Comparative tactile sensitivity of the fingertip and apical tongue using complex and pure tactile tasks

Publication date: Available online 5 July 2018Source: Physiology & BehaviorAuthor(s): Brittany L. Miles, Karli Van Simaeys, Morgan Whitecotton, Christopher T. SimonsAbstractBoth the tongue and fingertip are highly tactile tissues relevant in texture perception, but work comparing relative sensitivity to elucidate potential differences in stimulus processing is limited. Presently, the acuity of the tongue and fingertip were compared using a series of tactile acuity tasks. We hypothesized the tongue would show superior acuity regardless of stimuli due to an absent epidermal barrier and its involvement in many high-sensitivity behaviors (e.g. eating, speaking). Acuity was determined using three different tests, two “purely-tactile” just noticeable difference (JND) tasks (punctate pressure and roughness sensitivity) and a more-complex, stereognostic letter-recognition task to evaluate point-and-edge sensitivity. JNDs were determined using the forced-choice staircase method for the punctate deformation force of a monofilament (F;0.0044–0.010 g) and the surface roughness of stainless steel coupons (Ra; 0.177–0.465 μm) in populations of 30 and 31 individuals, respectively. Point-and-edge sensitivity was assessed by determining the letter recognition threshold (RT) based on height (h;1.5–8.0 mm) in an additional 28 individuals using a modified staircase method. While subjects had significantly lower JNDs with their tongues for both “purely-tactile” tasks (punctat...

Source: Physiology and Behavior - July 10, 2018 Category: Physiology Source Type: research