Cortical processing of flexible and context-dependent sensorimotor sequences.

The brain generates complex sequences of movements that can be flexibly configured based on behavioural context or real-time sensory feedback1, but how this occurs is not fully understood. Here we developed a 'sequence licking' task in which mice directed their tongue to a target that moved through a series of locations. Mice could rapidly branch the sequence online based on tactile feedback. Closed-loop optogenetics and electrophysiology revealed that the tongue and jaw regions of the primary somatosensory (S1TJ) and motor (M1TJ) cortices2 encoded and controlled tongue kinematics at the level of individual licks. By contrast, the tongue 'premotor' (anterolateral motor) cortex3-10 encoded latent variables including intended lick angle, sequence identity and progress towards the reward that marked successful sequence execution. Movement-nonspecific sequence branching signals occurred in the anterolateral motor cortex and M1TJ. Our results reveal a set of key cortical areas for flexible and context-informed sequence generation.

Honey bees switch mechanisms to drink deep nectar efficiently.

The feeding mechanisms of animals constrain the spectrum of resources that they can exploit profitably. For floral nectar eaters, both corolla depth and nectar properties have marked influence on foraging choices. We report the multiple strategies used by honey bees to efficiently extract nectar at the range of sugar concentrations and corolla depths they face in nature. Honey bees can collect nectar by dipping their hairy tongues or capillary loading when lapping it, or they can attach the tongue to the wall of long corollas and directly suck the nectar along the tongue sides. The honey bee feeding apparatus is unveiled as a multifunctional tool that can switch between lapping and sucking nectar according to the instantaneous ingesting efficiency, which is determined by the interplay of nectar-mouth distance and sugar concentration. These versatile feeding mechanisms allow honey bees to extract nectar efficiently from a wider range of floral resources than previously appreciated and endow them with remarkable adaptability to diverse foraging environments.

ISL1/SHH/CXCL12 signaling regulates myogenic cell migration during mouse tongue development.

Migration of myoblasts derived from the occipital somites is essential for tongue morphogenesis. However, the molecular mechanisms of myoblast migration remain elusive. In this study, we report that deletion of Isl1 in the mouse mandibular epithelium leads to aglossia due to myoblast migration defects. Isl1 regulates the expression pattern of chemokine ligand 12 (Cxcl12) in the first branchial arch through the Shh/Wnt5a cascade. Cxcl12+ mesenchymal cells in Isl1ShhCre embryos were unable to migrate to the distal region, but instead clustered in a relatively small proximal domain of the mandible. CXCL12 serves as a bidirectional cue for myoblasts expressing its receptor CXCR4 in a concentration-dependent manner, attracting Cxcr4+ myoblast invasion at low concentrations but repelling at high concentrations. The accumulation of Cxcl12+ mesenchymal cells resulted in high local concentrations of CXCL12, which prevented Cxcr4+ myoblast invasion. Furthermore, transgenic activation of Ihh alleviated defects in tongue development and rescued myoblast migration, confirming the functional involvement of Hedgehog signaling in tongue development. In summary, this study provides the first line of genetic evidence that the ISL1/SHH/CXCL12 axis regulates myoblast migration during tongue development.

The transcription factors Foxf1 and Foxf2 integrate the SHH, HGF and TGFß signaling pathways to drive tongue organogenesis.

The tongue is a highly specialized muscular organ with diverse cellular origins, which provides an excellent model for understanding mechanisms controlling tissue-tissue interactions during organogenesis. Previous studies showed that SHH signaling is required for tongue morphogenesis and tongue muscle organization, but little is known about the underlying mechanisms. Here we demonstrate that the Foxf1/Foxf2 transcription factors act in the cranial neural crest cell (CNCC)-derived mandibular mesenchyme to control myoblast migration into the tongue primordium during tongue initiation, and thereafter continue to regulate intrinsic tongue muscle assembly and lingual tendon formation. We performed chromatin immunoprecipitation sequencing analysis and identified Hgf, Tgfb2 and Tgfb3 among the target genes of Foxf2 in the embryonic tongue. Through genetic analyses of mice with CNCC-specific inactivation of Smo or both Foxf1 and Foxf2, we show that Foxf1 and Foxf2 mediate hedgehog signaling-mediated regulation of myoblast migration during tongue initiation and intrinsic tongue muscle formation by regulating the activation of the HGF and TGFß signaling pathways. These data uncover the molecular network integrating the SHH, HGF and TGFß signaling pathways in regulating tongue organogenesis.

Polysomnographic airflow shapes and site of collapse during drug-induced sleep endoscopy.

BACKGROUND: Differences in the pharyngeal site of collapse influence efficacy of non-continuous positive airway pressure therapies for obstructive sleep apnoea (OSA). Notably, complete concentric collapse at the level of the palate (CCCp) during drug-induced sleep endoscopy (DISE) is associated with reduced efficacy of hypoglossal nerve stimulation, but CCCp is currently not recognisable using polysomnography. Here we develop a means to estimate DISE-based site of collapse using overnight polysomnography. METHODS: 182 OSA patients provided DISE and polysomnography data. Six polysomnographic flow shape characteristics (mean during hypopnoeas) were identified as candidate predictors of CCCp (primary outcome variable, n=44/182), including inspiratory skewness and inspiratory scoopiness. Multivariable logistic regression combined the six characteristics to predict clear presence (n=22) versus absence (n=128) of CCCp (partial collapse and concurrent tongue base collapse excluded). Odds ratios for actual CCCp between predicted subgroups were quantified after cross-validation. Secondary analyses examined complete lateral wall, tongue base or epiglottis collapse. External validation was performed on a separate dataset (ntotal=466). RESULTS: CCCp was characterised by greater scoopiness (ß=1.5±0.6 per 2sd, multivariable estimate±se) and skewness (ß=11.4±2.4) compared with non-CCCp. The odds ratio for CCCp in predicted positive versus negative subgroups was 5.0 (95% CI 1.9-13.1). The same characteristics provided significant cross-validated prediction of lateral wall (OR 6.3, 95% CI 2.4-16.5), tongue base (OR 3.2, 95% CI 1.4-7.3) and epiglottis (OR 4.4, 95% CI 1.5-12.4) collapse. CCCp and lateral wall collapse shared similar characteristics (skewed, scoopy), diametrically opposed to tongue base and epiglottis collapse characteristics. External validation confirmed model prediction. CONCLUSIONS: The current study provides a means to recognise patients with likely CCCp or other DISE-based site of collapse categories using routine polysomnography. Since site of collapse influences therapeutic responses, polysomnographic airflow shape analysis could facilitate precision site-specific OSA interventions.

Association between swallowing dynamics, tongue pressure and pulmonary function in patients with idiopathic pulmonary fibrosis.

BACKGROUND: Swallowing is a complex process that requires the coordination of muscles in the mouth, pharynx, larynx, and esophagus. Dysphagia occurs when a person has difficulty swallowing. In the case of subjects with respiratory diseases, the presence of oropharyngeal dysphagia potentially increases lung disease exacerbations, which can lead to a rapid decline in lung function. This study aimed to analyze the swallowing of patients with idiopathic pulmonary fibrosis (IPF). METHODS: Patients with IPF were evaluated using the Eating Assessment Tool (EAT-10), tongue pressure, the Timed Water Swallow Test (TWST), and the Test of Mastication and Swallowing Solids (TOMASS). The findings were related to dyspnea severity assessed by the modified Medical Research Counsil (mMRC) score; the nutritional status screened with Mini Nutritional Assessment (MNA) tool; and pulmonary function tests, specifically spirometry and measurement of the diffusing capacity for carbon monoxide (DLCO), the maximal inspiratory pressure (PImax), and the maximal expiratory pressure (PEmax). RESULTS: The sample consisted of 34 individuals with IPF. Those who exhibited swallowing modifications scored lower on the MNA than those who did not (9.6 ± 0.76 vs. 11.64 ± 0.41 points; mean difference 1.98 ± 0.81 points; p = 0.02). They also showed poorer lung function when considering the predicted force vital capacity (FVC; 81.5% ± 4.61% vs. 61.87% ± 8.48%; mean difference 19.63% ± 9.02%; p = 0.03). The speed of liquid swallowing was altered in 31of 34 of the evaluated subjects (91.1%). The number of liquid swallows correlated significantly with the forced expiratory volume in 1 s (FEV1)/FVC ratio (r = 0.3; p = 0.02). Solid eating and swallowing assessed with the TOMASS score correlated with lung function. The number of chewing cycles correlated negatively with PImax% predicted (r = -0.4; p = 0.0008) and PEmax% predicted (r = -0.3; p = 0.02). FVC% predicted correlated with increased solid swallowing time (r = -0.3; p = 0.02; power = 0.6). Swallowing solids was also impacted by dyspnea. CONCLUSION: Patients with mild-to-moderate IPF can present feeding adaptations, which can be related to the nutritional status, lung function, and the severity of dyspnea.

Neural indicators of articulator-specific sensorimotor influences on infant speech perception.

While there is increasing acceptance that even young infants detect correspondences between heard and seen speech, the common view is that oral-motor movements related to speech production cannot influence speech perception until infants begin to babble or speak. We investigated the extent of multimodal speech influences on auditory speech perception in prebabbling infants who have limited speech-like oral-motor repertoires. We used event-related potentials (ERPs) to examine how sensorimotor influences to the infant's own articulatory movements impact auditory speech perception in 3-mo-old infants. In experiment 1, there were ERP discriminative responses to phonetic category changes across two phonetic contrasts (bilabial-dental /ba/-/ɗa/; dental-retroflex /ɗa/-/ɖa/) in a mismatch paradigm, indicating that infants auditorily discriminated both contrasts. In experiment 2, inhibiting infants' own tongue-tip movements had a disruptive influence on the early ERP discriminative response to the /ɗa/-/ɖa/ contrast only. The same articulatory inhibition had contrasting effects on the perception of the /ba/-/ɗa/ contrast, which requires different articulators (the lips vs. the tongue) during production, and the /ɗa/-/ɖa/ contrast, whereby both phones require tongue-tip movement as a place of articulation. This articulatory distinction between the two contrasts plausibly accounts for the distinct influence of tongue-tip suppression on the neural responses to phonetic category change perception in definitively prebabbling, 3-mo-old, infants. The results showing a specificity in the relation between oral-motor inhibition and phonetic speech discrimination suggest a surprisingly early mapping between auditory and motor speech representation already in prebabbling infants.

Anatomical and Surface Electron Microscopic Investigation of the Tongue and Laryngeal Prominence in the Red-Eyed Turtle Dove (Streptopelia semitorquata, Rüppel 1837).

This study investigated the morphology of tongue and laryngeal structures in red-eyed dove and related it to feeding habits. Samples were examined using gross anatomy, scanning electron microscopy (SEM), and histological techniques. The tongue conformed to the shape of the lower beak, and the apex with a pointed tip, body, and root were distinguished. A median grove was apparent, and a papillary crest with pointed triangular papillae separated the body from the root. The length of the tongue, its width (body), and the percentage of the length of the lower jaw occupied by the tongue were, on average, 12.5 mm, 2.3 mm, and 57.3%, respectively. SEM showed highly desquamated dorsal epithelium with pointed papillae-like projections. The papillary crest presented pointed papillae of about 20-22. Salivary openings were apparent in the root, surrounded by mucosal folds and blunt papillae. Laryngeal prominence was irregularly triangular shaped and elevated. The rim of the glottis showed glandular pinpointed marks. Typical cornified multilayered mucosal epithelium was present in the apex and decreased caudally. Hyaline entoglossal cartilage and adjoining connective tissue were present in the body and apex. Numerous tubuloalveolar glands were seen in the body and root. The rim of the glottis showed mucous intraepithelial glands. The rostral and caudal lingual glands indicated positive reaction to neutral and acidic mucins. This study demonstrated a morphofunctional relationship of the tongue of a red-eyed dove to its diet.

The tongue microbiome of young patients with chronic kidney disease and their healthy mothers.

OBJECTIVES: Oral microbiome plays a crucial role in the incidence and development of oral diseases. An altered intestinal microbiome has been reported in adults with chronic kidney disease (CKD). This study aimed to characterize the tongue microbiome of young patients with CKD compared to their healthy mothers to identify the influence of CKD-associated factors on resilient tongue ecosystem. MATERIAL AND METHODS: Thirty patients with CKD (mean age, 14.2 years; 16 males and 14 females) and generalized gingivitis were included in the study. Swabs of the posterior tongue were collected from the patients and 21 mothers (mean age 40.8 years). Next-generation sequencing of 16S rDNA genes was employed to quantitatively characterize microbial communities. RESULTS: The bacterial communities were similar in terms of richness and diversity between patients and mothers (p > 0.05). In patients with CKD, 5 core phyla, 20 core genera, and 12 core species were identified. CONCLUSIONS: The tongue microbiome of the study participants showed no relevant CKD-associated differences compared to their mothers and appears to be a highly preserved niche in the oral cavity. Differences observed in the abundance of individual species in this study could be attributed to the age rather than CKD, even after a mean disease duration of 11 years. CLINICAL RELEVANCE: CKD and its associated metabolic changes appear to have no detectable impact on the resilient tongue microbiome observed in young patients.

Correlation between oral muscle pressure and malocclusion in mixed dentition: a cross-sectional study.

OBJECTIVE: To investigate the relationship between oral muscle pressure and malocclusion in the mixed dentition. MATERIALS AND METHODS: Maximum tongue, lip and cheek pressure was measured using the Iowa Oral Performance Instrument (IOPI) in 3 patient cohorts: patients with (1) posterior crossbite, (2) class II relationship and (3) a control group of patients without malocclusion. Linear models were used to compare the mean differences in muscle pressure between groups, with correction for age and gender. The imbalance between lips and tongue and between lips and cheeks was calculated by the Delta z-scores of each group. RESULTS: A total of 146 participants were included, 46 (mean age 8.71±0.85), 41 (mean age 11.74±1.17) and 35 (mean age 10.71±1.92) in groups 1, 2 and 3 respectively. Patients with malocclusion showed significantly higher lip and lower cheek pressure and imbalance favouring the lips over the tongue compared to controls. Class II,1 patients showed significantly higher tongue pressure than Class II,2. No differences were found in muscle pressure or imbalance between crossbite and Class II nor between crossbite types. CONCLUSION AND CLINICAL RELEVANCE: These findings suggest that oral muscle pressure may be associated with malocclusion. This highlights the importance of functional diagnosis and its implications on the prevention and treatment of malocclusion, as well as on orthodontic stability.

The effect of tongue reduction for preventing adverse effects in patients undergoing class III orthognathic surgery: a three-dimensional comparative analysis.

OBJECTIVES: This study aims to evaluate the potential benefits of combining tongue reduction with mandibular setback surgery in patients undergoing class III orthognathic surgery. Specifically, we investigated whether this combined approach reduced the risk of surgical relapse, condylar resorption, and airway space reduction by mitigating tongue pressure on the mandible. MATERIAL AND METHODS: The study retrospectively enrolled patients who had undergone bilateral sagittal split ramus osteotomy (BSSRO) with at least 5 mm of setback and met the criteria of a body mass index > 20 kg/m2 and tongue volume > 100 mm3. The study included 20 patients with 10 in the tongue reduction group (TR, n = 10) and 10 in the BSSRO only group (SO, n = 10). RESULTS: The volumetric changes of the total airway space were significantly different between the TR and SO groups (p = 0.028). However, no significant differences were observed in the condylar resorption and postoperative relapse between the groups (p = 0.927 and 0.913, respectively). The difference between the resorption of the anterior and posterior segments of the condyle was also statistically insignificant (p = 0.826). Postoperative counterclockwise rotation of the proximal segment only demonstrated a significant correlation with postoperative relapse (p = 0.048). CONCLUSIONS: The reduction in tongue volume demonstrated a preventive effect on the reduction of the airway space after mandibular setback, although it did not yield statistical significance concerning surgical relapse and condylar volume. The counterclockwise rotation of the proximal segment might be responsible for the forward displacement of the distal segment and postoperative relapse. However, the clinical implications of this finding should be interpreted with caution owing to the limited sample size CLINICAL RELEVANCE: Tongue reduction could potentially serve as a preventive measure in preserving the airway space and might be beneficial in mitigating the risk of obstructive sleep apnea in patients with class III deformity.

Thermal Imaging of the Tongue Surface as a Predictive Method in the Diagnosis of Type 2 Diabetes Mellitus.

Over the past 20 years, the high prevalence of diabetes has become a global public health problem. BACKGROUND: The objective of this study was to develop a non-invasive screening method for diabetes which will enable the detection of the disease at an early stage. METHODS: This study included 63 adult patients of both sexes: 30 patients with type 2 diabetes (t2DM) and 33 healthy volunteers. The temperature distribution on the tongue's dorsum and apex surface was studied in patients after a mouth-cooling procedure had been introduced. The study used an FLIR T540 thermal imaging camera. An analysis of the correlation between the ∆T values of the tongue dorsum and apex and the glycated hemoglobin (HbA1c) level was performed. RESULTS: The median of the average dorsum temperature measured 10 min after mouth rinsing was almost 0.8 [°C] lower than for healthy individuals. Also, studies showed a positive average correlation with a Pearson coefficient of r = 0.46 between the HbA1c level and the ∆T of the tongue dorsum. CONCLUSIONS: Tongue temperature measured using the IRT showed a correlation with standard biochemical parameters; it may also differentiate patients and constitute a specific screening method for patients with t2DM.

Relationship between maximal isometric tongue pressure and limit of fracture force of gels in tongue squeezing.

BACKGROUND: There is no clear objective indicator for selecting soft foods that are required for food bolus formation in older people with impaired oral function. OBJECTIVE: This study aimed to investigate the relationship between maximal isometric tongue pressure (MITP) and the mechanical properties of gels that can be crushed by the tongue. METHODS: This study included 65 healthy participants aged 22-96 (young group; 15 males, 15 females; older dentate group; 7 males, 8 females; older edentulous group; 10 males, 10 females). MITP was measured by the balloon-probe device. Agar gel with 10 different kinds of fracture force from 10N to 100N was used. The limit of fracture force of gels (LFFG) that were crushed by the tongue was measured by the up-and-down method. In the older edentulous group, two items were measured with and without dentures. Spearman's rank correlation coefficient was used to evaluate the relationship between MITP and LFFG in each group (p < .05). RESULTS: There were positive correlations between MITP and LFFG in all groups (overall groups: rs = .66, young group: rs = .46, older dentate group: rs = .61, older edentulous group with dentures: rs = .60, older edentulous group without dentures: rs = .47). CONCLUSION: MITP and LFFG were positively correlated in young, older dentate and older edentulous groups, suggesting that MITP has the potential to be an objective indicator of the range of mechanical properties of soft food that can be crushed by the tongue.

Relationship between texture perception and oral function: A preliminary study in young, healthy adults.

BACKGROUND: Oral frailty, characterised by reduced oral function, is associated with systemic health issues in older adults. Although the criteria for diminished oral function often focus on motor and secretory abilities, texture perception also plays a crucial role in health due to its impact on food intake and palatability. OBJECTIVE: This study aimed to explore the relationship between thickness discrimination ability (TDA) and oral motor and secretory functions in healthy young individuals. METHODS: Twenty-eight adults were assessed for texture perception using eight concentrations of aqueous xanthan gum solutions to determine TDA scores. Measurements of occlusal force, masticatory performance, tongue pressure, stimulated salivary flow rate and tongue-lip motor function were conducted. Spearman's correlation analysis was used to evaluate the relationship between TDA scores and oral functions. Participants were divided into high-sensitivity and low-sensitivity groups based on their TDA scores to compare oral function test results. RESULTS: The TDA scores varied among the participants, with higher scores correlating with higher masticatory performance (r = 0.41, p < .05). Masticatory performance in the high-sensitivity group was significantly higher than in the low-sensitivity group (211.9 ± 59.2 mg/dL vs. 157.9 ± 43.0 mg/dL, p = .013), with no significant differences in other oral functions. CONCLUSION: Masticatory performance was correlated with TDA, suggesting a link between the selection function of mastication and thickness discrimination. These findings highlight the potential relevance of texture perception in oral function and indicate the need for further exploration, particularly in older adults with declining oral health.

Factors associated with the oral health status of patients with schizophrenia: A cross-sectional study.

BACKGROUND: Oral function deterioration attributed to ageing and medications is one of the main contributory factors of dysphagia. Therefore, oral health management is essential in older patients with schizophrenia. However, no previous studies have evaluated the oral function in patients with schizophrenia. OBJECTIVE: We surveyed patients with schizophrenia to identify factors associated with ageing-related variations in oral function. METHODS: This cross-sectional study included 34 male patients diagnosed with schizophrenia who were hospitalised at a psychiatric hospital between July and September 2021 and underwent a screening examination during dental care. The survey items included basic information, oral hygiene information, oral (oral diadochokinesis [ODK] and tongue pressure), physical function, and nutritional status. Thirty-six male community-dwelling older individuals were included as controls, and their outcomes were compared with those of patients with schizophrenia. RESULTS: Compared with healthy older adults, patients with schizophrenia demonstrated significantly lower teeth numbers, ODK, and calf circumference (CC) (p < .05). Multiple regression analysis revealed that ODK was associated with age and schizophrenia (p < .05). Conversely, tongue pressure was associated with CC (p < .05), suggesting different factors' association with the parameters indicating decreased oral function. CONCLUSIONS: Our study findings suggest that older patients with schizophrenia have decreased tongue pressure and generalised muscle mass, highlighting the need to manage oral function. Interventions for tongue pressure were more strongly associated with muscle mass and could be easier to manage than those with disease-dependent changes in ODK. TRIAL REGISTRATION: Retrospectively registered.

Tongue pressure and maxillofacial muscle activities during swallowing in patients with mandibular prognathism.

BACKGROUND: Coordination among lip, cheek and tongue movements during swallowing in patients with mandibular prognathism remains unclear. OBJECTIVES: This study aimed to identify the temporal sequences of tongue pressure and maxillofacial muscle activities during swallowing in patients with mandibular prognathism and compared characteristics with those of healthy volunteers. METHODS: Seven patients with mandibular prognathism (mandibular prognathism group) and 25 healthy volunteers with individual normal occlusion (control group) were recruited. Tongue pressures and masseter, orbicularis oris, mentalis and supra- and infrahyoid muscle activities while swallowing gel were measured simultaneously using a sensor sheet system with five measurement points and surface electromyography, respectively. Onset time, offset time and durations of tongue pressure and muscle activities were analysed. RESULTS: In the mandibular prognathism group, tongue pressure was often produced first in more peripheral parts of the palate. Offset of tongue pressure in the posteromedian and peripheral parts of the palate and maxillofacial muscle activities except for orbicularis oris were delayed. Duration of tongue pressure in the anteromedian part of the palate was significantly shorter and durations of masseter, mentalis and suprahyoid muscle activities were significantly longer. Times to onset of orbicularis oris and suprahyoid muscle activities based on first onset of tongue pressure were significantly shorter. CONCLUSION: These results suggest that patients with mandibular prognathism may exhibit specific patterns of tongue pressure production and maxillofacial muscle activities during swallowing.

A mandibular advancement device attenuates the abnormal morphology and function of mitochondria from the genioglossus in obstructive sleep apnea-hypopnea syndrome rabbits.

BACKGROUND: Obstructive sleep apnea hypopnea syndrome (OSAHS) is a serious and potentially life-threatening disease. Mandibular advancement device (MAD) has the characteristics of non-invasive, comfortable, portable and low-cost, making it the preferred treatment for mild-to-moderate OSAHS. Our previous studies found that abnormal contractility and fibre type distribution of the genioglossus could be caused by OSAHS. However, whether the mitochondria participate in these tissue changes is unclear. The effect of MAD treatment on the mitochondria of the genioglossus in OSAHS is also uncertain. OBJECTIVE: To examine the morphology and function of mitochondria from the genioglossus in a rabbit model of obstructive sleep apnea-hypopnea syndrome (OSAHS), as well as these factors after insertion of a mandibular advancement device (MAD). METHODS: Thirty male New Zealand white rabbits were randomised into three groups: control, OSAHS and MAD, with 10 rabbits in each group. Animals in Group OSAHS and Group MAD were induced to develop OSAHS by injection of gel into the submucosal muscular layer of the soft palate. The rabbits in Group MAD were fitted with a MAD. The animals in the control group were not treated. Further, polysomnography (PSG) and cone-beam computed tomography (CBCT) scan were used to measure MAD effectiveness. CBCT of the upper airway and PSG suggested that MAD was effective. Rabbits in the three groups were induced to sleep for 4-6 h per day for eight consecutive weeks. The genioglossus was harvested and detected by optical microscopy and transmission electron microscopy. The mitochondrial membrane potential was determined by laser confocal microscopy and flow cytometry. Mitochondrial complex I and IV activities were detected by mitochondrial complex assay kits. RESULTS: OSAHS-like symptoms were induced successfully in Group OSAHS and rescued by MAD treatment. The relative values of the mitochondrial membrane potential, mitochondrial complex I activity and complex IV activity were significantly lower in Group OSAHS than in the control group; however, there was no significant difference between Group MAD and the control group. The OSAHS-induced injury and the dysfunctional mitochondria of the genioglossus muscle were reduced by MAD treatment. CONCLUSION: Damaged mitochondrial structure and function were induced by OSAHS and could be attenuated by MAD treatment.

Influence of oral motor tasks on postural muscle activity during dynamic reactive balance.

BACKGROUND: Jaw clenching improves dynamic reactive balance on an oscillating platform during forward acceleration and is associated with decreased mean sway speed of different body regions. OBJECTIVE: It is suggested that jaw clenching as a concurrent muscle activity facilitates human motor excitability, increasing the neural drive to distal muscles. The underlying mechanism behind this phenomenon was studied based on leg and trunk muscle activity (iEMG) and co-contraction ratio (CCR). METHODS: Forty-eight physically active and healthy adults were assigned to three groups, performing three oral motor tasks (jaw clenching, tongue pressing against the palate or habitual lower jaw position) during a dynamic one-legged stance reactive balance task on an oscillating platform. The iEMG and CCR of posture-relevant muscles and muscle pairs were analysed during platform forward acceleration. RESULTS: Tongue pressing caused an adjustment of co-contraction patterns of distal muscle groups based on changes in biomechanical coupling between the head and trunk during static balancing at the beginning of the experiment. Neither iEMG nor CCR measurement helped detect a general neuromuscular effect of jaw clenching on the dynamic reactive balance. CONCLUSION: The findings might indicate the existence of robust fixed patterns of rapid postural responses during the important initial phases of balance recovery.

Low tongue pressure and depression using Kihon Checklist for assessing frailty status among community-dwelling Japanese older adults: A pilot study.

BACKGROUND: Evaluation of low tongue pressure is used to diagnose oral hypofunction. The pathophysiology of oral hypofunction is hypothesized to be associated with oral dysfunction related to ageing. Depression in older adults is a major problem and is related to handgrip strength, which is related to tongue pressure. We hypothesized that low tongue pressure could indicate depression mood in community-dwelling older adults. OBJECTIVES: This study aimed to measure maximum tongue pressure and compare it to the responses to the Kihon Checklist (KCL), which is used to check mental and physical deterioration of community-dwelling older adults. METHODS: A total of 49 community-dwelling independent older adults with stable dental condition (23 men, 26 women; median age, 79 years) answered the KCL, which contained questions on frailty status, cognitive function, nutritional and sarcopenia status. Oral function was measured to assess oral hypofunction. The relationship between tongue pressure differences and frailty status, cognitive function, nutritional and sarcopenia status was analysed using logistic regression analyses after adjusting for age and sex. RESULTS: Nine participants (6 men and 3 women; median age, 81 years) had a tongue pressure <23.0 kPa, which was the lowest limit of the standard value of maximum tongue pressure in patients aged ≥70 years. Logistic regression analyses showed that only Question 21, which is related to a lack of fulfilment in daily life, was significantly associated with low tongue pressure (p = .027). CONCLUSION: Low tongue pressure may be associated with sociopsychological factors in older adults.

Improvement of oral function and its impact on oral food intake in subacute stroke patients: A prospective study with dental intervention.

BACKGROUND: The association between oral food intake and oral function during the subacute stage of stroke is not well known. OBJECTIVE: To investigate (1) oral function changes in subacute stroke patients and (2) association between oral function and oral intake status at several time points. METHODS: In a prospective study involving 324 stroke patients at a convalescent rehabilitation unit, four oral function parameters (maximum tongue pressure, MTP; lip-tongue motor function, LTMF; maximum occlusal force, MOF and oral health assessment tool, OHAT) were quantitatively measured upon admission (T0), at 1 month (T1) and 2 months (T2). Oral feeding status was assessed using the Functional Oral Intake Scale (FOIS) and divided based on the FOIS score into the dysphagic and regular diet groups. The changes in oral functions at the three time points were tested using generalized estimating equation analysis. The association between FOIS groups and oral functions at T1 and T2 was analysed by means of logistic regression analysis. RESULTS: All oral function parameters improved significantly over time during the hospital stay (mean differences: 4.9 for MTP, 0.6 for LTMF, 1.1 for MOF and -1.8 for OHAT). The FOIS groups were significantly associated with MTP (p < .05) and OHAT (p < .05) at both T1 and T2. CONCLUSION: Our findings suggest that oral function significantly improves in patients during subacute stroke rehabilitation and better oral health can be associated with better oral intake. Improved oral function through dental intervention and oral rehabilitation may contribute to gains in oral food intake.