Submental Surface Electromyography Research Articles

Comparison of Submental Surface Electromyography during Dry Swallow between Irradiated Head and Neck Cancer Survivors and Normal Individuals.

This study compared the submental surface electromyography (sEMG) duration and amplitude during dry swallowing between irradiated head and neck cancer (HNC) survivors and age-matched normal individuals. Further, the relationship between submental and infrahyoid sEMG in the irradiated HNC group was explored. Forty participants (20 HNC survivors and 20 age-matched normal individuals) participated in this study. The HNC survivors had completed organ preservation cancer treatment (at least 1-month post-treatment). They were on a complete oral diet without enteral supplementation (FOIS score> 4). Submental and infrahyoid sEMG activity was calculated for three trials of saliva swallow for each participant using sEMG. The duration and amplitude parameters considered were: onset duration - duration from the onset of swallowing to the maximum amplitude, offset duration - duration from the maximum amplitude to the end of the swallowing activity, total duration, and maximum amplitude. The study found that irradiated HNC survivors exhibited prolonged temporal measures, particularly in the offset duration, which suggested a delayed descent of the hyolaryngeal complex during swallowing. Additionally, the HNC group showed a positive correlation between submental and infrahyoid sEMG. Furthermore, it was observed that the rate of increase in the duration of submental sEMG during subsequent swallowing was greater in HNC survivors which could be due to reduced salivation. Compared to age-matched normal individuals, irradiated HNC survivors manifest alterations in the submental muscle activities during dry swallowing as measured using sEMG. The temporal and amplitude changes are likely to have arisen as a consequence of postradiation changes.

Evaluating Anterior and Posterior Oral Tongue Contributions to Pressure Generation: A Comparison Between Regular and Effortful Saliva Swallows.

This study determined the contributions of the anterior and posterior tongue regions in tongue pressure generation during regular saliva swallows (SSs) and effortful swallows (ESs) completed under two different instructions. The association between tongue pressure and perceived effort to swallow was also examined. Forty healthy adults without swallowing disorders participated in this study, divided into two age groups: 20 younger (Mage = 21.95 years, SD = 4.43) and 20 older (Mage = 70.10 years, SD = 4.30). Simultaneous data acquisition involved submental surface electromyography, tongue manometry, and a visual analog scale across swallowing conditions (SS, ES with tongue emphasis, and ES with pharyngeal squeezing). The main outcome measures were tongue pressure during swallowing and perceived effort to swallow. Overall tongue pressure during ESs with tongue emphasis and with pharyngeal squeezing was greater than that during SSs (R2 = .78, p < .001). Moreover, tongue pressure during the ES with tongue emphasis was greater than that during the ES with pharyngeal squeezing (t = 25.63, p < .001). The posterior tongue region generated more pressure during SSs (R2 = .64, p < .001) and the ES with tongue emphasis (R2 = .55, p < .001) than the anterior tongue. Finally, a positive correlation was found between perceived effort and tongue pressure during swallowing (r = .75, 95% CI [0.72, 0.77]). Tongue pressure generation was affected by the type of instruction used to elicit ESs, and the posterior tongue showed relatively greater pressure contributions than the anterior tongue for ESs with tongue emphasis and SSs. Furthermore, age-related declines in pressure generation during swallowing were not evidenced in this study, underscoring the ability of healthy older individuals to appropriately modulate lingual pressure during ESs. Last, our results showed that the visual analog scale is a simple tool for rating swallowing effort during ESs, supporting its potential clinical use to train ESs.

Wearable Submental sEMG Sensors for the Treatment of Dysphagia; A Pilot Study

Swallowing is a complex physiological process that is essential for survival and quality of life. When disrupted, it leads to oropharyngeal dysphagia. This is a common affliction which can have massive implications on health, including an increased risk for pneumonia and malnutrition.&#x0D; Rehabilitative therapy is effective in improving swallowing function, but usually requires clinic visits with a speech language pathologist weekly or multiple times per week. Making treatment more accessible could improve follow-through among the disadvantaged patients with the greatest need for therapy.&#x0D; To address this need, the Purdue I-EaT lab is developing a wearable submental surface electromyography (sEMG) sensor system (i-Phagia) for remote treatment of dysphagia. To evaluate the feasibility of using this device for a single-visit treatment, a pilot pre-post study is being conducted. Participants are evaluated with videofluoroscopic swallowing studies (VFSS) and sEMG before and after a 45-minute treatment session, involving two rehabilitative swallowing exercises, using i-Phagia. Following the post-treatment evaluation, feedback is collected regarding the tolerability of the sensor, including presence of any skin irritation. Outcome variables include normalized mean amplitude, time to peak amplitude of the sEMG signal, and patient satisfaction and safety.&#x0D; As of now, five participants (ages 21, 21, 71, 69, 80) have participated. sEMG analysis was completed in four participants due to data loss for one. Pre-post sEMG analysis of neuromuscular activity showed an increase in normalized amplitude post-treatment in three of four analyzed participants. Four of five participants reported high satisfaction (average score 88/100) and one moderate, and all reported no pain (Wong-Baker pain scale).&#x0D; These results show the feasibility and preliminary effectiveness of using the i-Phagia for in-clinic treatment visits in a small sample of healthy participants. Further research is ongoing to examine the feasibility for use in patients with Parkinson’s disease and for remote use outside of clinic.

Hyolaryngeal Movement During Normal and Effortful Swallows Determined During Ultrasonography.

This study investigated (a) the effects of the effortful swallow under two different instructions (tongue emphasis vs. pharyngeal squeezing) on hyoid displacement and hyoid-larynx approximation, (b) the association between tongue pressure and hyolaryngeal movement during normal swallowing and the effortful swallow produced with tongue emphasis, and (c) age-related differences in hyolaryngeal movement during normal and effortful swallows (tongue emphasis vs. pharyngeal squeezing) in healthy individuals. Forty healthy adults (20 younger and 20 older) swallowed their saliva as they normally do (normal swallow) and performed the effortful swallow with tongue emphasis and pharyngeal squeezing. Tongue-to-palate pressure during swallowing was measured using the Iowa Oral Performance Instrument, hyolaryngeal movement was measured using ultrasonography, and submental surface electromyography was used to track swallows. Results revealed differences in hyolaryngeal movement across swallowing types. Both types of effortful swallows showed greater hyolaryngeal movement than normal swallows. Additionally, hyolaryngeal movement was greater during the effortful swallow with tongue emphasis than the effortful swallow with pharyngeal squeezing. Age-related differences were found only in hyoid-larynx approximation during the effortful swallow with tongue emphasis (younger > older adults). Furthermore, moderate positive correlations were identified between tongue pressure and hyolaryngeal movement during normal swallows and the effortful swallow with tongue emphasis. The findings show that varying instructions of the effortful swallow affect hyolaryngeal movement differently, suggesting that clinicians may need to individualize the effortful swallow instruction according to the physiological impairments of each patient. Additionally, natural age-related changes in swallowing physiology do not seem to affect an individual's ability to perform the effortful swallow or to impact hyolaryngeal movement. Finally, the association between tongue pressure and hyolaryngeal movement during normal swallows and the effortful swallow with tongue emphasis suggests that the tongue plays a critical role in swallowing, priming subsequent swallowing events.

Effects of Age and Lingual-Palatal Pressure Levels on Submental Surface Electromyography Measures.

Submental surface electromyography (sEMG) may provide information about the lingual-palatal pressure (LPP) during swallowing. However, the extent to which changes in age and LPP levels are reflected in different sEMG measures is unclear. This study aimed to understand the effects of age and different levels of submaximal LPPs on submental sEMG peak, average, and integrated values in healthy adults. Ninety community-dwelling healthy participants were categorized into three age groups (young: 20-39years, middle age: 40-59years, older: 60 ≥ years). sEMG and LPP measurements were collected concurrently. After placing the sEMG electrodes, the maximal isometric LPP was established using the Iowa oral performance instrument (IOPI) on the anterior tongue. sEMG recordings were conducted for three submaximal LPP levels, including 40%, 60%, and 80% of the maximum LPP. Two-way repeated measure ANOVAs were conducted to find the effects of age and varying LPP levels on mean sEMG peak, average, and integrated measures. A significant age by LPP level interaction was identified for sEMG peak [F (4, 172) = 4.116, p < 0.007, ηp2 = 0.087], sEMG average [F (4, 170) = 5.049, p < 0.001, ηp2 = 0.106], and sEMG integrated values [F (4, 170) = 4.179, p < 0.003, ηp2 = 0.090]. Post hoc testing demonstrated that, in general, sEMG values significantly increased with rising LPP levels, primarily for younger and middle-aged adults. Furthermore, at 80% of maximum LPP, older adults generated less sEMG average and integrated values than middle age (only significant for sEMG integrated value) and younger adults. Likewise, max LPP was lower in older adults compared with young and middle-aged groups. Submental sEMG has the potential to be incorporated into a skill-based lingual exercise paradigm to improve tongue function during swallowing. Moreover, submental sEMG can characterize some age-related subclinical changes in swallowing.

Kinematic Visual Biofeedback Improves Accuracy of Swallowing Maneuver Training and Accuracy of Clinician Cues During Training in Stroke Patients with Dysphagia.

Dysphagia (swallowing impairment) is a common and often life-threatening problem after stroke. Submental surface electromyography (ssEMG) visual biofeedback is a commonly used clinical tool to train novel swallowing maneuvers, even though its effectiveness has been questioned. To compare the effect of ssEMG and videofluoroscopy (VF) visual biofeedback on swallowing airway protection accuracy when training the volitional laryngeal closure swallowing maneuver (vLVC) in poststroke patients with dysphagia. Researchers also examined whether clinicians accurately judged vLVC performance. The hypothesis was that patient vLVC accuracy and clinician verbal cue accuracy will be greatest with VF (kinematic) visual biofeedback. Nineteen patients with dysphagia post stroke. Outpatient swallowing research laboratory. Randomized clinical trial. Patients underwent 2 study phases. Phase 1: first demonstrated ability to perform the vLVC accurately. Phase 2: vLVC training. Participants were randomized into three biofeedback groups including the ssEMG group (ssEMG biofeedback in both phases), the VF group (VF biofeedback in both phases), and the mixed group (VF phase 1, ssEMG phase 2). To promote the best vLVC performance, a clinician provided real-time, verbal cueing using only the visual biofeedback type also seen by the patient, although both VF and ssEMG were recorded for all participants. Patient performance accuracy and clinician feedback accuracy for performing the vLVC maneuver. Both accuracy of vLVC training performance and clinician feedback accuracy were worse in the ssEMG group compared with the VF and mixed groups (P < .001). Swallowing airway protection requires precisely timed movements of small, hidden laryngeal and pharyngeal structures. Kinematic biofeedback (VF) may be required, at some point, to ensure that target swallowing movements are being trained during rehabilitation, rather than maladaptive movements. I.

Abstract TP150: Kinematic Visual Biofeedback is Best When Training Novel Swallowing Behaviors in Dysphagic Patients After Stroke

Introduction: Dysphagia (swallowing impairment) is a common and often life threatening problem after stroke. Submental surface electromyography (ssEMG) visual feedback is a commonly used clinical tool to train novel swallowing maneuvers, even though its effectiveness has been questioned in studies of healthy adults. This study compares the effect of ssEMG and videofluoroscopy (VF) visual biofeedback on hyo-laryngeal accuracy when training the volitional laryngeal closure swallowing maneuver (vLVC) in post-stroke patients with dysphagia. The vLVC maneuver involves swallowing first, then maintaining laryngeal vestibule closure for at least 2 seconds. This study also examines the accuracy of clinician judgements about patient vLVC performance. Hypothesis: Accuracy will be reduced when only ssEMG (non-kinematic) versus VF (kinematic) visual feedback is used to teach the vLVC. Methods: Stroke participants (N=14) underwent 2 study phases. Phase 1: first demonstrated ability to perform the vLVC accurately. Phase 2 was vLVC training. Participants were randomized into three biofeedback groups including the ssEMG Group (ssEMG biofeedback in phases 1 and 2), the VF Group (VF biofeedback in phases 1 and 2), and the Mixed Group (VF phase 1, ssEMG phase 2). A clinician provided real-time, verbal cueing utilizing the assigned visual biofeedback to promote vLVC accuracy. The clinician could only see the assigned type of feedback also seen by the patient, although both VF and ssEMG were recorded for all participants. Results: Both accuracy of vLVC training performance and clinician feedback were worst in the ssEMG group compared to the VF and Mixed Groups (linear mixed models p&lt;0.001). Conclusions: Swallowing airway protection requires precisely timed movements of small, hidden laryngeal and pharyngeal structures. Kinematic feedback may be required to ensure that target swallowing movements are being trained in rehabilitation.

Tongue Pressure Production and Submental Surface Electromyogram Activities During Tongue-Hold Swallow with Different Holding Positions and Tongue Length.

Our previous study regarding the tongue-hold swallow (THS) demonstrated that the tongue-to-palate contact during THS could be influenced by the maximum tongue protrusion length (MTPL) of individual subjects, resulting in two different patterns of pressure generation. The present study further analyzed the influence of MTPL on the tongue pressure production along with submental surface electromyography (sEMG) during THS, in order to establish an index to better control THS effects. Tongue pressure using a sensor sheet system and concurrent submental sEMG activities were measured during swallowing tasks in 18 healthy young adults. Task conditions comprised THS at two different degrees of tongue protrusion and dry swallow. Tongue pressures and sEMG activities were compared among three task conditions, and correlations of MTPL with tongue pressure were also investigated. Additionally, a ROC curve was used to find a cut-off value for MTPL to predict changes (increases and decreases) in tongue pressure during THS. The duration and the amount of submental muscle activity increased concurrently during THS. Two trends were shown on the change in tongue pressure at the posterior-circumferential part of the hard palate during THS compared to dry swallow; the maximal magnitude and the integrated value of tongue pressure increased in some subjects, while these values decreased in others. Thirty-two millimeters was found to be the cut-off value of MTPL, which distinguishes increase/decrease pattern of tongue pressure with sensitivities of 60.0-85.7%. The present finding suggests that more reliable THS effects should be attainable using MTPL to set the tongue-hold position.

Kinematic Visual Biofeedback Improves Accuracy of Learning a Swallowing Maneuver and Accuracy of Clinician Cues During Training.

Submental surface electromyography (ssEMG) visual biofeedback is widely used to train swallowing maneuvers. This study compares the effect of ssEMG and videofluoroscopy (VF) visual biofeedback on hyo-laryngeal accuracy when training a swallowing maneuver. Furthermore, it examines the clinician's ability to provide accurate verbal cues during swallowing maneuver training. Thirty healthy adults performed the volitional laryngeal vestibule closure maneuver (vLVC), which involves swallowing and sustaining closure of the laryngeal vestibule for 2s. The study included two stages: (1) first accurate demonstration of the vLVC maneuver, followed by (2) training-20 vLVC training swallows. Participants were randomized into three groups: (a) ssEMG biofeedback only, (b) VF biofeedback only, and (c) mixed biofeedback (VF for the first accurate demonstration achieving stage and ssEMG for the training stage). Participants' performances were verbally critiqued or reinforced in real time while both the clinician and participant were observing the assigned visual biofeedback. VF and ssEMG were continuously recorded for all participants. Results show that accuracy of both vLVC performance and clinician cues was greater with VF biofeedback than with either ssEMG or mixed biofeedback (p<0.001). Using ssEMG for providing real-time biofeedback during training could lead to errors while learning and training a swallowing maneuver.

New method of neck surface electromyography for the evaluation of tongue-lifting activity.

Elevation of the posterior part of the tongue is important for normal deglutition and speech. The purpose of this study was to develop a new surface electromyography (EMG) method to non-invasively and objectively evaluate activity in the muscles that control lifting movement in the posterior tongue. Neck surface EMG (N-EMG) was recorded using differential surface electrodes placed on the neck, 1 cm posterior to the posterior border of the mylohyoid muscle on a line orthogonal to the lower border of the mandible. Experiment 1: Three healthy volunteers (three men, mean age 37·7 years) participated in an evaluation of detection method of the posterior tongue lifting up movement. EMG recordings from the masseter, temporalis and submental muscles and N-EMG revealed that i) N-EMG was not affected by masseter muscle EMG and ii) N-EMG activity was not observed during simple jaw opening and tongue protrusion, revealing the functional difference between submental surface EMG and N-EMG. Experiment 2: Seven healthy volunteers (six men and one woman, mean age 27·9 years) participated in a quantitative evaluation of muscle activity. Tongue-lifting tasks were perfor-med, exerting a prescribed force of 20, 50, 100 and 150 gf with visual feedback. For all subjects, a significant linear relationship was observed bet-ween the tongue-lifting force and N-EMG activity (P < 0·01). These findings indicate that N-EMG can be used to quantify the force of posterior tongue lifting and could be useful to evaluate the effect of tongue rehabilitation in future studies.

Effect of age on human-computer-interface control via neck electromyography.

The purpose of this study was to determine the effect of age on visuomotor tracking using submental and anterior neck surface electromyography (sEMG) to assess feasibility of computer control via neck musculature, which allows people with little remaining motor function to interact with computers. Thirty-two healthy adults participated: 16 younger adults aged 18–29 years and 16 older adults aged 69–85 years. Participants modulated sEMG to achieve targets presented at different amplitudes using real-time visual feedback. Root mean squared (RMS) error was used to quantify tracking performance. RMS error was increased for older adults relative to younger adults. Older adults demonstrated more RMS error than younger adults as a function of increasing target amplitude. The differential effects of age found on static tracking performance in anterior neck musculature suggest more difficult translation of human–computer interfaces controlled using anterior neck musculature for static tasks to older populations.

Barium Versus Nonbarium Stimuli: Differences in Taste Intensity, Chemesthesis, and Swallowing Behavior in Healthy Adult Women

The authors examined the impact of barium on the perceived taste intensity of 7 different liquid tastant stimuli and the modulatory effect that these differences in perceived taste intensity have on swallowing behaviors. Participants were 80 healthy women, stratified by age group (<40; >60) and genetic taste status (supertasters; nontasters). Perceived taste intensity and chemesthetic properties (fizziness; burning-stinging) were rated for 7 tastant solutions (each prepared with and without barium) using the general Labeled Magnitude Scale. Tongue-palate pressures and submental surface electromyography (sEMG) were simultaneously measured during swallowing of these same randomized liquids. Path analysis differentiated the effects of stimulus, genetic taste status, age, barium condition, taste intensity, and an effortful saliva swallow strength covariate on swallowing. Barium stimuli were rated as having reduced taste intensity compared with nonbarium stimuli. Barium also dampened fizziness but did not influence burning-stinging sensation. The amplitudes of tongue-palate pressure or submental sEMG did not differ when swallowing barium versus nonbarium stimuli. Despite impacting taste intensity, the addition of barium to liquid stimuli does not appear to alter behavioral parameters of swallowing. Barium solutions can be considered to elicit behaviors that are similar to those used with nonbarium liquids outside the assessment situation.

Influence of the Perceived Taste Intensity of Chemesthetic Stimuli on Swallowing Parameters Given Age and Genetic Taste Differences in Healthy Adult Women

This study examined whether the perceived taste intensity of liquids with chemesthetic properties influenced lingua-palatal pressures and submental surface electromyography (sEMG) in swallowing, compared with water. Swallowing was studied in 80 healthy women, stratified by age group and genetic taste status. General Labeled Magnitude Scale ratings of taste intensity were collected for deionized water; carbonated water; 2.7% w/v citric acid; and diluted ethanol. These stimuli were swallowed, with measurement of tongue-palate pressures and submental sEMG. Path analysis differentiated stimulus, genetic taste status, age, and perceived taste intensity effects on swallowing. Signal amplitude during effortful saliva swallowing served as a covariate representing participant strength. Significant differences (p < .05) in taste intensity were seen across liquids: citric acid > ethanol > carbonated water > water. Supertasters perceived greater taste intensity than did nontasters. Lingua-palatal pressure and sEMG amplitudes were correlated with the strength covariate. Anterior palate pressures and sEMG amplitudes were significantly higher for the citric acid stimulus. Perceived taste intensity was a significant mediator of stimulus differences. These data provide confirmatory evidence that high-intensity sour stimuli do influence swallowing behaviors. In addition, taste genetics influence the perception of taste intensity for stimuli with chemesthetic properties, which modulates behavioral responses.

Negative pressure and muscle activity during discrete sips from high resistance straws

The purpose of the current investigation was to explore how intra-oral negative pressure and submental muscle activity vary across sips from straws varying in internal diameter and across conditions of low versus high effort. Healthy adults took discrete sips from four straws varying in internal diameter. Sips were performed under normal and high effort conditions. Submental surface electromyography (sEMG) and negative intra-oral pressure were recorded during sips. Significant main effects of straw condition were observed for negative intra-oral pressure. A non-significant trend for increased muscle activity associated with smaller straw diameter was also observed. Significant main effects of effort condition were observed for both submental sEMG and negative intra-oral pressure. The findings are interpreted as supporting the clinical hypothesis that high resistance drinking straws varying in diameter may offer systematic overload to the oral musculature. The findings also support encouraging maximum effort to achieve even further overload.

Tongue Pressure and Submental Surface Electromyography Measures During Noneffortful and Effortful Saliva Swallows in Healthy Women

The effortful swallow, a compensatory technique frequently employed by speech-language pathologists for their patients with dysphagia, is still not fully understood in terms of how it modifies the swallow. In particular, although age-related changes are known to reduce maximum isometric tongue pressure, it is not known whether age affects people's ability to perform the effortful swallow. In this study, differences were explored between younger and older healthy women in execution of the effortful swallowing maneuver through a comparative analysis of effortful and noneffortful swallows. Eighty healthy women (40 age 18-35 years and 40 age 60 and older) participated. Peak amplitude measures and the timing of signal onset to peak were measured using concurrent tongue pressure and submental surface electromyography. Result Statistically significant main effects of age group were not observed in the amplitude data, but older participants showed slower rise times to peak anterior tongue-palate pressure. Despite the general age-related deterioration of the swallowing musculature due to the phenomenon of sarcopenia, older women can still produce noneffortful and effortful swallows with lingual pressure and submental surface electromyography amplitudes similar to younger women.

The Development of Swallowing Respiratory Coordination

Abstract Research exists that evaluates the mechanics of swallowing respiratory coordination in healthy children and adults as well and individuals with swallowing impairment. The research program summarized in this article represents a systematic examination of swallowing respiratory coordination across the lifespan as a means of behaviorally investigating mechanisms of cortical modulation. Using time-locked recordings of submental surface electromyography, nasal airflow, and thyroid acoustics, three conditions of swallowing were evaluated in 20 adults in a single session and 10 infants in 10 sessions across the first year of life. The three swallowing conditions were selected to represent a continuum of volitional through nonvolitional swallowing control on the basis of a decreasing level of cortical activation. Our primary finding is that, across the lifespan, brainstem control strongly dictates the duration of swallowing apnea and is heavily involved in organizing the integration of swallowing and respiration, even in very early infancy. However, there is evidence that cortical modulation increases across the first 12 months of life to approximate more adult-like patterns of behavior. This modulation influences primarily conditions of volitional swallowing; sleep and naïve swallows appear to not be easily adapted by cortical regulation. Thus, it is attention, not arousal that engages cortical mechanisms.

Effects of Taste Solutions, Carbonation, and Cold Stimulus on the Power Frequency Content of Swallowing Submental Surface Electromyography

This study explored the effects of 5 taste solutions (citric acid, sucrose, sodium chloride, caffeine, and sodium glutamate) versus water on the power frequency content of swallowing submental surface electromyography (sEMG). Healthy subjects were presented with 5 ml of each of 5 tastants and water. Data were collected in 3 trials of the 5 tastants and water by using submental sEMG, which was then subjected to spectral analysis. Sour and salt taste solutions increased the spectrum-integrated values of the total power components. The spectrum-integrated values of low-frequency power (below 10 Hz) in the salt taste trial significantly increased, whereas those of high-frequency power (above 10 Hz) in the sour taste trial tended to increase. Neither pleasantness nor intensity of taste was related to these changes. This study also explored the effects of carbonation and cold stimulus on the power frequency content of continuous swallowing sEMG for 60-ml solutions. Carbonation significantly increased the spectrum-integrated value of the total power components by significantly increasing the high-frequency content. Cold stimulus significantly decreased the low-frequency content. In summary, this study reveals that taste, carbonation, and cold stimulus have qualitatively different influences on the power frequency content of swallowing sEMG.

The influence of volition on breathing-swallowing coordination in healthy adults.

This research was designed to clarify the role of cortical modulation in the coordination of respiration and swallowing. Time-locked recordings of submental surface electromyography, nasal airflow, and thyroid acoustics were used to evaluate nonnutritive breathing-swallowing coordination (BSC) and swallowing apnea duration (SAD) of 20 healthy adults during 3 conditions. These conditions represented a continuum of volitional through nonvolitional swallowing control on the basis of a decreasing level of cortical activation: voluntarily initiated swallows during wakefulness, nonvolitional awake swallows, and reflexively initiated swallows during sleep. Differing proportions of swallows at the cusps between inspiration and expiration were found between the volitional and nonvolitional conditions, irrespective of the level of arousal. SAD was unaltered by condition. In conclusion, BSC is influenced by degree of volition but not by level of arousal. This implies that cortical influence on BSC is limited to conditions in which swallowing is voluntarily initiated and indirectly implicates the recruitment of the supplementary motor or insular cortices. SAD remained stable across conditions and may therefore be considered relatively impervious to suprabulbar influence.

The Influence of Taste on Swallowing Apnea, Oral Preparation Time, and Duration and Amplitude of Submental Muscle Contraction

Prior research has documented a modulating effect of taste on swallowing. We hypothesized that presentation of tastant stimuli would be a significant variable in swallowing-respiratory coordination, duration of oral bolus preparation, and submental muscle contraction. Twenty-three healthy females were presented with 1-cm(3) gelatin samples flavored with 4 tastants of increasing intensities. Visual analogue scale ratings of perceived intensity of each were used to identify relative equivalent concentrations across the 4 tastants. Data were then collected during ingestion of 5 trials of the 4 equivalent tastants using measurements of nasal airflow and submental surface electromyography (sEMG) to record biomechanical measures. Chi-square analysis failed to identify a statistically significant influence of taste on the phase location of swallowing apnea. Repeated measures analysis of variance demonstrated significant taste effects for oral preparation time, submental sEMG amplitude, and duration (P < 0.02). Sweet tastants were prepared for a shorter time when compared with bitter tastants. Swallow duration for sour, salty, and bitter tastants were longer than sweet and neutral tastants. Sour tastants resulted in the greatest amplitude of submental muscle contraction during swallowing. This study supports existing research that found that sour substances were swallowed with more effort when compared with other tastes.

The Influence of Orolingual Pressure on the Timing of Pharyngeal Pressure Events

This study explored the influence of two methods of effortful swallow execution on the timing of pharyngeal pressure events. Participants were asked to either emphasize or minimize tongue-to-palate contact during performance of the maneuver. Twenty healthy participants were evaluated using concurrent submental surface electromyography (sEMG), orolingual manometry, and pharyngeal manometry. Each subject performed three repetitions of three counterbalanced tasks (noneffortful dry swallows, effortful dry swallows with tongue-to-palate emphasis, and effortful dry swallows with tongue-to-palate de-emphasis). Four variables were measured: Onset Lag vs. sEMG Peak, Peak Lag vs. sEMG Peak, Total Duration, and Percent Rise Time to Peak. Compared to noneffortful swallows, the effortful swallow task elicited significantly earlier onsets and peaks of pharyngeal pressures relative to the submental sEMG peak. Total pressure event durations were greater and rise times were significantly shorter. When comparing the two methods of effortful swallow execution, a longer latency to peak proximal pharyngeal pressure was found in the tongue-to-palate emphasis condition. These results support the interpretation that the effortful swallow maneuver involves generation of higher velocity bolus driving forces that propel the bolus into and through the pharynx with greater efficiency and that pressure is then sustained to facilitate more complete bolus clearance.