Tongue movements in feeding and speech

Masticatory simulators based on oral physiology in food research: A systematic review

A masticatory simulator is a mechanical device that mimics the physiological structures of the human oral cavity, chewing movement system, and functions. The advantage of this device lies in real-time tracking and analysis of food boluses within a sealed oral space, offering a direct validation platform for food experiments without constraints related to time, space, and individual variations. The degree to which the masticatory simulator simulates physiological structures reflects its efficacy in replicating oral physiological processes. This review mainly discusses the physiological structures of the oral cavity, the simulation of biomimetic components, and the development, feasibility assessment, applications, and prospects of masticatory simulators in food. The highlight of this review is the analogy of biomimetic component designs in masticatory simulators over the past 15 years. It summarizes the limitations of masticatory simulators and their biomimetic components, proposing potential directions for future development. The purpose of this review is to assist readers in understanding the research progress and latest literature findings on masticatory simulators while also offering insights into the design and innovation of masticatory simulators.

Basic characteristics of tongue pressure and electromyography generated by articulation of a syllable using the posterior part of the tongue

The basic function of the tongue in pronouncing diadochokinesis and other syllables is not fully understood. This study investigates the influence of sound pressure levels and syllables on tongue pressure and muscle activity in 19 healthy adults (mean age: 28.2 years; range: 22-33 years). Tongue pressure and activity of the posterior tongue were measured using electromyography (EMG) when the velar stops /ka/, /ko/, /ga/, and /go/ were pronounced at 70, 60, 50, and 40 dB. Spearman's rank correlation revealed a significant, yet weak, positive association between tongue pressure and EMG activity (ρ = 0.14, p < 0.05). Mixed-effects model analysis showed that tongue pressure and EMG activity significantly increased at 70 dB compared to other sound pressure levels. While syllables did not significantly affect tongue pressure, the syllable /ko/ significantly increased EMG activity (coefficient = 0.048, p = 0.013). Although no significant differences in tongue pressure were observed for the velar stops /ka/, /ko/, /ga/, and /go/, it is suggested that articulation is achieved by altering the activity of both extrinsic and intrinsic tongue muscles. These findings highlight the importance of considering both tongue pressure and muscle activity when examining the physiological factors contributing to sound pressure levels during speech.

Posterior tongue tie: that is a thing?

PURPOSE OF REVIEW

The purpose of this review is to examine the current research of the posterior tongue tie and how it relates to breast feeding, solid feeding, and speech.

RECENT FINDINGS

Recent findings show that the posterior tongue tie may play a role in effective breast feeding.

SUMMARY

Ankyloglossia is the term used for the restriction of the movement of the tongue that impairs certain functions such as breastfeeding or bottle feeding, feeding with solids, and speech. Cadaver studies have shown that there can be a restriction of the tongue and oral tissues in some people relative to others. In some breast-feeding studies, releasing the posterior tie has been shown to improve certain aspects of tongue movement. There is little evidence for or against posterior tongue ties contributing to other problems such as speech and solid feeding. This article goes into depth about the current studies on posterior ankyloglossia.

Motion reconstruction and finite element analysis of the temporomandibular joint during swallowing in healthy adults

There is a close physiological connection between swallowing and the temporomandibular joint (TMJ). However, a shortage of quantitative research on the biomechanical behavior of the TMJ during swallowing exists. The purpose of this study was to reconstruct the movement of the temporomandibular joint (TMJ) based on in vivo experiment and analyze the biomechanical responses during swallowing in healthy adults to investigate the role of the TMJ in swallowing. Motion capture of swallowing, computed tomography (CT), and magnet resonance images (MRI) were performed on six healthy subjects. The movements of the TMJ during swallowing were reconstructed from the motion capture data. The three-dimensional finite element model was constructed. The dynamic finite element analysis of the swallowing process was performed based on the motion data. The range of condylar displacement was within 1 mm in all subjects. The left and right condyle movements were asymmetrical in two-thirds of the subjects. The peak stresses of the discs were relatively low, with a maximum of 0.11 MPa. During swallowing, the condylar displacement showed two trends: slow retraction and slow extension. The tendency to extend could lead to a gradual increase in stress on the disc.

Effects of oropharyngeal exercises on CPAP compliance: A prospective intervention study

PURPOSE

To investigate the effects of oropharyngeal exercise on continuous positive airway pressure (CPAP) compliance in patients with moderate to severe obstructive sleep apnea over a period of 6 months.

MATERIALS AND METHODS

This study was conducted as a prospective, observational, and interventional investigation. A total of 70 patients with moderate to severe obstructive sleep apnea were randomly assigned to either the oropharyngeal exercise group (n = 44) or the sham-therapy group (n = 26). The compliance of the enrolled patients with CPAP therapy was assessed at baseline, 3-month follow-up and 6-month follow-up. Objective sleep data, questionnaire and CPAP use time were collected over a half-year period (i.e., baseline, 6 months, and 12 months).

RESULTS

The study found that the average use time of CPAP within one month was significantly longer in the oropharyngeal exercises group compared to the sham-therapy group at the 3-month assessment (5.5 ± 1.2 vs 4.8 ± 1.3 h per night; p=0.030), and much significantly longer at 6-months assessment (6.0 ± 1.4 vs 4.9 ± 1.3 h per night; p=0.001). Furthermore, the average use time of CPAP increased over time, with the oropharyngeal exercises group exhibiting a more pronounced growth from baseline to the six-month follow-up (4.8 ± 1.0 h per night to 6.0 ± 1.3 h per night, p < 0.001) compared to the sham-therapy group (4.8 ± 1.3 h per night to 4.9 ± 1.3 h per night, p=0.952). Additionally, the oropharyngeal exercise group demonstrated an improvement in the Epworth sleepiness scale compared to the sham-therapy group at the 3-month follow-up (6.0 ± 2.0 vs 8.8 ± 3.2; p < 0.001), as well as decreased significantly at 6-month follow-up (p = 0.032).

CONCLUSIONS

CPAP adherence can be improved with oropharyngeal exercises therapy among moderate to severe OSA patients. Notably, the average duration of CPAP usage and reduction in daytime sleepiness were maintained even after six months of oropharyngeal exercise therapy.

A Review of In Vitro and In Silico Swallowing Simulators: Design and Applications

Swallowing is a primary and complex behaviour that transports food and drink from the oral cavity, through the pharynx and oesophagus, into the stomach at an appropriate rate and speed. To understand this sophisticated behaviour, a tremendous amount of research has been carried out by utilising the in vivo approach, which is often challenging to perform, poses a risk to the subjects if interventions are undertaken and are seldom able to control for confounding factors. In contrast, in silico (computational) and in vitro (instrumental) methods offer an alternate insight into the process of the human swallowing system. However, the appropriateness of the design and application of these methods have not been formally evaluated. The purpose of this review is to investigate and evaluate the state of the art of in vitro and in silico swallowing simulators, focusing on the evaluation of their mechanical or computational designs in comparison to the corresponding swallowing mechanisms during various phases of swallowing (oral phase, pharyngeal phase and esophageal phase). Additionally, the potential of the simulators is also discussed in various areas of applications, including the study of swallowing impairments, swallowing medications, food process design and dysphagia management. We also address current limitations and recommendations for the future development of existing simulators.

Wireless Mouth Motion Recognition System Based on EEG-EMG Sensors for Severe Speech Impairments

This study aims to demonstrate the feasibility of using a new wireless electroencephalography (EEG)-electromyography (EMG) wearable approach to generate characteristic EEG-EMG mixed patterns with mouth movements in order to detect distinct movement patterns for severe speech impairments. This paper describes a method for detecting mouth movement based on a new signal processing technology suitable for sensor integration and machine learning applications. This paper examines the relationship between the mouth motion and the brainwave in an effort to develop nonverbal interfacing for people who have lost the ability to communicate, such as people with paralysis. A set of experiments were conducted to assess the efficacy of the proposed method for feature selection. It was determined that the classification of mouth movements was meaningful. EEG-EMG signals were also collected during silent mouthing of phonemes. A few-shot neural network was trained to classify the phonemes from the EEG-EMG signals, yielding classification accuracy of 95%. This technique in data collection and processing bioelectrical signals for phoneme recognition proves a promising avenue for future communication aids.

Comparison of Speech Defects in Different Types of Malocclusion

Introduction Speech has a great impact on human evolution, allowing for the widespread knowledge and advancement of tools. Difficulty in pronouncing one or more sounds is the most common speech impairment. Speech defects are more commonly associated with class III malocclusion patients (difficulty in pronouncing 's' and 't' sounds), the second in line is class II malocclusion (difficulty in pronouncing 's' and 'z' sounds), and speech distortions are least affected in class I malocclusion (difficulty in pronouncing 's' and 'Sh'). Most patients with dentofacial disharmonies and speech distortions need orthodontic care and orthognathic surgery to resolve their issues with mastication, aesthetics, and speech. Aims and objectives To compare and assess speech difficulties in different types of malocclusion. Materials and methods The study was conducted over 160 subjects for three and half months. All of them were evaluated for speech defects before they received orthodontic treatment. The main basis of this study is according to Angle's classification of malocclusion. The subjects were segregated according to Angle's classification of malocclusion. Malocclusion traits that are included in this study are Angle's class I, Angle's class II division I and division II, and Angle's class III. Results According to the results, out of 160 subjects, labio-dental speech defects are observed in 8% where n=13 of the study participants, linguodental speech defects are observed in 2% where n=3, lingua-alveolar speech defects are present in 54% where n=86, and bilabial speech defects are observed in 2% where n=3 of the study participants. Here 'n' represents the frequency of the subjects. Severe speech defects are seen in Angle's class III malocclusion. Results according to the type of malocclusion include: labio-dental speech defects are seen in 37.5% in class I, 25% in class II division I, 0% in class II division II, and 37.5% in class III. Linguodental speech defects are seen in class III malocclusion subjects only. Lingua-alveolar sounds are seen in 27.8% of class I, 29.6% of class II division I, 1.9% of class II division II, and 40.7% of class III. Bilabial speech defects are only seen in class II division I subjects. According to the results, only lingua-alveolar speech defects are statistically significant, and more severe speech defects were observed in class III malocclusion. Conclusion Speech plays an important role in affecting the quality of life of people. Different types of malocclusion traits are associated with different types of speech defects.

Chemoradiation to the submental muscles alters hyoid movement during swallowing in a rat model

Hyolaryngeal dysfunction is a commonly reported swallowing problem after chemoradiation treatment for head and neck cancer. The displacement of the hyolaryngeal complex during swallowing protects the airway and assists in opening the upper esophageal sphincter. Activation of the submental muscles, specifically the mylohyoid and geniohyoid muscles, is thought to facilitate movement of the hyoid. The purpose of this study was to determine if targeted radiation to the submental muscles given concurrently with chemotherapy alters hyolaryngeal displacement 1 mo after treatment. We hypothesized that chemoradiation treatment would result in abnormal patterns of hyoid movement compared with controls. Furthermore, we propose that these changes are associated with alterations in bolus size and discoordination of the jaw during drinking. Eighteen rats underwent either chemoradiation, radiation, or no treatment. Radiation treatment was targeted to submental muscles using a clinical linear accelerator given in 12 fractions of 4 Gy (3 days per week). Cycles of 1 mg/kg of cisplatin were administered concurrently each week of radiation. One month posttreatment, videofluoroscopy swallow studies (VFSS) were performed in self-drinking rats using a fluoroscope customized with a high-speed camera. The hyoid, jaw, and hard palate were tracked during swallowing from VFSS. Hyoid kinematics were analyzed from the start to the end of hyoid movement, and parameters were compared with bolus size and jaw movement. Significant differences in hyoid retraction parameters were found postchemoradiation. Alterations in the trajectory of hyoid motion during swallowing were observed. The findings demonstrate early changes in hyoid motion during swallowing associated with chemoradiation treatment.NEW & NOTEWORTHY Chemoradiation treatment for head and neck cancer can cause functional impairments in swallowing, which can adversely affect quality of life. This study provides new evidence that chemoradiation targeted to the submental muscles provokes early adaptations in hyoid movement during swallowing, which correlate with changes in bolus size. We also demonstrate a method for tracking the hyoid during swallowing in a rat model of chemoradiation injury.

Surface Electromyographic Activity of the Masseter Muscle During Regular and Effortful Saliva Swallows: A Preliminary Study

Biofeedback is a critical component in motor learning of new, complex behaviors such as modifications to swallowing. Surface electromyography (sEMG) is a commonly employed biofeedback tool in swallowing management to assess muscle activity patterns, determine amplitude and duration of swallowing, and train swallowing strategies such as the effortful swallow (EFS) maneuver. The EFS can potentially change multiple physiological components of the swallowing process such as pressure generation and movement of biomechanical structures. The purposes of this study were to determine whether the masseter muscle could differentiate a normal swallow (NS) from an EFS and whether there was a relationship between perceived muscle effort used to swallow and objective measures of muscle activity. Twenty healthy young adults participated in this study. Masseter sEMG peak amplitude and duration were measured across five regular saliva swallows and five effortful saliva swallows. Additionally, participants rated their perceived swallowing effort using a visual analog scale (VAS). Two swallowing conditions, NSs and EFSs were compared with hierarchical models, and repeated measures correlation was used to determine the relationships between the VAS and sEMG peak amplitude. Participants produced swallows with greater masseter sEMG peak amplitude and duration during the EFS. Moreover, a positive correlation was identified between perceived swallowing effort and masseter sEMG peak amplitude. These findings support the potential use of the masseter muscle to differentiate NSs from EFSs and implement the VAS during therapy for tracking patients' performance, particularly in settings with limited access to sEMG.

Mechanisms of Swallowing, Speech and Voice Disorders in Parkinson's Disease: Literature Review with Our First Evidence for the Periperal Nervous System Involvement

The majority of patients with Parkinson's disease (PD) develop swallowing, speech, and voice (SSV) disorders. Importantly, swallowing difficulty or dysphagia and related aspiration are life-threatening conditions for PD patients. Although PD treatments have significant therapeutic effects on limb motor function, their effects on SSV disorders are less impressive. A large gap in our knowledge is that the mechanisms of SSV disorders in PD are poorly understood. PD was long considered to be a central nervous system disorder caused by the death of dopaminergic neurons in the basal ganglia. Aggregates of phosphorylated α-synuclein (PAS) underlie PD pathology. SSV disorders were thought to be caused by the same dopaminergic problem as those causing impaired limb movement; however, there is little evidence to support this. The pharynx, larynx, and tongue play a critical role in performing upper airway (UA) motor tasks and their dysfunction results in disordered SSV. This review aims to provide an overview on the neuromuscular organization patterns, functions of the UA structures, clinical features of SSV disorders, and gaps in knowledge regarding the pathophysiology underlying SSV disorders in PD, and evidence supporting the hypothesis that SSV disorders in PD could be associated, at least in part, with PAS damage to the peripheral nervous system controlling the UA structures. Determining the presence and distribution of PAS lesions in the pharynx, larynx, and tongue will facilitate the identification of peripheral therapeutic targets and set a foundation for the development of new therapies to treat SSV disorders in PD.

Use of suction electrodes for measurement of intrinsic tongue muscular endurance during lingual pressure generation

BACKGROUND

Lingual pressure (LP) generation is cooperatively controlled not only by the intrinsic tongue (I-ton) muscles but also by hyoid muscle activation. However, the measurement of endurance and fatigue properties of I-ton muscles is difficult due to the instability of electrodes.

OBJECTIVE

The purpose of this study was to apply suction electrodes to measure electromyograms (EMGs) of I-ton muscle and to evaluate integrated EMG amplitude (iEMG) and mean power frequency (MPF) of EMG in the I-ton and hyoid muscles performing continuous LP.

METHODS

Twenty healthy adult volunteers (10 males, 10 females, mean age 28.8 years) were instructed to perform 10-s LP generation tasks at 25%, 50%, 75% and 100% of maximum LP in randomised order with visual feedback. During each task, EMGs of the I-ton, suprahyoid (S-hyo), infrahyoid (I-hyo) and masseter (Mass) muscles were simultaneously recorded. The iEMG and MPF of EMG burst during 10-s LP tasks were compared. The recording period was divided into three substages to analyse temporal changes with the Friedman test.

RESULTS

During the 10-s task, the iEMG significantly increased as the LP strength increased (p < .001). There was no time-dependent change in the I-ton iEMG; however, the MPF of the I-ton EMG burst decreased in all tasks (p < .05). The S-hyo and I-hyo iEMGs gradually increased, especially with strong LP (p < .01).

CONCLUSION

While I-ton muscles may easily fatigue during 10-s LP generation, S-hyo and I-hyo muscles may help compensate for the weakened I-ton muscle activity by increasing their activity to maintain LP.

Biomechanical and Cortical Control of Tongue Movements During Chewing and Swallowing

Tongue function is vital for chewing and swallowing and lingual dysfunction is often associated with dysphagia. Better treatment of dysphagia depends on a better understanding of hyolingual morphology, biomechanics, and neural control in humans and animal models. Recent research has revealed significant variation among animal models in morphology of the hyoid chain and suprahyoid muscles which may be associated with variation in swallowing mechanisms. The recent deployment of XROMM (X-ray Reconstruction of Moving Morphology) to quantify 3D hyolingual kinematics has revealed new details on flexion and roll of the tongue during chewing in animal models, movements similar to those used by humans. XROMM-based studies of swallowing in macaques have falsified traditional hypotheses of mechanisms of tongue base retraction during swallowing, and literature review suggests that other animal models may employ a diversity of mechanisms of tongue base retraction. There is variation among animal models in distribution of hyolingual proprioceptors but how that might be related to lingual mechanics is unknown. In macaque monkeys, tongue kinematics-shape and movement-are strongly encoded in neural activity in orofacial primary motor cortex, giving optimism for development of brain-machine interfaces for assisting recovery of lingual function after stroke. However, more research on hyolingual biomechanics and control is needed for technologies interfacing the nervous system with the hyolingual apparatus to become a reality.

Three-Dimensional Analysis of Flap Volume Change in Total Tongue Reconstruction: Focus on Reinnervated Dynamic Tongue Reconstruction

In general, flap volume decreases over time and further in the case of a denervated muscle flap. In our institution, dynamic reconstruction, including functional muscle flaps, has been used to aid functional recovery in the past 6 years. This study aimed to determine the effect of volume change of the fat and muscular sections of reconstructed tongue flaps after motor nerve reinnervation in dynamic total tongue reconstruction using 3-dimensional measurement and analysis. A retrospective chart review was performed on 21 patients who underwent total tongue reconstruction using an anterolateral thigh free flap from 2015 to 2020. The fat and muscle volumes of the flap were measured using computed tomography data obtained before surgery (T0), 2 weeks after surgery (T1), and 6 months after surgery (T2) using a 3-dimensional rendering software. Among the 21 patients that underwent tongue reconstruction, 10 underwent dynamic reconstruction, whereas 11 underwent conventional reconstruction using a fasciocutaneous flap. T2 volume compared with T1 was 69.08% in the conventional reconstruction group, and the fat and muscle portions in the dynamic reconstruction group were 77.04% and 69.06%, respectively. No significant difference was noted in the volume change between the 2 groups. After dynamic tongue reconstruction, the muscular volume of the flap had similar volume reduction rate as the fat volume. The dynamic reconstruction was effective not only for functional muscle transfer but also for maintaining the volume of the reconstructed muscle flap.

Clinical Neurology in Practice: The Tongue (Part 1)

BACKGROUND

The tongue is an essential organ for the development of certain crucial functions, such as swallowing and language. The examination of the tongue can be very useful in neurology, as the various types of lingual alterations can lead to certain specific diagnoses, the tongue being a kind of "mirror" of some neurological function.

REVIEW SUMMARY

In this study, we reviewed the literature on anatomy, physiology, and the various aspects of the examination of the tongue.

CONCLUSIONS

Examination of the tongue should be an integral part of the clinical examination of the cranial nerves. This study aimed to demonstrate the importance of tongue motor and non-motor functions in neurological practice.

Cetacean tongue mobility and function: A comparative review

Cetaceans are atypical mammals whose tongues often depart from the typical (basal) mammalian condition in structure, mobility, and function. Their tongues are dynamic, innovative multipurpose tools that include the world's largest muscular structures. These changes reflect the evolutionary history of cetaceans' secondary adaptation to a fully aquatic environment. Cetacean tongues play no role in mastication and apparently a greatly reduced role in nursing (mainly channeling milk ingestion), two hallmarks of Mammalia. Cetacean tongues are not involved in drinking, breathing, vocalizing, and other non-feeding activities; they evidently play no or little role in taste reception. Although cetaceans do not masticate or otherwise process food, their tongues retain key roles in food ingestion, transport, securing/positioning, and swallowing, though by different means than most mammals. This is due to cetaceans' aquatic habitat, which in turn altered their anatomy (e.g., the intranarial larynx and consequent soft palate alteration). Odontocetes ingest prey via raptorial biting or tongue-generated suction. Odontocete tongues expel water and possibly uncover benthic prey via hydraulic jetting. Mysticete tongues play crucial roles driving ram, suction, or lunge ingestion for filter feeding. The uniquely flaccid rorqual tongue, not a constant volume hydrostat (as in all other mammalian tongues), invaginates into a balloon-like pouch to temporarily hold engulfed water. Mysticete tongues also create hydrodynamic flow regimes and hydraulic forces for baleen filtration, and possibly for cleaning baleen. Cetacean tongues lost or modified much of the mobility and function of generic mammal tongues, but took on noteworthy morphological changes by evolving to accomplish new tasks.

Glossectomy for the treatment of oral cavity carcinoma: Quantitative, functional and patient-reported quality of life outcomes differ by four glossectomy defects

OBJECTIVE

The goal was to characterize four clinically distinct glossectomy defects to establish significant quantitative cut points using functional metrics, the MD Anderson Dysphagia Index (MDADI) and speech intelligibility.

METHODS

Population included 101 patients treated with surgery, adjuvant radiation per NCCN guidelines, and ≥ 12 months follow-up.

RESULTS

Defect groups: subtotal hemiglossectomy (1), hemiglossectomy (2), extended hemiglossectomy (3) and oral glossectomy (4) were compared: All outcomes supported a four defect model. Intergroup comparison of outcomes with subtotal hemiglossectomy as reference (p value): Tongue Protrusion <0.001,<0.001,<0.001; Elevation <0.001,<0.001,<0.001; Open Mouth Premaxillary Contact Elevation <0.001,<0.001,<0.001; Obliteration 0.6,<0.001,<0.001; Normalcy of Diet, <0.3,<0.001,<0.001; Nutritional Mode, <0.9,<0.8,<0.001; Range of Liquids, <0.4,<0.016,<0.02; Range of Solids, <0.5,<0.004,<0.001; Eating in Public, <0.2,<0.002,<0.03; Understandability of Speech, <0.9,<0.001,<0.001; Speaking in Public, <0.4,<0.03,<0.001; MDADI, <0.4,<0.005,<0.01; Single Word Intelligibility, <0.4,<0.1,<0.001; Sentence Intelligibility, <0.5,<0.08,<0.001; Words Per Minute Intelligibility, <0.6,<0.04,<0.001; Sentence Efficiency Ratio, <0.4,<0.03,<0.002. Proportion of patients by 4 defect groups who underwent: tissue transplantation, 51%,93.9%,100%,100%.Radiation,24%,67%,88%,80%.Between hemiglossectomy and extended hemiglossectomy, the defect extends into the contralateral floor of the mouth and/or the anterior tonsillar pillar; resection of these subunits limits tongue mobility with an impact on functional outcome and MDADI. Between extended hemiglossectomy and oral glossectomy, the defect extends to include the tip of the tongue and appears to impact functional outcome and MDADI.

CONCLUSIONS

Subtotal hemiglossectomy, hemiglossectomy, extended glossectomy and oral glossectomy are associated with quantitative (elevation, protrusion, open mouth premaxillary contact and obliteration), qualitative (speech and swallowing) and MDADI differences, suggesting that these 4 ordinal defect groups are distinct.

Robust cortical encoding of 3D tongue shape during feeding in macaques

Dexterous tongue deformation underlies eating, drinking, and speaking. The orofacial sensorimotor cortex has been implicated in the control of coordinated tongue kinematics, but little is known about how the brain encodes-and ultimately drives-the tongue's 3D, soft-body deformation. Here we combine a biplanar x-ray video technology, multi-electrode cortical recordings, and machine-learning-based decoding to explore the cortical representation of lingual deformation. We trained long short-term memory (LSTM) neural networks to decode various aspects of intraoral tongue deformation from cortical activity during feeding in male Rhesus monkeys. We show that both lingual movements and complex lingual shapes across a range of feeding behaviors could be decoded with high accuracy, and that the distribution of deformation-related information across cortical regions was consistent with previous studies of the arm and hand.

Analysis of Tongue Muscle Strain During Speech From Multimodal Magnetic Resonance Imaging

PURPOSE

Muscle groups within the tongue in healthy and diseased populations show different behaviors during speech. Visualizing and quantifying strain patterns of these muscle groups during tongue motion can provide insights into tongue motor control and adaptive behaviors of a patient.

METHOD

We present a pipeline to estimate the strain along the muscle fiber directions in the deforming tongue during speech production. A deep convolutional network estimates the crossing muscle fiber directions in the tongue using diffusion-weighted magnetic resonance imaging (MRI) data acquired at rest. A phase-based registration algorithm is used to estimate motion of the tongue muscles from tagged MRI acquired during speech. After transforming both muscle fiber directions and motion fields into a common atlas space, strain tensors are computed and projected onto the muscle fiber directions, forming so-called strains in the line of actions (SLAs) throughout the tongue. SLAs are then averaged over individual muscles that have been manually labeled in the atlas space using high-resolution T2-weighted MRI. Data were acquired, and this pipeline was run on a cohort of eight healthy controls and two glossectomy patients.

RESULTS

The crossing muscle fibers reconstructed by the deep network show orthogonal patterns. The strain analysis results demonstrate consistency of muscle behaviors among some healthy controls during speech production. The patients show irregular muscle patterns, and their tongue muscles tend to show more extension than the healthy controls.

CONCLUSIONS

The study showed visual evidence of correlation between two muscle groups during speech production. Patients tend to have different strain patterns compared to the controls. Analysis of variations in muscle strains can potentially help develop treatment strategies in oral diseases.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.21957011.

Lip service: Histological phenotypes correlate with diet and feeding ecology in herbivorous pacus

Complex prey processing requires the repositioning of food between the teeth, as modulated by a soft tissue appendage like a tongue or lips. In this study, we trace the evolution of lips and ligaments, which are used during prey capture and prey processing in an herbivorous group of fishes. Pacus (Serrasalmidae) are Neotropical freshwater fishes that feed on leaves, fruits, and seeds. These prey are hard or tough, require high forces to fracture, contain abrasive or caustic elements, or deform considerably before failure. Pacus are gape-limited and do not have the pharyngeal jaws many bony fishes use to dismantle and/or transport prey. Despite their gape limitation, pacus feed on prey larger than their mouths, relying on robust teeth and a hypertrophied lower lip for manipulation and breakdown of food. We used histology to compare the lip morphology across 14 species of pacus and piranhas to better understand this soft tissue. We found that frugivorous pacus have larger, more complex lips which are innervated and folded at their surface, while grazing species have callused, mucus-covered lips. Unlike mammalian lips or tongues, pacu lips lack any intrinsic skeletal or smooth muscle. This implies that pacu lips lack dexterity; however, we found a novel connection to the primordial ligament which suggests that the lips are actuated by the jaw adductors. We propose that pacus combine hydraulic repositioning of prey inside the buccal cavity with direct oral manipulation, the latter using a combination of a morphologically heterodont dentition and compliant lips for reorienting food.

In vitro oral simulation based on soft contact: The importance of viscoelastic response of the upper jaw substitutes

Real oral processing is the squeezing and shearing between two soft surfaces. The importance of soft palate surface cannot be ignored while focusing on tongue substitutes. Thus the effects of viscoelasticity, roughness of upper jaw substitutes, and fluid rheological properties on lubrication properties were explored by in vitro oral tribology experiments. Different palate substitutes significantly changed the friction curves of pure water, milk, and yogurt. The boundary friction coefficients of pure water and milk are higher under softer or smooth palate substitutes due to stronger viscoelastic responses of friction pairs. Their boundary friction coefficients are lowest at rigid upper jaw substitutes owing to smaller contact angles and deformation. However, the boundary friction coefficient of yogurt is lower owing to its high viscosity, low loss factor, and large particle size under soft friction pairs. In addition, it is highest at rigid palate friction pair because a smaller contact area reduces the entrainment of yogurt, resulting in poor lubricating performance.

Insights into the Multiscale Lubrication Mechanism of Edible Phase Change Materials

Investigation of a lubrication behavior of phase change materials (PCM) can be challenging in applications involving relative motion, e.g., sport (ice skating), food (chocolates), energy (thermal storage), apparel (textiles with PCM), etc. In oral tribology, a phase change often occurs in a sequence of dynamic interactions between the ingested PCM and oral surfaces from a licking stage to a saliva-mixed stage at contact scales spanning micro- (cellular), meso- (papillae), and macroscales. Often the lubrication performance and correlations across length scales and different stages remain poorly understood due to the lack of testing setups mimicking real human tissues. Herein, we bring new insights into lubrication mechanisms of PCM using dark chocolate as an exemplar at a single-papilla (meso)-scale and a full-tongue (macro) scale covering the solid, molten, and saliva-mixed states, uniting highly sophisticated biomimetic oral surfaces with in situ tribomicroscopy for the first time. Unprecedented results from this study supported by transcending lubrication theories reveal how the tribological mechanism in licking shifted from solid fat-dominated lubrication (saliva-poor regime) to aqueous lubrication (saliva-dominant regime), the latter resulted in increasing the coefficient of friction by at least threefold. At the mesoscale, the governing mechanisms were bridging of cocoa butter in between confined cocoa particles and fat coalescence of emulsion droplets for the molten and saliva-mixed states, respectively. At the macroscale, a distinctive hydrodynamic viscous film formed at the interface governing the speed-dependent lubrication behavior indicates the striking importance of multiscale analyses. New tribological insights across different stages and scales of phase transition from this study will inspire rational design of the next generation of PCM and solid particle-containing materials.

Assessment of Dysphagia after Hemiglossectomy and Radiotherapy: A Prospective Study

Background Malignancy of the tongue is a common condition affecting patients and their day-to-day activities. The tongue plays an important role in deglutition. The combination treatment modality involving surgical resection with or without reconstruction and radiation is the most commonly used modality for such lesions. This in turn has a profound impact on the quality of life of the patients owing to the nature of the treatment.

Aim of the study This study aimed to assess swallowing in patients with carcinoma tongue following hemiglossectomy and radiotherapy (RT).

Methodology A prospective study carried out in 20 patients who underwent hemiglossectomy with primary closure for carcinoma of the tongue followed by RT. All patients were evaluated for swallowing using the Dysphagia Handicap Index before surgery; after surgery on the 10th and 30th days; during RT after 15 fractions of radiation; and after 1, 2, and 3 months postcompletion of RT.

Results The Dysphagia Handicap Index has significantly increased from the preoperative value following both surgery and RT on all follow-up visits (p < 0.001). The most severe self-reported dysphagia was noted during and after RT(p < 0.001).

Conclusion This study shows that hemiglossectomy followed by primary closure with adjuvant RT has a severe negative impact on swallowing, thereby affecting the quality of life.

Assessment of Speech in Patients Undergoing Hemiglossectomy with Primary Closure and Radiotherapy - A Prospective Study

Introduction

The oral cavity plays a pivotal role in the generation of speech. The treatment of oral squamous cell carcinoma of the tongue requires an aggressive approach, combining resective surgery along with radiation therapy, with long-lasting effects on the patient's ability to speak. This study was designed to assess speech in subjects with carcinoma of the tongue following hemiglossectomy with primary closure and radiotherapy.

Methods

A prospective study was carried out in 20 subjects who underwent hemiglossectomy with primary closure for carcinoma of the tongue followed by radiotherapy. All subjects were evaluated for speech using 'Kannada Diagnostic Photo Articulation Test' before surgery, after surgery (on the 10th and 30th day), during radiation therapy after 15 fractions of radiation and after 1, 2 and 3 months following completion of radiotherapy. Statistical analysis was performed using SPSS software (v. 17.0). Significance levels were determined using ANOVA followed by Bonferroni correction.

Results

Intelligibility of speech was noted to be affected most at the one month follow-up visit after completion of radiotherapy (P < 0.001). The Kannada Diagnostic Photo Articulation Test proves to be a useful tool in assessing changes in speech, with results that can be replicated in further studies.

Discussion

The incidence of articulatory errors is increased following surgery and radiotherapy. Over time, the number of errors reduce and approach the baseline, indicating that although speech is indeed hampered by the treatment, with adequate speech therapy one can regain their preoperative articulation.

Beyond language: The unspoken sensory-motor representation of the tongue in non-primates, non-human and human primates

The English idiom "on the tip of my tongue" commonly acknowledges that something is known, but it cannot be immediately brought to mind. This phrase accurately describes sensorimotor functions of the tongue, which are fundamental for many tongue-related behaviors (e.g., speech), but often neglected by scientific research. Here, we review a wide range of studies conducted on non-primates, non-human and human primates with the aim of providing a comprehensive description of the cortical representation of the tongue's somatosensory inputs and motor outputs across different phylogenetic domains. First, we summarize how the properties of passive non-noxious mechanical stimuli are encoded in the putative somatosensory tongue area, which has a conserved location in the ventral portion of the somatosensory cortex across mammals. Second, we review how complex self-generated actions involving the tongue are represented in more anterior regions of the putative somato-motor tongue area. Finally, we describe multisensory response properties of the primate and non-primate tongue area by also defining how the cytoarchitecture of this area is affected by experience and deafferentation.

Loss of oral sensation impairs feeding performance and consistency of tongue-jaw coordination

Background

Individuals with impaired oral sensation report difficulty chewing, but little is known about the underlying changes to tongue and jaw kinematics. Methodological challenges impede the measurement of 3D tongue movement and its relationship to the gape cycle.

Objective

The aim of this study was to quantify the impact of loss of oral somatosensation on feeding performance, 3D tongue kinematics and tongue‐jaw coordination.

Methodology

XROMM (X‐ray Reconstruction of Moving Morphology) was used to quantify 3D tongue and jaw kinematics during feeding in three rhesus macaques (Macaca mulatta) before and after an oral tactile nerve block. Feeding performance was measured using feeding sequence duration, number of manipulation cycles and swallow frequency. Coordination was measured using event‐ and correlation‐based metrics of jaw pitch, anterior tongue length, width and roll.

Results

In the absence of tactile sensation to the tongue and other oral structures, feeding performance decreased, and the fast open phase of the gape cycle became significantly longer, relative to the other phases (p < .05). The tongue made similar shapes in both the control and nerve block conditions, but the pattern of tongue‐jaw coordination became significantly more variable after the block (p < .05).

Conclusion

Disruption of oral somatosensation impacts feeding performance by introducing variability into the typically tight pattern of tongue‐jaw coordination.

The Effect of Corn Dextrin on the Rheological, Tribological, and Aroma Release Properties of a Reduced-Fat Model of Processed Cheese Spread

Low-calorie and low-fat foods have been introduced to the market to fight the increasing incidence of overweightness and obesity. New approaches and high-quality fat replacers may overcome the poor organoleptic properties of such products. A model of processed cheese spread (PCS) was produced as a full-fat version and with three levels of fat reduction (30%, 50%, and 70%). Fat was replaced by water or by corn dextrin (CD), a dietary fiber. Additionally, in the 50% reduced-fat spreads, fat was replaced by various ratios of CD and lactose (100:0, 75:25, 50:50, 25:75, and 0:100). The effect of each formulation was determined by measuring the textural (firmness, stickiness, and spreadability), rheological (flow behavior and oscillating rheology), tribological, and microstructural (cryo-SEM) properties of the samples, as well as the dynamic aroma release of six aroma compounds typically found in cheese. Winter’s critical gel theory was a good approach to characterizing PCS with less instrumental effort and costs: the gel strength and interaction factors correlated very well with the spreadability and lubrication properties of the spreads. CD and fat exhibited similar interaction capacities with the aroma compounds, resulting in a similar release pattern. Overall, the properties of the sample with 50% fat replaced by CD were most similar to those of the full-fat sample. Thus, CD is a promising fat replacer in PCS and, most likely, in other dairy-based emulsions.

Palatal Electrotactile Display Outperforms Visual Display in Tongue Motor learning

Incomplete tongue motor control is a common yet challenging issue among individuals with neurotraumas and neurological disorders. In development of the training protocols, multiple sensory modalities including visual, auditory, and tactile feedback have been employed. However, the effectiveness of each sensory modality in tongue motor learning is still in question. The object of this study was to test the effectiveness of visual and electrotactile assistance on tongue motor learning, respectively. Eight healthy subjects performed the tongue pointing task, in which they were visually instructed to touch the target on the palate by their tongue tip as accurately as possible. Each subject wore a custom-made dental retainer with 12 electrodes distributed over the palatal area. For visual training, 3×4 LED array on the computer screen, corresponding to the electrode layout, was turned on with different colors according to the tongue contact. For electrotactile training, electrical stimulation was applied to the tongue with frequencies depending on the distance between the tongue contact and the target, along with a small protrusion on the retainer as an indicator of the target. One baseline session, one training session, and three post-training sessions were conducted over four-day duration. Experimental result showed that the error was decreased after both visual and electrotactile trainings, from 3.56±0.11 (Mean±STE) to 1.27±0.16, and from 3.97±0.11 to 0.53±0.19, respectively. The result also showed that electrotactile training leads to stronger retention than visual training, as the improvement was retained as 62.68±1.81% after electrotactile training and 36.59±2.24% after visual training, at 3-day post training.

Impaired tongue motor control after temporomandibular disorder: A proof-of-concept case-control study of tongue print

BACKGROUND

Temporomandibular disorder (TMD) perturbs the tongue motor control and consequently impairs oral function, but strength training reduces this impairment. However, tongue motor control is widely reduced to a matter of strength.

OBJECTIVES

To investigate the accuracy of the tongue placement as a measure of tongue motor control in patients with TMD compared with age- and sex-matched healthy participants.

MATERIAL AND METHODS

This proof-of-concept case-control study was prospective, observational, and part of the TMIQ study (NCT04102306). After pointing against a wood stick while maintaining the tongue as sharp as possible, the examinator drew the contour of the tongue print on the wood stick, which was then scanned for image analyses to compute the area for each participant using ImageJ.

RESULTS

A total of 94 participants were included, all patients with TMD (n = 47) diagnosed with myalgia, 61% with intra-articular joint disorder accordingly to the DC/TMD. The median (IQR) tongue print area was 117 (111) mm² for the TMD group and 93.5 (76.2) mm² for the control group (V = 352, p = .04) and the median [95% confidence interval] difference was 25.4 [1.3; 51.0] mm². Overlapping of the 95% confidence intervals of the area evidenced no significant difference between the categories of the DC/TMD. The corrected each area-total correlation (r = .24) suggests a reasonably homogenous thus valid measure.

CONCLUSION

The results suggest that TMD impairs the motor control of the tongue. Therefore, the sharpest tongue pointing test may constitute a simple and accessible clinical tool to assess the accuracy of tongue placement in TMD patients. The study was registered on ClinicalTrial.gov with identification number NCT04102306.

Impact of Frailty on Dietary Habits among Community-Dwelling Older Persons during the COVID-19 Pandemic in Japan

Background

The coronavirus disease (COVID-19) pandemic has resulted in reduced physical activity and social interaction. These restrictions may have affected the food intake habits of frail older people more than non-frail older people.

Objectives

To investigate the association between frailty and change in dietary habit during the pandemic.

Design

Cross-sectional mail survey

Setting

Community-based

Participants

The study questionnaire was mailed to 4,436 older residents of Higashiura, Aich Japan, who were aged ≥75 years and who did not need care as of April 1, 2020. Of these, 2,738 participants provided complete answers to the questionnaires (75–96 years old, 49.3% males).

Measurements

The participants’ frailty status and changes in food consumption during social isolation were assessed. Frailty status was assessed using the five-item frailty screening index (i.e., weight loss, low physical function, low physical activity, cognition, and exhaustion). Any participant who reported an increase or a decrease in ≥1 of the 12 food categories was defined as having change in dietary habit. Using multivariate logistic regression analysis, the odds ratios (ORs) and 95% confidence intervals (CIs) of frailty for changes in diet were estimated by adjusting for age, sex, BMI, and living alone. In each of the 12 food categories, the proportion of participants with increased and decreased food intake was compared between the groups.

Results

Among the participants, 470 (17.2%) were frail, and 1,097 (40.1%) experienced a change in dietary habit under social restriction. The adjusted OR (95% CI) of the frail group for a change in dietary habit was 2.01 (1.63–2.47, p<0.001). Participants with decreased consumption of meat, fish, seaweed and mushroom, and fruits and those with increased consumption of eggs, bread, and noodles tended to be frail.

Conclusion

The nutritional intervention for frail older people should be strengthened during the pandemic.

Probing the multimodal fungiform papilla: complex peripheral nerve endings of chorda tympani taste and mechanosensitive fibers before and after Hedgehog pathway inhibition

The fungiform papilla (FP) is a gustatory and somatosensory structure incorporating chorda tympani (CT) nerve fibers that innervate taste buds (TB) and also contain somatosensory endings for touch and temperature. Hedgehog (HH) pathway inhibition eliminates TB, but CT innervation remains in the FP. Importantly, after HH inhibition, CT neurophysiological responses to taste stimuli are eliminated, but tactile responses remain. To examine CT fibers that respond to tactile stimuli in the absence of TB, we used Phox2b-Cre; Rosa26^{LSL−TdTomato} reporter mice to selectively label CT fibers with TdTomato. Normally CT fibers project in a compact bundle directly into TB, but after HH pathway inhibition, CT fibers reorganize and expand just under the FP epithelium where TB were. This widened expanse of CT fibers coexpresses Synapsin-1, β-tubulin, S100, and neurofilaments. Further, GAP43 expression in these fibers suggests they are actively remodeling. Interestingly, CT fibers have complex terminals within the apical FP epithelium and in perigemmal locations in the FP apex. These extragemmal fibers remain after HH pathway inhibition. To identify tactile end organs in FP, we used a K20 antibody to label Merkel cells. In control mice, K20 was expressed in TB cells and at the base of epithelial ridges outside of FP. After HH pathway inhibition, K20 + cells remained in epithelial ridges but were eliminated in the apical FP without TB. These data suggest that the complex, extragemmal nerve endings within and disbursed under the apical FP are the mechanosensitive nerve endings of the CT that remain after HH pathway inhibition.

Ultrasonic Imaging Investigation of Tongue Movement Patterns of Cleft-Related Lateralized and Palatalized Misarticulation

OBJECTIVES

To explore the tongue movement patterns on Mandarin speaking children with repaired cleft palate with lateralized and palatalized misarticulation (LPM) using ultrasound imaging technique.

METHODS

A group of 20 subjects who were diagnosed with speech sound disorder after cleft palate repairment, and another group of 18 children with LPM were recruited. A group of 20 typical children were recruited as the control group. The ultrasonography was used to collect the articulation pattern of the 8 single vowels that are /a/, /o/, /[Latin Small Letter Reversed e]/, /i/, /u/, /y/, /ɨ/, /u/ in Mandarin Chinese. Various ultrasonic tongue parameters were analyzed from both sagittal and coronal planes.

RESULTS

Compared with the control group, coronal height of peak point, coronal tongue dorsum constraint index, sagittal peak point offset distance, sagittal distance between tongue tip and peak point, and sagittal tongue dorsum constraint index of /[Latin Small Letter Reversed e]/,/i/, /y/ and /ɨ/ were significantly smaller in the cleft-related lateralized and palatalized group (CLP) and noncleft-related lateralized and palatalized group (NLP) (P < 0.05). Compared with the noncleft-related lateralized and palatalized group and control group, sagittal peak point offset distance of the vowels /[Latin Small Letter Reversed e]/ and /i/ was significant smaller in the cleft-related lateralized and palatalized group group (P < 0.05).

CONCLUSIONS

The ultrasound images on the children with cleft palate showed a midline elevation of the tongue and a significant apical constriction. The children with LPM showed a midline elevation at the coronal plane and anterior movement of the tongue high point at the sagittal plane. The apical vowels were more informative and accurate in indicating the features of LPM than other vowels.

Progressive Protrusive Tongue Exercise Does Not Alter Aging Effects in Retrusive Tongue Muscles

Purpose: Exercise-based treatment approaches for dysphagia may improve swallow function in part by inducing adaptive changes to muscles involved in swallowing and deglutition. We have previously shown that both aging and progressive resistance tongue exercise, in a rat model, can induce biological changes in the genioglossus (GG); a muscle that elevates and protrudes the tongue. However, the impacts of progressive resistance tongue exercise on the retrusive muscles (styloglossus, SG; hyoglossus, HG) of the tongue are unknown. The purpose of this study was to examine the impact of a progressive resistance tongue exercise regimen on the retrusive tongue musculature in the context of aging. Given that aging alters retrusive tongue muscles to more slowly contracting fiber types, we hypothesized that these biological changes may be mitigated by tongue exercise.

Methods: Hyoglossus (HG) and styloglossus (SG) muscles of male Fischer 344/Brown Norway rats were assayed in age groups of young (9 months old, n = 24), middle-aged (24 months old, n = 23), and old (32 months old, n = 26), after receiving an 8-week period of either progressive resistance protrusive tongue exercise, or sham exercise conditions. Following exercise, HG and SG tongue muscle contractile properties were assessed in vivo. HG and SG muscles were then isolated and assayed to determine myosin heavy chain isoform (MyHC) composition.

Results: Both retrusive tongue muscle contractile properties and MyHC profiles of the HG and SG muscles were significantly impacted by age, but were not significantly impacted by tongue exercise. Old rats had significantly longer retrusive tongue contraction times and longer decay times than young rats. Additionally, HG and SG muscles showed significant MyHC profile changes with age, in that old groups had slower MyHC profiles as compared to young groups. However, the exercise condition did not induce significant effects in any of the biological outcome measures.

Conclusion: In a rat model of protrusive tongue exercise, aging induced significant changes in retrusive tongue muscles, and these age-induced changes were unaffected by the tongue exercise regimen. Collectively, results are compatible with the interpretation that protrusive tongue exercise does not induce changes to retrusive tongue muscle function.

Tongue measurements and pharyngeal residue in amyotrophic lateral sclerosis

Aim: We aimed to analyze the relationship between tongue measurements and vallecular residue in patients with amyotrophic lateral sclerosis (ALS). Materials & methods: Twenty-one patients with ALS were assessed for posterior maximum tongue isometric pressure (PMTIP) and posterior tongue isometric endurance (PTIE) by the Iowa Oral Performance Instrument; vallecular residue after 10 ml of moderately thickened consistency by Fiberoptic Endoscopic Evaluation of Swallowing; and tongue thickness (TT) by ultrasonography. Results: PMTIP, PTIE and TT were decreased compared with the reference values for healthy individuals and were not different between patients with and without vallecular residue. Conclusion: In ALS, PMTIP, PTIE and TT are not good predictors of vallecular residue in the tested volume and food consistency.

Exploring directional and fluctuating asymmetry in the human palate during growth

Objectives

Palate morphology is constantly changing throughout an individual's lifespan, yet its asymmetry during growth is still little understood. In this research, we focus on the study of palate morphology by using 3D geometric morphometric approaches to observe changes at different stages of life, and to quantify the impact of directional and fluctuating asymmetry on different areas at different growth stages.

Materials and Methods

The sample consists of 183 individuals (1–72 years) from two identified human skeletal collections of 19th and early 20th Century Italian contexts. A 3D‐template of 41 (semi)landmarks was applied on digital palate models to observe morphological variation during growth.

Results

Asymmetrical components of the morphological structure appears multidirectional on the entire palate surface in individuals <2 years old and become oriented (opposite bilateral direction) between 2 and 6 years of age. Specifically, directional asymmetry differentially impacts palate morphology at different stages of growth. Both the anterior and posterior palate are affected by mild alterations in the first year of life, while between 2 and 6 years asymmetry is segregated in the anterior area, and moderate asymmetry affects the entire palatal surface up to 12 years of age. Our results show that stability of the masticatory system seems to be reached around 13–35 years first by females and then males. From 36 years on both sexes show similar asymmetry on the anterior area. Regarding fluctuating asymmetry, inter‐individual variability is mostly visible up to 12 years of age, after which only directional trends can be clearly observed at a group level.

Discussion

Morphological structure appears instable during the first year of life and acquires an opposite asymmetric bilateral direction between 2 and 6 years of age. This condition has been also documented in adults; when paired with vertical alteration, anterior/posterior asymmetry seems to characterize palate morphology, which is probably due to mechanical factors during the lifespan. Fluctuating asymmetry is predominant in the first period of life due to a plausible relationship with the strength of morphological instability of the masticatory system. Directional asymmetry, on the other hand, shows that the patterning of group‐level morphological change might be explained as a functional response to differential inputs (physiological forces, nutritive and non‐nutritive habits, para‐masticatory activity as well as the development of speech) in different growth stages. This research has implications with respect to medical and evolutionary fields. In medicine, palate morphology should be considered when planning orthodontic and surgical procedures as it could affect the outcome. As far as an evolutionary perspective is concerned the dominance of directional asymmetries in the masticatory system could provide information on dietary and cultural habits as well as pathological conditions in our ancestors.

Developmental Functional Modules in Infant Vocalizations

Purpose Developmental functional modules (DFMs) are biological modules that are defined by their structural (morphological), functional, or developmental elements, and, in some cases, all three of these. This review article considers the hypothesis that vocal development in the first year of life can be understood in large part with respect to DFMs that characterize the speech production system. Method Literature is reviewed on relevant embryology, orofacial reflexes, craniofacial muscle properties, stages of vocal development, and related topics to identity candidates for DFMs. Results The following DFMs are identified and described: laryngeal, pharyngo-laryngeal, mandibular, velopharyngeal, labial complex, and lingual complex. These DFMs and their submodules, considered along with phenomena such as rhythmic movements, account for several well-documented features of vocal development in the first year of life. The proposed DFMs, rooted in embryologic, histologic, and kinematic properties, serve as low-dimensional control variables for the developing vocal tract. Each DFM is semi-autonomous but interacts with other DFMs to produce patterns of vocal behavior. Discussion Considered in relation to contemporary profiles and models of vocal development in the first year of life, DFMs have interpretive and explanatory value. DFMs complement other approaches in the study of infant vocalizations and are grounded in biology.

Data mining of an acoustic biomarker in tongue cancers and its clinical validation

The promise of speech disorders as biomarkers in clinical examination has been identified in a broad spectrum of neurodegenerative diseases. However, to the best of our knowledge, a validated acoustic marker with established discriminative and evaluative properties has not yet been developed for oral tongue cancers. Here we cross-sectionally collected a screening dataset that included acoustic parameters extracted from 3 sustained vowels /ɑ/, /i/, /u/ and binary perceptual outcomes from 12 consonant-vowel syllables. We used a support vector machine with linear kernel function within this dataset to identify the formant centralization ratio (FCR) as a dominant predictor of different perceptual outcomes across gender and syllable. The Acoustic analysis, Perceptual evaluation and Quality of Life assessment (APeQoL) was used to validate the FCR in 33 patients with primary resectable oral tongue cancers. Measurements were taken before (pre-op) and four to six weeks after (post-op) surgery. The speech handicap index (SHI), a speech-specific questionnaire, was also administrated at these time points. Pre-op correlation analysis within the APeQoL revealed overall consistency and a strong correlation between FCR and SHI scores. FCRs also increased significantly with increasing T classification pre-operatively, especially for women. Longitudinally, the main effects of T classification, the extent of resection, and their interaction effects with time (pre-op vs. post-op) on FCRs were all significant. For pre-operative FCR, after merging the two datasets, a cut-off value of 0.970 produced an AUC of 0.861 (95% confidence interval: 0.785-0.938) for T_3-4 patients. In sum, this study determined that FCR is an acoustic marker with the potential to detect disease and related speech function in oral tongue cancers. These are preliminary findings that need to be replicated in longitudinal studies and/or larger cohorts.

Jaw kinematics and tongue protraction-retraction during chewing and drinking in the pig

Mastication and drinking are rhythmic and cyclic oral behaviors that require interactions between the tongue, jaw and a food or liquid bolus, respectively. During mastication, the tongue transports and positions the bolus for breakdown between the teeth. During drinking, the tongue aids in ingestion and then transports the bolus to the oropharynx. The objective of this study was to compare jaw and tongue kinematics during chewing and drinking in pigs. We hypothesized there would be differences in jaw gape cycle dynamics and tongue protraction-retraction between behaviors. Mastication cycles had an extended slow-close phase, reflecting tooth-food-tooth contact, whereas drinking cycles had an extended slow-open phase, corresponding to tongue protrusion into the liquid. Compared with chewing, drinking jaw movements were of lower magnitude for all degrees of freedom examined (jaw protraction, yaw and pitch), and were bilaterally symmetrical with virtually no yaw. The magnitude of tongue protraction-retraction (Txt), relative to a mandibular coordinate system, was greater during mastication than during drinking, but there were minimal differences in the timing of maximum and minimum Txt relative to the jaw gape cycle between behaviors. However, during drinking, the tongue tip is often located outside the oral cavity for the entire cycle, leading to differences between behaviors in the timing of anterior marker maximum Txt. This demonstrates that there is variation in tongue-jaw coordination between behaviors. These results show that jaw and tongue movements vary significantly between mastication and drinking, which hints at differences in the central control of these behaviors.

The Fungiform Papilla Is a Complex, Multimodal, Oral Sensory Organ

When solid or liquid stimuli contact the tongue tip during eating, the sensations of taste, touch and temperature are immediately evoked, and tongue function relies on these simultaneous multimodal responses. We focus on the fungiform papilla of the anterior tongue as a complex organ for taste, tactile and thermal modalities, all via chorda tympani nerve innervation from the geniculate ganglion. Rather than a review, our aim is to revise the classic archetype of the fungiform as predominantly a taste bud residence only and instead emphasize an amended concept of the papilla as a multimodal organ. Neurophysiological maps of fungiform papillae in functional receptive fields demonstrate responses to chemical, stroking and cold lingual stimuli. Roles are predicted for elaborate extragemmal nerve endings in tactile and temperature sensations, and potential functions for keratinocytes in noncanonical sensory signaling. The fungiform papilla is presented as a polymodal lingual organ, not solely a gustatory papilla.

Development and Validation of a Probe Word List to Assess Speech Motor Skills in Children

Purpose The aim of the study was to develop and validate a probe word list and scoring system to assess speech motor skills in preschool and school-age children with motor speech disorders. Method This article describes the development of a probe word list and scoring system using a modified word complexity measure and principles based on the hierarchical development of speech motor control known as the Motor Speech Hierarchy (MSH). The probe word list development accounted for factors related to word (i.e., motoric) complexity, linguistic variables, and content familiarity. The probe word list and scoring system was administered to 48 preschool and school-age children with moderate-to-severe speech motor delay at clinical centers in Ontario, Canada, and then evaluated for reliability and validity. Results One-way analyses of variance revealed that the motor complexity of the probe words increased significantly for each MSH stage, while no significant differences in the linguistic complexity were found for neighborhood density, mean biphone frequency, or log word frequency. The probe word list and scoring system yielded high reliability on measures of internal consistency and intrarater reliability. Interrater reliability indicated moderate agreement across the MSH stages, with the exception of MSH Stage V, which yielded substantial agreement. The probe word list and scoring system demonstrated high content, construct (unidimensionality, convergent validity, and discriminant validity), and criterion-related (concurrent and predictive) validity. Conclusions The probe word list and scoring system described in the current study provide a standardized method that speech-language pathologists can use in the assessment of speech motor control. It can support clinicians in identifying speech motor difficulties in preschool and school-age children, set appropriate goals, and potentially measure changes in these goals across time and/or after intervention.

Quantitative imaging of tongue kinematics during infant feeding and adult swallowing reveals highly conserved patterns

Tongue motility is an essential physiological component of human feeding from infancy through adulthood. At present, it is a challenge to distinguish among the many pathologies of swallowing due to the absence of quantitative tools. We objectively quantified tongue kinematics from ultrasound imaging during infant and adult feeding. The functional advantage of this method is presented in several subjects with swallowing difficulties. We demonstrated for the first time the differences in tongue kinematics during breast- and bottle-feeding, showing the arrhythmic sucking pattern during bottle-feeding as compared with breastfeeding in the same infant with torticollis. The method clearly displayed the improvement of tongue motility after frenotomy in infants with either tongue-tie or restrictive labial frenulum. The analysis also revealed the absence of posterior tongue peristalsis required for safe swallowing in an infant with dysphagia. We also analyzed for the first time the tongue kinematics in an adult during water bolus swallowing demonstrating tongue peristaltic-like movements in both anterior and posterior segments. First, the anterior segment undulates to close off the oral cavity and the posterior segment held the bolus, and then, the posterior tongue propelled the bolus to the pharynx. The present methodology of quantitative imaging revealed highly conserved patterns of tongue kinematics that can differentiate between swallowing pathologies and evaluate treatment interventions. The method is novel and objective and has the potential to advance knowledge about the normal swallowing and management of feeding disorders.

Investigation of Embodied Language Processing on Command-Swallow Performance in Healthy Participants

Purpose During videofluoroscopic examination of swallowing, patients commonly are instructed to hold a bolus in their mouth until they hear a verbal instruction to swallow, which usually consists of the word swallow and is commonly referred to as the command swallow condition. The language-induced motor facilitation theory suggests that linguistic processes associated with the verbal command to swallow should facilitate the voluntary component of swallowing. As such, the purpose of the study was to examine the linguistic influences of the verbal command on swallowing. Method Twenty healthy young adult participants held a 5-ml liquid bolus in their mouth and swallowed the bolus after hearing one of five acoustic stimuli presented randomly: congruent action word (swallow), incongruent action word (cough), congruent pseudoword (spallow), incongruent pseudoword (pough), and nonverbal stimulus (1000-Hz pure tone). Suprahyoid muscle activity during swallowing was measured via surface electromyography (sEMG). Results The onset and peak sEMG latencies following the congruent action word swallow were shorter than latencies following the pure tone and pseudowords but were not different from the incongruent action word. The lack of difference between swallow and cough did not negate the positive impact of real words on timing. In contrast to expectations, sEMG activity duration and rise time were longer following the word swallow than the pure tone and pseudowords but were not different from cough. No differences were observed for peak suprahyoid muscle activity amplitude and fall times. Conclusions Language facilitation was observed in swallowing. The clinical utility of the information obtained in the study may depend on the purposes for using the command swallow and the type of patient being assessed. However, linguistic processing under the command swallow condition may alter swallow behaviors and suggests that linguistic inducement could be useful as a compensatory technique for patients with difficulty initiating oropharyngeal swallows.

Stabilization of directly acidified protein drinks by single and mixed hydrocolloids-combining particle size, rheology, tribology, and sensory data

BACKGROUND

High methoxyl pectin and carboxymethylcellulose (CMC) can be used as a stabilizer for directly acidified protein drinks (DAPDs). Use of pectin or CMC together with other polysaccharides and their impacts on product's rheological properties and tribological behavior are still largely unknown. This project investigated the impact of pectin and CMC, alone or in combination with guar gum, locust bean gum (LBG), and gellan gum when preparing DAPDs. The particle size distributions, rheological properties, tribological properties, and sensory properties were determined.

RESULTS

Pectin and CMC were dominating in the mixed system with other stabilizers. Increasing the concentration of hydrocolloids resulted in higher viscosity and better lubrication (lower friction coefficient). The sensory viscosity, smoothness, coating, and stickiness intensified as the concentration of hydrocolloids increased. The type and amount of hydrocolloids had a strong effect on the sensorial texture perception, but the flavor perception was only slightly affected.

CONCLUSION

Use of combined stabilizers may contribute to providing an effective viscosity enhancement without affecting the flavor in acidified milk beverages.

Measurement of molten chocolate friction under simulated tongue-palate kinematics: Effect of cocoa solids content and aeration

The perception of some food attributes is related to mechanical stimulation and friction experienced in the tongue-palate contact during mastication. This paper reports a new bench test to measure friction in the simulated tongue-palate contact. The test consists of a flat PDMS disk, representing the tongue loaded and reciprocating against a stationary lower glass surface representing the palate. The test was applied to molten chocolate samples with and without artificial saliva. Friction was measured over the first few rubbing cycles, simulating mechanical degradation of chocolate in the tongue-palate region. The effects of chocolate composition (cocoa solids content ranging between 28 ​wt% and 85 ​wt%) and structure (micro-aeration/non-aeration 0–15 ​vol%) were studied. The bench test clearly differentiates between the various chocolate samples. The coefficient of friction increases with cocoa solids percentage and decreases with increasing micro-aeration level. The presence of artificial saliva in the contact reduced the friction for all chocolate samples, however the relative ranking remained the same.

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Development of a reciprocating sliding friction test to mimic tongue-palate motion.

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Variations in friction coefficient depending on chocolate composition and structure.

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Higher cocoa content samples had higher friction coefficient.

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Friction coefficient decreased with aeration (0–15% vol).

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The presence of an artificial saliva film reduced chocolate friction.