Effects of a pressure surround on the regional taste detection threshold for sodium chloride

The question as to whether tactile stimulation alters proximal taste function in humans has never been answered, despite the suggestion of anatomical and physiological associations between somatosensory and gustatory function in a number of species. In this study, we established NaCl detection thresholds for a 25 mm2 anterior tongue region on four test occasions in each of 12 men and 12 women. Testing was performed using the Regional Automated Taste Testing System (RATTS), a device that allows for accurate temporal and spatial presentation of tastants to the lingual surface. On each test occasion, a different negative pressure (vacuum suction) was applied around the stimulus presentation field of the glass stimulation device (i.e. 40, 50, 60 and 70 mmHg). The order of presentation of the vacua was systematically counterbalanced among subjects across sessions using 4 x 4 Latin square sequences. Neither the vacua nor their order of presentation meaningfully altered the taste threshold values, even though the higher vacua produced persistent discernible discomfort in most subjects. On average, taste thresholds tended to be marginally lower in women than in men. These data indicate that static vacuum-induced tactile stimulation around a discrete anterior taste field has no meaningful influence on NaCl detection threshold sensitivity.