Faculty Bibliography

PURPOSE: Evidence of tongue-palate pressure modulation during swallowing between thin and nectar-thick liquids stimuli has been equivocal. This mirrors a lack of clear evidence in the literature of tongue and hyoid movement modulation between nectar-thick and thin liquid swallows. In the current investigation, the authors sought to confirm whether tongue-palate pressures are modulated between discrete swallows of water and nectar-thick juice. METHOD: Tongue-palate pressures were measured at 3 sites (anterior, medial, and posterior palate) using an adhered 3-bulb pressure strip in 20 healthy, young adults during discrete swallows of water and nectar-thick apple juice. RESULTS: Pressure modulation was not noted with respect to pressure amplitudes (in mm Hg), but was identified both in the pressure patterns observed (the sites and number of bulbs activated) and temporal aspects of pressure duration. CONCLUSION: Tongue-palate pressure amplitude modulation does not occur for nectar-thick swallows compared to thin liquid swallows. Modulation does, however, occur with respect to the tongue-palate contact surface area and pressure durations. The authors introduce the concept of pressure slope as a meaningful way to examine tongue-palate pressure application in swallowing.

Swallowing accelerometry has been proposed as a potential minimally invasive tool for collecting assessment information about swallowing. The first step toward using sounds and signals for dysphagia detection involves characterizing the healthy swallow. The purpose of this article is to explore systematic variations in swallowing accelerometry signals that can be attributed to demographic factors (such as participant gender and age) and anthropometric factors (such as weight and height). Data from 50 healthy participants (25 women and 25 men), ranging in age from 18 to 80 years and with approximately equal distribution across four age groups (18-35, 36-50, 51-65, 66 and older) were analyzed. Anthropometric and demographic variables of interest included participant age, gender, weight, height, body fat percent, neck circumference, and mandibular length. Dual-axis (superior-inferior and anterior-posterior) swallowing accelerometry signals were obtained for five saliva and five water swallows per participant. Several swallowing signal characteristics were derived for each swallowing task, including variance, amplitude distribution skewness, amplitude distribution kurtosis, signal memory, total signal energy, peak energy scale, and peak amplitude. Canonical correlation analysis was performed between the anthropometric/demographic variables and swallowing signal characteristics. No significant linear relationships were identified for saliva swallows or for superior-inferior axis accelerometry signals on water swallows. In the anterior-posterior axis, signal amplitude distribution kurtosis and signal memory were significantly correlated with age (r = 0.52, P = 0.047). These findings suggest that swallowing accelerometry signals may have task-specific associations with demographic (but not anthropometric) factors. Given the limited sample size, our results should be interpreted with caution and replication studies with larger sample sizes are warranted.

Tongue-pressure resistance training is known to increase tongue strength in seniors and individuals with stroke-related dysphagia. However, evidence of associated functional improvements in swallowing is equivocal. We investigated similarities in pressure waveform profiles between swallowing and several tongue-palate pressure tasks to identify tasks that may be best suited for inclusion in tongue-pressure resistance training protocols for patients who are unable to safely perform real bolus swallows in treatment. Tongue-palate pressures were recorded in 20 healthy young adults. Participants performed water and nectar-thick juice swallows, effortful and noneffortful saliva swallows, and "half-maximum" tongue-palate partial-pressure tasks emphasizing either anterior or posterior tongue-palate contact at different speeds. Pressure slopes (amplitude change over time) during the pressure application (rise) and withdrawal (release) phases were analyzed. A subset of four tasks with the greatest similarity in slope characteristics to those seen in bolus swallows was identified: anterior-emphasis half-maximum tongue-palate presses, posterior-emphasis maximum isometric tongue-palate presses, posterior-emphasis half-maximum slow tongue-palate presses, and effortful saliva swallows. We propose that future research should explore the degree to which swallowing improvements are obtained from treatment protocols that emphasize these tasks.

Dysphagia, or difficulty swallowing, often occurs secondary to conditions such as stroke, head injury or progressive disease, many of which increase in frequency with advancing age. Sarcopenia, the gradual loss of muscle bulk and strength, can place older individuals at greater risk for dysphagia. Data are reported for three older participants in a pilot trial of a tongue-pressure training therapy. During the experimental therapy protocol, participants performed isometric strength exercises for the tongue as well as tongue pressure accuracy tasks. Biofeedback was provided using the Iowa Oral Performance Instrument (IOPI), an instrument that measures tongue pressure. Treatment outcome measures show increased isometric tongue strength, improved tongue pressure generation accuracy, improved bolus control on videofluoroscopy, and improved functional dietary intake by mouth. These preliminary results indicate that, for these three adults with dysphagia, tongue-pressure training was beneficial for improving both instrumental and functional aspects of swallowing. The experimental treatment protocol holds promise as a rehabilitative tool for various dysphagia populations.

This article presents a case study of second dialect acquisition by three children over six years as they shift from Canadian to British English. Informed by Chambers's principles of second dialect acquisition, the analysis focuses on a frequent and socially embedded linguistic feature, T-voicing (e.g., pudding versus putting). An extensive corpus and quantitative methods permit tracking the shift to British English as it is happening. Although all of the children eventually sound local, the acquisition process is complex. Frequency of British variants rises incrementally, lagging behind the acquisition of variable constraints, which are in turn ordered by type. Internal patterns are acquired early, while social correlates lag behind. Acceleration of second dialect variants occurs at well-defined sociocultural milestones, particularly entering the school system. Successful second dialect acquisition is a direct consequence of sustained access to and integration with the local speech community. (Second dialect acquisition, child language variation, T-voicing, mobility)