The strength of the reflex response to sinusoidal stretch of monkey jaw closing muscles during voluntary contraction.

Goodwin, Guy M.; Hoffman, Donna S.; Luschei, Erich S.

doi:10.1113/jphysiol.1978.sp012332

Cited by 108 publications

(27 citation statements)

References 55 publications

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“…and force modulation (5 Hz and below), seems quite reasonable. A similar analysis for the monkey, with natural tremor as input 'noise' (Goodwin et al 1978), yields a second-order transfer characteristic but with a corner frequency of about 10 Hz. These observations support the contention that the jaw muscle of humans is considerably slower than that of monkeys.…”

Section: Transfer Characteristic Of Human Jaw Musclesmentioning

confidence: 85%

“…If either the reflex or muscular stiffness were known, the other, unknown stiffness could be calculated by vector arithmetic. In the study by Goodwin et al (1978) the stretch reflex could be eliminated and the muscle stiffness directly measured (the stiffness observed in active but unmodulated muscle). We do not have direct information on the muscle stiffness of human jaw muscles, but it seems possible at least to estimate its magnitude and phase, as a function of frequency, from other experiments.…”

Section: Discussionmentioning

confidence: 99%

“…responses to loading or stretch of jaw-closing muscles (Lamarre & Lund, 1975); however, the actual contribution of reflex-modulated muscle activity to resistance of the jaw to displacement can only be evaluated with respect to the stiffness contributed by the contracting muscle. With the monkey, it was possible to determine directly the inherent muscle stiffness by abolishing the reflex (Goodwin et al 1978). Since this could not be done with human subjects, we used, instead, the results of an experiment on the stretch reflex of the hindlimb muscles of the decerebrate cat (Rosenthal, McKean, Roberts & Terzuolo, 1970) in the actuator and the control system rather than in the beam between the position sensor and the biting point, however, so changes in the position signal, which were used for calculation of the jaw stiffness, were a good representation of the actual displacements applied to the mandible.…”

Section: Human Jaw Stretch Reflexmentioning

confidence: 99%

“…Voluntary force modulation at frequencies above 4 Hz proved to be very difficult, so the relationship between e.m.g. and force fluctuations for frequencies of 5-16 Hz was determined from the normal tremor that occurred when the subjects maintained a steady (not purposely modulated) isometric biting force of 10 N. The isometric force tremor of the human jaw, like that of the monkey jaw (Goodwin et al 1978), is composed of a relatively broad spectrum of frequencies.…”

Section: Human Jaw Stretch Reflexmentioning

confidence: 99%

“…Lamarre & Lund (1975) did not observe any longer-latency responses after the initial, presumably monosynaptic, response. Goodwin, Hoffman & Luschei (1978) measured the resistance of the monkey's jaw to imposed sinusoidal displacements during a controlled isometric bite and concluded from data obtained before and after destruction of the muscle spindle afferent fibres that resistance to displacement from reflex modulation of muscle activity was much larger than that due to muscle stiffness at stretch frequencies between 3 and 10 Hz.…”

Section: Introductionmentioning

confidence: 99%

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Evidence that the human jaw stretch reflex increases the resistance of the mandible to small displacements.

Cooker¹,

Larson²,

Luschei³

1980

The Journal of Physiology

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SUMMARY1. Small 'step' or sinusoidal displacements were imposed on the mandible while human subjects maintained an average biting force of 10 N. Phase-related changes in the force resisting sinusoidal displacement were used to determine the mechanical stiffness of the human mandibular system as a function of the frequency of stretching.2. Jaw-muscle electromyographic (e.m.g.) responses to 'step' stretches were of 8 msec latency and generated a very substantial force response. Jaw-muscle e.m.g. responses having longer latency were not observed. The force resisting displacement was phase-advanced at all frequencies. 4. Modulation of jaw muscle electrical activity evoked by sinusoidal stretches increased in amplitude as a function of increasing stretch frequency. E.m.g. modulation was 60-100 degrees advanced at frequencies of 1-10 Hz, but the phase decreased at higher frequencies, becoming negative (lagging stretch) at frequencies of 30 Hz and above. These characteristics are consistent with the idea that the jaw stretch reflex is dependent on jaw muscle spindle afferent fibres exciting jaw-closing motoneurones by relatively direct (but not necessarily monosynaptic) connexions.5. The relationship between jaw-muscle activity and voluntary fluctuations of isometric biting force suggests that human jaw muscles can be modelled as a secondorder linear 'filter'. The corner frequency for human jaw muscle is about 3 Hz; thus it would appear to be considerably slower than jaw muscle of monkeys.6. The reflex stiffness of the human mandible, estimated quantitatively on the assumption that human jaw muscle stiffness is similar to the intrinsic stiffness of the gastrocnemius of the cat, ranges between 5 and 9 N'mm at frequencies between 1 and 8 Hz. Since this reflex stiffness is about the same as muscle stiffness in this frequency range, we conclude that the stretch reflex of the human mandible contributes functionally to its postural stability.7. Reflex stiffness appears to be greater in the monkey mandible relative to muscle stiffness than in the human mandible. The difference is argued to be a manifestation of the difference in jaw muscle contraction speed between the two species.

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Section: Transfer Characteristic Of Human Jaw Musclesmentioning

confidence: 85%

Section: Discussionmentioning

confidence: 99%

Section: Human Jaw Stretch Reflexmentioning

confidence: 99%

Section: Human Jaw Stretch Reflexmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Evidence that the human jaw stretch reflex increases the resistance of the mandible to small displacements.

Cooker¹,

Larson²,

Luschei³

1980

The Journal of Physiology

Self Cite

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Serotonergic axonal contacts on identified cat trigeminal motoneurons and their correlation with medullary raphe nucleus stimulation

et al. 1997

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The innervation of the trigeminal motor nucleus by serotonergic fibers with cell bodies in the raphe nuclei pallidus and obscurus suggests that activation of this pathway may alter the excitability of trigeminal motoneurons. Thus, we recorded intracellular responses from cat jaw-closing (JC) andjaw-opening (JO) alpha-motoneurons evoked by raphe stimulation and used a combination of intracellular staining of horseradish peroxidase (HRP) and immunohistochemistry at the light and electron microscopic levels to examine the distribution of contacts made by serotonin (5-HT)-immunoreactive boutons on the two motoneurons types. Electrical stimulation applied to the nucleus raphe pallidus-obscurus complex induced a monosynaptic excitatory postsynaptic potential (EPSP) in JC (masseter) alpha-motoneurons and an EPSP with an action potential in JO (mylohyoid) alpha-motoneurons. The EPSP rise-times (time to peak) and half widths were significantly longer in the JC than in the JO motoneurons. The EPSPs were suppressed by systemic administration of methysergide (2 mg/kg). Six JC and seven JO alpha-motoneurons were well stained with HRP. Contacts were seen between 5-HT-immunoreactive boutons and the motoneurons. The JC motoneurons received a significantly larger number of the contacts than did the JO motoneurons. The contacts were distributed widely in the proximal three-fourths of the dendritic tree of JC motoneurons but were distributed on more proximal dendrites in the JO motoneurons. At the electron microscopic level, synaptic contacts made by 5-HT-immunoreactive boutons on motoneurons were identified. The present study demonstrated that JC motoneurons receive stronger 5-HT innervation, and this correlates with the fact that raphe stimulation caused larger EPSPs among these neurons than among JO motoneurons.

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Jaw‐muscle spindle afferent pathways to the trigeminal motor nucleus in the rat

Luo

Moritani

Dessem

2001

J of Comparative Neurology

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Neural pathways conveying proprioceptive feedback from the jaw muscles were studied in rats by combining retrograde and intracellular neuronal labeling. Initially, horseradish peroxidase was iontophoresed unilaterally into the trigeminal motor nucleus (Vmo). Two days later, 1-5 jaw-muscle spindle afferent axons located in the mesencephalic trigeminal nucleus were physiologically identified and intracellularly stained with biotinamide. Stained mesencephalic trigeminal jaw-muscle spindle afferent axon collaterals and boutons were predominantly distributed in the supratrigeminal region (Vsup), Vmo, dorsomedial trigeminal principal sensory nucleus (Vpdm), parvicellular reticular formation (PCRt), alpha division of the parvicellular reticular formation (PCRtA), and dorsomedial portions of the spinal trigeminal subnuclei oralis (Vodm), and interpolaris (Vidm). Numerous neurons retrogradely labeled with horseradish peroxidase from the trigeminal motor nucleus were found bilaterally in the PCRt, PCRtA, Vodm, and Vidm. Retrogradely labeled neurons were also present contralaterally in the Vsup, Vpdm, Vmo, peritrigeminal zone, and bilaterally in the dorsal medullary reticular field. Putative contacts between intracellularly stained mesencephalic trigeminal jaw-muscle spindle afferent boutons and trigeminal premotor neurons retrogradely labeled with horseradish peroxidase were found in the ipsilateral Vodm, PCRtA, and PCRt, as well as the contralateral Vsup, Vmo, Vodm, PCRt, and PCRtA. Thus, multiple disynaptic jaw-muscle spindle afferent-motoneuron circuits exist. These pathways are likely to convey long-latency jaw-muscle stretch reflexes and may contribute to stiffness regulation of the masticatory muscles.

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The strength of the reflex response to sinusoidal stretch of monkey jaw closing muscles during voluntary contraction.

Cited by 108 publications

References 55 publications

Evidence that the human jaw stretch reflex increases the resistance of the mandible to small displacements.

Evidence that the human jaw stretch reflex increases the resistance of the mandible to small displacements.

Serotonergic axonal contacts on identified cat trigeminal motoneurons and their correlation with medullary raphe nucleus stimulation

Jaw‐muscle spindle afferent pathways to the trigeminal motor nucleus in the rat

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