Masticatory movements and EMG activity following electrolytic lesions of the trigeminal motor nucleus in growing guinea pigs

Byrd, Kenneth E.

doi:10.1016/0002-9416(84)90306-3

Cited by 24 publications

(40 citation statements)

References 21 publications

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“…The lateral pterygoid muscle has an intimate relationship with the TMJ and mandibular condyle and will be discussed below. Previous physiological data from the guinea pig (Byrd, 1984) and ongoing research in the rat (Byrd and Stein, unpublished data) suggest that altered biomechanical forces resulting from changed EMG activity patterns in those muscles supplied by lesioned TMNu may account for most of the morphological sequelae documented in this study. It is also possible, however, that changes in actual muscle size may account for the documented skeletal alterations; further research is needed to define the respective roles of muscle size and activity patterns in the determination of skeletal form.…”

Section: Effects Of Unilateral Tmnu Lesionsmentioning

confidence: 76%

“…Experimentalilesioned animals had unilateral electrolytic lesions (1.5 mA, 15 sec) placed in their left-side TMNu in the manner documented by Byrd (1984Byrd ( , 1988a and using a Kopf model 900 stereotaxic unit. After piercing the dura with a 27-gauge, sterile hypodermic needle, a Rhodes NEX-100, concentric, bipolar electrode was slowly lowered while continuously stimulating the TMNu a t 1 pulse per sec at between 2 and 0.1 V. The electrode descended in a vertical axis, usually 1.9 mm to the left and 0.2 mm posterior to stereotaxic earbar zero.…”

Section: Stereotaxic Surgery Proceduresmentioning

confidence: 99%

“…Altered biomechanical forces that directly effect skeletal asymmetries of the craniofacial complex can be produced by lesioning motoneurons within the brainstem (Gardner et al, 1980;Phillips et al, 1982;Byrd, 1984Byrd, ,1988a. This technique essentially obviates the confounding effects of sensory loss, tissue-scarring, and circulatory interruptions due to nerve and muscle resection methods (Johnston, 1976).…”

Section: Introductionmentioning

confidence: 99%

“…Detailed electromyographic and mandibular movement data (as in Byrd, 1984Byrd, , 1988b from lesioned animals in this study are currently being analyzed and will be published elsewhere.…”

Section: Introductionmentioning

confidence: 99%

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Craniofacial alterations following electrolytic lesions of the trigeminal motor nucleus in actively growing rats

et al. 1990

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The objective of this study was to define further the role of the trigeminal motor nucleus (TMNu) in the postnatal ontogeny of the mammalian craniofacial skeleton. To that end, 42 male Sprague-Dawley rats underwent stereotaxic surgery at 40 days of age; 21 received small electrolytic lesions to their left-side TMNu (lesioned group) while 21 had TMNu stimulation with no actual electrolytic lesion produced (sham group). Seven rats from each group were killed at 28, 56, and 84 days postoperative to analyze trigeminal motoneuron (TMNe) count, masticatory muscle weight, and osteological growth vector data. At all three time periods, lesioned animals showed significant differences 1) between the surgery and nonsurgery sides, and 2) from sham animals. However, sham animals also demonstrated significant between-side differences for medial pterygoid muscle weight (56 days), mandibular height (28 and 56 days), and mandibular length data (84 days); these data suggested that even relatively slight damage to TMNe can create morphological changes within the craniofacial complex. Snout deviation in a lesioned rat towards the opposite side from all other lesioned animals was correlated with unique damage to its pontine reticular formation; this suggested that the observed morphological alterations of the craniofacial complex may have been due not only to TMNu damage, but also to changed expressions of the masticatory central pattern generator (CPG). Morphological alterations of the craniofacial skeleton resulting from lesions to the TMNu were likely due to changed neuromuscular activity patterns of the masticatory muscles and their biomechanical effects upon bone.

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Section: Effects Of Unilateral Tmnu Lesionsmentioning

confidence: 76%

Section: Stereotaxic Surgery Proceduresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Detailed electromyographic and mandibular movement data (as in Byrd, 1984Byrd, , 1988b from lesioned animals in this study are currently being analyzed and will be published elsewhere.…”

Section: Introductionmentioning

confidence: 99%

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Craniofacial alterations following electrolytic lesions of the trigeminal motor nucleus in actively growing rats

et al. 1990

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“…Their mandibular movements during mastication were recorded by the optoelectronic mandibular tracking (OMT) technique described in detail previously Byrd and Luschei, 1980;Byrd and Garthwaite, 1981;Byrd, 1981Byrd, , 1984Byrd, , 1988. The 39-day-old rats were trained by positive reinforcement to accept being restrained for OMT data collection purposes.…”

Section: Methodsmentioning

confidence: 99%

Loci and Characteristics of EMG Silent Periods During Masticatory Mandibular Movements in Rats

Byrd

1988

J Dent Res

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Frontal plane mandibular movements and the associated superficial masseter EMG signals of six 39-day-old rats were simultaneously recorded and digitized at a rate of 1 kHz by the optoelectronic method in order to investigate the loci and attributes of masseteric silent periods during mastication of hard (pellets) and soft (slurry) food items. The marked silent periods, defined as cessations of EMG activity during the slow-close (SC) phase of single chewing cycles, were analyzed for their (1) onset and offset durations relative to physiological centric occlusion (PCO), (2) frontal vertical (FV) and frontal horizontal (FH) loci relative to PCO, and (3) FV and FH velocities and accelerations of masticatory mandibular movements in relation to PCO. The start (SSP) and end (ESP) of silent period loci relative to PCO moved superiorly as sequences of pellet mastication progressed. All silent period attributes during slurry consumption were significantly different (p less than or equal to 0.01) from pellet attributes: Slurry SSP and ESP loci were closer to PCO than were pellet loci; durations of silent period loci during pellet mastication were more variable than were slurry durations. FV distance and velocity values for pellets were greater than with pellets. Although FV velocities during both pellet and slurry mastication decreased at ESP relative to SSP values, their FH velocities at ESP actually increased relative to SSP velocities. Loci attributes of EMG silent periods appeared largely dependent on the consistency of the food item being masticated.

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Increased in vivo levels of neurotransmitters to trigeminal motoneurons: Effects on craniofacial bone and TMJ

et al. 2000

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The results of chronic, in vivo delivery of excitatory and inhibitory neurotransmitter substances upon the craniofacial skeleton are of ongoing interest to clinician and basic scientist alike. Our purpose was to document and compare the effects of biodegradable glycine, glutamate, and thyrotropin-releasing hormone (TRH) microspheres upon the craniofacial skeleton and TMJ of actively growing rats. Glycine, glutamate, TRH, and blank microspheres were stereotactically implanted in proximity to motoneurons within the trigeminal motor nucleus in order to test the following null hypotheses: (1) neurotransmitter microspheres implanted near trigeminal motoneurons of growing rats have no significant effect on the craniofacial skeleton and temporomandibular joints of implanted animals, and (2) there are no significant differences between the relative effects of glutamate, TRH (excitatory to trigeminal motoneurons), and glycine (inhibitory to trigeminal motoneurons) implants upon the craniofacial skeleton and temporomandibular joint. Fifty male Sprague-Dawley rats underwent stereotactic neurosurgery at 35 days; five rats each were killed at 14 and 21 days postoperative for data collection and comparison between glycine-, glutamate-, TRH-, blank-microsphere, and sham-surgery rats. Glycine rats had significantly (P < or = 0.05, 0. 01) smaller implant-side cranial dimensions and mandibular condyles, all glycine rats showed increased gracility of implant-side bones, and deviation of their facial skeleton away from the implant-side; this was in contrast to the generally larger implant-side bony structures in both glutamate and TRH rats. The two null hypotheses were both rejected. Due to their inhibitory and excitatory effects upon trigeminal motoneurons, masticatory muscles, and their neuromuscular generation of biomechanical forces that affect bone, the neurotransmitter substances glycine, glutamate, and TRH appear to play an important role in the growth and development of the mammalian craniofacial skeleton and TMJ.

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Masticatory movements and EMG activity following electrolytic lesions of the trigeminal motor nucleus in growing guinea pigs

Cited by 24 publications

References 21 publications

Craniofacial alterations following electrolytic lesions of the trigeminal motor nucleus in actively growing rats

Craniofacial alterations following electrolytic lesions of the trigeminal motor nucleus in actively growing rats

Loci and Characteristics of EMG Silent Periods During Masticatory Mandibular Movements in Rats

Increased in vivo levels of neurotransmitters to trigeminal motoneurons: Effects on craniofacial bone and TMJ

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