1
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Nakatomi C, Hsu CC, Ono K. Correlations of sensations of hardness and springiness of agar and gelatin gels with mechanical properties in human participants. J Oral Biosci 2023; 65:316-323. [PMID: 37689308 DOI: 10.1016/j.job.2023.09.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 08/31/2023] [Accepted: 09/02/2023] [Indexed: 09/11/2023]
Abstract
OBJECTIVES It is unclear which mechanical properties of foods cause the texture sensation in humans. This study aimed to investigate the relationship between unilateral compression measurements and the sensations of hardness and springiness in gels. METHODS Three different concentrations of agar and gelatin gels were prepared by the addition of agar (1%, 2%, and 3%) and gelatin (4%, 8%, and 16%) to water or apple juice. In a stress-rupture test, stress-strain curves were obtained by the application of uniaxial compression with a disc plunger at a compression rate of 10 mm/s. The hardness, springiness, and palatability of the gels were evaluated by 12 healthy volunteers using a visual analog scale. RESULTS The sensation of hardness was positively correlated with the sensation of springiness for the agar and gelatin gels. Palatability decreased as hardness increased for both gels. In terms of mechanical properties, the sensation of hardness was only significantly correlated with the initial elastic modulus, while the sensation of springiness was correlated with the late elastic modulus and other mechanical properties such as fracture strain, time, and stress. CONCLUSIONS These results suggest that sensations of hardness and springiness are produced in the initial and late stages, respectively, during the food-crushing process using the tongue, palate, and teeth.
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Affiliation(s)
- Chihiro Nakatomi
- Division of Physiology, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, Fukuoka 803-8580, Japan.
| | - Chia-Chien Hsu
- Division of Physiology, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, Fukuoka 803-8580, Japan
| | - Kentaro Ono
- Division of Physiology, Kyushu Dental University, 2-6-1 Manazuru, Kokurakita-ku, Kitakyushu, Fukuoka 803-8580, Japan
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2
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Kochi I, Takei E, Maeda R, Ito K, Magara J, Tsujimura T, Kulvanich S, Inoue M. Changes of bolus properties and the triggering of swallowing in healthy humans. J Oral Rehabil 2021; 48:592-600. [PMID: 33481324 DOI: 10.1111/joor.13151] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 01/14/2021] [Indexed: 11/26/2022]
Abstract
There is wide variation in chewing behaviours, even among healthy humans. Further, the way in which humans determine swallowing initiation when chewing solid foods remains unclear. The current study sought to investigate how the bolus properties change over time during chewing, and to clarify which factors affect chewing and swallowing behaviours, including swallowing initiation, in healthy humans. Twenty-four healthy volunteers were instructed to chew 8 g of steamed rice and spit it out at 50%, 100% and 150% of their own chewing duration, defined as the time of chewing from onset of the first chewing cycle to onset of the first swallow. Chewing and swallowing behaviours were monitored and determined by visual inspection of video recordings. The physical properties such as hardness, cohesiveness and adhesiveness as well as water content of the bolus were measured. In each subject, maximum bite force, tongue pressure and stimulated salivary flow rate were also measured. Hardness gradually decreased, and the cohesiveness and water content of the bolus did not change up to 50% of chewing duration, followed by a slight but significant increase. The adhesiveness of the bolus rapidly decreased at the beginning of chewing. Chewing duration was significantly related to stimulated salivary flow rate; greater salivary flow rate was associated with shorter chewing duration. Variation of chewing duration and swallowing initiation was not dependent on bolus properties during the chewing of steamed rice, but mainly depended on the surface lubrication of the bolus.
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Affiliation(s)
- Izumi Kochi
- Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Eri Takei
- Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Rumiko Maeda
- Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.,Department of Rehabilitation, Faculty of Health Science, Kansai University of Welfare Sciences, Osaka, Japan
| | - Kayoko Ito
- Oral Rehabilitation, Niigata University Medical and Dental Hospital, Niigata, Japan
| | - Jin Magara
- Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Takanori Tsujimura
- Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Sirima Kulvanich
- Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Makoto Inoue
- Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
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3
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de Oliveira JC, Sordi MB, da Cruz ACC, Zanetti RV, Betiol EAG, Vieira SR, Zanetti AL. Number of dental abutments influencing the biomechanical behavior of tooth‒implant-supported fixed partial dentures: A finite element analysis. J Dent Res Dent Clin Dent Prospects 2020; 14:228-234. [PMID: 33575012 PMCID: PMC7867679 DOI: 10.34172/joddd.2020.047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 10/21/2020] [Indexed: 11/09/2022] Open
Abstract
Background. Local or systemic issues might prevent installing a sufficient number of dental implants for fixed prosthetic rehabilitation. Splinting dental implants and natural teeth in fixed dentures could overcome such limitations. Therefore, this study aimed to evaluate the influence of the number of dental abutments in the biomechanics of tooth‒implant-supported fixed partial dentures (FPDs). The null hypothesis was that increasing the number of abutment teeth would not decrease the stress over the abutments and surrounding bone. Methods. Left mandibular lateral incisor, canine, premolars, and molars were reconstructed through computed tomography and edited using image processing software to represent a cemented fixed metal‒ceramic partial denture. Three models were set to reduce the number of abutment teeth: 1) lateral incisor, canine, and first premolar; 2) canine and first premolar; 3) the first premolar. The second premolar and first molar were set as pontics, and the second molar was set as an implant abutment in all the models. Finite element analyses were performed under physiologic masticatory forces with axial and oblique loading vectors. Results. After simulation of axial loads, the stress peaks on the bone around the implant, the bone around the first premolar, and prosthetic structures did not exhibit significant changes when the number of abutment teeth decreased. However, under oblique loads, decreasing the number of abutment teeth increased stress peaks on the surrounding bone and denture. Conclusion. Increasing the number of dental abutments in tooth‒implant-supported cemented FPD models decreased stresses on its constituents, favoring the prosthetic biomechanics.
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Affiliation(s)
| | - Mariane Beatriz Sordi
- Postgraduate in Dentistry, Federal University of Santa Catarina, Florianópolis, Brazil
| | | | | | | | | | - Artêmio Luiz Zanetti
- Department of Prosthodontics, Faculty of Dentistry, University of São Paulo, São Paulo, Brazil
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4
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Sato F, Kado S, Tsutsumi Y, Tachibana Y, Ikenoue E, Furuta T, Uchino K, Bae YC, Uzawa N, Yoshida A. Ascending projection of jaw-closing muscle-proprioception to the intralaminar thalamic nuclei in rats. Brain Res 2020; 1739:146830. [PMID: 32278724 DOI: 10.1016/j.brainres.2020.146830] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 04/06/2020] [Accepted: 04/07/2020] [Indexed: 12/29/2022]
Abstract
An invasive intralaminar thalamic stimulation and a non-invasive application of oral splint are both effective in treating tic symptoms of patients with Tourette syndrome (TS). Therefore, these two treatments may exert some influence on the same brain region in TS patients. We thus hypothesized that the proprioceptive input arising from the muscle spindles of jaw-closing muscles (JCMSs), known to be increased by the application of oral splint, is transmitted to the intralaminar thalamic nuclei. To test this issue, we morphologically and electrophysiologically examined the thalamic projections of proprioceptive input from the JCMSs to the intralaminar thalamic nuclei of rats. We first injected an anterograde tracer, biotinylated dextranamine, into the electrophysiologically identified supratrigeminal nucleus, which is known to receive proprioceptive inputs from the JCMSs via the trigeminal mesencephalic neurons. A moderate number of biotinylated dextranamine-labeled axon terminals were bilaterally distributed in the oval paracentral nucleus (OPC) of the intralaminar thalamic nuclei. We also detected electrophysiological responses to the electrical stimulation of bilateral masseter nerves and to sustained jaw-opening in the OPC. After injection of retrograde tracer (cholera toxin B subunit or Fluorogold) into the OPC, neuronal cell bodies were retrogradely labeled in the rostrodorsal portion of the bilateral supratrigeminal nucleus. Here, we show that proprioceptive inputs from the JCMSs are conveyed to the OPC in the intralaminar nuclei via the supratrigeminal nucleus. This study can help to understand previously unrecognized pathways of proprioception ascending inputs from the brainstem to the thalamus, which may contribute to treatments of TS patients.
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Affiliation(s)
- Fumihiko Sato
- Department of Oral Anatomy and Neurobiology, Graduate School of Dentistry, Osaka University, Suita, Osaka 565-0871, Japan
| | - Seiya Kado
- Department of Oral Anatomy and Neurobiology, Graduate School of Dentistry, Osaka University, Suita, Osaka 565-0871, Japan; Department of Oral and Maxillofacial Surgery 2, Graduate School of Dentistry, Osaka University, Suita, Osaka 565-0871, Japan
| | - Yumi Tsutsumi
- Department of Oral Anatomy and Neurobiology, Graduate School of Dentistry, Osaka University, Suita, Osaka 565-0871, Japan
| | - Yoshihisa Tachibana
- Division of System Neuroscience, Kobe University Graduate School of Medicine, Kobe, Hyogo 650-0017, Japan
| | - Etsuko Ikenoue
- Department of Oral Anatomy and Neurobiology, Graduate School of Dentistry, Osaka University, Suita, Osaka 565-0871, Japan
| | - Takahiro Furuta
- Department of Oral Anatomy and Neurobiology, Graduate School of Dentistry, Osaka University, Suita, Osaka 565-0871, Japan
| | - Katsuro Uchino
- Department of Oral Anatomy and Neurobiology, Graduate School of Dentistry, Osaka University, Suita, Osaka 565-0871, Japan; Department of Acupuncture, Takarazuka University of Medical and Health Care, Takarazuka, Hyogo 666-0162, Japan
| | - Yong Chul Bae
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu 700-412, Republic of Korea
| | - Narikazu Uzawa
- Department of Oral and Maxillofacial Surgery 2, Graduate School of Dentistry, Osaka University, Suita, Osaka 565-0871, Japan
| | - Atsushi Yoshida
- Department of Oral Anatomy and Neurobiology, Graduate School of Dentistry, Osaka University, Suita, Osaka 565-0871, Japan.
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5
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Narita N, Ishii T, Iwaki S, Kamiya K, Okubo M, Uchida T, Kantake I, Shibutani K. Prefrontal Consolidation and Compensation as a Function of Wearing Denture in Partially Edentulous Elderly Patients. Front Aging Neurosci 2020; 11:375. [PMID: 32082135 PMCID: PMC7005254 DOI: 10.3389/fnagi.2019.00375] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 12/23/2019] [Indexed: 12/11/2022] Open
Abstract
Background The cognitive effects of wearing a denture are not well understood. This study was conducted to clarify the effects of denture use on prefrontal and chewing muscle activities, occlusal state, and subjective chewing ability in partially edentulous elderly individuals. Methods A total of 16 partially edentulous patients were enrolled. Chewing-related prefrontal cortex and jaw muscle activities were simultaneously examined using a functional near-infrared spectroscopy (fNIRS) device and electromyography, under the conditions of unwearing, and wearing a denture. Occlusal state and masticatory score were also determined under both conditions. Using multiple linear regression analysis, associations between prefrontal and chewing activities with wearing were examined using change rates. Results Chewing rhythmicity was maintained under both conditions. As compared with unwearing, the wearing condition was associated with improved prefrontal cortex and chewing muscle activities, occlusal state in regard to force and area, and masticatory score. Also, prefrontal activities were positively associated with burst duration and peak amplitude in masseter (Mm) and temporal muscle activities, as well as masticatory scores. In contrast, prefrontal activities were negatively associated with occlusal force. Conclusion Wearing a denture induced a positive association between burst duration and peak amplitude in Mm and temporal muscle activities and prefrontal activity, which may indicate a parallel consolidation of prefrontal cortex and rhythmical chewing activities, as well as masticatory scores. On the other hand, denture use induced a negative association of occlusal force with prefrontal activities, which might suggest that prefrontal compensative associations for the physiocognitive acquisition depended on biomechanical efficacy gained by wearing a denture.
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Affiliation(s)
- Noriyuki Narita
- Research Institute of Oral Science, Nihon University School of Dentistry at Matsudo, Matsudo, Japan
| | - Tomohiro Ishii
- Department of Removable Prosthodontics, Nihon University School of Dentistry at Matsudo, Matsudo, Japan
| | - Sunao Iwaki
- Automotive Human Factors Research Center, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan
| | - Kazunobu Kamiya
- Department of Removable Prosthodontics, Nihon University School of Dentistry at Matsudo, Matsudo, Japan
| | - Masakazu Okubo
- Department of Removable Prosthodontics, Nihon University School of Dentistry at Matsudo, Matsudo, Japan
| | | | - Ikuo Kantake
- Dental Support Co. Ltd., Chiba, Japan.,Department of Anesthesiology, Nihon University School of Dentistry at Matsudo, Matsudo, Japan
| | - Koh Shibutani
- Department of Anesthesiology, Nihon University School of Dentistry at Matsudo, Matsudo, Japan
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6
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Maeda-Iino A, Fukushima M, Sakoguchi Y, Omure H, Oishi A, Oga Y, Furukawa-Sainoki M, Kanmura S, Ido A, Miyawaki S. Effects of intra-oesophageal acid infusion and a stress task on masseter muscle activity and autonomic nervous activity in wakefulness. J Oral Rehabil 2020; 47:567-576. [PMID: 32064657 DOI: 10.1111/joor.12947] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 01/27/2020] [Accepted: 02/09/2020] [Indexed: 11/30/2022]
Abstract
BACKGROUND Gastroesophageal reflux disease may be an important risk factor for awake bruxism. Additionally, it has been known that a psychological stress task affects masseter muscle activity, and autonomic nervous system (ANS) activity modulation induces masseter muscle activity. OBJECTIVES This study aimed to investigate whether task-induced stress and experimental oesophageal acid infusion increase masseter muscle activity and alter ANS activity, compared to rest task and oesophageal saline infusion, respectively. METHODS Polygraphic monitoring, consisting of electromyography of the masseter muscle and electrocardiography, was performed in 12 healthy adult men during 30-min interventions with intra-oesophageal saline or acid infusion, while reading a book quietly, as rest, and while performing calculation, as a stress task. RESULTS At rest, masseter muscle activity and parasympathetic nervous system (PNS) activity during acid infusion were significantly higher (P = .019) and lower (P = .021) than during saline infusion, respectively. During saline infusion, both masseter muscle activity and sympathetic nervous system (SNS) activity or PNS activity while performing the calculation task were higher (P = .022 and .012, respectively) or lower (P = .007) than those during the reading task, respectively. In two-way repeated-measures ANOVA, intra-oesophageal infusion (saline or acid) significantly affected masseter muscle activity (P = .008) and PNS activity (P = .021). However, performing tasks (reading or calculation) significantly affected only PNS activity (P = .028). CONCLUSION Intra-oesophageal acid infusion significantly increased masseter muscle activity and decreased PNS activity. In contrast, stress task not only significantly decreased PNS activity, but only modestly increased masseter muscle activity and SNS activity.
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Affiliation(s)
- Aya Maeda-Iino
- Field of Developmental Medicine, Health Research Course, Department of Orthodontics and Dentofacial Orthopedics, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Mika Fukushima
- Field of Developmental Medicine, Health Research Course, Department of Orthodontics and Dentofacial Orthopedics, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Yoko Sakoguchi
- Field of Developmental Medicine, Health Research Course, Department of Orthodontics and Dentofacial Orthopedics, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.,Sakoguchi Dental Clinic, Kagoshima, Japan
| | - Haruhito Omure
- Field of Developmental Medicine, Health Research Course, Department of Orthodontics and Dentofacial Orthopedics, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.,Omure Orthodontic Clinic, Matsuyama, Japan
| | - Akihito Oishi
- Field of Developmental Medicine, Health Research Course, Department of Orthodontics and Dentofacial Orthopedics, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Yasuhiko Oga
- Field of Developmental Medicine, Health Research Course, Department of Orthodontics and Dentofacial Orthopedics, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Minami Furukawa-Sainoki
- Field of Developmental Medicine, Health Research Course, Department of Orthodontics and Dentofacial Orthopedics, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Shuji Kanmura
- Department of Endoscopy, Kagoshima University Hospital, Kagoshima, Japan
| | - Akio Ido
- Digestive and Lifestyle Diseases, Department of Human and Environmental Sciences, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Shouichi Miyawaki
- Field of Developmental Medicine, Health Research Course, Department of Orthodontics and Dentofacial Orthopedics, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.,Faculty of Dental Medicine, Airlangga University, Surabaya, Indonesia
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7
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Prefrontal cortex activity induced by periodontal afferent inputs downregulates occlusal force. Exp Brain Res 2019; 237:2767-2774. [DOI: 10.1007/s00221-019-05630-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 08/14/2019] [Indexed: 10/26/2022]
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8
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Nagata A, Nakayama K, Nakamura S, Mochizuki A, Gemba C, Aoki R, Dantsuji M, Maki K, Inoue T. Serotonin1B receptor-mediated presynaptic inhibition of proprioceptive sensory inputs to jaw-closing motoneurons. Brain Res Bull 2019; 149:260-267. [DOI: 10.1016/j.brainresbull.2019.05.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Revised: 04/26/2019] [Accepted: 05/02/2019] [Indexed: 10/26/2022]
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9
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Fukutake M, Ikebe K, Okubo H, Matsuda KI, Enoki K, Inomata C, Takeshita H, Mihara Y, Hatta K, Gondo Y, Kamide K, Masui Y, Ishizaki T, Arai Y, Maeda Y. Relationship between oral stereognostic ability and dietary intake in older Japanese adults with complete dentures. J Prosthodont Res 2018; 63:105-109. [PMID: 30385332 DOI: 10.1016/j.jpor.2018.10.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 09/14/2018] [Accepted: 10/07/2018] [Indexed: 11/15/2022]
Abstract
PURPOSE Oral stereognostic ability (OSA) is a useful indicator of oral perception to recognize food characteristics during mastication. Previous studies have shown associations between dietary intake and oral health status, such as taste perception. However, the effect of oral sensory ability on dietary intake is unclear. The purpose of this study was to investigate the association between oral sensory ability and dietary intake in older Japanese complete denture wearers. METHODS This cross-sectional study included 164 participants aged 69-71 or 79-81years old, wearing both maxillary and mandibular complete dentures. OSA test was used to evaluate oral tactile perception. Diet during the preceding month was assessed using a self-administered diet history questionnaire. Multivariable linear regression analysis was conducted to assess the association between OSA score and food and nutrient intake after adjusting for age, sex, socioeconomic factors, and occlusal force. RESULTS The bivariate analysis showed that OSA score was significantly and positively correlated with intake of green and yellow vegetables and negatively correlated with intake of cereals among examined foods. OSA score was also positively correlated with intake of vitamins A, B2, and C and α-tocopherol (as a substitute for vitamin E) among examined nutrients. After adjusting for age, sex, socioeconomic factors, and occlusal force, OSA score remained significantly associated with intake of green and yellow vegetables and α-tocopherol. CONCLUSIONS OSA was significantly associated with intake of green and yellow vegetables in older complete denture wearers.
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Affiliation(s)
- Motoyoshi Fukutake
- Department of Prosthodontics, Gerodontology and Oral Rehabilitation, Osaka University Graduate School of Dentistry, Suita, Japan.
| | - Kazunori Ikebe
- Department of Prosthodontics, Gerodontology and Oral Rehabilitation, Osaka University Graduate School of Dentistry, Suita, Japan
| | - Hitomi Okubo
- Department of Health Promotion, National Institute of Publish Health, Wako, Japan
| | - Ken-Ichi Matsuda
- Department of Prosthodontics, Gerodontology and Oral Rehabilitation, Osaka University Graduate School of Dentistry, Suita, Japan
| | - Kaori Enoki
- Department of Prosthodontics, Gerodontology and Oral Rehabilitation, Osaka University Graduate School of Dentistry, Suita, Japan
| | - Chisato Inomata
- Department of Prosthodontics, Gerodontology and Oral Rehabilitation, Osaka University Graduate School of Dentistry, Suita, Japan
| | - Hajime Takeshita
- Department of Prosthodontics, Gerodontology and Oral Rehabilitation, Osaka University Graduate School of Dentistry, Suita, Japan
| | - Yusuke Mihara
- Department of Prosthodontics, Gerodontology and Oral Rehabilitation, Osaka University Graduate School of Dentistry, Suita, Japan
| | - Kodai Hatta
- Department of Prosthodontics, Gerodontology and Oral Rehabilitation, Osaka University Graduate School of Dentistry, Suita, Japan
| | - Yasuyuki Gondo
- Department of Clinical Thanatology and Geriatric Behavioral Science, Osaka University Graduate School of Human Sciences, Suita, Japan
| | - Kei Kamide
- Department of Geriatric Medicine and Nephrology, Osaka University Graduate School of Medicine, Suita, Japan
| | - Yukie Masui
- Tokyo Metropolitan Geriatric Hospital and Institute of Gerontology, Itabashi, Japan
| | - Tatsuro Ishizaki
- Tokyo Metropolitan Geriatric Hospital and Institute of Gerontology, Itabashi, Japan
| | - Yasumichi Arai
- Division of Geriatric Medicine, Department of Internal Medicine, Keio University School of Medicine, Shinjuku, Japan
| | - Yoshinobu Maeda
- Department of Prosthodontics, Gerodontology and Oral Rehabilitation, Osaka University Graduate School of Dentistry, Suita, Japan
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10
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Laird MF. Variation in human gape cycle kinematics and occlusal topography. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2017; 164:574-585. [DOI: 10.1002/ajpa.23298] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 07/07/2017] [Accepted: 08/01/2017] [Indexed: 11/08/2022]
Affiliation(s)
- Myra F. Laird
- Department of Organismal Biology and Anatomy; University of Chicago; Chicago Illinois 60637
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11
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Tanaka M, Bruno C, Jacobs R, Torisu T, Murata H. Short-term follow-up of masticatory adaptation after rehabilitation with an immediately loaded implant-supported prosthesis: a pilot assessment. Int J Implant Dent 2017; 3:8. [PMID: 28271438 PMCID: PMC5340790 DOI: 10.1186/s40729-017-0070-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 02/23/2017] [Indexed: 12/14/2022] Open
Abstract
Background When teeth are extracted, sensory function is decreased by a loss of periodontal ligament receptions. When replacing teeth by oral implants, one hopes to restore the sensory feedback pathway as such to allow for physiological implant integration and optimized oral function with implant-supported prostheses. What remains to be investigated is how to adapt to different oral rehabilitations. The purpose of this pilot study was to assess four aspects of masticatory adaptation after rehabilitation with an immediately loaded implant-supported prosthesis and to observe how each aspect will recover respectively. Methods Eight participants with complete dentures were enrolled. They received an implant-supported acrylic resin provisional bridge, 1 day after implant surgery. Masticatory adaptation was examined by assessing occlusal contact, approximate maximum bite force, masticatory efficiency of gum-like specimens, and food hardness perception. Results Occlusal contact and approximate maximum bite force were significantly increased 3 months after implant rehabilitation, with the bite force gradually building up to a 72% increase compared to baseline. Masticatory efficiency increased by 46% immediately after surgery, stabilizing at around 40% 3 months after implant rehabilitation. Hardness perception also improved, with a reduction of the error rate by 16% over time. Conclusions This assessment demonstrated masticatory adaptation immediately after implant rehabilitation with improvements noted up to 3 months after surgery and rehabilitation. It was also observed that, despite gradually improved bite force in all patients, masticatory efficiency and food hardness perception did not necessarily follow this tendency. The findings in this pilot may also be used to assess adaptation of oral function after implant rehabilitation by studying the combined outcome of four tests (occlusal contact, maximum bite force, masticatory efficiency, and food hardness perception).
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Affiliation(s)
- Mihoko Tanaka
- Department of Prosthetic Dentistry, Graduate School of Biomedical Science, Nagasaki University, 1-7-1 Sakamoto, Nagasaki, 852-8588, Japan. .,Centre for Periodontology and Implantology Leuven, IJzerenmolenstraat 110, B-3001, Heverlee, Belgium.
| | - Collaert Bruno
- Centre for Periodontology and Implantology Leuven, IJzerenmolenstraat 110, B-3001, Heverlee, Belgium
| | - Reinhilde Jacobs
- OMFS IMPATH, Department of Imaging & Pathology, University of Leuven, Kapucijnenvoer 33, BE-3000, Leuven, Belgium.,Oral and Maxillofacial Surgery, University Hospitals Leuven, Kapucijnenvoer 33, BE-3000, Leuven, Belgium
| | - Tetsurou Torisu
- Department of Prosthetic Dentistry, Graduate School of Biomedical Science, Nagasaki University, 1-7-1 Sakamoto, Nagasaki, 852-8588, Japan
| | - Hiroshi Murata
- Department of Prosthetic Dentistry, Graduate School of Biomedical Science, Nagasaki University, 1-7-1 Sakamoto, Nagasaki, 852-8588, Japan
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12
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Effects of chronic exposure to low dose THIP on brainstem neuronal excitability in mouse models of Rett syndrome: Evidence from symptomatic females. Neuropharmacology 2017; 116:288-299. [PMID: 28069353 DOI: 10.1016/j.neuropharm.2017.01.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2016] [Revised: 12/10/2016] [Accepted: 01/04/2017] [Indexed: 01/17/2023]
Abstract
Rett Syndrome (RTT) is a neurodevelopmental disorder caused by mutations of the MECP2 gene, affecting predominantly females. One of the characteristic features of the disease is defective brainstem autonomic function. In Mecp2-/Y mice, several groups of brainstem neurons are overly excitable, which causes destabilization of neuronal networks for the autonomic control. We have previously shown that the extrasynaptic GABAA receptor agonist THIP relieves many RTT-like symptoms in Mecp2-/Y mice. Although neuronal activity is inhibited by acute THIP exposure, how a chronic treatment affects neuronal excitability remains elusive. Thus, we performed studies to address whether increased excitability occurs in brainstem neurons of female Mecp2+/- mice, how the MeCP expression affects the neuronal excitability, and whether chronic THIP exposure improves the neuronal hyperexcitability. Symptomatic Mecp2+/- (sMecp2+/-) female mice were identified with a two-step screening system. Whole-cell recording was performed in brain slices after a prior exposure of the sMecp2+/- mice to a 5-week low-dose THIP. Neurons in the locus coeruleus (LC) and the mesencephalic trigeminal nucleus (Me5) showed excessive firing activity in the sMecp2+/- mice. THIP pretreatment reduced the hyperexcitability of both LC and Me5 neurons in the sMecp2+/- mice, to a similar level as their counterparts in Mecp2-/Y mice. In identified LC neurons, the hyperexcitability appeared to be determined by not only the MeCP2 expression, but also their environmental cues. The alleviation of LC neuronal hyperexcitability seems to benefit brainstem autonomic function as THIP also improved breathing abnormalities of these sMecp2+/- mice.
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Oginsky MF, Cui N, Zhong W, Johnson CM, Jiang C. Hyperexcitability of Mesencephalic Trigeminal Neurons and Reorganization of Ion Channel Expression in a Rett Syndrome Model. J Cell Physiol 2016; 232:1151-1164. [PMID: 27670841 DOI: 10.1002/jcp.25589] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 09/06/2016] [Indexed: 12/30/2022]
Abstract
People with Rett syndrome (RTT) have defects in motor function also seen in Mecp2-null mice. Motor function depends on not only central motor commands but also sensory feedback that is vulnerable to changes in excitability of propriosensory neurons. Here we report evidence for hyperexcitability of mesencephalic trigeminal (Me5) neurons in Mecp2-null mice and a novel cellular mechanism for lowering its impact. In in vitro brain slices, the Me5 neurons in both Mecp2-/Y male and symptomatic Mecp2+/- female mice were overly excitable showing increased firing activity in comparison to their wild-type (WT) male and asymptomatic counterparts. In Mecp2-/Y males, Me5 neurons showed a reduced firing threshold. Consistently, the steady-state activation of voltage-gated Na+ currents (INa ) displayed a hyperpolarizing shift in the Mecp2-null neurons with no change in the INa density. This seems to be due to NaV1.1, SCN1B and SCN4B overexpression and NaV1.2 and SCN3B under-expression. In contrast to the hyperexcitability, the sag potential and postinhibitory rebound (PIR) were reduced in Mecp2-null mice. In voltage-clamp, the IH density was deficient by ∼33%, and the steady-state half-activation had a depolarizing shift of ∼10 mV in the Mecp2-null mice. Quantitative PCR analysis indicated that HCN2 was decreased, HCN1 was upregulated with no change in HCN4 in Mecp2-/Y mice compared to WT. Lastly, blocking IH reduced the firing rate much more in WT than in Mecp2-null neurons. These data suggest that the Mecp2 defect causes an increase in Me5 neuronal excitability likely attributable to alterations in INa , meanwhile IH is reduced likely altering neuronal excitability as well. J. Cell. Physiol. 232: 1151-1164, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Max F Oginsky
- Department of Biology, Georgia State University, Atlanta, Georgia
| | - Ningren Cui
- Department of Biology, Georgia State University, Atlanta, Georgia
| | - Weiwei Zhong
- Department of Biology, Georgia State University, Atlanta, Georgia
| | | | - Chun Jiang
- Department of Biology, Georgia State University, Atlanta, Georgia
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Gemba C, Nakayama K, Nakamura S, Mochizuki A, Inoue M, Inoue T. Involvement of histaminergic inputs in the jaw-closing reflex arc. J Neurophysiol 2015; 113:3720-35. [PMID: 25904711 DOI: 10.1152/jn.00515.2014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 04/20/2015] [Indexed: 11/22/2022] Open
Abstract
Histamine receptors are densely expressed in the mesencephalic trigeminal nucleus (MesV) and trigeminal motor nucleus. However, little is known about the functional roles of neuronal histamine in controlling oral-motor activity. Thus, using the whole-cell recording technique in brainstem slice preparations from Wistar rats aged between postnatal days 7 and 13, we investigated the effects of histamine on the MesV neurons innervating the masseter muscle spindles and masseter motoneurons (MMNs) that form a reflex arc for the jaw-closing reflex. Bath application of histamine (100 μM) induced membrane depolarization in both MesV neurons and MMNs in the presence of tetrodotoxin, whereas histamine decreased and increased the input resistance in MesV neurons and MMNs, respectively. The effects of histamine on MesV neurons and MMNs were mimicked by an H1 receptor agonist, 2-pyridylethylamine (100 μM). The effects of an H2 receptor agonist, dimaprit (100 μM), on MesV neurons were inconsistent, whereas MMNs were depolarized without changes in the input resistance. An H3 receptor agonist, immethridine (100 μM), also depolarized both MesV neurons and MMNs without changing the input resistance. Histamine reduced the peak amplitude of postsynaptic currents (PSCs) in MMNs evoked by stimulation of the trigeminal motor nerve (5N), which was mimicked by 2-pyridylethylamine but not by dimaprit or immethridine. Moreover, 2-pyridylethylamine increased the failure rate of PSCs evoked by minimal stimulation and the paired-pulse ratio. These results suggest that histaminergic inputs to MesV neurons through H1 receptors are involved in the suppression of the jaw-closing reflex although histamine depolarizes MesV neurons and/or MMNs.
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Affiliation(s)
- Chikako Gemba
- Department of Oral Physiology, Showa University School of Dentistry, Shinagawa-ku, Tokyo, Japan; Department of Pediatric Dentistry, Showa University School of Dentistry, Oota-ku, Tokyo, Japan
| | - Kiyomi Nakayama
- Department of Oral Physiology, Showa University School of Dentistry, Shinagawa-ku, Tokyo, Japan
| | - Shiro Nakamura
- Department of Oral Physiology, Showa University School of Dentistry, Shinagawa-ku, Tokyo, Japan
| | - Ayako Mochizuki
- Department of Oral Physiology, Showa University School of Dentistry, Shinagawa-ku, Tokyo, Japan
| | - Mitsuko Inoue
- Department of Pediatric Dentistry, Showa University School of Dentistry, Oota-ku, Tokyo, Japan
| | - Tomio Inoue
- Department of Oral Physiology, Showa University School of Dentistry, Shinagawa-ku, Tokyo, Japan
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Chung G, Saito M, Kawasaki Y, Kawano T, Yin D, Lee S, Kogo M, Takada M, Bae YC, Kim JS, Oh SB, Kang Y. Generation of resonance-dependent oscillation by mGluR-I activation switches single spiking to bursting in mesencephalic trigeminal sensory neurons. Eur J Neurosci 2015; 41:998-1012. [PMID: 25712773 DOI: 10.1111/ejn.12858] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 01/19/2015] [Accepted: 01/26/2015] [Indexed: 11/29/2022]
Abstract
The primary sensory neurons supplying muscle spindles of jaw-closing muscles are unique in that they have their somata in the mesencephalic trigeminal nucleus (MTN) in the brainstem, thereby receiving various synaptic inputs. MTN neurons display bursting upon activation of glutamatergic synaptic inputs while they faithfully relay respective impulses arising from peripheral sensory organs. The persistent sodium current (IN aP ) is reported to be responsible for both the generation of bursts and the relay of impulses. We addressed how IN aP is controlled either to trigger bursts or to relay respective impulses as single spikes in MTN neurons. Protein kinase C (PKC) activation enhanced IN aP only at low voltages. Spike generation was facilitated by PKC activation at membrane potentials more depolarized than the resting potential. By injection of a ramp current pulse, a burst of spikes was triggered from a depolarized membrane potential whereas its instantaneous spike frequency remained almost constant despite the ramp increases in the current intensity beyond the threshold. A puff application of glutamate preceding the ramp pulse lowered the threshold for evoking bursts by ramp pulses while chelerythrine abolished such effects of glutamate. Dihydroxyphenylglycine, an agonist of mGluR1/5, also caused similar effects, and increased both the frequency and impedance of membrane resonance. Immunohistochemistry revealed that glutamatergic synapses are made onto the stem axons, and that mGluR1/5 and Nav1.6 are co-localized in the stem axon. Taken together, glutamatergic synaptic inputs onto the stem axon may be able to switch the relaying to the bursting mode.
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Affiliation(s)
- Gehoon Chung
- Department of Neuroscience and Oral Physiology, Osaka University Graduate School of Dentistry, Suita, Osaka, 565-0871, Japan; Pain Cognitive Function Research Center, Dental Research Institute and Department of Neurobiology and Physiology, School of Dentistry, Seoul National University, Seoul, Korea
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New directions for understanding neural control in swallowing: the potential and promise of motor learning. Dysphagia 2012. [PMID: 23192633 DOI: 10.1007/s00455-012-9432-y] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Oropharyngeal swallowing is a complex sensorimotor phenomenon that has had decades of research dedicated to understanding it more thoroughly. However, the underlying neural mechanisms responsible for normal and disordered swallowing remain very vague. We consider this gap in knowledge the result of swallowing research that has been broad (identifying phenomena) but not deep (identifying what controls the phenomena). The goals of this review are to address the complexity of motor control of oropharyngeal swallowing and to review the principles of motor learning based on limb movements as a model system. We compare this literature on limb motor learning to what is known about oropharyngeal function as a first step toward suggesting the use of motor learning principles in swallowing research.
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Tsukiboshi T, Sato H, Tanaka Y, Saito M, Toyoda H, Morimoto T, Türker KS, Maeda Y, Kang Y. Illusion caused by vibration of muscle spindles reveals an involvement of muscle spindle inputs in regulating isometric contraction of masseter muscles. J Neurophysiol 2012; 108:2524-33. [PMID: 22914653 DOI: 10.1152/jn.00997.2011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
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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Affiliation(s)
- Taisuke Tsukiboshi
- Department of Neuroscience and Oral Physiology, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan
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Response properties of temporomandibular joint mechanosensitive neurons in the trigeminal sensory complex of the rabbit. Exp Brain Res 2012; 222:113-23. [PMID: 22855309 DOI: 10.1007/s00221-012-3200-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Accepted: 07/20/2012] [Indexed: 10/28/2022]
Abstract
The neurophysiological properties of neurons sensitive to TMJ movement (TMJ neurons) in the trigeminal sensory complex (Vcomp) during passive movement of the isolated condyle were examined in 46 rabbits. Discharges of TMJ neurons from the rostral part of the Vcomp were recorded with a microelectrode when the isolated condyle was moved manually and with a computer-regulated mechanostimulator. A total of 443 neurons responding to mechanical stimulation of the face and oral cavity were recorded from the brainstem. Twenty-one TMJ neurons were detected rostrocaudally from the dorsal part of the trigeminal principal sensory nucleus (NVsnpr), subnucleus oralis of the trigeminal spinal nucleus, and reticular formation surrounding the trigeminal motor nucleus. Most of the TMJ neurons were located in the dorso-rostral part of the NVsnpr. Of the TMJ units recorded, 90 % were slowly adapting and 26 % had an accompanying resting discharge. The majority (86 %) of the TMJ units responded to the movement of the isolated condyle in the anterior and/or ventral directions, and half were sensitive to the condyle movement in a single direction. The discharge frequencies of TMJ units increased as the condyle displacement and constant velocity (5 mm/s) increased within a 5-mm anterior displacement of the isolated condyle. Based on these results, we conclude that sensory information is processed by TMJ neurons encoding at least joint position and displacement in the physiological range of mandibular displacement.
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Panagiotopoulou O, Kupczik K, Cobb SN. The mechanical function of the periodontal ligament in the macaque mandible: a validation and sensitivity study using finite element analysis. J Anat 2011; 218:75-86. [PMID: 20584094 DOI: 10.1111/j.1469-7580.2010.01257.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Whilst the periodontal ligament (PDL) acts as an attachment tissue between bone and tooth, hypotheses regarding the role of the PDL as a hydrodynamic damping mechanism during intraoral food processing have highlighted its potential importance in finite element (FE) analysis. Although experimental and constitutive models have correlated the mechanical function of the PDL tissue with its anisotropic, heterogeneous, viscoelastic and non-linear elastic nature, in many FE simulations the PDL is either present or absent, and when present is variably modelled. In addition, the small space the PDL occupies and the inability to visualize the PDL tissue using μCT scans poses issues during FE model construction and so protocols for the PDL thickness also vary. In this paper we initially test and validate the sensitivity of an FE model of a macaque mandible to variations in the Young's modulus and the thickness of the PDL tissue. We then tested the validity of the FE models by carrying out experimental strain measurements on the same mandible in the laboratory using laser speckle interferometry. These strain measurements matched the FE predictions very closely, providing confidence that material properties and PDL thickness were suitably defined. The FE strain results across the mandible are generally insensitive to the absence and variably modelled PDL tissue. Differences are only found in the alveolar region adjacent to the socket of the loaded tooth. The results indicate that the effect of the PDL on strain distribution and/or absorption is restricted locally to the alveolar bone surrounding the teeth and does not affect other regions of the mandible.
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Affiliation(s)
- Olga Panagiotopoulou
- Functional Morphology and Evolution Unit, Hull York Medical School, University of York, UK.
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Modulation of spindle discharge from jaw-closing muscles during chewing foods of different hardness in awake rabbits. Brain Res Bull 2010; 83:380-6. [DOI: 10.1016/j.brainresbull.2010.09.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2010] [Revised: 09/10/2010] [Accepted: 09/27/2010] [Indexed: 11/22/2022]
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Ross CF, Baden AL, Georgi J, Herrel A, Metzger KA, Reed DA, Schaerlaeken V, Wolff MS. Chewing variation in lepidosaurs and primates. J Exp Biol 2010; 213:572-84. [DOI: 10.1242/jeb.036822] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
Mammals chew more rhythmically than lepidosaurs. The research presented here evaluated possible reasons for this difference in relation to differences between lepidosaurs and mammals in sensorimotor systems. Variance in the absolute and relative durations of the phases of the gape cycle was calculated from kinematic data from four species of primates and eight species of lepidosaurs. The primates exhibit less variance in the duration of the gape cycle than in the durations of the four phases making up the gape cycle. This suggests that increases in the durations of some gape cycle phases are accompanied by decreases in others. Similar effects are much less pronounced in the lepidosaurs. In addition, the primates show isometric changes in gape cycle phase durations, i.e. the relative durations of the phases of the gape cycle change little with increasing cycle time. In contrast, in the lepidosaurs variance in total gape cycle duration is associated with increases in the proportion of the cycle made up by the slow open phase. We hypothesize that in mammals the central nervous system includes a representation of the optimal chew cycle duration maintained using afferent feedback about the ongoing state of the chew cycle. The differences between lepidosaurs and primates do not lie in the nature of the sensory information collected and its feedback to the feeding system, but rather the processing of that information by the CNS and its use feed-forward for modulating jaw movements and gape cycle phase durations during chewing.
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Affiliation(s)
- C. F. Ross
- Organismal Biology and Anatomy, University of Chicago, 1027 E. 57th Street, Chicago, IL 60637, USA
| | - A. L. Baden
- Interdepartmental Doctoral Program in Anthropological Sciences, Stony Brook University, Stony Brook, NY 11794, USA
| | - J. Georgi
- Department of Anatomy, Arizona College of Osteopathic Medicine, Midwestern University, 19555 North 59th Avenue, Glendale, AZ 85308, USA
| | - A. Herrel
- Département d'Ecologie et de Gestion de la Biodiversité, Muséum National d'Histoire Naturelle, 57 rue Cuvier, Case postale 55, 75231, Paris, France
| | - K. A. Metzger
- Hofstra University School of Medicine in Partnership with North Shore-LIJ, 145 Hofstra University, East Library Wing, Hempstead, NY 11549-1010, USA
| | - D. A. Reed
- Organismal Biology and Anatomy, University of Chicago, 1027 E. 57th Street, Chicago, IL 60637, USA
| | - V. Schaerlaeken
- Department of Biology, University of Antwerp, Universiteitsplein 1, B-2610 Antwerpen, Belgium
| | - M. S. Wolff
- Cariology and Comprehensive Care, College of Dentistry, New York University, 345 E 24th Street, New York, NY 10010, USA
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Kanayama H, Masuda Y, Adachi T, Arai Y, Kato T, Morimoto T. Temporal alteration of chewing jaw movements after a reversible bite-raising in guinea pigs. Arch Oral Biol 2010; 55:89-94. [DOI: 10.1016/j.archoralbio.2009.11.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2009] [Revised: 11/04/2009] [Accepted: 11/07/2009] [Indexed: 10/20/2022]
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Pröschel PA, Morneburg TR. Indications for jaw gape-related control of relative muscle activation in sequent chewing strokes. J Oral Rehabil 2009; 37:178-84. [PMID: 19968765 DOI: 10.1111/j.1365-2842.2009.02036.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Jaw muscle activity ratios in unilateral isometric biting differ from ratios of unilateral chewing but approach the latter if the jaw gape in biting is made as small as the minimum interocclusal distance (MID) of chewing. Especially, the masseter working/balancing side ratio (W/B-ratio) becomes as asymmetric as in chewing, because of reduction in balancing side (BS) masseter activity. This behaviour of ratios might reflect a 'chewing-specific' motor strategy induced when isometric biting is performed with a 'chewing-like' gape. If this hypothesis applies, activity ratios should be associated with MIDs of sequent chewing strokes in a similar manner as with incremented jaw gapes in isometric biting. To test this prediction, bilateral surface electromyograms of masseter and anterior temporalis muscles and incisor movements were recorded during unilateral chewing in 52 subjects. W/B-ratios of masseter and temporalis activities and temporalis/masseter-ratios on both sides were calculated. The ratios were related to MIDs of consecutive chewing cycles. Three of the four ratios were associated with masticatory MID in the same manner as with jaw gape in isometric biting. In particular with decreasing MID, the masseter W/B-ratio increased from 1.5 to 2.2 (P < 0.01). This increase in asymmetry was attributed to a stronger decrease in masseter activity on the BS than on the working side. We conclude that relative jaw muscle activation is associated with interocclusal distance in a similar way in isometric biting and in chewing. This analogy supports the idea of a common jaw gape-related neuromuscular strategy facilitated by afferent signalling of interocclusal distance.
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Affiliation(s)
- P A Pröschel
- Dental Clinic 2, Department of Prosthodontics, University of Erlangen-Nürnberg, Erlangen, Germany.
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Hsiao CF, Kaur G, Vong A, Bawa H, Chandler SH. Participation of Kv1 channels in control of membrane excitability and burst generation in mesencephalic V neurons. J Neurophysiol 2009; 101:1407-18. [PMID: 19144742 DOI: 10.1152/jn.91053.2008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The function and biophysical properties of low threshold Kv1 current in control of membrane resonance, subthreshold oscillations, and bursting in mesencephalic V neurons (Mes V) were examined in rat brain stem slices (P8-P12) using whole cell current and voltage patch-clamp methods. alpha-dendrotoxin application, a toxin with high specificity for Kv1.1, 1.2, and 1.6 channels, showed the presence of a low-threshold K(+) current that activated rapidly around -50 mV and was relatively noninactivating over a 1-s period and had a V(1/2)max of -36.2 mV. Other toxins, specific for individual channels containing either Kv 1.1, 1.2, or 1.3 alpha-subunits, were applied individually, or in combination, and showed that Kv1 channels are heteromeric, composed of combinations of subunits. In current-clamp mode, toxin application transformed the high-frequency resonant properties of the membrane into a low-pass filter and concomitantly reduced the frequency of the subthreshold membrane oscillations. During this period, rhythmical bursting was transformed into low-frequency tonic discharge. Interestingly, in a subset of neurons that did not show bursting, low doses of alpha-dendrotoxin (alpha-DTX) sufficient to block 50% of the low threshold Kv1 channels induced bursting and increased the resonant peak impedance and subthreshold oscillations, which was replicated with computer simulation. This suggests that a critical balance between inward and outward currents is necessary for bursting. This was replicated with computer simulation. Single cell RT-PCR and immunohistochemical methods confirmed the presence of Kv1.1, 1.2, and 1.6 alpha-subunits in Mes V neurons. These data indicate that low threshold Kv1 channels are responsible for membrane resonance, contribute to subthreshold oscillations, and are critical for burst generation.
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Affiliation(s)
- Chie-Fang Hsiao
- Department of Physiological Science, University of California at Los Angeles, Los Angeles, California, USA
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Scaling of chew cycle duration in primates. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2009; 138:30-44. [DOI: 10.1002/ajpa.20895] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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PRÖSCHEL PA, JAMAL T, MORNEBURG TR. Motor control of jaw muscles in chewing and in isometric biting with graded narrowing of jaw gape. J Oral Rehabil 2008; 35:722-8. [DOI: 10.1111/j.1365-2842.2008.01871.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Herrel A, Schaerlaeken V, Ross C, Meyers J, Nishikawa K, Abdala V, Manzano A, Aerts P. Electromyography and the evolution of motor control: limitations and insights. Integr Comp Biol 2008; 48:261-71. [PMID: 21669789 DOI: 10.1093/icb/icn025] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Electromyography (EMG), or the study of muscle activation patterns, has long been used to infer central nervous system (CNS) control of the musculoskeletal system and the evolution of that control. As the activation of the muscles at the level of the periphery is a reflection of the interaction of descending influences and local reflex control, EMG is an important tool in integrated investigations of the evolution of coordination in complex, musculoskeletal systems. Yet, the use of EMG as a tool to understand the evolution of motor control has its limitations. We here review the potential limitations and opportunities of the use of EMG in studying the evolution of motor control in vertebrates and provide original previously unpublished data to illustrate this. The relative timing of activation of a set of muscles can be used to evaluate CNS coordination of the components in a musculoskeletal system. Studies of relative timing reveal task-dependent variability in the recruitment of different populations of muscle fibers (i.e., different fiber types) within a single muscle, and left-right asymmetries in activation that need to be taken into account in comparative studies. The magnitude of muscle recruitment is strongly influenced by the instantaneous demands imposed on the system, and is likely determined by local reflex-control systems. Consequently, using EMG to make meaningful inferences about evolutionary changes in musculoskeletal control requires comparisons across similar functional tasks. Moreover, our data show that inferences about the evolution of motor control are limited in their explanatory power without proper insights into the kinematics and dynamics of a system.
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Affiliation(s)
- Anthony Herrel
- *Department of Organismic & Evolutionary Biology, Harvard University, 26 Oxford St, Cambridge, MA 02138, USA; Department of Biology, University of Antwerp, Universiteitsplein 1, B-2610 Antwerpen, Belgium; Organismal Biology and Anatomy, University of Chicago, 1027 E. 57th Street, Chicago, IL 60637, USA; Department of Biology, 221 Morrill Science Center, University of Massachusetts at Amherst, Amherst, MA 01003, USA; Department of Biological Sciences, Northern Arizona University, Flagstaff AZ 86011-5640, USA; Instituto de Herpetología, Fundación Miguel Lillo-CONICET, Fac. de Cs. Naturales (UNT) Miguel Lillo 251 4000 Tucumán, Argentina; CICyTTP-CONICET, Matteri y España (3105), Diamante, Entre Ríos, Argentina
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SHIMADA A, TANAKA M, YAMASHITA R, NOGUCHI K, TORISU T, YAMABE Y, FUJII H, MURATA H. Automatic regulation of occlusal force because of hardness-change of the bite object. J Oral Rehabil 2007; 35:12-9. [DOI: 10.1111/j.1365-2842.2007.01746.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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ASHIDA ICHIRO, IWAMORI HAJIME, KAWAKAMI SHINYA, MIYAOKA YOZO, MURAYAMA ATSUKO. ANALYSIS OF PHYSIOLOGICAL PARAMETERS OF MASSETER MUSCLE ACTIVITY DURING CHEWING OF AGARS IN HEALTHY YOUNG MALES. J Texture Stud 2007. [DOI: 10.1111/j.1745-4603.2007.00087.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Capra NF, Hisley CK, Masri RM. The influence of pain on masseter spindle afferent discharge. Arch Oral Biol 2006; 52:387-90. [PMID: 17126284 PMCID: PMC1868482 DOI: 10.1016/j.archoralbio.2006.10.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2006] [Revised: 10/04/2006] [Accepted: 10/10/2006] [Indexed: 12/26/2022]
Abstract
Muscle spindles provide proprioceptive feedback supporting normal patterns of motor activity and kinesthetic sensibility. During mastication, jaw muscle spindles play an important role in monitoring and regulating the chewing cycle and the bite forces generated during mastication. Both acute and chronic orofacial pain disorders are associated with changes in proprioceptive feedback and motor function. Experimental jaw muscle pain also alters the normal response of masseter spindle afferents to ramp and hold jaw movements. It has been proposed that altered motor function and proprioceptive input results from group III muscle afferent modulation of the fusimotor system which alters spindle afferent sensitivity in limb muscles. The response to nociceptive stimuli may enhance or reduce the response of spindle afferents to proprioceptive stimuli. Several experimental observations suggesting the possibility that a similar mechanism also functions in jaw muscles are presented in this report. First, evidence is provided to show that nociceptive stimulation of the masseter muscle primarily influences the amplitude sensitivity of spindle afferents with relatively little effect on the dynamic sensitivity. Second, reversible inactivation of the caudal trigeminal nuclei attenuates the nociceptive modulation of spindle afferents. Finally, functionally identified gamma-motoneurons in the trigeminal motor nucleus are modulated by intramuscular injection with algesic substances. Taken together, these results suggest that pain-induced modulation of spindle afferent responses are mediated by small diameter muscle afferents and that this modulation is dependent, in part, on the relay of muscle nociceptive information from trigeminal subnucleus caudalis onto trigeminal gamma-motoneurons. The implication of these results will be considered in light of current theories on the relationship between jaw muscle pain and oral motor function.
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Affiliation(s)
- Norman F Capra
- Department of Biomedical Sciences, Baltimore College of Dental Surgery, University of Maryland Baltimore, 666 W. Baltimore Street, Baltimore, MD 21201, USA.
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31
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Lund JP, Kolta A. Generation of the Central Masticatory Pattern and Its Modification by Sensory Feedback. Dysphagia 2006; 21:167-74. [PMID: 16897322 DOI: 10.1007/s00455-006-9027-6] [Citation(s) in RCA: 175] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mammalian mastication results from the interaction of an intrinsic rhythmical neural pattern and sensory feedback generated by the interaction of the effecter system (muscles, bones, joints, teeth, soft tissues) with food. The main variables that explain variation in the pattern of human mastication are the subjects themselves, their age, the type of food being eaten, and time during a sequence of movements. The intrinsic pattern of mastication is generated by a central pattern generator (CPG) located in the pons and medulla. The output of the CPG is modified by inputs that descend from higher centers of the brain and by feedback from sensory receptors. Intraoral touch receptors, muscle spindles in the jaw-closing muscles, and specialized mechanoreceptors in the periodontal ligament have especially powerful effects on movement parameters.
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Affiliation(s)
- James P Lund
- Faculty of Dentistry, McGill University, Montreal, Quebec, H3A 2B2, Canada.
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Adaption of the central masticatory pattern to the biomechanical properties of food. ACTA ACUST UNITED AC 2005. [DOI: 10.1016/j.ics.2005.07.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Roatta S, Windhorst U, Djupsjöbacka M, Lytvynenko S, Passatore M. Effects of sympathetic stimulation on the rhythmical jaw movements produced by electrical stimulation of the cortical masticatory areas of rabbits. Exp Brain Res 2004; 162:14-22. [PMID: 15551082 DOI: 10.1007/s00221-004-2102-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2004] [Accepted: 08/18/2004] [Indexed: 10/26/2022]
Abstract
The somatomotor and sympathetic nervous systems are intimately linked. One example is the influence of peripheral sympathetic fibers on the discharge characteristics of muscle spindles. Since muscle spindles play important roles in various motor behaviors, including rhythmic movements, the working hypothesis of this research was that changes in sympathetic outflow to muscle spindles can change rhythmic movement patterns. We tested this hypothesis in the masticatory system of rabbits. Rhythmic jaw movements and EMG activity induced by long-lasting electrical cortical stimulation were powerfully modulated by electrical stimulation of the peripheral stump of the cervical sympathetic nerve (CSN). This modulation manifested itself as a consistent and marked reduction in the excursion of the mandibular movements (often preceded by a transient modest enhancement), which could be attributed mainly to corresponding changes in masseter muscle activity. These changes outlasted the duration of CSN stimulation. In some of the cortically evoked rhythmic jaw movements (CRJMs) changes in masticatory frequency were also observed. When the jaw-closing muscles were subjected to repetitive ramp-and-hold force pulses, the CRMJs changed characteristics. Masseter EMG activity was strongly enhanced and digastric EMG slightly decreased. This change was considerably depressed during CSN stimulation. These effects of CSN stimulation are similar in sign and time course to the depression exerted by sympathetic activity on the jaw-closing muscle spindle discharge. It is suggested that the change in proprioceptive information induced by an increase in sympathetic outflow (a) has important implications even under normal conditions for the control of motor function in states of high sympathetic activity, and (b) is one of the mechanisms responsible for motor impairment under certain pathological conditions such as chronic musculoskeletal head-neck disorders, associated with stress conditions.
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Affiliation(s)
- S Roatta
- Physiology Division, Department of Neuroscience, Medical School, University of Turin, c.so Raffaello 30, 10125 Turin, Italy.
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Masuda Y, Kim SK, Kato T, Iida S, Yoshida A, Tachibana Y, Morimoto T. Different corticostriatal projections from two parts of the cortical masticatory area in the rabbit. Exp Brain Res 2004; 161:397-404. [PMID: 15502983 DOI: 10.1007/s00221-004-2073-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2004] [Accepted: 07/16/2004] [Indexed: 11/26/2022]
Abstract
The cortical masticatory area (CMA) elicits rhythmic jaw movements in response to repetitive stimulation and is involved in the control of mastication. Based on jaw movement patterns, the CMA is divided into two parts. One is the part of the CMA in which a T-pattern similar to jaw movements during food transport in natural mastication is evoked by electrical stimulation. The other is more dorsomedially located, and during chewing a C-pattern similar to jaw movements can be induced. However, it is still not known which region of the putamen receives projections from the CMA and whether projections originate from both parts of the CMA. In this study, electrophysiological and histological experiments were undertaken in rabbits to investigate projections from the CMA to the putamen. Both experiments showed that the ventral region of the putamen received projections from the CMA. The density of the projections from the CMA area inducing the T-pattern seemed to be higher than that from the area inducing the C-pattern. Furthermore, the peak latency of the evoked potentials from stimulation of the CMA area inducing the T-pattern was shorter than that from stimulation of the area inducing the C-pattern. The data obtained from the present study indicate the functional role of the ventral region of the putamen in the regulation of mastication, and further suggest that the corticostriatal pathway is involved in the transition between behavioral jaw movement patterns.
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Affiliation(s)
- Yuji Masuda
- Department of Oral Physiology, Graduate School of Dentistry, Osaka University, Osaka, Japan.
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Abstract
Mental stress may cause a dissociation of sympathetic outflow to different regions. However, it remains unclear how the sympathetic outflow to jaw muscles is related to other sympathetic outflow under mental stress. The objective of this study was to clarify the temporal relationship between the finger sweat expulsion elicited by mental stress and the hemodynamic and electromyographic changes in the masseter muscle. Healthy adult female volunteers participated in this study. Masseteric hemodynamic changes were closely time-related to mental stress, showing a decrease in oxygen saturation of muscle blood around the onset of mental stress. In contrast, EMG activity of jaw-closing muscles was not time-related to mental stress. These results suggest that mental stress induces hemodynamic changes that are not associated with EMG activity in the masseter muscle of healthy adult females.
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Affiliation(s)
- O Hidaka
- Department of Orthodontics and Dentofacial Orthopedics, Graduate School of Dentistry, Osaka University, 1-8 Yamadaoka, Suita, Osaka 565-0871, Japan.
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BOSMAN FREDERIK, BILT ANDRIES, ABBINK JANH, GLAS HILBERTW. NEUROMUSCULAR CONTROL MECHANISMS IN HUMAN MASTICATION. J Texture Stud 2004. [DOI: 10.1111/j.1745-4603.2004.tb00833.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Zhang W, Kobayashi M, Moritani M, Masuda Y, Dong J, Yagi T, Maeda T, Morimoto T. An involvement of trigeminal mesencephalic neurons in regulation of occlusal vertical dimension in the guinea pig. J Dent Res 2003; 82:565-9. [PMID: 12821720 DOI: 10.1177/154405910308200715] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Although the occlusal vertical dimension (OVD) is strictly controlled, the neuronal mechanism of its regulation is still unclear. We hypothesize that neurons in the trigeminal mesencephalic nucleus (MesV) play an important role in the regulation of the OVD, because the MesV receives the projection from jaw-closing muscle spindles and periodontal mechanoreceptors. We measured the temporal OVD change in the guinea pig to study the effects of MesV lesions on the OVD. OVD-raised animals without MesV lesions showed a rapid OVD decrease to the same level as that in naïve controls, followed by an OVD increase after the OVD-raising appliance was removed. In contrast, OVD-raised animals with MesV lesions showed only a slight decrease in the OVD for 15 days after removal of the appliance, and then the OVD increased. The time-course of OVD development in normal-bite animals with MesV lesions was similar to that of naïve controls. These results suggest that MesV neurons are involved in OVD regulation.
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Affiliation(s)
- W Zhang
- Department of Oral Physiology, Osaka University Graduate School of Dentistry, Suita, Japan
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Tanaka S, Wu N, Hsaio CF, Turman J, Chandler SH. Development of inward rectification and control of membrane excitability in mesencephalic v neurons. J Neurophysiol 2003; 89:1288-98. [PMID: 12612052 DOI: 10.1152/jn.00850.2002] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The present study was performed to assess the postnatal development and functional roles of inward rectifying currents in rat mesencephalic trigeminal (Mes V) neurons, which are involved in the genesis and control of oral-motor activities. Whole cell voltage-clamp recordings obtained from Mes V neurons in brain stem slices identified fast (I(KIR)) and slow (I(h)) inward rectifying currents, which were specifically blocked by BaCl(2) (300-500 microM) or 4-(N-ethyl-N-phenylamino)-1,2-dimethyl-6-(methylamino) pyrimidinium chloride (ZD 7288, 10 microM), respectively. The whole cell current density for these channels increased between postnatal days 2 to 12 (P2-P12), and the time courses for I(h) activation and deactivation were each well described by two time constants. Application of ZD 7288 produced membrane hyperpolarization in the majority of cells and prolonged afterhyperpolarization repolarization. Additionally, in the presence of ZD 7288, spike frequency was decreased and adaptation was more pronounced. Interestingly, these neurons exhibited a voltage-dependent membrane resonance (<10 Hz) that was prominent around resting potential and more negative to rest and was blocked by ZD 7288. These results suggest that I(h) contributes to stabilizing resting membrane potential and controlling cell excitability. The presence of I(h) imparts the neuron with the unique property of low-frequency membrane resonance; the ability to discriminate between synaptic inputs based on frequency content.
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Affiliation(s)
- Susumu Tanaka
- Department of Physiological Science and the Brain Research Institute, Los Angeles, California 90095, USA
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Komuro A, Morimoto T, Iwata K, Inoue T, Masuda Y, Kato T, Hidaka O. Putative feed-forward control of jaw-closing muscle activity during rhythmic jaw movements in the anesthetized rabbit. J Neurophysiol 2001; 86:2834-44. [PMID: 11731540 DOI: 10.1152/jn.2001.86.6.2834] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
When a thin plastic test strip of various hardness is placed between the upper and lower teeth during rhythmical jaw movements induced by electrical stimulation of the cortical masticatory area (CMA) in anesthetized rabbits, electromyographic (EMG) activity of the masseter muscle is facilitated in a hardness-dependent manner. This facilitatory masseteric response (FMR) often occurred prior to contact of the teeth to the strip, and thus preceded the onset of the masticatory force. Since this finding suggests involvement of a feed-forward mechanism in the induction of the FMR, the temporal relationship between the onset of the FMR and that of the masticatory force was analyzed in five sequential masticatory cycles after application of the strip. The FMR was found to precede the onset of masticatory force from the second masticatory cycle after application of the strip, but never did in the first cycle. This finding supports the concept of a feed-forward control mechanism that modulates FMR timing. Furthermore, the FMR preceding the force onset disappeared after making a lesion of the mesencephalic trigeminal nucleus (MesV) where the ganglion cells of the muscle spindle afferents from the jaw-closing muscles are located. In contrast, no such change occurred after blocking periodontal afferents by transection of both the maxillary and the inferior alveolar nerves. The putative feed-forward control of the FMR is therefore dependent mainly on sensory inputs from the muscle spindles, but little on those from the periodontal receptors, if any. We further examined the involvement of the CMA with the putative feed-forward control of the FMR via the transcortical loop. For this purpose, rhythmical jaw movements were induced by stimulation of the pyramidal tract. No significant change in the timing of the FMR occurred after the CMA ablation, which strongly suggests that the CMA is not involved in the putative feed-forward control of the FMR. The FMR was also noted to increase significantly in a hardness-dependent manner even after the MesV lesion, although the rate of increment decreased significantly. Contribution of muscle spindles and periodontal receptors to the hardness-dependent change of the FMR is discussed.
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Affiliation(s)
- A Komuro
- Department of Oral Physiology, Graduate School of Dentistry, Osaka University, Osaka 565-0871, Japan
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Yashiro K, Fujii M, Hidaka O, Takada K. Kinematic modeling of jaw-closing movement during food breakage. J Dent Res 2001; 80:2030-4. [PMID: 11759016 DOI: 10.1177/00220345010800111601] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
It has been demonstrated that the vertical jaw movement trajectories during gum-chewing can be explained by jerk-cost minimization. However, it is uncertain whether the masticatory jaw movement in space can be predicted by the minimum-jerk model. The aims of the present study were to develop minimum-jerk models that would explain 3D masticatory jaw movements with different hardnesses of foods, and to evaluate if the models can predict the movements accurately. The 3D masticatory jaw movement during food breakage was formulated for two types of test foods. The coefficients of determination (R2) between the measured and model-based values ranged from 0.846 to 0.882. Differences were found in the kinematic parameters between the test foods. The results suggest that the models predict the 3D jaw movements during food breakage and are effective in differentiating among the kinematic features of masticatory jaw movements that are peculiar to the mechanical properties of foodstuffs.
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Affiliation(s)
- K Yashiro
- Department of Orthodontics and Dentofacial Orthopedics, Graduate School of Dentistry, Osaka University, Suita, Japan
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Membrane resonance and subthreshold membrane oscillations in mesencephalic V neurons: participants in burst generation. J Neurosci 2001. [PMID: 11356860 DOI: 10.1523/jneurosci.21-11-03729.2001] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Trigeminal mesencephalic (Mes V) neurons are critical components of the circuits controlling oral-motor activity. The possibility that they can function as interneurons necessitates a detailed understanding of the factors controlling their soma excitability. Using whole-cell patch-clamp recording, in vitro, we investigated the development of the ionic mechanisms responsible for the previously described subthreshold membrane oscillations and rhythmical burst discharge in Mes V neurons from rats ages postnatal day (P) 2-12. We found that the oscillation amplitude and frequency increased during development, whereas bursting emerged after P6. Furthermore, when bursting was initiated, the spike frequency was largely determined by the oscillation frequency. Frequency domain analysis indicated that these oscillations emerged from the voltage-dependent resonant properties of Mes V neurons. Low doses of 4-aminopyridine (<100 microm) reduced the oscillations and abolished resonance in most neurons, suggesting that the resonant current is a steady-state K(+) current (I(4-AP)). Sodium ion replacement or TTX reduced substantially the oscillations and peak amplitude of the resonance, suggesting the presence of a persistent Na(+) current (I(NaP)) that functions to amplify the resonance and facilitate the emergence of subthreshold oscillations and bursting.
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Komuro A, Masuda Y, Iwata K, Kobayashi M, Kato T, Hidaka O, Morimoto T. Influence of food thickness and hardness on possible feed-forward control of the masseteric muscle activity in the anesthetized rabbit. Neurosci Res 2001; 39:21-9. [PMID: 11164250 DOI: 10.1016/s0168-0102(00)00192-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The facilitatory masseteric muscle response (FMR) elicited by polyurethane foam strip application between the opposing molars during cortically-induced rhythmic jaw movements (CRJMs) was induced earlier than masticatory force onset. The occurrence of this early response of the FMR (e-FMR) could not be explained by a simple reflex mechanism. One possible mechanism of the e-FMR is the involvement of a feed-forward control mechanism of the masticatory jaw movement. In the present study, experimentally designed polyurethane foam strips with various thickness and hardness were applied during CRJMs and analyzed in terms of how the e-FMR was modulated by the food hardness and thickness. The FMR onset was not related to the strip thickness or the strip hardness. However, the magnitude of the e-FMR increased in a thickness and a hardness-dependent manner. The sensory information of the food properties in the masticatory cycle may make the FMR adequate to chewing of the food in the following cycle, and such modulation may help chewing rhythms remain stable.
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Affiliation(s)
- A Komuro
- Department of Oral Physiology, Faculty of Dentistry, Osaka University, 1-8 Yamadaoka, Suita, Osaka 565-0871, Japan.
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