Development of chewing in children from 12 to 48 months: longitudinal study of EMG patterns

Prolonged use of a soft diet during early growth and development alters feeding behavior and chewing kinematics in a young animal model

In infants and children with feeding and swallowing issues, modifying solid foods to form a liquid or puree is used to ensure adequate growth and nutrition. However, the behavioral and neurophysiological effects of prolonged use of this intervention during critical periods of postnatal oral skill development have not been systematically examined, although substantial anecdotal evidence suggests that it negatively impacts downstream feeding motor and coordination skills, possibly due to immature sensorimotor development. Using an established animal model for infant and juvenile feeding physiology, we leverage X-ray reconstruction of moving morphology to compare feeding behavior and kinematics between 12-week-old pigs reared on solid chow (control) and an age- and sex-matched cohort raised on the same chow softened to a liquid. When feeding on two novel foods, almond and apple, maintenance on a soft diet decreases gape cycle duration, resulting in a higher chewing frequency. When feeding on almonds, pigs in this group spent less time ingesting foods compared to controls, and chewing cycles were characterized by less jaw rotation about a dorsoventral axis (yaw) necessary for food reduction. There was also a reduced tendency to alternate chewing side with every chew during almond chewing, a behavioral pattern typical of pigs. These more pronounced impacts on behavior and kinematics during feeding on almonds, a tougher and stiffer food than apples, suggest that food properties mediate the behavioral and physiological impacts of early texture modification and that the ability to adapt to different food properties may be underdeveloped. In contrast, the limited effects of food texture modification on apple chewing indicate that such intervention/treatment does not alter feeding behavior of less challenging foods. Observed differences cannot be attributed to morphology because texture modification over the treatment period had limited impact on craniodental growth. Short-term impacts of soft-texture modification during postweaning development on feeding dynamics should be considered as potential negative outcomes of this treatment strategy.

Chewing skills in two and three year old children: Gender and age comparisons on an adapted version of the test of mastication and swallowing (TOMASS-C)

PURPOSE

Few assessment tools objectively measure chewing skills in the paediatric population. There is a need for assessment tools that use consistent foods so comparisons can be made between typically developing children and children with paediatric feeding disorders, and to measure the efficacy of treatment. The Test of Masticating and Swallowing Solids for adults (TOMASS) and children (TOMASS-C) are assessments that use a cracker as a consistent measure to assess chewing skills. Normative data exist for children over 4 years, however, no data are available for younger children. This study investigated age and gender-related differences in mastication skills in typically developing children aged 2-3 years when eating a cracker.

METHOD

Thirty participants aged 2;0-3;10 were assessed using an adapted version of the TOMASS-C. Participants were required to eat a single Arnott's Salada cracker, and the number of bites, masticatory cycles, swallows, and duration of time to finish the cracker were measured.

RESULT

Two-year-old children used more masticatory cycles and took longer to finish the cracker than 3-year-old children. There were no significant effects of age on the number of swallows and number of bites, and no significant differences between boys and girls.

CONCLUSION

This study provides preliminary normative data for chewing skills in children aged 2 and 3 years and confirms that the TOMASS-C is sensitive to developmental changes in mastication within this younger age range. These results expand our understanding of oral motor and chewing development in children.

Optimization of modularity during development to simplify walking control across multiple steps

Introduction

Walking in adults relies on a small number of modules, reducing the number of degrees of freedom that needs to be regulated by the central nervous system (CNS). While walking in toddlers seems to also involve a small number of modules when considering averaged or single-step data, toddlers produce a high amount of variability across strides, and the extent to which this variability interacts with modularity remains unclear.

Methods

Electromyographic activity from 10 bilateral lower limb muscles was recorded in both adults (n = 12) and toddlers (n = 12) over 8 gait cycles. Toddlers were recorded while walking independently and while being supported by an adult. This condition was implemented to assess if motor variability persisted with reduced balance constraints, suggesting a potential central origin rather than reliance on peripheral regulations. We used non-negative matrix factorization to model the underlying modular command with the Space-by-Time Decomposition method, with or without averaging data, and compared the modular organization of toddlers and adults during multiple walking strides.

Results

Toddlers were more variable in both conditions (i.e. independent walking and supported by an adult) and required significantly more modules to account for their greater stride-by-stride variability. Activations of these modules varied more across strides and were less parsimonious compared to adults, even with diminished balance constraints.

Discussion

The findings suggest that modular control of locomotion evolves between toddlerhood and adulthood as the organism develops and practices. Adults seem to be able to generate several strides of walking with less modules than toddlers. The persistence of variability in toddlers when balance constraints were lowered suggests a link with the ability to explore rather than with corrective mechanisms. In conclusion, the capacity of new walkers to flexibly activate their motor command suggests a broader range of possible actions, though distinguishing between modular and non-modular inputs remains challenging.

Long-lasting adverse effects of short-term stress during the suckling-mastication transition period on masticatory function and intraoral sensation in rats

Early-life stress affects brain development, eventually resulting in adverse behavioral and physical health consequences in adulthood. The present study assessed the hypothesis that short-term early-life stress during infancy before weaning, a period for the maturation of mastication and sleep, poses long-lasting adverse effects on masticatory function and intraoral sensations later in life.Rat pups were exposed to either maternal separation (MS) or intermittent hypoxia (IH-Infancy) for 6 h/day in the light/sleep phase from postnatal day (P)17 to P20 to generate "neglect" and "pediatric obstructive sleep apnea" models, respectively. The remaining rats were exposed to IH during P45-P48 (IH-Adult). Masticatory ability was evaluated based on the rats' ability to chew pellets and bite pasta throughout the growth period (P21-P70). Intraoral chemical and mechanical sensitivities were assessed using two-bottle preference drinking tests, and hind paw pain thresholds were measured in adulthood (after P60).No differences were found in body weight, grip force, and hind paw sensitivity in MS, IH-Infancy, and IH-Adult rats compared with naïve rats. Masticatory ability was lower in MS and IH-Infancy rats from P28 to P70 than in naïve rats. MS and IH-Infancy rats exhibited intraoral hypersensitivity to capsaicin and mechanical stimulations in adulthood. The IH-Adult rats did not display inferior masticatory ability or intraoral hypersensitivity.In conclusion, short-term early-life stress during the suckling-mastication transition period potentially causes a persistent decrease in masticatory ability and intraoral hypersensitivity in adulthood. The period is a "critical window" for the maturation of oral motor and sensory functions.

Neuromuscular adaptations of swallowing and speech in unilateral cerebral palsy: shared and distinctive traits

Our aims were to 1) examine the neuromuscular control of swallowing and speech in children with unilateral cerebral palsy (UCP) compared with typically developing children (TDC), 2) determine shared and separate neuromuscular underpinnings of the two functions, and 3) explore the relationship between this control and behavioral outcomes in UCP. Surface electromyography (sEMG) was used to record muscle activity from the submental and superior and inferior orbicularis oris muscles during standardized swallowing and speech tasks. The variables examined were normalized mean amplitude, time to peak amplitude, and bilateral synchrony. Swallowing and speech were evaluated using standard clinical measures. Sixteen children with UCP and 16 TDC participated (7-12 yr). Children with UCP demonstrated higher normalized mean amplitude and longer time to peak amplitude across tasks than TDC (P < 0.01; and P < 0.02) and decreased bilateral synchrony than TDC for swallows (P < 0.01). Both shared and distinctive neuromuscular patterns were observed between swallowing and speech. In UCP, higher upper lip amplitude during swallows was associated with shorter normalized mealtime durations, whereas higher submental bilateral synchrony was related to longer mealtime durations. Children with UCP demonstrate neuromuscular adaptations for swallowing and speech, which should be further evaluated for potential treatment targets. Furthermore, both shared and distinctive neuromuscular underpinnings between the two functions are documented.NEW & NOTEWORTHY Systematically studying the swallowing and speech of children with UCP is new and noteworthy. We found that they demonstrate neuromuscular adaptations for swallowing and speech compared with typically developing peers. We examined swallowing and speech using carefully designed tasks, similar in motor complexity, which allowed us to directly compare patterns. We found shared and distinctive neuromuscular patterns between swallowing and speech.

Shared and Separate Neuromuscular Underpinnings of Swallowing and Motor Speech Development in the School-Age Years

PURPOSE

Despite co-occurrence of swallowing and speech disorders in childhood, there is limited research on shared and separate neuromuscular underpinnings of these functions. The purpose of this study was to (a) compare neuromuscular control of swallowing and speech between younger and older children and (b) determine similarities and differences in neuromuscular control of swallowing and speech.

METHOD

Twenty-six typically developing children (thirteen 7- to 8-year-olds and thirteen 11- to 12-year-olds) completed this cross-sectional study. Neuromuscular control was evaluated using surface electromyography of submental muscles and superior and inferior orbicularis oris muscles during parallel tasks of swallowing and speech. Outcome measures included normalized mean amplitude, burst duration, time to peak amplitude, and bilateral synchrony, which were examined using mixed-effects models.

RESULTS

For normalized mean amplitude, burst duration, and time to peak amplitude, there were significant two- and three-way interactions between muscle group, task, and age group, indicating that older and younger children demonstrated different muscle activation patterns, and these patterns varied by muscle and task. No differences were noted between groups for bilateral synchrony. For parallel tasks, children demonstrated different magnitudes of normalized mean amplitude and time to peak amplitude of speech and swallowing. However, they demonstrated a similar pattern: increases in magnitude as task complexity increased.

CONCLUSIONS

Children continue to demonstrate refinement of their neuromuscular control of swallowing and speech between 7-8 and 11-12 years of age, and there are both shared and separate elements of neuromuscular control between these two vital functions. To improve generalizability of findings, future research should include longitudinal analysis of swallowing and speech development, as well as measures of central neurophysiology.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.23796258.

Acoustic and Kinematic Methods of Indexing Spatiotemporal Stability in Children With Developmental Language Disorder

PURPOSE

The spatiotemporal index (STI) is a standard metric for quantifying the stability and patterning of speech movements. The STI has often been applied to individual speech articulators, but an STI derived from the acoustic signal offers a composite and easily obtained measure that incorporates multiple components of the speech production complex. In this work, we examine the relationship between kinematic and acoustic STIs in children with and without developmental language disorder (DLD), with the aim of determining whether the acoustic and kinematic STIs reflect similar degrees of production variability.

METHOD

A total of 85 children with DLD and with typical language development (or typically developing [TD] children), aged 4-8 years, were studied. In this methodological article, two experiments were conducted: one deliberately selected because group differences were observed in the kinematic STI (i.e., sentence production) and one in which there were no group differences in the kinematic STI (i.e., nonword production). These two experiments are representative of speech stability studies. The aim was to determine whether the acoustic STI (i.e., amplitude envelope) results aligned with those obtained via the kinematic STI (i.e., lip motion).

RESULTS

In sentence production, most group differences aligned across kinematic and acoustic STI measures. The acoustic, but not the kinematic, STI showed higher variability in children with DLD compared with the 6-year-old TD group. In nonword production, neither the kinematic STI nor the acoustic STI differentiated children with DLD from TD children. In each experiment, the kinematic and acoustic STIs showed a moderate-to-strong correlation.

CONCLUSIONS

The kinematic and acoustic STIs assess different components of speech movement patterning. However, the relationship between acoustic and kinematic spatiotemporal stability is strong in two tasks of varying linguistic complexity in children with and without DLD. These findings are promising for future experimental work in this area.

Food oral processing and eating behavior from infancy to childhood: evidence on the role of food texture in the development of healthy eating behavior

Eating behaviors develop in early life and refine during childhood, shaping long-term food choice and dietary habits, which underpin optimum growth and health. The development of Food Oral Processing (FOP) is of major importance in the establishment of eating behaviors at two scale levels: for the initial acceptance of food texture and for the longer-term development of eating behaviors associated to food intake. To date, both processes have been studied as independent topics and the current review proposes a parallel vision on their development from the onset of complementary feeding to later childhood. Individual factors affecting these FOP-related behaviors as they relate to food texture acceptance are discussed, alongside examples of interventions aiming at modifying them. Opportunity to better consider food textures when designing foods for children is addressed. Altogether, the review demonstrates the critical role of food texture in the development of a child's FOP skills, eating habits, and dietary patterns. These scientific knowledges need to be considered for the development of healthier eating behavior. We identify research gaps that need to be addressed and highlight the need to design foods that can support the development of healthy oral processing and eating behaviors among infants and children.

Longitudinal electromyographic analysis of jaw-closing muscle activities during ingestive behaviors from pre-weaning to juvenile periods in rats

This longitudinal study investigated developmental changes in jaw-closing muscle activities during ingestive behaviors in rats. On postnatal day (P) 10, electromyography (EMG) electrodes were inserted into the masseter and temporalis muscles of rat pups. EMG activities were recorded for the following ingestive behaviors between P14 and P49: for suckling, including nipple attachment and rhythmic sucking on P14 and for pasta biting, pellet chewing, and milk licking between P21 and P49. Burst rhythms and muscle coordination (i.e., the correlation and time lag) between masseter and temporalis activities were assessed for each behavior. The burst rhythms of nipple attachment and rhythmic sucking on P14 were significantly slower than those of pasta biting, pellet chewing, and milk licking on P21. Muscle coordination differed between suckling on P14 and mastication and licking on P21. Between P21 and P49, increases were observed in burst rhythms for pasta biting and pellet chewing. The rate of increases in burst rhythms was higher for pasta biting than for pellet chewing. Muscle coordination between the two muscle activities for pasta biting did not significantly change between P21 and P49, whereas that for pellet chewing significantly changed between P21 and P24 and stabilized after P24. Burst rhythms for milk licking did not significantly change over time, while muscle coordination between the two muscle activities changed from agonist to antagonist muscle-like activity on approximately P35. The present results demonstrate that distinct patterns of rhythmic jaw-closing muscle activities emerge before weaning, they continue to change over time, and they exhibit unique developmental dynamics for each behavior after weaning.

Comprehensive Dental Treatment under General Anesthesia Improves Mastication Capability in Children with Early Childhood Caries-A One-Year Follow-Up Study

BACKGROUND

Using the granulometry of ready-to-swallow food boluses, this study investigated the evolution of masticatory capability of children with Early Childhood Caries (ECC) after comprehensive dental treatment under general anesthesia (GA).

METHODS

Sixteen children with ECC were assessed before and over one year after dental treatment under GA, in comparison with 12 children with a Healthy Oral State (HOS). Oral health criteria, quality of life, body mass index, and frequency of orofacial dysfunctions were recorded. Masticatory kinematic parameters and median food bolus particle size (D50) at swallowing were assessed while masticating raw carrot (CAR), cheese (CHS), and breakfast cereals (CER). The impact of posterior teeth extractions was analyzed.

RESULTS

Quality of life and orofacial functions improved after dental treatment. Chewing frequency for all three foods increased without reaching the values of children with HOS, while D50 values for CAR and CHS decreased. After one year, children with posterior teeth extractions exhibited higher D50 values for CAR and CHS than children with only conservative treatment. One third of children with ECC were overweight or obese.

CONCLUSIONS

Comprehensive dental treatment improved children's mastication, and their BMI subsequently increased. Links between mastication and nutrition should be investigated further in children.

Swallowing and Motor Speech Skills in Unilateral Cerebral Palsy: Novel Findings From a Preliminary Cross-Sectional Study

PURPOSE

Our purpose was to start examining clinical swallowing and motor speech skills of school-age children with unilateral cerebral palsy (UCP) compared to typically developing children (TDC), how these skills relate to each other, and whether they are predicted by clinical/demographic data (age, birth history, lesion type, etc.).

METHOD

Seventeen children with UCP and 17 TDC (7-12 years old) participated in this cross-sectional study. Feeding/swallowing skills were evaluated using the Dysphagia Disorder Survey (DDS) and a normalized measure of mealtime efficiency (normalized mealtime duration, i.e., nMD). Motor speech was assessed via speech intelligibility and speech rate measures using the Test of Children's Speech Plus. Analyses included nonparametric bootstrapping, correlation analysis, and multiple regression.

RESULTS

Children with UCP exhibited more severe (higher) DDS scores (p = .0096, Part 1; p = .0132, Part 2) and reduced speech rate than TDC (p = .0120). Furthermore, in children with UCP, total DDS scores were moderately negatively correlated with speech intelligibility (words: r = -.6162, p = .0086; sentences: r = -.60792, p = .0096). Expressive language scores were the only significant predictor of feeding and swallowing performance, and receptive language scores were the only significant predictor of motor speech skills.

CONCLUSIONS

Swallowing and motor speech skills can be affected in school-age children with UCP, with wide variability of performance also noted. Preliminary cross-system interactions between swallowing, speech, and language are observed and might support the complex relationships between these domains. Further understanding these relationships in this population could have prognostic and/or therapeutic value and warrants further study.

Evaluation of masticatory behavior and taste sensitivity after pacifier removal in preschool children: a 1-year follow-up

OBJECTIVE

The aim was to investigate the influence of pacifier removal on the development of masticatory function and taste sensitivity in preschool children.

METHODS

Sixty children (mean age 48.2 months) were divided into two groups: pacifier group (n = 28) and a control group (n = 32), which were evaluated and followed up for a period of 12 months (at baseline, 6 months, and 1 year). Masticatory and swallowing functions were assessed using the Mastication Observation and Evaluation (MOE) protocol and Orofacial Myofunctional Rating (MBGR), respectively. Detection thresholds for sucrose and urea were measured by the staircase method. The two-way ANOVA mixed model was used for time*group interaction analysis.

RESULTS

MOE scores improved significantly over time in both groups, although a significant difference between groups persisted after 1 year. On the other hand, swallowing scores were significantly different at baseline, but within 1 year, the scores were no longer different between groups. Chewing time and the number of cycles were not different between groups and both decreased after 1 year. Sucrose sensitivity was significantly greater in the control group at baseline and changed over time (p < 0.05), being no longer different between groups after 6 months. Bitter sensitivity did not differ over time nor between groups.

CONCLUSIONS

Detection threshold for sucrose differed significantly between children with and without pacifier habit at a mean age of 42 months. Total masticatory function did not self-correct after sucking habit removal within a 1-year period.

CLINICAL RELEVANCE

Children with pacifier habit showed important changes in masticatory function that did not self-correct 1 year after cessation of the habit, highlighting the need for prevention and habit interruption as early as possible.

Children who have more toothache-related behaviors have worse masticatory performance

Inadequate masticatory function can be linked to oral problems and result in functional limitation. In children, this function is extremely important for their development, and therefore efforts are made to keep it adequate. To evaluate whether dental pain-related behaviors are associated with masticatory performance (MP). A cross-sectional study was conducted with a sample of 123 children from 3 to 5 years old. Toothache was evaluated using the Dental Discomfort Questionnaire. Anthropometric data, predominant type of breathing, presence of malocclusion, number of posterior teeth cavitated by dental caries, and masticatory units were collected. MP was measured by the median size of the crushed particles (X₅₀ ) after 20 cycles of chewing the Optocal test material and was calculated with the Rosin-Rammler equation. Data analysis involved a description of variable frequencies, as well as simple and multiple linear regression, and a confidence level set at 95%. The mean scores of dental pain-related behaviors were 1.14 (±1.90) points, and the mean X₅₀ value was 3.96 mm (±1.34). In the multiple linear regression, a larger median size of the particles remained associated with a higher score of dental pain-related behaviors (β = +.81, p = .01); mouth breathing (β = +.22, p = .01); and a smaller number of masticatory units (β = -.22, p = .02). Greater dental pain-related behavior scores are associated with worse MP, regardless of the presence of associations with predominantly oral breathing and fewer chewing units.

In vitro models of gut digestion across childhood: current developments, challenges and future trends

The human digestion is a multi-step and multi-compartment process essential for human health, at the heart of many issues raised by academics, the medical world and industrials from the food, nutrition and pharma fields. In the first years of life, major dietary changes occur and are concomitant with an evolution of the whole child digestive tract anatomy and physiology, including colonization of gut microbiota. All these phenomena are influenced by child exposure to environmental compounds, such as drugs (especially antibiotics) and food pollutants, but also childhood infections. Due to obvious ethical, regulatory and technical limitations, in vivo approaches in animal and human are more and more restricted to favor complementary in vitro approaches. This review summarizes current knowledge on the evolution of child gut physiology from birth to 3 years old regarding physicochemical, mechanical and microbial parameters. Then, all the available in vitro models of the child digestive tract are described, ranging from the simplest static mono-compartmental systems to the most sophisticated dynamic and multi-compartmental models, and mimicking from the oral phase to the colon compartment. Lastly, we detail the main applications of child gut models in nutritional, pharmaceutical and microbiological studies and discuss the limitations and challenges facing this field of research.

Does the duration and frequency of dummy (pacifier) use affect the development of speech?

BACKGROUND

The current literature suggests a link between dummy (or pacifier) use and a number of both positive and detrimental consequences. Positive consequences include soothing effect and protection from sudden infant death syndrome (SIDS), while negative ones include increased risk of otitis media and dental malformation. However, there is little research surrounding the impact of dummy use on the development of speech sounds.

AIMS

To investigate whether duration (in number of months) and frequency per day of dummy use have an individual or combined effect on the development of a child's speech, and if so, in what way.

METHODS & PROCEDURES

A total of 100 British-English children aged 24-61 months and growing up in the UK were recruited through nurseries, playgroups and by word of mouth. Their parents were asked to complete a questionnaire about the duration and frequency of dummy use and factors known to influence the development of speech. Following this, the children's speech was assessed using the phonology section of the Diagnostic Evaluation of Articulation and Phonology (DEAP). Analysis of the DEAP was conducted to determine the percentage of consonants correct, number of age-appropriate, delayed and atypical errors. Dummy use and speech outcome measures were then analysed qualitatively and quantitatively using mean and median group comparisons alongside multivariate generalized least squares and generalized negative binomial modelling approaches to test for significant associations.

OUTCOMES & RESULTS

The results showed that the majority of speech outcomes are not significantly associated with dummy use, however measured, in bivariate or multivariate analyses. However, there is a significant association between increased atypical errors and greater frequency of daytime dummy use. This association is strengthened by restricted sampling within the younger members of the sample, with this association not observable within children older than 38 months, the median sample age.

CONCLUSIONS & IMPLICATIONS

The evidence base for any effects of dummy use on speech is very small. Dummy use may increase the number of atypical speech errors a young child makes. However, only the frequency of daytime use seems relevant, not the duration or night-time use, and these errors may resolve over time. What this paper adds What is already known on this subject The use of a dummy with infants in Western countries is comparatively high (between 36-85%). A number of positive and detrimental consequences of dummy use have been documented in the literature; however, research on the effect of dummy use on speech development is significantly lacking. Past studies have included small sample sizes or used single measures of speech outcomes, which may not be specific enough to reveal how speech may be affected. Many speech and language therapists speculate that the use of a dummy could be contributing to many of the conditions they treat, yet this claim remains largely unsubstantiated. Clinical implications of this study The study suggests that only prolonged use of a dummy over several hours and during the day may start to show any impact on speech; even then, professionals need to be aware that the evidence base for any speech effects is very small. Clinicians and other professionals who parents consult on dummy use should make sure to provide both the pros and cons of dummy use, in order to enable parents to make an informed decision.

Factors Associated With Food Texture Acceptance in 4- to 36-Month-Old French Children: Findings From a Survey Study

Food texture plays an important role in food acceptance by young children, especially during the complementary feeding period. The factors driving infant acceptance of a variety of food textures are not well-known. This study summarizes maternal reports of children's ability to eat foods of different textures (here: acceptance) and associated factors. Mothers of 4- to 36-month-old children (n = 2,999) answered an online survey listing 188 food-texture combinations representing three texture levels: purees (T1), soft small pieces (T2), hard/large pieces, and double textures (T3). For each offered combination, they reported whether it was spat out or eaten with or without difficulty by the child. A global food texture acceptance score (TextAcc) was calculated for each child as an indicator of their ability to eat the offered textured foods. The results were computed by age class from 4-5 to 30-36 months. The ability to eat foods without difficulty increased with age and was ranked as follows: T1> T2 > T3 at all ages. TextAcc was positively associated with exposure to T2 (in the age classes between 6 and 18 months old) and T3 (6-29 months) and negatively associated with exposure to T1 (9-36 months). Children's developmental characteristics, as well as maternal feeding practices and feelings with regard to the introduction of solids, were associated with texture acceptance either directly or indirectly by modulating exposure. Children's ability to eat with their fingers, gagging frequency, and to a lesser extent, dentition as well as maternal feelings with regard to the introduction of solids were the major factors associated with acceptance. This survey provides a detailed description of the development of food texture acceptance over the complementary feeding period, confirms the importance of exposure to a variety of textures and identifies a number of additional person-related associated factors.

Observations on the growth of temporalis muscle: A 3D CT imaging study

This study investigates the hypothesis that there is, during childhood, a disproportionate age-related expansion of the origin of temporalis muscle compared to the growth of the underlying skull. Lateral projections of 50 randomly selected 3D reformatted computerized tomographic (CT) scans (yielding 100 temporalis muscles) of children aged >0.6 to 15 years scanned for conditions that did not affect the shape of their head or face were windowed to provide the optimum delineation of temporalis muscle against the underlying bone. Vertical and anterior-posterior measurements of the muscle made independently by two observers were compared with those of the skull along the same planes. The development of the anterior temporal crest was also assessed. The intraclass correlation coefficient for differences in the measurements made by each observer ranged from good to excellent. The muscle and skull measurements were used to produce a ratio of muscle-to-skull lengths in both vertical and horizontal planes. Analysis of these ratios showed a statistically significant increase in the vertical reach of temporalis with age (Pearson correlation coefficient (R) =0.7826; p < 0.05) compared to the growth of the skull along the planes chosen for the study-but less so for its horizontal reach (R = 0.5073. p < .001). There were no significant differences between right/left or male/female measurements. There was also a substantial level of agreement between both observers in their assessment of the development of the temporal crest. The mean age of children in whom a fully formed temporal crest could be identified (10.6 years) was significantly greater (p < 0.001) than that of the 38 remaining subjects (6.0 years). These results confirm that there is, in response to increased masticatory/dietary demands during childhood, a disproportionate increase in the vertical and (to a lesser extent) horizontal reach of temporalis muscle over its origin from the temporal, frontal, sphenoid, and parietal bones compared the growth of the skull. It is proposed that surgical interference with this normal process is responsible for the soft tissue component of late-developing deformity that can occur following early (at 6-18 months of age) operations for the correction of trigonocephalic head shape associated with metopic synostosis.

Modulation of Intermuscular Beta Coherence in Different Rhythmic Mandibular Behaviors

Introduction

Jaw movement during chewing and speech is facilitated by neural activation patterns for opening and closing movements of the mandible. This study investigated anatomic- and task-dependent differences in intermuscular coherence (IMC) and their association with the parameters of jaw muscle activity using surface electromyography (sEMG).

Methods

We recorded sEMG activation from bilateral and ipsilateral jaw-closing muscle pairs during non-nutritive and nutritive chewing, and during a syllable repetition task. IMC and cross-correlational analyses between bilateral and ipsilateral muscle pairs were performed.

Results

Intermuscular coherence in the beta band was statistically significant between agonist jaw-closing muscle pairs, with beta IMC weaker for rapid syllable repetition compared to chewing tasks. Cross-correlational analysis of muscle co-activation, as well as sEMG burst amplitude, was positively associated with beta IMC strength.

Discussion

Beta IMC was influenced heavily by task-dependent behavioral goals and physiologic demands, which was interpreted as evidence of shared neural drive among jaw-closing muscles.

Turkish Version of the Mastication Observation and Evaluation (MOE) Instrument: A Reliability and Validity Study in Children

The Mastication Observation and Evaluation (MOE) instrument is an objective assessment of the chewing process in children. This study aimed to translate the MOE into Turkish and to test its reliability and validity in children with cerebral palsy (CP). A total of 53 children with CP and 27 typical children were included in the study. The MOE was translated from Dutch into Turkish by using the forward, backward, forward translation method. The internal consistency, intra- and inter-observer reliability, criterion, and discriminant validity of the Turkish version of the MOE (T-MOE) were investigated. Internal consistency was excellent with a Cronbach's alpha value of 0.98. The Intraclass correlation coefficient ranged from 0.89 to 0.97 for intra-rater reliability and from 0.86 to 0.94 for inter-rater reliability. The median score from Karaduman Chewing Performance Scale (KCPS) was 7 (min = 1, max = 8). All of the items in the T-MOE and the total T-MOE score had a negative and strong correlation with the KCPS score. Typical children without chewing disorders had greater T-MOE scores than the children with CP suffering from chewing disorders (p < 0.01). The T-MOE is a reliable and valid instrument for evaluating the observed oral motor behaviors of chewing function in children. It can be used in clinical practice and research.Clinical trial number: NCT03811353.

Masticatory behavior for different solid foods in preschool children according to their oral state

Gradual introduction of solid foods in early childhood takes part in the maturation of mastication. The impact of any oral state alteration on food oral processing development is poorly documented for this age group. This study investigated the masticatory behavior in 3 to 6 year-old children with or without early childhood caries (ECC) for three solid foods of different textures. Twenty-one children with healthy oral state and 23 children with severe ECC were observed during complete mastication of calibrated samples of raw carrot, cheese and breakfast cereals. Food refusals and kinematic parameters (Ti: chewing time, Nc: number of cycles and Fq: chewing frequency) were used to assess children masticatory behavior. Oral Health-related Quality of Life and orofacial dysfunctions were evaluated using, respectively the early childhood oral health impact scale (ECOHIS) and the Nordic orofacial dysfunction test screening (NOT-S). Children suffering from ECC exhibited significantly higher ECOHIS and NOT-S scores, in particular for the mastication domain. Accordingly, lower chewing frequencies values were recorded in children with ECC (i.e., carrot Fq: 1.21 ± 0.20 vs 1.35 ± 0.22, p ≤ 0.01), as well as more frequent refusals for carrots. Kinematic parameters were shown to be repeatable in all children for successive samples of the same food, and tended to vary depending on the proposed food. Some masticatory behavior regulation according to food properties could already be present in preschool children. Children with ECC developed alternative behavioral strategies to overcome feeding difficulties. Further studies should investigate food bolus properties according to oral health, as well as nutritional issues. PRACTICAL APPLICATIONS: During childhood, the way solid foods are processed in the oral cavity to be safely swallowed and then digested in available nutrients, is poorly documented. In this study, preschool children have been shown to repeatedly adapt their masticatory behavior to a given food. The collection of various food boli as recorded at the moment of swallowing could then be considered in further food bolus properties research investigations. Moreover, this study suggested that children with altered dentition modified their masticatory kinematic parameters and developed alternative strategies, including food or texture selection, to overcome their feeding difficulties. The development of a mastication evaluation protocol could help medical professionals to detect children masticatory deficiencies and then propose diet adaptations. Considering the importance of food diversity in mastication development and maturation, food industries may consider to develop a range of texture adapted foods for young children, especially designed to gradually rehabilitate the masticatory function.

A new masticatory performance assessment method for infants: A feasibility study

This study evaluated the feasibility of assessing masticatory performance in infants and toddlers. Four groups of healthy children (n = 97, 42 girls and 55 boys) participated in the study: two study groups (SG) followed at 6, 8, and 10 months old (MO) or at 12, 15, and 18 MO, and two control groups (CG) of respectively 10 and 18 MO children. Masticatory performance was determined from children's ability to comminute a model gel during videotaped lab measurements. The gel was inserted in a mesh feeder and offered to the child for a 60s oral processing duration, then gel particles were collected from the feeder and photographed. Resulting gel breakdown was assessed from the characterization of the area and number of formed particles. Children strategy to orally process the gel (sucking vs. biting/chewing) was evaluated from video recordings. Children's compliance (acceptance of the feeder in the mouth for the expected duration) was average (51%) overall. It decreased from 1 year of age and was higher in SG than in CG. The number and area of gel particles formed under oral processing increased significantly with age, demonstrating an increase in children masticatory performance as they grew up. Median particles area was positively associated with sucking behavior and negatively associated with biting/chewing. The association with teeth emergence was not significant. In conclusion, the proposed method is relevant for quantifying the development of early masticatory performance in children who accept to hold the feeder in their mouth. PRACTICAL APPLICATIONS: In this article, a method to easily quantify masticatory performance in young children aged 6-18 MO was evaluated. The method is based on a feeder and could be used for collecting boluses, as an alternative to the chew-and-spit method when it is unfeasible. Children's compliance to the method and the impact of previous study participation on compliance to the protocol are detailed, giving thus a rationale for an optimal application of this method in future experiments. Finally, the determination of masticatory performance as a function of age thanks to this method could contribute to the understanding of food oral processing and food texture acceptance in childhood in future studies.

Basic choking education to improve parental knowledge

OBJECTIVE

To evaluate the effect of an educational intervention on parental knowledge of choking hazards and prevention.

METHODS

A quasi experimental study was performed utilizing an internet based educational video intervention for parents with a child 6 months to 4 years old presenting to a Pediatric Otolaryngology clinic at a Level 1 pediatric hospital. Following the clinic visit, participants were sent a choking video (intervention) or general safety video (control) with a pretest and posttest knowledge survey (via email). An additional posttest knowledge survey was sent 30 days later as a surrogate measure for knowledge retained over time. Frequencies, chi square test, Independent t-test and McNemar's test were used for statistical analyses.

RESULTS

202 participants viewed the video and completed both the pretest and immediate posttest knowledge survey. Average change in total knowledge scores from the pretest to immediate posttest was statistically significant between the intervention (μ = 1.88, σ = 1.20) and control group (μ = 0.14, σ = 1.05); t (200) = -10.99, P < .001. This finding was consistent when assessing change from the pretest to 30 day posttest between the intervention (μ = 1.41, σ = 1.32) and control group (μ = 0.17, σ = 1.41); t (118) = -4.95, P < .001. A majority of the knowledge questions (5 of 7) showed a significant change in score from the pretest to immediate posttest (P = .001-.027). Additional analyses revealed accuracy on 4 of 7 knowledge questions significantly changed from the pretest to 30 day later posttest (P < .001- .002).

CONCLUSION

The brief educational video overall improved parental knowledge of choking hazards and prevention immediately after the video and 30 days later. Importantly, improved parental knowledge may decrease rates of choking among children.

Early human motor development: From variation to the ability to vary and adapt

This review summarizes early human motor development. From early fetal age motor behavior is based on spontaneous neural activity: activity of networks in the brainstem and spinal cord that is modulated by supraspinal activity. The supraspinal activity, first primarily brought about by the cortical subplate, later by the cortical plate, induces movement variation. Initially, movement variation especially serves exploration; its associated afferent information is primarily used to sculpt the developing nervous system, and less to adapt motor behavior. In the next phase, beginning at function-specific ages, movement variation starts to serve adaptation. In sucking and swallowing, this phase emerges shortly before term age. In speech, gross and fine motor development, it emerges from 3 to 4 months post-term onwards, i.e., when developmental focus in the primary sensory and motor cortices has shifted to the permanent cortical circuitries. With increasing age and increasing trial-and-error exploration, the infant improves its ability to use adaptive and efficicient forms of upright gross motor behavior, manual activities and vocalizations belonging to the native language.

Differing structural properties of foods affect the development of mandibular control and muscle coordination in infants and young children

The development of chewing is an essential motor skill that is continually refined throughout early childhood. From a motor control perspective, the advancement of textures is dependent upon the fit between a child's oral anatomic and motor system and food properties. The purpose of this exploratory study is to identify age-related changes in chewing motor coordination and control and to determine if these changes are associated with the differing structural properties of solid foods, as well as to explore the role of explanatory variables such as the emergence of teeth and bite force. The masticatory muscle coordination (i.e., coupling of synergistic and antagonistic muscle pairs) and control (i.e., speed, displacement, chewing rate, duration, and number of chews) of fifty children were assessed cross-sectionally at five ages: 9-, 12-, 18-, 24-, and 36-months using electromyography (EMG) and 3D optical motion capture while children ate three foods that had differing structural properties. The results of this study found that children made gains in their chewing motor control (decreased duration of chewing sequences and lateral jaw displacement) and coordination (improved jaw muscle coupling) throughout this period. The structural differences in foods also affected chewing performance at all ages. These preliminary findings suggest that some solid textures are better adapted for immature mandibular control than others and that the development of chewing is a protracted process that may be impacted by the emergence of teeth and changes to bite force.

Special Considerations for the Pediatric Population Relating to a Swallow Screen Versus Clinical Swallow or Instrumental Evaluation

Careful consideration should be taken to determine how a swallow screen could be implemented in the pediatric population. A variety of factors to be considered include: age, developmental level, feeding experience of the child, diagnosis, the status of the child's dysphagia, and the setting where the patient is treated. A swallow screen might be feasible in specific situations in the pediatric population to identify aspiration risk in those with a change in normal swallow status. Yet, more research is needed to improve the accurate identification for the pediatric population of aspiration risk and other signs of dysphagia that warrant an instrumental assessment. While risk for aspiration is a concern in this population, it is not the only concern due to the dynamic changes in feeding and swallowing performance that occur throughout childhood. These dynamic changes require a thorough clinical observation that neither a swallow screening nor instrumental assessment can provide the clinician. Thus, the clinical swallow evaluation (CSE) remains the most comprehensive tool available to assess oral feeding skill development and function, as well as, to identify risk factors for not only aspiration, but for other aspects of dysphagia, which may warrant an instrumental assessment.

Speech-like rhythm in a voiced and voiceless orangutan call

The evolutionary origins of speech remain obscure. Recently, it was proposed that speech derived from monkey facial signals which exhibit a speech-like rhythm of ∼5 open-close lip cycles per second. In monkeys, these signals may also be vocalized, offering a plausible evolutionary stepping stone towards speech. Three essential predictions remain, however, to be tested to assess this hypothesis' validity; (i) Great apes, our closest relatives, should likewise produce 5Hz-rhythm signals, (ii) speech-like rhythm should involve calls articulatorily similar to consonants and vowels given that speech rhythm is the direct product of stringing together these two basic elements, and (iii) speech-like rhythm should be experience-based. Via cinematic analyses we demonstrate that an ex-entertainment orangutan produces two calls at a speech-like rhythm, coined “clicks” and “faux-speech.” Like voiceless consonants, clicks required no vocal fold action, but did involve independent manoeuvring over lips and tongue. In parallel to vowels, faux-speech showed harmonic and formant modulations, implying vocal fold and supralaryngeal action. This rhythm was several times faster than orangutan chewing rates, as observed in monkeys and humans. Critically, this rhythm was seven-fold faster, and contextually distinct, than any other known rhythmic calls described to date in the largest database of the orangutan repertoire ever assembled. The first two predictions advanced by this study are validated and, based on parsimony and exclusion of potential alternative explanations, initial support is given to the third prediction. Irrespectively of the putative origins of these calls and underlying mechanisms, our findings demonstrate irrevocably that great apes are not respiratorily, articulatorilly, or neurologically constrained for the production of consonant- and vowel-like calls at speech rhythm. Orangutan clicks and faux-speech confirm the importance of rhythmic speech antecedents within the primate lineage, and highlight potential articulatory homologies between great ape calls and human consonants and vowels.

Data-driven subclassification of speech sound disorders in preschool children

PURPOSE

The purpose of the study was to determine whether distinct subgroups of preschool children with speech sound disorders (SSD) could be identified using a subgroup discovery algorithm (SUBgroup discovery via Alternate Random Processes, or SUBARP). Of specific interest was finding evidence of a subgroup of SSD exhibiting performance consistent with atypical speech motor control.

METHOD

Ninety-seven preschool children with SSD completed speech and nonspeech tasks. Fifty-three kinematic, acoustic, and behavioral measures from these tasks were input to SUBARP.

RESULTS

Two distinct subgroups were identified from the larger sample. The 1st subgroup (76%; population prevalence estimate = 67.8%-84.8%) did not have characteristics that would suggest atypical speech motor control. The 2nd subgroup (10.3%; population prevalence estimate = 4.3%-16.5%) exhibited significantly higher variability in measures of articulatory kinematics and poor ability to imitate iambic lexical stress, suggesting atypical speech motor control. Both subgroups were consistent with classes of SSD in the Speech Disorders Classification System (SDCS; Shriberg et al., 2010a).

CONCLUSION

Characteristics of children in the larger subgroup were consistent with the proportionally large SDCS class termed speech delay; characteristics of children in the smaller subgroup were consistent with the SDCS subtype termed motor speech disorder-not otherwise specified. The authors identified candidate measures to identify children in each of these groups.

The evolution of speech: vision, rhythm, cooperation

A full account of human speech evolution must consider its multisensory, rhythmic, and cooperative characteristics. Humans, apes, and monkeys recognize the correspondence between vocalizations and their associated facial postures, and gain behavioral benefits from them. Some monkey vocalizations even have a speech-like acoustic rhythmicity but lack the concomitant rhythmic facial motion that speech exhibits. We review data showing that rhythmic facial expressions such as lip-smacking may have been linked to vocal output to produce an ancestral form of rhythmic audiovisual speech. Finally, we argue that human vocal cooperation (turn-taking) may have arisen through a combination of volubility and prosociality, and provide comparative evidence from one species to support this hypothesis.

Validity and reliability of the Mastication Observation and Evaluation (MOE) instrument

The Mastication Observation and Evaluation (MOE) instrument was developed to allow objective assessment of a child's mastication process. It contains 14 items and was developed over three Delphi rounds. The present study concerns the further development of the MOE using the COSMIN (Consensus based Standard for the Selection of Measurement Instruments) and investigated the instrument's internal consistency, inter-observer reliability, construct validity and floor and ceiling effects. Consumption of three bites of bread and biscuit was evaluated using the MOE. Data of 59 healthy children (6-48 mths) and 38 children (bread) and 37 children (biscuit) with cerebral palsy (24-72 mths) were used. Four items were excluded before analysis due to zero variance. Principal Components Analysis showed one factor with 8 items. Internal consistency was >0.70 (Chronbach's alpha) for both food consistencies and for both groups of children. Inter-observer reliability varied from 0.51 to 0.98 (weighted Gwet's agreement coefficient). The total MOE scores for both groups showed normal distribution for the population. There were no floor or ceiling effects. The revised MOE now contains 8 items that (a) have a consistent concept for mastication and can be scored on a 4-point scale with sufficient reliability and (b) are sensitive to stages of chewing development in young children. The removed items are retained as part of a criterion referenced list within the MOE.

Facial expressions and the evolution of the speech rhythm

In primates, different vocalizations are produced, at least in part, by making different facial expressions. Not surprisingly, humans, apes, and monkeys all recognize the correspondence between vocalizations and the facial postures associated with them. However, one major dissimilarity between monkey vocalizations and human speech is that, in the latter, the acoustic output and associated movements of the mouth are both rhythmic (in the 3- to 8-Hz range) and tightly correlated, whereas monkey vocalizations have a similar acoustic rhythmicity but lack the concommitant rhythmic facial motion. This raises the question of how we evolved from a presumptive ancestral acoustic-only vocal rhythm to the one that is audiovisual with improved perceptual sensitivity. According to one hypothesis, this bisensory speech rhythm evolved through the rhythmic facial expressions of ancestral primates. If this hypothesis has any validity, we expect that the extant nonhuman primates produce at least some facial expressions with a speech-like rhythm in the 3- to 8-Hz frequency range. Lip smacking, an affiliative signal observed in many genera of primates, satisfies this criterion. We review a series of studies using developmental, x-ray cineradiographic, EMG, and perceptual approaches with macaque monkeys producing lip smacks to further investigate this hypothesis. We then explore its putative neural basis and remark on important differences between lip smacking and speech production. Overall, the data support the hypothesis that lip smacking may have been an ancestral expression that was linked to vocal output to produce the original rhythmic audiovisual speech-like utterances in the human lineage.

Alterações no controle motor mandibular e cervical de crianças com paralisia cerebral

Objetivo: analisar a atividade elétrica dos músculos Temporal e Masseter e o padrão de postura e movimento de cabeça e mandíbula de crianças com Paralisia Cerebral (PC).Métodos: a amostra deste estudo compreendeu 32 voluntários com PC espástica e com Desenvolvimento Típico, com a faixa etária de 7 a 13 anos de idade, caracterizados com base na Classificação de Angle e Critério de Diagnóstico para Pesquisa das Disfunções Temporomandibulares (RDC/TMD). De forma simultânea, foram avaliadas a postura e movimentação da cabeça e mandíbula e a atividade elétrica dos músculos Temporal e Masseter por meio da cinemática e eletromiografia.Resultados: a PC não foi associada a presença de DTM ou com a alteração da oclusão dentária. No grupo PC, foi observada maior assimetria do músculo temporal (p<0.05), maior extensão da cabeça na máxima abertura da boca (p<0.05), maior amplitude de extensão da cabeça (p<0.01) e maior amplitude de projeção anterior da cabeça (p<0.05).Conclusão: a maior assimetria na atividade muscular, a maior extensão e projeção anterior da cabeça durante o ciclo mastigatório podem ser causas das desordens da função motora oral das crianças com PC.

Anatomical, functional, physiological and behavioural aspects of the development of mastication in early childhood

Mastication efficiency is defined as the efficiency of crushing food between the teeth and manipulating the resulting particles to form a swallowable food bolus. It is dependent on the orofacial anatomical features of the subject, the coordination of these anatomical features and the consistency of the food used during testing. Different measures have been used to indirectly quantify mastication efficiency as a function of children's age such as observations, food bolus characterisation, muscle activity measurement and jaw movement tracking. In the present review, we aim to describe the changes in the oral physiology (e.g. bone and muscle structure, teeth and soft tissues) of children and how these changes are associated with mastication abilities. We also review previous work on the effect of food consistency on children's mastication abilities and on their level of texture acceptance. The lack of reference foods and differences in testing methodologies across different studies do not allow us to draw conclusions about (1) the age at which mastication efficiency reaches maturity and (2) the effect of food consistency on the establishment of mature mastication efficiency. The effect of food consistency on the development of children's mastication efficiency has not been tested widely. However, both human and animal studies have reported the effect of food consistency on orofacial development, suggesting that a diet with harder textures enhances bone and muscle growth, which could indirectly lead to better mastication efficiency. Finally, it was also reported that (1) children are more likely to accept textures that they are able to manipulate and (2) early exposure to a range of textures facilitates the acceptance of foods of various textures later on. Recommending products well adapted to children's mastication during weaning could facilitate their acceptance of new textures and support the development of healthy eating habits.

Associação da atividade mastigatória com a função motora ampla, espasticidade e classificação topográfica na paralisia cerebral

OBJETIVO: verificar a existência de associação entre o grau de espasticidade, o nível de função motora ampla e a classificação topográfica de voluntários com PC com parâmetros de amplitude e tempo da ativação eletromiográfica dos músculos temporal (TA) e masseter (MA). MÉTODOS: a atividade muscular durante a tarefa de mastigação foi avaliada em quinze voluntários com PC. Os instrumentos clínicos utilizados foram: a Escala Modificada de Ashworth para espasticidade, o Sistema de Classificação de Função Motora Ampla (GMFCS) para função motora ampla. Foram analisados os parâmetros de simetria muscular e tempo do período ativo e inativo do ciclo mastigatório. RESULTADOS: durante o ciclo mastigatório observou-se associação entre o nível de função motora ampla e a simetria do MA, entre o maior grau de espasticidade e a diminuição do período inativo e aumento do período ativo e entre a classificação topográfica e a simetria do MA e do TA. CONCLUSÃO: a simetria e o tempo da atividade dos músculos TA e MA devem ser considerados durante a terapia da função motora oral na PC.

Effect of early undernutrition on masticatory morphophysiology: review of the literature

INTRODUCTION

Certain periods of development of the nervous system are critically vulnerable to environmental insults because of the processes involved that cycle very quickly. Morphologic and functional development of mastication occurs coincidently during these stages. Early environmental insults during critical periods can cause permanent effects on both structures and functions of organic systems that can have lasting repercussions in adulthood.

OBJECTIVE

In this study, we investigated, through a literature review, the possible effects of perinatal calorie and/or protein low diet on structural and physiological development of mastication.

DESIGN

A systematic literature search was conducted from in the PUBMED electronic database. In collecting literature we used the keywords: "undernutrition" and "stomatognathic system". Criteria used in the selection of articles for inclusion were: studies evaluating the effects of perinatal calorie and/or protein low diet on masticatory morphology and function. Exclusion criteria included, short communications and nonavailability in full text format.

CONCLUSION

Undernutrition during critical periods of life causes changes in the key structures of masticatory function. This fact can affect the selection of essential nutrients, thereby interfering with the process of satiation.

Cineradiography of monkey lip-smacking reveals putative precursors of speech dynamics

A key feature of speech is its stereotypical 5 Hz rhythm. One theory posits that this rhythm evolved through the modification of rhythmic facial movements in ancestral primates. If the hypothesis has any validity, then a comparative approach may shed some light. We tested this idea by using cineradiography (X-ray movies) to characterize and quantify the internal dynamics of the macaque monkey vocal tract during lip-smacking (a rhythmic facial expression) versus chewing. Previous human studies showed that speech movements are faster than chewing movements, and the functional coordination between vocal tract structures is different between the two behaviors. If rhythmic speech evolved through a rhythmic ancestral facial movement, then one hypothesis is that monkey lip-smacking versus chewing should also exhibit these differences. We found that the lips, tongue, and hyoid move with a speech-like 5 Hz rhythm during lip-smacking, but not during chewing. Most importantly, the functional coordination between these structures was distinct for each behavior. These data provide empirical support for the idea that the human speech rhythm evolved from the rhythmic facial expressions of ancestral primates.

Monkey lipsmacking develops like the human speech rhythm

Across all languages studied to date, audiovisual speech exhibits a consistent rhythmic structure. This rhythm is critical to speech perception. Some have suggested that the speech rhythm evolved de novo in humans. An alternative account--the one we explored here--is that the rhythm of speech evolved through the modification of rhythmic facial expressions. We tested this idea by investigating the structure and development of macaque monkey lipsmacks and found that their developmental trajectory is strikingly similar to the one that leads from human infant babbling to adult speech. Specifically, we show that: (1) younger monkeys produce slower, more variable mouth movements and as they get older, these movements become faster and less variable; and (2) this developmental pattern does not occur for another cyclical mouth movement--chewing. These patterns parallel human developmental patterns for speech and chewing. They suggest that, in both species, the two types of rhythmic mouth movements use different underlying neural circuits that develop in different ways. Ultimately, both lipsmacking and speech converge on a ~5 Hz rhythm that represents the frequency that characterizes the speech rhythm of human adults. We conclude that monkey lipsmacking and human speech share a homologous developmental mechanism, lending strong empirical support to the idea that the human speech rhythm evolved from the rhythmic facial expressions of our primate ancestors.

A kinematic description of the temporal characteristics of jaw motion for early chewing: preliminary findings

PURPOSE

The purpose of this investigation was to describe age- and consistency-related changes in the temporal characteristics of chewing in typically developing children between the ages of 4 and 35 months and adults using high-resolution optically based motion capture technology.

METHOD

Data were collected from 60 participants (48 children, 12 adults) across 5 age ranges (beginners, 7 months, 12 months, 35 months, and adults); each age group included 12 participants. Three different food consistencies were trialed as appropriate. The data were analyzed to assess changes in chewing rate, chewing sequence duration, and estimated number of chewing cycles.

RESULTS

The results revealed both age- and consistency-related changes in chewing rate, sequence duration, and estimated number of chewing cycles, with consistency differences affecting masticatory timing in children as young as 7 months of age. Chewing rate varied as a function of age and consistency, and chewing sequence duration was shorter for adults than for children regardless of consistency type. In addition, the results from the estimated number of chewing cycles measure suggest that chewing effectiveness increased with age; this measure was also dependent on consistency type.

CONCLUSIONS

The findings suggest that the different temporal chewing variables follow distinct developmental trajectories and are consistency dependent in children as young as 7 months of age. Clinical implications are detailed.

EMG BioanalyzerBR para a análise de sinais eletromiográficos na deglutição

OBJETIVO: descrever as etapas de construção do EMG BioanalyzerBR (versão 1.0) e demonstrar a sua aplicabilidade na análise de parâmetros fornecidos pela eletromiografia de superfície (EMGs). MÉTODOS: trata-se de um estudo descritivo do software de análise desenvolvido para analisar parâmetros obtidos na eletromiografia de superfície de músculos envolvidos na deglutição. Este software foi escrito em um ambiente de desenvolvimento utilizado por pesquisadores do mundo todo, de fácil acessibilidade e programação: o SCILAB. RESULTADOS: esta ferramenta se mostrou eficaz para a análise e transferência de dados nos registros curtos, contendo em média 10s de duração, porém para registros mais longos com duração maior que 20s apresentou falhas que não prejudicaram o cálculo após algumas tentativas. CONCLUSÃO: apesar das dificuldades, O EMG BioanalyzerBR possibilitou a realização das marcações canal por canal e quantas marcações fossem necessárias de forma simultânea,e desta forma a tabulação dos dados ficou mais rápida e com margem de falhas humanas reduzidas, porém com necessidade de aprimoramentos para a versão 2.0.

Sexual dimorphism of the human mandible and its association with dental development

The present study investigates whether the human mandible is sexually dimorphic during early postnatal development and whether early dimorphic features persist during subsequent ontogeny. We also examine whether mandibular dimorphism is linked to dimorphism of dental development. Dense CT-derived mandibular meshes of 84 females and 75 males, ranging from birth to adulthood, were analyzed using geometric morphometric methods. On the basis of the specimen's chronological ages and mineralization stages of the deciduous and permanent teeth, we compute dental age as proxy for dental development by the additive conjoint measurement method. By birth, males have, on average, more advanced age-specific shapes than females. However, sex differences decrease quickly as females catch up via a different association between shape and size. This leads to an almost complete reduction of sexual dimorphism between the ages of 4 and 14. From puberty to adulthood, males are characterized by allometric shape changes while the shape of the female mandible continues to change even after size has ceased to increase. Dimorphism of dental maturation becomes visible only at puberty. Sexual dimorphism, concentrated at the ramus and the mental region during the earliest ontogenetic stages and again at adulthood, is not associated with the development of the teeth. At puberty there is a simultaneous peak in size increase, shape development, and dental maturation likely controlled by the surge of sex hormones with a dimorphic onset age. We argue that the infant and adult dimorphism of the mental region may be associated with the development of supralaryngeal structures.

Oromotor variability in children with mild spastic cerebral palsy: a kinematic study of speech motor control

Background

Treating motor speech dysfunction in children with CP requires an understanding of the mechanism underlying speech motor control. However, there is a lack of literature in quantitative measures of motor control, which may potentially characterize the nature of the speech impairments in these children. This study investigated speech motor control in children with cerebral palsy (CP) using kinematic analysis.

Methods

We collected 10 children with mild spastic CP, aged 4.8 to 7.5 years, and 10 age-matched children with typical development (TD) from rehabilitation department at a tertiary hospital. All children underwent analysis of percentage of consonants correct (PCC) and kinematic analysis of speech tasks: poly-syllable (PS) and mono-syllable (MS) tasks using the Vicon Motion 370 system integrated with a digital camcorder. Kinematic parameters included spatiotemporal indexes (STIs), and average values and coefficients of variation (CVs) of utterance duration, peak oral opening displacement and velocity. An ANOVA was conducted to determine whether PCC and kinematic data significantly differed between groups.

Results

CP group had relatively lower PCCs (80.0-99.0%) than TD group (p = 0.039). CP group had higher STIs in PS speech tasks, but not in MS tasks, than TD group did (p = 0.001). The CVs of utterance duration for MS and PS tasks of children with CP were at least three times as large as those of TD children (p < 0.01). However, average values of utterance duration, peak oral opening displacement and velocity and CVs of other kinematic data for both tasks did not significantly differ between two groups.

Conclusion

High STI values and high variability on utterance durations in children with CP reflect deficits in relative spatial and/or especially temporal control for speech in the CP participants compared to the TD participants. Children with mild spastic CP may have more difficulty in processing increased articulatory demands and resulted in greater oromotor variability than normal children. The kinematic data such as STIs can be used as indices for detection of speech motor control impairments in children with mild CP and assessment of the effectiveness in the treatment.