The effect of cooling on the vibrotactile sensitivity of the tongue

Abstract

Two experiments were carried out to investigate the effect of cooling on the sensitivity of the tongue to vibration. In the first experiment the temperature of the tongue was held at 36 0 , 28 0 , or 20 0 C while the thresholds for detecting 30-and 250-Hz vibrations were measured using a twoalternative forced-choice paradigm. Cooling the tongue to 20 0 reduced the sensitivity to 250-Hz vibration but did not disturb the sensitivity to 30-Hz vibration. The second experiment established that cooling continued to reduce the sensitivity to the 250-Hz stimulus even when intensity levels were raised to 30 dB SL. The results are discussed in relation to (1) which types of mechanoreceptors mediate the perception of vibration on the dorsal surface of the tongue, (2) the effect of a rigid surround on lingual vibrotactile sensitivity, and (3)the possible impact of temperature on perception of the mechanical characteristics of foods.Tactile information from the tongue is important for both the manipulation and the sensory assessment of ingested foods. In recognition of this fact and because of the presumed importance of tactile feedback from the tongue during speech production, a relatively large literature has developed on lingual mechanical sensitivity.

Influences of Thermal and Gustatory Characteristics on Sensory and Motor Aspects of Swallowing

“…2). Previous psychophysical reports may be related to the present finding: (1) the tongue (at least its tip) is highly sensitive to both warmth and cold [21], and (2) the oral cavity as a whole perceives warming more readily than cooling [22]. The first report [21] suggests that the tongue is the initial sensor responsible for the change in the subjective difficulty of swallowing (Fig.…”

Effect of tongue temperature on oral tactile sensitivity and viscosity discrimination

“…Fucci et al (1976) found an increased vibrotactile threshold when cooling and warming the tongue and suggested that the point of average body temperature (37 o C) was concomitant with minimal lingual vibrotactile thresholds. Green (1987) also reported a significant loss of vibrotactile sensitivity when the tongue was exposed to cold stimulation. However, previous researchers generally agreed with the absence of the Pacinian corpuscles in the dorsal surface of the tongue (Gairns, 1953;Verrillo, 1966).…”

“…Why is there a similar relation between surface temperature and vibratory perception thresholds either on the skin or on the tongue surface? One interesting feature of vibratory perception is that the threshold is not solely determined by the presence or absence of Pacinian corpuscles s in the dorsal surface of the tongue but also contributed to other mechanoreceptor systems (Green, 1987). Although few studies have documented the histological structure of the tongue, Green (1987) suggested as that other mechanoreceptors sensitive to lower vibratory frequency, deep-lying Pacinian corpuscles, are located at tongue tissues (nerve bundles and blood vessels) and underside of the tongue work together to mediate detection of vibration.…”