Interaction of Periodontal and Jaw Elevator Spindle Afferents in the Cerebellum – Sensory Calibration

Taylor, Anthony R.; Elias, Stephen A.

doi:10.1159/000118861

Cited by 21 publications

(13 citation statements)

References 13 publications

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“…Since not only spindle Ia but also spindle II afferents would be activated by ␥-MNs during the isometric contraction, there would also be a positive relationship between the activities of spindle II and PMR afferents, although their synaptic impacts on ␣-MNs are much smaller compared with spindle Ia afferents (Kishimoto et al 1998). Such a calibration mechanism may exist in the cerebellum as an internal model as postulated previously (Taylor and Elias 1984). This idea is also supported by the findings that cerebellar ablation abolished the facilitation of isometric contraction caused by the activity of ␥-MNs (Hidaka et al 1997Komuro et al 1999).…”

Section: Origin Of Illusionmentioning

confidence: 84%

Illusion caused by vibration of muscle spindles reveals an involvement of muscle spindle inputs in regulating isometric contraction of masseter muscles

Tsukiboshi

Sato

Tanaka

et al. 2012

Journal of Neurophysiology

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. Illusion caused by vibration of muscle spindles reveals an involvement of muscle spindle inputs in regulating isometric contraction of masseter muscles. J Neurophysiol 108: 2524 -2533, 2012. First published August 22, 2012 doi:10.1152/jn.00997.2011.-Spindle Ia afferents may be differentially involved in voluntary isometric contraction, depending on the pattern of synaptic connections in spindle reflex pathways. We investigated how isometric contraction of masseter muscles is regulated through the activity of their muscle spindles that contain the largest number of intrafusal fibers among skeletal muscle spindles by examining the effects of vibration of muscle spindles on the voluntary isometric contraction. Subjects were instructed to hold the jaw at resting position by counteracting ramp loads applied on lower molar teeth. In response to the increasing-ramp load, the root mean square (RMS) of masseter EMG activity almost linearly increased under no vibration, while displaying a steep linear increase followed by a slower increase under vibration. The regression line of the relationship between the load and RMS was significantly steeper under vibration than under no vibration, suggesting that the subjects overestimated the ramp load and excessively counteracted it as reflected in the emergence of bite pressure. In response to the decreasing-ramp load applied following the increasing one, the RMS hardly decreased under vibration unlike under no vibration, leading to a generation of bite pressure even after the offset of the negative-ramp load until the vibration was ceased. Thus the subjects overestimated the increasing rate of the load while underestimating the decreasing rate of the load, due to the vibration-induced illusion of jaw opening. These observations suggest that spindle Ia/II inputs play crucial roles both in estimating the load and in controlling the isometric contraction of masseter muscles in the jaw-closed position.

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Section: Origin Of Illusionmentioning

confidence: 84%

Illusion caused by vibration of muscle spindles reveals an involvement of muscle spindle inputs in regulating isometric contraction of masseter muscles

Tsukiboshi

Sato

Tanaka

et al. 2012

Journal of Neurophysiology

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“…It is also unique that the periodontal receptors and muscle spindles from jaw muscles have direct projections to the cerebellar cortex (Taylor and Elias, 1984;Donga and Dessem, 1993). It is thought that this direct connection can be used as a reliable signal of tooth contact, and this may be used to zero or recalibrate the spindle afferent discharges.…”

Section: Pmrs -Musclespindleinteraction Forcalibratingthe Positionof mentioning

confidence: 99%

Reflex Control of Human Jaw Muscles

Türker

2002

Critical Reviews in Oral Biology & Medicine

139

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Introduction The main function of the masticatory muscles is to break food down into pieces small enough to be swallowed. These are strong muscles that generate very large forces across very short distances and apply themvia rigid teeth. Such large forces can easily damage the teeth and their supporting tissues, tongue, cheeks, and the joints unless they are controlled precisely and effectively. There is evidence that the masticatory forces are controlled very precisely and that these forces change from bite to bite, depending on the consistency of the bolus. However, we do not fully understand this control mechanism. Unless the details of the mechanism that controls the masticatory forces in health and disease are thoroughly understood, the diagnosis and treatment of masticatory-related dysfunctions (such as temporomandibular dysfunction) will remain at the present "symptomatic" state.The aim of this review is to discuss what is known about the control of the human masticatory system and to propose a method for standardized investigation. This review is divided into six parts. The first part discusses the activation of human jaw muscle motoneurons by the central and peripheral sources. The second part discusses the receptors that are thought to contribute to the control of human mastication. In part 3, the reflexes elicited in human subjects are discussed. In part 4, simulated chewing experiments are discussed. In part 5, recording and analyzing methods are discussed, and a new method for estimating synaptic potential in human motoneurons is introduced. Finally, in part 6, three frequently asked questions are used to discuss the issues put forward in this review.Presently, our knowledge of mastication and its control by various receptors is patchy. Most of the work in this area comes from animal species with which investigators have used widely varying reduction techniques (anesthetization, decerebration, curarization, etc.). In these preparations, when nerve pathways are the subject of the study, the nerve to be stimulated is dissected free and teased so that one or a few identified nerve fibers are stimulated. The synaptic potential that is induced by this stimulation is recorded by means of microelectrodes that are placed within the central nervous system (reviewed in Lund, 1991;Linden, 1990). It is also possible for investigators to initiate "chewing" in animal preparations, and to study the effects of various receptor systems on the development of force (Lavigne et al ., 1987;.In humans, one must establish the connections of various afferents to the motoneurons that innervate the masticatory muscles under static or dynamic conditions to begin to understand the mechanism and control of mastication. The human work is challenging, since direct recording from motoneurons is not yet possible and precise stimulation of nerves is not easily controlled. Therefore, various indirect measurements have been used for the study of synaptic potential in human subjects. In most of these studies, afferent nerves are stimul...

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“…Muscle spindles and periodontal mechanoreceptors have direct projections to the cerebellar cortex. On the basis of this convergence, the cerebellum is able to alter fusimotor activity and to regulate the gain of muscle spindles appropriately by comparison of information from muscle spindle afferents and tooth contacts in intercuspation . This inter‐relationship might also be used for temporal recalibration of jaw muscle spindles , ensuring precise control of jaw motion into intercuspation.…”

mentioning

confidence: 99%

Precision of jaw‐closing movements for different jaw gaps

Hellmann

Becker

Giannakopoulos

et al. 2013

European J Oral Sciences

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Jaw-closing movements are basic components of physiological motor actions precisely achieving intercuspation without significant interference. The main purpose of this study was to test the hypothesis that, despite an imperfect intercuspal position, the precision of jaw-closing movements fluctuates within the range of physiological closing movements indispensable for meeting intercuspation without significant interference. For 35 healthy subjects, condylar and incisal point positions for fast and slow jaw-closing, interrupted at different jaw gaps by the use of frontal occlusal plateaus, were compared with uninterrupted physiological jaw closing, with identical jaw gaps, using a telemetric system for measuring jaw position. Examiner-guided centric relation served as a clinically relevant reference position. For jaw gaps ≤4 mm, no significant horizontal or vertical displacement differences were observed for the incisal or condylar points among physiological, fast, and slow jaw-closing. However, the jaw positions under these three closing conditions differed significantly from guided centric relation for nearly all experimental jaw gaps. The findings provide evidence of stringent neuromuscular control of jaw-closing movements in the vicinity of intercuspation. These results might be of clinical relevance to occlusal intervention with different objectives.

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Interaction of Periodontal and Jaw Elevator Spindle Afferents in the Cerebellum – Sensory Calibration

Cited by 21 publications

References 13 publications

Illusion caused by vibration of muscle spindles reveals an involvement of muscle spindle inputs in regulating isometric contraction of masseter muscles

Illusion caused by vibration of muscle spindles reveals an involvement of muscle spindle inputs in regulating isometric contraction of masseter muscles

Reflex Control of Human Jaw Muscles

Precision of jaw‐closing movements for different jaw gaps

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