor innervation patterns were not changed by the leaf gauge.

Role of afferent input and mechanical load for size regulation of rat soleus muscle

NASA Astrophysics Data System (ADS)

Kawano, Fuminori; Matsuka, Yoshikazu; Oke, Yoshihiko; Higo, Yoko; Terada, Masahiro; Umemoto, Shiori; Kawabe, Naoko; Wang, Xiao Dong; Shinoda, Yo; Lan, Yong Bo; Fukuda, Hiroyuki; Ohmi, Shinobu; Ohira, Yoshinobu

2005-08-01

Effects of deafferentation on the phosphorylation of ribosomal protein S6 (S6), 27 kDa heat shock protein (HSP27) and extracellular signal-regulated kinase (ERK) 1/2 were studied in rat soleus muscle. Adult male Wistar rats were randomly separated into the pre- and post- experimental control, functionally overloaded (FO), sham-operated, deafferentated (DA), FO+DA, and hindlimb-unloaded (U) groups. The distal tendons of left plantaris and gastrocnemius muscles were transected in the FO rats. The left dorsal roots of the spinal cord at the L4-5 segmental levels were transected in the DA rats. The rats in U were tail-suspended. The sampling of the soleus muscle was performed 2 weeks after the treatments shown above. The cytoplasmic fraction of the soleus muscle homogenate was used for the quantitative analyses of the phosphorylation levels of S6, HSP27, and ERK 1/2. The phosphorylation levels of these proteins were up-regulated by FO. On the contrary, the phosphorylation of all of these proteins was down-regulated by U and DA. Further, the FO-related increase of the protein phosphorylation was inhibited by additional treatment with DA. These results indicated that the afferent feedback plays crucial roles in the intramuscular regulation of the soleus muscle mass.

Tonic Investigation Concept of Cervico-vestibular Muscle Afferents

PubMed Central

Dorn, Linda Josephine; Lappat, Annabelle; Neuhuber, Winfried; Scherer, Hans; Olze, Heidi; Hölzl, Matthias

2016-01-01

Introduction Interdisciplinary research has contributed greatly to an improved understanding of the vestibular system. To date, however, very little research has focused on the vestibular system's somatosensory afferents. To ensure the diagnostic quality of vestibular somatosensory afferent data, especially the extra cranial afferents, stimulation of the vestibular balance system has to be precluded. Objective Sophisticated movements require intra- and extra cranial vestibular receptors. The study's objective is to evaluate an investigation concept for cervico-vestibular afferents with respect to clinical feasibility. Methods A dedicated chair was constructed, permitting three-dimensional trunk excursions, during which the volunteer's head remains fixed. Whether or not a cervicotonic provocation nystagmus (c-PN) can be induced with static trunk excursion is to be evaluated and if this can be influenced by cervical monophasic transcutaneous electrical nerve stimulation (c-TENS) with a randomized test group. 3D-video-oculography (VOG) was used to record any change in cervico-ocular examination parameters. The occurring nystagmuses were evaluated visually due to the small caliber of nystagmus amplitudes in healthy volunteers. Results The results demonstrate: no influence of placebo-controlled c-TENS on the spontaneous nystagmus; a significant increase of the vertical nystagmus on the 3D-trunk-excursion chair in static trunk flexion with cervical provocation in all young healthy volunteers (n = 49); and a significant difference between vertical and horizontal nystagmuses during static trunk excursion after placebo-controlled c-TENS, except for the horizontal nystagmus during trunk torsion. Conclusion We hope this cervicotonic investigation concept on the 3D trunk-excursion chair will contribute to new diagnostic and therapeutic perspectives on cervical pathologies in vestibular head-to-trunk alignment. PMID:28050208

Chronic low-frequency stimulation transforms cat masticatory muscle fibers into jaw-slow fibers.

PubMed

Kang, Lucia H D; Hoh, Joseph F Y

2011-09-01

Cat masticatory muscle during regeneration expresses masticatory-specific myofibrillar proteins upon innervation by a fast muscle nerve but acquires the jaw-slow phenotype when innervated by a slow muscle nerve. Here, we test the hypothesis that chronic low-frequency stimulation simulating impulses from the slow nerve can result in masticatory-to-slow fiber-type transformation. In six cats, the temporalis muscle was continuously stimulated directly at 10 Hz for up to 12 weeks using a stimulator affixed to the skull. Stimulated muscles were analyzed by immunohistochemistry using, among others, monoclonal antibodies against masticatory-specific myosin heavy chain (MyHC), myosin binding protein-C, and tropomyosins. Under the electrodes, stimulation induced muscle regeneration, which generated slow fibers. Deep to the electrodes, at two to three weeks, two distinct populations of masticatory fibers began to express slow MyHC: 1) evenly distributed fibers that completely suppressed masticatory-specific proteins but transiently co-expressed fetal MyHCs, and 2) incompletely transformed fibers that express slow and masticatory but not fetal MyHCs. SDS-PAGE confirmed de novo expression of slow MyHC and β-tropomyosin in the stimulated muscles. We conclude that chronic low-frequency stimulation induces masticatory-to-slow fiber-type conversion. The two populations of transforming masticatory fibers may differ in their mode of activation or lineage of their myogenic cells.

Effects of prolonged vibration to vastus intermedius muscle on force steadiness of knee extensor muscles during isometric force-matching task.

PubMed

Saito, Akira; Ando, Ryosuke; Akima, Hiroshi

2016-12-01

Afferent inputs from Ia fibers in muscle spindles are essential for the control of force and prolonged vibration has been applied to muscle-tendon units to manipulate the synaptic input from Ia afferents onto α-motor neurons. The vastus intermedius (VI) reportedly provides the highest contribution to the low-level knee extension torque among the individual synergists of quadriceps femoris (QF). The purpose of the present study was to examine the effect of prolonged vibration to the VI on force steadiness of the QF. Nine healthy men (25.1±4.3years) performed submaximal force-matching task of isometric knee extension for 15s before and after mechanical vibration to the superficial region of VI for 30min. Target forces were 2.5%, 10%, and 30% of maximal voluntary contraction (MVC), and force steadiness was determined by the coefficient of variation (CV) of force. After the prolonged VI vibration, the CV of force at 2.5%MVC was significantly increased, but CVs at 10% and 30%MVCs were not significantly changed. The present study concluded that application of prolonged vibration to the VI increased force fluctuations of the QF during a very low-level force-matching task. Copyright © 2016 Elsevier Ltd. All rights reserved.

Proteomics and immunohistochemistry identify the expression of α-cardiac myosin heavy chain in the jaw-closing muscles of sooty mangabeys (order Primates).

PubMed

Wall, Christine E; Holmes, Megan; Soderblom, Erik J; Taylor, Andrea B

2018-07-01

The jaw-closing muscles of humans and nonprimate mammals express alpha-cardiac fibers but MyHC α-cardiac has not been identified in the jaw adductors of nonhuman primates. We determined whether MyHC α-cardiac is expressed in the superficial masseter and temporalis muscles of the sooty mangabey (Cercocebus atys), an African Old World monkey that specializes on hard seeds. LC-MS/MS based proteomics was used to identify the presence of MyHC Iα. Immunohistochemistry was used to analyze the composition and distribution of fiber types in the superficial masseter and temporalis muscles of eight C. atys. Serial sections were stained against MyHC α-cardiac (MYH6), as well as MyHC-1 (NOQ7.5.4D), MyHC-2 (MY-32), and MyHC-M (2F4). Proteomics analysis identified the presence of Myosin-6 (MyHC α-cardiac) in both heart atrium and superficial masseter. MyHC α-cardiac was expressed in abundance in the superficial masseter and temporalis muscles of all eight individuals and hybrid fibers were common. The identification of MyHC α-cardiac in the jaw adductors of sooty mangabeys is a novel finding for nonhuman primates. The abundance of MyHC α-cardiac indicates a fatigue-resistant fiber population characterized by intermediate speed of contraction between pure MyHC-1 and MyHC-2 isoforms. We suggest that α-cardiac fibers may be advantageous to sooty mangabeys, whose feeding behavior includes frequent crushing of relatively large, hard seeds during the power stroke of ingestion. Additional studies comparing jaw-adductor fiber phenotype of hard-object feeding primates and other mammals are needed to explore this relationship further. Copyright © 2018 Elsevier Ltd. All rights reserved.

Heterogeneous Origins of Human Sleep Spindles in Different Cortical Layers.

PubMed

Hagler, Donald J; Ulbert, István; Wittner, Lucia; Erőss, Loránd; Madsen, Joseph R; Devinsky, Orrin; Doyle, Werner; Fabó, Dániel; Cash, Sydney S; Halgren, Eric

2018-03-21

Sleep spindles are a cardinal feature in human NREM sleep and may be important for memory consolidation. We studied the intracortical organization of spindles in men and women by recording spontaneous sleep spindles from different cortical layers using linear microelectrode arrays. Two patterns of spindle generation were identified using visual inspection, and confirmed with factor analysis. Spindles (10-16 Hz) were largest and most common in upper and middle channels, with limited involvement of deep channels. Many spindles were observed in only upper or only middle channels, but approximately half occurred in both. In spindles involving both middle and upper channels, the spindle envelope onset in middle channels led upper by ∼25-50 ms on average. The phase relationship between spindle waves in upper and middle channels varied dynamically within spindle epochs, and across individuals. Current source density analysis demonstrated that upper and middle channel spindles were both generated by an excitatory supragranular current sink while an additional deep source was present for middle channel spindles only. Only middle channel spindles were accompanied by deep low (25-50 Hz) and high (70-170 Hz) gamma activity. These results suggest that upper channel spindles are generated by supragranular pyramids, and middle channel by infragranular. Possibly, middle channel spindles are generated by core thalamocortical afferents, and upper channel by matrix. The concurrence of these patterns could reflect engagement of cortical circuits in the integration of more focal (core) and distributed (matrix) aspects of memory. These results demonstrate that at least two distinct intracortical systems generate human sleep spindles. SIGNIFICANCE STATEMENT Bursts of ∼14 Hz oscillations, lasting ∼1 s, have been recognized for over 80 years as cardinal features of mammalian sleep. Recent findings suggest that they play a key role in organizing cortical activity during memory

Emergence of gamma motor activity in an artificial neural network model of the corticospinal system.

PubMed

Grandjean, Bernard; Maier, Marc A

2017-02-01

Muscle spindle discharge during active movement is a function of mechanical and neural parameters. Muscle length changes (and their derivatives) represent its primary mechanical, fusimotor drive its neural component. However, neither the action nor the function of fusimotor and in particular of γ-drive, have been clearly established, since γ-motor activity during voluntary, non-locomotor movements remains largely unknown. Here, using a computational approach, we explored whether γ-drive emerges in an artificial neural network model of the corticospinal system linked to a biomechanical antagonist wrist simulator. The wrist simulator included length-sensitive and γ-drive-dependent type Ia and type II muscle spindle activity. Network activity and connectivity were derived by a gradient descent algorithm to generate reciprocal, known target α-motor unit activity during wrist flexion-extension (F/E) movements. Two tasks were simulated: an alternating F/E task and a slow F/E tracking task. Emergence of γ-motor activity in the alternating F/E network was a function of α-motor unit drive: if muscle afferent (together with supraspinal) input was required for driving α-motor units, then γ-drive emerged in the form of α-γ coactivation, as predicted by empirical studies. In the slow F/E tracking network, γ-drive emerged in the form of α-γ dissociation and provided critical, bidirectional muscle afferent activity to the cortical network, containing known bidirectional target units. The model thus demonstrates the complementary aspects of spindle output and hence γ-drive: i) muscle spindle activity as a driving force of α-motor unit activity, and ii) afferent activity providing continuous sensory information, both of which crucially depend on γ-drive.

Anatomy, function, and evolution of jaw and hyobranchial muscles in cryptobranchoid salamander larvae.

PubMed

Kleinteich, Thomas; Herzen, Julia; Beckmann, Felix; Matsui, Masafumi; Haas, Alexander

2014-02-01

Larval salamanders (Lissamphibia: Caudata) are known to be effective suction feeders in their aquatic environments, although they will eventually transform into terrestrial tongue feeding adults during metamorphosis. Early tetrapods may have had a similar biphasic life cycle and this makes larval salamanders a particularly interesting model to study the anatomy, function, development, and evolution of the feeding apparatus in terrestrial vertebrates. Here, we provide a description of the muscles that are involved in the feeding strike in salamander larvae of the Hynobiidae and compare them to larvae of the paedomorphic Cryptobranchidae. We provide a functional and evolutionary interpretation for the observed muscle characters. The cranial muscles in larvae from species of the Hynobiidae and Cryptobranchidae are generally very similar. Most notable are the differences in the presence of the m. hyomandibularis, a muscle that connects the hyobranchial apparatus with the lower jaw. We found this muscle only in Onychodactylus japonicus (Hynobiidae) but not in other hynobiid or cryptobranchid salamanders. Interestingly, the m. hyomandibularis in O. japonicus originates from the ceratobranchial I and not the ceratohyal, and thus exhibits what was previously assumed to be the derived condition. Finally, we applied a biomechanical model to simulate suction feeding in larval salamanders. We provide evidence that a flattened shape of the hyobranchial apparatus in its resting position is beneficial for a fast and successful suction feeding strike. Copyright © 2013 Wiley Periodicals, Inc.

Dynamic Interaction of Spindles and Gamma Activity during Cortical Slow Oscillations and Its Modulation by Subcortical Afferents

PubMed Central

Valencia, Miguel; Artieda, Julio; Bolam, J. Paul; Mena-Segovia, Juan

2013-01-01

Slow oscillations are a hallmark of slow wave sleep. They provide a temporal framework for a variety of phasic events to occur and interact during sleep, including the expression of high-frequency oscillations and the discharge of neurons across the entire brain. Evidence shows that the emergence of distinct high-frequency oscillations during slow oscillations facilitates the communication among brain regions whose activity was correlated during the preceding waking period. While the frequencies of oscillations involved in such interactions have been identified, their dynamics and the correlations between them require further investigation. Here we analyzed the structure and dynamics of these signals in anesthetized rats. We show that spindles and gamma oscillations coexist but have distinct temporal dynamics across the slow oscillation cycle. Furthermore, we observed that spindles and gamma are functionally coupled to the slow oscillations and between each other. Following the activation of ascending pathways from the brainstem by means of a carbachol injection in the pedunculopontine nucleus, we were able to modify the gain in the gamma oscillations that are independent of the spindles while the spindle amplitude was reduced. Furthermore, carbachol produced a decoupling of the gamma oscillations that are dependent on the spindles but with no effect on their amplitude. None of the changes in the high-frequency oscillations affected the onset or shape of the slow oscillations, suggesting that slow oscillations occur independently of the phasic events that coexist with them. Our results provide novel insights into the regulation, dynamics and homeostasis of cortical slow oscillations. PMID:23844020

Group II muscle afferents probably contribute to the medium latency soleus stretch reflex during walking in humans

PubMed Central

Grey, Michael J; Ladouceur, Michel; Andersen, Jacob B; Nielsen, Jens Bo; Sinkjær, Thomas

2001-01-01

The objective of this study was to determine which afferents contribute to the medium latency response of the soleus stretch reflex resulting from an unexpected perturbation during human walking. Fourteen healthy subjects walked on a treadmill at approximately 3.5 km h−1 with the left ankle attached to a portable stretching device. The soleus stretch reflex was elicited by applying small amplitude (∼8 deg) dorsiflexion perturbations 200 ms after heel contact. Short and medium latency responses were observed with latencies of 55 ± 5 and 78 ± 6 ms, respectively. The short latency response was velocity sensitive (P < 0.001), while the medium latency response was not (P = 0.725). Nerve cooling increased the delay of the medium latency component to a greater extent than that of the short latency component (P < 0.005). Ischaemia strongly decreased the short latency component (P = 0.004), whereas the medium latency component was unchanged (P = 0.437). Two hours after the ingestion of tizanidine, an α2-adrenergic receptor agonist known to selectively depress the transmission in the group II afferent pathway, the medium latency reflex was strongly depressed (P = 0.007), whereas the short latency component was unchanged (P = 0.653). An ankle block with lidocaine hydrochloride was performed to suppress the cutaneous afferents of the foot and ankle. Neither the short (P = 0.453) nor medium (P = 0.310) latency reflexes were changed. Our results support the hypothesis that, during walking the medium latency component of the stretch reflex resulting from an unexpected perturbation is contributed to by group II muscle afferents. PMID:11483721

Mucinous breast carcinoma with myoepithelial-like spindle cells.

PubMed

Miyake, Yasuyuki; Hirokawa, Mitsuyoshi; Norimatsu, Yoshiaki; Kanahara, Takuo; Monobe, Yasumasa; Ohno, Setsuyo; Miyamoto, Tomoyuki; Yakushiji, Hiromasa; Sakaguchi, Takuya; Aratake, Yatsuki; Ohno, Eiji

2009-06-01

Appearance of spindle cells has been believed as a benign index of breast cytology. But, we have frequently observed the spindle cells in smears from mucinous carcinoma of the breast. Here, we characterized the biochemical nature of the spindle cells, so as to clarify their identity in cytology. Nineteen cases of breast mucinous carcinoma were used for cytological examination. The spindle cells were located at edges of tumor cell nests and in the backgrounds of cytological specimens. Immunohistological examination revealed that the spindle cells exhibited both immunoreactivity against carcinoembryonic antigen (CEA) and epithelial membrane antigen (EMA). Immunoreactivity against vimentin, cytokeratin, or alpha-smooth muscle actin was, however, not observed. The mode of distribution of biochemical markers suggests that the positive cells for anti-CEA antibody and anti-EMA antibody are tumor cells compressed by mucin, while the vimentin-positive cells are fibroblasts. We assert that the presence of spindle cells can be a characteristic feature of mucinous carcinoma of the breast. Discrimination of the spindle cells in mucinous carcinoma from myoepithelial cells and naked bipolar nuclei in benign lesions was established here. It should facilitate precise diagnosis of breast cancer. (c) 2009 Wiley-Liss, Inc.

Afferent Nerve Regulation of Bladder Function in Health and Disease

PubMed Central

de Groat, William C.; Yoshimura, Naoki

2012-01-01

The afferent innervation of the urinary bladder consists primarily of small myelinated (Aδ) and unmyelinated (C-fiber) axons that respond to chemical and mechanical stimuli. Immunochemical studies indicate that bladder afferent neurons synthesize several putative neurotransmitters, including neuropeptides, glutamic acid, aspartic acid, and nitric oxide. The afferent neurons also express various types of receptors and ion channels, including transient receptor potential channels, purinergic, muscarinic, endothelin, neurotrophic factor, and estrogen receptors. Patch-clamp recordings in dissociated bladder afferent neurons and recordings of bladder afferent nerve activity have revealed that activation of many of these receptors enhances neuronal excitability. Afferent nerves can respond to chemicals present in urine as well as chemicals released in the bladder wall from nerves, smooth muscle, inflammatory cells, and epithelial cells lining the bladder lumen. Pathological conditions alter the chemical and electrical properties of bladder afferent pathways, leading to urinary urgency, increased voiding frequency, nocturia, urinary incontinence, and pain. Neurotrophic factors have been implicated in the pathophysiological mechanisms underlying the sensitization of bladder afferent nerves. Neurotoxins such as capsaicin, resiniferatoxin, and botulinum neurotoxin that target sensory nerves are useful in treating disorders of the lower urinary tract. PMID:19655106

Fibrosarcoma of the jaws: two cases of primary tumors with intraosseous growth.

PubMed

Angiero, Francesca; Rizzuti, Tommaso; Crippa, Rolando; Stefani, Michele

2007-01-01

Fibrosarcoma (FS) is a malignant mesenchymal neoplasm of the fibroblasts that rarely affects the oral cavity. Two cases of primary FS of the jaws with intraosseous growth (2 men, aged 53 and 71 years) are described. Microscopically, in one case the tumor showed an intense proliferation of spindle-shaped cells, varying little in size and shape and arranged in parallel bands, partly crossing each other, with significant mitotic activity and nuclear pleomorphism; the second case was characterized by low cellularity comprising spindle-shaped cells, deposited in a variably fibrous and myxoid stroma. On immunohistochemistry, cells in both cases were strongly immunoreactive for MIB-1 and vimentin, focally positive for CD68, and negative for S-100 protein, pancytokeratin, HMB45, CD34, desmin, smooth muscle actin (SMA) and epithelial membrane antigen (EMA). Based on clinical, histological and immunohistochemical findings, the final diagnosis was FS in the first case, myxofibrosarcoma in the second. Treatment was radical surgery with mandibular reconstruction. After two years, the first patient displayed multiple metastases and died during the third year after the initial diagnosis; the second patient was still alive and doing well five years after treatment. We discuss the differential diagnosis versus other forms of sarcoma, examining the morphological appearance that is frequently very similar, the immunohistochemical expression of MIB-1, vimentin, S-100, CD-34, CD68, EMA, as well as conventional clinicopathological features that may help to distinguish FS from other sarcomas.

The influence of altered working-side occlusal guidance on masticatory muscles and related jaw movement.

PubMed

Belser, U C; Hannam, A G

1985-03-01

The effect of four different occlusal situations (group function, canine guidance, working side occlusal interference, and hyperbalancing occlusal interference) on EMG activity in jaw elevator muscles and related mandibular movement was investigated on 12 subjects. With a computer-based system, EMG and displacement signals were collected simultaneously during specific functional (unilateral chewing) and parafunctional tasks (mandibular gliding movements and various tooth clenching efforts) and analyzed quantitatively. When a naturally acquired group function was temporarily and artificially changed into a dominant canine guidance, a significant general reduction of elevator muscle activity was observed when subjects exerted full isometric tooth-clenching efforts in a lateral mandibular position. The original muscular coordination pattern (relative contraction from muscle to muscle) remained unaltered during this test. With respect to unilateral chewing, no significant alterations in the activity or coordination of the muscles occurred when an artificial canine guidance was introduced. Introduction of a hyperbalancing occlusal contact caused significant alterations in muscle activity and coordination during maximal tooth clenching in a lateral mandibular position. A marked shift of temporal muscle EMG activity toward the side of the interference and unchanged bilateral activity of the two masseter muscles were observed. The results suggest that canine-protected occlusions do not significantly alter muscle activity during mastication but significantly reduce muscle activity during parafunctional clenching. They also suggest that non-working side contacts dramatically alter the distribution of muscle activity during parafunctional clenching, and that this redistribution may affect the nature of reaction forces at the temporomandibular joints.

Successful treatment of open jaw and jaw deviation dystonia with botulinum toxin using a simple intraoral approach.

PubMed

Moscovich, Mariana; Chen, Zhongxing Peng; Rodriguez, Ramon

2015-03-01

Oromandibular dystonia (OMD) is a focal dystonia that involves the mouth, jaw, and/or tongue. It can be classified as idiopathic, tardive dystonia or secondary to other neurological disorders and subdivided into jaw opening, jaw closing, jaw deviation and lip pursing. The muscles involved in jaw opening dystonia are usually the digastrics and lateral pterygoids. It is known that the lateral pterygoids may be approached both internally and externally. The external approach is the most common; however neurologists experienced in treating patients with botulinum toxin can safely and with no extra cost perform the intraoral procedure. We report our experience in the treatment of jaw opening and jaw deviation dystonia using the intraoral injection approach. Eight patients were selected from the University of Florida with a clinical diagnosis of open jaw/jaw deviation dystonia. All of them were injected with onabotulinum toxin A using the internal approach and the clinical global impression scale was applied. The mean age of the patients was 67 (standard deviation [SD] 10.2) years, with a disease duration of 10.2 (SD 7.7) years and the mean distance they traveled to our institution was 448 km (278 miles). After treatment, six patients scored as very much improved in the clinical global impression scale and two patients scored as much improved. Only one patient reported an adverse event of nasal speech following one of the injections that improved after 4 weeks. Botulinum toxin injections for open jaw/jaw deviation dystonia can be safely performed with the intraoral approach without the need of special devices other than electromyography. Copyright © 2014 Elsevier Ltd. All rights reserved.

Neuromorphic meets neuromechanics, part I: the methodology and implementation

NASA Astrophysics Data System (ADS)

Niu, Chuanxin M.; Jalaleddini, Kian; Sohn, Won Joon; Rocamora, John; Sanger, Terence D.; Valero-Cuevas, Francisco J.

2017-04-01

Objective: One goal of neuromorphic engineering is to create ‘realistic’ robotic systems that interact with the physical world by adopting neuromechanical principles from biology. Critical to this is the methodology to implement the spinal circuitry responsible for the behavior of afferented muscles. At its core, muscle afferentation is the closed-loop behavior arising from the interactions among populations of muscle spindle afferents, alpha and gamma motoneurons, and muscle fibers to enable useful behaviors. Approach. We used programmable very- large-scale-circuit (VLSI) hardware to implement simple models of spiking neurons, skeletal muscles, muscle spindle proprioceptors, alpha-motoneuron recruitment, gamma motoneuron control of spindle sensitivity, and the monosynaptic circuitry connecting them. This multi-scale system of populations of spiking neurons emulated the physiological properties of a pair of antagonistic afferented mammalian muscles (each simulated by 1024 alpha- and gamma-motoneurones) acting on a joint via long tendons. Main results. This integrated system was able to maintain a joint angle, and reproduced stretch reflex responses even when driving the nonlinear biomechanics of an actual cadaveric finger. Moreover, this system allowed us to explore numerous values and combinations of gamma-static and gamma-dynamic gains when driving a robotic finger, some of which replicated some human pathological conditions. Lastly, we explored the behavioral consequences of adopting three alternative models of isometric muscle force production. We found that the dynamic responses to rate-coded spike trains produce force ramps that can be very sensitive to tendon elasticity, especially at high force output. Significance. Our methodology produced, to our knowledge, the first example of an autonomous, multi-scale, neuromorphic, neuromechanical system capable of creating realistic reflex behavior in cadaveric fingers. This research platform allows us to explore

Fatigue-related firing of muscle nociceptors reduces voluntary activation of ipsilateral but not contralateral lower limb muscles.

PubMed

Kennedy, David S; Fitzpatrick, Siobhan C; Gandevia, Simon C; Taylor, Janet L

2015-02-15

During fatiguing upper limb exercise, maintained firing of group III/IV muscle afferents can limit voluntary drive to muscles within the same limb. It is not known if this effect occurs in the lower limb. We investigated the effects of group III/IV muscle afferent firing from fatigued ipsilateral and contralateral extensor muscles and ipsilateral flexor muscles of the knee on voluntary activation of the knee extensors. In three experiments, we examined voluntary activation of the knee extensors by measuring changes in superimposed twitches evoked by femoral nerve stimulation. Subjects attended on 2 days for each experiment. On one day a sphygmomanometer cuff occluded blood flow of the fatigued muscles to maintain firing of group III/IV muscle afferents. After a 2-min extensor contraction (experiment 1; n = 9), mean voluntary activation was lower with than without maintained ischemia (47 ± 19% vs. 87 ± 8%, respectively; P < 0.001). After a 2-min knee flexor maximal voluntary contraction (MVC) (experiment 2; n = 8), mean voluntary activation was also lower with than without ischemia (59 ± 21% vs. 79 ± 9%; P < 0.01). After the contralateral (left) MVC (experiment 3; n = 8), mean voluntary activation of the right leg was similar with or without ischemia (92 ± 6% vs. 93 ± 4%; P = 0.65). After fatiguing exercise, activity in group III/IV muscle afferents reduces voluntary activation of the fatigued muscle and nonfatigued antagonist muscles in the same leg. However, group III/IV muscle afferents from the fatigued left leg had no effect on the unfatigued right leg. This suggests that any "crossover" of central fatigue in the lower limbs is not mediated by group III/IV muscle afferents. Copyright © 2015 the American Physiological Society.

Evolutionary Trends in the Jaw Adductor Mechanics of Ornithischian Dinosaurs.

PubMed

Nabavizadeh, Ali

2016-03-01

Jaw mechanics in ornithischian dinosaurs have been widely studied for well over a century. Most of these studies, however, use only one or few taxa within a given ornithischian clade as a model for feeding mechanics across the entire clade. In this study, mandibular mechanical advantages among 52 ornithischian genera spanning all subclades are calculated using 2D lever arm methods. These lever arm calculations estimate the effect of jaw shape and difference in adductor muscle line of action on relative bite forces along the jaw. Results show major instances of overlap between taxa in tooth positions at which there was highest mechanical advantage. A relatively low bite force is seen across the tooth row among thyreophorans (e.g., stegosaurs and ankylosaurs), with variation among taxa. A convergent transition occurs from a more evenly distributed bite force along the jaw in basal ornithopods and basal marginocephalians to a strong distal bite force in hadrosaurids and ceratopsids, respectively. Accordingly, adductor muscle vector angles show repeated trends from a mid-range caudodorsal orientation in basal ornithischians to a decrease in vector angles indicating more caudally oriented jaw movements in derived taxa (e.g., derived thyreophorans, basal ornithopods, lambeosaurines, pachycephalosaurs, and derived ceratopsids). Analyses of hypothetical jaw morphologies were also performed, indicating that both the coronoid process and lowered jaw joint increase moment arm length therefore increasing mechanical advantage of the jaw apparatus. Adaptive trends in craniomandibular anatomy show that ornithischians evolved more complex feeding apparatuses within different clades as well as morphological convergences between clades. © 2016 Wiley Periodicals, Inc.

A novel approach using tendon vibration of the human flexor carpi radialis muscle to study spinal reflexes.

PubMed

Tsang, Kenneth; de Bruin, Hubert; Archambeault, Mark

2008-01-01

Although most muscle spindle investigations have used the cat model and invasive measurement techniques, several investigators have used microneurography to record from the Ia and II fibres in humans during tendon vibration. In these studies the muscle spindle primary endings are stimulated using transverse vibration of the tendon at reflex sub-threshold amplitudes. Others have used low amplitude vibration and the stretch evoked M-wave response to determine reflex properties during both agonist and antagonist voluntary contractions. In the past we have developed a PC based instrument that uses Labview and a linear servomotor to study tendon reflex properties by recording stretch evoked M-wave responses from single tendon taps or electrical stimuli to the afferent nerve. In this paper we describe a further development of this system to provide precise vibrations of the tendon up to 65 Hz with amplitudes up to 4 mm. The resultant M-wave train is extracted from background noise via phase coherent subtractive filtering. Test results from vibrating the human distal flexor carpi radialis tendon at 10 and 30 Hz, for relaxed, slight flexion and slight extension, are also presented.

Effects of orthognathic surgery for class III malocclusion on signs and symptoms of temporomandibular disorders and on pressure pain thresholds of the jaw muscles.

PubMed

Farella, M; Michelotti, A; Bocchino, T; Cimino, R; Laino, A; Steenks, M H

2007-07-01

The aim of this longitudinal study was to determine the effects of orthognathic surgery on signs and symptoms of temporomandibular disorders (TMD) and on pressure pain thresholds (PPTs) of the jaw muscles. Fourteen consecutive class III patients undergoing pre-surgical orthodontic treatment were treated by combined Le Fort I osteotomy and bilateral sagittal ramus osteotomy. The clinical examination included the assessment of signs and symptoms of TMD and the assessment of PPTs of the masseter and temporalis muscles. Anamnestic, clinical and algometric data were collected during five sessions over a 1-year period. Seven out of 14 patients presented with disc displacement with reduction at baseline, whereas four patients (two of them were new cases) did so at the end of follow up (p>0.05). None of the patients were diagnosed with myofascial pain of the jaw muscles at the beginning or end of follow up. PPTs of the masseter and temporalis muscles did not change significantly from baseline values throughout the whole study period. The occurrence of signs and symptoms of TMD fluctuates with an unpredictable pattern after orthognathic surgery for class III malocclusions.

Involvement of histaminergic inputs in the jaw-closing reflex arc

PubMed Central

Gemba, Chikako; Nakayama, Kiyomi; Nakamura, Shiro; Mochizuki, Ayako; Inoue, Tomio

2015-01-01

Histamine receptors are densely expressed in the mesencephalic trigeminal nucleus (MesV) and trigeminal motor nucleus. However, little is known about the functional roles of neuronal histamine in controlling oral-motor activity. Thus, using the whole-cell recording technique in brainstem slice preparations from Wistar rats aged between postnatal days 7 and 13, we investigated the effects of histamine on the MesV neurons innervating the masseter muscle spindles and masseter motoneurons (MMNs) that form a reflex arc for the jaw-closing reflex. Bath application of histamine (100 μM) induced membrane depolarization in both MesV neurons and MMNs in the presence of tetrodotoxin, whereas histamine decreased and increased the input resistance in MesV neurons and MMNs, respectively. The effects of histamine on MesV neurons and MMNs were mimicked by an H1 receptor agonist, 2-pyridylethylamine (100 μM). The effects of an H2 receptor agonist, dimaprit (100 μM), on MesV neurons were inconsistent, whereas MMNs were depolarized without changes in the input resistance. An H3 receptor agonist, immethridine (100 μM), also depolarized both MesV neurons and MMNs without changing the input resistance. Histamine reduced the peak amplitude of postsynaptic currents (PSCs) in MMNs evoked by stimulation of the trigeminal motor nerve (5N), which was mimicked by 2-pyridylethylamine but not by dimaprit or immethridine. Moreover, 2-pyridylethylamine increased the failure rate of PSCs evoked by minimal stimulation and the paired-pulse ratio. These results suggest that histaminergic inputs to MesV neurons through H1 receptors are involved in the suppression of the jaw-closing reflex although histamine depolarizes MesV neurons and/or MMNs. PMID:25904711

Surface electromyographic evaluation of jaw muscles in children with unilateral crossbite and lateral shift in the early mixed dentition. Sexual dimorphism

PubMed Central

Lenguas, Leticia; Alarcón, José-Antonio; Venancio, Filipa; Kassem, Marta

2012-01-01

Objectives: To examine the activity of jaw muscles at rest and during maximal voluntary clenching (MVC) in children with unilateral posterior crossbite (UPXB) and functional lateral shift in the early mixed dentition and to evaluate sex differences. Material and Methods: The sample included 30 children (15 males, 15 females) aged 6 to 10 years old, with UPXB and functional mandibular lateral shift (≥1.5 mm) in the early mixed dentition. sEMG activity coming from the muscle areas (anterior temporalis [AT], posterior temporalis [PT], masseter [MA] and suprahyoid [SH]) were obtained from both the crossbite (XB) and noncrossbite (NONXB) sides at mandibular rest position. sEMG acti-vity of the bilateral AT and MA muscles sides was obtained during MVC. Asymmetry and activity indexes were calculated for each muscle area at rest and during MVC; the MA/TA ratio during MVC was also determined. Results: At rest, no differences were found between sexes for any muscle areas or asymmetry and activity indexes. No differences were found between XB and NONXB sides. During MVC, however, significant sex differences were found in AT and MA activity, with higher sEMG values in males than in females, on both XB and NONXB sides. Asymmetry indexes, activity indexes and MA/AT ratios did not show significant differences between the sexes. Activity was symmetric both in males and in females. Conclusions: At rest, no sex differences were found, but during MVC males showed higher activity than did females in both XB and NONXB AT and MA muscle areas. Muscular activity was symmetrical at rest and during MVC in both sexes. Sexual dimorphism should be considered in the diagnosis and treatment of UPXB and lateral shift in the early mixed dentition. Key words:Unilateral crossbite, mandibular shift, jaw muscles, sEMG, early mixed dentition. PMID:22926468

Effects of microgravity on muscle and cerebral cortex: a suggested interaction

NASA Astrophysics Data System (ADS)

D'Amelio, F.; Fox, R. A.; Wu, L. C.; Daunton, N. G.; Corcoran, M. L.

The ``slow'' antigravity muscle adductor longus was studied in rats after 14 days of spaceflight (SF). The techniques employed included standard methods for light microscopy, neural cell adhesion molecule (N-CAM) immunocytochemistry and electron microscopy. Light and electron microscopy revealed myofiber atrophy, segmental necrosis and regenerative myofibers. Regenerative myofibers were N-CAM immunoreactive (N-CAM-IR). The neuromuscular junctions showed axon terminals with a decrease or absence of synaptic vesicles, degenerative changes, vacant axonal spaces and changes suggestive of axonal sprouting. No alterations of muscle spindles was seen either by light or electron microscopy. These observations suggest that muscle regeneration and denervation and synaptic remodeling at the level of the neuromuscular junction may take place during spaceflight. In a separate study, GABA immunoreactivity (GABA-IR) was evaluated at the level of the hindlimb representation of the rat somatosensory cortex after 14 days of hindlimb unloading by tail suspension (``simulated'' microgravity). A reduction in number of GABA-immunoreactive cells with respect to the control animals was observed in layer Va and Vb. GABA-IR terminals were also reduced in the same layers, particularly those terminals surrounding the soma and apical dendrites of pyramidal cells in layer Vb. On the basis of previous morphological and behavioral studies of the neuromuscular system after spaceflight and hindlimb suspension it is suggested that after limb unloading there are alterations of afferent signaling and feedback information from intramuscular receptors to the cerebral cortex due to modifications in the reflex organization of hindlimb muscle groups. We propose that the changes observed in GABA immunoreactivity of cells and terminals is an expression of changes in their modulatory activity to compensate for the alterations in the afferent information.

Immunomodulation of afferent neurons in guinea-pig isolated airway.

PubMed

Riccio, M M; Myers, A C; Undem, B J

1996-03-01

1. The trachea, larynx and main bronchi with the right vagus nerve and nodose ganglion were isolated from guinea-pigs passively immunized 24 h previously with serum containing anti-ovalbumin antibody. 2. The airways were placed in one compartment of a Perspex chamber for recording of isometric tension while the nodose ganglion and attached vagus nerve were pulled into another compartment. Action potentials arriving from single airway afferent nerve endings were monitored extracellularly using a glass microelectrode positioned near neuronal cell bodies in the ganglion. Mechanosensitivity of the nerve endings was quantified using calibrated von Frey filaments immediately before and after exposure to antigen (10 micrograms ml-1 ovalbumin). 3. Ten endings responded to the force exerted by the lowest filament (0.078 mN) and were not further investigated. In airways from thirteen immunized guinea-pigs, the mechanical sensitivity of A delta afferent fibres (conduction velocity = 4.3 +/- 0.6 m s-1) was enhanced 4.1 +/- 0.9-fold following airway exposure to antigen (P < 0.005). Mechanical sensitivities of afferent fibres (conduction velocity = 4.3 +/- 0.6 m s-1) from non-immunized control guinea-pig airways were unaffected by antigen (n = 13). 4. Antigen did not overtly cause action potential generation except in one instance when the receptive field was located over the smooth muscle. This ending also responded to methacholine suggesting that spatial changes in the receptive field, induced by muscle contraction, were responsible for the activation. 5. The mediators responsible for these effects are unknown, although histamine, prostaglandins, leukotrienes and tachykinins do not appear to be essential. The increase in mechanical responsiveness was not associated with the smooth muscle contraction since leukotriene C4, histamine and tachykinins, which all caused a similar contraction to antigen, did not affect mechanical thresholds. Moreover, the antigen-induced increases in

"Fast" and "slow" skeleto-fusimotor innervation in cat tenuissimus spindles; a study with the glycogen-depletion method.

PubMed

Jami, L; Lan-Couton, D; Malmgren, K; Petit, J

1978-07-01

The glycogen-depletion method was used to investigate the motor supply to tenuissimus with respect to the presence of fast beta axons and to assess the total proportion of both fast and slow beta-innervated spindles in this muscle. In a first series of 5 expts., groups of motor axons with conduction velocities higher than 85 m/s were repetitively stimulated so as to produce glycogen depletion in the muscle fibres they innervated. The whole muscle was then quick-frozen, serially cut, stained to demonstrate glycogen and examined for intrafusal glycogen depletion. Zones of glycogen depletion were found in 16 of the 46 examined spindles; they were most frequently located in the longest of the chain intrafusal muscle fibres. Since it is known that there are no purely fusimotor axons to tenuissimus with conduction velocities above 50 m/s, it was concluded that beta axons are present among the fastest axons to this muscle. In a second series of 5 expts. as many motor axons as possible with conduction velocities above 60 m/s were stimulated. Zones of glycogen depletion were found in 19 of the 47 examined spindles. They affected chain fibres in about half of the instances and bag1 fibers in the others. As this latter location is characteristic of slow dynamic beta axons, it was concluded that both slow and fast beta axons occur regularly in the motor supply to tenuissimus. beta-innervation is present in at least 40% of tenuissimus spindles with almost no convergence of fast and slow beta axons onto the same spindle.

A bioinspired flexible organic artificial afferent nerve

NASA Astrophysics Data System (ADS)

Kim, Yeongin; Chortos, Alex; Xu, Wentao; Liu, Yuxin; Oh, Jin Young; Son, Donghee; Kang, Jiheong; Foudeh, Amir M.; Zhu, Chenxin; Lee, Yeongjun; Niu, Simiao; Liu, Jia; Pfattner, Raphael; Bao, Zhenan; Lee, Tae-Woo

2018-06-01

The distributed network of receptors, neurons, and synapses in the somatosensory system efficiently processes complex tactile information. We used flexible organic electronics to mimic the functions of a sensory nerve. Our artificial afferent nerve collects pressure information (1 to 80 kilopascals) from clusters of pressure sensors, converts the pressure information into action potentials (0 to 100 hertz) by using ring oscillators, and integrates the action potentials from multiple ring oscillators with a synaptic transistor. Biomimetic hierarchical structures can detect movement of an object, combine simultaneous pressure inputs, and distinguish braille characters. Furthermore, we connected our artificial afferent nerve to motor nerves to construct a hybrid bioelectronic reflex arc to actuate muscles. Our system has potential applications in neurorobotics and neuroprosthetics.

Automated mitotic spindle tracking suggests a link between spindle dynamics, spindle orientation, and anaphase onset in epithelial cells

PubMed Central

Larson, Matthew E.; Bement, William M.

2017-01-01

Proper spindle positioning at anaphase onset is essential for normal tissue organization and function. Here we develop automated spindle-tracking software and apply it to characterize mitotic spindle dynamics in the Xenopus laevis embryonic epithelium. We find that metaphase spindles first undergo a sustained rotation that brings them on-axis with their final orientation. This sustained rotation is followed by a set of striking stereotyped rotational oscillations that bring the spindle into near contact with the cortex and then move it rapidly away from the cortex. These oscillations begin to subside soon before anaphase onset. Metrics extracted from the automatically tracked spindles indicate that final spindle position is determined largely by cell morphology and that spindles consistently center themselves in the XY-plane before anaphase onset. Finally, analysis of the relationship between spindle oscillations and spindle position relative to the cortex reveals an association between cortical contact and anaphase onset. We conclude that metaphase spindles in epithelia engage in a stereotyped “dance,” that this dance culminates in proper spindle positioning and orientation, and that completion of the dance is linked to anaphase onset. PMID:28100633

Jaw-opening reflex and corticobulbar motor excitability changes during quiet sleep in non-human primates.

PubMed

Yao, Dongyuan; Lavigne, Gilles J; Lee, Jye-Chang; Adachi, Kazunori; Sessle, Barry J

2013-02-01

To test the hypothesis that the reflex and corticobulbar motor excitability of jaw muscles is reduced during sleep. Polysomnographic recordings in the electrophysiological study. University sleep research laboratories. The reflex and corticobulbar motor excitability of jaw muscles was determined during the quiet awake state (QW) and quiet sleep (QS) in monkeys (n = 4). During QS sleep, compared to QW periods, both tongue stimulation-evoked jaw-opening reflex peak and root mean square amplitudes were significantly decreased with stimulations at 2-3.5 × thresholds (P < 0.001). The jaw-opening reflex latency during sleep was also significantly longer than during QW. Intracortical microstimulation (ICMS) within the cortical masticatory area induced rhythmic jaw movements at a stable threshold (≤ 60 μA) during QW; but during QS, ICMS failed to induce any rhythmic jaw movements at the maximum ICMS intensity used, although sustained jaw-opening movements were evoked at significantly increased threshold (P < 0.001) in one of the monkeys. Similarly, during QW, ICMS within face primary motor cortex induced orofacial twitches at a stable threshold (≤ 35 μA), but the ICMS thresholds were elevated during QS. Soon after the animal awoke, rhythmic jaw movements and orofacial twitches could be evoked at thresholds similar to those before QS. The results suggest that the excitability of reflex and corticobulbar-evoked activity in the jaw motor system is depressed during QS.

Deranged jaw-neck motor control in whiplash-associated disorders.

PubMed

Eriksson, Per-Olof; Zafar, Hamayun; Häggman-Henrikson, Birgitta

2004-02-01

Recent findings of simultaneous and well coordinated head-neck movements during single as well as rhythmic jaw opening-closing tasks has led to the conclusion that 'functional jaw movements' are the result of activation of jaw as well as neck muscles, leading to simultaneous movements in the temporomandibular, atlanto-occipital and cervical spine joints. It can therefore be assumed that disease or injury to any of these joint systems would disturb natural jaw function. To test this hypothesis, amplitudes, temporal coordination, and spatiotemporal consistency of concomitant mandibular and head-neck movements during single maximal jaw opening-closing tasks were analysed in 25 individuals suffering from whiplash-associated disorders (WAD) using optoelectronic movement recording technique. In addition, the relative durations for which the head position was equal to, leading ahead of, or lagging behind the mandibular position during the entire jaw opening-closing cycle were determined. Compared with healthy individuals, the WAD group showed smaller amplitudes, and changed temporal coordination between mandibular and head-neck movements. No divergence from healthy individuals was found for the spatiotemporal consistency or for the analysis during the entire jaw opening-closing cycle. These findings in the WAD group of a 'faulty', but yet consistent, jaw-neck behavior may reflect a basic importance of linked control of the jaw and neck sensory-motor systems. In conclusion, the present results suggest that neck injury is associated with deranged control of mandibular and head-neck movements during jaw opening-closing tasks, and therefore might compromise natural jaw function.

Fatigue-related firing of distal muscle nociceptors reduces voluntary activation of proximal muscles of the same limb.

PubMed

Kennedy, David S; McNeil, Chris J; Gandevia, Simon C; Taylor, Janet L

2014-02-15

With fatiguing exercise, firing of group III/IV muscle afferents reduces voluntary activation and force of the exercised muscles. These afferents can also act across agonist/antagonist pairs, reducing voluntary activation and force in nonfatigued muscles. We hypothesized that maintained firing of group III/IV muscle afferents after a fatiguing adductor pollicis (AP) contraction would decrease voluntary activation and force of AP and ipsilateral elbow flexors. In two experiments (n = 10) we examined voluntary activation of AP and elbow flexors by measuring changes in superimposed twitches evoked by ulnar nerve stimulation and transcranial magnetic stimulation of the motor cortex, respectively. Inflation of a sphygmomanometer cuff after a 2-min AP maximal voluntary contraction (MVC) blocked circulation of the hand for 2 min and maintained firing of group III/IV muscle afferents. After a 2-min AP MVC, maximal AP voluntary activation was lower with than without ischemia (56.2 ± 17.7% vs. 76.3 ± 14.6%; mean ± SD; P < 0.05) as was force (40.3 ± 12.8% vs. 57.1 ± 13.8% peak MVC; P < 0.05). Likewise, after a 2-min AP MVC, elbow flexion voluntary activation was lower with than without ischemia (88.3 ± 7.5% vs. 93.6 ± 3.9%; P < 0.05) as was torque (80.2 ± 4.6% vs. 86.6 ± 1.0% peak MVC; P < 0.05). Pain during ischemia was reported as Moderate to Very Strong. Postfatigue firing of group III/IV muscle afferents from the hand decreased voluntary drive and force of AP. Moreover, this effect decreased voluntary drive and torque of proximal unfatigued muscles, the elbow flexors. Fatigue-sensitive group III/IV muscle nociceptors act to limit voluntary drive not only to fatigued muscles but also to unfatigued muscles within the same limb.

Jaw lever analysis of Hawaiian gobioid stream fishes: a simulation study of morphological diversity and functional performance.

PubMed

Maie, Takashi; Schoenfuss, Heiko L; Blob, Richard W

2009-08-01

Differences in feeding behavior and performance among the five native Hawaiian gobioid stream fishes (Sicyopterus stimpsoni, Lentipes concolor, Awaous guamensis, Stenogobius hawaiiensis, and Eleotris sandwicensis) have been proposed based on the skeletal anatomy of their jaws and dietary specialization. However, performance of the feeding apparatus likely depends on the proportions and configurations of the jaw muscles and the arrangement of the jaw skeleton. We used a published mathematical model of muscle function to evaluate potential differences in jaw closing performance and their correlations with morphology among these species. For example, high output force calculated for the adductor mandibulae muscles (A2 and A3) of both A. guamensis and E. sandwicensis matched expectations based on the morphology of these species because these muscles are larger than in the other species. In contrast, Stenogobius hawaiiensis exhibited an alternative morphological strategy for achieving high relative output forces of both A2 and A3, in which the placement and configuration of the muscles conveyed high mechanical advantage despite only moderate cross-sectional areas. These differing anatomical pathways to similar functional performance suggest a pattern of many-to-one mapping of morphology to performance. In addition, a functional differentiation between A2 and A3 was evident for all species, in which A2 was better suited for producing forceful jaw closing and A3 for rapid jaw closing. Thus, the diversity of feeding performance of Hawaiian stream gobies seems to reflect a maintenance of functional breadth through the retention of some primitive traits in combination with novel functional capacities in several species. (c) 2009 Wiley-Liss, Inc.

Active touch and self-motion encoding by Merkel cell-associated afferents

PubMed Central

Severson, Kyle S.; Xu, Duo; Van de Loo, Margaret; Bai, Ling; Ginty, David D.; O’Connor, Daniel H.

2017-01-01

Summary Touch perception depends on integrating signals from multiple types of peripheral mechanoreceptors. Merkel-cell associated afferents are thought to play a major role in form perception by encoding surface features of touched objects. However, activity of Merkel afferents during active touch has not been directly measured. Here, we show that Merkel and unidentified slowly adapting afferents in the whisker system of behaving mice respond to both self-motion and active touch. Touch responses were dominated by sensitivity to bending moment (torque) at the base of the whisker and its rate of change, and largely explained by a simple mechanical model. Self-motion responses encoded whisker position within a whisk cycle (phase), not absolute whisker angle, and arose from stresses reflecting whisker inertia and activity of specific muscles. Thus, Merkel afferents send to the brain multiplexed information about whisker position and surface features, suggesting that proprioception and touch converge at the earliest neural level. PMID:28434802

Interdependency between mechanical parameters and afferent nerve discharge in remodeled diabetic Goto-Kakizaki rat intestine.

PubMed

Zhao, Jingbo; Yang, Jian; Liao, Donghua; Gregersen, Hans

2017-01-01

Gastrointestinal disorders are very common in diabetic patients, but the pathogenesis is still not well understood. Peripheral afferent nerves may be involved due to the complex regulation of gastrointestinal function by the enteric nervous system. We aimed to characterize the stimulus-response function of afferent fibers innervating the jejunum in the Goto-Kakizaki (GK) type 2 diabetic rat model. A key question is whether changes in afferent firing arise from remodeled tissue or from adaptive afferent processes. Seven 32-week-old male GK rats and seven age-matched normal Wistar rats were studied. Firing from mesenteric afferent nerves was recorded in excised jejunal segments of seven GK rats and seven normal Wistar rats during ramp test, stress relaxation test, and creep test. The circumferential stress-strain, spike rate increase ratio (SRIR), and single unit firing rates were calculated for evaluation of interdependency of the mechanical stimulations and the afferent nerve discharge. Elevated sensitivity to mechanical stimuli was found for diabetic nerve bundles and single unit activity ( P <0.05). The stress relaxed less in the diabetic intestinal segment ( P <0.05). Linear association between SRIR and the thickness of circumferential muscle layer was found at high stress levels as well as for SRIR and the glucose level. Altered viscoelastic properties and elevated mechanosensitivity were found in the GK rat intestine. The altered nerve signaling is related to muscle layer remodeling and glucose levels and may contribute to gastrointestinal symptoms experienced by diabetic patients.

Changes in pennation with joint angle and muscle torque: in vivo measurements in human brachialis muscle.

PubMed Central

Herbert, R D; Gandevia, S C

1995-01-01

1. Estimates of pennation in human muscles are usually obtained from cadavers. In this study, pennation of human brachialis was measured in vivo using sonography. Effects of static and dynamic changes in elbow angle and torque were investigated. 2. Pennation was measured in eight subjects using an 80 mm, 5 MHz, linear-array ultrasound transducer to generate sagittal images of the brachialis during maximal and submaximal isometric contractions at various elbow angles. It was shown that estimates of pennation were reproducible, representative of measurements made throughout the belly of the muscle and not distorted by compression of the muscle with the transducer or rotation of the muscle out of the plane of the transducer. 3. Mean resting pennation was 9.0 +/- 2.0 deg (S.D., range 6.5-12.9 deg). When the muscle was relaxed there was no effect of elbow angle on pennation. However, during a maximal isometric contraction (MVC), with the elbow flexed to 90 deg, pennation increased non-linearly with elbow torque to between 22 and 30 deg (mean 24.7 +/- 2.4 deg). The effect of increasing torque was small when the elbow was fully extended. The relationship between elbow angle, elbow torque and brachialis pennation suggests that the relaxed brachialis muscle is slack over much of its physiological range of lengths. 4. There was no hysteresis in the relationship between torque and pennation during slow isometric contractions (0.2 MVC s-1), and the relationship between elbow angle and pennation was similar during slow shortening and lengthening contractions. 5. Two consequences follow from these findings. Firstly, intramuscular mechanics are complex and simple planar models of muscles underestimate the increases in pennation which occur during muscle contraction. Second, spindle afferents from relaxed muscles may not encode joint angle over the full range of movement. Images Figure 2 PMID:7602542

Orthodontic treatment-induced temporal alteration of jaw-opening reflex excitability.

PubMed

Sasaki, Au; Hasegawa, Naoya; Adachi, Kazunori; Sakagami, Hiroshi; Suda, Naoto

2017-10-01

The impairment of orofacial motor function during orthodontic treatment needs to be addressed, because most orthodontic patients experience pain and motor excitability would be affected by pain. In the present study, the temporal alteration of the jaw-opening reflex excitability was investigated to determine if orthodontic treatment affects orofacial motor function. The excitability of jaw-opening reflex evoked by electrical stimulation on the gingiva and recorded bilaterally in the anterior digastric muscles was evaluated at 1 (D1), 3 (D3), and 7 days (D7) after orthodontic force application to the teeth of right side; morphological features (e.g., osteoclast genesis and tooth movement) were also evaluated. To clarify the underlying mechanism of orthodontic treatment-induced alteration of orofacial motor excitability, analgesics were administrated for 1 day. At D1 and D3, orthodontic treatment significantly decreased the threshold for inducing the jaw-opening reflex but significantly increased the threshold at D7. Other parameters of the jaw-opening reflex were also evaluated (e.g., latency, duration and area under the curve of anterior digastric muscles activity), and only the latency of the D1 group was significantly different from that of the other groups. Temporal alteration of the jaw-opening reflex excitability was significantly correlated with changes in morphological features. Aspirin (300 mg·kg -1 ·day -1 ) significantly increased the threshold for inducing the jaw-opening reflex, whereas a lower dose (75-150 mg·kg -1 ·day -1 ) of aspirin or acetaminophen (300 mg·kg -1 ·day -1 ) failed to alter the jaw-opening reflex excitability. These results suggest that an increase of the jaw-opening reflex excitability can be induced acutely by orthodontic treatment, possibly through the cyclooxygenase activation. NEW & NOTEWORTHY It is well known that motor function is affected by pain, but the effect of orthodontic treatment-related pain on the trigeminal

Increased sternocleidomastoid, but not trapezius, muscle activity in response to increased chewing load.

PubMed

Häggman-Henrikson, Birgitta; Nordh, Erik; Eriksson, Per-Olof

2013-10-01

Previous findings, during chewing, that boluses of larger size and harder texture result in larger amplitudes of both mandibular and head-neck movements suggest a relationship between increased chewing load and incremental recruitment of jaw and neck muscles. The present report evaluated jaw (masseter and digastric) and neck [sternocleidomastoid (SCM) and trapezius] muscle activity during the chewing of test foods of different sizes and textures by 10 healthy subjects. Muscle activity was recorded by surface electromyography and simultaneous mandibular and head movements were recorded using an optoelectronic technique. Each subject performed continuous jaw-opening/jaw-closing movements whilst chewing small and large boluses of chewing gum and rubber silicone (Optosil). For jaw opening/jaw closing without a bolus, SCM activity was recorded for jaw opening concomitantly with digastric activity. During chewing, SCM activity was recorded for jaw closing concomitantly with masseter activity. Trapezius activity was present in some, but not all, cycles. For the masseter and SCM muscles, higher activity was seen with larger test foods, suggesting increased demand and recruitment of these muscles in response to an increased chewing load. This result reinforces the previous notion of a close functional connection between the jaw and the neck motor systems in jaw actions and has scientific and clinical significance for studying jaw function and dysfunction. © 2013 Eur J Oral Sci.

The Effect of Varying Jaw-elevator Muscle Forces on a Finite Element Model of a Human Cranium.

PubMed

Toro-Ibacache, Viviana; O'Higgins, Paul

2016-07-01

Finite element analyses simulating masticatory system loading are increasingly undertaken in primates, hominin fossils and modern humans. Simplifications of models and loadcases are often required given the limits of data and technology. One such area of uncertainty concerns the forces applied to cranial models and their sensitivity to variations in these forces. We assessed the effect of varying force magnitudes among jaw-elevator muscles applied to a finite element model of a human cranium. The model was loaded to simulate incisor and molar bites using different combinations of muscle forces. Symmetric, asymmetric, homogeneous, and heterogeneous muscle activations were simulated by scaling maximal forces. The effects were compared with respect to strain distribution (i.e., modes of deformation) and magnitudes; bite forces and temporomandibular joint (TMJ) reaction forces. Predicted modes of deformation, strain magnitudes and bite forces were directly proportional to total applied muscle force and relatively insensitive to the degree of heterogeneity of muscle activation. However, TMJ reaction forces and mandibular fossa strains decrease and increase on the balancing and working sides according to the degree of asymmetry of loading. These results indicate that when modes, rather than magnitudes, of facial deformation are of interest, errors in applied muscle forces have limited effects. However the degree of asymmetric loading does impact on TMJ reaction forces and mandibular fossa strains. These findings are of particular interest in relation to studies of skeletal and fossil material, where muscle data are not available and estimation of muscle forces from skeletal proxies is prone to error. Anat Rec, 299:828-839, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Interdependency between mechanical parameters and afferent nerve discharge in remodeled diabetic Goto-Kakizaki rat intestine

PubMed Central

Zhao, Jingbo; Yang, Jian; Liao, Donghua; Gregersen, Hans

2017-01-01

Background Gastrointestinal disorders are very common in diabetic patients, but the pathogenesis is still not well understood. Peripheral afferent nerves may be involved due to the complex regulation of gastrointestinal function by the enteric nervous system. Objective We aimed to characterize the stimulus–response function of afferent fibers innervating the jejunum in the Goto-Kakizaki (GK) type 2 diabetic rat model. A key question is whether changes in afferent firing arise from remodeled tissue or from adaptive afferent processes. Design Seven 32-week-old male GK rats and seven age-matched normal Wistar rats were studied. Firing from mesenteric afferent nerves was recorded in excised jejunal segments of seven GK rats and seven normal Wistar rats during ramp test, stress relaxation test, and creep test. The circumferential stress–strain, spike rate increase ratio (SRIR), and single unit firing rates were calculated for evaluation of interdependency of the mechanical stimulations and the afferent nerve discharge. Results Elevated sensitivity to mechanical stimuli was found for diabetic nerve bundles and single unit activity (P<0.05). The stress relaxed less in the diabetic intestinal segment (P<0.05). Linear association between SRIR and the thickness of circumferential muscle layer was found at high stress levels as well as for SRIR and the glucose level. Conclusion Altered viscoelastic properties and elevated mechanosensitivity were found in the GK rat intestine. The altered nerve signaling is related to muscle layer remodeling and glucose levels and may contribute to gastrointestinal symptoms experienced by diabetic patients. PMID:29238211

Jaw-Opening Reflex and Corticobulbar Motor Excitability Changes During Quiet Sleep in Non-Human Primates

PubMed Central

Yao, Dongyuan; Lavigne, Gilles J.; Lee, Jye-Chang; Adachi, Kazunori; Sessle, Barry J.

2013-01-01

Study Objective: To test the hypothesis that the reflex and corticobulbar motor excitability of jaw muscles is reduced during sleep. Design: Polysomnographic recordings in the electrophysiological study. Setting: University sleep research laboratories. Participants and Interventions: The reflex and corticobulbar motor excitability of jaw muscles was determined during the quiet awake state (QW) and quiet sleep (QS) in monkeys (n = 4). Measurements and Results: During QS sleep, compared to QW periods, both tongue stimulation-evoked jaw-opening reflex peak and root mean square amplitudes were significantly decreased with stimulations at 2-3.5 × thresholds (P < 0.001). The jaw-opening reflex latency during sleep was also significantly longer than during QW. Intracortical microstimulation (ICMS) within the cortical masticatory area induced rhythmic jaw movements at a stable threshold (≤ 60 μA) during QW; but during QS, ICMS failed to induce any rhythmic jaw movements at the maximum ICMS intensity used, although sustained jaw-opening movements were evoked at significantly increased threshold (P < 0.001) in one of the monkeys. Similarly, during QW, ICMS within face primary motor cortex induced orofacial twitches at a stable threshold (≤ 35 μA), but the ICMS thresholds were elevated during QS. Soon after the animal awoke, rhythmic jaw movements and orofacial twitches could be evoked at thresholds similar to those before QS. Conclusions: The results suggest that the excitability of reflex and corticobulbar-evoked activity in the jaw motor system is depressed during QS. Citation: Yao D; Lavigne GJ; Lee JC; Adachi K; Sessle BJ. Jaw-opening reflex and corticobulbar motor excitability changes during quiet sleep in non-human primates. SLEEP 2013;36(2):269-280. PMID:23372275

Population Coding of Forelimb Joint Kinematics by Peripheral Afferents in Monkeys

PubMed Central

Umeda, Tatsuya; Seki, Kazuhiko; Sato, Masa-aki; Nishimura, Yukio; Kawato, Mitsuo; Isa, Tadashi

2012-01-01

Various peripheral receptors provide information concerning position and movement to the central nervous system to achieve complex and dexterous movements of forelimbs in primates. The response properties of single afferent receptors to movements at a single joint have been examined in detail, but the population coding of peripheral afferents remains poorly defined. In this study, we obtained multichannel recordings from dorsal root ganglion (DRG) neurons in cervical segments of monkeys. We applied the sparse linear regression (SLiR) algorithm to the recordings, which selects useful input signals to reconstruct movement kinematics. Multichannel recordings of peripheral afferents were performed by inserting multi-electrode arrays into the DRGs of lower cervical segments in two anesthetized monkeys. A total of 112 and 92 units were responsive to the passive joint movements or the skin stimulation with a painting brush in Monkey 1 and Monkey 2, respectively. Using the SLiR algorithm, we reconstructed the temporal changes of joint angle, angular velocity, and acceleration at the elbow, wrist, and finger joints from temporal firing patterns of the DRG neurons. By automatically selecting a subset of recorded units, the SLiR achieved superior generalization performance compared with a regularized linear regression algorithm. The SLiR selected not only putative muscle units that were responsive to only the passive movements, but also a number of putative cutaneous units responsive to the skin stimulation. These results suggested that an ensemble of peripheral primary afferents that contains both putative muscle and cutaneous units encode forelimb joint kinematics of non-human primates. PMID:23112841

Effect of pinching-evoked pain on jaw-stretch reflexes and exteroceptive suppression periods in healthy subjects.

PubMed

Biasiotta, A; Peddireddy, A; Wang, K; Romaniello, A; Frati, A; Svensson, P; Arendt-Nielsen, L

2007-10-01

To investigate the influence of conditioning cutaneous nociceptive inputs by a new "pinch" model on the jaw-stretch reflex and the exteroceptive suppression periods (ES1 and ES2) in jaw muscles. The jaw-stretch reflex was evoked with the use of a custom-made muscle stretcher and electrical stimuli were used to evoke an early and late exteroceptive suppression period (ES1 and ES2) in the jaw-closing muscles. Electromyographic (EMG) activity was recorded bilaterally from the masseter and temporalis muscles. These brainstem reflexes were recorded in 19 healthy men (28.8+/-1.1 years) during three different conditions: one painful clip applied to the earlobe; one painful clip applied to the nostril, and four painful clips applied simultaneously to the earlobe, nostril, eyebrow, and lower lip. Pain intensity induced by the application of the clips was scored continuously by the subjects on a 100mm visual analogue scale (VAS). The highest VAS pain scores were evoked by placement of four clips (79+/-0.5mm). There was no significant modulation of the jaw-stretch reflex (ANOVAs: P=0.929), the ES1 (P=0.298) or ES2 (P=0.082) in any of the three painful conditions. Intense and tonic cutaneous pain could be elicited by this new "pinch" pain model; however, there was no significant modulation on either excitatory or inhibitory brainstem reflex responses. The novel observation that high-intensity pinch stimuli applied to the craniofacial region fail to modulate two different brainstem reflexes is in contrast to other experimental pain studies documented facilitation of the jaw-stretch reflexes or inhibition of exteroceptive suppression periods. The clinical implication of the present findings is that only some craniofacial pain conditions could be expected to show perturbation of the brainstem reflex responses.

Glutamate-evoked jaw muscle pain as a model of persistent myofascial TMD pain?

PubMed Central

Castrillon, Eduardo E.; Cairns, Brian E.; Ernberg, Malin; Wang, Kelun; Sessle, Barry; Arendt-Nielsen, Lars; Svensson, Peter

2008-01-01

Objective Compare pain-related measures and psychosocial variables between glutamate-evoked jaw muscle pain in healthy subjects (HS) and patients with persistent myofascial temporomandibular disorder (TMD) pain. Design 47 female HS and 10 female patients with persistent myofascial TMD pain participated. The HS received an injection of glutamate into the masseter muscle to model persistent myofascial TMD pain. Participants filled out a coping strategies questionnaire (CSQ), the symptom checklist 90 (SCL-90) and McGill Pain Questionnaire (MPQ). Pain intensity was assessed on an electronic visual analog scale (VAS). Pain-drawing areas, Numerical Rating Scale (NRS) scores of unpleasantness, pressure pain thresholds (PPT) and tolerance (PPTOL) were measured. Unpaired t-tests and correlation tests were used for analyses. Results The groups were significantly different when comparing the CSQ scores of control, decrease, diverting attention, increase of behavioral activities and somatization. The peak VAS pain, NRS of unpleasantness and MPQ scores were not significantly different between groups, but PPT and PPTOL were significantly lower in the TMD patients. Significant positive correlations were found in the TMD patients between peak VAS pain and CSQ catastrophizing score and SCL-90 somatization. The scores of PPTs and PPTOLs, in patients showed positive correlations with CSQ reinterpreting pain sensations scores and PPTs correlated with CSQ praying/hoping scores. Conclusions Glutamate-evoked pain responses in HS and persistent myofascial TMD pain have similar sensory-discriminative and affective-unpleasantness components but differ in psycho-social features. This study suggests that experimental designs based on glutamate injection into muscle can provide an appropriate model for elucidating persistent myofascial pain conditions. PMID:18313028

Small vertical changes in jaw relation affect motor unit recruitment in the masseter.

PubMed

Terebesi, S; Giannakopoulos, N N; Brüstle, F; Hellmann, D; Türp, J C; Schindler, H J

2016-04-01

Strategies for recruitment of masseter muscle motor units (MUs), provoked by constant bite force, for different vertical jaw relations have not previously been investigated. The objective of this study was to analyse the effect of small changes in vertical jaw relation on MU recruitment behaviour in different regions of the masseter during feedback-controlled submaximum biting tasks. Twenty healthy subjects (mean age: 24·6 ± 2·4 years) were involved in the investigation. Intra-muscular electromyographic (EMG) activity of the right masseter was recorded in different regions of the muscle. MUs were identified by the use of decomposition software, and root-mean-square (RMS) values were calculated for each experimental condition. Six hundred and eleven decomposed MUs with significantly (P < 0·001) different jaw relation-specific recruitment behaviour were organised into localised MU task groups. MUs with different task specificity in seven examined tasks were observed. The RMS EMG values obtained from the different recording sites were also significantly (P < 0·01) different between tasks. Overall MU recruitment was significantly (P < 0·05) greater in the deep masseter than in the superficial muscle. The number of recruited MUs and the RMS EMG values decreased significantly (P < 0·01) with increasing jaw separation. This investigation revealed differential MU recruitment behaviour in discrete subvolumes of the masseter in response to small changes in vertical jaw relations. These fine-motor skills might be responsible for its excellent functional adaptability and might also explain the successful management of temporomandibular disorder patients by somatic intervention, in particular by the use of oral splints. © 2015 John Wiley & Sons Ltd.

Vagal Sensory Innervation of the Gastric Sling Muscle and Antral Wall: Implications for GERD?

PubMed Central

Powley, Terry L.; Gilbert, Jared M.; Baronowsky, Elizabeth A.; Billingsley, Cherie N.; Martin, Felecia N.; Phillips, Robert J.

2012-01-01

Background The gastric sling muscle has not been investigated for possible sensory innervation, in spite of the key roles the structure plays in lower esophageal sphincter (LES) function and gastric physiology. Thus, the present experiment used tracing techniques to label vagal afferents and survey their projections in the lesser curvature. Methods Sprague Dawley rats received injections of dextran biotin into the nodose ganglia. Fourteen days post-injection, animals were euthanized and their stomachs were processed to visualize the vagal afferent innervation. In different cases, neurons, muscle cells, or interstitial cells of Cajal were counterstained. Key Results The sling muscle is innervated throughout its length by vagal afferent intramuscular arrays (IMAs) associated with interstitial cells of Cajal. In addition, the distal antral attachment site of the sling muscle is innervated by a novel vagal afferent terminal specialization, an antral web ending. The muscle wall of the distal antrum is also innervated by conventional IMAs and intraganglionic laminar endings (IGLEs), the two types of mechanoreceptors found throughout stomach smooth muscle. Conclusions & Inferences The innervation of sling muscle by IMAs, putative stretch receptors, suggests that sling sensory feedback may generate vago-vagal or other reflexes with vagal afferent limbs. The restricted distribution of afferent web endings near the antral attachments of sling fibers suggests the possibility of specialized mechanoreceptor functions linking antral and pyloric activity to the operation of the LES. Dysfunctional sling afferents could generate LES motor disturbances, or normative compensatory sensory feedback from the muscle could compromise therapies targeting only effectors. PMID:22925069

The Jaw Adductor Muscle Complex in Teleostean Fishes: Evolution, Homologies and Revised Nomenclature (Osteichthyes: Actinopterygii)

PubMed Central

Datovo, Aléssio; Vari, Richard P.

2013-01-01

The infraclass Teleostei is a highly diversified group of bony fishes that encompasses 96% of all species of living fishes and almost half of extant vertebrates. Evolution of various morphological complexes in teleosts, particularly those involving soft anatomy, remains poorly understood. Notable among these problematic complexes is the adductor mandibulae, the muscle that provides the primary force for jaw adduction and mouth closure and whose architecture varies from a simple arrangement of two segments to an intricate complex of up to ten discrete subdivisions. The present study analyzed multiple morphological attributes of the adductor mandibulae in representatives of 53 of the 55 extant teleostean orders, as well as significant information from the literature in order to elucidate the homologies of the main subdivisions of this muscle. The traditional alphanumeric terminology applied to the four main divisions of the adductor mandibulae – A1, A2, A3, and Aω – patently fails to reflect homologous components of that muscle across the expanse of the Teleostei. Some features traditionally used as landmarks for identification of some divisions of the adductor mandibulae proved highly variable across the Teleostei; notably the insertion on the maxilla and the position of muscle components relative to the path of the ramus mandibularis trigeminus nerve. The evolutionary model of gain and loss of sections of the adductor mandibulae most commonly adopted under the alphanumeric system additionally proved ontogenetically incongruent and less parsimonious than a model of subdivision and coalescence of facial muscle sections. Results of the analysis demonstrate the impossibility of adapting the alphanumeric terminology so as to reflect homologous entities across the spectrum of teleosts. A new nomenclatural scheme is proposed in order to achieve congruence between homology and nomenclature of the adductor mandibulae components across the entire Teleostei. PMID

Proprioception in the extraocular muscles of mammals and man.

PubMed

Blumer, Roland; Konacki, Kadriye Zeynep; Streicher, Johannes; Hoetzenecker, Wolfram; Blumer, Michael Josef Franz; Lukas, Julius-Robert

2006-06-01

This article summarizes the authors' previous studies on proprioceptors in extraocular muscles (EOMs) of mammals and man. They report on muscle spindles in the EOMs of man, Golgi tendon organs in the EOMs of even-toed ungulates, and palisade endings in the EOMs of the cat. Muscle spindles: Muscle spindles are present in the EOMs of some mammals and in the EOMs of man. Compared with muscle spindles in other skeletal muscles, those in human EOMs exhibit structural differences. These structural differences may indicate a special function. Golgi tendon organs: Golgi tendon organs are absent in human EOMs. Golgi tendon organs exhibiting a specific morphology are present in the EOMs of even-toed ungulates. Their high number and rich innervation indicate functional importance. Palisade endings: Palisade endings are nervous end organs confined to the EOMs of mammals and man. It is assumed that these organs have a proprioceptive function. The authors show that palisade endings are immunoreactive for antibodies against choline acetyltransferase. Neuromuscular contacts, if present in palisade endings, are alpha -bungarotoxin positive as well. Taken together, these results show that palisade endings exhibit molecular characteristics of effector organs.

Different types of spinal afferent nerve endings in stomach and esophagus identified by anterograde tracing from dorsal root ganglia.

PubMed

Spencer, Nick J; Kyloh, Melinda; Beckett, Elizabeth A; Brookes, Simon; Hibberd, Tim

2016-10-15

In visceral organs of mammals, most noxious (painful) stimuli as well as innocuous stimuli are detected by spinal afferent neurons, whose cell bodies lie in dorsal root ganglia (DRGs). One of the major unresolved questions is the location, morphology, and neurochemistry of the nerve endings of spinal afferents that actually detect these stimuli in the viscera. In the upper gastrointestinal (GI) tract, there have been many anterograde tracing studies of vagal afferent endings, but none on spinal afferent endings. Recently, we developed a technique that now provides selective labeling of only spinal afferents. We used this approach to identify spinal afferent nerve endings in the upper GI tract of mice. Animals were anesthetized, and injections of dextran-amine were made into thoracic DRGs (T8-T12). Seven days post surgery, mice were euthanized, and the stomach and esophagus were removed, fixed, and stained for calcitonin gene-related peptide (CGRP). Spinal afferent axons were identified that ramified extensively through many rows of myenteric ganglia and formed nerve endings in discrete anatomical layers. Most commonly, intraganglionic varicose endings (IGVEs) were identified in myenteric ganglia of the stomach and varicose simple-type endings in the circular muscle and mucosa. Less commonly, nerve endings were identified in internodal strands, blood vessels, submucosal ganglia, and longitudinal muscle. In the esophagus, only IGVEs were identified in myenteric ganglia. No intraganglionic lamellar endings (IGLEs) were identified in the stomach or esophagus. We present the first identification of spinal afferent endings in the upper GI tract. Eight distinct types of spinal afferent endings were identified in the stomach, and most of them were CGRP immunoreactive. J. Comp. Neurol. 524:3064-3083, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Deep tissue afferents, but not cutaneous afferents, mediate transcutaneous electrical nerve stimulation-Induced antihyperalgesia.

PubMed

Radhakrishnan, Rajan; Sluka, Kathleen A

2005-10-01

In this study we investigated the involvement of cutaneous versus knee joint afferents in the antihyperalgesia produced by transcutaneous electrical nerve stimulation (TENS) by differentially blocking primary afferents with local anesthetics. Hyperalgesia was induced in rats by inflaming one knee joint with 3% kaolin-carrageenan and assessed by measuring paw withdrawal latency to heat before and 4 hours after injection. Skin surrounding the inflamed knee joint was anesthetized using an anesthetic cream (EMLA). Low (4 Hz) or high (100 Hz) frequency TENS was then applied to the anesthetized skin. In another group, 2% lidocaine gel was injected into the inflamed knee joint, and low or high frequency TENS was applied. Control experiments were done using vehicles. In control and EMLA groups, both low and high frequency TENS completely reversed hyperalgesia. However, injection of lidocaine into the knee joint prevented antihyperalgesia produced by both low and high frequency TENS. Recordings of cord dorsum potentials showed that both low and high frequency TENS at sensory intensity activates only large diameter afferent fibers. Increasing intensity to twice the motor threshold recruits Adelta afferent fibers. Furthermore, application of EMLA cream to the skin reduces the amplitude of the cord dorsum potential by 40% to 70% for both high and low frequency TENS, confirming a loss of large diameter primary afferent input after EMLA is applied to the skin. Thus, inactivation of joint afferents, but not cutaneous afferents, prevents the antihyperalgesia effects of TENS. We conclude that large diameter primary afferent fibers from deep tissue are required and that activation of cutaneous afferents is not sufficient for TENS-induced antihyperalgesia. Transcutaneous electrical nerve stimulation (TENS) is an accepted clinical modality used for pain relief. It is generally believed that TENS analgesia is caused mainly by cutaneous afferent activation. In this study by

Vagal sensory innervation of the gastric sling muscle and antral wall: implications for gastro-esophageal reflux disease?

PubMed

Powley, T L; Gilbert, J M; Baronowsky, E A; Billingsley, C N; Martin, F N; Phillips, R J

2012-10-01

The gastric sling muscle has not been investigated for possible sensory innervation, in spite of the key roles the structure plays in lower esophageal sphincter (LES) function and gastric physiology. Thus, the present experiment used tracing techniques to label vagal afferents and survey their projections in the lesser curvature. Sprague-Dawley rats received injections of dextran biotin into the nodose ganglia. Fourteen days postinjection, animals were euthanized and their stomachs were processed to visualize the vagal afferent innervation. In different cases, neurons, muscle cells, or interstitial cells of Cajal (ICC) were counterstained. The sling muscle is innervated throughout its length by vagal afferent intramuscular arrays (IMAs) associated with ICC. In addition, the distal antral attachment site of the sling muscle is innervated by a novel vagal afferent terminal specialization, an antral web ending. The muscle wall of the distal antrum is also innervated by conventional IMAs and intraganglionic laminar endings, the two types of mechanoreceptors found throughout stomach smooth muscle. The innervation of sling muscle by IMAs, putative stretch receptors, suggests that sling sensory feedback may generate vago-vagal or other reflexes with vagal afferent limbs. The restricted distribution of afferent web endings near the antral attachments of sling fibers suggests the possibility of specialized mechanoreceptor functions linking antral and pyloric activity to the operation of the LES. Dysfunctional sling afferents could generate LES motor disturbances, or normative compensatory sensory feedback from the muscle could compromise therapies targeting only effectors. © 2012 Blackwell Publishing Ltd.

Effects of Botulinum Toxin on Jaw Motor Events during Sleep in Sleep Bruxism Patients: A Polysomnographic Evaluation

PubMed Central

Shim, Young Joo; Lee, Moon Kyu; Kato, Takafumi; Park, Hyung Uk; Heo, Kyoung; Kim, Seong Taek

2014-01-01

Study Objectives: To investigate the effects of botulinum toxin type A (BoNT-A) injection on jaw motor episodes during sleep in patients with or without orofacial pain who did not respond to oral splint treatment. Methods: Twenty subjects with a clinical diagnosis of SB completed this study. Ten subjects received bilateral BoNT-A injections (25 U per muscle) into the masseter muscles only (group A), and the other 10 received the injections into both the masseter and temporalis muscles (group B). Video-polysomnographic (vPSG) recordings were made before and at 4 weeks after injection. Rhythmic masticatory muscle activity (RMMA) and orofacial activity (OFA) were scored and analyzed for several parameters (e.g., frequency of episodes, bursts per episode, episode duration). The peak amplitude of electromyographic (EMG) activity in the two muscles was also measured. Results: BoNT-A injection did not reduce the frequency, number of bursts, or duration for RMMA episodes in the two groups. The injection decreased the peak amplitude of EMG burst of RMMA episodes in the injected muscles (p < 0.001, repeated measure ANOVA) in both groups. At 4 weeks after injection, 9 subjects self-reported reduction of tooth grinding and 18 subjects self-reported reduction of morning jaw stiffness. Conclusions: A single BoNT-A injection is an effective strategy for controlling SB for at least a month. It reduces the intensity rather than the generation of the contraction in jaw-closing muscles. Future investigations on the efficacy and safety in larger samples over a longer follow-up period are needed before establishing management strategies for SB with BoNT-A. Citation: Shim YJ; Lee MK; Kato T; Park HU; Heo K; Kim ST. Effects of botulinum toxin on jaw motor events during sleep in sleep bruxism patients: a polysomnographic evaluation. J Clin Sleep Med 2014;10(3):291-298. PMID:24634627

Ultrastructural and molecular biologic comparison of classic proprioceptors and palisade endings in sheep extraocular muscles.

PubMed

Rungaldier, Stefanie; Heiligenbrunner, Stefan; Mayer, Regina; Hanefl-Krivanek, Christiane; Lipowec, Marietta; Streicher, Johannes; Blumer, Roland

2009-12-01

To analyze and compare the structural and molecular features of classic proprioceptors like muscle spindles and Golgi tendon organs (GTOs) and putative proprioceptors (palisade endings) in sheep extraocular muscle (EOMs). The EOMs of four sheep were analyzed. Frozen sections or wholemount preparations of the samples were immunohistochemically labeled and analyzed by confocal laser scanning microscopy. Triple labeling with different combinations of antibodies against neurofilament, synaptophysin, and choline acetyltransferase (ChAT), as well as alpha-bungarotoxin and phalloidin, was performed. Microscopic anatomy of the nerve end organs was analyzed by transmission electron microscopy. The microscopic anatomy demonstrated that muscle spindles and GTOs had a perineural capsule and palisade endings a connective tissue capsule. Sensory nerve terminals in muscle spindles and GTOs contained only a few vesicles, whereas palisade nerve terminals were full of clear vesicles. Likewise, motor terminals in the muscle spindles' polar regions were full of clear vesicles. Immunohistochemistry showed that sensory nerve fibers as well as their sensory nerve terminals in muscle spindles and GTOs were ChAT-negative. Palisade endings were supplied by ChAT-positive nerve fibers, and the palisade complexes including palisade nerve terminals were also ChAT-immunoreactive. Motor terminals in muscle spindles were ChAT and alpha-bungarotoxin positive. The present study demonstrated in sheep EOMs that palisade endings are innervated by cholinergic axons exhibiting characteristics typical of motoneurons, whereas muscle spindles (except the polar regions) and GTOs are supplied by noncholinergic axons. These results raise the question of whether palisade endings are candidates for proprioceptors in EOMs.

Models of utricular bouton afferents: role of afferent-hair cell connectivity in determining spike train regularity.

PubMed

Holmes, William R; Huwe, Janice A; Williams, Barbara; Rowe, Michael H; Peterson, Ellengene H

2017-05-01

Vestibular bouton afferent terminals in turtle utricle can be categorized into four types depending on their location and terminal arbor structure: lateral extrastriolar (LES), striolar, juxtastriolar, and medial extrastriolar (MES). The terminal arbors of these afferents differ in surface area, total length, collecting area, number of boutons, number of bouton contacts per hair cell, and axon diameter (Huwe JA, Logan CJ, Williams B, Rowe MH, Peterson EH. J Neurophysiol 113: 2420-2433, 2015). To understand how differences in terminal morphology and the resulting hair cell inputs might affect afferent response properties, we modeled representative afferents from each region, using reconstructed bouton afferents. Collecting area and hair cell density were used to estimate hair cell-to-afferent convergence. Nonmorphological features were held constant to isolate effects of afferent structure and connectivity. The models suggest that all four bouton afferent types are electrotonically compact and that excitatory postsynaptic potentials are two to four times larger in MES afferents than in other afferents, making MES afferents more responsive to low input levels. The models also predict that MES and LES terminal structures permit higher spontaneous firing rates than those in striola and juxtastriola. We found that differences in spike train regularity are not a consequence of differences in peripheral terminal structure, per se, but that a higher proportion of multiple contacts between afferents and individual hair cells increases afferent firing irregularity. The prediction that afferents having primarily one bouton contact per hair cell will fire more regularly than afferents making multiple bouton contacts per hair cell has implications for spike train regularity in dimorphic and calyx afferents. NEW & NOTEWORTHY Bouton afferents in different regions of turtle utricle have very different morphologies and afferent-hair cell connectivities. Highly detailed

Modulation of the masseteric reflex by gastric vagal afferents.

PubMed

Pettorossi, V E

1983-04-01

Several investigations have shown that the vagal nerve can affect the reflex responses of the masticatory muscles acting at level either of trigeminal motoneurons or of the mesencephalic trigeminal nucleus (MTN). The present experiments have been devoted to establish the origin of the vagal afferent fibres involved in modulating the masseteric reflex. In particular, the gastric vagal afferents were taken into consideration and selective stimulations of such fibres were performed in rabbit. Conditioning electrical stimulation of truncus vagalis ventralis (TVV) reduced the excitability of the MTN cells as shown by a decrease of the antidromic response recorded from the semilunar ganglion and elicited by MTN single-shock electrical stimulation. Sympathetic and cardiovascular influences were not involved in these responses. Mechanical stimulation of gastric receptors, by means of gastric distension, clearly diminished the amplitude of twitch tension of masseteric reflex and inhibited the discharge frequency of proprioceptive MTN units. The effect was phasic and depended upon the velocity of distension. Thus the sensory volleys originating from rapid adapting receptors reach the brain stem through vagal afferents and by means of a polysynaptic connection inhibits the masseteric reflex at level of MTN cells.

FGF and TGFβ signaling link form and function during jaw development and evolution.

PubMed

Woronowicz, Katherine C; Gline, Stephanie E; Herfat, Safa T; Fields, Aaron J; Schneider, Richard A

2018-05-16

How does form arise during development and change during evolution? How does form relate to function, and what enables embryonic structures to presage their later use in adults? To address these questions, we leverage the distinct functional morphology of the jaw in duck, chick, and quail. In connection with their specialized mode of feeding, duck develop a secondary cartilage at the tendon insertion of their jaw adductor muscle on the mandible. An equivalent cartilage is absent in chick and quail. We hypothesize that species-specific jaw architecture and mechanical forces promote secondary cartilage in duck through the differential regulation of FGF and TGFβ signaling. First, we perform transplants between chick and duck embryos and demonstrate that the ability of neural crest mesenchyme (NCM) to direct the species-specific insertion of muscle and the formation of secondary cartilage depends upon the amount and spatial distribution of NCM-derived connective tissues. Second, we quantify motility and build finite element models of the jaw complex in duck and quail, which reveals a link between species-specific jaw architecture and the predicted mechanical force environment. Third, we investigate the extent to which mechanical load mediates FGF and TGFβ signaling in the duck jaw adductor insertion, and discover that both pathways are mechano-responsive and required for secondary cartilage formation. Additionally, we find that FGF and TGFβ signaling can also induce secondary cartilage in the absence of mechanical force or in the adductor insertion of quail embryos. Thus, our results provide novel insights on molecular, cellular, and biomechanical mechanisms that couple musculoskeletal form and function during development and evolution. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

The Clathrin-dependent Spindle Proteome*

PubMed Central

Rao, Sushma R.; Flores-Rodriguez, Neftali; Page, Scott L.; Wong, Chin; Robinson, Phillip J.; Chircop, Megan

2016-01-01

The mitotic spindle is required for chromosome congression and subsequent equal segregation of sister chromatids. These processes involve a complex network of signaling molecules located at the spindle. The endocytic protein, clathrin, has a “moonlighting” role during mitosis, whereby it stabilizes the mitotic spindle. The signaling pathways that clathrin participates in to achieve mitotic spindle stability are unknown. Here, we assessed the mitotic spindle proteome and phosphoproteome in clathrin-depleted cells using quantitative MS/MS (data are available via ProteomeXchange with identifier PXD001603). We report a spindle proteome that consists of 3046 proteins and a spindle phosphoproteome consisting of 5157 phosphosites in 1641 phosphoproteins. Of these, 2908 (95.4%) proteins and 1636 (99.7%) phosphoproteins are known or predicted spindle-associated proteins. Clathrin-depletion from spindles resulted in dysregulation of 121 proteins and perturbed signaling to 47 phosphosites. The majority of these proteins increased in mitotic spindle abundance and six of these were validated by immunofluorescence microscopy. Functional pathway analysis confirmed the reported role of clathrin in mitotic spindle stabilization for chromosome alignment and highlighted possible new mechanisms of clathrin action. The data also revealed a novel second mitotic role for clathrin in bipolar spindle formation. PMID:27174698

The Clathrin-dependent Spindle Proteome.

PubMed

Rao, Sushma R; Flores-Rodriguez, Neftali; Page, Scott L; Wong, Chin; Robinson, Phillip J; Chircop, Megan

2016-08-01

The mitotic spindle is required for chromosome congression and subsequent equal segregation of sister chromatids. These processes involve a complex network of signaling molecules located at the spindle. The endocytic protein, clathrin, has a "moonlighting" role during mitosis, whereby it stabilizes the mitotic spindle. The signaling pathways that clathrin participates in to achieve mitotic spindle stability are unknown. Here, we assessed the mitotic spindle proteome and phosphoproteome in clathrin-depleted cells using quantitative MS/MS (data are available via ProteomeXchange with identifier PXD001603). We report a spindle proteome that consists of 3046 proteins and a spindle phosphoproteome consisting of 5157 phosphosites in 1641 phosphoproteins. Of these, 2908 (95.4%) proteins and 1636 (99.7%) phosphoproteins are known or predicted spindle-associated proteins. Clathrin-depletion from spindles resulted in dysregulation of 121 proteins and perturbed signaling to 47 phosphosites. The majority of these proteins increased in mitotic spindle abundance and six of these were validated by immunofluorescence microscopy. Functional pathway analysis confirmed the reported role of clathrin in mitotic spindle stabilization for chromosome alignment and highlighted possible new mechanisms of clathrin action. The data also revealed a novel second mitotic role for clathrin in bipolar spindle formation. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

[Readjustment of the efferent activity of the scratching generator in response to stimulation of muscle afferents of the hindlimb of the decerebrate immobilized cat].

PubMed

Shimanskiĭ, Iu P; Baev, K V

1987-01-01

Rebuildings of the scratching generator activity caused by phasic electrical stimulation of ipsilateral hindlimb muscle nerves during different hindlimb positions were studied in decerebrated immobilized cats. Strong dependence of these rebuildings on the stimulation phase was observed. The character of the "scratch" cycle duration rebuilding was formed by the scratching generator tendency to bring efferent activity into such correlation with the stimulus that the stimulation moment coincided with the moment of efferent activity phase triggering. Phasic altering of the efferent activity intensity rebuilding was observed against a background of "aiming" and "scratching" activity correlation shift in the direction of strengthening activation of muscles innervated by the stimulated nerve. This rebuilding was intensified when the hindlimb deflects from the aimed position in the direction of corresponding muscles stretching. Physiological sense of "rebuilding absence phases" is discussed. It is postulated that absence of the duration and intensity changes can be achieved simultaneously only with definite correlation between phase and intensity of the afferent impulsation burst.

Evidence from the use of vibration during procaine nerve block that the spindle group II fibres contribute excitation to the tonic stretch reflex of the decerebrate cat

PubMed Central

McGrath, G. J.; Matthews, P. B. C.

1973-01-01

1. Experiments have been performed to test the hypothesis that the group II fibres from the secondary endings of the muscle spindle provide an excitatory contribution to the tonic stretch reflex of the decerebrate cat. They have consisted of studying the effect of fusimotor paralysis by procaine, applied to the muscle nerve, on the reflex response to the combined stimuli of stretch (5-9 mm at 5 mm/sec) and of high-frequency vibration (100-150 Hz, 150 μm). 2. The reflex response to the combined stimuli was found to be paralysed in two distinct stages which paralleled those of the ordinary stretch reflex described earlier. The two phases of paralysis may be attributed to an early paralysis of the γ efferents followed by a later paralysis of the Ia afferents and α motor fibres. However, the Ia discharges elicited by the combined stimuli, unlike those elicited by simple stretch, should have remained unchanged on γ efferent paralysis since the Ia firing frequency may be presumed to have been clamped at the vibration frequency by the occurrence of one-to-one `driving'. The early reduction of the response to the combined stimuli may thus be attributed to the removal of a stretchevoked autogenetic excitatory input other than that long known to be provided by the Ia pathway. This supports the view that the spindle group II fibres have such an action, since their firing will be appropriately reduced on γ efferent paralysis by removal of their pre-existing fusimotor bias; there is no evidence for the existence of any other group of fibres with the right properties. 3. Recording of compound action potentials and of single units confirmed the great sensitivity of the γ efferents to procaine but showed that the group II fibres were nearly as resistant as the Ia fibres and α motor fibres. 4. The reliability of one-to-one driving of the Ia discharges by the vibration was tested in control experiments in which the reflex was elicited by an asymmetrical vibratory waveform

Three dimensional digital reconstruction of the jaw adductor musculature of the extinct marsupial giant Diprotodon optatum

PubMed Central

2014-01-01

The morphology and arrangement of the jaw adductor muscles in vertebrates reflects masticatory style and feeding processes, diet and ecology. However, gross muscle anatomy is rarely preserved in fossils and is, therefore, heavily dependent on reconstructions. An undeformed skull of the extinct marsupial, Diprotodon optatum, recovered from Pleistocene sediments at Bacchus Marsh in Victoria, represents the most complete and best preserved specimen of the species offering a unique opportunity to investigate functional anatomy. Computed tomography (CT) scans and digital reconstructions make it possible to visualise internal cranial anatomy and predict location and morphology of soft tissues, including muscles. This study resulted in a 3D digital reconstruction of the jaw adductor musculature of Diprotodon, revealing that the arrangement of muscles is similar to that of kangaroos and that the muscle actions were predominantly vertical. 3D digital muscle reconstructions provide considerable advantages over 2D reconstructions for the visualisation of the spatial arrangement of the individual muscles and the measurement of muscle properties (length, force vectors and volume). Such digital models can further be used to estimate muscle loads and attachment sites for biomechanical analyses. PMID:25165628

Relationship between function of masticatory muscle in mouse and properties of muscle fibers.

PubMed

Abe, Shinichi; Hiroki, Emi; Iwanuma, Osamu; Sakiyama, Koji; Shirakura, Yoshitaka; Hirose, Daiki; Shimoo, Yoshiaki; Suzuki, Masashi; Ikari, Yasutoyo; Kikuchi, Ryusuke; Ide, Yoshinobu; Yoshinari, Masao

2008-05-01

Mammals exhibit marked morphological differences in the muscles surrounding the jaw bone due to differences in eating habits. Furthermore, the myofiber properties of the muscles differ with function. Since the muscles in the oral region have various functions such as eating, swallowing, and speech, it is believed that the functional role of each muscle differs. Therefore, to clarify the functional role of each masticatory muscle, the myofiber properties of the adult mouse masticatory muscles were investigated at the transcriptional level. Expression of MyHC-2b with a fast contraction rate and strong force was frequently noted in the temporal and masseter muscles. This suggests that the temporal and masseter muscles are closely involved in rapid antero-posterior masticatory movement, which is characteristic in mice. Furthermore, expression of MyHC-1 with a low contraction rate and weak continuous force was frequently detected in the lateral pterygoid muscle. This suggests that, in contrast to other masticatory muscles, mouse lateral pterygoid muscle is not involved in fast masticatory movement, but is involved in functions requiring continuous force such as retention of jaw position. This study revealed that muscles with different roles function comprehensively during complicated masticatory movement.

Spindle

DOE Office of Scientific and Technical Information (OSTI.GOV)

2013-04-04

Spindle is software infrastructure that solves file system scalabiltiy problems associated with starting dynamically linked applications in HPC environments. When an HPC applications starts up thousands of pricesses at once, and those processes simultaneously access a shared file system to look for shared libraries, it can cause significant performance problems for both the application and other users. Spindle scalably coordinates the distribution of shared libraries to an application to avoid hammering the shared file system.

Ultrastructural and molecular biologic comparison of classical proprioceptors and palisade endings in sheep extraocular muscles

PubMed Central

RUNGALDIER, Stefanie; HEILIGENBRUNNER, Stefan; MAYER, Regina; HANEFL-KRIVANEK, Christiane; LIPOWEC, Marietta; STREICHER, Johannes; BLUMER, Roland

2016-01-01

Purpose To analyze and compare the structural and molecular features of classical proprioceptors like muscle spindles and Golgi tendon organs (GTOs) and putative proprioceptors (palisade endings) in sheep extraocular muscle (EOMs). Methods The EOMs of four sheep were analyzed. Frozen sections or whole mount preparations of the samples were immunohistochemically labeled and analyzed by confocal laser scanning microscopy. Triple labeling with different combinations of antibodies against neurofilament, synaptophysin and choline acetyltransferase (ChAT) as well as α-bungarotoxin and phalloidin was performed. Microscopic anatomy of the nerve end organs was analyzed by transmission electron microscopy. Results The microscopic anatomy demonstrated that muscle spindles and GTOs had a perineural capsule and palisade endings a connective tissue capsule. Sensory nerve terminals in muscle spindles and GTOs contained only few vesicles whereas palisade nerve terminals were full of clear vesicles. Likewise, motor terminals in the muscle spindles’ polar regions were full of clear vesicles. Immunohistochemistry showed that sensory nerve fibers as well as their sensory nerve terminals in muscle spindles and GTOs were ChAT-negative. Palisade endings were supplied by ChAT-positive nerve fibers and the palisade complexes including palisade nerve terminals were also ChAT-immunoreactive. Motor terminals in muscle spindles were ChAT and α-bungarotoxin -positive. Conclusions The present study demonstrated in sheep EOMs that palisade endings are innervated by cholinergic axons exhibiting characteristics typical for motoneurons whereas muscle spindles (except the polar regions) and GTOs are supplied by non-cholinergic axons. These results question whether palisade endings are candidates for proprioceptors in EOMs. PMID:19553627

Physiological recruitment of motor units by high-frequency electrical stimulation of afferent pathways.

PubMed

Dideriksen, Jakob L; Muceli, Silvia; Dosen, Strahinja; Laine, Christopher M; Farina, Dario

2015-02-01

Neuromuscular electrical stimulation (NMES) is commonly used in rehabilitation, but electrically evoked muscle activation is in several ways different from voluntary muscle contractions. These differences lead to challenges in the use of NMES for restoring muscle function. We investigated the use of low-current, high-frequency nerve stimulation to activate the muscle via the spinal motoneuron (MN) pool to achieve more natural activation patterns. Using a novel stimulation protocol, the H-reflex responses to individual stimuli in a train of stimulation pulses at 100 Hz were reliably estimated with surface EMG during low-level contractions. Furthermore, single motor unit recruitment by afferent stimulation was analyzed with intramuscular EMG. The results showed that substantially elevated H-reflex responses were obtained during 100-Hz stimulation with respect to a lower stimulation frequency. Furthermore, motor unit recruitment using 100-Hz stimulation was not fully synchronized, as it occurs in classic NMES, and the discharge rates differed among motor units because each unit was activated only after a specific number of stimuli. The most likely mechanism behind these observations is the temporal summation of subthreshold excitatory postsynaptic potentials from Ia fibers to the MNs. These findings and their interpretation were also verified by a realistic simulation model of afferent stimulation of a MN population. These results suggest that the proposed stimulation strategy may allow generation of considerable levels of muscle activation by motor unit recruitment that resembles the physiological conditions. Copyright © 2015 the American Physiological Society.

Role of stag beetle jaw bending and torsion in grip on rivals.

PubMed

Goyens, Jana; Dirckx, Joris; Piessen, Maxim; Aerts, Peter

2016-01-01

In aggressive battles, the extremely large male stag beetle jaws have to withstand strongly elevated bite forces. We found several adaptations of the male Cyclommatus metallifer jaw morphology for enhanced robustness that conspecific females lack. As a result, males improve their grip on opponents and they maintain their safety factor (5.2-7.2) at the same level as that of females (6.8), despite their strongly elevated bite muscle force (3.9 times stronger). Males have a higher second moment of area and torsion constant than females, owing to an enhanced cross-sectional area and shape. These parameters also increase faster with increasing bending moment towards the jaw base in males than in females. Male jaws are more bending resistant against the bite reaction force than against perpendicular forces (which remain lower in battles). Because of the triangular cross section of the male jaw base, it twists more easily than it bends. This torsional flexibility creates a safety system against overload that, at the same time, secures a firm grip on rivals. We found no structural mechanical function of the large teeth halfway along the male jaws. Therefore, it appears that the main purpose of these teeth is a further improvement of grip on rivals. © 2016 The Author(s).

Role of stag beetle jaw bending and torsion in grip on rivals

PubMed Central

Goyens, Jana; Dirckx, Joris; Piessen, Maxim; Aerts, Peter

2016-01-01

In aggressive battles, the extremely large male stag beetle jaws have to withstand strongly elevated bite forces. We found several adaptations of the male Cyclommatus metallifer jaw morphology for enhanced robustness that conspecific females lack. As a result, males improve their grip on opponents and they maintain their safety factor (5.2–7.2) at the same level as that of females (6.8), despite their strongly elevated bite muscle force (3.9 times stronger). Males have a higher second moment of area and torsion constant than females, owing to an enhanced cross-sectional area and shape. These parameters also increase faster with increasing bending moment towards the jaw base in males than in females. Male jaws are more bending resistant against the bite reaction force than against perpendicular forces (which remain lower in battles). Because of the triangular cross section of the male jaw base, it twists more easily than it bends. This torsional flexibility creates a safety system against overload that, at the same time, secures a firm grip on rivals. We found no structural mechanical function of the large teeth halfway along the male jaws. Therefore, it appears that the main purpose of these teeth is a further improvement of grip on rivals. PMID:26763329

Identification of the tracheal and laryngeal afferent neurones mediating cough in anaesthetized guinea-pigs

PubMed Central

Canning, Brendan J; Mazzone, Stuart B; Meeker, Sonya N; Mori, Nanako; Reynolds, Sandra M; Undem, Bradley J

2004-01-01

We have identified the tracheal and laryngeal afferent nerves regulating cough in anaesthetized guinea-pigs. Cough was evoked by electrical or mechanical stimulation of the tracheal or laryngeal mucosa, or by citric acid applied topically to the trachea or larynx. By contrast, neither capsaicin nor bradykinin challenges to the trachea or larynx evoked cough. Bradykinin and histamine administered intravenously also failed to evoke cough. Electrophysiological studies revealed that the majority of capsaicin-sensitive afferent neurones (both Aδ- and C-fibres) innervating the rostral trachea and larynx have their cell bodies in the jugular ganglia and project to the airways via the superior laryngeal nerves. Capsaicin-insensitive afferent neurones with cell bodies in the nodose ganglia projected to the rostral trachea and larynx via the recurrent laryngeal nerves. Severing the recurrent nerves abolished coughing evoked from the trachea and larynx whereas severing the superior laryngeal nerves was without effect on coughing. The data indicate that the tracheal and laryngeal afferent neurones regulating cough are polymodal Aδ-fibres that arise from the nodose ganglia. These afferent neurones are activated by punctate mechanical stimulation and acid but are unresponsive to capsaicin, bradykinin, smooth muscle contraction, longitudinal or transverse stretching of the airways, or distension. Comparing these physiological properties with those of intrapulmonary mechanoreceptors indicates that the afferent neurones mediating cough are quite distinct from the well-defined rapidly and slowly adapting stretch receptors innervating the airways and lungs. We propose that these airway afferent neurones represent a distinct subtype and that their primary function is regulation of the cough reflex. PMID:15004208

Dynactin-dependent cortical dynein and spherical spindle shape correlate temporally with meiotic spindle rotation in Caenorhabditis elegans

PubMed Central

Crowder, Marina E.; Flynn, Jonathan R.; McNally, Karen P.; Cortes, Daniel B.; Price, Kari L.; Kuehnert, Paul A.; Panzica, Michelle T.; Andaya, Armann; Leary, Julie A.; McNally, Francis J.

2015-01-01

Oocyte meiotic spindles orient with one pole juxtaposed to the cortex to facilitate extrusion of chromosomes into polar bodies. In Caenorhabditis elegans, these acentriolar spindles initially orient parallel to the cortex and then rotate to the perpendicular orientation. To understand the mechanism of spindle rotation, we characterized events that correlated temporally with rotation, including shortening of the spindle in the pole-to pole axis, which resulted in a nearly spherical spindle at rotation. By analyzing large spindles of polyploid C. elegans and a related nematode species, we found that spindle rotation initiated at a defined spherical shape rather than at a defined spindle length. In addition, dynein accumulated on the cortex just before rotation, and microtubules grew from the spindle with plus ends outward during rotation. Dynactin depletion prevented accumulation of dynein on the cortex and prevented spindle rotation independently of effects on spindle shape. These results support a cortical pulling model in which spindle shape might facilitate rotation because a sphere can rotate without deforming the adjacent elastic cytoplasm. We also present evidence that activation of spindle rotation is promoted by dephosphorylation of the basic domain of p150 dynactin. PMID:26133383

Nap sleep spindle correlates of intelligence.

PubMed

Ujma, Péter P; Bódizs, Róbert; Gombos, Ferenc; Stintzing, Johannes; Konrad, Boris N; Genzel, Lisa; Steiger, Axel; Dresler, Martin

2015-11-26

Sleep spindles are thalamocortical oscillations in non-rapid eye movement (NREM) sleep, that play an important role in sleep-related neuroplasticity and offline information processing. Several studies with full-night sleep recordings have reported a positive association between sleep spindles and fluid intelligence scores, however more recently it has been shown that only few sleep spindle measures correlate with intelligence in females, and none in males. Sleep spindle regulation underlies a circadian rhythm, however the association between spindles and intelligence has not been investigated in daytime nap sleep so far. In a sample of 86 healthy male human subjects, we investigated the correlation between fluid intelligence and sleep spindle parameters in an afternoon nap of 100 minutes. Mean sleep spindle length, amplitude and density were computed for each subject and for each derivation for both slow and fast spindles. A positive association was found between intelligence and slow spindle duration, but not any other sleep spindle parameter. As a positive correlation between intelligence and slow sleep spindle duration in full-night polysomnography has only been reported in females but not males, our results suggest that the association between intelligence and sleep spindles is more complex than previously assumed.

The role in masseter muscle activities of functionally elicited periodontal afferents from abutment teeth under overdentures.

PubMed

Mushimoto, E

1981-09-01

Five overdenture wearers with a small number of remaining natural teeth were selected to evaluate the effect of the afferent input from periodontal mechanoreceptors on masseter activity in man. As a control, a full denture wearer was included. The subjects were instructed to chew a piece of gum, and/or tap their teeth. Surface EmG from the bilateral masseter muscles were recorded and analysed. When functional pressure was applied, during chewing, to the abutment teeth as well as to mucosa through the denture base, masseter activities were encouraged. Following application of anaesthesia to the periodontal membrane of the abutments, masseter activities were reduced. The duration of the silent period (SP) appearing in the EMG burst following tooth tapping was significantly increased with root support compared to mucosal support only. With topical anaesthesia of the periodontal tissues, SP duration decreased significantly. In conclusion, it has become apparent that the pressure sensibility of abutment teeth bearing functional pressure under an overdenture base is capable of facilitating masseter activity, as one of the sources of oral sensory input during mastication.

Response of soleus Ia afferents to vibration in the presence of the tonic vibration reflex in the decerebrate cat.

PubMed

Clark, F J; Matthews, P B; Muir, R B

1981-02-01

1. Micro-electrode recordings were made from single Ia afferents in the intact nerve to the soleus muscle in the decerebrate cat while the muscle was developing a tonic vibration reflex. This was done in order to test how effectively the afferents were excited by the vibration, and to see if any insecurity in driving might be related to tremor.2. When the amplitude of vibration was 50 mum, and the tonic vibration reflex was reasonably well developed (> 1 N of active tension) all but one of forty-four Ia afferents were driven 1:1 by the vibration. Most were still driven by 30 mum vibration. The vibration, consisting of a train of discrete pulses at 150 Hz, was applied longitudinally in combination with a stretch of 1 mm to make the muscle taut.3. If the reflex was poorly developed (active tension < 1 N) the driving was on average less secure. However, fourteen of eighteen afferents then studied were still driven 1:1 by 50 mum vibration. The lower level of excitation by vibration was thought to be due to a deficiency of spontaneous fusimotor activity, because stroking the cat's tail or other similar gentle manipulation led each of the three misbehaving afferents so tested to be driven securely by 50 mum vibration; at the same time the reflex tension increased.4. Additional, indirect evidence favouring widespread security of Ia driving by 50 mum vibration in the presence of the reflex was obtained by modulating the amplitude of the 150 Hz vibration with a 7-10 Hz square wave and detecting any tension fluctuations at that frequency by spectral analysis. Small degrees of modulation (e.g. < 10%) produced little if any effect, although larger depths of modulation had a powerful action.5. When the amplitude of vibration was reduced to permit insecure driving but still to elicit a reflex response, the fluctuations in Ia firing pattern were unlike those previously seen in the de-efferented muscle. Spectral analysis showed that these firing fluctuations bore a general

Response of soleus Ia afferents to vibration in the presence of the tonic vibration reflex in the decerebrate cat

PubMed Central

Clark, F. J.; Matthews, P. B. C.; Muir, R. B.

1981-01-01

1. Micro-electrode recordings were made from single Ia afferents in the intact nerve to the soleus muscle in the decerebrate cat while the muscle was developing a tonic vibration reflex. This was done in order to test how effectively the afferents were excited by the vibration, and to see if any insecurity in driving might be related to tremor. 2. When the amplitude of vibration was 50 μm, and the tonic vibration reflex was reasonably well developed (> 1 N of active tension) all but one of forty-four Ia afferents were driven 1:1 by the vibration. Most were still driven by 30 μm vibration. The vibration, consisting of a train of discrete pulses at 150 Hz, was applied longitudinally in combination with a stretch of 1 mm to make the muscle taut. 3. If the reflex was poorly developed (active tension < 1 N) the driving was on average less secure. However, fourteen of eighteen afferents then studied were still driven 1:1 by 50 μm vibration. The lower level of excitation by vibration was thought to be due to a deficiency of spontaneous fusimotor activity, because stroking the cat's tail or other similar gentle manipulation led each of the three misbehaving afferents so tested to be driven securely by 50 μm vibration; at the same time the reflex tension increased. 4. Additional, indirect evidence favouring widespread security of Ia driving by 50 μm vibration in the presence of the reflex was obtained by modulating the amplitude of the 150 Hz vibration with a 7-10 Hz square wave and detecting any tension fluctuations at that frequency by spectral analysis. Small degrees of modulation (e.g. < 10%) produced little if any effect, although larger depths of modulation had a powerful action. 5. When the amplitude of vibration was reduced to permit insecure driving but still to elicit a reflex response, the fluctuations in Ia firing pattern were unlike those previously seen in the de-efferented muscle. Spectral analysis showed that these firing fluctuations bore a general

Finite element modelling predicts changes in joint shape and cell behaviour due to loss of muscle strain in jaw development

PubMed Central

Brunt, Lucy H.; Norton, Joanna L.; Bright, Jen A.; Rayfield, Emily J.; Hammond, Chrissy L.

2015-01-01

Abnormal joint morphogenesis is linked to clinical conditions such as Developmental Dysplasia of the Hip (DDH) and to osteoarthritis (OA). Muscle activity is known to be important during the developmental process of joint morphogenesis. However, less is known about how this mechanical stimulus affects the behaviour of joint cells to generate altered morphology. Using zebrafish, in which we can image all joint musculoskeletal tissues at high resolution, we show that removal of muscle activity through anaesthetisation or genetic manipulation causes a change to the shape of the joint between the Meckel's cartilage and Palatoquadrate (the jaw joint), such that the joint develops asymmetrically leading to an overlap of the cartilage elements on the medial side which inhibits normal joint function. We identify the time during which muscle activity is critical to produce a normal joint. Using Finite Element Analysis (FEA), to model the strains exerted by muscle on the skeletal elements, we identify that minimum principal strains are located at the medial region of the joint and interzone during mouth opening. Then, by studying the cells immediately proximal to the joint, we demonstrate that biomechanical strain regulates cell orientation within the developing joint, such that when muscle-induced strain is removed, cells on the medial side of the joint notably change their orientation. Together, these data show that biomechanical forces are required to establish symmetry in the joint during development. PMID:26253758

Finite element modelling predicts changes in joint shape and cell behaviour due to loss of muscle strain in jaw development.

PubMed

Brunt, Lucy H; Norton, Joanna L; Bright, Jen A; Rayfield, Emily J; Hammond, Chrissy L

2015-09-18

Abnormal joint morphogenesis is linked to clinical conditions such as Developmental Dysplasia of the Hip (DDH) and to osteoarthritis (OA). Muscle activity is known to be important during the developmental process of joint morphogenesis. However, less is known about how this mechanical stimulus affects the behaviour of joint cells to generate altered morphology. Using zebrafish, in which we can image all joint musculoskeletal tissues at high resolution, we show that removal of muscle activity through anaesthetisation or genetic manipulation causes a change to the shape of the joint between the Meckel's cartilage and Palatoquadrate (the jaw joint), such that the joint develops asymmetrically leading to an overlap of the cartilage elements on the medial side which inhibits normal joint function. We identify the time during which muscle activity is critical to produce a normal joint. Using Finite Element Analysis (FEA), to model the strains exerted by muscle on the skeletal elements, we identify that minimum principal strains are located at the medial region of the joint and interzone during mouth opening. Then, by studying the cells immediately proximal to the joint, we demonstrate that biomechanical strain regulates cell orientation within the developing joint, such that when muscle-induced strain is removed, cells on the medial side of the joint notably change their orientation. Together, these data show that biomechanical forces are required to establish symmetry in the joint during development. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Influence of muscle pain tolerance on muscle pain threshold in experimental tooth clenching in man.

PubMed

Christensen, L V

1979-07-01

Ten adults and ten children exercised maximal voluntary tooth clenching until pains appeared in the jaw muscles, i.e. the muscle pain threshold of tooth clenching was determined. Subsequently, the subjects were instructed to exercise tooth clenching until they were forced to stop because of intolerable pains and exhaustion of the contracting muscles, i.e. the muscle pain tolerance of tooth clenching was recorded, and during these bouts of clenching the pain tolerance of tooth clenching was recorded, and during these bouts of clenching the pain threshold was also determined. In adults, determination of the pain tolerance decreased the pain threshold by 19%, and in children it either decreased the pain threshold by 20% or increased it by 56%. It is proposed to introduce the muscle pain tolerance of tooth clenching as an adjunct in the clinical examination of cases of facial pains presumed to originate from the jaw muscles, but the test should be interpreted with caution.

The spindle protein CHICA mediates localization of the chromokinesin Kid to the mitotic spindle.

PubMed

Santamaria, Anna; Nagel, Susanna; Sillje, Herman H W; Nigg, Erich A

2008-05-20

Microtubule-based motor proteins provide essential forces for bipolar organization of spindle microtubules and chromosome movement, prerequisites of chromosome segregation during the cell cycle. Here, we describe the functional characterization of a novel spindle protein, termed "CHICA," that was originally identified in a proteomic survey of the human spindle apparatus [1]. We show that CHICA localizes to the mitotic spindle and is both upregulated and phosphorylated during mitosis. CHICA-depleted cells form shorter spindles and fail to organize a proper metaphase plate, highly reminiscent of the phenotype observed upon depletion of the chromokinesin Kid, a key mediator of polar ejection forces [2-6]. We further show that CHICA coimmunoprecipitates with Kid and is required for the spindle localization of Kid without affecting its chromosome association. Moreover, upon depletion of either CHICA or Kid (or both proteins simultaneously), chromosomes collapse onto the poles of monastrol-induced monopolar spindles. We conclude that CHICA represents a novel interaction partner of the chromokinesin Kid that is required for the generation of polar ejection forces and chromosome congression.

Severe hypoxia affects exercise performance independently of afferent feedback and peripheral fatigue.

PubMed

Millet, Guillaume Y; Muthalib, Makii; Jubeau, Marc; Laursen, Paul B; Nosaka, Kazunori

2012-04-01

To test the hypothesis that hypoxia centrally affects performance independently of afferent feedback and peripheral fatigue, we conducted two experiments under complete vascular occlusion of the exercising muscle under different systemic O(2) environmental conditions. In experiment 1, 12 subjects performed repeated submaximal isometric contractions of the elbow flexor to exhaustion (RCTE) with inspired O(2) fraction fixed at 9% (severe hypoxia, SevHyp), 14% (moderate hypoxia, ModHyp), 21% (normoxia, Norm), or 30% (hyperoxia, Hyper). The number of contractions (performance), muscle (biceps brachii), and prefrontal near-infrared spectroscopy (NIRS) parameters and high-frequency paired-pulse (PS100) evoked responses to electrical muscle stimulation were monitored. In experiment 2, 10 subjects performed another RCTE in SevHyp and Norm conditions in which the number of contractions, biceps brachii electromyography responses to electrical nerve stimulation (M wave), and transcranial magnetic stimulation responses (motor-evoked potentials, MEP, and cortical silent period, CSP) were recorded. Performance during RCTE was significantly reduced by 10-15% in SevHyp (arterial O(2) saturation, SpO(2) = ∼75%) compared with ModHyp (SpO(2) = ∼90%) or Norm/Hyper (SpO(2) > 97%). Performance reduction in SevHyp occurred despite similar 1) metabolic (muscle NIRS parameters) and functional (changes in PS100 and M wave) muscle states and 2) MEP and CSP responses, suggesting comparable corticospinal excitability and spinal and cortical inhibition between SevHyp and Norm. It is concluded that, in SevHyp, performance and central drive can be altered independently of afferent feedback and peripheral fatigue. It is concluded that submaximal performance in SevHyp is partly reduced by a mechanism related directly to brain oxygenation.

Trigeminal and telencephalic projections to jaw and other upper vocal tract premotor neurons in songbirds: sensorimotor circuitry for beak movements during singing.

PubMed

Wild, J M; Krützfeldt, N E O

2012-02-15

During singing in songbirds, the extent of beak opening, like the extent of mouth opening in human singers, is partially correlated with the fundamental frequency of the sounds emitted. Since song in songbirds is under the control of "the song system" (a collection of interconnected forebrain nuclei dedicated to the learning and production of song), it might be expected that beak movements during singing would also be controlled by this system. However, direct neural connections between the telencephalic output of the song system and beak muscle motor neurons in the brainstem are conspicuous by their absence, leaving unresolved the question of how beak movements are affected during singing. By using standard tract tracing methods, we sought to answer this question by defining beak premotor neurons and examining their afferent projections. In the caudal medulla, jaw premotor cell bodies were located adjacent to the terminal field of the output of the song system, into which many premotor neurons extended their dendrites. The premotor neurons also received a novel input from the trigeminal ganglion and an overlapping input from a lateral arcopallial component of a trigeminal sensorimotor circuit that traverses the forebrain. The ganglionic input in songbirds, which is not present in doves and pigeons that vocalize with a closed beak, may modulate the activity of beak premotor neurons in concert with the output of the song system. These inputs to jaw premotor neurons could, together, affect beak movements as a means of modulating filter properties of the upper vocal tract during singing. Copyright © 2011 Wiley-Liss, Inc.

Trigeminal and Telencephalic Projections to Jaw and Other Upper Vocal Tract Premotor Neurons in Songbirds: Sensorimotor Circuitry for Beak Movements During Singing

PubMed Central

Wild, J.M.; Krützfeldt, N.E.O.

2014-01-01

During singing in songbirds, the extent of beak opening, like the extent of mouth opening in human singers, is partially correlated with the fundamental frequency of the sounds emitted. Since song in songbirds is under the control of “the song system” (a collection of interconnected forebrain nuclei dedicated to the learning and production of song), it might be expected that beak movements during singing would also be controlled by this system. However, direct neural connections between the telencephalic output of the song system and beak muscle motor neurons in the brainstem are conspicuous by their absence, leaving unresolved the question of how beak movements are affected during singing. By using standard tract tracing methods, we sought to answer this question by defining beak premotor neurons and examining their afferent projections. In the caudal medulla, jaw premotor cell bodies were located adjacent to the terminal field of the output of the song system, into which many premotor neurons extended their dendrites. The premotor neurons also received a novel input from the trigeminal ganglion and an overlapping input from a lateral arcopallial component of a trigeminal sensorimotor circuit that traverses the forebrain. The ganglionic input in songbirds, which is not present in doves and pigeons that vocalize with a closed beak, may modulate the activity of beak premotor neurons in concert with the output of the song system. These inputs to jaw premotor neurons could, together, affect beak movements as a means of modulating filter properties of the upper vocal tract during singing. PMID:21858818

Acylcarnitines as markers of exercise-associated fuel partitioning, xenometabolism, and potential signals to muscle afferent neurons.

PubMed

Zhang, Jie; Light, Alan R; Hoppel, Charles L; Campbell, Caitlin; Chandler, Carol J; Burnett, Dustin J; Souza, Elaine C; Casazza, Gretchen A; Hughen, Ronald W; Keim, Nancy L; Newman, John W; Hunter, Gary R; Fernandez, Jose R; Garvey, W Timothy; Harper, Mary-Ellen; Fiehn, Oliver; Adams, Sean H

2017-01-01

that a weight-loss/fitness intervention alters plasma xenometabolites [i.e. cis-3,4-methylene-heptanoylcarnitine and γ-butyrobetaine (a co-metabolite possibly derived in part from gut bacteria)], suggesting that host metabolic health regulated gut microbe metabolism. Finally, we considered whether acylcarnitine metabolites signal to muscle-innervating afferents; palmitoylcarnitine at concentrations as low as 1-10 μm activated a subset (∼2.5-5%) of these neurons ex vivo. This supports the hypothesis that in addition to tracking exercise-associated shifts in fuel metabolism, muscle acylcarnitines act as signals of exertion to short-loop somatosensory-motor circuits or to the brain. © 2016 The Authors. Experimental Physiology © 2016 The Physiological Society.

Jaw and Order

ERIC Educational Resources Information Center

Mooshammer, Christine; Hoole, Philip; Geumann, Anja

2007-01-01

It is well-accepted that the jaw plays an active role in influencing vowel height. The general aim of the current study is to further investigate the extent to which the jaw is active in producing consonantal distinctions, with specific focus on coronal consonants. Therefore, tongue tip and jaw positions are compared for the German coronal…

The jaw is a second-class lever in Pedetes capensis (Rodentia: Pedetidae)

PubMed Central

2017-01-01

The mammalian jaw is often modelled as a third-class lever for the purposes of biomechanical analyses, owing to the position of the resultant muscle force between the jaw joint and the teeth. However, it has been proposed that in some rodents the jaws operate as a second-class lever during distal molar bites, owing to the rostral position of the masticatory musculature. In particular, the infraorbital portion of the zygomatico-mandibularis (IOZM) has been suggested to be of major importance in converting the masticatory system from a third-class to a second-class lever. The presence of the IOZM is diagnostic of the hystricomorph rodents, and is particularly well-developed in Pedetes capensis, the South African springhare. In this study, finite element analysis (FEA) was used to assess the lever mechanics of the springhare masticatory system, and to determine the function of the IOZM. An FE model of the skull of P. capensis was constructed and loaded with all masticatory muscles, and then solved for biting at each tooth in turn. Further load cases were created in which each masticatory muscle was removed in turn. The analyses showed that the mechanical advantage of the springhare jaws was above one at all molar bites and very close to one during the premolar bite. Removing the IOZM or masseter caused a drop in mechanical advantage at all bites, but affected strain patterns and cranial deformation very little. Removing the ZM had only a small effect on mechanical advantage, but produced a substantial reduction in strain and deformation across the skull. It was concluded that the masticatory system of P. capensis acts as a second class lever during bites along almost the entire cheek tooth row. The IOZM is clearly a major contributor to this effect, but the masseter also has a part to play. The benefit of the IOZM is that it adds force without substantially contributing to strain or deformation of the skull. This may help explain why the hystricomorphous morphology

Tempol prevents altered K(+) channel regulation of afferent arteriolar tone in diabetic rat kidney.

PubMed

Troncoso Brindeiro, Carmen M; Lane, Pascale H; Carmines, Pamela K

2012-03-01

Experiments were performed to test the hypothesis that oxidative stress underlies the enhanced tonic dilator impact of inward-rectifier K(+) channels on renal afferent arterioles of rats with streptozotocin-induced diabetes mellitus. Sham and diabetic rats were left untreated or provided Tempol in their drinking water for 26±1 days, after which afferent arteriolar lumen diameter and its responsiveness to K(+) channel blockade were measured using the in vitro blood-perfused juxtamedullary nephron technique. Afferent diameter averaged 19.4±0.8 μm in sham rats and 24.4±0.8 μm in diabetic rats (P<0.05). The decrease in diameter evoked by Ba(2+) (inward-rectifier K(+) channel blocker) was 3 times greater in diabetic rats than in sham rats. Glibenclamide (K(ATP) channel blocker) and tertiapin-Q (Kir1.1/Kir3.x channel blocker) decreased afferent diameter in diabetic rats but had no effect on arterioles from sham rats. Chronic Tempol treatment prevented diabetes mellitus-induced increases in both renal vascular dihydroethidium staining and baseline afferent arteriolar diameter. Moreover, Tempol prevented the exaggeration of afferent arteriolar responses to Ba(2+), tertiapin-Q, and glibenclamide otherwise evident in diabetic rats. Preglomerular microvascular smooth muscle cells expressed mRNA encoding Kir1.1, Kir2.1, and Kir6.1. Neither diabetes mellitus nor Tempol altered Kir1.1, Kir2.1, Kir6.1, or SUR2B protein levels in renal cortical microvessels. To the extent that the effects of Tempol reflect its antioxidant actions, our observations indicate that oxidative stress contributes to the exaggerated impact of Kir1.1, Kir2.1, and K(ATP) channels on afferent arteriolar tone during diabetes mellitus and that this phenomenon involves posttranslational modulation of channel function.

Adaptation of rat jaw muscle fibers in postnatal development with a different food consistency: an immunohistochemical and electromyographic study.

PubMed

Kawai, Nobuhiko; Sano, Ryota; Korfage, Joannes A M; Nakamura, Saika; Kinouchi, Nao; Kawakami, Emi; Tanne, Kazuo; Langenbach, Geerling E J; Tanaka, Eiji

2010-06-01

.05). The cross-sectional area of type IIX and type IIB fibers of the superficial masseter muscle was significantly smaller in the soft-diet group than in the hard-diet group (P < 0.05). There was no difference in the muscle fiber composition and the cross-sectional area of the anterior belly of the digastric and anterior temporalis muscles. In conclusion, for the jaw muscles of male rats reared on a soft diet, the slow-to-fast transition of muscle fiber was shown in only the superficial masseter muscle. Therefore, the reduction in the amount of powerful muscle contractions could be important for the slow-to-fast transition of the myosin heavy chain isoform in muscle fibers.

Mechanisms of plant spindle formation.

PubMed

Zhang, Han; Dawe, R Kelly

2011-04-01

In eukaryotes, the formation of a bipolar spindle is necessary for the equal segregation of chromosomes to daughter cells. Chromosomes, microtubules and kinetochores all contribute to spindle morphogenesis and have important roles during mitosis. A unique property of flowering plant cells is that they entirely lack centrosomes, which in animals have a major role in spindle formation. The absence of these important structures suggests that plants have evolved novel mechanisms to assure chromosome segregation. In this review, we highlight some of the recent studies on plant mitosis and argue that plants utilize a variation of "spindle self-organization" that takes advantage of the early polarity of plant cells and accentuates the role of kinetochores in stabilizing the spindle midzone in prometaphase.

Synchronization and Propagation of Global Sleep Spindles

PubMed Central

de Souza, Rafael Toledo Fernandes; Gerhardt, Günther Johannes Lewczuk; Schönwald, Suzana Veiga; Rybarczyk-Filho, José Luiz; Lemke, Ney

2016-01-01

Sleep spindles occur thousands of times during normal sleep and can be easily detected by visual inspection of EEG signals. These characteristics make spindles one of the most studied EEG structures in mammalian sleep. In this work we considered global spindles, which are spindles that are observed simultaneously in all EEG channels. We propose a methodology that investigates both the signal envelope and phase/frequency of each global spindle. By analysing the global spindle phase we showed that 90% of spindles synchronize with an average latency time of 0.1 s. We also measured the frequency modulation (chirp) of global spindles and found that global spindle chirp and synchronization are not correlated. By investigating the signal envelopes and implementing a homogeneous and isotropic propagation model, we could estimate both the signal origin and velocity in global spindles. Our results indicate that this simple and non-invasive approach could determine with reasonable precision the spindle origin, and allowed us to estimate a signal speed of 0.12 m/s. Finally, we consider whether synchronization might be useful as a non-invasive diagnostic tool. PMID:26963102

Microneurography as a tool in clinical neurophysiology to investigate peripheral neural traffic in humans.

PubMed

Mano, Tadaaki; Iwase, Satoshi; Toma, Shinobu

2006-11-01

Microneurography is a method using metal microelectrodes to investigate directly identified neural traffic in myelinated as well as unmyelinated efferent and afferent nerves leading to and coming from muscle and skin in human peripheral nerves in situ. The present paper reviews how this technique has been used in clinical neurophysiology to elucidate the neural mechanisms of autonomic regulation, motor control and sensory functions in humans under physiological and pathological conditions. Microneurography is particularly important to investigate efferent and afferent neural traffic in unmyelinated C fibers. The recording of efferent discharges in postganglionic sympathetic C efferent fibers innervating muscle and skin (muscle sympathetic nerve activity; MSNA and skin sympathetic nerve activity; SSNA) provides direct information about neural control of autonomic effector organs including blood vessels and sweat glands. Sympathetic microneurography has become a potent tool to reveal neural functions and dysfunctions concerning blood pressure control and thermoregulation. This recording has been used not only in wake conditions but also in sleep to investigate changes in sympathetic neural traffic during sleep and sleep-related events such as sleep apnea. The same recording was also successfully carried out by astronauts during spaceflight. Recordings of afferent discharges from muscle mechanoreceptors have been used to understand the mechanisms of motor control. Muscle spindle afferent information is particularly important for the control of fine precise movements. It may also play important roles to predict behavior outcomes during learning of a motor task. Recordings of discharges in myelinated afferent fibers from skin mechanoreceptors have provided not only objective information about mechanoreceptive cutaneous sensation but also the roles of these signals in fine motor control. Unmyelinated mechanoreceptive afferent discharges from hairy skin seem to be

Model-based sensorimotor integration for multi-joint control: development of a virtual arm model.

PubMed

Song, D; Lan, N; Loeb, G E; Gordon, J

2008-06-01

An integrated, sensorimotor virtual arm (VA) model has been developed and validated for simulation studies of control of human arm movements. Realistic anatomical features of shoulder, elbow and forearm joints were captured with a graphic modeling environment, SIMM. The model included 15 musculotendon elements acting at the shoulder, elbow and forearm. Muscle actions on joints were evaluated by SIMM generated moment arms that were matched to experimentally measured profiles. The Virtual Muscle (VM) model contained appropriate admixture of slow and fast twitch fibers with realistic physiological properties for force production. A realistic spindle model was embedded in each VM with inputs of fascicle length, gamma static (gamma(stat)) and dynamic (gamma(dyn)) controls and outputs of primary (I(a)) and secondary (II) afferents. A piecewise linear model of Golgi Tendon Organ (GTO) represented the ensemble sampling (I(b)) of the total muscle force at the tendon. All model components were integrated into a Simulink block using a special software tool. The complete VA model was validated with open-loop simulation at discrete hand positions within the full range of alpha and gamma drives to extrafusal and intrafusal muscle fibers. The model behaviors were consistent with a wide variety of physiological phenomena. Spindle afferents were effectively modulated by fusimotor drives and hand positions of the arm. These simulations validated the VA model as a computational tool for studying arm movement control. The VA model is available to researchers at website http://pt.usc.edu/cel .

Characterization of Topographically Specific Sleep Spindles in Mice

PubMed Central

Kim, Dongwook; Hwang, Eunjin; Lee, Mina; Sung, Hokun; Choi, Jee Hyun

2015-01-01

Study Objective: Sleep spindles in humans have been classified as slow anterior and fast posterior spindles; recent findings indicate that their profiles differ according to pharmacology, pathology, and function. However, little is known about the generation mechanisms within the thalamocortical system for different types of spindles. In this study, we aim to investigate the electrophysiological behaviors of the topographically distinctive spindles within the thalamocortical system by applying high-density EEG and simultaneous thalamic LFP recordings in mice. Design: 32-channel extracranial EEG and 2-channel thalamic LFP were recorded simultaneously in freely behaving mice to acquire spindles during spontaneous sleep. Subjects: Hybrid F1 male mice of C57BL/6J and 129S4/svJae. Measurements and Results: Spindle events in each channel were detected by spindle detection algorithm, and then a cluster analysis was applied to classify the topographically distinctive spindles. All sleep spindles were successfully classified into 3 groups: anterior, posterior, and global spindles. Each spindle type showed distinct thalamocortical activity patterns regarding the extent of similarity, phase synchrony, and time lags between cortical and thalamic areas during spindle oscillation. We also found that sleep slow waves were likely to associate with all types of sleep spindles, but also that the ongoing cortical decruitment/recruitment dynamics before the onset of spindles and their relationship with spindle generation were also variable, depending on the spindle types. Conclusion: Topographically specific sleep spindles show distinctive thalamocortical network behaviors. Citation: Kim D, Hwang E, Lee M, Sung H, Choi JH. Characterization of topographically specific sleep spindles in mice. SLEEP 2015;38(1):85–96. PMID:25325451

Position sense at the human elbow joint measured by arm matching or pointing.

PubMed

Tsay, Anthony; Allen, Trevor J; Proske, Uwe

2016-10-01

Position sense at the human elbow joint has traditionally been measured in blindfolded subjects using a forearm matching task. Here we compare position errors in a matching task with errors generated when the subject uses a pointer to indicate the position of a hidden arm. Evidence from muscle vibration during forearm matching supports a role for muscle spindles in position sense. We have recently shown using vibration, as well as muscle conditioning, which takes advantage of muscle's thixotropic property, that position errors generated in a forearm pointing task were not consistent with a role by muscle spindles. In the present study we have used a form of muscle conditioning, where elbow muscles are co-contracted at the test angle, to further explore differences in position sense measured by matching and pointing. For fourteen subjects, in a matching task where the reference arm had elbow flexor and extensor muscles contracted at the test angle and the indicator arm had its flexors conditioned at 90°, matching errors lay in the direction of flexion by 6.2°. After the same conditioning of the reference arm and extension conditioning of the indicator at 0°, matching errors lay in the direction of extension (5.7°). These errors were consistent with predictions based on a role by muscle spindles in determining forearm matching outcomes. In the pointing task subjects moved a pointer to align it with the perceived position of the hidden arm. After conditioning of the reference arm as before, pointing errors all lay in a more extended direction than the actual position of the arm by 2.9°-7.3°, a distribution not consistent with a role by muscle spindles. We propose that in pointing muscle spindles do not play the major role in signalling limb position that they do in matching, but that other sources of sensory input should be given consideration, including afferents from skin and joint.

Differential Diagnosis of Benign Spindle Cell Lesions.

PubMed

Magro, Gaetano

2018-03-01

Spindle cell lesions of the breast cover a wide spectrum of diseases ranging from reactive tumor-like lesions to high-grade malignant tumors. The recognition of the benign spindle cell tumor-like lesions (nodular fasciitis; reactive spindle cell nodule after biopsy, inflammatory pseudotumor/inflammatory myofibroblastic tumor; fascicular variant of pseudoangiomatous stromal hyperplasia) and tumors (myofibroblastoma, benign fibroblastic spindle cell tumor, leiomyoma, schwannoma, spindle cell lipoma, solitary fibrous tumor, myxoma) is crucial to avoid confusion with morphologically similar but more aggressive bland-appearing spindle cell tumors, such as desmoid-type fibromatosis, low-grade (fibromatosis-like) spindle cell carcinoma, low-grade fibrosarcoma/myofibroblastic sarcoma and dermatofibrosarcoma protuberans. Copyright © 2017 Elsevier Inc. All rights reserved.

Searching for proprioceptors in human facial muscles.

PubMed

Cobo, Juan L; Abbate, Francesco; de Vicente, Juan C; Cobo, Juan; Vega, José A

2017-02-15

The human craniofacial muscles innervated by the facial nerve typically lack muscle spindles. However these muscles have proprioception that participates in the coordination of facial movements. A functional substitution of facial proprioceptors by cutaneous mechanoreceptors has been proposed but at present this alternative has not been demonstrated. Here we have investigated whether other kinds of sensory structures are present in two human facial muscles (zygomatic major and buccal). Human checks were removed from Spanish cadavers, and processed for immunohistochemical detection of nerve fibers (neurofilament proteins and S100 protein) and two putative mechanoproteins (acid-sensing ion channel 2 and transient receptor potential vanilloid 4) associated with mechanosensing. Nerves of different calibers were found in the connective septa and within the muscle itself. In all the muscles analysed, capsular corpuscle-like structures resembling elongated or round Ruffini-like corpuscles were observed. Moreover the axon profiles within these structures displayed immunoreactivity for both putative mechanoproteins. The present results demonstrate the presence of sensory structures in facial muscles that can substitute for typical muscle spindles as the source of facial proprioception. Copyright © 2017 Elsevier B.V. All rights reserved.

Functional Morphology of Eunicidan (Polychaeta) Jaws

NASA Astrophysics Data System (ADS)

Clemo, W. C.; Dorgan, K. M.

2016-02-01

Polychaetes exhibit diverse feeding strategies and diets, with some species possessing hardened teeth or jaws of varying complexity. Species in the order Eunicida have complex, rigidly articulated jaws consisting of multiple pairs of maxillae and a pair of mandibles. While all Eunicida possess this general jaw structure, a number of characteristics of the jaw parts vary considerably among families. These differences, described for fossilized and extant species' jaws, were used to infer evolutionary relationships, but current phylogeny shows that jaw structures that are similar among several families are convergent. Little has been done, however, to relate jaw functional morphology and feeding behavior to diet. To explore these relationships, we compared the jaw kinematics of two taxa with similar but evolutionarily convergent jaw structures: Diopatra (Onuphidae) and Lumbrineris (Lumbrineridae). Diopatra species are tube-dwelling and predominantly herbivorous, whereas Lumbrineris species are burrowing carnivores. Jaw kinematics were observed and analyzed by filming individuals biting or feeding and tracking tooth movements in videos. Differences in jaw structure and kinematics between Diopatra and Lumbrineris can be interpreted to be consistent with their differences in diet. Relating jaw morphology to diet would provide insight into early annelid communities by linking fossil teeth (scolecodonts) to the ecological roles of extant species with similar morphologies.

Monosynaptic Ia projections from intrinsic hand muscles to forearm motoneurones in humans.

PubMed

Marchand-Pauvert, V; Nicolas, G; Pierrot-Deseilligny, E

2000-05-15

Heteronymous Ia excitatory projections from intrinsic hand muscles to human forearm motoneurones (MNs) were investigated. Changes in firing probability of single motor units (MUs) in the flexor carpi radialis (FCR), flexor carpi ulnaris (FCU), flexor digitorum superficialis (FDS), extensor carpi radialis (ECR), extensor carpi ulnaris (ECU) and extensor digitorum communis (EDC) were studied after electrical stimuli were applied to the median and ulnar nerve at wrist level and to the corresponding homonymous nerve at elbow level. Homonymous facilitation, occurring at the same latency as the H reflex, and therefore attributed to monosynaptic Ia EPSPs, was found in all the sampled units. In many MUs an early facilitation was also evoked by heteronymous low-threshold afferents from intrinsic hand muscles. The low threshold (between 0.5 and 0.6 times motor threshold (MT)) and the inability of a pure cutaneous stimulation to reproduce this effect indicate that it is due to stimulation of group I muscle afferents. Evidence for a similar central delay (monosynaptic) in heteronymous as in homonymous pathways was accepted when the difference in latencies of the homonymous and heteronymous peaks did not differ from the estimated supplementary afferent conduction time from wrist to elbow level by more than 0.5 ms (conduction velocity in the fastest Ia afferents between wrist and elbow levels being equal to 69 m s-1). A statistically significant heteronymous monosynaptic Ia excitation from intrinsic hand muscles supplied by both median and ulnar nerves was found in MUs belonging to all forearm motor nuclei tested (although not in ECU MUs after ulnar stimulation). It was, however, more often found in flexors than in extensors, in wrist than in finger muscles and in muscles operating in the radial than in the ulnar side. It is argued that the connections of Ia afferents from intrinsic hand muscles to forearm MNs, which are stronger and more widely distributed than in the cat

C-tactile afferent stimulating touch carries a positive affective value.

PubMed

Pawling, Ralph; Cannon, Peter R; McGlone, Francis P; Walker, Susannah C

2017-01-01

The rewarding sensation of touch in affiliative interactions is hypothesized to be underpinned by a specialized system of nerve fibers called C-Tactile afferents (CTs), which respond optimally to slowly moving, gentle touch, typical of a caress. However, empirical evidence to support the theory that CTs encode socially relevant, rewarding tactile information in humans is currently limited. While in healthy participants, touch applied at CT optimal velocities (1-10cm/sec) is reliably rated as subjectively pleasant, neuronopathy patients lacking large myelinated afferents, but with intact C-fibres, report that the conscious sensation elicited by stimulation of CTs is rather vague. Given this weak perceptual impact the value of self-report measures for assessing the specific affective value of CT activating touch appears limited. Therefore, we combined subjective ratings of touch pleasantness with implicit measures of affective state (facial electromyography) and autonomic arousal (heart rate) to determine whether CT activation carries a positive affective value. We recorded the activity of two key emotion-relevant facial muscle sites (zygomaticus major-smile muscle, positive affect & corrugator supercilii-frown muscle, negative affect) while participants evaluated the pleasantness of experimenter administered stroking touch, delivered using a soft brush, at two velocities (CT optimal 3cm/sec & CT non-optimal 30cm/sec), on two skin sites (CT innervated forearm & non-CT innervated palm). On both sites, 3cm/sec stroking touch was rated as more pleasant and produced greater heart rate deceleration than 30cm/sec stimulation. However, neither self-report ratings nor heart rate responses discriminated stimulation on the CT innervated arm from stroking of the non-CT innervated palm. In contrast, significantly greater activation of the zygomaticus major (smiling muscle) was seen specifically to CT optimal, 3cm/sec, stroking on the forearm in comparison to all other stimuli

Corrective Jaw Surgery

MedlinePlus Videos and Cool Tools

... Jaw Surgery Download Download the ebook for further information Corrective jaw, or orthognathic surgery is performed by ... your treatment. Correction of Common Dentofacial Deformities ​ ​ The information provided here is not intended as a substitute ...

Effects of aging and sarcopenia on tongue pressure and jaw-opening force.

PubMed

Machida, Nami; Tohara, Haruka; Hara, Koji; Kumakura, Ayano; Wakasugi, Yoko; Nakane, Ayako; Minakuchi, Shunsuke

2017-02-01

Aging and sarcopenia reduce not only body strength, but also the strength of swallowing muscles. We examined how aging and sarcopenia affect tongue pressure and jaw-opening force. A total of 97 older adults (97 men, mean age 78.5 ± 6.6 years; 100 women, mean age 77.8 ± 6.2 years) were enrolled. Classification of sarcopenia was based on the Criteria of Asian Working Group for Sarcopenia. To investigate which variable between aging and sarcopenia was a significant independent variable on tongue pressure and jaw-opening force, multivariate linear regression analysis was carried out. The mean tongue pressure was 26.3 ± 7.8 kPa in men and 24.6 ± 7.2 kPa in women. The mean jaw-opening force was 6.3 ± 1.6 kg in men and 5.2 ± 1.3 kg in women. Tongue pressure in men, aging and sarcopenia were significant independent variables, whereas only sarcopenia was a significant independent variable in women. Jaw-opening force in men and sarcopenia were significant independent variables, whereas neither aging nor sarcopenia were significant independent variables in women. We found different characteristics in the effects of aging and sarcopenia based on site and sex. We suggested that aging decreased tongue pressure more than jaw-opening force, and affected men more than women. Sarcopenia affected tongue pressure and jaw-opening force, with the exception of jaw-opening force in women. Considering these characteristics is useful to predict the decline of swallowing function, and provide appropriate interventions preventing dysphagia. Geriatr Gerontol Int 2017; 17: 295-301. © 2016 Japan Geriatrics Society.

Modulation of synaptic transmission from segmental afferents by spontaneous activity of dorsal horn spinal neurones in the cat.

PubMed

Manjarrez, E; Rojas-Piloni, J G; Jimenez, I; Rudomin, P

2000-12-01

We examined, in the anaesthetised cat, the influence of the neuronal ensembles producing spontaneous negative cord dorsum potentials (nCDPs) on segmental pathways mediating primary afferent depolarisation (PAD) of cutaneous and group I muscle afferents and on Ia monosynaptic activation of spinal motoneurones. The intraspinal distribution of the field potentials associated with the spontaneous nCDPs indicated that the neuronal ensembles involved in the generation of these potentials were located in the dorsal horn of lumbar segments, in the same region of termination of low-threshold cutaneous afferents. During the occurrence of spontaneous nCDPs, transmission from low-threshold cutaneous afferents to second order neurones in laminae III-VI, as well as transmission along pathways mediating PAD of cutaneous and Ib afferents, was facilitated. PAD of Ia afferents was instead inhibited. Monosynaptic reflexes of flexors and extensors were facilitated during the spontaneous nCDPs. The magnitude of the facilitation was proportional to the amplitude of the 'conditioning' spontaneous nCDPs. This led to a high positive correlation between amplitude fluctuations of spontaneous nCDPs and fluctuations of monosynaptic reflexes. Stimulation of low-threshold cutaneous afferents transiently reduced the probability of occurrence of spontaneous nCDPs as well as the fluctuations of monosynaptic reflexes. It is concluded that the spontaneous nCDPs were produced by the activation of a population of dorsal horn neurones that shared the same functional pathways and involved the same set of neurones as those responding monosynaptically to stimulation of large cutaneous afferents. The spontaneous activity of these neurones was probably the main cause of the fluctuations of the monosynaptic reflexes observed under anaesthesia and could provide a dynamic linkage between segmental sensory and motor pathways.

Three Hierarchies in Skeletal Muscle Fibre Classification Allotype, Isotype and Phenotype

NASA Technical Reports Server (NTRS)

Hoh, Joseph F. Y.; Hughes, Suzanne; Hugh, Gregory; Pozgaj, Irene

1991-01-01

Immunocytochemical analyses using specific anti-myosin antibodies of mammalian muscle fibers during regeneration, development, and after denervation have revealed two distinct myogenic components determining fiber phenotype. The jaw-closing muscles of the cat contain superfast fibers which express a unique myosin not found in limb muscles. When superfast muscle is transplanted into a limb muscle bed, regenerating myotubes synthesize superfast myosin independent of innervation. Reinnervation by the nerve to a fast muscle leads to the expression of superfast and not fast myosin, while reinnervation by the nerve to a slow muscle leads to the expression of a slow myosin. When limb muscle is transplanted into the jaw muscle bed, only limb myosins are synthesized. Thus jaw and limb muscles belong to distinct allotypes, each with a unique range of phenotype options, the expressions of which may be modulated by the nerve. Primary and secondary myotubes in developing jaw and limb muscles are observed to belong to different categories characterized by different patterns of myosin gene expression. By taking into consideration the pattern of myosins synthesized and the changes in fiber size after denervation, 3 types of primary (fast, slow, and intermediate) fibers can be distinguished in rat fast limb muscles. All primaries synthesize slow myosin soon after their formation, but this is withdrawn in fast and intermediate primaries at different times. After neonatal denervation, slow and intermediate primaries express slow primaries hypertrophy with other fibers atrophy. In the mature rat, the number of slow fibers in the EDL is less than the number of slow primaries. Upon denervation, hypertrophic slow fibers matching the number and topographic distribution of slow primaries appear, suggesting that a subpopulation of the slow primaries acquire the fast phenotype during adult life, but reveal their original identity as slow primaries in response to denervation by hypertrophying

Biomechanical calculation of human TM joint loading with jaw opening.

PubMed

Kuboki, T; Takenami, Y; Maekawa, K; Shinoda, M; Yamashita, A; Clark, G T

2000-11-01

A three-dimensional, static mathematical calculation of the stomatognathic system was done to predict total temporomandibular joint (TMJ) loading at different levels of jaw opening. The model assumed that muscle forces acting on the mandible could be simulated by a combination of contractile components (CCs) and elastic components (ECs) and that static equilibrium existed within the body of the mandible. The model also imposed the constraint that any generated joint reaction force would act on the centre of the condyle. The results of the model demonstrated that under all conditions of opening and for all values of the elastic modulus selected, the forces between the TMJ condyle and the articular eminence were compressive in nature. The compressive force magnitude increased from 2.7 to 27.6 N incrementally as the jaw opened from 10 to 40 mm. Overall data in this study indicated that the TMJ tissues undergo low levels of compression at open positions up to 40 mm. Finally, the condition of trismus (increased jaw closing activation with opening) was simulated, the joint reaction force at 20 mm opening increased from 7.7 to 64.9 N with only a 20% activation of the closers.

Masseter muscular weakness affects temporomandibular synovitis induced by jaw opening in growing rats.

PubMed

Ozaki, Miho; Kaneko, Sawa; Soma, Kunimichi

2008-09-01

To evaluate the influence of impaired masseter function during growth on the development of temporomandibular synovitis. Sixteen 3-week-old male Wistar rats were classified into four groups. The first group served as control; and in the second group, jaw opening was forced for 3 hours when the rats were 9 weeks old. In the third and fourth groups, the masseter muscles were bilaterally resected at 3 weeks of age, and the rats in the fourth group were additionally forced to open their jaw at 9 weeks of age. All rats were sacrificed at 9 weeks. Temporomandibular joint (TMJ) tissue samples were processed for histology, and evaluated for cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) expressions by immunohistochemistry to examine the inflammatory changes in the synovial membrane. The control group showed noninflammatory changes. In the jaw-opening group, vascular dilation and weak COX-2 immunoreactivity were induced by jaw opening in the synovium. In the masseter-resection group, the masseter-resected rats exhibited moderate synovial changes while in the resection with opening group, the masseter-resected rats revealed more significant inflammatory changes including synovial hyperplasia, dilated vasculature, fibrin deposits, and intense immunoreactivity for COX-2 and iNOS, all caused by jaw opening. These results suggest that masseter activity in the growth period is an important factor in the induction of temporomandibular synovitis.

Mechanical design principles of a mitotic spindle.

PubMed

Ward, Jonathan J; Roque, Hélio; Antony, Claude; Nédélec, François

2014-12-18

An organised spindle is crucial to the fidelity of chromosome segregation, but the relationship between spindle structure and function is not well understood in any cell type. The anaphase B spindle in fission yeast has a slender morphology and must elongate against compressive forces. This 'pushing' mode of chromosome transport renders the spindle susceptible to breakage, as observed in cells with a variety of defects. Here we perform electron tomographic analyses of the spindle, which suggest that it organises a limited supply of structural components to increase its compressive strength. Structural integrity is maintained throughout the spindle's fourfold elongation by organising microtubules into a rigid transverse array, preserving correct microtubule number and dynamically rescaling microtubule length.

Cutaneous afferents mediating the cutaneous silent period in the upper limbs: evidences for a role of low-threshold sensory fibres.

PubMed

Serrao, M; Parisi, L; Pierelli, F; Rossi, P

2001-11-01

To evaluate the contribution of the low-threshold afferents to the production of the cutaneous silent period (CSP) in the upper limbs. The CSP was studied in 10 healthy adults and 4 patients with Friedreich's ataxia. The following neurophysiological aspects were studied: (a) relationship between sensory threshold (ST), sensory action potential (SAP) amplitude and CSP parameters; (b) habituation and recovery cycle of the CSP at different stimulus intensities (2xST and 8xST); (c) pattern of responses in distal and proximal muscles at different stimulus intensities (2xST and 8xST). (a) The CSP occurred at low intensities (1xST and 2xST) and increased abruptly between 3.5xST and 4xST (corresponding to the pain threshold). The SAP amplitude was saturated before CSP saturation. In the patients with Friedreich's ataxia, the CSP appeared only at higher stimulus intensities (6xST-8xST). (b) The CSP evoked at 2xST showed a fast habituation and slow recovery cycle whereas the opposite behaviour was found at 8xST. (c) Low-threshold stimuli induced an inhibitory response restricted to the distal muscles. High-intensity stimulation produced an electromyographic suppression, significantly increasing from proximal to distal muscles. Our findings support the notion that low-threshold afferents participate in the production of the CSP in the upper limbs. The different afferents may activate different central neural networks with separate functional significance.

Wavelet Packet Analysis for Angular Data Extraction from Muscle Afferent Cuff Electrode Signals

DTIC Science & Technology

2001-10-25

from rabbits. In order to estimate ankle flexion/extension angles, we recorded ENG signals from the left Tibial and Peroneal nerves, both during FES...afferent ENG. II. METHODOLOGY A. Experimental Setup Acute experiments were conducted with 2 female New Zealand rabbits. The rabbits were pre-anesthetized...fixating the knee and ankle joints in place (see [3] for more details) . For extracting the ENG signals, tripolar cuff electrodes were implanted onto the

Automated frequency analysis of synchronous and diffuse sleep spindles.

PubMed

Huupponen, Eero; Saastamoinen, Antti; Niemi, Jukka; Virkkala, Jussi; Hasan, Joel; Värri, Alpo; Himanen, Sari-Leena

2005-01-01

Sleep spindles have different properties in different localizations in the cortex. First main objective was to develop an amplitude-independent multi-channel spindle detection method. Secondly the method was applied to study the anteroposterior frequency differences of pure synchronous (visible bilaterally, either frontopolarly or centrally) and diffuse (visible bilaterally both frontopolarly and centrally) sleep spindles. A previously presented spindle detector based on the fuzzy reasoning principle and a level detector were combined to form a multi-channel spindle detector. The spindle detector had a 76.17% true positive rate and 0.93% false-positive rate. Pure central spindles were faster and pure frontal spindles were slower than diffuse spindles measured simultaneously from both locations. The study of frequency relations of spindles might give new information about thalamocortical sleep spindle generating mechanisms. Copyright (c) 2005 S. Karger AG, Basel.

Dynamic modulation of corticospinal excitability and short-latency afferent inhibition during onset and maintenance phase of selective finger movement.

PubMed

Cho, Hyun Joo; Panyakaew, Pattamon; Thirugnanasambandam, Nivethida; Wu, Tianxia; Hallett, Mark

2016-06-01

During highly selective finger movement, corticospinal excitability is reduced in surrounding muscles at the onset of movement but this phenomenon has not been demonstrated during maintenance of movement. Sensorimotor integration may play an important role in selective movement. We sought to investigate how corticospinal excitability and short-latency afferent inhibition changes in active and surrounding muscles during onset and maintenance of selective finger movement. Using transcranial magnetic stimulation (TMS) and paired peripheral stimulation, input-output recruitment curve and short-latency afferent inhibition (SAI) were measured in the first dorsal interosseus and abductor digiti minimi muscles during selective index finger flexion. Motor surround inhibition was present only at the onset phase, but not at the maintenance phase of movement. SAI was reduced at onset but not at the maintenance phase of movement in both active and surrounding muscles. Our study showed dynamic changes in corticospinal excitability and sensorimotor modulation for active and surrounding muscles in different movement states. SAI does not appear to contribute to motor surround inhibition at the movement onset phase. Also, there seems to be different inhibitory circuit(s) other than SAI for the movement maintenance phase in order to delineate the motor output selectively when corticospinal excitability is increased in both active and surrounding muscles. This study enhances our knowledge of dynamic changes in corticospinal excitability and sensorimotor interaction in different movement states to understand normal and disordered movements. Published by Elsevier Ireland Ltd.

The Spindle Cell Neoplasms of the Oral Cavity.

PubMed

Shamim, Thorakkal

2015-01-01

Spindle cell neoplasms are defined as neoplasms that consist of spindle-shaped cells in the histopathology. Spindle cell neoplasms can affect the oral cavity. In the oral cavity, the origin of the spindle cell neoplasms may be traced to epithelial, mesenchymal and odontogenic components. This article aims to review the spindle cell neoplasms of the oral cavity with emphasis on histopathology.

The Spindle Cell Neoplasms of the Oral Cavity

PubMed Central

Shamim, Thorakkal

2015-01-01

Spindle cell neoplasms are defined as neoplasms that consist of spindle-shaped cells in the histopathology. Spindle cell neoplasms can affect the oral cavity. In the oral cavity, the origin of the spindle cell neoplasms may be traced to epithelial, mesenchymal and odontogenic components. This article aims to review the spindle cell neoplasms of the oral cavity with emphasis on histopathology. PMID:26351482

Anatomy and adaptations of the chewing muscles in Daubentonia (Lemuriformes).

PubMed

Perry, Jonathan M G; Macneill, Kristen E; Heckler, Amanda L; Rakotoarisoa, Gilbert; Hartstone-Rose, Adam

2014-02-01

The extractive foraging behavior in aye-ayes (Daubentonia madagascariensis) is unique among primates and likely has led to selection for a specialized jaw adductor musculature. Although this musculature has previously been examined in a subadult, until now, no one has reported the fascicle length, weight, and physiological cross-sectional area (PCSA) for these muscles in an adult aye-aye specimen. For the present study, we dissected an adult wild-born aye-aye from the Tsimbazaza Botanical and Zoological Park, Antananarivo, Madagascar. The aye-aye follows the general strepsirrhine pattern in its overall jaw adductor muscle anatomy, but has very large muscles and PCSA relative to body size. Fascicle length is also relatively great, but not nearly as much as in the juvenile aye-aye previously dissected. Perhaps chewing muscle fascicles begin relatively long, but shorten through use and growth as connective tissue sheets expand and allow for pinnation and increased PCSA. Alternately, it may be that aye-ayes develop fascicular adaptation to wide gapes early in ontogeny, only to increase PCSA through later development into adulthood. The functional demands related to their distinctive manner of extractive foraging are likely responsible for the great PCSA in the jaw adductor muscles of the adult aye-aye. It may be that great jaw adductor PCSA in the adult, as compared to the juvenile, is a means of increasing foraging efficiency in the absence of parental assistance. Anat Rec, 297:308-316, 2014. © 2013 Wiley Periodicals, Inc. Copyright © 2013 Wiley Periodicals, Inc.

Mechanical design principles of a mitotic spindle

PubMed Central

Ward, Jonathan J; Roque, Hélio; Antony, Claude; Nédélec, François

2014-01-01

An organised spindle is crucial to the fidelity of chromosome segregation, but the relationship between spindle structure and function is not well understood in any cell type. The anaphase B spindle in fission yeast has a slender morphology and must elongate against compressive forces. This ‘pushing’ mode of chromosome transport renders the spindle susceptible to breakage, as observed in cells with a variety of defects. Here we perform electron tomographic analyses of the spindle, which suggest that it organises a limited supply of structural components to increase its compressive strength. Structural integrity is maintained throughout the spindle's fourfold elongation by organising microtubules into a rigid transverse array, preserving correct microtubule number and dynamically rescaling microtubule length. DOI: http://dx.doi.org/10.7554/eLife.03398.001 PMID:25521247

Jaw elevator silent periods in complete denture wearers and dentate individuals.

PubMed

Celebic, A; Valentic-Peruzovic, M; Alajbeg, I Z; Mehulic, K; Knezovic-Zlataric, D

2008-12-01

Functional meaning and underlying mechanisms of jaw elevator silent period (SP) have still not been completely understood. Since complete denture wearers (CDWs) have no periodontal receptors in their jaws, the aim was to examine SPs in CDWs and to compare it with dentate individuals (DIs). Thirty six DIs (skeletal/occlusal Class I) and 24 eugnath CDWs participated. EMG signals were registered using the EMGA-1 apparatus from the left and the right side anterior temporalis (ATM) and masseter muscles (MM). Ten registrations of an open-close-clench (OCC) cycle were obtained for each individual. DIs had the average latency between 12.5 and 12.9 ms and always one single short inhibitory pause (IP) with complete inhibition of motoneurons (20.1-21.1 ms). On the other hand, in CDWs various types of SPs emerged: single or single prolonged SPs, double SPs, SPs with three IPs, periods of depressed muscle activity following the first, or the second IP, SPs with relative inhibition of motoneurons or even in several registrations the SP was missing. Unless more than one IP emerged, complete duration of inhibitory pauses (CDIP) was measured. CDIP varied from 37.17 to 42.49 ms. Average latencies were from 16.22 to 16.76 ms. Based on the results of this study it is obvious that both, the duration and the latencies were significantly longer in CDWs than in DIs (p<0.05), which can be explained by different mechanisms responsible for the muscle reflex behaviour.

Thalamocortical and intracortical laminar connectivity determines sleep spindle properties.

PubMed

Krishnan, Giri P; Rosen, Burke Q; Chen, Jen-Yung; Muller, Lyle; Sejnowski, Terrence J; Cash, Sydney S; Halgren, Eric; Bazhenov, Maxim

2018-06-27

Sleep spindles are brief oscillatory events during non-rapid eye movement (NREM) sleep. Spindle density and synchronization properties are different in MEG versus EEG recordings in humans and also vary with learning performance, suggesting spindle involvement in memory consolidation. Here, using computational models, we identified network mechanisms that may explain differences in spindle properties across cortical structures. First, we report that differences in spindle occurrence between MEG and EEG data may arise from the contrasting properties of the core and matrix thalamocortical systems. The matrix system, projecting superficially, has wider thalamocortical fanout compared to the core system, which projects to middle layers, and requires the recruitment of a larger population of neurons to initiate a spindle. This property was sufficient to explain lower spindle density and higher spatial synchrony of spindles in the superficial cortical layers, as observed in the EEG signal. In contrast, spindles in the core system occurred more frequently but less synchronously, as observed in the MEG recordings. Furthermore, consistent with human recordings, in the model, spindles occurred independently in the core system but the matrix system spindles commonly co-occurred with core spindles. We also found that the intracortical excitatory connections from layer III/IV to layer V promote spindle propagation from the core to the matrix system, leading to widespread spindle activity. Our study predicts that plasticity of intra- and inter-cortical connectivity can potentially be a mechanism for increased spindle density as has been observed during learning.

Afferent innervation patterns of the saccule in pigeons

NASA Technical Reports Server (NTRS)

Zakir, M.; Huss, D.; Dickman, J. D.

2003-01-01

The innervation patterns of vestibular saccular afferents were quantitatively investigated in pigeons using biotinylated dextran amine as a neural tracer and three-dimensional computer reconstruction. Type I hair cells were found throughout a large portion of the macula, with the highest density observed in the striola. Type II hair cells were located throughout the macula, with the highest density in the extrastriola. Three classes of afferent innervation patterns were observed, including calyx, dimorph, and bouton units, with 137 afferents being anatomically reconstructed and used for quantitative comparisons. Calyx afferents were located primarily in the striola, innervated a number of type I hair cells, and had small innervation areas. Most calyx afferent terminal fields were oriented parallel to the anterior-posterior axis and the morphological polarization reversal line. Dimorph afferents were located throughout the macula, contained fewer type I hair cells in a calyceal terminal than calyx afferents and had medium sized innervation areas. Bouton afferents were restricted to the extrastriola, with multi-branching fibers and large innervation areas. Most of the dimorph and bouton afferents had innervation fields that were oriented dorso-ventrally but were parallel to the neighboring reversal line. The organizational morphology of the saccule was found to be distinctly different from that of the avian utricle or lagena otolith organs and appears to represent a receptor organ undergoing evolutionary adaptation toward sensing linear motion in terrestrial and aerial species.

Self-aligning lathe chuck jaws

DOEpatents

Not Available

1980-08-26

A lathe chuck jaw for a lathe chuck having a radially moving actuator which radially moves the jaw into and out from the workpiece is described. A jaw base part is rigidly connected to the actuator. A jaw shoe part is rotatably attached to the base part. The shoe part has a workpiece-conforming surface which can hold the workpiece. The rotatable attachment of the shoe part allows it to match the general orientation of the workpiece, including a nonlongitudinal orientation due to a workpiece's imperfect shape.

Self-aligning lathe chuck jaws

DOEpatents

Peterson, William R.

1982-01-01

A lathe chuck jaw for a lathe chuck having a radially moving actuator which radially moves the jaw in to and out from the workpiece. A jaw base part is rigidly connected to the actuator. A jaw shoe part is rotatably attached to the base part. The shoe part has a workpiece-comforming surface which can hold the workpiece. The rotatable attachment of the shoe part allows it to match the general orientation of the workpiece, including a nonlongitudinal orientation due to a workpiece's imperfect shape.

Plasticity of gastro-intestinal vagal afferent endings.

PubMed

Kentish, Stephen J; Page, Amanda J

2014-09-01

Vagal afferents are a vital link between the peripheral tissue and central nervous system (CNS). There is an abundance of vagal afferents present within the proximal gastrointestinal tract which are responsible for monitoring and controlling gastrointestinal function. Whilst essential for maintaining homeostasis there is a vast amount of literature emerging which describes remarkable plasticity of vagal afferents in response to endogenous as well as exogenous stimuli. This plasticity for the most part is vital in maintaining healthy processes; however, there are increased reports of vagal plasticity being disrupted in pathological states, such as obesity. Many of the disruptions, observed in obesity, have the potential to reduce vagal afferent satiety signalling which could ultimately perpetuate the obese state. Understanding how plasticity occurs within vagal afferents will open a whole new understanding of gut function as well as identify new treatment options for obesity. Copyright © 2014 Elsevier Inc. All rights reserved.

Biophysical Aspects of Spindle Evolution

NASA Astrophysics Data System (ADS)

Farhadifar, Reza; Baer, Charlie; Needleman, Daniel

2011-03-01

The continual propagation of genetic material from one generation to the next is one of the most basic characteristics of all organisms. In eukaryotes, DNA is segregated into the two daughter cells by a highly dynamic, self-organizing structure called the mitotic spindle. Mitotic spindles can show remarkable variability between tissues and organisms, but there is currently little understanding of the biophysical and evolutionary basis of this diversity. We are studying how spontaneous mutations modify cell division during nematode development. By comparing the mutational variation - the raw material of evolution - with the variation present in nature, we are investigating how the mitotic spindle is shaped over the course of evolution. This combination of quantitative genetics and cellular biophysics gives insight into how the structure and dynamics of the spindle is formed through selection, drift, and biophysical constraints.

Masticatory muscle architecture in a water-rat from Australasia (Murinae, Hydromys) and its implication for the evolution of carnivory in rodents.

PubMed

Fabre, P-H; Herrel, A; Fitriana, Y; Meslin, L; Hautier, L

2017-09-01

Murines are well known for their generalist diet, but several of them display specializations towards a carnivorous diet such as the amphibious Indo-Pacific water-rats. Despite the fact that carnivory evolved repeatedly in this group, few studies have investigated associated changes in jaw muscle anatomy and biomechanics. Here, we describe the jaw muscles and cranial anatomy of a carnivorous water-rat, Hydromys chrysogaster. The architecture of the jaw musculature of six specimens captured both on Obi and Papua were studied and described using dissections. We identified the origin and insertions of the jaw muscles, and quantified muscle mass, fiber length, physiological cross-sectional area, and muscle vectors for each muscle. Using a biomechanical model, we estimated maximum incisor and molar bite force at different gape angles. Finally, we conducted a 2D geometric morphometric analyses to compare jaw shape, mechanical potential, and diversity in lever-arm ratios for a set of 238 specimens, representative of Australo-Papuan carnivorous and omnivorous murids. Our study reveals major changes in the muscle proportions among Hydromys and its omnivorous close relative, Melomys. Hydromys was found to have large superficial masseter and temporalis muscles as well as a reduced deep masseter and zygomatico-mandibularis, highlighting major functional divergence among omnivorous and carnivorous murines. Changes in these muscles are also accompanied by changes in jaw shape and the lines of action of the muscles. A more vertically oriented masseter, reduced masseteric muscles, as well as an elongated jaw with proodont lower incisors are key features indicative of a reduced propalinality in carnivorous Hydromys. Differences in the fiber length of the masseteric muscles were also detected between Hydromys and Melomys, which highlight potential adaptations to a wide gape in Hydromys, allowing it to prey on larger animals. Using a biomechanical model, we inferred a greater bite

Inhibition of Parkinsonian tremor with cutaneous afferent evoked by transcutaneous electrical nerve stimulation.

PubMed

Hao, Man-Zhao; Xu, Shao-Qin; Hu, Zi-Xiang; Xu, Fu-Liang; Niu, Chuan-Xin M; Xiao, Qin; Lan, Ning

2017-07-14

Recent study suggests that tremor signals are transmitted by way of multi-synaptic corticospinal pathway. Neurophysiological studies have also demonstrated that cutaneous afferents exert potent inhibition to descending motor commands by way of spinal interneurons. We hypothesize in this study that cutaneous afferents could also affect the transmission of tremor signals, thus, inhibit tremor in patients with PD. We tested this hypothesis by activating cutaneous afferents in the dorsal hand skin innervated by superficial radial nerve using transcutaneous electrical nerve stimulation (TENS). Eight patients with PD having tremor dominant symptom were recruited to participate in this study using a consistent experimental protocol for tremor inhibition. Resting tremor and electromyogram (EMG) of muscles in the upper extremity of these subjects with PD were recorded, while surface stimulation was applied to the dorsal skin of the hand. Fifteen seconds of data were recorded for 5 s prior to, during and post stimulation. Power spectrum densities (PSDs) of tremor and EMG signals were computed for each data segment. The peak values of PSDs in three data segments were compared to detect evidence of tremor inhibition. At stimulation intensity from 1.5 to 1.75 times of radiating sensation threshold, apparent suppressions of tremor at wrist, forearm and upper arm and in the EMGs were observed immediately at the onset of stimulation. After termination of stimulation, tremor and rhythmic EMG bursts reemerged gradually. Statistical analysis of peak spectral amplitudes showed a significant difference in joint tremors and EMGs during and prior to stimulation in all 8 subjects with PD. The average percentage of suppression was 61.56% in tremor across all joints of all subjects, and 47.97% in EMG of all muscles. The suppression appeared to occur mainly in distal joints and muscles. There was a slight, but inconsistent effect on tremor frequency in the 8 patients with PD tested. Our

[Jaws of amphibians and reptiles].

PubMed

Tanimoto, Masahiro

2005-04-01

Big jaws of amphibians and reptiles are mainly treated in this article. In amphibians enlarged skulls are for the big jaw in contrast with human's skulls for the brain. For example, famous fossils of Homo diluvii testis are ones of salamanders in fact. In reptiles, mosasaur jaws and teeth and their ecology are introduced for instance.

MULTIPOLAR SPINDLE 1 (MPS1), a novel coiled-coil protein of Arabidopsis thaliana, is required for meiotic spindle organization.

PubMed

Jiang, Hua; Wang, Fen-Fei; Wu, Yu-Ting; Zhou, Xi; Huang, Xue-Yong; Zhu, Jun; Gao, Ju-Fang; Dong, Rui-Bin; Cao, Kai-Ming; Yang, Zhong-Nan

2009-09-01

The spindle is essential for chromosome segregation during meiosis, but the molecular mechanism of meiotic spindle organization in higher plants is still not well understood. Here, we report on the identification and characterization of a plant-specific protein, MULTIPOLAR SPINDLE 1 (MPS1), which is involved in spindle organization in meiocytes of Arabidopsis thaliana. The homozygous mps1 mutant exhibits male and female sterility. Light microscopy showed that mps1 mutants produced multiple uneven spores during anther development, most of which aborted in later stages. Cytological analysis showed that chromosome segregation was abnormal in mps1 meiocytes. Immunolocalization showed unequal bipolar or multipolar spindles in mps1 meiocytes, which indicated that aberrant spindles resulted in disordered chromosome segregation. MPS1 encodes a 377-amino-acid protein with putative coiled-coil motifs. In situ hybridization analysis showed that MPS1 is strongly expressed in meiocytes.

Three-dimensional finite element modelling of muscle forces during mastication.

PubMed

Röhrle, Oliver; Pullan, Andrew J

2007-01-01

This paper presents a three-dimensional finite element model of human mastication. Specifically, an anatomically realistic model of the masseter muscles and associated bones is used to investigate the dynamics of chewing. A motion capture system is used to track the jaw motion of a subject chewing standard foods. The three-dimensional nonlinear deformation of the masseter muscles are calculated via the finite element method, using the jaw motion data as boundary conditions. Motion-driven muscle activation patterns and a transversely isotropic material law, defined in a muscle-fibre coordinate system, are used in the calculations. Time-force relationships are presented and analysed with respect to different tasks during mastication, e.g. opening, closing, and biting, and are also compared to a more traditional one-dimensional model. The results strongly suggest that, due to the complex arrangement of muscle force directions, modelling skeletal muscles as conventional one-dimensional lines of action might introduce a significant source of error.

Piezo Is Essential for Amiloride-Sensitive Stretch-Activated Mechanotransduction in Larval Drosophila Dorsal Bipolar Dendritic Sensory Neurons

PubMed Central

Suslak, Thomas J.; Watson, Sonia; Thompson, Karen J.; Shenton, Fiona C.; Bewick, Guy S.; Armstrong, J. Douglas; Jarman, Andrew P.

2015-01-01

Stretch-activated afferent neurons, such as those of mammalian muscle spindles, are essential for proprioception and motor co-ordination, but the underlying mechanisms of mechanotransduction are poorly understood. The dorsal bipolar dendritic (dbd) sensory neurons are putative stretch receptors in the Drosophila larval body wall. We have developed an in vivo protocol to obtain receptor potential recordings from intact dbd neurons in response to stretch. Receptor potential changes in dbd neurons in response to stretch showed a complex, dynamic profile with similar characteristics to those previously observed for mammalian muscle spindles. These profiles were reproduced by a general in silico model of stretch-activated neurons. This in silico model predicts an essential role for a mechanosensory cation channel (MSC) in all aspects of receptor potential generation. Using pharmacological and genetic techniques, we identified the mechanosensory channel, DmPiezo, in this functional role in dbd neurons, with TRPA1 playing a subsidiary role. We also show that rat muscle spindles exhibit a ruthenium red-sensitive current, but found no expression evidence to suggest that this corresponds to Piezo activity. In summary, we show that the dbd neuron is a stretch receptor and demonstrate that this neuron is a tractable model for investigating mechanisms of mechanotransduction. PMID:26186008

Piezo Is Essential for Amiloride-Sensitive Stretch-Activated Mechanotransduction in Larval Drosophila Dorsal Bipolar Dendritic Sensory Neurons.

PubMed

Suslak, Thomas J; Watson, Sonia; Thompson, Karen J; Shenton, Fiona C; Bewick, Guy S; Armstrong, J Douglas; Jarman, Andrew P

2015-01-01

Stretch-activated afferent neurons, such as those of mammalian muscle spindles, are essential for proprioception and motor co-ordination, but the underlying mechanisms of mechanotransduction are poorly understood. The dorsal bipolar dendritic (dbd) sensory neurons are putative stretch receptors in the Drosophila larval body wall. We have developed an in vivo protocol to obtain receptor potential recordings from intact dbd neurons in response to stretch. Receptor potential changes in dbd neurons in response to stretch showed a complex, dynamic profile with similar characteristics to those previously observed for mammalian muscle spindles. These profiles were reproduced by a general in silico model of stretch-activated neurons. This in silico model predicts an essential role for a mechanosensory cation channel (MSC) in all aspects of receptor potential generation. Using pharmacological and genetic techniques, we identified the mechanosensory channel, DmPiezo, in this functional role in dbd neurons, with TRPA1 playing a subsidiary role. We also show that rat muscle spindles exhibit a ruthenium red-sensitive current, but found no expression evidence to suggest that this corresponds to Piezo activity. In summary, we show that the dbd neuron is a stretch receptor and demonstrate that this neuron is a tractable model for investigating mechanisms of mechanotransduction.

Marcus Gunn jaw-winking synkinesis: clinical features and management.

PubMed

Demirci, Hakan; Frueh, Bartley R; Nelson, Christine C

2010-07-01

To evaluate the clinical features including eyelid excursion and management of Marcus Gunn jaw-winking synkinesis (MGJWS). Observational case series. Forty-eight consecutive patients with MGJWS. Clinical features and management of 48 patients with MGJWS were reviewed retrospectively. Upper eyelid excursion was measured and graded. Complications of surgical intervention were evaluated. Resolution of MGJWS and symmetry of upper eyelids in primary position. Excursion of the ptotic eyelid with jaw movement in MGJWS was graded as mild (<2 mm) in 16% of patients, moderate (2-4 mm) in 76% of patients, and severe (> or = 5 mm) in 8% of patients. Thirty patients with moderate or severe MGJWS underwent disabling of the involved levator muscle and bilateral or unilateral frontalis suspension and had more than 6 months of follow-up. After a mean follow-up of 62 months, MGJWS resolved in 29 (97%) patients and improved from 6 mm to 2 mm in 1 (3%) patient. Relative upper eyelid height was within 1 mm in 87% of patients in primary position and within 1 mm in 80% of patients in downgaze. Twenty-six patients had bilateral frontalis suspension with disabling of unilateral levator muscle on the involved side. Relative upper eyelid height was within 1 mm in 88% of patients in the primary position and within 1 mm in 88% of patients in downgaze. Four non-amblyopic patients had unilateral frontalis suspension with levator muscle disabling. Relative upper eyelid height was symmetrical in 75% of the patients in primary position and in 25% of patients in downgaze. Complications included eyelash ptosis in 10% of the patients, loss of eyelid crease in 10%, and entropion in 3%. Most of the patients with MGJWS exhibited moderate eyelid excursion. Disabling of the involved levator muscle and bilateral frontalis suspension and, in selected cases, disabling of the involved levator muscle and unilateral frontalis suspension were effective in the treatment of MGJWS. Eyelash ptosis and loss of eyelid

Proteinase-Activated Receptor-2 Sensitivity of Amplified TRPA1 Activity in Skeletal Muscle Afferent Nerves and Exercise Pressor Reflex in Rats with Femoral Artery Occlusion

PubMed Central

Xing, Jihong; Li, Jianhua

2017-01-01

Background/Aims Limb ischemia occurs in peripheral artery disease (PAD). Sympathetic nerve activity (SNA) that regulates blood flow directed to the ischemic limb is exaggerated during exercise in this disease, and transient receptor potential channel A1 (TRPA1) in thin-fiber muscle afferents contributes to the amplified sympathetic response. The purpose of the present study was to determine the role of proteinase-activated receptor-2 (PAR2) in regulating abnormal TRPA1 function and the TRPA1-mediated sympathetic component of the exercise pressor reflex. Methods A rat model of femoral artery ligation was employed to study PAD. Dorsal root ganglion (DRG) tissues were obtained to examine the protein levels of PAR2 using western blot analysis. Current responses induced by activation of TRPA1 in skeletal muscle DRG neurons were characterized using whole-cell patch clamp methods. The blood pressure response to static exercise (i.e., muscle contraction) and stimulation of TRPA1 was also examined after a blockade of PAR2. Results The expression of PAR2 was amplified in DRG neurons of the occluded limb, and PAR2 activation with SL-NH2 (a PAR2 agonist) increased the amplitude of TRPA1 currents to a greater degree in DRG neurons of the occluded limb. Moreover, FSLLRY-NH2 (a PAR antagonist) injected into the arterial blood supply of the hindlimb muscles significantly attenuated the pressor response to muscle contraction and TRPA1 stimulation in rats with occluded limbs. Conclusions The PAR2 signal in muscle sensory nerves contributes to the amplified exercise pressor reflex via TRPA1 mechanisms in rats with femoral artery ligation. These findings provide a pathophysiological basis for autonomic responses during exercise activity in PAD, which may potentially aid in the development of therapeutic approaches for improvement of blood flow in this disease. PMID:29131007

Effect of afferent feedback and central motor commands on soleus H-reflex suppression during arm cycling.

PubMed

Hundza, S R; de Ruiter, Geoff C; Klimstra, M; Zehr, E Paul

2012-12-01

Suppression of soleus H-reflex amplitude in stationary legs is seen during rhythmic arm cycling. We examined the influence of various arm-cycling parameters on this interlimb reflex modulation to determine the origin of the effect. We previously showed the suppression to be graded with the frequency of arm cycling but not largely influenced by changes in peripheral input associated with crank length. Here, we more explicitly explored the contribution of afferent feedback related to arm movement on the soleus H-reflex suppression. We explored the influence of load and rate of muscle stretch by manipulating crank-load and arm-muscle vibration during arm cycling. Furthermore, internally driven ("Active") and externally driven ("Passive") arm cycling was compared. Soleus H-reflexes were evoked with tibial nerve stimulation during stationary control and rhythmic arm-cycling conditions, including: 1) six different loads; 2) with and without vibration to arm muscles; and 3) Active and Passive conditions. No significant differences were seen in the level of suppression between the different crank loads or between conditions with and without arm-muscle vibration. Furthermore, in contrast to the clear effect seen during active cycling, passive arm cycling did not significantly suppress the soleus H-reflex amplitude. Current results, in conjunction with previous findings, suggest that the afferent feedback examined in these studies is not the primary source responsible for soleus H-reflex suppression. Instead, it appears that central motor commands (supraspinal or spinal in origin) associated with frequency of arm cycling are relatively more dominant sources.

Broken or dislocated jaw

MedlinePlus

... broken or dislocated jaw requires prompt medical attention. Emergency symptoms include difficulty breathing or heavy bleeding. ... safety equipment, such as a helmet when playing football, or using ... can prevent or minimize some injuries to the face or jaw.

Afferent Connectivity of the Zebrafish Habenulae

PubMed Central

Turner, Katherine J.; Hawkins, Thomas A.; Yáñez, Julián; Anadón, Ramón; Wilson, Stephen W.; Folgueira, Mónica

2016-01-01

The habenulae are bilateral nuclei located in the dorsal diencephalon that are conserved across vertebrates. Here we describe the main afferents to the habenulae in larval and adult zebrafish. We observe afferents from the subpallium, nucleus rostrolateralis, posterior tuberculum, posterior hypothalamic lobe, median raphe; we also see asymmetric afferents from olfactory bulb to the right habenula, and from the parapineal to the left habenula. In addition, we find afferents from a ventrolateral telencephalic nucleus that neurochemical and hodological data identify as the ventral entopeduncular nucleus (vENT), confirming and extending observations of Amo et al. (2014). Fate map and marker studies suggest that vENT originates from the diencephalic prethalamic eminence and extends into the lateral telencephalon from 48 to 120 hour post-fertilization (hpf). No afferents to the habenula were observed from the dorsal entopeduncular nucleus (dENT). Consequently, we confirm that the vENT (and not the dENT) should be considered as the entopeduncular nucleus “proper” in zebrafish. Furthermore, comparison with data in other vertebrates suggests that the vENT is a conserved basal ganglia nucleus, being homologous to the entopeduncular nucleus of mammals (internal segment of the globus pallidus of primates) by both embryonic origin and projections, as previously suggested by Amo et al. (2014). PMID:27199671

Measuring mitotic spindle dynamics in budding yeast

NASA Astrophysics Data System (ADS)

Plumb, Kemp

In order to carry out its life cycle and produce viable progeny through cell division, a cell must successfully coordinate and execute a number of complex processes with high fidelity, in an environment dominated by thermal noise. One important example of such a process is the assembly and positioning of the mitotic spindle prior to chromosome segregation. The mitotic spindle is a modular structure composed of two spindle pole bodies, separated in space and spanned by filamentous proteins called microtubules, along which the genetic material of the cell is held. The spindle is responsible for alignment and subsequent segregation of chromosomes into two equal parts; proper spindle positioning and timing ensure that genetic material is appropriately divided amongst mother and daughter cells. In this thesis, I describe fluorescence confocal microscopy and automated image analysis algorithms, which I have used to observe and analyze the real space dynamics of the mitotic spindle in budding yeast. The software can locate structures in three spatial dimensions and track their movement in time. By selecting fluorescent proteins which specifically label the spindle poles and cell periphery, mitotic spindle dynamics have been measured in a coordinate system relevant to the cell division. I describe how I have characterised the accuracy and precision of the algorithms by simulating fluorescence data for both spindle poles and the budding yeast cell surface. In this thesis I also describe the construction of a microfluidic apparatus that allows for the measurement of long time-scale dynamics of individual cells and the development of a cell population. The tools developed in this thesis work will facilitate in-depth quantitative analysis of the non-equilibrium processes in living cells.

Dual-afferent sensory input training for voluntary movement after stroke: A pilot randomized controlled study.

PubMed

Bae, Seahyun; Kim, Kyung-Yoon

2017-01-01

Stimulation through afferent sensory input is necessary to improve voluntary functional movement in stroke patients. Dual-afferent sensory input, which combines electromyography-triggered functional electric stimulation (ETFES) and action observation, was investigated to determine its effects on voluntary movements in stroke patients. This study was conducted on 18 patients with left hemiplegia diagnosed between 6 and 24 months prior. The 9 subjects in the dual-afferent sensory input (DASI) group underwent ETFES with action observation training for 4 weeks (20 min/d, 5 d/wk), while the 9 control group subjects underwent functional electric stimulation (FES) for the same duration. The outcome measures were the movement-related cortical potential (MRCP), H-reflex, electromyography (EMG), and balance. The control and DASI groups showed significant increases in MRCP, muscle activity, and balance, while H-reflex was significantly decreased. MRCP and balance showed significant differences between DASI and control groups. DASI stimulates voluntary movement in patients, causes rapid activation of the cerebral cortex, and reduces excessive excitation of spinal motor neurons. Therefore, DASI, which stimulates voluntary movement, has a greater effect on brain activation in stroke patients.

Afferent innervation of the utricular macula in pigeons

NASA Technical Reports Server (NTRS)

Si, Xiaohong; Zakir, Mridha Md; Dickman, J. David

2003-01-01

Biotinylated dextran amine (BDA) was used to retrogradely label afferents innervating the utricular macula in adult pigeons. The pigeon utriclar macula consists of a large rectangular-shaped neuroepithelium with a dorsally curved anterior edge and an extended medioposterior tail. The macula could be demarcated into several regions based on cytoarchitectural differences. The striola occupied 30% of the macula and contained a large density of type I hair cells with fewer type II hair cells. Medial and lateral extrastriola zones were located outside the striola and contained only type II hair cells. A six- to eight-cell-wide band of type II hair cells existed near the center of the striola. The reversal line marked by the morphological polarization of hair cells coursed throughout the epithelium, near the peripheral margin, and through the center of the type II band. Calyx afferents innervated type I hair cells with calyceal terminals that contained between 2 and 15 receptor cells. Calyx afferents were located only in the striola region, exclusive of the type II band, had small total fiber innervation areas and low innervation densities. Dimorph afferents innervated both type I and type II hair cells with calyceal and bouton terminals and were primarily located in the striola region. Dimorph afferents had smaller calyceal terminals with few type I hair cells, extended fiber branches with bouton terminals and larger innervation areas. Bouton afferents innervated only type II hair cells in the extrastriola and type II band regions. Bouton afferents innervating the type II band had smaller terminal fields with fewer bouton terminals and smaller innervation areas than fibers located in the extrastriolar zones. Bouton afferents had the most bouton terminals on the longest fibers, the largest innervation areas with the highest innervation densities of all afferents. Among all afferents, smaller terminal innervation fields were observed in the striola and large fields were

A defect-driven diagnostic method for machine tool spindles

PubMed Central

Vogl, Gregory W.; Donmez, M. Alkan

2016-01-01

Simple vibration-based metrics are, in many cases, insufficient to diagnose machine tool spindle condition. These metrics couple defect-based motion with spindle dynamics; diagnostics should be defect-driven. A new method and spindle condition estimation device (SCED) were developed to acquire data and to separate system dynamics from defect geometry. Based on this method, a spindle condition metric relying only on defect geometry is proposed. Application of the SCED on various milling and turning spindles shows that the new approach is robust for diagnosing the machine tool spindle condition. PMID:28065985

[Acute pancreatitis and afferent loop syndrome. Case report].

PubMed

Barajas-Fregoso, Elpidio Manuel; Romero-Hernández, Teodoro; Macías-Amezcua, Michel Dassaejv

2013-01-01

The afferent syndrome loop is a mechanic obstruction of the afferent limb before a Billroth II or Roux-Y reconstruction, secondary in most of case to distal or subtotal gastrectomy. Clinical case: Male 76 years old, with antecedent of cholecystectomy, gastric adenocarcinoma six years ago, with subtotal gastrectomy and Roux-Y reconstruction. Beginning a several abdominal pain, nausea and vomiting, abdominal distension, without peritoneal irritation sings. Amylase 1246 U/L, lipase 3381 U/L. Computed Tomography with thickness wall and dilatation of afferent loop, pancreas with diffuse enlargement diagnostic of acute pancreatitis secondary an afferent loop syndrome. The afferent loop syndrome is presented in 0.3%-1% in all cases with Billroth II reconstruction, with a mortality of up to 57%, the obstruction lead accumulation of bile, pancreatic and intestinal secretions, increasing the pressure and resulting in afferent limb, bile conduct and Wirsung conduct dilatation, triggering an inflammatory response that culminates in pancreatic inflammation. The severity of the presentation is related to the degree and duration of the blockage.

Resting Afferent Renal Nerve Discharge and Renal Inflammation: Elucidating the Role of Afferent and Efferent Renal Nerves in Deoxycorticosterone Acetate Salt Hypertension.

PubMed

Banek, Christopher T; Knuepfer, Mark M; Foss, Jason D; Fiege, Jessica K; Asirvatham-Jeyaraj, Ninitha; Van Helden, Dusty; Shimizu, Yoji; Osborn, John W

2016-12-01

Renal sympathetic denervation (RDNx) has emerged as a novel therapy for hypertension; however, the therapeutic mechanisms remain unclear. Efferent renal sympathetic nerve activity has recently been implicated in trafficking renal inflammatory immune cells and inflammatory chemokine and cytokine release. Several of these inflammatory mediators are known to activate or sensitize afferent nerves. This study aimed to elucidate the roles of efferent and afferent renal nerves in renal inflammation and hypertension in the deoxycorticosterone acetate (DOCA) salt rat model. Uninephrectomized male Sprague-Dawley rats (275-300 g) underwent afferent-selective RDNx (n=10), total RDNx (n=10), or Sham (n=10) and were instrumented for the measurement of mean arterial pressure and heart rate by radiotelemetry. Rats received 100-mg DOCA (SC) and 0.9% saline for 21 days. Resting afferent renal nerve activity in DOCA and vehicle animals was measured after the treatment protocol. Renal tissue inflammation was assessed by renal cytokine content and T-cell infiltration and activation. Resting afferent renal nerve activity, expressed as a percent of peak afferent nerve activity, was substantially increased in DOCA than in vehicle (35.8±4.4 versus 15.3±2.8 %Amax). The DOCA-Sham hypertension (132±12 mm Hg) was attenuated by ≈50% in both total RDNx (111±8 mm Hg) and afferent-selective RDNx (117±5 mm Hg) groups. Renal inflammation induced by DOCA salt was attenuated by total RDNx and unaffected by afferent-selective RDNx. These data suggest that afferent renal nerve activity may mediate the hypertensive response to DOCA salt, but inflammation may be mediated primarily by efferent renal sympathetic nerve activity. Also, resting afferent renal nerve activity is elevated in DOCA salt rats, which may highlight a crucial neural mechanism in the development and maintenance of hypertension. © 2016 American Heart Association, Inc.

Electrophysiological characterization of human rectal afferents

PubMed Central

Ng, Kheng-Seong; Brookes, Simon J.; Montes-Adrian, Noemi A.; Mahns, David A.

2016-01-01

It is presumed that extrinsic afferent nerves link the rectum to the central nervous system. However, the anatomical/functional existence of such nerves has never previously been demonstrated in humans. Therefore, we aimed to identify and make electrophysiological recordings in vitro from extrinsic afferents, comparing human rectum to colon. Sections of normal rectum and colon were procured from anterior resection and right hemicolectomy specimens, respectively. Sections were pinned and extrinsic nerves dissected. Extracellular visceral afferent nerve activity was recorded. Neuronal responses to chemical [capsaicin and “inflammatory soup” (IS)] and mechanical (Von Frey probing) stimuli were recorded and quantified as peak firing rate (range) in 1-s intervals. Twenty-eight separate nerve trunks from eight rectums were studied. Of these, spontaneous multiunit afferent activity was recorded in 24 nerves. Peak firing rates increased significantly following capsaicin [median 6 (range 3–25) spikes/s vs. 2 (1–4), P < 0.001] and IS [median 5 (range 2–18) spikes/s vs. 2 (1–4), P < 0.001]. Mechanosensitive “hot spots” were identified in 16 nerves [median threshold 2.0 g (range 1.4–6.0 g)]. In eight of these, the threshold decreased after IS [1.0 g (0.4–1.4 g)]. By comparison, spontaneous activity was recorded in only 3/30 nerves studied from 10 colons, and only one hot spot (threshold 60 g) was identified. This study confirms the anatomical/functional existence of extrinsic rectal afferent nerves and characterizes their chemo- and mechanosensitivity for the first time in humans. They have different electrophysiological properties to colonic afferents and warrant further investigation in disease states. PMID:27789454

Intracortical circuits, sensorimotor integration and plasticity in human motor cortical projections to muscles of the lower face

PubMed Central

Pilurzi, G; Hasan, A; Saifee, T A; Tolu, E; Rothwell, J C; Deriu, F

2013-01-01

Previous studies of the cortical control of human facial muscles documented the distribution of corticobulbar projections and the presence of intracortical inhibitory and facilitatory mechanisms. Yet surprisingly, given the importance and precision in control of facial expression, there have been no studies of the afferent modulation of corticobulbar excitability or of the plasticity of synaptic connections in the facial primary motor cortex (face M1). In 25 healthy volunteers, we used standard single- and paired-pulse transcranial magnetic stimulation (TMS) methods to probe motor-evoked potentials (MEPs), short-intracortical inhibition, intracortical facilitation, short-afferent and long-afferent inhibition and paired associative stimulation in relaxed and active depressor anguli oris muscles. Single-pulse TMS evoked bilateral MEPs at rest and during activity that were larger in contralateral muscles, confirming that corticobulbar projection to lower facial muscles is bilateral and asymmetric, with contralateral predominance. Both short-intracortical inhibition and intracortical facilitation were present bilaterally in resting and active conditions. Electrical stimulation of the facial nerve paired with a TMS pulse 5–200 ms later showed no short-afferent inhibition, but long-afferent inhibition was present. Paired associative stimulation tested with an electrical stimulation–TMS interval of 20 ms significantly facilitated MEPs for up to 30 min. The long-term potentiation, evoked for the first time in face M1, demonstrates that excitability of the facial motor cortex is prone to plastic changes after paired associative stimulation. Evaluation of intracortical circuits in both relaxed and active lower facial muscles as well as of plasticity in the facial motor cortex may provide further physiological insight into pathologies affecting the facial motor system. PMID:23297305

Measurement of jaw motion: the proposal of a simple and accurate method.

PubMed

Pinheiro, A P; Pereira, A A; Andrade, A O; Bellomo, D

2011-01-01

The analysis of jaw movements has long been used as a measure for clinical diagnosis and assessment. A number of strategies are available for monitoring the trajectory; however most of these strategies make use of expensive tools, which are often not available to many clinics in the world. In this context, this research proposes the development of a new tool capable of quantifying the movements of opening/closing, protrusion and laterotrusion of the mandible. These movements are important for the clinical evaluation of both the temporomandibular function and muscles involved in mastication. The proposed system, unlike current commercial systems, employs a low-cost video camera and a computer program, which is used for reconstructing the trajectory of a reflective marker that is fixed on the jaw. In order to illustrate the application of the devised tool a clinical trial was carried out, investigating jaw movements of 10 subjects. The results obtained in this study were compatible with those found in the literature with the advantage of using a low-cost, simple, non-invasive and flexible solution customized for the practical needs of clinics. The average error of the system was less than 1.0%.

Targeting Alp7/TACC to the spindle pole body is essential for mitotic spindle assembly in fission yeast

PubMed Central

Tang, Ngang Heok; Okada, Naoyuki; Fong, Chii Shyang; Arai, Kunio; Sato, Masamitsu; Toda, Takashi

2014-01-01

The conserved TACC protein family localises to the centrosome (the spindle pole body, SPB in fungi) and mitotic spindles, thereby playing a crucial role in bipolar spindle assembly. However, it remains elusive how TACC proteins are recruited to the centrosome/SPB. Here, using fission yeast Alp7/TACC, we have determined clustered five amino acid residues within the TACC domain required for SPB localisation. Critically, these sequences are essential for the functions of Alp7, including proper spindle formation and mitotic progression. Moreover, we have identified pericentrin-like Pcp1 as a loading factor to the mitotic SPB, although Pcp1 is not a sole platform. PMID:24937146

The oculomotor system of decapod cephalopods: eye muscles, eye muscle nerves, and the oculomotor neurons in the central nervous system.

PubMed

Budelmann, B U; Young, J Z

1993-04-29

Fourteen extraocular eye muscles are described in the decapods Loligo and Sepioteuthis, and thirteen in Sepia; they are supplied by four eye muscle nerves. The main action of most of the muscles is a linear movement of the eyeball, only three muscles produce strong rotations. The arrangement, innervation and action of the decapod eye muscles are compared with those of the seven eye muscles and seven eye muscle nerves in Octopus. The extra muscles in decapods are attached to the anterior and superior faces of the eyes. At least, the anterior muscles, and presumably also the superior muscles, are concerned with convergent eye movements for binocular vision during fixation and capture of prey by the tentacles. The remaining muscles are rather similar in the two cephalopod groups. In decapods, the anterior muscles include conjunctive muscles; these cross the midline and each presumably moves both eyes at the same time during fixation. In the squids Loligo and Sepioteuthis there is an additional superior conjunctive muscle of perhaps similar function. Some of the anterior muscles are associated with a narrow moveable plate, the trochlear cartilage; it is attached to the eyeball by trochlear membranes. Centripetal cobalt fillings showed that all four eye muscle nerves have fibres that originate from somata in the ipsilateral anterior lateral pedal lobe, which is the oculomotor centre. The somata of the individual nerves show different but overlapping distributions. Bundles of small presumably afferent fibres were seen in two of the four nerves. They do not enter the anterior lateral pedal lobe but run to the ventral magnocellular lobe; some afferent fibres enter the brachio-palliovisceral connective and run perhaps as far as the palliovisceral lobe.

Presence and Absence of Muscle Contraction Elicited by Peripheral Nerve Electrical Stimulation Differentially Modulate Primary Motor Cortex Excitability.

PubMed

Sasaki, Ryoki; Kotan, Shinichi; Nakagawa, Masaki; Miyaguchi, Shota; Kojima, Sho; Saito, Kei; Inukai, Yasuto; Onishi, Hideaki

2017-01-01

Modulation of cortical excitability by sensory inputs is a critical component of sensorimotor integration. Sensory afferents, including muscle and joint afferents, to somatosensory cortex (S1) modulate primary motor cortex (M1) excitability, but the effects of muscle and joint afferents specifically activated by muscle contraction are unknown. We compared motor evoked potentials (MEPs) following median nerve stimulation (MNS) above and below the contraction threshold based on the persistence of M-waves. Peripheral nerve electrical stimulation (PES) conditions, including right MNS at the wrist at 110% motor threshold (MT; 110% MNS condition), right MNS at the index finger (sensory digit nerve stimulation [DNS]) with stimulus intensity approximately 110% MNS (DNS condition), and right MNS at the wrist at 90% MT (90% MNS condition) were applied. PES was administered in a 4 s ON and 6 s OFF cycle for 20 min at 30 Hz. In Experiment 1 ( n = 15), MEPs were recorded from the right abductor pollicis brevis (APB) before (baseline) and after PES. In Experiment 2 ( n = 15), M- and F-waves were recorded from the right APB. Stimulation at 110% MNS at the wrist evoking muscle contraction increased MEP amplitudes after PES compared with those at baseline, whereas DNS at the index finger and 90% MNS at the wrist not evoking muscle contraction decreased MEP amplitudes after PES. M- and F-waves, which reflect spinal cord or muscular and neuromuscular junctions, did not change following PES. These results suggest that muscle contraction and concomitant muscle/joint afferent inputs specifically enhance M1 excitability.

Presence and Absence of Muscle Contraction Elicited by Peripheral Nerve Electrical Stimulation Differentially Modulate Primary Motor Cortex Excitability

PubMed Central

Sasaki, Ryoki; Kotan, Shinichi; Nakagawa, Masaki; Miyaguchi, Shota; Kojima, Sho; Saito, Kei; Inukai, Yasuto; Onishi, Hideaki

2017-01-01

Modulation of cortical excitability by sensory inputs is a critical component of sensorimotor integration. Sensory afferents, including muscle and joint afferents, to somatosensory cortex (S1) modulate primary motor cortex (M1) excitability, but the effects of muscle and joint afferents specifically activated by muscle contraction are unknown. We compared motor evoked potentials (MEPs) following median nerve stimulation (MNS) above and below the contraction threshold based on the persistence of M-waves. Peripheral nerve electrical stimulation (PES) conditions, including right MNS at the wrist at 110% motor threshold (MT; 110% MNS condition), right MNS at the index finger (sensory digit nerve stimulation [DNS]) with stimulus intensity approximately 110% MNS (DNS condition), and right MNS at the wrist at 90% MT (90% MNS condition) were applied. PES was administered in a 4 s ON and 6 s OFF cycle for 20 min at 30 Hz. In Experiment 1 (n = 15), MEPs were recorded from the right abductor pollicis brevis (APB) before (baseline) and after PES. In Experiment 2 (n = 15), M- and F-waves were recorded from the right APB. Stimulation at 110% MNS at the wrist evoking muscle contraction increased MEP amplitudes after PES compared with those at baseline, whereas DNS at the index finger and 90% MNS at the wrist not evoking muscle contraction decreased MEP amplitudes after PES. M- and F-waves, which reflect spinal cord or muscular and neuromuscular junctions, did not change following PES. These results suggest that muscle contraction and concomitant muscle/joint afferent inputs specifically enhance M1 excitability. PMID:28392766

Interaction between vestibulosympathetic and skeletal muscle reflexes on sympathetic activity in humans

NASA Technical Reports Server (NTRS)

Ray, C. A.

2001-01-01

Evidence from animals indicates that skeletal muscle afferents activate the vestibular nuclei and that both vestibular and skeletal muscle afferents have inputs to the ventrolateral medulla. The purpose of the present study was to investigate the interaction between the vestibulosympathetic and skeletal muscle reflexes on muscle sympathetic nerve activity (MSNA) and arterial pressure in humans. MSNA, arterial pressure, and heart rate were measured in 17 healthy subjects in the prone position during three experimental trials. The three trials were 2 min of 1) head-down rotation (HDR) to engage the vestibulosympathetic reflex, 2) isometric handgrip (IHG) at 30% maximal voluntary contraction to activate skeletal muscle afferents, and 3) HDR and IHG performed simultaneously. The order of the three trials was randomized. HDR and IHG performed alone increased total MSNA by 46 +/- 16 and 77 +/- 24 units, respectively (P < 0.01). During the HDR plus IHG trial, MSNA increased 142 +/- 38 units (P < 0.01). This increase was not significantly different from the sum of the individual trials (130 +/- 41 units). This finding was also observed with mean arterial pressure (sum = 21 +/- 2 mmHg and HDR + IHG = 22 +/- 2 mmHg). These findings suggest that there is an additive interaction for MSNA and arterial pressure when the vestibulosympathetic and skeletal muscle reflexes are engaged simultaneously in humans. Therefore, no central modulation exists between these two reflexes with regard to MSNA output in humans.

Measuring and modeling polymer concentration profiles near spindle boundaries argues that spindle microtubules regulate their own nucleation

NASA Astrophysics Data System (ADS)

Kaye, Bryan; Stiehl, Olivia; Foster, Peter J.; Shelley, Michael J.; Needleman, Daniel J.; Fürthauer, Sebastian

2018-05-01

Spindles are self-organized microtubule-based structures that segregate chromosomes during cell division. The mass of the spindle is controlled by the balance between microtubule turnover and nucleation. The mechanisms that control the spatial regulation of microtubule nucleation remain poorly understood. While previous work found that microtubule nucleators bind to pre-existing microtubules in the spindle, it is still unclear whether this binding regulates the activity of those nucleators. Here we use a combination of experiments and mathematical modeling to investigate this issue. We measured the concentration of microtubules and soluble tubulin in and around the spindle. We found a very sharp decay in the concentration of microtubules at the spindle interface. This is inconsistent with a model in which the activity of nucleators is independent of their association with microtubules but consistent with a model in which microtubule nucleators are only active when bound to pre-existing microtubules. This argues that the activity of microtubule nucleators is greatly enhanced when bound to pre-existing microtubules. Thus, microtubule nucleators are both localized and activated by the microtubules they generate.

Inscuteable Regulates the Pins-Mud Spindle Orientation Pathway

PubMed Central

Mauser, Jonathon F.; Prehoda, Kenneth E.

2012-01-01

During asymmetric cell division, alignment of the mitotic spindle with the cell polarity axis ensures that the cleavage furrow separates fate determinants into distinct daughter cells. The protein Inscuteable (Insc) is thought to link cell polarity and spindle positioning in diverse systems by binding the polarity protein Bazooka (Baz; aka Par-3) and the spindle orienting protein Partner of Inscuteable (Pins; mPins or LGN in mammals). Here we investigate the mechanism of spindle orientation by the Insc-Pins complex. Previously, we defined two Pins spindle orientation pathways: a complex with Mushroom body defect (Mud; NuMA in mammals) is required for full activity, whereas binding to Discs large (Dlg) is sufficient for partial activity. In the current study, we have examined the role of Inscuteable in mediating downstream Pins-mediated spindle orientation pathways. We find that the Insc-Pins complex requires Gαi for partial activity and that the complex specifically recruits Dlg but not Mud. In vitro competition experiments revealed that Insc and Mud compete for binding to the Pins TPR motifs, while Dlg can form a ternary complex with Insc-Pins. Our results suggest that Insc does not passively couple polarity and spindle orientation but preferentially inhibits the Mud pathway, while allowing the Dlg pathway to remain active. Insc-regulated complex assembly may ensure that the spindle is attached to the cortex (via Dlg) before activation of spindle pulling forces by Dynein/Dynactin (via Mud). PMID:22253744

Self-Organization and Forces in the Mitotic Spindle.

PubMed

Pavin, Nenad; Tolić, Iva M

2016-07-05

At the onset of division, the cell forms a spindle, a precise self-constructed micromachine composed of microtubules and the associated proteins, which divides the chromosomes between the two nascent daughter cells. The spindle arises from self-organization of microtubules and chromosomes, whose different types of motion help them explore the space and eventually approach and interact with each other. Once the interactions between the chromosomes and the microtubules have been established, the chromosomes are moved to the equatorial plane of the spindle and ultimately toward the opposite spindle poles. These transport processes rely on directed forces that are precisely regulated in space and time. In this review, we discuss how microtubule dynamics and their rotational movement drive spindle self-organization, as well as how the forces acting in the spindle are generated, balanced, and regulated.

The Physics of the Metaphase Spindle.

PubMed

Oriola, David; Needleman, Daniel J; Brugués, Jan

2018-05-20

The assembly of the mitotic spindle and the subsequent segregation of sister chromatids are based on the self-organized action of microtubule filaments, motor proteins, and other microtubule-associated proteins, which constitute the fundamental force-generating elements in the system. Many of the components in the spindle have been identified, but until recently it remained unclear how their collective behaviors resulted in such a robust bipolar structure. Here, we review the current understanding of the physics of the metaphase spindle that is only now starting to emerge.

Theory of meiotic spindle assembly

NASA Astrophysics Data System (ADS)

Furthauer, Sebastian; Foster, Peter; Needleman, Daniel; Shelley, Michael

2016-11-01

The meiotic spindle is a biological structure that self assembles from the intracellular medium to separate chromosomes during meiosis. It consists of filamentous microtubule (MT) proteins that interact through the fluid in which they are suspended and via the associated molecules that orchestrate their behavior. We aim to understand how the interplay between fluid medium, MTs, and regulatory proteins allows this material to self-organize into the spindle's highly stereotyped shape. To this end we develop a continuum model that treats the spindle as an active liquid crystal with MT turnover. In this active material, molecular motors, such as dyneins which collect MT minus ends and kinesins which slide MTs past each other, generate active fluid and material stresses. Moreover nucleator proteins that are advected with and transported along MTs control the nucleation and depolymerization of MTs. This theory captures the growth process of meiotic spindles, their shapes, and the essential features of many perturbation experiments. It thus provides a framework to think about the physics of this complex biological suspension.

Differential sympathetic neural control of oxygenation in resting and exercising human skeletal muscle.

PubMed Central

Hansen, J; Thomas, G D; Harris, S A; Parsons, W J; Victor, R G

1996-01-01

Metabolic products of skeletal muscle contraction activate metaboreceptor muscle afferents that reflexively increase sympathetic nerve activity (SNA) targeted to both resting and exercising skeletal muscle. To determine effects of the increased sympathetic vasoconstrictor drive on muscle oxygenation, we measured changes in tissue oxygen stores and mitochondrial cytochrome a,a3 redox state in rhythmically contracting human forearm muscles with near infrared spectroscopy while simultaneously measuring muscle SNA with microelectrodes. The major new finding is that the ability of reflex-sympathetic activation to decrease muscle oxygenation is abolished when the muscle is exercised at an intensity > 10% of maximal voluntary contraction (MVC). During high intensity handgrip, (45% MVC), contraction-induced decreases in muscle oxygenation remained stable despite progressive metaboreceptor-mediated reflex increases in SNA. During mild to moderate handgrips (20-33% MVC) that do not evoke reflex-sympathetic activation, experimentally induced increases in muscle SNA had no effect on oxygenation in exercising muscles but produced robust decreases in oxygenation in resting muscles. The latter decreases were evident even during maximal metabolic vasodilation accompanying reactive hyperemia. We conclude that in humans sympathetic neural control of skeletal muscle oxygenation is sensitive to modulation by metabolic events in the contracting muscles. These events are different from those involved in either metaboreceptor muscle afferent activation or reactive hyperemia. PMID:8755671

[Permanent constrictions of the jaws (author's transl)].

PubMed

Dupuis, A; Michaud, J

1981-01-01

Permanent constrictions of the jaws are of various types depending on the site of the lesion: temporomaxillary ankylosis, extra-articular constrictions of bone, skin, muscle, or mucosal origin, and those arising from tumors. The commonest cause is injury, those due to infection being currently less frequently observed, which cannot be said for those of tumoral origin. The consequences are difficulty in taking foud and poor buccodental hygiene, while temporomaxillary ankylosis in children provokes mandibular growth disturbances. Surgical treatment is aimed at removing the constriction. Total resection of the ankylosed block is essential to avoid recurrences, while reeducation of buccal opening must be started early and continued for long periods in all cases.

Neural Contributions to Muscle Fatigue: From the Brain to the Muscle and Back Again

PubMed Central

Taylor, Janet L.; Amann, Markus; Duchateau, Jacques; Meeusen, Romain; Rice, Charles L.

2016-01-01

During exercise, there is a progressive reduction in the ability to produce muscle forces. Processes within the nervous system, as well as within the muscles contribute to this fatigue. In addition to impaired function of the motor system, sensations associated with fatigue, and impairment of homeostasis can contribute to impairment of performance during exercise. This review discusses some of the neural changes that accompany exercise and the development of fatigue. The role of brain monoaminergic neurotransmitter systems in whole-body endurance performance is discussed, particularly with regard to exercise in hot environments. Next, fatigue-related alterations in the neuromuscular pathway are discussed in terms of changes in motor unit firing, motoneuron excitability and motor cortical excitability. These changes have mostly been investigated during single-limb isometric contractions. Finally, the small-diameter muscle afferents that increase firing with exercise and fatigue are discussed. These afferents have roles in cardiovascular and respiratory responses to exercise, and in impairment of exercise performance through interaction with the motor pathway, as well as providing sensations of muscle discomfort. Thus, changes at all levels of the nervous system including the brain, spinal cord, motor output, sensory input and autonomic function occur during exercise and fatigue. The mix of influences and the importance of their contribution varies with the type of exercise being performed. PMID:27003703

Regulation of spindle integrity and mitotic fidelity by BCCIP

PubMed Central

Huhn, S C; Liu, J; Ye, C; Lu, H; Jiang, X; Feng, X; Ganesan, S; White, E; Shen, Z

2017-01-01

Centrosomes together with the mitotic spindle ensure the faithful distribution of chromosomes between daughter cells, and spindle orientation is a major determinant of cell fate during tissue regeneration. Spindle defects are not only an impetus of chromosome instability but are also a cause of developmental disorders involving defective asymmetric cell division. In this work, we demonstrate BCCIP, especially BCCIPα, as a previously unidentified component of the mitotic spindle pole and the centrosome. We demonstrate that BCCIP localizes proximal to the mother centriole and participates in microtubule organization and then redistributes to the spindle pole to ensure faithful spindle architecture. We find that BCCIP depletion leads to morphological defects, disoriented mitotic spindles, chromosome congression defects and delayed mitotic progression. Our study identifies BCCIP as a novel factor critical for microtubule regulation and explicates a mechanism utilized by BCCIP in tumor suppression. PMID:28394342

Changes in Afferent Activity After Spinal Cord Injury

PubMed Central

de Groat, William C.; Yoshimura, Naoki

2010-01-01

Aims To summarize the changes that occur in the properties of bladder afferent neurons following spinal cord injury. Methods Literature review of anatomical, immunohistochemical, and pharmacologic studies of normal and dysfunctional bladder afferent pathways. Results Studies in animals indicate that the micturition reflex is mediated by a spinobulbospinal pathway passing through coordination centers (periaqueductal gray and pontine micturition center) located in the rostral brain stem. This reflex pathway, which is activated by small myelinated (Aδ) bladder afferent nerves, is in turn modulated by higher centers in the cerebral cortex involved in the voluntary control of micturition. Spinal cord injury at cervical or thoracic levels disrupts voluntary voiding, as well as the normal reflex pathways that coordinate bladder and sphincter function. Following spinal cord injury, the bladder is initially areflexic but then becomes hyperreflexic due to the emergence of a spinal micturition reflex pathway. The recovery of bladder function after spinal cord injury is dependent in part on the plasticity of bladder afferent pathways and the unmasking of reflexes triggered by unmyelinated, capsaicin-sensitive, C-fiber bladder afferent neurons. Plasticity is associated with morphologic, chemical, and electrical changes in bladder afferent neurons and appears to be mediated in part by neurotrophic factors released in the spinal cord and the peripheral target organs. Conclusions Spinal cord injury at sites remote from the lumbosacral spinal cord can indirectly influence properties of bladder afferent neurons by altering the function and chemical environment in the bladder or the spinal cord. PMID:20025033

Intramedullary spindle cell hemangioma: case report.

PubMed

Nasser, Rani; Ashayeri, Kimberly; Legatt, Alan D; Houten, John K

2016-09-01

The authors describe the case of a 48-year-old man found to have the first reported intramedullary spinal cord spindle cell hemangioma. Previous research indicates that spindle cell hemangiomas are rarely found in the spine. Only 3 previous cases exist, all in the intradural, extramedullary space. In the present case, gross-total resection of the tumor was possible with no loss of function from baseline. This report presents the successful resection of the first reported intramedullary spindle cell hemangioma and reports 4-month follow-up, demonstrating the biological behavior of this rare tumor.

21 CFR 872.2060 - Jaw tracking device.

Code of Federal Regulations, 2014 CFR

2014-04-01

...) MEDICAL DEVICES DENTAL DEVICES Diagnostic Devices § 872.2060 Jaw tracking device. (a) Jaw tracking device... Controls Guidance Document: Dental Sonography and Jaw Tracking Devices.” [68 FR 67367, Dec. 2, 2003] ...

Differential central projections of vestibular afferents in pigeons

NASA Technical Reports Server (NTRS)

Dickman, J. D.; Fang, Q.

1996-01-01

The question of whether a differential distribution of vestibular afferent information to central nuclear neurons is present in pigeons was studied using neural tracer compounds. Discrete tracing of afferent fibers innervating the individual semicircular canal and otolith organs was produced by sectioning individual branches of the vestibular nerve that innervate the different receptor organs and applying crystals of horseradish peroxidase, or a horseradish peroxidase/cholera toxin mixture, or a biocytin compound for neuronal uptake and transport. Afferent fibers and their terminal distributions within the brainstem and cerebellum were visualized subsequently. Discrete areas in the pigeon central nervous system that receive primary vestibular input include the superior, dorsal lateral, ventral lateral, medial, descending, and tangential vestibular nuclei; the A and B groups; the intermediate, medial, and lateral cerebellar nuclei; and the nodulus, the uvula, and the paraflocculus. Generally, the vertical canal afferents projected heavily to medial regions in the superior and descending vestibular nuclei as well as the A group. Vertical canal projections to the medial and lateral vestibular nuclei were observed but were less prominent. Horizontal canal projections to the superior and descending vestibular nuclei were much more centrally located than those of the vertical canals. A more substantial projection to the medial and lateral vestibular nuclei was seen with horizontal canal afferents compared to vertical canal fibers. Afferents innervating the utricle and saccule terminated generally in the lateral regions of all vestibular nuclei in areas that were separate from the projections of the semicircular canals. In addition, utricular fibers projected to regions in the vestibular nuclei that overlapped with the horizontal semicircular canal terminal fields, whereas saccular afferents projected to regions that received vertical canal fiber terminations. Lagenar

Sleep spindles and intelligence: evidence for a sexual dimorphism.

PubMed

Ujma, Péter P; Konrad, Boris Nikolai; Genzel, Lisa; Bleifuss, Annabell; Simor, Péter; Pótári, Adrián; Körmendi, János; Gombos, Ferenc; Steiger, Axel; Bódizs, Róbert; Dresler, Martin

2014-12-03

Sleep spindles are thalamocortical oscillations in nonrapid eye movement sleep, which play an important role in sleep-related neuroplasticity and offline information processing. Sleep spindle features are stable within and vary between individuals, with, for example, females having a higher number of spindles and higher spindle density than males. Sleep spindles have been associated with learning potential and intelligence; however, the details of this relationship have not been fully clarified yet. In a sample of 160 adult human subjects with a broad IQ range, we investigated the relationship between sleep spindle parameters and intelligence. In females, we found a positive age-corrected association between intelligence and fast sleep spindle amplitude in central and frontal derivations and a positive association between intelligence and slow sleep spindle duration in all except one derivation. In males, a negative association between intelligence and fast spindle density in posterior regions was found. Effects were continuous over the entire IQ range. Our results demonstrate that, although there is an association between sleep spindle parameters and intellectual performance, these effects are more modest than previously reported and mainly present in females. This supports the view that intelligence does not rely on a single neural framework, and stronger neural connectivity manifesting in increased thalamocortical oscillations in sleep is one particular mechanism typical for females but not males. Copyright © 2014 the authors 0270-6474/14/3416358-11$15.00/0.

Influence of glutamate-evoked pain and sustained elevated muscle activity on blood oxygenation in the human masseter muscle.

PubMed

Suzuki, Shunichi; Arima, Taro; Kitagawa, Yoshimasa; Svensson, Peter; Castrillon, Eduardo

2017-12-01

This study aimed to investigate the effect of glutamate-evoked masseter muscle pain on intramuscular oxygenation during rest and sustained elevated muscle activity (SEMA). Seventeen healthy individuals participated in two sessions in which they were injected with glutamate and saline in random order. Each session was divided into three, 10-min periods. During the first (period 1) and the last (period 3) 10-min periods, participants performed five intercalated 1-min bouts of masseter SEMA with 1-min periods of 'rest'. At onset of the second 10-min period, glutamate (0.5 ml, 1 M; Ajinomoto, Tokyo, Japan) or isotonic saline (0.5 ml; 0.9%) was injected into the masseter muscle and the participants kept the muscle relaxed in a resting position for 10 min (period 2). The hemodynamic characteristics of the masseter muscle were recorded simultaneously during the experiment by a laser blood-oxygenation monitor. The results demonstrated that glutamate injections caused significant levels of self-reported pain in the masseter muscle; however, this nociceptive input did not have robust effects on intramuscular oxygenation during rest or SEMA tasks. Interestingly, these findings suggest an uncoupling between acute nociceptive activity and hemodynamic parameters in both resting and low-level active jaw muscles. Further studies are needed to explore the pathophysiological significance of blood-flow changes for persistent jaw-muscle pain conditions. © 2017 Eur J Oral Sci.

Sleep spindles in humans: insights from intracranial EEG and unit recordings

PubMed Central

Andrillon, Thomas; Nir, Yuval; Staba, Richard J.; Ferrarelli, Fabio; Cirelli, Chiara; Tononi, Giulio; Fried, Itzhak

2012-01-01

Sleep spindles are an electroencephalographic (EEG) hallmark of non-rapid eye movement (NREM) sleep and are believed to mediate many sleep-related functions, from memory consolidation to cortical development. Spindles differ in location, frequency, and association with slow waves, but whether this heterogeneity may reflect different physiological processes and potentially serve different functional roles remains unclear. Here we utilized a unique opportunity to record intracranial depth EEG and single-unit activity in multiple brain regions of neurosurgical patients to better characterize spindle activity in human sleep. We find that spindles occur across multiple neocortical regions, and less frequently also in the parahippocampal gyrus and hippocampus. Most spindles are spatially restricted to specific brain regions. In addition, spindle frequency is topographically organized with a sharp transition around the supplementary motor area between fast (13-15Hz) centroparietal spindles often occurring with slow wave up-states, and slow (9-12Hz) frontal spindles occurring 200ms later on average. Spindle variability across regions may reflect the underlying thalamocortical projections. We also find that during individual spindles, frequency decreases within and between regions. In addition, deeper sleep is associated with a reduction in spindle occurrence and spindle frequency. Frequency changes between regions, during individual spindles, and across sleep may reflect the same phenomenon, the underlying level of thalamocortical hyperpolarization. Finally, during spindles neuronal firing rates are not consistently modulated, although some neurons exhibit phase-locked discharges. Overall, anatomical considerations can account well for regional spindle characteristics, while variable hyperpolarization levels can explain differences in spindle frequency. PMID:22159098

Brownian dynamics simulation of fission yeast mitotic spindle formation

NASA Astrophysics Data System (ADS)

Edelmaier, Christopher

2014-03-01

The mitotic spindle segregates chromosomes during mitosis. The dynamics that establish bipolar spindle formation are not well understood. We have developed a computational model of fission-yeast mitotic spindle formation using Brownian dynamics and kinetic Monte Carlo methods. Our model includes rigid, dynamic microtubules, a spherical nuclear envelope, spindle pole bodies anchored in the nuclear envelope, and crosslinkers and crosslinking motor proteins. Crosslinkers and crosslinking motor proteins attach and detach in a grand canonical ensemble, and exert forces and torques on the attached microtubules. We have modeled increased affinity for crosslinking motor attachment to antiparallel microtubule pairs, and stabilization of microtubules in the interpolar bundle. We study parameters controlling the stability of the interpolar bundle and assembly of a bipolar spindle from initially adjacent spindle-pole bodies.

Ia Afferent input alters the recruitment thresholds and firing rates of single human motor units.

PubMed

Grande, G; Cafarelli, E

2003-06-01

Vibration of the patellar tendon recruits motor units in the knee extensors via excitation of muscle spindles and subsequent Ia afferent input to the alpha-motoneuron pool. Our first purpose was to determine if the recruitment threshold and firing rate of the same motor unit differed when recruited involuntarily via reflex or voluntarily via descending spinal pathways. Although Ia input is excitatory to the alpha-motoneuron pool, it has also been shown paradoxically to inhibit itself. Our second purpose was to determine if vibration of the patellar tendon during a voluntary knee extension causes a change in the firing rate of already recruited motor units. In the first protocol, 10 subjects voluntarily reproduced the same isometric force profile of the knee extensors that was elicited by vibration of the patellar tendon. Single motor unit recordings from the vastus lateralis (VL) were obtained with tungsten microelectrodes and unitary behaviour was examined during both reflex and voluntary knee extensions. Recordings from 135 single motor units showed that both recruitment thresholds and firing rates were lower during reflex contractions. In the second protocol, 7 subjects maintained a voluntary knee extension at 30 N for approximately 40-45 s. Three bursts of patellar tendon vibration were superimposed at regular intervals throughout the contraction and changes in the firing rate of already recruited motor units were examined. A total of 35 motor units were recorded and each burst of superimposed vibration caused a momentary reduction in the firing rates and recruitment of additional units. Our data provide evidence that Ia input modulates the recruitment thresholds and firing rates of motor units providing more flexibility within the neuromuscular system to grade force at low levels of force production.

Vestibular afferent responses to linear accelerations in the alert squirrel monkey

NASA Technical Reports Server (NTRS)

Somps, Christopher J.; Schor, Robert H.; Tomko, David L.

1994-01-01

The spontaneous activity of 40 otolith afferents and 44 canal afferents was recorded in 4 alert, intact squirrel monkeys. Polarization vectors and response properties of otolith afferents were determined during static re-orientations relative to gravity and during Earth-horizontal, sinusoidal, linear oscillations. Canal afferents were tested for sensitivity to linear accelerations. For regular otolith afferents, a significant correlation between upright discharge rate and sensitivity to dynamic acceleration in the horizontal plane was observed. This correlation was not present in irregular units. The sensitivity of otolith afferents to both static tilts and dynamic linear acceleration was much greater in irregularly discharging units than in regularly discharging units. The spontaneous activity and static and dynamic response properties of regularly discharging otolith afferents were similar to those reported in barbiturate-anesthetized squirrel monkeys. Irregular afferents also had similar dynamic response properties when compared to anesthetized monkeys. However, this sample of irregular afferents in alert animals had higher resting discharge rates and greater sensitivity to static tilts. The majority of otolith polarization vectors were oriented near the horizontal in the plane of the utricular maculae; however, directions of maximum sensitivity were different during dynamic and static testing. Canal afferents were not sensitive to static tilts or linear oscillations of the head.

Muscular responses appear to be associated with existence of kinesthetic perception during combination of tendon co-vibration and motor imagery.

PubMed

Shibata, Eriko; Kaneko, Fuminari; Katayose, Masaki

2017-11-01

The afferent inputs from peripheral sensory receptors and efferent signals from the central nervous system that underlie intentional movement can contribute to kinesthetic perception. Previous studies have revealed that tendon vibration to wrist muscles elicits an excitatory response-known as the antagonist vibratory response-in muscles antagonistic to the vibrated muscles. Therefore, the present study aimed to further investigate the effect of tendon vibration combined with motor imagery on kinesthetic perception and muscular activation. Two vibrators were applied to the tendons of the left flexor carpi radialis and extensor carpi radialis. When the vibration frequency was the same between flexors and extensors, no participant perceived movement and no muscle activity was induced. When participants imagined flexing their wrists during tendon vibration, the velocity of perceptual flexion movement increased. Furthermore, muscle activity of the flexor increased only during motor imagery. These results demonstrate that kinesthetic perception can be induced during the combination of motor imagery and co-vibration, even with no experience of kinesthetic perception from an afferent input with co-vibration at the same frequency. Although motor responses were observed during combined co-vibration and motor imagery, no such motor responses were recorded during either co-vibration alone or motor imagery alone, suggesting that muscular responses during the combined condition are associated with kinesthetic perception. Thus, the present findings indicate that kinesthetic perception is influenced by the interaction between afferent input from muscle spindles and the efferent signals that underlie intentional movement. We propose that the physiological behavior resulting from kinesthetic perception affects the process of modifying agonist muscle activity, which will be investigated in a future study.

Topological defects in confined populations of spindle-shaped cells

NASA Astrophysics Data System (ADS)

Duclos, Guillaume; Erlenkämper, Christoph; Joanny, Jean-François; Silberzan, Pascal

2017-01-01

Most spindle-shaped cells (including smooth muscles and sarcomas) organize in vivo into well-aligned `nematic’ domains, creating intrinsic topological defects that may be used to probe the behaviour of these active nematic systems. Active non-cellular nematics have been shown to be dominated by activity, yielding complex chaotic flows. However, the regime in which live spindle-shaped cells operate, and the importance of cell-substrate friction in particular, remains largely unexplored. Using in vitro experiments, we show that these active cellular nematics operate in a regime in which activity is effectively damped by friction, and that the interaction between defects is controlled by the system’s elastic nematic energy. Due to the activity of the cells, these defects behave as self-propelled particles and pairwise annihilate until all displacements freeze as cell crowding increases. When confined in mesoscopic circular domains, the system evolves towards two identical +1/2 disclinations facing each other. The most likely reduced positions of these defects are independent of the size of the disk, the cells’ activity or even the cell type, but are well described by equilibrium liquid crystal theory. These cell-based systems thus operate in a regime more stable than other active nematics, which may be necessary for their biological function.

Neurogenic vasoreactive response of human internal thoracic artery smooth muscle.

PubMed

Canver, C C; Cooler, S D; Saban, R

1997-09-01

The interaction between primary afferent neurons containing neuropeptides and the vascular smooth muscle is incompletely understood. To explore the function of perivascular afferent neurons and to determine whether they produce local effects on vascular smooth muscle cells, we investigated the effects of acute capsaicin and substance P administration in vitro on human internal thoracic arteries (ITA). Vessels were obtained from patients undergoing coronary bypass or from multiorgan transplant donors. Fourteen ITA segments (5 mm wide) were suspended as rings between two stainless-steel stirrups in water-jacketed (37 degrees C) tissue baths under 2.5 to 3 g of basal tension. The tissue baths contained 10 mL physiological salt solution (PSS) of the following composition (mM): NaCl, 119; KCl, 4.7; NaH2PO4, 1.0; MgCl2, 0.5; CaCl2, 2.5; NaHCO3, 25; and glucose, 11; aerated continuously with 95% O2 and 5% CO2. Peptidase inhibitors (phosphoramidon and captopril) were added to PSS to decrease peptide degradation. Mechanical responses were measured isometrically and recorded on a polygraph via isotonic force transducers. Vessels were preconstricted with submaximal concentrations of norepinephrine. After the tension had stabilized, substance P or capsaicin was added cumulatively to the tissue bath. At the end of the experiments, the viability of ITA was verified by its responses to endothelial-dependent (acetylcholine) and endothelial-independent (sodium nitroprusside) vasodilators. In the endothelium-intact ITA segments, substance P produced relaxation of ITA smooth muscle while it induced slight contraction when the ITA was devoid of its endothelium (P = 0.0585). The addition of capsaicin to human ITA primarily produced contractile effects on the developed smooth muscle force. The capsaicin-induced contraction of the ITA smooth muscle was independent of endothelial cell integrity, although contraction was greater in the endothelium-intact ITA segments (P = 0.0165). The

Spatiotemporal characteristics of sleep spindles depend on cortical location.

PubMed

Piantoni, Giovanni; Halgren, Eric; Cash, Sydney S

2017-02-01

Since their discovery almost one century ago, sleep spindles, 0.5-2s long bursts of oscillatory activity at 9-16Hz during NREM sleep, have been thought to be global and relatively uniform throughout the cortex. Recent work, however, has brought this concept into question but it remains unclear to what degree spindles are global or local and if their properties are uniform or location-dependent. We addressed this question by recording sleep in eight patients undergoing evaluation for epilepsy with intracranial electrocorticography, which combines high spatial resolution with extensive cortical coverage. We find that spindle characteristics are not uniform but are strongly influenced by the underlying cortical regions, particularly for spindle density and fundamental frequency. We observe both highly isolated and spatially distributed spindles, but in highly skewed proportions: while most spindles are restricted to one or very few recording channels at any given time, there are spindles that occur over widespread areas, often involving lateral prefrontal cortices and superior temporal gyri. Their co-occurrence is affected by a subtle but significant propagation of spindles from the superior prefrontal regions and the temporal cortices towards the orbitofrontal cortex. This work provides a brain-wide characterization of sleep spindles as mostly local graphoelements with heterogeneous characteristics that depend on the underlying cortical area. We propose that the combination of local characteristics and global organization reflects the dual properties of the thalamo-cortical generators and provides a flexible framework to support the many functions ascribed to sleep in general and spindles specifically. Copyright © 2016 Elsevier Inc. All rights reserved.

Peripheral innervation patterns of vestibular nerve afferents in the bullfrog utriculus

NASA Technical Reports Server (NTRS)

Baird, Richard A.; Schuff, N. R.

1994-01-01

Vestibular nerve afferents innervating the bullfrog utriculus differ in their response dynamics and sensitivity to natural stimulation. They also supply hair cells that differ markedly in hair bundle morphology. To examine the peripheral innervation patterns of individual utricular afferents more closely, afferent fibers were labeled by the extracellular injection of horseradish peroxidase (HRP) into the vestibular nerve after sectioning the vestibular nerve medial to Scarpa's ganglion to allow the degeneration of sympathetic and efferent fibers. The peripheral arborizations of individual afferents were then correlated with the diameters of their parent axons, the regions of the macula they innervate, and the number and type of hair cells they supply. The utriculus is divided by the striola, a narrow zone of distinctive morphology, into media and lateral parts. Utiricular afferents were classified as striolar or extrastriolar according to the epithelial entrance of their parent axons and the location of their terminal fields. In general, striolar afferents had thicker parent axons, fewer subepithelial bifurcations, larger terminal fields, and more synaptic endings than afferents in extrstriolar regions. Afferents in a juxtastriolar zone, immediately adjacent to the medial striola, had innervation patterns transitional between those in the striola and more peripheral parts of the medial extrastriola. moast afferents innervated only a single macular zone. The terminal fields of striolar afferents, with the notable exception of a few afferents with thin parent axons, were generally confined to one side of the striola. Hair cells in the bullfrog utriculus have perviously been classified into four types based on hair bundle morphology. Afferents in the extrastriolar and juxtastriolar zones largely or exclusively innervated Type B hair cells, the predominant hair cell type in the utricular macula. Striolar afferents supplied a mixture of four hair cell types, but largely

Co-contraction behaviour of masticatory and neck muscles during tooth grinding.

PubMed

Giannakopoulos, N N; Schindler, H J; Hellmann, D

2018-07-01

The objective of this study was to analyse the co-contraction behaviour of jaw and neck muscles during force-controlled experimental grinding in the supine position. Twelve symptom-free subjects were enrolled in the experimental study. Electromyographic (EMG) activity of semispinalis capitis, splenius capitis and levator scapulae muscles was recorded bilaterally with intramuscular fine-wire electrodes, whereas that of sternocleidomastoideus, infrahyoidal, suprahyoidal, masseter and anterior temporalis muscles were registered with surface electrodes. EMG and force measurements were performed during tasks simulating tooth grinding on custom-made intraoral metal splints. The mean EMG activity normalised by maximum voluntary contraction (% MVC) of each of the neck muscles studied during grinding was analysed and compared with previous data from jaw clenching at identical force (100 N) and (supine) position. The occurrence of low-level, long-lasting tonic activation (LLTA) of motor units was also documented. The mean three-dimensional force vector of the grinding forces was 106 ± 74 N. In the frontal plane, the incline to the midsagittal plane ranged between 10° and 15°. In the midsagittal plane, the incline to the frontal plane was negligibly small. Posterior neck muscle activity during grinding ranged between 4.5% and 12% MVC and during clenching with 100 N between 1.8% and 9.9% MVC. Masticatory muscle activity during grinding ranged between 17% and 21% MVC for contralateral masseter and ipsilateral temporalis and between 4% and 6.5% for ipsilateral masseter and contralateral temporalis. LLTA had an average duration of 195 ± 10 seconds. The findings from this study do not support pathophysiological muscle chain theories postulating simple biomechanical coupling of neck and jaw muscles. Co-contractions of neck and masticatory muscles may instead occur as a result of complex neurophysiological interactions. © 2018 John Wiley & Sons Ltd.

Analysis and topology optimization design of high-speed driving spindle

NASA Astrophysics Data System (ADS)

Wang, Zhilin; Yang, Hai

2018-04-01

The three-dimensional model of high-speed driving spindle is established by using SOLIDWORKS. The model is imported through the interface of ABAQUS, A finite element analysis model of high-speed driving spindle was established by using spring element to simulate bearing boundary condition. High-speed driving spindle for the static analysis, the spindle of the stress, strain and displacement nephogram, and on the basis of the results of the analysis on spindle for topology optimization, completed the lightweight design of high-speed driving spindle. The design scheme provides guidance for the design of axial parts of similar structures.

Developmental finite element analysis of cichlid pharyngeal jaws: Quantifying the generation of a key innovation.

PubMed

Peterson, Tim; Müller, Gerd B

2018-01-01

Advances in imaging and modeling facilitate the calculation of biomechanical forces in biological specimens. These factors play a significant role during ontogenetic development of cichlid pharyngeal jaws, a key innovation responsible for one of the most prolific species diversifications in recent times. MicroCT imaging of radiopaque-stained vertebrate embryos were used to accurately capture the spatial relationships of the pharyngeal jaw apparatus in two cichlid species (Haplochromis elegans and Amatitlania nigrofasciata) for the purpose of creating a time series of developmental stages using finite element models, which can be used to assess the effects of biomechanical forces present in a system at multiple points of its ontogeny. Changes in muscle vector orientations, bite forces, force on the neurocranium where cartilage originates, and stress on upper pharyngeal jaws are analyzed in a comparative context. In addition, microCT scanning revealed the presence of previously unreported cement glands in A. nigrofasciata. The data obtained provide an underrepresented dimension of information on physical forces present in developmental processes and assist in interpreting the role of developmental dynamics in evolution.

Developmental finite element analysis of cichlid pharyngeal jaws: Quantifying the generation of a key innovation

PubMed Central

Müller, Gerd B.

2018-01-01

Advances in imaging and modeling facilitate the calculation of biomechanical forces in biological specimens. These factors play a significant role during ontogenetic development of cichlid pharyngeal jaws, a key innovation responsible for one of the most prolific species diversifications in recent times. MicroCT imaging of radiopaque-stained vertebrate embryos were used to accurately capture the spatial relationships of the pharyngeal jaw apparatus in two cichlid species (Haplochromis elegans and Amatitlania nigrofasciata) for the purpose of creating a time series of developmental stages using finite element models, which can be used to assess the effects of biomechanical forces present in a system at multiple points of its ontogeny. Changes in muscle vector orientations, bite forces, force on the neurocranium where cartilage originates, and stress on upper pharyngeal jaws are analyzed in a comparative context. In addition, microCT scanning revealed the presence of previously unreported cement glands in A. nigrofasciata. The data obtained provide an underrepresented dimension of information on physical forces present in developmental processes and assist in interpreting the role of developmental dynamics in evolution. PMID:29320528

Swiveling Lathe Jaw Concept for Holding Irregular Pieces

NASA Technical Reports Server (NTRS)

David, J.

1966-01-01

Clamp holds irregularly shaped pieces in lathe chuck without damage and eliminates excessive time in selecting optimum mounting. Interchangeable jaws ride in standard jaw slots but swivel so that the jaw face bears evenly against the workpiece regardless of contour. The jaws can be used on both engine and turret lathes.

Akap350 Recruits Eb1 to The Spindle Poles, Ensuring Proper Spindle Orientation and Lumen Formation in 3d Epithelial Cell Cultures.

PubMed

Almada, Evangelina; Tonucci, Facundo M; Hidalgo, Florencia; Ferretti, Anabela; Ibarra, Solange; Pariani, Alejandro; Vena, Rodrigo; Favre, Cristián; Girardini, Javier; Kierbel, Arlinet; Larocca, M Cecilia

2017-11-02

The organization of epithelial cells to form hollow organs with a single lumen requires the accurate three-dimensional arrangement of cell divisions. Mitotic spindle orientation is defined by signaling pathways that provide molecular links between specific spots at the cell cortex and astral microtubules, which have not been fully elucidated. AKAP350 is a centrosomal/Golgi scaffold protein, implicated in the regulation of microtubule dynamics. Using 3D epithelial cell cultures, we found that cells with decreased AKAP350 expression (AKAP350KD) formed polarized cysts with abnormal lumen morphology. Analysis of mitotic cells in AKAP350KD cysts indicated defective spindle alignment. We established that AKAP350 interacts with EB1, a microtubule associated protein that regulates spindle orientation, at the spindle poles. Decrease of AKAP350 expression lead to a significant reduction of EB1 levels at spindle poles and astral microtubules. Conversely, overexpression of EB1 rescued the defective spindle orientation induced by deficient AKAP350 expression. The specific delocalization of the AKAP350/EB1complex from the centrosome decreased EB1 levels at astral microtubules and lead to the formation of 3D-organotypic structures which resembled AKAP350KD cysts. We conclude that AKAP350 recruits EB1 to the spindle poles, ensuring EB1 presence at astral microtubules and proper spindle orientation during epithelial morphogenesis.

Combination spindle-drive system for high precision machining

DOEpatents

Gerth, Howard L.

1977-07-26

A combination spindle-drive is provided for fabrication of optical quality surface finishes. Both the spindle-and-drive utilize the spindle bearings for support, thereby removing the conventional drive-means bearings as a source of vibration. An airbearing spindle is modified to carry at the drive end a highly conductive cup-shaped rotor which is aligned with a stationary stator to produce torque in the cup-shaped rotor through the reaction of eddy currents induced in the rotor. This arrangement eliminates magnetic attraction forces and all force is in the form of torque on the cup-shaped rotor.

Oligosynaptic inhibition of group Ia afferents from brachioradialis to triceps brachii motor neurons in humans.

PubMed

Sato, Toshiaki; Nito, Mitsuhiro; Suzuki, Katsuhiko; Fujii, Hiromi; Hashizume, Wataru; Miyasaka, Takuji; Shindo, Masaomi; Naito, Akira

2018-01-01

This study examines effects of low-threshold afferents from the brachioradialis (BR) on excitability of triceps brachii (TB) motor neurons in humans. We evaluated the effects using a post stimulus time histogram (PSTH) and electromyogram averaging (EMG-A) methods in 13 healthy human participants. Electrical conditioning stimulation to the radial nerve branch innervating BR with the intensity below the motor threshold was delivered. In the PSTH study, the stimulation produced a trough (inhibition) in 36/69 TB motor units for all the participants. A cutaneous stimulation never provoked such inhibition. The central latency of the inhibition was 1.5 ± 0.5 ms longer than that of the homonymous facilitation. In the EMG-A study, the stimulation produced inhibition in EMG-A of TB in all participants. The inhibition diminished with a tonic vibration stimulation to BR. These findings suggest that oligosynaptic inhibition mediated by group Ia afferents from BR to TB exists in humans. Muscle Nerve 57: 122-128, 2018. © 2017 Wiley Periodicals, Inc.

Monitoring Method of Cutting Force by Using Additional Spindle Sensors

NASA Astrophysics Data System (ADS)

Sarhan, Ahmed Aly Diaa; Matsubara, Atsushi; Sugihara, Motoyuki; Saraie, Hidenori; Ibaraki, Soichi; Kakino, Yoshiaki

This paper describes a monitoring method of cutting forces for end milling process by using displacement sensors. Four eddy-current displacement sensors are installed on the spindle housing of a machining center so that they can detect the radial motion of the rotating spindle. Thermocouples are also attached to the spindle structure in order to examine the thermal effect in the displacement sensing. The change in the spindle stiffness due to the spindle temperature and the speed is investigated as well. Finally, the estimation performance of cutting forces using the spindle displacement sensors is experimentally investigated by machining tests on carbon steel in end milling operations under different cutting conditions. It is found that the monitoring errors are attributable to the thermal displacement of the spindle, the time lag of the sensing system, and the modeling error of the spindle stiffness. It is also shown that the root mean square errors between estimated and measured amplitudes of cutting forces are reduced to be less than 20N with proper selection of the linear stiffness.

Electroencephalogram spindle activity during dexmedetomidine sedation and physiological sleep.

PubMed

Huupponen, E; Maksimow, A; Lapinlampi, P; Särkelä, M; Saastamoinen, A; Snapir, A; Scheinin, H; Scheinin, M; Meriläinen, P; Himanen, S-L; Jääskeläinen, S

2008-02-01

Dexmedetomidine, a selective alpha(2)-adrenoceptor agonist, induces a unique, sleep-like state of sedation. The objective of the present work was to study human electroencephalogram (EEG) sleep spindles during dexmedetomidine sedation and compare them with spindles during normal physiological sleep, to test the hypothesis that dexmedetomidine exerts its effects via normal sleep-promoting pathways. EEG was continuously recorded from a bipolar frontopolar-laterofrontal derivation with Entropy Module (GE Healthcare) during light and deep dexmedetomidine sedation (target-controlled infusions set at 0.5 and 3.2 ng/ml) in 11 healthy subjects, and during physiological sleep in 10 healthy control subjects. Sleep spindles were visually scored and quantitatively analyzed for density, duration, amplitude (band-pass filtering) and frequency content (matching pursuit approach), and compared between the two groups. In visual analysis, EEG activity during dexmedetomidine sedation was similar to physiological stage 2 (S2) sleep with slight to moderate amount of slow-wave activity and abundant sleep spindle activity. In quantitative EEG analyses, sleep spindles were similar during dexmedetomidine sedation and normal sleep. No statistically significant differences were found in spindle density, amplitude or frequency content, but the spindles during dexmedetomidine sedation had longer duration (mean 1.11 s, SD 0.14 s) than spindles in normal sleep (mean 0.88 s, SD 0.14 s; P=0.0014). Analysis of sleep spindles shows that dexmedetomidine produces a state closely resembling physiological S2 sleep in humans, which gives further support to earlier experimental evidence for activation of normal non-rapid eye movement sleep-promoting pathways by this sedative agent.

Optimal design of high-speed loading spindle based on ABAQUS

NASA Astrophysics Data System (ADS)

Yang, Xudong; Dong, Yu; Ge, Qingkuan; Yang, Hai

2017-12-01

The three-dimensional model of high-speed loading spindle is established by using ABAQUS’s modeling module. A finite element analysis model of high-speed loading spindle was established by using spring element to simulate bearing boundary condition. The static and dynamic performance of the spindle structure with different specifications of the rectangular spline and the different diameter neck of axle are studied in depth, and the influence of different spindle span on the static and dynamic performance of the high-speed loading spindle is studied. Finally, the optimal structure of the high-speed loading spindle is obtained. The results provide a theoretical basis for improving the overall performance of the test-bed

Activation of GLP-1 receptors on vascular smooth muscle cells reduces the autoregulatory response in afferent arterioles and increases renal blood flow.

PubMed

Jensen, Elisa P; Poulsen, Steen S; Kissow, Hannelouise; Holstein-Rathlou, Niels-Henrik; Deacon, Carolyn F; Jensen, Boye L; Holst, Jens J; Sorensen, Charlotte M

2015-04-15

Glucagon-like peptide (GLP)-1 has a range of extrapancreatic effects, including renal effects. The mechanisms are poorly understood, but GLP-1 receptors have been identified in the kidney. However, the exact cellular localization of the renal receptors is poorly described. The aim of the present study was to localize renal GLP-1 receptors and describe GLP-1-mediated effects on the renal vasculature. We hypothesized that renal GLP-1 receptors are located in the renal microcirculation and that activation of these affects renal autoregulation and increases renal blood flow. In vivo autoradiography using (125)I-labeled GLP-1, (125)I-labeled exendin-4 (GLP-1 analog), and (125)I-labeled exendin 9-39 (GLP-1 receptor antagonist) was performed in rodents to localize specific GLP-1 receptor binding. GLP-1-mediated effects on blood pressure, renal blood flow (RBF), heart rate, renin secretion, urinary flow rate, and Na(+) and K(+) excretion were investigated in anesthetized rats. Effects of GLP-1 on afferent arterioles were investigated in isolated mouse kidneys. Specific binding of (125)I-labeled GLP-1, (125)I-labeled exendin-4, and (125)I-labeled exendin 9-39 was observed in the renal vasculature, including afferent arterioles. Infusion of GLP-1 increased blood pressure, RBF, and urinary flow rate significantly in rats. Heart rate and plasma renin concentrations were unchanged. Exendin 9-39 inhibited the increase in RBF. In isolated murine kidneys, GLP-1 and exendin-4 significantly reduced the autoregulatory response of afferent arterioles in response to stepwise increases in pressure. We conclude that GLP-1 receptors are located in the renal vasculature, including afferent arterioles. Activation of these receptors reduces the autoregulatory response of afferent arterioles to acute pressure increases and increases RBF in normotensive rats. Copyright © 2015 the American Physiological Society.

CENP-W Plays a Role in Maintaining Bipolar Spindle Structure

PubMed Central

Kaczmarczyk, Agnieszka; Sullivan, Kevin F.

2014-01-01

The CENP-W/T complex was previously reported to be required for mitosis. HeLa cells depleted of CENP-W displayed profound mitotic defects, with mitotic timing delay, disorganized prometaphases and multipolar spindles as major phenotypic consequences. In this study, we examined the process of multipolar spindle formation induced by CENP-W depletion. Depletion of CENP-W in HeLa cells labeled with histone H2B and tubulin fluorescent proteins induced rapid fragmentation of originally bipolar spindles in a high proportion of cells. CENP-W depletion was associated with depletion of Hec1 at kinetochores. The possibility of promiscuous centrosomal duplication was ruled out by immunofluorescent examination of centrioles. However, centrioles were frequently observed to be abnormally split. In addition, a large proportion of the supernumerary poles lacked centrioles, but were positively stained with different centrosomal markers. These observations suggested that perturbation in spindle force distribution caused by defective kinetochores could contribute to a mechanical mechanism for spindle pole disruption. ‘Spindle free’ nocodazole arrested cells did not exhibit pole fragmentation after CENP-W depletion, showing that pole fragmentation is microtubule dependent. Inhibition of centrosome separation by monastrol reduced the incidence of spindle pole fragmentation, indicating that Eg5 plays a role in spindle pole disruption. Surprisingly, CENP-W depletion rescued the monopolar spindle phenotype of monastrol treatment, with an increased frequency of bipolar spindles observed after CENP-W RNAi. We overexpressed the microtubule cross-linking protein TPX2 to create spindle poles stabilized by the microtubule cross-linking activity of TPX2. Spindle pole fragmentation was suppressed in a TPX2-dependent fashion. We propose that CENP-W, by influencing proper kinetochore assembly, particularly microtubule docking sites, can confer spindle pole resistance to traction forces exerted

Modal identification of spindle-tool unit in high-speed machining

NASA Astrophysics Data System (ADS)

Gagnol, Vincent; Le, Thien-Phu; Ray, Pascal

2011-10-01

The accurate knowledge of high-speed motorised spindle dynamic behaviour during machining is important in order to ensure the reliability of machine tools in service and the quality of machined parts. More specifically, the prediction of stable cutting regions, which is a critical requirement for high-speed milling operations, requires the accurate estimation of tool/holder/spindle set dynamic modal parameters. These estimations are generally obtained through Frequency Response Function (FRF) measurements of the non-rotating spindle. However, significant changes in modal parameters are expected to occur during operation, due to high-speed spindle rotation. The spindle's modal variations are highlighted through an integrated finite element model of the dynamic high-speed spindle-bearing system, taking into account rotor dynamics effects. The dependency of dynamic behaviour on speed range is then investigated and determined with accuracy. The objective of the proposed paper is to validate these numerical results through an experiment-based approach. Hence, an experimental setup is elaborated to measure rotating tool vibration during the machining operation in order to determine the spindle's modal frequency variation with respect to spindle speed in an industrial environment. The identification of natural frequencies of the spindle under rotating conditions is challenging, due to the low number of sensors and the presence of many harmonics in the measured signals. In order to overcome these issues and to extract the characteristics of the system, the spindle modes are determined through a 3-step procedure. First, spindle modes are highlighted using the Frequency Domain Decomposition (FDD) technique, with a new formulation at the considered rotating speed. These extracted modes are then analysed through the value of their respective damping ratios in order to separate the harmonics component from structural spindle natural frequencies. Finally, the stochastic

21 CFR 872.2060 - Jaw tracking device.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Jaw tracking device. 872.2060 Section 872.2060 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Diagnostic Devices § 872.2060 Jaw tracking device. (a) Jaw tracking device...

21 CFR 872.2060 - Jaw tracking device.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Jaw tracking device. 872.2060 Section 872.2060 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Diagnostic Devices § 872.2060 Jaw tracking device. (a) Jaw tracking device...

21 CFR 872.2060 - Jaw tracking device.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Jaw tracking device. 872.2060 Section 872.2060 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Diagnostic Devices § 872.2060 Jaw tracking device. (a) Jaw tracking device...

21 CFR 872.2060 - Jaw tracking device.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Jaw tracking device. 872.2060 Section 872.2060 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Diagnostic Devices § 872.2060 Jaw tracking device. (a) Jaw tracking device...

Immunohistochemical characterization of hemangiopericytomas and other spindle cell tumors in the dog.

PubMed

Pérez, J; Bautista, M J; Rollón, E; de Lara, F C; Carrasco, L; Martin de las Mulas, J

1996-07-01

The immunohistochemical expression of muscle actin has been studied in 45 canine hemangiopericytomas (CHP) using a monoclonal antibody (HHF35) and formalin-fixed, paraffin-embedded specimens. The distribution of vimentin, desmin, cytokeratins, lysozyme, factor VIII-related antigen, S-100 protein, and glial fibrillary acidic protein was studied both in CHP and in some canine soft-tissue neoplasms (seven fibrosarcomas, seven benign schwannomas, seven benign fibrous histiocytomas, and six leiomyosarcomas) used as controls for differential diagnosis. All CHP and control tumors expressed vimentin. Twenty-three CHP expressed muscle actin, whereas all control tumors analyzed were muscle actin-negative, with the exception of leiomyosarcomas. Among muscle actin- and vimentin-positive CHP, one case could be reclassified as leiomyosarcoma because it was desmin-positive, two cases expressed lysozyme, and nine cases expressed S-100 protein. Among muscle actin-negative and vimentin-positive CHP, seven expressed S-100 protein. In addition, S-100 protein was detected in five schwannomas. All CHP and control tumors analyzed were negative for cytokeratins, factor VIII-related antigen, and glial fibrillary acidic protein. Our results support the hypothesis of a pericytic origin of CHP, and suggest that muscle actin, desmin, vimentin, and lysozyme could be useful for the differential diagnosis of canine spindle cell tumors, but not all these neoplasms can be identified with these tumor tissue markers.

Physiological and ultrastructural analysis of elongating mitotic spindles reactivated in vitro

PubMed Central

1986-01-01

We have developed a simple procedure for isolating mitotic spindles from the diatom Stephanopyxis turris and have shown that they undergo anaphase spindle elongation in vitro upon addition of ATP. The isolated central spindle is a barrel-shaped structure with a prominent zone of microtubule overlap. After ATP addition greater than 75% of the spindle population undergoes distinct structural rearrangements: the spindles on average are longer and the two half-spindles are separated by a distinct gap traversed by only a small number of microtubules, the phase-dense material in the overlap zone is gone, and the peripheral microtubule arrays have depolymerized. At the ultrastructural level, we examined serial cross-sections of spindles after 1-, 5-, and 10-min incubations in reactivation medium. Microtubule depolymerization distal to the poles is confirmed by the increased number of incomplete, i.e., c-microtubule profiles specifically located in the region of overlap. After 10 min we see areas of reduced microtubule number which correspond to the gaps seen in the light microscope and an overall reduction in the number of half-spindle microtubules to about one-third the original number. The changes in spindle structure are highly specific for ATP, are dose-dependent, and do not occur with nonhydrolyzable nucleotide analogues. Spindle elongation and gap formation are blocked by 10 microM vanadate, equimolar mixtures of ATP and AMPPNP, and by sulfhydryl reagents. This process is not affected by nocodazole, erythro-9-[3-(2-hydroxynonyl)]adenine, cytochalasin D, and phalloidin. In the presence of taxol, the extent of spindle elongation is increased; however, distinct gaps still form between the two half- spindles. These results show that the response of isolated spindles to ATP is a complex process consisting of several discrete steps including initiation events, spindle elongation mechanochemistry, controlled central spindle microtubule plus-end depolymerization, and loss

Cognitive demand does not influence the responsiveness of homonymous Ia afferents pathway during postural dual task in young and elderly adults.

PubMed

Baudry, Stéphane; Gaillard, Vinciane

2014-02-01

This study was designed to investigate the influence of a cognitive task on the responsiveness of the homonymous Ia afferents pathway during upright standing in young and elderly adults. Twelve young and twelve elderly adults stood upright on a foam surface positioned over a force platform, and performed a colour-naming test (cognitive task) with two cognitive loads: congruent and incongruent colour conditions. The rate of correct response in naming colour (accuracy) and associated reaction time (RT) were recorded for the cognitive task. The excursion of the centre of pressure and surface electromyogramme (EMG) of leg muscles were measured. Modulation in the efficacy of homonymous Ia afferents to discharge spinal motor neurones was assessed by means of the Hoffmann (H) reflex method. The accuracy and RT were similar in the congruent condition between young and elderly adults (p > 0.05), and increased for both age groups in the incongruent condition, but more so for elderly adults (p = 0.014). In contrast, the H reflex amplitude did not change with the cognitive load. The excursions of the centre of pressure in the sagittal plane and muscle EMG did not vary with colour conditions in both groups (p > 0.05). This study indicates a lack of modulation in the efficacy of group Ia afferent to activate soleus motor neurones with the cognitive demand of a concurrent task during upright standing in young and elderly adults.

Do All Dinoflagellates have an Extranuclear Spindle?

PubMed

Moon, Eunyoung; Nam, Seung Won; Shin, Woongghi; Park, Myung Gil; Coats, D Wayne

2015-11-01

The syndinean dinoflagellates are a diverse assemblage of alveolate endoparasites that branch basal to the core dinoflagellates. Because of their phylogenetic position, the syndineans are considered key model microorganisms in understanding early evolution in the dinoflagellates. Closed mitosis with an extranuclear spindle that traverses the nucleus in cytoplasmic grooves or tunnels is viewed as one of the morphological features shared by syndinean and core dinoflagellates. Here we describe nuclear morphology and mitosis in the syndinean dinoflagellate Amoebophrya sp. from Akashiwo sanguinea, a member of the A. ceratii complex, as revealed by protargol silver impregnation, DNA specific fluorochromes, and transmission electron microscopy. Our observations show that not all species classified as dinoflagellates have an extranuclear spindle. In Amoebophrya sp. from A. sanguinea, an extranuclear microtubule cylinder located in a depression in the nuclear surface during interphase moves into the nucleoplasm via sequential membrane fusion events and develops into an entirely intranuclear spindle. Results suggest that the intranuclear spindle of Amoebophrya spp. may have evolved from an ancestral extranuclear spindle and indicate the need for taxonomic revision of the Amoebophryidae. Copyright © 2015 Elsevier GmbH. All rights reserved.

Open-jaw syndrome in chinook salmon (Oncorhynchus tshawytscha) at a hatchery

USGS Publications Warehouse

Crouch, Dennis E.; Yasutake, William T.; Rucker, Robert R.

1973-01-01

Nearly 0.5% of the yearling spring chinook salmon (Oncorhynchus tshawytscha) at a national fish hatchery were observed with mouth agape, the condition occurring in two of 16 ponds. X-radiographs and histological preparations indicated that the articular bone of the lower jaw was malformed and dislocated dorsal and posterior to its normal point of attachment. The bone appeared to be embedded in the mandibular muscle and surrounded by an extensive fibrous tissue network. Genetic aberration, environmental interaction, and teratogenic substances are discussed as possible causes of the anomaly.

Spatial signals link exit from mitosis to spindle position.

PubMed

Falk, Jill Elaine; Tsuchiya, Dai; Verdaasdonk, Jolien; Lacefield, Soni; Bloom, Kerry; Amon, Angelika

2016-05-11

In budding yeast, if the spindle becomes mispositioned, cells prevent exit from mitosis by inhibiting the mitotic exit network (MEN). The MEN is a signaling cascade that localizes to spindle pole bodies (SPBs) and activates the phosphatase Cdc14. There are two competing models that explain MEN regulation by spindle position. In the 'zone model', exit from mitosis occurs when a MEN-bearing SPB enters the bud. The 'cMT-bud neck model' posits that cytoplasmic microtubule (cMT)-bud neck interactions prevent MEN activity. Here we find that 1) eliminating cMT- bud neck interactions does not trigger exit from mitosis and 2) loss of these interactions does not precede Cdc14 activation. Furthermore, using binucleate cells, we show that exit from mitosis occurs when one SPB enters the bud despite the presence of a mispositioned spindle. We conclude that exit from mitosis is triggered by a correctly positioned spindle rather than inhibited by improper spindle position.

O-Linked N-Acetylglucosamine Cycling Regulates Mitotic Spindle Organization*

PubMed Central

Tan, Ee Phie; Caro, Sarah; Potnis, Anish; Lanza, Christopher; Slawson, Chad

2013-01-01

Any defects in the correct formation of the mitotic spindle will lead to chromosomal segregation errors, mitotic arrest, or aneuploidy. We demonstrate that O-linked N-acetylglucosamine (O-GlcNAc), a post-translational modification of serine and threonine residues in nuclear and cytoplasmic proteins, regulates spindle function. In O-GlcNAc transferase or O-GlcNAcase gain of function cells, the mitotic spindle is incorrectly assembled. Chromosome condensation and centrosome assembly is impaired in these cells. The disruption in spindle architecture is due to a reduction in histone H3 phosphorylation by Aurora kinase B. However, gain of function cells treated with the O-GlcNAcase inhibitor Thiamet-G restored the assembly of the spindle and partially rescued histone phosphorylation. Together, these data suggest that the coordinated addition and removal of O-GlcNAc, termed O-GlcNAc cycling, regulates mitotic spindle organization and provides a potential new perspective on how O-GlcNAc regulates cellular events. PMID:23946484

Human Nek7-interactor RGS2 is required for mitotic spindle organization

PubMed Central

de Souza, Edmarcia Elisa; Hehnly, Heidi; Perez, Arina Marina; Meirelles, Gabriela Vaz; Smetana, Juliana Helena Costa; Doxsey, Stephen; Kobarg, Jörg

2015-01-01

The mitotic spindle apparatus is composed of microtubule (MT) networks attached to kinetochores organized from 2 centrosomes (a.k.a. spindle poles). In addition to this central spindle apparatus, astral MTs assemble at the mitotic spindle pole and attach to the cell cortex to ensure appropriate spindle orientation. We propose that cell cycle-related kinase, Nek7, and its novel interacting protein RGS2, are involved in mitosis regulation and spindle formation. We found that RGS2 localizes to the mitotic spindle in a Nek7-dependent manner, and along with Nek7 contributes to spindle morphology and mitotic spindle pole integrity. RGS2-depletion leads to a mitotic-delay and severe defects in the chromosomes alignment and congression. Importantly, RGS2 or Nek7 depletion or even overexpression of wild-type or kinase-dead Nek7, reduced γ-tubulin from the mitotic spindle poles. In addition to causing a mitotic delay, RGS2 depletion induced mitotic spindle misorientation coinciding with astral MT-reduction. We propose that these phenotypes directly contribute to a failure in mitotic spindle alignment to the substratum. In conclusion, we suggest a molecular mechanism whereupon Nek7 and RGS2 may act cooperatively to ensure proper mitotic spindle organization. PMID:25664600

Human Nek7-interactor RGS2 is required for mitotic spindle organization.

PubMed

de Souza, Edmarcia Elisa; Hehnly, Heidi; Perez, Arina Marina; Meirelles, Gabriela Vaz; Smetana, Juliana Helena Costa; Doxsey, Stephen; Kobarg, Jörg

2015-01-01

The mitotic spindle apparatus is composed of microtubule (MT) networks attached to kinetochores organized from 2 centrosomes (a.k.a. spindle poles). In addition to this central spindle apparatus, astral MTs assemble at the mitotic spindle pole and attach to the cell cortex to ensure appropriate spindle orientation. We propose that cell cycle-related kinase, Nek7, and its novel interacting protein RGS2, are involved in mitosis regulation and spindle formation. We found that RGS2 localizes to the mitotic spindle in a Nek7-dependent manner, and along with Nek7 contributes to spindle morphology and mitotic spindle pole integrity. RGS2-depletion leads to a mitotic-delay and severe defects in the chromosomes alignment and congression. Importantly, RGS2 or Nek7 depletion or even overexpression of wild-type or kinase-dead Nek7, reduced γ-tubulin from the mitotic spindle poles. In addition to causing a mitotic delay, RGS2 depletion induced mitotic spindle misorientation coinciding with astral MT-reduction. We propose that these phenotypes directly contribute to a failure in mitotic spindle alignment to the substratum. In conclusion, we suggest a molecular mechanism whereupon Nek7 and RGS2 may act cooperatively to ensure proper mitotic spindle organization.

Self-organization mechanisms in the assembly and maintenance of bipolar spindles

NASA Astrophysics Data System (ADS)

Burbank, Kendra Stewart

Anastral, meiotic spindles are thought to be organized differently from astral, mitotic spindles, but the field has lacked basic structural information required to describe and model them, including the location of microtubule nucleating sites and minus ends. How the various components of spindles act together to establish and maintain the dynamic bipolar structure of spindles is not understood. We measure the distributions of oriented microtubules (MTs) in metaphase anastral spindles in Xenopus extracts by fluorescence speckle microscopy and cross-correlation analysis. We localized plus ends by tubulin incorporation and combined this with the orientation data to infer the localization of minus ends. We find that minus ends are localized throughout the spindle, sparsely at the equator and at higher concentrations near the poles. This dads to the surprising conclusion that spindles contained many short MTs, not connected to the spindle poles. Based on these data, we propose a slide-and-cluster model based on four known molecular activities: MT nucleation near chromosomes, the sliding of MTs by a plus-enddirected motor, the clustering of their minus ends by a minus-end-directed motor, and the loss of MTs by dynamic instability. This work demonstrates how the interplay between two types of motors together with continual nucleation of MTs by chromosomes could organize the MTs into spindles. Our model applies to overlapping, nonkinetochore MTs in anastral spindles, and perhaps also to interpolar MTs in astral spindles. We show mathematically that the slide-and-cluster mechanism robustly forms bipolar spindles a stable steady-state length, sometimes with sharp poles. This model accounts for several experimental observations that were difficult to explain with existing models, and is the first self contained model for anastral spindle assembly, MT sliding (known as poleward flux), and spindle bistability. Our experimental results support the slide-and-cluster scenario

Physical Limits on the Precision of Mitotic Spindle Positioning by Microtubule Pushing forces: Mechanics of mitotic spindle positioning.

PubMed

Howard, Jonathon; Garzon-Coral, Carlos

2017-11-01

Tissues are shaped and patterned by mechanical and chemical processes. A key mechanical process is the positioning of the mitotic spindle, which determines the size and location of the daughter cells within the tissue. Recent force and position-fluctuation measurements indicate that pushing forces, mediated by the polymerization of astral microtubules against- the cell cortex, maintain the mitotic spindle at the cell center in Caenorhabditis elegans embryos. The magnitude of the centering forces suggests that the physical limit on the accuracy and precision of this centering mechanism is determined by the number of pushing microtubules rather than by thermally driven fluctuations. In cells that divide asymmetrically, anti-centering, pulling forces generated by cortically located dyneins, in conjunction with microtubule depolymerization, oppose the pushing forces to drive spindle displacements away from the center. Thus, a balance of centering pushing forces and anti-centering pulling forces localize the mitotic spindles within dividing C. elegans cells. © 2017 The Authors. BioEssays published by Wiley Periodicals, Inc.

Edge orientation signals in tactile afferents of macaques

PubMed Central

Suresh, Aneesha K.

2016-01-01

The orientation of edges indented into the skin has been shown to be encoded in the responses of neurons in primary somatosensory cortex in a manner that draws remarkable analogies to their counterparts in primary visual cortex. According to the classical view, orientation tuning arises from the integration of untuned input from thalamic neurons with aligned but spatially displaced receptive fields (RFs). In a recent microneurography study with human subjects, the precise temporal structure of the responses of individual mechanoreceptive afferents to scanned edges was found to carry information about their orientation. This putative mechanism could in principle contribute to or complement the classical rate-based code for orientation. In the present study, we further examine orientation information carried by mechanoreceptive afferents of Rhesus monkeys. To this end, we record the activity evoked in cutaneous mechanoreceptive afferents when edges are indented into or scanned across the skin. First, we confirm that information about the edge orientation can be extracted from the temporal patterning in afferent responses of monkeys, as is the case in humans. Second, we find that while the coarse temporal profile of the response can be predicted linearly from the layout of the RF, the fine temporal profile cannot. Finally, we show that orientation signals in tactile afferents are often highly dependent on stimulus features other than orientation, which complicates putative decoding strategies. We discuss the challenges associated with establishing a neural code at the somatosensory periphery, where afferents are exquisitely sensitive and nearly deterministic. PMID:27655968

Reciprocal inhibition between motor neurons of the tibialis anterior and triceps surae in humans.

PubMed

Yavuz, Utku Ş; Negro, Francesco; Diedrichs, Robin; Farina, Dario

2018-05-01

Motor neurons innervating antagonist muscles receive reciprocal inhibitory afferent inputs to facilitate the joint movement in the two directions. The present study investigates the mutual transmission of reciprocal inhibitory afferent inputs between the tibialis anterior (TA) and triceps surae (soleus and medial gastrocnemius) motor units. We assessed this mutual mechanism in large populations of motor units for building a statistical distribution of the inhibition amplitudes during standardized input to the motor neuron pools to minimize the effect of modulatory pathways. Single motor unit activities were identified using high-density surface electromyography (HDsEMG) recorded from the TA, soleus (Sol), and medial gastrocnemius (GM) muscles during isometric dorsi- and plantarflexion. Reciprocal inhibition on the antagonist muscle was elicited by electrical stimulation of the tibial (TN) or common peroneal nerves (CPN). The probability density distributions of reflex strength for each muscle were estimated to examine the strength of mutual transmission of reciprocal inhibitory input. The results showed that the strength of reciprocal inhibition in the TA motor units was fourfold greater than for the GM and the Sol motor units. This suggests an asymmetric transmission of reciprocal inhibition between ankle extensor and flexor muscles. This asymmetry cannot be explained by differences in motor unit type composition between the investigated muscles since we sampled low-threshold motor units in all cases. Therefore, the differences observed for the strength of inhibition are presumably due to a differential reciprocal spindle afferent input and the relative contribution of nonreciprocal inhibitory pathways. NEW & NOTEWORTHY We investigated the mutual transmission of reciprocal inhibition in large samples of motor units using a standardized input (electrical stimulation) to the motor neurons. The results demonstrated that the disynaptic reciprocal inhibition exerted

Spatial signals link exit from mitosis to spindle position

PubMed Central

Falk, Jill Elaine; Tsuchiya, Dai; Verdaasdonk, Jolien; Lacefield, Soni; Bloom, Kerry; Amon, Angelika

2016-01-01

In budding yeast, if the spindle becomes mispositioned, cells prevent exit from mitosis by inhibiting the mitotic exit network (MEN). The MEN is a signaling cascade that localizes to spindle pole bodies (SPBs) and activates the phosphatase Cdc14. There are two competing models that explain MEN regulation by spindle position. In the 'zone model', exit from mitosis occurs when a MEN-bearing SPB enters the bud. The 'cMT-bud neck model' posits that cytoplasmic microtubule (cMT)-bud neck interactions prevent MEN activity. Here we find that 1) eliminating cMT– bud neck interactions does not trigger exit from mitosis and 2) loss of these interactions does not precede Cdc14 activation. Furthermore, using binucleate cells, we show that exit from mitosis occurs when one SPB enters the bud despite the presence of a mispositioned spindle. We conclude that exit from mitosis is triggered by a correctly positioned spindle rather than inhibited by improper spindle position. DOI: http://dx.doi.org/10.7554/eLife.14036.001 PMID:27166637

Sleep spindle activity and cognitive performance in healthy children.

PubMed

Chatburn, Alex; Coussens, Scott; Lushington, Kurt; Kennedy, Declan; Baumert, Mathias; Kohler, Mark

2013-02-01

To investigate the association between indices of sleep spindle activity and cognitive performance in a sample of healthy children. Correlational. Intelligence (Stanford-Binet) and neurocognitive functioning (NEPSY) were assessed, with sleep variables being measured during overnight polysomnography. Hospital sleep laboratory. Twenty-seven healthy children (mean age 8.19 y; 14 female, 13 male). N/A. Participants underwent a single night of overnight polysomnography after completing measures of intelligence and neurocognitive functioning. Sleep spindles were visually identified by an experienced sleep scoring technician and separated algorithmically into fast (> 13 Hz) and slow spindle (< 13 Hz) categories. The number of fast spindles was significantly correlated with narrative memory (r(s) = 0.38) and sensorimotor functioning (-0.43). Mean central frequency of spindles was also significantly correlated with sensorimotor functioning (-0.41), planning ability (-0.41), and working memory (-0.54). Basal sleep spindle activity is associated with different aspects of cognitive performance in children. To the extent that these associations in a pediatric population are different from what is known in adult sleep may play an important role in development.

Measurement of Spindle Rigidity by using a Magnet Loader

NASA Astrophysics Data System (ADS)

Yamazaki, Taku; Matsubara, Atsushi; Fujita, Tomoya; Muraki, Toshiyuki; Asano, Kohei; Kawashima, Kazuyuki

The static rigidity of a rotating spindle in the radial direction is investigated in this research. A magnetic loading device (magnet loader) has been developed for the measurement. The magnet loader, which has coils and iron cores, generates the electromagnetic force and attracts a dummy tool attached to the spindle. However, the eddy current is generated in the dummy tool with the spindle rotation and reduces the attractive force at high spindle speed. In order to understand the magnetic flux and eddy current in the dummy tool, the electromagnetic field analysis by FEM was carried out. Grooves on the attraction surface of the dummy tool were designed to cut the eddy current flow. The dimension of the groove were decided based on the FEM analysis, and the designed tool were manufactured and tested. The test result shows that the designed tool successfully reduces the eddy current and recovers the attractive force. By using the magnet loader and the grooved tool, the spindle rigidity can be measured when the spindle rotates with a speed up to 10,000 min-1.

Intramuscular temperature modulates glutamate-evoked masseter muscle pain intensity in humans.

PubMed

Sato, Hitoshi; Castrillon, Eduardo E; Cairns, Brian E; Bendixen, Karina H; Wang, Kelun; Nakagawa, Taneaki; Wajima, Koichi; Svensson, Peter

2015-01-01

To determine whether glutamate-evoked jaw muscle pain is altered by the temperature of the solution injected. Sixteen healthy volunteers participated and received injections of hot (48°C), neutral (36°C), or cold (3°C) solutions (0.5 mL) of glutamate or isotonic saline into the masseter muscle. Pain intensity was assessed with an electronic visual analog scale (eVAS). Numeric rating scale (NRS) scores of unpleasantness and temperature perception, pain-drawing areas, and pressure pain thresholds (PPTs) were also measured. Participants filled out the McGill Pain Questionnaire (MPQ). Two-way or three-way repeated measures ANOVA were used for data analyses. Injection of hot glutamate and cold glutamate solutions significantly increased and decreased, respectively, the peak pain intensity compared with injection of neutral glutamate solution. The duration of glutamate-evoked pain was significantly longer when hot glutamate was injected than when cold glutamate was injected. No significant effect of temperature on pain intensity was observed when isotonic saline was injected. No effect of solution temperature was detected on unpleasantness, heat perception, cold perception, area of pain drawings, or PPTs. There was a significantly greater use of the "numb" term in the MPQ to describe the injection of cold solutions compared to the injection of both neutral and hot solutions. Glutamate-evoked jaw muscle pain was significantly altered by the temperature of the injection solution. Although temperature perception in the jaw muscle is poor, pain intensity is increased when the muscle tissue temperature is elevated.

Mechanisms of reflex bladder activation by pudendal afferents

PubMed Central

Woock, John P.; Yoo, Paul B.

2011-01-01

Activation of pudendal afferents can evoke bladder contraction or relaxation dependent on the frequency of stimulation, but the mechanisms of reflex bladder excitation evoked by pudendal afferent stimulation are unknown. The objective of this study was to determine the contributions of sympathetic and parasympathetic mechanisms to bladder contractions evoked by stimulation of the dorsal nerve of the penis (DNP) in α-chloralose anesthetized adult male cats. Bladder contractions were evoked by DNP stimulation only above a bladder volume threshold equal to 73 ± 12% of the distension-evoked reflex contraction volume threshold. Bilateral hypogastric nerve transection (to eliminate sympathetic innervation of the bladder) or administration of propranolol (a β-adrenergic antagonist) decreased the stimulation-evoked and distension-evoked volume thresholds by −25% to −39%. Neither hypogastric nerve transection nor propranolol affected contraction magnitude, and robust bladder contractions were still evoked by stimulation at volume thresholds below the distension-evoked volume threshold. As well, inhibition of distention-evoked reflex bladder contractions by 10 Hz stimulation of the DNP was preserved following bilateral hypogastric nerve transection. Administration of phentolamine (an α-adrenergic antagonist) increased stimulation-evoked and distension-evoked volume thresholds by 18%, but again, robust contractions were still evoked by stimulation at volumes below the distension-evoked threshold. These results indicate that sympathetic mechanisms contribute to establishing the volume dependence of reflex contractions but are not critical to the excitatory pudendal to bladder reflex. A strong correlation between the magnitude of stimulation-evoked bladder contractions and bladder volume supports that convergence of pelvic afferents and pudendal afferents is responsible for bladder excitation evoked by pudendal afferents. Further, abolition of stimulation-evoked bladder

The fusimotor and reafferent origin of the sense of force and weight

PubMed Central

Luu, Billy L; Day, Brian L; Cole, Jonathan D; Fitzpatrick, Richard C

2011-01-01

Abstract Signals associated with the command the brain sends to muscles are thought to create the sensation of heaviness when we lift an object. Thus, as a muscle is weakened by fatigue or partial paralysis (neuromuscular blockade), the increase in the motor command needed to lift a weight is thought to explain the increasing subjective heaviness of the lifted object. With different fatiguing contractions we approximately halved the force output of the thumb flexor muscles, which were then used to lift an object. For two deafferented subjects the perceived heaviness of the lifted object approximately doubled, in keeping with the central-signal theory. However, for normal subjects this resulted in objects feeling the same or lighter, inconsistent with the central-signal theory but consistent with the expected effects of the conditioning contractions on the sensitivity of peripheral receptors. In separate experiments we subjected the forearm muscles to complete paralysis with a non-depolarising neuromuscular blocking agent and then allowed them to recover to approximately half-force output. This also resulted in objects feeling lighter when lifted by the semi-paralysed thumb, even though the motor command to the motoneurons must have been greater. This is readily explained by reduced lift-related reafference caused by the prolonged paralysis of muscle spindle intrafusal fibres. We conclude that peripheral signals, including a major contribution from muscle spindles, normally give rise to the sense of exerted force. In concept, however, reafference from peripheral receptors may also be considered a centrally generated signal that traverses efferent and then afferent pathways to feed perceptual centres rather than one confined entirely to the central nervous system. These results therefore challenge the distinction between central- and peripheral-based perception, and the concept that muscle spindles provide only information about limb position and movement. PMID

The crack effect on instability in a machine tool spindle with gas bearings

NASA Astrophysics Data System (ADS)

Huang, Bo-Wun

2005-09-01

Gas-bearing spindles are required for increased spindle speed in precise machining. Due to manufacturing flaws or cyclic loading, cracks frequently appear in a rotating spindle systems. Cracks markedly affect the dynamic characteristics of rotating machinery. Hence, in this study, high-speed spindles with gas bearings and the crack effect on the instability dynamics are considered. Most investigations on dynamic characteristics of the spindle system were confined to ball-bearing-type spindles. This work examines the dynamic instability in a cracked rotating spindle system with gas bearings. A round Euler-Bernoulli beam is used to approximate the spindle. The Hamilton principle is applied to derive the equation of motion for the spindle system. The effects of crack depth, rotation speed and provided air pressure on the dynamic instability of a rotating spindle system are studied

Fetal myosin immunoreactivity in human dystrophic muscle.

PubMed

Schiaffino, S; Gorza, L; Dones, I; Cornelio, F; Sartore, S

1986-01-01

We report immunofluorescence observations on normal and dystrophic human muscle using an antibody (anti-bF) raised against bovine fetal myosin and specific for fetal myosin heavy chains. In rat skeletal muscle, anti-bF was previously found to react selectively with myosin isoforms expressed during fetal and early postnatal development and in regenerating muscles. Anti-bF stained most fibers in human fetal and neonatal muscle, whereas only nuclear chain fibers of muscle spindles were labeled in normal adult muscle. In muscle biopsies from patients with Duchenne's muscular dystrophy, numerous extrafusal fibers were stained: some were small regenerating fibers, others were larger fibers presumably resulting from previous regenerative events. Fetal myosin immunoreactivity in Duchenne's dystrophy appears to reflect the reexpression of fetal-specific myosin isoforms and provides a new valuable tool for identifying regenerating fibers and following their destiny in dystrophic muscle.

Physical determinants of bipolar mitotic spindle assembly and stability in fission yeast

PubMed Central

Blackwell, Robert; Edelmaier, Christopher; Sweezy-Schindler, Oliver; Lamson, Adam; Gergely, Zachary R.; O’Toole, Eileen; Crapo, Ammon; Hough, Loren E.; McIntosh, J. Richard; Glaser, Matthew A.; Betterton, Meredith D.

2017-01-01

Mitotic spindles use an elegant bipolar architecture to segregate duplicated chromosomes with high fidelity. Bipolar spindles form from a monopolar initial condition; this is the most fundamental construction problem that the spindle must solve. Microtubules, motors, and cross-linkers are important for bipolarity, but the mechanisms necessary and sufficient for spindle assembly remain unknown. We describe a physical model that exhibits de novo bipolar spindle formation. We began with physical properties of fission-yeast spindle pole body size and microtubule number, kinesin-5 motors, kinesin-14 motors, and passive cross-linkers. Our model results agree quantitatively with our experiments in fission yeast, thereby establishing a minimal system with which to interrogate collective self-assembly. By varying the features of our model, we identify a set of functions essential for the generation and stability of spindle bipolarity. When kinesin-5 motors are present, their bidirectionality is essential, but spindles can form in the presence of passive cross-linkers alone. We also identify characteristic failed states of spindle assembly—the persistent monopole, X spindle, separated asters, and short spindle, which are avoided by the creation and maintenance of antiparallel microtubule overlaps. Our model can guide the identification of new, multifaceted strategies to induce mitotic catastrophes; these would constitute novel strategies for cancer chemotherapy. PMID:28116355

Spinal spindle cell haemangioma: an atypical location.

PubMed

Talan-Hranilović, J; Vucić, M; Sajko, T; Bedek, D; Tomić, K; Lupret, V

2007-03-01

We present a case of the 31-year-old male patient who complained of weakness in both legs and progressed slowly. Neuroimagine of the thoracic spine showed an intraspinal, extradural mass lesion, measuring 5.3 x 1.2 cm at the Th1-Th3 level. Histologically the lesion was a spindle cell haemangioma composed of dilated vascular spaces and a proliferation of bland appearing interspersed spindle cells. Immunohistochemical analysis was diffusely positive for VIM, SMA and focally for CD34. This lesion is uncommon and shows a predilection for distal extremities. Spindle cell haemangioma within the spine has not been previously reported in the literature.

Neurochemical diversity of afferent neurons that transduce sensory signals from dog ventricular myocardium

PubMed Central

Hoover, Donald B.; Shepherd, Angela V.; Southerland, E. Marie; Armour, J. Andrew; Ardell, Jeffrey L.

2008-01-01

While much is known about the influence of ventricular afferent neurons on cardiovascular function in the dog, identification of the neurochemicals transmitting cardiac afferent signals to central neurons is lacking. Accordingly, we identified ventricular afferent neurons in canine dorsal root ganglia (DRG) and nodose ganglia by retrograde labeling after injecting horseradish peroxidase (HRP) into the anterior right and left ventricles. Primary antibodies from three host species were used in immunohistochemical experiments to simultaneously evaluate afferent somata for the presence of HRP and markers for two neurotransmitters. Only a small percentage (2%) of afferent somata were labeled with HRP. About half of the HRP-identified ventricular afferent neurons in T3 DRG also stained for substance P (SP), calcitonin gene-related peptide (CGRP), or neuronal nitric oxide synthase (nNOS), either alone or with two markers colocalized. Ventricular afferent neurons and the general population of T3 DRG neurons showed the same labeling profiles; CGRP (alone or colocalized with SP) being the most common (30–40% of ventricular afferent somata in T3 DRG). About 30% of the ventricular afferent neurons in T2 DRG displayed CGRP immunoreactivity and binding of the putative nociceptive marker IB4. Ventricular afferent neurons of the nodose ganglia were distinct from those in the DRG by having smaller size and lacking immunoreactivity for SP, CGRP, and nNOS. These findings suggest that ventricular sensory information is transferred to the central nervous system by relatively small populations of vagal and spinal afferent neurons and that spinal afferents use a variety of neurotransmitters. PMID:18558516

Neurochemical diversity of afferent neurons that transduce sensory signals from dog ventricular myocardium.

PubMed

Hoover, Donald B; Shepherd, Angela V; Southerland, E Marie; Armour, J Andrew; Ardell, Jeffrey L

2008-08-18

While much is known about the influence of ventricular afferent neurons on cardiovascular function in the dog, identification of the neurochemicals transmitting cardiac afferent signals to central neurons is lacking. Accordingly, we identified ventricular afferent neurons in canine dorsal root ganglia (DRG) and nodose ganglia by retrograde labeling after injecting horseradish peroxidase (HRP) into the anterior right and left ventricles. Primary antibodies from three host species were used in immunohistochemical experiments to simultaneously evaluate afferent somata for the presence of HRP and markers for two neurotransmitters. Only a small percentage (2%) of afferent somata were labeled with HRP. About half of the HRP-identified ventricular afferent neurons in T(3) DRG also stained for substance P (SP), calcitonin gene-related peptide (CGRP), or neuronal nitric oxide synthase (nNOS), either alone or with two markers colocalized. Ventricular afferent neurons and the general population of T(3) DRG neurons showed the same labeling profiles; CGRP (alone or colocalized with SP) being the most common (30-40% of ventricular afferent somata in T(3) DRG). About 30% of the ventricular afferent neurons in T(2) DRG displayed CGRP immunoreactivity and binding of the putative nociceptive marker IB(4). Ventricular afferent neurons of the nodose ganglia were distinct from those in the DRG by having smaller size and lacking immunoreactivity for SP, CGRP, and nNOS. These findings suggest that ventricular sensory information is transferred to the central nervous system by relatively small populations of vagal and spinal afferent neurons and that spinal afferents use a variety of neurotransmitters.

Assessing EEG sleep spindle propagation. Part 1: theory and proposed methodology.

PubMed

O'Reilly, Christian; Nielsen, Tore

2014-01-15

A convergence of studies has revealed sleep spindles to be associated with sleep-related cognitive processing and even with fundamental waking state capacities such as intelligence. However, some spindle characteristics, such as propagation direction and delay, may play a decisive role but are only infrequently investigated because of technical complexities. A new methodology for assessing sleep spindle propagation over the human scalp using noninvasive electroencephalography (EEG) is described. This approach is based on the alignment of time-frequency representations of spindle activity across recording channels. This first of a two-part series concentrates on framing theoretical considerations related to EEG spindle propagation and on detailing the methodology. A short example application is provided that illustrates the repeatability of results obtained with the new propagation measure in a sample of 32 night recordings. A more comprehensive experimental investigation is presented in part two of the series. Compared to existing methods, this approach is particularly well adapted for studying the propagation of sleep spindles because it estimates time delays rather than phase synchrony and it computes propagation properties for every individual spindle with windows adjusted to the specific spindle duration. The proposed methodology is effective in tracking the propagation of spindles across the scalp and may thus help in elucidating the temporal aspects of sleep spindle dynamics, as well as other transient EEG and MEG events. A software implementation (the Spyndle Python package) is provided as open source software. Copyright © 2013 Elsevier B.V. All rights reserved.

Dual mechanism controls asymmetric spindle position in ascidian germ cell precursors.

PubMed

Prodon, François; Chenevert, Janet; Hébras, Céline; Dumollard, Rémi; Faure, Emmanuel; Gonzalez-Garcia, Jose; Nishida, Hiroki; Sardet, Christian; McDougall, Alex

2010-06-01

Mitotic spindle orientation with respect to cortical polarity cues generates molecularly distinct daughter cells during asymmetric cell division (ACD). However, during ACD it remains unknown how the orientation of the mitotic spindle is regulated by cortical polarity cues until furrowing begins. In ascidians, the cortical centrosome-attracting body (CAB) generates three successive unequal cleavages and the asymmetric segregation of 40 localized postplasmic/PEM RNAs in germ cell precursors from the 8-64 cell stage. By combining fast 4D confocal fluorescence imaging with gene-silencing and classical blastomere isolation experiments, we show that spindle repositioning mechanisms are active from prometaphase until anaphase, when furrowing is initiated in B5.2 cells. We show that the vegetal-most spindle pole/centrosome is attracted towards the CAB during prometaphase, causing the spindle to position asymmetrically near the cortex. Next, during anaphase, the opposite spindle pole/centrosome is attracted towards the border with neighbouring B5.1 blastomeres, causing the spindle to rotate (10 degrees /minute) and migrate (3 microm/minute). Dynamic 4D fluorescence imaging of filamentous actin and plasma membrane shows that precise orientation of the cleavage furrow is determined by this second phase of rotational spindle displacement. Furthermore, in pairs of isolated B5.2 blastomeres, the second phase of rotational spindle displacement was lost. Finally, knockdown of PEM1, a protein localized in the CAB and required for unequal cleavage in B5.2 cells, completely randomizes spindle orientation. Together these data show that two separate mechanisms active during mitosis are responsible for spindle positioning, leading to precise orientation of the cleavage furrow during ACD in the cells that give rise to the germ lineage in ascidians.

Sleep spindles and intelligence in early childhood-developmental and trait-dependent aspects.

PubMed

Ujma, Péter P; Sándor, Piroska; Szakadát, Sára; Gombos, Ferenc; Bódizs, Róbert

2016-12-01

Sleep spindles act as a powerful marker of individual differences in cognitive ability. Sleep spindle parameters correlate with both age-related changes in cognitive abilities and with the age-independent concept of IQ. While some studies have specifically demonstrated the relationship between sleep spindles and intelligence in young children, our previous work in older subjects revealed sex differences in the sleep spindle correlates of IQ, which was never investigated in small children before. We investigated the relationship between age, Raven Colored Progressive Matrices (CPM) scores and sleep spindles in 28 young children (age 4-8 years, 15 girls). We specifically investigated sex differences in the psychometric correlates of sleep spindles. We also aimed to separate the correlates of sleep spindles that are because of age-related maturation from other effects that reflect an age-independent relationship between sleep spindles and general intelligence. Our results revealed a modest positive correlation between fast spindle amplitude and age. Raven CPM scores positively correlated with both slow and fast spindle amplitude, but this effect remained a tendency in males and vanished after correcting for the effects of age. Age-corrected correlations between Raven CPM scores and both slow and fast spindle amplitude were only significant in females. Overall, our results show that in male children sleep spindles are a maturational marker, but in female children they indicate trait-like intelligence, in line with previous studies in adolescent and adult subjects. Thalamocortical white matter connectivity may be the underlying mechanism behind both higher spindle amplitude and higher intelligence in female, but not male subjects. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

HDAC8 functions in spindle assembly during mouse oocyte meiosis

PubMed Central

Shu, Jing; Chen, Xueqin; Shi, Yingjiao; Wang, Ensheng; Wang, Li; Hu, Qinbo; Dai, Yibo; Xiong, Bo

2017-01-01

HDAC8 is a class I histone deacetylase that functions in a variety of biological processes through its non-histone substrates. However, its roles during oocyte meiosis remain elusive. Here, we document that HDAC8 localizes at spindle poles and positively participates in the regulation of microtubule organization and spindle assembly in mouse oocytes. Depletion of HDAC8 by siRNA-based gene silencing results in various spindle defects and chromosome misalignment during oocyte meiotic maturation, accompanied by impaired kinetochore-microtubule attachments. Consequently, a higher incidence of aneuploidy is generated in HDAC8-depleted MII eggs. In addition, inhibition of HDAC8 activity with its selective inhibitor PCI-34051 phenocopies the spindle/chromosome defects resulting from HDAC8 depletion by siRNA injection. Finally, we find that HDAC8 is required for the correct localization of ϕ-tubulin to spindle poles. Collectively, these data reveal that HDAC8 plays a significant role in regulating spindle assembly and thus ensuring the euploidy in mouse eggs. PMID:28223544

The Effect of Varying Biting Position on Relative Jaw Muscle EMG activity

DTIC Science & Technology

1988-09-01

with muscle force is the key to 13 this approach as it allows inference of muscle contraction activity from EMG data. This relationship has been the...5! 15 LITERATURE REVIEW Introduction: The study of the physiology of bite force, muscle contraction force, joint reaction force and the lever system...Currently, the best method of indirectly observing muscle contraction activity is through electromyography. Although there appears to be a time delay

Hair cell tufts and afferent innervation of the bullfrog crista ampullaris

NASA Technical Reports Server (NTRS)

Myers, Steven F.; Lewis, Edwin R.

1990-01-01

Within the bullfrog semicircular canal crista, hair cell tuft types were defined and mapped with the aid of scanning electron microscopy. Dye-filled planar afferent axons had mean distal axonal diameters of 1.6-4.9 microns, highly branched arbors, and contacted 11-24 hair cells. Dye-filled isthmus afferent axons had mean distal axonal diameters of 1.8-7.9 microns, with either small or large field arbors contacting 4-9 or 25-31 hair cells. The estimated mean number of contacts per innervated hair cell was 2.2 for planar and 1.3 for isthmus afferent neurons. Data on evoked afferent responses were available only for isthmus units that were observed to respond to our microrotational stimuli. Of 21 such afferent neurons, eight were successfully dye-filled. Within this sample, high-gain units had large field arbors and lower-gain units had small field arbors. The sensitivity of each afferent neuron was analyzed in terms of noise equivalent input (NEI), the stimulus amplitude for which the afferent response amplitude is just equivalent to the rms deviation of the instantaneous spike rate. NEI for isthmus units varied from 0.63 to 8.2 deg/s; the mean was 3.2 deg/s.

Differential localization of vesicular glutamate transporters and peptides in corneal afferents to trigeminal nucleus caudalis.

PubMed

Hegarty, Deborah M; Tonsfeldt, Karen; Hermes, Sam M; Helfand, Helen; Aicher, Sue A

2010-09-01

Trigeminal afferents convey nociceptive information from the corneal surface of the eye to the trigeminal subnucleus caudalis (Vc). Trigeminal afferents, like other nociceptors, are thought to use glutamate and neuropeptides as neurotransmitters. The current studies examined whether corneal afferents contain both neuropeptides and vesicular glutamate transporters. Corneal afferents to the Vc were identified by using cholera toxin B (CTb). Corneal afferents project in two clusters to the rostral and caudal borders of the Vc, regions that contain functionally distinct nociceptive neurons. Thus, corneal afferents projecting to these two regions were examined separately. Dual immunocytochemical studies combined CTb with either calcitonin gene-related peptide (CGRP), substance P (SP), vesicular glutamate transporter 1 (VGluT1), or VGluT2. Corneal afferents were more likely to contain CGRP than SP, and corneal afferents projecting to the rostral region were more likely to contain CGRP than afferents projecting caudally. Overall, corneal afferents were equally likely to contain VGluT1 or VGluT2. Together, 61% of corneal afferents contained either VGluT1 or VGluT2, suggesting that some afferents lack a VGluT. Caudal corneal afferents were more likely to contain VGluT2 than VGluT1, whereas rostral corneal afferents were more likely to contain VGluT1 than VGluT2. Triple-labeling studies combining CTb, CGRP, and VGluT2 showed that very few corneal afferents contain both CGRP and VGluT2, caudally (1%) and rostrally (2%). These results suggest that most corneal afferents contain a peptide or a VGluT, but rarely both. Our results are consistent with a growing literature suggesting that glutamatergic and peptidergic sensory afferents may be distinct populations.

Bruxism: Is There an Indication for Muscle-Stretching Exercises?

PubMed

Gouw, Simone; de Wijer, Anton; Creugers, Nico Hj; Kalaykova, Stanimira I

Bruxism is a common phenomenon involving repetitive activation of the masticatory muscles. Muscle-stretching exercises are a recommended part of several international guidelines for musculoskeletal disorders and may be effective in management of the jaw muscle activity that gives rise to bruxism. However, most studies of muscle-stretching exercises have mainly focused on their influence on performance (eg, range of motion, coordination, and muscle strength) of the limb or trunk muscles of healthy individuals or individuals with sports-related injuries. Very few have investigated stretching of the human masticatory muscles and none muscle-stretching exercises in the management of (sleep) bruxism. This article reviews the literature on muscle-stretching exercises and their potential role in the management of sleep bruxism or its consequences in the musculoskeletal system.

Appraisal of jaw swellings in a Nigerian tertiary healthcare facility.

PubMed

Lasisi, Taye J; Adisa, Akinyele O; Olusanya, Adeola A

2013-02-01

The mandible and maxilla can be the site of myriads of lesions that may be categorized as neoplastic, cystic, reactive and infective or inflammatory. Literature reviewing jaw swellings in an amalgamated fashion are uncommon, probably because aetiologies for these swellings are varied. However, to appreciate their relative relationship, it is essential to evaluate the clinico-pathologic profile of jaw swellings. The aim of this appraisal is to describe the array of jaw swellings seen at our hospital from 1990 to 2011, to serve as a reference database. Biopsy records of all histologically diagnosed cases of jaw swellings seen at the department of Oral Pathology, University College Hospital between January 1990 and December 2011 were retrieved, coded and inputted into SPSS version 20. Data on prevalence, age, sex, site and histological diagnosis were analysed descriptively for each category of jaw swellings. All patients below 16 years were regarded as children. A total of 638 jaw swellings were recorded in the 22-year study period. The Non Odontogenic Tumours (NOT) were the commonest, accounting for 46.2% of all jaw swellings. Odontogenic Tumours (OT) formed 45% of all adult jaw swelling while it formed 25.2% in children and adolescents. Ameloblastoma was the commonest while the most common NOT was ossifying fibroma (OF). Chronic osteomyelitis of the jaws was about 6 times commoner in adult females than males and mostly involved the mandible. The most common malignant jaw swelling was Burkitts' lymphoma (BL) that was about 7 times more in children than adults. Osteogenic sarcoma was the most common malignancy in adults. Jaw swellings are extensively varied in types and pattern of occurrence. This study has categorized jaw swellings in a simple but comprehensive fashion to allow for easy referencing in local and international data acquisition and epidemiological comparison. Key words:Jaw swellings, odontogenic, Nigeria.

Jaw-phonatory coordination in chronic developmental stuttering.

PubMed

Loucks, Torrey M J; De Nil, Luc F; Sasisekaran, Jayanthi

2007-01-01

A deficiency in sensorimotor integration in a person who stutters may be a factor in the pathophysiology of developmental stuttering. To test oral sensorimotor function in adults who stutter, we used a task that requires the coordination of a jaw-opening movement with phonation onset. The task was adapted from previous limb coordination studies, which show that movement coordination depends on intact proprioception. We hypothesized that adult stutterers would show deficient jaw-phonatory coordination relative to control participants. The task required initiation of phonation as a jaw-opening movement passed through a narrow spatial target. Target amplitude and jaw movement speed were varied. The stuttering group showed significantly higher movement error and spatial variability in jaw-phonatory coordination compared to the control group, but group differences in movement velocity or duration were not found. The aberrant jaw-phonatory coordination of the stuttering participants suggests that stuttering is associated with an oral proprioceptive limitation, although, the findings are also consistent with a motor control deficit. As a result of this activity, reader will (1) learn about a hypothesis and evidence supporting the view that a sensorimotor deficit contributes to chronic developmental stuttering and (2) will obtain information about the role of proprioception in multi-articulatory coordination and how it can be tested using an oral-phonatory coordination task.

Frequent jaw-face pain in chronic Whiplash-Associated Disorders.

PubMed

Häggman-Henrikson, Birgitta; Grönqvist, Johan; Eriksson, Per-Olof

2011-01-01

Chronic Whiplash-Associated Disorders (WAD) present with frequent pain in the neck, head and shoulder regions but the presence of frequent jaw-face pain is unclear. The aim of the study was to investigate the frequency of jaw-face pain, pain in other regions, and general symptoms in chronic WAD patients. Fifty whiplash-patients and 50 healthy age- and sex-matched controls were examined by questionnaire for pain in the jaw-face, pain in other regions and other symptoms. In contrast to healthy, a majority of the WAD patients (88%) reported frequent pain in the jaw-face, in addition to frequent pain in the neck (100%), shoulders (94%), head (90%) and back (72%). The WAD patients also reported stiffness and numbness in the jaw-face region, and frequent general symptoms such as balance problems, stress and sleep disturbances. The result suggests that frequent pain in the jaw-face can be part of the spectrum of symptoms in chronic WAD.The finding of self-reported numbness in the jaw-face indicates disturbed trigeminal nerve function and merits further investigation. We conclude that assessment of WAD should include pain in the jaw-face region. A multidisciplinary rehabilitation program including dentists, preferably specialized in the area of orofacial pain, should be advocated after whiplash injury.

Physical determinants of bipolar mitotic spindle assembly and stability in fission yeast

NASA Astrophysics Data System (ADS)

Betterton, Meredith; Blackwell, Robert; Edelmaier, Christopher; Sweezy-Schindler, Oliver; Lamson, Adam; Gergely, Zachary; O'Toole, Eileen; Crapo, Ammon; Hough, Loren; McIntosh, J. Richard; Glaser, Matthew

Mitotic spindles use an elegant bipolar architecture to segregate duplicated chromosomes with high fidelity. Bipolar spindles form from a monopolar initial condition; this is the most fundamental construction problem that the spindle must solve. Microtubules, motors, and crosslinkers are important for bipolarity, but the mechanisms necessary and sufficient for spindle assembly remain unknown. Here we describe a physical model that exhibits de novo bipolar spindle formation. We began with previously published data on fission-yeast spindle-pole-body size and microtubule number, kinesin-5 motors, kinesin-14 motors, and passive crosslinkers. Our model results agree quantitatively with our experiments in fission yeast, thereby establishing a minimal system with which to interrogate collective self assembly. By varying features of our model, we identify a set of functions essential for the generation and stability of spindle bipolarity. When kinesin-5 motors are present, their bidirectionality is essential, but spindles can form in the presence of passive crosslinkers alone. We also identify characteristic failed states of spindle assembly, which are avoided by creation and maintenance of antiparallel microtubule overlaps. DMR-0847685, DMR-1551095, DMR-1420736, K25GM110486, R01GM104976, R01GM033787.

Topographical distribution of fast and slow sleep spindles in medicated depressive patients.

PubMed

Nishida, Masaki; Nakashima, Yusaku; Nishikawa, Toru

2014-10-01

To compare the properties of sleep spindles between healthy subjects and medicated patients with major depressive episode, including frequency range, spectra power, and spatial distribution of spindle power. Continuous 16-channel EEG was used to record nocturnal sleep in healthy control subjects and medicated depressive patients. Recordings were analyzed for changes in EEG power spectra and power topography. Additionally, we graphically demonstrated the pattern of spatial distribution of each type of sleep spindle, divided into fast (12.5-14 Hz) and slow spindles (11-12.5 Hz). Sleep EEG records of depressive subjects exhibited a significantly higher amplitude of slow spindles in the prefrontal region, compared with the healthy controls (P < 0.01). Fast spindles were dominant in the centroparietal region in both depressive patients and the control group. Enhanced slow spindles in the prefrontal region were observed in the medicated depressive patients and not in the healthy controls. The frequency of fast spindles in depressive patients was globally higher than that in healthy participants. The alteration in sleep spindles seen in medicated depressive subjects may reflect a pharmacological modulation of synaptic function involving the thalamic-reticular and thalamocortical mechanisms.

Sleep Spindles and Intellectual Ability: Epiphenomenon or Directly Related?

PubMed

Fang, Zhuo; Sergeeva, Valya; Ray, Laura B; Viczko, Jeremy; Owen, Adrian M; Fogel, Stuart M

2017-01-01

Sleep spindles-short, phasic, oscillatory bursts of activity that characterize non-rapid eye movement sleep-are one of the only electrophysiological oscillations identified as a biological marker of human intelligence (e.g., cognitive abilities commonly assessed using intelligence quotient tests). However, spindles are also important for sleep maintenance and are modulated by circadian factors. Thus, the possibility remains that the relationship between spindles and intelligence quotient may be an epiphenomenon of a putative relationship between good quality sleep and cognitive ability or perhaps modulated by circadian factors such as morningness-eveningness tendencies. We sought to ascertain whether spindles are directly or indirectly related to cognitive abilities using mediation analysis. Here, we show that fast (13.5-16 Hz) parietal but not slow (11-13.5 Hz) frontal spindles in both non-rapid eye movement stage 2 sleep and slow wave sleep are directly related to reasoning abilities (i.e., cognitive abilities that support "fluid intelligence," such as the capacity to identify complex patterns and relationships and the use of logic to solve novel problems) but not verbal abilities (i.e., cognitive abilities that support "crystalized intelligence"; accumulated knowledge and experience) or cognitive abilities that support STM (i.e., the capacity to briefly maintain information in an available state). The relationship between fast spindles and reasoning abilities is independent of the indicators of sleep maintenance and circadian chronotype, thus suggesting that spindles are indeed a biological marker of cognitive abilities and can serve as a window to further explore the physiological and biological substrates that give rise to human intelligence.

Bisphosphonate Therapy (and Osteonecrosis of the Jaw)

MedlinePlus

... or other invasive dental procedures, a phenomenon called osteonecrosis of the jaw (see Right and note area ... doctors agree that there is an association between osteonecrosis of the jaw and bisphosphonates, although the drugs ...

Muscle fatigue in the temporal and masseter muscles in patients with temporomandibular dysfunction.

PubMed

Woźniak, Krzysztof; Lipski, Mariusz; Lichota, Damian; Szyszka-Sommerfeld, Liliana

2015-01-01

The aim of this study is to evaluate muscle fatigue in the temporal and masseter muscles in patients with temporomandibular dysfunction (TMD). Two hundred volunteers aged 19.3 to 27.8 years (mean 21.50, SD 0.97) participated in this study. Electromyographical (EMG) recordings were performed using a DAB-Bluetooth Instrument (Zebris Medical GmbH, Germany). Muscle fatigue was evaluated on the basis of a maximum effort test. The test was performed during a 10-second maximum isometric contraction (MVC) of the jaws. An analysis of changes in the mean power frequency of the two pairs of temporal and masseter muscles (MPF%) revealed significant differences in the groups of patients with varying degrees of temporomandibular disorders according to Di (P < 0.0000). The study showed an increase in the muscle fatigue of the temporal and masseter muscles correlated with the intensity of temporomandibular dysfunction symptoms in patients. The use of surface electromyography in assessing muscle fatigue is an excellent diagnostic tool for identifying patients with temporomandibular dysfunction.

Muscle Fatigue in the Temporal and Masseter Muscles in Patients with Temporomandibular Dysfunction

PubMed Central

Woźniak, Krzysztof; Lipski, Mariusz; Lichota, Damian

2015-01-01

The aim of this study is to evaluate muscle fatigue in the temporal and masseter muscles in patients with temporomandibular dysfunction (TMD). Two hundred volunteers aged 19.3 to 27.8 years (mean 21.50, SD 0.97) participated in this study. Electromyographical (EMG) recordings were performed using a DAB-Bluetooth Instrument (Zebris Medical GmbH, Germany). Muscle fatigue was evaluated on the basis of a maximum effort test. The test was performed during a 10-second maximum isometric contraction (MVC) of the jaws. An analysis of changes in the mean power frequency of the two pairs of temporal and masseter muscles (MPF%) revealed significant differences in the groups of patients with varying degrees of temporomandibular disorders according to Di (P < 0.0000). The study showed an increase in the muscle fatigue of the temporal and masseter muscles correlated with the intensity of temporomandibular dysfunction symptoms in patients. The use of surface electromyography in assessing muscle fatigue is an excellent diagnostic tool for identifying patients with temporomandibular dysfunction. PMID:25883949

Self-aligning fixture used in lathe chuck jaw refacing

NASA Technical Reports Server (NTRS)

Linn, C. C.

1965-01-01

Self-aligning tool positions and rigidly holds lathe chuck jaws for refacing and truing of the clamping surface. The jaws clamp the fixture in the manner of clamping a workpiece. The fixture can be modified to accommodate four-jawed checks.

Development of the muscles associated with the mandibular and hyoid arches in the Siberian sturgeon, Acipenser baerii (Acipenseriformes: Acipenseridae).

PubMed

Warth, Peter; Hilton, Eric J; Naumann, Benjamin; Olsson, Lennart; Konstantinidis, Peter

2018-02-01

The skeleton of the jaws and neurocranium of sturgeons (Acipenseridae) are connected only through the hyoid arch. This arrangement allows considerable protrusion and retraction of the jaws and is highly specialized among ray-finned fishes (Actinopterygii). To better understand the unique morphology and the evolution of the jaw apparatus in Acipenseridae, we investigated the development of the muscles of the mandibular and hyoid arches of the Siberian sturgeon, Acipenser baerii. We used a combination of antibody staining and formalin-induced fluorescence of tissues imaged with confocal microscopy and subsequent three-dimensional reconstruction. These data were analyzed to address the identity of previously controversial and newly discovered muscle portions. Our results indicate that the anlagen of the muscles in A. baerii develop similarly to those of other actinopterygians, although they differ by not differentiating into distinct muscles. This is exemplified by the subpartitioning of the m. adductor mandibulae as well as the massive m. protractor hyomandibulae, for which we found a previously undescribed portion in each. The importance of paedomorphosis for the evolution of Acipenseriformes has been discussed before and our results indicate that the muscles of the mandibular and the hyoid may be another example for heterochronic evolution. © 2017 Wiley Periodicals, Inc.

Masseter motor unit recruitment is altered in experimental jaw muscle pain.

PubMed

Minami, I; Akhter, R; Albersen, I; Burger, C; Whittle, T; Lobbezoo, F; Peck, C C; Murray, G M

2013-02-01

Some management strategies for chronic orofacial pain are influenced by models (e.g., Vicious Cycle Theory, Pain Adaptation Model) proposing either excitation or inhibition within a painful muscle. The aim of this study was to determine if experimental painful stimulation of the masseter muscle resulted in only increases or only decreases in masseter activity. Recordings of single-motor-unit (SMU, basic functional unit of muscle) activity were made from the right masseters of 10 asymptomatic participants during biting trials at the same force level and direction under infusion into the masseter of isotonic saline (no-pain condition), and in another block of biting trials on the same day, with 5% hypertonic saline (pain condition). Of the 36 SMUs studied, 2 SMUs exhibited a significant (p < 0.05) increase, 5 a significant decrease, and 14 no significant change in firing rate during pain. Five units were present only during the no-pain block and 10 units during the pain block only. The findings suggest that, rather than only excitation or only inhibition within a painful muscle, a re-organization of activity occurs, with increases and decreases occurring within the painful muscle. This suggests the need to re-assess management strategies based on models that propose uniform effects of pain on motor activity.

Common theme for drugs effective in overactive bladder treatment: Inhibition of afferent signaling from the bladder

PubMed Central

Hood, Brandy; Andersson, Karl-Erik

2013-01-01

The overactive bladder syndrome and detrusor overactivity are conditions that can have major effects on quality of life and social functioning. Antimuscarinic drugs are still first-line treatment. These drugs often have good initial response rates, but adverse effects and decreasing efficacy cause long-term compliance problems, and alternatives are needed. The recognition of the functional contribution of the urothelium/suburothelium, the autonomous detrusor muscle activity during bladder filling and the diversity of nerve transmitters involved has sparked interest in both peripheral and central modulation of overactive bladder syndrome/detrusor overactivity pathophysiology. Three drugs recently approved for treatment of overactive bladder syndrome/detrusor overactivity (mirabegron, tadalafil and onabotulinum toxin A), representing different pharmacological mechanisms; that is, β-adrenoceptor agonism, phosphodiesterase type 5 inhibition, and inhibition of nerve release of efferent and afferent transmitters, all seem to have one effect in common: inhibition of the afferent nervous activity generated by the bladder during filling. In the present review, the different mechanisms forming the pharmacological basis for the use of these drugs are discussed. PMID:23072271

Vibratory Adaptation of Cutaneous Mechanoreceptive Afferents

PubMed Central

Bensmaïa, S. J.; Leung, Y. Y.; Hsiao, S. S.; Johnson, K. O.

2007-01-01

The objective of this study was to investigate the effects of extended suprathreshold vibratory stimulation on the sensitivity of slowly adapting type 1 (SA1), rapidly adapting (RA), and Pacinian (PC) afferents. To that end, an algorithm was developed to track afferent absolute (I0) and entrainment (I1) thresholds as they change over time. We recorded afferent responses to periliminal vibratory test stimuli, which were interleaved with intense vibratory conditioning stimuli during the adaptation period of each experimental run. From these measurements, the algorithm allowed us to infer changes in the afferents’ sensitivity. We investigated the stimulus parameters that affect adaptation by assessing the degree to which adaptation depends on the amplitude and frequency of the adapting stimulus. For all three afferent types, I0 and I1 increased with increasing adaptation frequency and amplitude. The degree of adaptation seems to be independent of the firing rate evoked in the afferent by the conditioning stimulus. In the analysis, we distinguished between additive adaptation (in which I0 and I1 shift equally) and multiplicative effects (in which the ratio I1/I0 remains constant). RA threshold shifts are almost perfectly additive. SA1 threshold shifts are close to additive and far from multiplicative (I1 threshold shifts are twice the shifts). PC shifts are more difficult to classify. We used an I0 integrate-and-fire model to study the possible neural mechanisms. A change in transducer gain predicts a multiplicative change in I0 and I1 and is thus ruled out as a mechanism underlying SA1 and RA adaptation. A change in the resting action potential threshold predicts equal, additive change in I0 and I1 and thus accounts well for RA adaptation. A change in the degree of refractoriness during the relative refractory period predicts an additional change in I1 such as that observed for SA1 fibers. We infer that adaptation is caused by an increase in spiking thresholds

Additively manufactured sub-periosteal jaw implants.

PubMed

Mommaerts, M Y

2017-07-01

Severe bone atrophy jeopardizes the success of endosseous implants. This technical note aims to present the innovative concept of additively manufactured sub-periosteal jaw implants (AMSJIs). Digital datasets of the patient's jaws and wax trial in occlusion are used to segment the bone and dental arches, for the design of a sub-periosteal frame and abutments in the optimal location related to the dental arch and for the design of the suprastructure. The implants and suprastructure are three-dimensionally (3D) printed in titanium alloy. The provisional denture is 3D-printed in polymer. AMSJIs offer an alternative approach for patients with extreme jaw bone atrophy. This report refers to the use of this technique for full maxillary rehabilitation, but partial defects in either jaw and extended post-resection defects may also be approached using the same technique. This customized, prosthesis-driven reverse-engineering approach avoids bone grafting and provides immediate functional restoration with one surgical session. Copyright © 2017 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Equilibrium stellar systems with spindle singularities

NASA Technical Reports Server (NTRS)

Shapiro, Stuart L.; Teukolsky, Saul A.

1992-01-01

Equilibrium sequences of axisymmetric Newtonian clusters that tend toward singular states are constructed. The distribution functions are chosen to be of the form f = f(E, Jz). The numerical method then determines the density and gravitational potential self-consistently to satisfy Poisson's equation. For the prolate models, spindle singularities arise from the depletion of angular momentum near the symmetry axis. While the resulting density enhancement is confined to the region near the axis, the influence of the spindle extends much further out through its tidal gravitational field. Centrally condensed prolate clusters may contain strong-field regions even though the spindle mass is small and the mean cluster eccentricity is not extreme. While the calculations performed here are entirely Newtonian, the issue of singularities is an important topic in general relativity. Equilibrium solutions for relativistic star clusters can provide a testing ground for exploring this issue. The methods used in this paper for building nonspherical clusters can be extended to relativistic systems.

Convergence of excitatory and inhibitory hair cell transmitters shapes vestibular afferent responses.

PubMed

Holstein, Gay R; Rabbitt, Richard D; Martinelli, Giorgio P; Friedrich, Victor L; Boyle, Richard D; Highstein, Stephen M

2004-11-02

The vestibular semicircular canals respond to angular acceleration that is integrated to angular velocity by the biofluid mechanics of the canals and is the primary origin of afferent responses encoding velocity. Surprisingly, some afferents actually report angular acceleration. Our data indicate that hair-cell/afferent synapses introduce a mathematical derivative in these afferents that partially cancels the biomechanical integration and results in discharge rates encoding angular acceleration. We examined the role of convergent synaptic inputs from hair cells to this mathematical differentiation. A significant reduction in the order of the differentiation was observed for low-frequency stimuli after gamma-aminobutyric acid type B receptor antagonist administration. Results demonstrate that gamma-aminobutyric acid participates in shaping the temporal dynamics of afferent responses.

The firing characteristics of foot sole cutaneous mechanoreceptor afferents in response to vibration stimuli.

PubMed

Strzalkowski, Nicholas D J; Ali, R Ayesha; Bent, Leah R

2017-10-01

Single unit microneurography was used to record the firing characteristics of the four classes of foot sole cutaneous afferents [fast and slowly adapting type I and II (FAI, FAII, SAI, and SAII)] in response to sinusoidal vibratory stimuli. Frequency (3-250 Hz) and amplitude (0.001-2 mm) combinations were applied to afferent receptive fields through a 6-mm diameter probe. The impulses per cycle, defined as the number of action potentials evoked per vibration sine wave, were measured over 1 s of vibration at each frequency-amplitude combination tested. Afferent entrainment threshold (lowest amplitude at which an afferent could entrain 1:1 to the vibration frequency) and afferent firing threshold (minimum amplitude for which impulses per cycle was greater than zero) were then obtained for each frequency. Increases in vibration frequency are generally associated with decreases in expected impulses per cycle ( P < 0.001), but each foot sole afferent class appears uniquely tuned to vibration stimuli. FAII afferents tended to have the lowest entrainment and firing thresholds ( P < 0.001 for both); however, these afferents seem to be sensitive across frequency. In contrast to FAII afferents, SAI and SAII afferents tended to demonstrate optimal entrainment to frequencies below 20 Hz and FAI afferents faithfully encoded frequencies between 8 and 60 Hz. Contrary to the selective activation of distinct afferent classes in the hand, application of class-specific frequencies in the foot sole is confounded due to the high sensitivity of FAII afferents. These findings may aid in the development of sensorimotor control models or the design of balance enhancement interventions. NEW & NOTEWORTHY Our work provides a mechanistic look at the capacity of foot sole cutaneous afferents to respond to vibration of varying frequency and amplitude. We found that foot sole afferent classes are uniquely tuned to vibration stimuli; however, unlike in the hand, they cannot be independently

Effects of Jaw Clenching and Jaw Alignment Mouthpiece Use on Force Production During Vertical Jump and Isometric Clean Pull.