Sensory function during the oral processing of liquids is thought to play a key role in informing the tailoring of swallowing motor behaviours to the flow characteristics of the bolus. In addition to taste receptors, the mouth and tongue house trigeminal nerve receptors that support the sensory detection of bolus size, shape (stereognosis), mass, temperature and movement. Recent studies suggest that healthy adults lose tongue strength with advancing age. However, little is known about changes in the sensory function of the tongue attributable to age, or associated with reductions in strength. In this study, we explored lingual tactile acuity in healthy young and older adults, and measured the relationship between tactile acuity and measures of tongue strength. The results showed an age-related reduction in lingual tactile acuity that was not explained by variations in tongue strength.
Practical applications: Sensory motor interactions are a topic of interest in understanding the processing activities that take place in the mouth during eating and swallowing. In this paper, we explore a test of sensory acuity in the mouth, in which the tongue is used to "read" embossed letters on Teflon strips. Our questions were to determine whether sensory acuity for this task declines with age, or with age-related reductions in tongue strength. We determined that older people perform this task with less accuracy, suggesting some changes in oral sensory function with age. However, these changes were not related to tongue strength. The findings suggest that strength does not play a major role in the kind of sensory discrimination task tested in this study.
Keywords: Oral sensation; pressure; spatial resolution acuity; stereognosis; tongue.