Evidence for pattern generator control of the effects of spindle afferent input during rhythmical jaw movements

1981 ◽  
Vol 59 (7) ◽  
pp. 707-712 ◽  
Author(s):  
Louis J. Goldberg ◽  
Scott H. Chandler
Keyword(s):  
Vertical Plane ◽  
Afferent Input ◽  
Digastric Muscle ◽  
Rhythmic Movements ◽  
Jaw Movements ◽  
Central Program ◽  
Afferent Fibers ◽  
Jaw Opening ◽  
Passive Stretch ◽  
Opening Phase

The following recordings were made during spontaneous rhythmic jaw movements in the anesthetized guinea pig: jaw movement in the vertical plane, electromyograms from the digastric muscle (a jaw opener), and intracellular recordings from motoneurons and spindle afferent fibers of the jaw-closer muscles.The rapid jaw-opening phase of these rhythmic movements is characterized by a marked increase in activity in the spindle afferent fibers of the jaw-closer muscles and a coincident pronounced hyperpolarization of the membranes of the jaw-closer motoneurons.It is proposed that the excitatory spindle afferent input evoked by passive stretch of the jaw-closer muscles resulting from a centrally programmed contraction of the jaw-opener muscles impinges upon closer motoneurons that have been hyperpolarized as part of the central program. The hyperpolarization inhibits the motoneurons and nullifies the effect of the spindle afferent input thereby assuring relaxation of the closer muscles and an unimpeded rapid jaw-opening movement.

Comparison of External Load Compensation During Rhythmic Arm Movements and Rhythmic Jaw Movements in Humans

1999 ◽  
Vol 82 (3) ◽  
pp. 1209-1217 ◽  
Author(s):  
J. H. Abbink ◽  
A. van der Bilt ◽  
F. Bosman ◽  
H. W. van der Glas ◽  
C. J. Erkelens ◽  
...  
Keyword(s):  
Biceps Brachii ◽  
Reflex Response ◽  
Reflex Activity ◽  
Digastric Muscle ◽  
Induced Responses ◽  
Rhythmic Movements ◽  
Jaw Muscles ◽  
Reflex Responses ◽  
Jaw Opening ◽  
Arm Muscles

Experiments were performed on human elbow flexor and extensor muscles and jaw-opening and -closing muscles to observe the effect on rhythmic movements of sudden loading. The load was provided by an electromagnetic device, which simulated the appearance of a smoothly increasing spring-like load. The responses to this loading were compared in jaw and elbow movements and between expected and unexpected disturbances. All muscles showed electromyographic responses to unexpected perturbations, with latencies of ∼65 ms in the arm muscles and 25 ms in the jaw. When loading was predictable, anticipatory responses started in arm muscles ∼200 ms before and in jaw muscles 100 ms before the onset of loading. The reflex responses relative to the anticipatory responses were smaller for the arm muscles than for the jaw muscles. The reflex responses in the arm muscles were the same with unexpected and expected perturbations, whereas anticipation increased the reflex responses in the jaw muscles. Biceps brachii and triceps brachii showed similar sensory-induced responses and similar anticipatory responses. Jaw muscles differed, however, in that the reflex response was stronger in masseter than in digastric. It was concluded that reflex responses in the arm muscles cannot overcome the loading of the arm adequately, which is compensated by a large centrally programmed response when loading is predictable. The jaw muscles, particularly the jaw-closing muscles, tend to respond mainly through reflex loops, even when loading of the jaw is anticipated. The differences between the responses of the arm and the jaw muscles may be related to physical differences. For example, the jaw was decelerated more strongly by the load than the heavier arm. The jaw was decelerated strongly but briefly, <30 ms during jaw closing, indicating that muscle force increased before the onset of reflex activity. Apparently, the force-velocity properties of the jaw muscles have a stabilizing effect on the jaw and have this effect before sensory induced responses occur. The symmetrical responses in biceps and triceps indicate similar motor control of both arm muscles. The differences in reflex activity between masseter and digastric muscle indicate fundamental differences in sensory feedback to the jaw-closing muscle and jaw-opening muscle.

Behavior of Jaw Muscle Spindle Afferents During Cortically Induced Rhythmic Jaw Movements in the Anesthetized Rabbit

1999 ◽  
Vol 82 (5) ◽  
pp. 2633-2640 ◽  
Author(s):  
O. Hidaka ◽  
T. Morimoto ◽  
T. Kato ◽  
Y. Masuda ◽  
T. Inoue ◽  
...  
Keyword(s):  
Firing Rate ◽  
Muscle Spindle ◽  
Muscle Activity ◽  
Muscle Spindles ◽  
Emg Activity ◽  
Spatiotemporal Pattern ◽  
Digastric Muscle ◽  
Dependent Manner ◽  
Jaw Movements ◽  
Jaw Opening

The regulation by muscle spindles of jaw-closing muscle activity during mastication was evaluated in anesthetized rabbits. Simultaneous records were made of the discharges of muscle spindle units in the mesencephalic trigeminal nucleus, masseter and digastric muscle activity (electromyogram [EMG]), and jaw-movement parameters during cortically induced rhythmic jaw movements. One of three test strips of polyurethane foam, each of a different hardness, was inserted between the opposing molars during the jaw movements. The induced rhythmic jaw movements were crescent shaped and were divided into three phases: jaw-opening, jaw-closing, and power. The firing rate of muscle spindle units during each phase increased after strip application, with a tendency for the spindle discharge to be continuous throughout the entire chewing cycle. However, although the firing rate did not change during the jaw-opening and jaw-closing phases when the strip hardness was altered, the firing rate during the power phase increased in a hardness-dependent manner. In addition, the integrated EMG activity, the duration of the masseteric bursts, and the minimum gape increased with strip hardness. Spindle discharge during the power phase correlated with jaw-closing muscle activity, implying that the change in jaw-closing muscle activity associated with strip hardness was caused by increased spindle discharge produced through insertion of a test strip. The increased firing rate during the other two phases may be involved in a long-latency spindle feedback. This could contribute to matching the spatiotemporal pattern of the central pattern generator to that of the moving jaw.

Coordination of cortically induced rhythmic jaw and tongue movements in the rabbit

1993 ◽  
Vol 69 (2) ◽  
pp. 569-584 ◽  
Author(s):  
Z. J. Liu ◽  
Y. Masuda ◽  
T. Inoue ◽  
H. Fuchihata ◽  
A. Sumida ◽  
...  
Keyword(s):  
Emg Activity ◽  
Suitable Model ◽  
Rhythmic Movements ◽  
Jaw Movements ◽  
Jaw Movement ◽  
Type D ◽  
Jaw Opening ◽  
Tongue Movements ◽  
Group 2 ◽  
Group 1

1. Rhythmic movements of the jaw, tongue, and hyoid that were induced by stimulation of the cortical masticatory area (CMA) were recorded cineradiographically in the anesthetized rabbit. Jaw movements were also recorded by a laser position detector. 2. The evoked jaw movements were classified into four types: small circular (type A), large circular (type B), large vertical (type C), and crescent-shaped (type D). Among these, types B and D resembled the jaw movements of the food transport cycle and those of the chewing cycle in a masticatory sequence. 3. Each type of jaw movement was associated with a particular pattern of tongue and hyoid movements. In general, the tongue protruded during jaw opening and retracted during jaw closure. The hyoid generally moved upward and forward during jaw opening but downward and backward during jaw closure. 4. Electromyograms (EMGs) were recorded from jaw muscles [masseter (Ma) and digastric (Di) muscles], extrinsic tongue muscles [styloglossus (Sg) and genioglossus (Gg) muscles], and hyoid muscles [sternohyoid (Sh) and geniohyoid (Gh) muscles] during cortically induced rhythmic jaw and tongue movements (CRJTMs). These muscles were classified into two groups: group 1 was activated mainly in the jaw opening phase, and group 2 was activated mainly in the jaw closing and power phases. The Di, Gg, and Gh were included in the former, and the Ma, Sg, and Sh were included in the latter. 5. The timings of EMG activation to a jaw movement cycle were relatively constant for the muscles of group 1, irrespective of the types of CRJTMs, whereas those for the muscles of group 2 altered considerably with the different types of CRJTMs. 6. Relationships of the integrated muscle activity between the Di and Gg and between the Di and Gh were significant, whereas those between the Ma and Sg and between the Ma and Sh were not. 7. When a small strip of polyurethane form of various degrees of hardness was inserted between the opposing molars during CRJTMs, EMG activity of the muscles of group 2 increased with the hardness of the strip. On the other hand, EMG activities of the muscles of group 1 were less affected by the same intraoral stimuli. 8. Two conclusions were reached: first, physiological properties of the CRJTMs and cortically induced rhythmic movements of the hyoid were essentially similar to those observed in natural mastication. This fictive mastication might thus be regarded as a suitable model for simulating natural mastication.(ABSTRACT TRUNCATED AT 400 WORDS)

Reciprocal Interactions between the Rhythmical Jaw Movements and the Jaw Opening Reflex in the Rat

1990 ◽  
Vol 44 (2) ◽  
pp. 440-453 ◽  
Author(s):  
Kazuo Saeki ◽  
Masahiro Ohta ◽  
Satoru Ishizuka ◽  
Makoto Iwasaki
Keyword(s):  
Jaw Movements ◽  
Reciprocal Interactions ◽  
Jaw Opening ◽  
Jaw Opening Reflex

scholarly journals INPUT-OUTPUT RELATION IN A FLEXOR REFLEX

1957 ◽  
Vol 41 (2) ◽  
pp. 297-306 ◽  
Author(s):  
David P. C. Lloyd
Keyword(s):  
Spinal Cord ◽  
Afferent Input ◽  
Surprising Result ◽  
Input Output ◽  
Flexor Reflex ◽  
Afferent Fibers ◽  
Closed Chain ◽  
Central Paths ◽  
Reflex Threshold ◽  
Reflex Discharge

Observations have been made upon a typical flexor reflex with the aim of disclosing the changes in amount, latency, and temporal configuration of reflex discharge that take place as afferent input is varied from zero to maximal for the band of cutaneous myelinated afferent fibers that extends upward from approximately 6 µ in diameter (group II fibers). Reflex threshold is reached at 6 to 12 per cent maximal afferent input. From threshold to maximal input the relation between input and amount of output is essentially linear, latency on the average decreases, the shorter central paths in general gain preference, but the known minimum pathway, one of three neurons, does not transmit unless aided by convergent activity. Flexor reflex discharge may occur in several bursts suggesting the existence of closed chain connections in the internuncial pools of the spinal cord. At any given input there is, in successively elicited reflexes, little correlation between latency and amount of discharge, at first sight a surprising result for each variable can be taken as a measure of excitability status of the motoneuron population. However, latency of discharge indicates excitability at the beginning of the reflex event whereas amount of discharge is an expression of excitability over the entire period of discharge. Given a constantly and rapidly fluctuating excitability absence of correlation between these variables would be an anticipated result.

The organization and activity patterns of the anterior and posterior heads of the guinea pig digastric muscle

1987 ◽  
Vol 58 (3) ◽  
pp. 496-509 ◽  
Author(s):  
A. Lev-Tov ◽  
M. Tal
Keyword(s):  
Guinea Pig ◽  
Activity Patterns ◽  
Motor Nucleus ◽  
Digastric Muscle ◽  
Fiber Types ◽  
Jaw Movements ◽  
Cross Sectional ◽  
Trigeminal Motor Nucleus ◽  
Facial Motor Nucleus ◽  
Early Activity

The structure and activity patterns of the anterior and posterior heads of the guinea pig digastric muscle (DG) were studied in ketamine-anesthetized guinea pigs. Collagen staining of longitudinal and transverse sections of the muscle revealed that the guinea pig DG is comprised of a unicompartmental anterior head (ADG) and a multicompartmental posterior head (PDG). The two heads are separated by a thin tendinous inscription that, unlike the intermediate tendon of the DG in humans, is not attached to the hyoid bone. The motor nuclei of the guinea pig DG were reconstructed using retrograde labeling with horseradish peroxidase. The motoneurons of the ADG were clustered in a longitudinal column within the trigeminal motor nucleus. The motoneurons of the PDG were segregated into two clusters within the facial motor nucleus. The cross-sectional areas of the ADG and PDG motoneuron somata exhibited unimodal frequency distributions and the average soma area was larger for ADG than PDG motoneurons. Histochemical characterization of ADG and PDG revealed that the two muscle heads contained the three main histochemical types of muscle fibers identified in limb muscles. The frequency distribution of fiber types in ADG and PDG were not significantly different. Both muscle heads were predominantly fast with slow oxidative fibers accounting for only 1.1 and 0.3% of the fibers in narrow dorsal regions of ADG and PDG, respectively, and 13.6 and 12.9% in the more ventral regions of ADG and PDG, respectively. Simultaneous recordings of EMGs from the ADG and PDG were carried out during spontaneously occurring rhythmical jaw movements. These recordings revealed a high degree of synchrony between the activities of the two heads, although differences were observed in the onset and duration of the EMG bursts. Activity in the PDG preceded activity in the ADG in most of the rhythmical cycles and persisted longer. The differences in latencies of time-locked EMGs evoked in the ADG and PDG by four-pulse cortical stimulation were much smaller than those observed between the activity bursts of the two heads during rhythmical jaw movements. It is suggested that the early activity in the PDG is accounted for by shorter central conduction times in the pathways onto it and/or by higher recruitability of its motor units. The early activity in PDG may serve to optimize the location of ADG on its length-tension curve prior to and during the active state.

Effect of upper airway negative pressure on proprioceptive afferents from the tongue

1999 ◽  
Vol 86 (4) ◽  
pp. 1396-1401 ◽  
Author(s):  
A. Brancatisano ◽  
P. Davis ◽  
T. van der Touw ◽  
J. R. Wheatley
Keyword(s):  
Hypoglossal Nerve ◽  
Upper Airway ◽  
Rapid Onset ◽  
Firing Frequency ◽  
Tongue Muscle ◽  
Airway Mucosa ◽  
Afferent Fibers ◽  
Before And After ◽  
Proprioceptive Afferents ◽  
Passive Stretch

We examined whether receptors in the tongue muscle respond to negative upper airway pressure (NUAP). In six cats, one hypoglossal nerve was cut and its distal end was prepared for single-fiber recording. Twelve afferent fibers were selected for study on the basis of their sensitivity to passive stretch (PS) of the tongue. Fiber discharge frequency was measured during PS of the tongue and after the rapid onset of constant NUAP. During PS of 1–3 cm, firing frequency increased from 17 ± 7 to 40 ± 11 (SE) Hz ( P < 0.01). In addition, 8 of the 12 fibers responded to NUAP (−10 to −30 cmH2O), with firing frequency increasing from 23 ± 9 to 41 ± 9 Hz ( P < 0.001). In two fibers tested, the increase in firing frequency in response to NUAP was not altered by topical anesthesia (10% lignocaine) applied liberally to the entire upper airway mucosa. Our results demonstrate that afferent discharges from the hypoglossal nerve are elicited by 1) stretching of the tongue and 2) NUAP before and after upper airway anesthesia. We speculate that activation of proprioceptive mechanoreceptors in the cat’s tongue provides an additional pathway for the reflex activation of upper airway dilator muscles in response to NUAP, independent of superficially located mucosal mechanoreceptors.

Characteristics of afferent fiber innervation on acupuncture points zusanli

1983 ◽  
Vol 245 (4) ◽  
pp. R606-R612 ◽  
Author(s):  
G. W. Lu
Keyword(s):  
Peroneal Nerve ◽  
Afferent Fiber ◽  
Suppressive Effect ◽  
Structure And Function ◽  
Acupuncture Points ◽  
Digastric Muscle ◽  
Movement Response ◽  
Afferent Fibers ◽  
And Function ◽  
Peroneal Nerve Stimulation

Acupoint zusanli is one of the most effective points in traditional Chinese medicine. Needling point zusanli has a significant suppressive effect on jaw movement response (JMR) and electromyogram of digastric muscle (dEMG) induced by peroneal nerve stimulation. This effect is weakened or abolished by sectioning the peroneal nerve and blocking A-beta- and some A-delta-fibers in the nerve. When the point zusanli is stimulated electrically a larger-than-normal proportion of A-beta-fibers is activated. Local afferent fiber composition at this point contains more myelinated fibers, more large-sized fibers, and more A-beta-fibers than nonacupoints. This predominance of large afferent fibers in the composition and activity of point zusanli is thought to be one of the fundamental characteristics of the point in regard to its structure and function and contributes to its powerful acupuncture effect.

Gating of Afferent Input by a Central Pattern Generator

1999 ◽  
Vol 81 (2) ◽  
pp. 950-953 ◽  
Author(s):  
Ralph A. DiCaprio
Keyword(s):  
Central Pattern Generator ◽  
Sensory Input ◽  
Motor Pattern ◽  
Pattern Generator ◽  
Afferent Input ◽  
Inhibitory Input ◽  
Cycle Period ◽  
Intracellular Recordings ◽  
Afferent Fibers ◽  
Sufficient Magnitude

Gating of afferent input by a central pattern generator. Intracellular recordings from the sole proprioceptor (the oval organ) in the crab ventilatory system show that the nonspiking afferent fibers from this organ receive a cyclic hyperpolarizing inhibition in phase with the ventilatory motor pattern. Although depolarizing and hyperpolarizing current pulses injected into a single afferent will reset the ventilatory motor pattern, the inhibitory input is of sufficient magnitude to block afferent input to the ventilatory central pattern generator (CPG) for ∼50% of the cycle period. It is proposed that this inhibitory input serves to gate sensory input to the ventilatory CPG to provide an unambiguous input to the ventilatory CPG.

Modification of mastication and respiration during swallowing in the adult human

1995 ◽  
Vol 74 (4) ◽  
pp. 1509-1517 ◽  
Author(s):  
D. H. McFarland ◽  
J. P. Lund
Keyword(s):  
Respiratory Rhythm ◽  
Phase Relationship ◽  
Head Movements ◽  
Rib Cage ◽  
Jaw Opening ◽  
Prolonged Apnea ◽  
Pattern Generators ◽  
Analysis System ◽  
Respiratory Movements ◽  
Opening Phase

1. The normal interactions between respiration, mastication, and swallowing were studied in seated adult humans. Respiratory movements and movements of the larynx were recorded with mercury-elastic strain gauges placed around the rib cage and neck. A rigid body containing infrared-emitting diodes (IREDs) was attached to the forehead, and a single IRED was applied to the chin. Jaw and head movements were transduced using the OPTOTRAK spatial motion analysis system. Recordings were made before, during, and after the mastication of pieces of carrot. 2. Movements of the larynx were used as a marker for swallowing. Measurements were made of the duration of masticatory and respiratory cycles, and the phase relationship between the two rhythms was determined. Deviations in masticatory and respiratory movements during swallowing were detected; the phases of the masticatory and respiratory cycles in which the deviations occurred were determined, and the interval between each deviation and the swallowing marker was calculated. 3. Three characteristic swallowing patterns were observed: interposed, terminal, and spontaneous. Interposed swallows occurred within a masticatory sequence, terminal swallows ended the sequence, and spontaneous swallows occurred sporadically between masticatory sequences. 4. Results revealed that mastication could have a profound effect on the respiratory rhythm in some subjects. One subject, whose data were excluded from further analyses, became apneic for a long period, followed by short and shallow breaths near the end of the masticatory sequence. In most subjects, respiratory rate increased during mastication and then dropped below baseline as soon as mastication ended. The end-inspiration diameter of the rib cage tended to decrease in the preswallow period and increase postmastication relative to baseline. 5. There was a weak but significant tendency for inspiration to begin during the jaw opening phase of mastication, but phase coupling did not become stronger as swallowing was approached. 6. Deviations in respiration during swallowing occurred during the late expiratory phase of the breathing cycle. Swallows within a masticatory sequence occurred most frequently during the early opening phase of the masticatory cycle, and terminal swallows occurred after the end of the sequence with the mandible in the resting, postural position. Swallowing temporarily reset both the masticatory and respiratory rhythms. Most swallows prolonged the duration of one or two respiratory cycles, however; swallows were often repetitive, and in some subjects two or three swallows fell within a single respiratory cycle, prolonging it for several seconds. 7. A tight temporal relationship was observed between deviations in respiration and the swallowing marker: all deviations occurred before or coincident with the marker. The time of deviations in mastication relative to the swallowing marker depended on swallow type. There was no link between the start of pauses in the two rhythms, suggesting that the commands from the swallowing central pattern generator to the other two pattern generators are independent. 8. We suggest that disordered coordination of mastication and swallowing with respiration may cause prolonged apnea in susceptible individuals.

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