Research in methodologies for modelling the oral cavity.

The paper aims to explore the current state of understanding surrounding in silico oral modelling. This involves exploring methodologies, technologies and approaches pertaining to the modelling of the whole oral cavity; both internally and externally visible structures that may be relevant or appropriate to oral actions. Such a model could be referred to as a 'complete model' which includes consideration of a full set of facial features (i.e. not only mouth) as well as synergistic stimuli such as audio and facial thermal data. 3D modelling technologies capable of accurately and efficiently capturing a complete representation of the mouth for an individual have broad applications in the study of oral actions, due to their cost-effectiveness and time efficiency. This review delves into the field of clinical phonetics to classify oral actions pertaining to both speech and non-speech movements, identifying how the various vocal organs play a role in the articulatory and masticatory process. Vitaly, it provides a summation of 12 articulatory recording methods, forming a tool to be used by researchers in identifying which method of recording is appropriate for their work. After addressing the cost and resource-intensive limitations of existing methods, a new system of modelling is proposed that leverages external to internal correlation modelling techniques to create a more efficient models of the oral cavity. The vision is that the outcomes will be applicable to a broad spectrum of oral functions related to physiology, health and wellbeing, including speech, oral processing of foods as well as dental health. The applications may span from speech correction, designing foods for the aging population, whilst in the dental field we would be able to gain information about patient's oral actions that would become part of creating a personalised dental treatment plan.

Nonlinear elasticity and short-range mechanical coupling govern the rate and symmetry of mouth opening in Hydra.

Hydra has a tubular bilayered epithelial body column with a dome-shaped head on one end and a foot on the other. Hydra lacks a permanent mouth: its head epithelium is sealed. Upon neuronal activation, a mouth opens at the apex of the head which can exceed the body column diameter in seconds, allowing Hydra to ingest prey larger than itself. While the kinematics of mouth opening are well characterized, the underlying mechanism is unknown. We show that Hydra mouth opening is generated by independent local contractions that require tissue-level coordination. We model the head epithelium as an active viscoelastic nonlinear spring network. The model reproduces the size, timescale and symmetry of mouth opening. It shows that radial contractions, travelling inwards from the outer boundary of the head, pull the mouth open. Nonlinear elasticity makes mouth opening larger and faster, contrary to expectations. The model correctly predicts changes in mouth shape in response to external forces. By generating innervated : nerve-free chimera in experiments and simulations, we show that nearest-neighbour mechanical signalling suffices to coordinate mouth opening. Hydra mouth opening shows that in the absence of long-range chemical or neuronal signals, short-range mechanical coupling is sufficient to produce long-range order in tissue deformations.

The detection and modulation of piperine in the human oral cavity.

Piperine is an alkaloid that is responsible for the pungency of black pepper and long pepper. This hydrophobic compound causes a spicy sensation when it comes in contact with trigeminal neurons of the oral cavity. Piperine has low solubility in water, which presents difficulties in examining the psychophysical properties of this stimulus by standard aqueous chemosensory tests. This report describes approaches that utilize novel edible film formulations for delivering precise amounts of piperine to the human oral cavity. These films were then used to identify detection thresholds for piperine, and to identify the chemosensory properties of this compound at suprathreshold amounts. When incorporated into edible films, mean detection thresholds for piperine were approximately 35 nanomoles. For suprathreshold studies, edible films that contained 4000 nanomole amounts of piperine yielded variable intensity responses in subjects, with mean intensities in the moderate range. This amount of piperine caused significant self-desensitization, which was partially reversed after 60-90 min. In contrast, edible films that contained lower amounts of piperine yielded mean intensity ratings in the weak range and showed essentially no self-desensitization. The application of piperine to the circumvallate region of the tongue caused moderate intensity responses that were identified as primarily spicy, and rarely bitter. In addition, oral rinses with aqueous sucrose solutions decreased mean intensities for piperine by approximately twenty-five percent over sixty seconds. Blockage of nasal airflow significantly decreased piperine intensities in the oral cavity. These two findings indicate that oral sucrose or blockage of nasal airflow can modulate piperine perception in the human oral cavity. Finally, these results indicate that a variety of excipients can be included in edible film formulations for presenting piperine to the oral cavity at stimulus amounts that cause quantifiable chemosensory responses.

Visualization of the relationship between electrogustometry and whole mouth test using multidimensional scaling.

Interpreting the relationship between different taste function tests of different stimuli, such as chemical and electrical stimulation, is still poorly understood. This study aims to analyze visually as well as quantitatively how to interpret the relationship of results between taste function tests using different stimuli. Patients who underwent the whole mouth test and Electrogustometry (EGM) at a tertiary medical center between August 2018 and December 2018 were reviewed retrospectively with electronic medical records. Of the 110 patients, a total of 86 adults who self-reported that their taste function was normal through a questionnaire were enrolled. EGM measured the thresholds of the chorda tympani (CT) and glossopharyngeal nerve (GL) area of the tongue. The whole mouth test measured detection and recognition thresholds for sweet, salty, bitter, sour, and umami taste. Statistical analyses of Pearson's, Spearman's rank and polyserial correlation and multidimensional scaling (MDS) was performed. The EGM threshold for the average value of both CT regions and the recognition threshold of the whole mouth test were significantly correlated in sweet, salty, bitter, and sour taste (r = 0.244-0.398, P < 0.05), and the detection threshold was correlated only significant in sweet (r = 0.360, P = 0.007). In the MDS analysis results, the three-dimensional (D) solution was chosen over the 2-D solution because of the lower stress. Detection-, recognition threshold of whole mouth test and EGM thresholds of CT and GL area, those were standardized by Z-score, formed well-distinguished sections in the MDS analyses. The EGM threshold of the CT area was closer to the detection and recognition thresholds than the EGM threshold of the GL area. In general, the EGM threshold was closer to the recognition threshold than the detection threshold for each taste. Overall, visualization of the relationship of whole mouth test and EGM by MDS was in good agreement with quantitative analysis. EGM and whole mouth test seem to reflect different aspects of taste. However, when interpreting the EGM results, the EGM threshold of the CT area will show more similarity to the recognition threshold than the detection threshold for the whole mouth test.

A somato-cognitive action network alternates with effector regions in motor cortex.

Motor cortex (M1) has been thought to form a continuous somatotopic homunculus extending down the precentral gyrus from foot to face representations1,2, despite evidence for concentric functional zones3 and maps of complex actions4. Here, using precision functional magnetic resonance imaging (fMRI) methods, we find that the classic homunculus is interrupted by regions with distinct connectivity, structure and function, alternating with effector-specific (foot, hand and mouth) areas. These inter-effector regions exhibit decreased cortical thickness and strong functional connectivity to each other, as well as to the cingulo-opercular network (CON), critical for action5 and physiological control6, arousal7, errors8 and pain9. This interdigitation of action control-linked and motor effector regions was verified in the three largest fMRI datasets. Macaque and pediatric (newborn, infant and child) precision fMRI suggested cross-species homologues and developmental precursors of the inter-effector system. A battery of motor and action fMRI tasks documented concentric effector somatotopies, separated by the CON-linked inter-effector regions. The inter-effectors lacked movement specificity and co-activated during action planning (coordination of hands and feet) and axial body movement (such as of the abdomen or eyebrows). These results, together with previous studies demonstrating stimulation-evoked complex actions4 and connectivity to internal organs10 such as the adrenal medulla, suggest that M1 is punctuated by a system for whole-body action planning, the somato-cognitive action network (SCAN). In M1, two parallel systems intertwine, forming an integrate-isolate pattern: effector-specific regions (foot, hand and mouth) for isolating fine motor control and the SCAN for integrating goals, physiology and body movement.

Aphagy and vestigial stylets in first-instar nymphs of Aradidae (Hemiptera, Heteroptera).

Aradidae are known for their remarkably long stylets, coiled at rest in the anterior part of the head. However, previous reports indicated that at least some species lacked stylets during the first nymphal instar. A more detailed examination of Aradus betulae 1st-instar nymphs showed that their mandibular and maxillary stylets are abnormally short, not coiled, improperly interlocked, and clearly non-functional. The anteclypeus is relatively small and its internal diverticulum, which accommodates the stylet coil in the older stages, is vestigial. In contrast, the labium, labrum, food canal, and associated structures and muscles, including protractors and retractors of the stylets, are all normally developed. First-instar nymphs of Aradidae are the first known Heteroptera with non-functional mouthparts. To explain this phenomenon, a hypothesis is proposed which links previously unexplained records of non-feeding (but endowed with regular, functional mouthparts) 1st-instar nymphs of various pentatomomorphan families with the special role of that stage in acquiring microbial gut symbionts. A presumed loss of symbionts in the ancestors of Aradidae may have led to reduction of the now useless stylets in the first instar, which retained aphagy, despite a spectacular elongation of stylets in the older, feeding instars.

In situ quantitative assessment of food oral processing parameters: A review of feasible techniques and devices.

Oral processing is a combination of various actions, the detailed description of which has always been the subject of relevant research. By means of imaging technology and sensory evaluation, more knowledge of oral processing have been accumulated. Presently, the advances in sensory technology have added quantitative parameters to the qualitative description of oral processing, which also enriched the specifics of each action. Previous studies have shown that oral processing includes lip closure, dental occlusion, masticatory muscles activity, tongue movement, and swallowing, whose processing contains rich information such as the movement of organ and the intensity of organ contacts. "Quantification" was taken in this review as the basic feature of in situ detection information, the relevant parameters and feasible methods for the quantitative description of each activity was recorded in detail. In addition, basic problems and feasible optimization schemes of the existing in situ detection device are also proposed in the hope of promoting the development of in situ detection device thus providing available information for the description of oral processing.

Mouthpart adaptations of antlion larvae facilitate prey handling and fluid feeding in sandy habitats.

Antlion larvae are fluid-feeding ambush predators that feed on arthropods trapped in their funnel-shaped pits built in sandy habitats; however, details are lacking about their feeding mechanism. Here, we tested the hypothesis that the antlion, Myrmeleon crudelis, has adaptations that facilitate fluid feeding in sandy habitats. We measured contact angles of water droplets and used the capillary-rise technique to assess mouthpart wettability. A structural organization was discovered that provides a hydrophobic-hydrophilic wetting dichotomy that simultaneously supports self-cleaning and fluid uptake and is enabled by antiparallel movements of the maxillae. The mouthparts also are augmented by their mechanical properties, including maxillae and mandible tips that might be heavily sclerotized, as determined by confocal microscopy, which likely facilitates piercing prey. Our findings provide insight into how antlion larvae have overcome the challenges of fluid feeding in sandy habitats, which probably contributed to their success and widespread distribution.

Comparison of international and Japanese predictive equations for maximal respiratory mouth pressures.

Respiratory muscle weakness has attracted attention because sarcopenia and respiratory muscle dysfunction may play a key role in the development of respiratory failure. To evaluate respiratory muscle strength appropriately, individual factors such as sex, age, body size, and ethnicity should be considered. This study aimed to compare equations available in Japan and other countries for predicting respiratory muscle strength. We tested 21 equations for maximal inspiratory pressure (MIP) and 17 for maximal expiratory pressure (MEP) for each sex (76 equations in total) in 159 normal, healthy subjects. We observed wide variations in the overall agreement among the MIP and MEP equations. Some equations showed a proper normal distribution, with median values of almost 100%, and the Japanese equations released in 1997 generally showed the best distributions of both %MIP and %MEP. We can conclude that it is better to use Japanese equations when evaluating respiratory muscle strength in Japanese subjects.

Bioadhesion on Textured Interfaces in the Human Oral Cavity-An In Situ Study.

Extensive biofilm formation on materials used in restorative dentistry is a common reason for their failure and the development of oral diseases like peri-implantitis or secondary caries. Therefore, novel materials and strategies that result in reduced biofouling capacities are urgently sought. Previous research suggests that surface structures in the range of bacterial cell sizes seem to be a promising approach to modulate bacterial adhesion and biofilm formation. Here we investigated bioadhesion within the oral cavity on a low surface energy material (perfluorpolyether) with different texture types (line-, hole-, pillar-like), feature sizes in a range from 0.7-4.5 µm and graded distances (0.7-130.5 µm). As a model system, the materials were fixed on splints and exposed to the oral cavity. We analyzed the enzymatic activity of amylase and lysozyme, pellicle formation, and bacterial colonization after 8 h intraoral exposure. In opposite to in vitro experiments, these in situ experiments revealed no clear signs of altered bacterial surface colonization regarding structure dimensions and texture types compared to unstructured substrates or natural enamel. In part, there seemed to be a decreasing trend of adherent cells with increasing periodicities and structure sizes, but this pattern was weak and irregular. Pellicle formation took place on all substrates in an unaltered manner. However, pellicle formation was most pronounced within recessed areas thereby partially masking the three-dimensional character of the surfaces. As the natural pellicle layer is obviously the most dominant prerequisite for bacterial adhesion, colonization in the oral environment cannot be easily controlled by structural means.

Suction feeding biomechanics of Polypterus bichir: investigating linkage mechanisms and the contributions of cranial kinesis to oral cavity volume change.

Many fishes use substantial cranial kinesis to rapidly increase buccal cavity volume, pulling prey into the mouth via suction feeding. Living polypterids are a key lineage for understanding the evolution and biomechanics of suction feeding because of their phylogenetic position and unique morphology. Polypterus bichir have fewer mobile cranial elements compared with teleosts [e.g. immobile (pre)maxillae] but successfully generate suction through dorsal, ventral and lateral oral cavity expansion. However, the relative contributions of these motions to suction feeding success have not been quantified. Additionally, extensive body musculature and lack of opercular jaw opening linkages make P. bichir of interest for examining the role of cranial versus axial muscles in driving mandibular depression. Here, we analyzed the kinematics of buccal expansion during suction feeding in P. bichir using X-ray Reconstruction of Moving Morphology (XROMM) and quantified the contributions of skeletal elements to oral cavity volume expansion and prey capture. Mouth gape peaks early in the strike, followed by maximum cleithral and ceratohyal rotations, and finally by opercular and suspensorial abductions, maintaining the anterior-to-posterior movement of water. Using a new method of quantifying bones' relative contributions to volume change (RCVC), we demonstrate that ceratohyal kinematics are the most significant drivers of oral cavity volume change. All measured cranial bone motions, except abduction of the suspensorium, are correlated with prey motion. Lastly, cleithral retraction is largely concurrent with ceratohyal retraction and jaw depression, while the sternohyoideus maintains constant length, suggesting a central role of the axial muscles, cleithrum and ceratohyal in ventral expansion.

Experience-dependent learning of behavioral laterality in the scale-eating cichlid Perissodus microlepis occurs during the early developmental stage.

Behavioral laterality-typically represented by human handedness-is widely observed among animals. However, how laterality is acquired during development remains largely unknown. Here, we examined the effect of behavioral experience on the acquisition of lateralized predation at different developmental stages of the scale-eating cichlid fish Perissodus microlepis. Naïve juvenile fish without previous scale-eating experience showed motivated attacks on prey goldfish and an innate attack side preference. Following short-term predation experience, naïve juveniles learned a pronounced lateralized attack using their slightly skewed mouth morphology, and improved the velocity and amplitude of body flexion to succeed in foraging scales during dominant-side attack. Naïve young fish, however, did not improve the dynamics of flexion movement, but progressively developed attack side preference and speed to approach the prey through predation experience. Thus, the cichlid learns different aspects of predation behavior at different developmental stages. In contrast, naïve adults lost the inherent laterality, and they neither developed the lateralized motions nor increased their success rate of predation, indicating that they missed appropriate learning opportunities for scale-eating skills. Therefore, we conclude that behavioral laterality of the cichlid fish requires the integration of genetic basis and behavioral experiences during early developmental stages, immediately after they start scale-eating.

Effect of suprahyoid muscles on mouth opening with and without lateral pterygoid muscle: 3D inverse dynamic model analysis.

Objective: To evaluate the contribution of suprahyoid muscles to mouth opening in different hyoid bone positions.Methods: The jaw-opening and closing movements were imposed on the 3D inverse dynamic jaw model with and without the lateral pterygoid muscle (LPM). The activation of the muscles was evaluated for eight different positions of the hyoid bone.Results: The muscles with 100% activation provided maximum mouth opening (MMO). When the hyoid bone was replaced, the muscles could achieve MMO at the 135º, 180º, and 225º points with the LPM. Mouth opening was estimated to be 36.8 mm in the absence of the LPM. A jaw opening greater than 36.8 mm was seen when the hyoid bone was repositioned at the 90º, 180º, and 135º points.Discussion: The contribution of suprahyoid muscles to mouth opening varies in different hyoid bone positions, with the inferior and anterior positions having a positive impact.

Ejercicios motores orofaciales no verbales: uso y conocimiento de los fonoaudiólogos que trabajan con personas con trastornos de los sonidos del habla / Nonspeech oral motor exercises: use and knowledge of speech-language pathologists working with people with speech sound disorders

Estudios realizados en diferentes países (por ejemplo, Australia, Canadá, India, República de Irlanda, EE.UU., Reino Unido) han demostrado que los fonoaudiólogos utilizan ejercicios motores orofaciales no verbales (EMONV) para tratar los trastornos de los sonidos del habla (TSH), atrayendo atención hacia el sustancial debate que existe respecto a la eficacia clínica de estos ejercicios. En este contexto, el presente estudio tuvo como objetivo investigar y caracterizar el uso de los EMONV por parte de fonoaudiólogos portugueses que realizan intervenciones en TSH y evaluar el conocimiento que lo respalda. Para ello, se invitó a profesionales de la fonoaudiología que trabajan con niños con TSH a completar un cuestionario basado en Thomas y Kaipa (2015). Un total de 184 participantes respondió a la encuesta; 93,5% informó contar con conocimientos sobre los EMONV, 78.5% utiliza EMONV para el tratamiento de TSH y 80,2% los considera efectivos en el tratamiento del TSH (89% indicó que adquirió su conocimiento sobre EMONV a través de cursos de pregrado y posgrado; 98,5% informó que utiliza los EMONV para mejorar las funciones motoras de los órganos fonoarticulatorios). Este estudio ofrece una descripción general del uso de los EMONV por parte de fonoaudiólogos portugueses en la intervención en niños con TSH. Muchos de los participantes en este estudio informaron que utilizan EMONV en el tratamiento de TSH, independientemente de la falta de evidencia para respaldar su uso en este contexto. Estos hallazgos demuestran que el porcentaje de fonoaudiólogos en Portugal que utilizan EMONV es similar al encontrado en los EE.UU., Reino Unido, Canadá e India, pero diferente del porcentaje en Australia e Irlanda.

Previous studies, conducted in different countries (e.g. Australia, Canada, India, Republic of Ireland, USA, UK), have shown that speech-language pathologists (SLPs) use nonspeech oral motor exercises (NSOMEs) to treat speech sound disorders (SSDs), bringing attention to the substantial debate regarding the clinical effectiveness of NSOMEs. The aim of the present study was to investigate and characterize the use of NSOMEs by Portuguese SLPs in the intervention of SSDs, and to analyze the evidence that supports it. To do so, SLPs who provide therapy to children with SSDs were invited to complete an online questionnaire, based on a previous survey conducted in India by Thomas and Kaipa (2015). A total of 184 participants responded to the survey; 93.5% reported knowing about NSOMEs, 78.5% used NSOMEs in their intervention for SSDs, and 80.2% considered them effective in treating SSDs (89% indicated that their knowledge about NSOMEs was acquired through graduate and post-graduate courses; 98.5% reported that theyused NSOMEs to improve the motor function of the articulators). This study offers an overview of Portuguese speech-language pathologists' reported use of NSOMEs as part of the intervention of speech sound disorders in children. Many of the participants in this study reported that they did use NSOMEs in SSD treatments, regardless of the lack of evidence to support their use in this context. Furthermore, the results show that the percentage of SLPs in Portugal using NSOMEs is similar to those found in the USA, UK, Canada, and India, but different from those in Australia and Ireland.

Effect of swirling flow and particle-release pattern on drug delivery to human tracheobronchial airways.

The present study aims to investigate the effect of swirling flow on particle deposition in a realistic human airway. A computational fluid dynamic (CFD) model was utilized for the simulation of oral inhalation and particle transport patterns, considering the k-ω turbulence model. Lagrangian particle tracking was used to track the particles' trajectories. A normal breathing condition (30 L/min) was applied, and two-micron particles were injected into the mouth, considering swirling flow to the oral inhalation airflow. Different cases were considered for releasing the particles, which evaluated the impacts of various parameters on the deposition efficiency (DE), including the swirl intensity, injection location and pattern of the particle. The work's novelty is applying several injection locations and diameters simultaneously. The results show that the swirling flow enhances the particle deposition efficiency (20-40%) versus no-swirl flow, especially in the mouth. However, releasing particles inside the mouth, or injecting them randomly with a smaller injection diameter (dinj) reduced DE in swirling flow condition, about 50 to 80%. Injecting particles inside the mouth can decrease DE by about 20%, and releasing particles with smaller dinj leads to 50% less DE in swirling flow. In conclusion, it is indicated that the airflow condition is an important parameter for a reliable drug delivery, and it is more beneficial to keep the inflow uniform and avoid swirling flow.

Interactions between probiotic and oral pathogenic strains.

More than 6 billion bacteria and other microorganisms live in the adult oral cavity. As a result of any deleterious effect on this community, some microorganisms will survive better than others, which may trigger pathogenic processes like caries, halitosis, gingivitis or periodontitis. Oral dysbiosis is among the most frequent human health hazards globally. Quality of life of patients deteriorates notably, while treatments are often unpleasant, expensive and irreversible, e.g. tooth loss. In the experiments reported here, we investigated the individual interactions between 8 pathogenic and 8 probiotic strains and a commercially available probiotic product. Almost all pathogens, namely Fusobacterium nucleatum, Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Streptococcus mutans, Streptococcus oralis, Streptococcus gordonii, Enterococcus faecalis and Prevotella buccae are pathogens frequently occurring in the oral cavity. The used probiotic strains were Lactobacillus plantarum, Lactobacillus rhamnosus, Lactobacillus casei, Lactobacillus acidophilus, Lactobacillus delbrueckii, Bifidobacterium thermophilum and two Streptococcus dentisani isolates. Using a modified agar diffusion method, we investigated capability of the probiotic bacteria to prevent the growth of the pathogenic ones in order to identify candidates for future therapeutic treatments. The results indicated successful bacteriocin production, i.e. growth inhibition, against every pathogenic bacterium by at least 5 probiotic strains.

Variability in expiratory trajectory angles during consonant production by one human subject and from a physical mouth model: Application to respiratory droplet emission.

The COVID-19 pandemic has highlighted the need to improve understanding of droplet transport during expiratory emissions. While historical emphasis has been placed on violent events such as coughing and sneezing, the recognition of asymptomatic and presymptomatic spread has identified the need to consider other modalities, such as speaking. Accurate prediction of infection risk produced by speaking requires knowledge of both the droplet size distributions that are produced, as well as the expiratory flow fields that transport the droplets into the surroundings. This work demonstrates that the expiratory flow field produced by consonant productions is highly unsteady, exhibiting extremely broad inter- and intra-consonant variability, with mean ejection angles varying from ≈+30° to -30°. Furthermore, implementation of a physical mouth model to quantify the expiratory flow fields for fricative pronunciation of [f] and [θ] demonstrates that flow velocities at the lips are higher than previously predicted, reaching 20-30 m/s, and that the resultant trajectories are unstable. Because both large and small droplet transport are directly influenced by the magnitude and trajectory of the expirated air stream, these findings indicate that prior investigations of the flow dynamics during speech have largely underestimated the fluid penetration distances that can be achieved for particular consonant utterances.

Engaging a polylactide copolymer in oral tissue regeneration: first validation of Suprathel® for guided epithelial and osseous healing.

The present study investigated the capacity of Suprathel® (a copolymer membrane, so far validated for skin regeneration) to also regenerate oral tissue - mucosa and bone, by comparing this biomaterial, in a split-mouth rabbit model, to Mucoderm®, a xenogeneic collagen matrix certified for keratinized oral mucosa healing. The clinical reason behind this experimental animal model was to determine whether the benefits of this advanced skin regeneration product (Suprathel®) could be conveyed for future evaluation in clinical trials of oral tissue regeneration in humans. The outcomes of this study validated the use of Suprathel®, a terpolymer of polylactide with trimethylene carbonate and ε-caprolactone, for stimulation of oral epithelium and alveolar bone regeneration in rabbits. Both Suprathel® and Mucoderm® exhibited comparable results and the null hypothesis stating a comparable regenerating effect of these two materials could not be rejected.

Acute and Chronic Pain from Facial Skin and Oral Mucosa: Unique Neurobiology and Challenging Treatment.

The oral cavity is a portal into the digestive system, which exhibits unique sensory properties. Like facial skin, the oral mucosa needs to be exquisitely sensitive and selective, in order to detect harmful toxins versus edible food. Chemosensation and somatosensation by multiple receptors, including transient receptor potential channels, are well-developed to meet these needs. In contrast to facial skin, however, the oral mucosa rarely exhibits itch responses. Like the gut, the oral cavity performs mechanical and chemical digestion. Therefore, the oral mucosa needs to be insensitive, to some degree, in order to endure noxious irritation. Persistent pain from the oral mucosa is often due to ulcers, involving both tissue injury and infection. Trigeminal nerve injury and trigeminal neuralgia produce intractable pain in the orofacial skin and the oral mucosa, through mechanisms distinct from those seen in the spinal area, which is particularly difficult to predict or treat. The diagnosis and treatment of idiopathic chronic pain, such as atypical odontalgia (idiopathic painful trigeminal neuropathy or post-traumatic trigeminal neuropathy) and burning mouth syndrome, remain especially challenging. The central integration of gustatory inputs might modulate chronic oral and facial pain. A lack of pain in chronic inflammation inside the oral cavity, such as chronic periodontitis, involves the specialized functioning of oral bacteria. A more detailed understanding of the unique neurobiology of pain from the orofacial skin and the oral mucosa should help us develop novel methods for better treating persistent orofacial pain.

Learning to cricket hunt by the laboratory mouse (Mus musculus): Skilled movements of the hands and mouth in cricket capture and consumption.

Although the mouse (Mus musculus) is preyed upon by many other species of animals, it is also a predator and will hunt and consume crickets. There has been no previous description of how mice learn to hunt and no report on the extent to which they use their hands and mouth to assist prey capture and these were the objectives of the present study. Mice given one cricket each day displayed decreasing hunt times over 25-days for three phases of a hunt: investigate, in which a mouse explored and periodically encounter a cricket and often bit at it; pursue, in which a mouse's approach remained focused on the cricket until it was captured; and consume, in which the cricket was handled, decapitated, its core eaten, with its shell discarded. Although visual and auditory cues may contribute to locating a cricket, the vibrissae appeared to provide guidance in pursuit and capture when the cricket and mouse were proximate. Cricket capture involved extensive collaborative use of the mouth and the hands and mice could initiate capture with either the mouth or hands. Handling to eat involved manipulating the cricket into a head-up, ventrum-in position for decapitation and selective eating of the core of the cricket. The results are discussed in relation to mouse learning of a complex natural behavior, the use of tactile cues in the species-specific behavior of predation, and the contributions of the hands and mouth to predation.