Biomedical subjects

Susan Shaiman

Publications and source records attributed to Susan Shaiman.

3 recordsLinked to original sources

PubMed2003

Lung volume effects on pharyngeal swallowing physiology.

The experiment was a prospective, repeated-measures design intended to determine how the variation of lung volume affects specific measures of swallowing physiology. Swallows were recorded in 28 healthy subjects, who ranged in age from 21 to 40 yr (mean age of 29 yr), by using simultaneous videofluoroscopy, bipolar intramuscular electromyography, and respiratory inductance plethysmography. Each subject swallowed three standardized pudding-like consistency boluses at three randomized lung volumes: total lung capacity, functional residual capacity, and residual volume. The results showed that pharyngeal activity duration of deglutition for swallows produced at residual volume was significantly longer than those occurring at total lung capacity or at functional residual capacity. No significant differences were found for bolus transit time or intramuscular electromyography of the superior constrictor. The results of this experiment lend support to the hypothesis that the respiratory system may have a regulatory function related to swallowing and that positive subglottic air pressure may be important for swallowing integrity. Eventually, new treatment paradigms for oropharyngeal dysphagia that are based on respiratory physiology may be developed.

Adult↗

PubMed2002

Task-specific sensorimotor interactions in speech production.

Speaking involves the activity of multiple muscles moving many parts (articulators) of the vocal tract. In previous studies, it has been shown that mechanical perturbation delivered to one moving speech articulator, such as the lower lip or jaw, results in compensatory responses in the perturbed and other non-perturbed articulators, but not in articulators that are uninvolved in the specific speech sound being produced. These observations suggest that the speech motor control system may be organized in a task-specific manner. However, previous studies have not used the appropriate controls to address the mechanism by which this task-specific organization is achieved. A lack of response in a non-perturbed articulator may simply reflect the fact that the muscles examined were not active. Alternatively, there may be a specific gating of somatic sensory signals due to task requirements. The present study was designed to address the nature of the underlying sensorimotor organization. Unanticipated mechanical loads were applied to the upper lip during the "p" in "apa" and "f" in "afa" in six subjects. Both lips are used to produce "p", while only the lower lip is used for "f". For "apa", both upper lip and lower lip responses were observed following upper lip perturbation. For "afa", no upper lip or lower lip responses were observed following the upper lip perturbation. The differential response of the lower lip, which was phasically active during both speech tasks, indicates that the neural organization of these two speech tasks differs not only in terms of the different muscles used to produce the different movements, but also in terms of the sensorimotor interactions within and across the two lips.

Adolescent↗

PubMed2002

Articulatory control of vowel length for contiguous jaw cycles: the effects of speaking rate and phonetic context.

The current study examined contiguous cycles of jaw movement in order to determine if select suprasegmental manipulations operate globally across the entire utterance, while phonetic changes are more locally administered. Specifically, articulatory kinematics were examined to determine if intra- and inter-articulatory spatial and temporal organization across manipulations of speaking rate was maintained for both jaw cycles while differing between the two cycles for phonetic changes (i.e., in coda composition) specific to the second jaw cycle. Five normal speakers repeated the syllables /paep/, /paeps/, and /paepst/, embedded in the carrier phrase, "Now say again," using slow, normal, and fast speaking rates. Measures were made of the magnitude of jaw opening peak velocity and time to peak velocity, as well as of coarticulatory overlap and interarticulator timing, for the first jaw cycle (jaw lowering for /eI/ in "say" to the first /p/) and the second jaw cycle (jaw lowering for /ae/ to the second /p/). The current data indicate that, for intra-articulatory kinematics, the manipulation of phonetic context resulted in localized adjustments, whereas the manipulation of speaking rate was applied globally across the utterance. Conversely, for inter-articulatory kinematics, the upper lip-jaw synergy was reconfigured across the utterance for manipulations of speaking rate, whereas this synergy was maintained for localized manipulations in phonetic context. Results are discussed with respect to motor strategies being flexibly implemented as a result of contextual variation and speech rate.

Adult↗