Date of Award

Summer 2015

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Department of Communication Sciences and Disorders

Advisor(s)

Christy Ludlow

Cynthia O'Donoghue

Abstract

This study investigated the effects of taste on swallowing frequency and cortical activation in the swallowing network. The effects of salivary flow and taster status were also examined, along with genetic taster status. The effects of a 3ml bolus compared sour, sour with slow infusion, sweet, water, and water with infusion. Swallowing frequency was significantly higher 0-15 seconds after bolus delivery than 16-30 seconds. Swallowing frequency was higher in the sour conditions, whereas sweet and water did not differ. Functional near-infrared spectroscopy recordings measured changes in blood oxygenation (HbO) in the right and left hemispheres in the premotor, S1 and supplementary motor area in response to swallowing a bolus indicated a significant interaction of side and channel. Event-related analyses of HbO following bolus administration of taste solutions were significantly higher in the sensory than the premotor area in the right hemisphere. A block average analysis of the response to taste between 17 and 22 seconds after bolus administration revealed significant differences between hemispheres and regions. Genetic taster status was not significant in any of the analyses. The highest activation in response to sour taste was in the premotor regions of both hemispheres. The results indicated that sour taste effectively increased swallowing frequency and cortical activation while increasing salivary flow in comparison to water and sweet taste. In conclusion, sour taste may have peripheral effects on salivary flow while up-regulating the activation of the swallowing network at the cortical level.

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