Vertical Jaw Movements Research Articles

Topographical effects of D1-like dopamine receptor agonists on orofacial movements in mice and their differential regulation via oppositional versus synergistic D1-like: D2-like interactions: cautionary observations on SK&F 82958 as an anomalous agent

Using a novel procedure, the regulation of individual topographies of orofacial movement in the mouse by oppositional versus cooperative/synergistic D1-like: D2-like dopamine receptor interactions was studied. The D1-like agonists SK&F 38393 and SK&F 83959 each induced vertical, but not horizontal, jaw movements, together with tongue protrusions and incisor chattering; however, SK&F 82958 induced a different profile which, consistent with other neurochemical and neurophysiological studies, suggests that this agent shows anomalous properties relative to other D1-like agonists. When given alone, the D2-like agonist quinpirole reduced horizontal jaw movements and incisor chattering. On coadministration, both SK&F 38393- and SK&F 83959-induced vertical jaw movements and tongue protrusions were inhibited by quinpirole, while SK&F 82958 again showed an anomalous profile. These findings indicate that, in the mouse, vertical jaw movements and tongue protrusions are regulated by oppositional D1-like: D2-like interactions, and appear to involve a D1-like receptor that is not coupled to adenylyl cyclase, whereas horizontal jaw movements are inhibited by D2-like receptors. Additionally, results obtained using SK&F 82958 as a probe for D1-like mechanisms should be treated with considerable caution until they are confirmed using other D1-like agonists.

CHEWING BEHAVIOR OBSERVED AT DIFFERENT STAGES OF MASTICATION FOR SIX FOODS, STUDIED BY ELECTROMYOGRAPHY AND JAW KINEMATICS IN YOUNG AND ELDERLY SUBJECTS

ABSTRACTi

Control of human mandibular posture during locomotion.

Mandibular movements and masseter muscle activity were measured in humans during hopping, walking and running to determine whether reflexes contribute to the maintenance of jaw position during locomotion. In initial experiments, subjects hopped so that they landed either on their toes or on their heel. Landing on the toes provoked only small mandibular movements and no reflex responses in the masseter electromyogram (EMG). Landing on the heels with the jaw muscles relaxed caused the mandible to move vertically downwards relative to the maxilla, and evoked a brisk reflex response in the masseter at monosynaptic latency. Neither this relative movement of the mandible nor the reflex was seen when the teeth were clenched: hence the reflex is not the result of vestibular activation during head movement. The same variables were measured in a second series of experiments while subjects stood, walked and ran at various speeds and at various inclinations on a treadmill. During walking, the vertical movements of the head and therefore the mandible were slow and small, and there was no tonic masseter EMG or gait-related activity in the jaw-closing muscles. When subjects ran, the vertical head and jaw movement depended on the running speed and the inclination of the treadmill. Landing on the heels induced larger movements than landing on the toes. About 10 ms after each foot-strike, the mandible moved downwards relative to the maxilla, thereby stretching the jaw-closing muscles and activating them at segmental reflex latency. This caused the mandible to move back upwards. The strength of the reflex response was related to the speed and amplitude of the vertical jaw movement following landing. It is concluded that, during walking, the small, slow movements of the mandible relative to the maxilla are subthreshold for stretch reflexes in the jaw muscles: i.e. the mandible is supported by visco-elasticity of the soft tissues in the masticatory system. However, the brisker downward movements of the mandible after heel-landing during hopping and running evoke segmental reflex responses which contribute to the active maintenance of the posture of the mandible. This is a unique demonstration of how a stretch reflex operates to maintain posture under entirely natural conditions.

Studying articulatory variability using functional data analysis

This paper examines articulatory variability across repetitions using functional data analysis. In this analysis, signals are time-normalized using a smooth function of time. The magnitude of the time-warping function provides an index of phasing (temporal) variability; a separate index of amplitude variability is calculated from the time-normalized signal. Here, lip, jaw, and tongue movements in vowel–consonant–vowel sequences recorded using a magnetometer were used for the analysis. Preliminary results suggest articulator specific patterns of variability. Thus vertical jaw movements showed small amplitude variability for alveolar consonants, like /s, t/. As expected, the amplitude variability of the tongue tip was small during alveolar consonants, where the tip is in contact with the alveolar ridge. However, the amplitude of the tongue tip movement varied considerably at the release of alveolar stops. The horizontal and vertical movements of the same articulator often showed a different amount of amplitude variability. For example, during the movement from the first to the second vowel in /api/, the tongue body showed small vertical and large horizontal variability. The results will be discussed in terms of articulatory, acoustic, and perceptual constraints on speech production. [Work supported by CNPq, Brazil, and NIH.]

Phenotypic resolution of spontaneous and D 1-like agonist-induced orofacial movement topographies in congenic dopamine D 1A receptor ‘knockout’ mice

A novel system was used to assess the role of D 1-like dopamine receptors in distinct topographies of orofacial movements in mice with congenic D 1A receptor knockout. Under spontaneous conditions, vertical jaw movements in wildtypes declined with time at a rate that was reduced in D 1A mutants, while horizontal jaw movements emerged progressively in wildtypes but not in D 1A mutants; tongue protrusions were absent in D 1A mutants, while incisor chattering was initially reduced in D 1A mutants but rose subsequently to reach the level of wildtypes. D 1A receptors exert a topographically specific role in regulating individual spontaneous orofacial movements, and these involve interactions with psychomotor processes which ‘sculpt’ behavioural change over time. The anomalous D 1-like agonist SK&F 83959, which fails to stimulate, and indeed inhibits the stimulation of adenylyl cyclase induced by dopamine, readily stimulated vertical jaw movements, tongue protrusions and incisor chattering, and these response topographies were absent in D 1A mutants. These results suggest that D 1A receptors may exert some form of permissive role over orofacial topographies initiated via a novel, putative D 1-like site not linked to adenylyl cyclase, or that some D 1A receptors might be coupled to a transduction system other than adenylyl cyclase.

A postero-anterior videofluorographic study of the intra-oral management of food in man

Recent studies of the manipulation and reduction of food in the human mouth have used lateral-projection videofluorography (VFG) and so have concerned antero-posterior food movement. To determine the degree to which (a) food was chewed bilaterally as opposed to unilaterally, (b) the frequency of side changes, (c) the contribution of tongue and cheek activity to food manipulation, and (d) the effect of food consistency on these activities, nine young adults were recorded eating 7 g cubes of four foods (banana, biscuit (cookie) and two types of meat: ‘tender’ and ‘tough’) in the postero-anterior projection. Videotapes recorded at 30 frames/s were acquired to disk; data were analysed as single frames and in slow-motion. As expected, the meat samples, being fibrous, required more chewing and manipulation, allowing details of the process to be established. Food was ingested in the midline; the tongue then positioned the cube on the occlusal plane of one side by a combination of pushing, tilting and twisting movements before any occlusal contact (stage I transport). During processing, food was kept on the occlusal surface by a combination of rhythmic tongue-pushing moving the food buccally (41% of cycles), and cheek-pushing (28% of cycles) returning it in the lingual direction. This reciprocating movement ensured that different parts of the food were subjected to occlusal force in successive cycles. Bilateral chewing was common and associated with either: (a) a near-symmetrical closing movement with tooth–food–tooth contact occurring almost simultaneously on both sides, or (b) an identifiable ‘active side’ but a jaw movement extended medially to carry the lower molars through a power stroke on the ‘balancing’ side. During the sequence, food requiring further chewing might be moved to the erstwhile balancing-side (balancing-side shift); or across the mouth to the tooth row or vestibule on the other side and ‘stored’ for later reduction (segregation shift). Towards the end of the sequence, triturated material was moved to the midline (aggregation shift) for bolus formation and deglutition. While distinct patterns of mediolateral and vertical jaw movements seem to be associated with shift and transport cycles, these connections have not yet been established with sufficient robustness to support predictions of intra-oral events from jaw movement profiles alone.

Effect of 5-HT 1A and 5-HT 2A/2C receptor modulation on neuroleptic-induced vacuous chewing movements

Tardive dyskinesia is a serious motor side effect of chronic neuroleptic therapy. Chronic treatment or rats with neuroleptics leads to the development of abnormal oral movements called vacuous chewing movements. Vacuous chewing movements in rats are widely accepted as an animal model of tardive dyskinesia. Atypical antipsychotics such as clozapine and rispiridone are associated with a lower incidence of extrapyramidal side effects and tardive dyskinesia. The present study was aimed to explore the role of 5-HT 1A, 5-HT 2A/2C receptors in the expression of neuroleptic-induced orofacial dyskinesia. In the present study rats were chronically (for 21 days) treated with haloperidol (1.5 mg/kg, i.p.) to elicit vacuous chewing movements. The neuroleptic-induced vacuous chewing movements, viz., vertical jaw movements, tongue protrusions and bursts of jaw tremors, were counted during a 5-min observation period. Acute treatment with 8-hydroxy-2-(di- n-propylamino) tetralin (8-OH-DPAT), a 5-HT 1A receptor agonist, dose-dependently (0.05, 0.1 and 0.2 mg/kg, i.p.) reduced the haloperidol-induced vacuous chewing movements and headshakes. Both acute and chronic administration of seganserin, ketanserin and ritanserin, 5-HT 2A/2C receptor antagonists, also reduced haloperidol-induced vacuous chewing movements in a dose-dependent (0.05, 0.1 and 0.2 mg/kg, i.p.) manner. In acute studies a higher dose of ritanserin (1 mg/kg) but not ketanserin (1 mg/kg) increased vacuous chewing movements, whereas a higher dose of seganserin (1 mg/kg) did not have any effect on vacuous chewing movements. All the drugs reduced haloperidol-induced headshakes in a dose-dependent fashion. These findings indicate that the serotonergic system, and particularly 5-HT 1A and 5-HT 2A/2C receptors, may be involved in haloperidol-induced orofacial dyskinesia, and that 5-HT receptors may provide novel targets for the development of drugs that can be used to reverse or prevent the extrapyramidal side effects associated with long-term antipsychotic treatment.

Excitatory mechanisms in neuroleptic-induced vacuous chewing movements (VCMs): possible involvement of calcium and nitric oxide

Tardive dyskinesia (TD) is a serious motor side-effect of chronic neuroleptic therapy. Chronic treatment with neuroleptics leads to the development of oral abnormal movements in rats known as vacuous chewing movements (VCMs). Vacuous chewing movements in rats have been widely accepted as an animal model of tardive dyskinesia. Chronic blockade of D2 inhibitory dopamine (DA) receptors localized on glutamatergic terminals in the striatum leads to the persistent enhanced release of glutamate that kills the striatal output neurons. The object of the present study was to explore the role of glutamatergic modulation on the neuroleptic-induced VCMs. Rats were chronically (for 21 days) treated with haloperidol (1.5 mg/kg, i.p.) to produce VCMs. The neuroleptic-induced VCMs viz., vertical jaw movements, tongue protrusions and bursts of jaw tremors, were counted during a 5 min observation period. Dizocilpine, a non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist, dose dependently (0.02 and 0.05 mg/kg) reduced haloperidol-induced VCMs. Felodipine (5 and 10 mg/kg), an L-type calcium-channel blocker, also significantly reduced the VCM count. N-omega-nitro-L-arginine methyl ester (L-NAME) (25 and 50 mg/kg), a nitric oxide synthase inhibitor, also reduced the VCM count in an L-arginine-sensitive manner. In conclusion, the findings of the present study indicated NMDA receptor involvement in haloperidol-induced VCMs, and also suggested the possible involvement of calcium and nitric oxide in haloperidol-induced VCMs.

Topographical assessment and pharmacological characterization of orofacial movements in mice: dopamine D 1-like vs. D 2-like receptor regulation

A novel procedure for the assessment of orofacial movement topographies in mice was used to study, for the first time, the individual and interactive involvement of dopamine D 1-like vs. D 2-like receptors in their regulation. The dopamine D 1-like receptor agonists A 68930 ([1 R,3 S]-1-aminomethyl-5,6-dihydroxy-3-phenyl-isochroman) and SK&F 83959 (3-methyl-6-chloro-7,8-dihydroxy-1-[3-methyl-phenyl]-2,3,4,5-tetrahydro-1 H-3-benzazepine) each induced vertical jaw movements with tongue protrusions and incisor chattering. The dopamine D 1-like receptor antagonists SCH 23390 ([ R]-3-methyl-7-chloro-8-hydroxy-1-phenyl-2,3,4,5-tetrahydro-1 H-3-benzazepine) and BW 737C ([ S]-6-chloro-1-[2,5-dimethoxy-4-propylbenzyl]-7-hydroxy-2-methyl-1,2,3,4-tetrahydroisoquinoline) antagonised these responses, while the dopamine D 2-like receptor antagonist YM 09151-2 ( cis- N-[1-benzyl-2-methyl-pyrrolidin-3-yl]-5-chloro-2-methoxy-4-methylaminobenzamide) attenuated those to SK&F 83959 and released horizontal jaw movements. These findings suggest some role for a dopamine D 1-like receptor that is coupled to a transduction system other than/additional to adenylyl cyclase, and for dopamine D 1-like:D 2-like receptor interactions, in the regulation of individual orofacial movement topographies in the mouse. This methodology will allow the use of knockout mice to clarify the roles of individual dopamine receptor subtypes in their regulation.

A comparison of particle breakdown during chewing by guanacos (Lama guanicoe) and sheep

To date, attempts to account for reported differences in digestive efficiency of camelids and ruminants have focused on factors such as stomach motility and the retention time of feed particles. The physical breakdown of forage into particles small enough to pass through the reticulo-omasal orifice is one of the major factors influencing the rate of passage of digesta from the reticulo-rumen in ruminants. Two of the main processes involved in particle size reduction are chewing (pre- and post-regurgitation) and microbial fermentation. While the characteristic vertical and horizontal jaw movement which occurs during mastication in the camelid is believed to allow for efficient use of the premolars and molars in cutting and grinding fibrous feeds, there have been no comparative studies to verify this, and to assess the contribution of chewing to differences in digestibility coefficients. The aim of this experiment was to directly compare particle breakdown during chewing by guanacos and sheep.

相互相関法からみた骨格性下顎前突症患者のそしゃく筋筋活動パターン

The purpose of this study was to investigate EMG profiles of masticatory muscles in orthognathic surgery patients with mandibular prognathism during deliberate unilateral gum chewing.Vertical jaw movement and EMG activities from bilateral anterior temporal, masseter, and anterior belly of digastric muscles were recorded simultaneously from 12 healthy adults and 12 patients. EMG signal was divided according to the period of the maximum opening position of vertical jaw movement. EMG profiles of the chewing stroke were accomplished by normalizing each period to 100%. Normalization was achieved by setting the mean value of each EMG over the chewing cycle to 100%. The relationship of the EMG profile between normal subjects and patients was evaluated. The degree of similarity and the displacement for each EMG profile in all muscles was investigate by using a cross-correlation technique.The results were as follows:1. EMG profiles of patients were different for the “Peak” vale and “Duration” of the activity from those of normal subjects.2. The similarity was little, and great displacement was found in patients.3. In patients, the similarity and displacement of EMG profiles had large value on the working side.

食品テクスチャーの違いがそしゃく筋筋活動パターンに与える影響

A study was conducted for the purpose of grasping the influence of food characteristics on electromyographic (EMG) patterns during mastication. Cheese, kamaboko, takuan, senbei, surume and gumi were used as test food. Vertical jaw movement and EMG activities were recorded simultaneously from 10 healthy adults. EMG signal was divided according to the period of the maximum opening position of vertical jaw movement.EMG profile for chewing stroke was accomplished by normalizing each period to 100% from the beginning of mastication to swallowing. The relationship between the texture of test materials and the EMG profiles was evaluated.The obtained results were as follows:1. The EMG profile of each test material showed various patterns. The degree of variability in the masseter was larger than that in the temporal and digastric muscles.2. Owing to the delay of the onset of EMG activity, the duration of activity in the temporal and masseter muscle was shortened as mastication progressed.3. Cheese showed the largest difference between the beginning of mastication and just before swallowing in the EMG profile of the temporal and masseter muscles. Surume showed least change in the EMG profile.

Speech Motor Control in Parkinson’s Disease: A Comparison between a Clinical Assessment Protocol and a Quantitative Analysis of Mandibular Movements

Nine individuals with Parkinson's disease (PD) and nine normal control subjects, matched for sex and age, were compared on a standardized assessment protocol for dysarthria. Simple measures of hand and gait motility were also obtained. A kinematic analysis of vertical jaw movements during speech was performed by using an optoelectronic technique. The PD subjects were examined during both induced off L-dopa and on L-dopa states, and their performance was compared between the two conditions. Significant group differences were found for all kinematic measures during a syllable repetition task, as well as for the total dysarthria test scores and certain individual test items. Implications and clinical usefulness of the kinematic approach to the study of oral motor functions are discussed.

Predicting foodstuff from jaw dynamics during masticatory crushing in man

In previous in vitro experiments using an Instron instrument, each test food was found to have characteristic textural properties. In vivo experiments were now made (1) to determine the degree to which variations in the vertical jaw movements during the crushing phase of mastication can be explained by the inherent properties of the foodstuff being chewed, and (2) to establish the degree to which the foodstuff being chewed can be identified by certain features of the jaw dynamics. Five adults were used for chewing tasks with standardized pieces of beef, carrot or peanut. Each subject made two trials with each foodstuff. The movement of the lower incisal point was monitored; features of movement associated with jaw closing in the first chewing cycle were considered. Five of these features were not suitable to categorize the various test foods. Each of the remaining 4, however, was able to distinguish either one food from the 2 others (2 cases), or one from another (2 cases). Pattern recognition techniques based upon principal component analysis could differentiate jaw closing patterns associated with chewing beef from those involving peanut or carrot. The extent to which peanut could be distinguished from carrot was not as predictable as the categorization of peanut or carrot versus beef. Cross-correlation of in vitro force-time breakage characteristics and the jaw movement data showed that on average 52% of the variation in the vertical jaw movement during crushing of food could be explained by the inherent properties of the food. Because the masticatory apparatus acts as a low-pass filter, the high-frequency components of food breakage characteristics found in vitro were attenuated in vivo. It appears that the inherent filter properties of the masticatory apparatus limit the range of sensory and motor function of the jaw.

ラットのリズム顎運動と開口反射との相互作用

Reciprocal interactions between the rhythmical jaw movements (RJM) and the jaw opening reflex (JOR) were investigated in ketamine anesthetized rats. The tooth pulp of the right lower incisor was electrically stimulated with a bipolar steel wire electrode. The electrical activities of the ipsilateral trigeminal spinal nucleus caudalis (SpNc), the ipsilateral mylohyoid nerve (Myl N) and the contralateral cerebral peduncle were recorded. Vertical jaw movements were recorded through a transducer connected to a dental steel bar fixed to the roots of the lower incisors. Neuronal activities of the cerebral peduncle were observed prior to and during the RJM and the maximum activity occurred in a few initial cycles of the RJM. The JOR related activities were modulated phase-dependently during the RJM. The initial component of the primary afferent activities in the SpNc was facilitated in the late occlusal phase and the early opening phase and progressively inhibited from the late opening phase through the closing phase to the early occlusal phase. The late component of the primary afferent activities was tonically inhibited during the RJM with a slight phase-dependency. This tonic inhibition of the late component was thought to be due to primary afferent depolarization induced by the cerebral peduncular input in the SpNc. The Myl N activity was facilitated from the late occlusal phase to the peak opening phase and inhibited in the later closing phase and the early occlusal phase. This facilitation was thought to be induced by excitatory inputs from the brainstem pattern generator. The reflex jaw opening depended not only directly on the Myl N activity but also on the jaw position, reduced during the jaw opening and increased during the jaw closure. The RJM was also modulated by the JOR. The small JOR initiated or facilitated the RJM although the large JOR inhibited the RJM fixing the jaw in an opening position. The intermediate JOR modulated the RJM phase-dependently. This inhibition of the RJM was thought to be due to strong postsynaptic inhibition of the jaw closing motoneuron. The tooth pulp afferents could participate in control of the masticatory jaw movements as the other trigeminal sensory afferents.

Effect of gum hardness on chewing pattern

Chewing rhythms are set by a putative central pattern generator whose output is influenced by sensory feedback. In this study we assessed how an altered feedback imposed by changing the hardness of a gum bolus modifies the timing of chewing, the maximal gape, and the activity in the masseter muscle on the chewing side. Ten adult subjects with no orofacial dysfunction chewed a standard piece of soft or hard gum for at least 3 min in random order. Vertical jaw movements were recorded with a kinesiograph and activity of the masseter muscle was recorded and integrated from surface EMG electrodes. The subjects sat in a dental chair and viewed a video lecture to distract their attention from chewing; they were instructed to chew on the right molars. Cycle-by-cycle analysis showed that 9 of the 10 subjects chewed the hard gum more slowly than the soft with no significant change in gape. The increases in cycle duration were due to changes in the duration of the opening and occlusal phases. The duration of closing was not significantly changed even though the duration and level of masseter activity were both significantly increased. We conclude that gum hardness by altering proprioceptive feedback modifies the output of the masticatory central pattern generator in such a way that the temporal aspects of chewing and the output of the masseteric motor pool are affected.

Ｔａｐｐｉｎｇ運動時におけるこう合音と垂直的下がく運動との関係について

Ｔａｐｐｉｎｇ運動時におけるこう合音と垂直的下がく運動との関係について

Analysis, synthesis, and perception of visible articulatory movements

Significant advances in isolating the perceptually important properties of speech sounds followed the development of techniques for acoustical speech synthesis in the early 1950s. Prescription of spectro-temporal acoustical structure made it possible to manipulate individual acoustical parameters and thus to study the ways in which speech sounds were identified and discriminated. This paper reviews attempts to develop analogous facilities for studying the perception of visible, facial, articulatory movements in lipreading. A new approach, involving interrelated procedures for measuring, modelling, and animating displays of a talking face with computer graphics is described, along with a prototypic perceptual experiment. The results suggest that the important visible properties of point vowels may not be fully captured by descriptions of vertical jaw movements, horizontal and vertical oral opening and lip shape, even when vowels are spoken carefully. Additional cues, probably involving the visibility of the teeth and tongue tip appear to be required for accurate identification.

Some biomechanical correlates of jaw movements

The relative contributions of jaw mass and supporting muscle system stiffness to jaw movements were studied to a first approximation. The amplitude-frequency characteristics of jaw movements were measured in both the normal state and under conditions of increased mass (externally applied weights) and stiffness (spring loading). Vertical jaw movements were produced and controlled by muscle stimulation through wire electrodes implanted directly into the masseter muscle of a single subject. The stimulation signal (2-ms pulse width, 200 pps) was modulated through a function generator to produce oscillatory jaw movements varying from 1 to 15 Hz. Jaw movement was tracked in the vertical dimension using a photoelectric sensing device. It was found that increases in both load and stiffness reduced the amplitude-frequency characteristics of the jaw and that the bandwidth of the amplitude-frequency characteristics of the jaw corresponded to the calculated Eigen frequency of the jaw. These findings suggest that the bandwidth of the amplitude-frequency characteristics of the jaw is determined primarily by the mechanical properties of the controlling muscle. The experimental data were also compared to real speech jaw movement data. [Work supported by NIH Research Grant, NS-10424.]

An intra-oral telemetry system for the continuous recording of vertical jaw movement

Continuous measurement of the separation between upper and lower dental arches, the so-called interocclusal distance (IOD), is of interest in dentistry. Criteria for making such measurements by radio telemetry are discussed. It is concluded that a transmitter small enough to fit in a molar tooth gap is necessary in order to minimize interference with normal function; other design factors are related to obtaining adequate frequency stability, on which measurement accuracy depends. A transmitter fulfilling these requirements is described which sensed the instantaneous value of IOD by the frequency change produced when a metallic object (dental filling, gold crown, shorted turn of wire or piece of ferrite) in one dental arch moved relative to the transmitter in the other.