Mechanical frequency detection thresholds in the human face.

Afferent information originating from mechanoreceptors located within perioral facial skin is considered to play an important role in the development and maintenance of fine motor skill associated with the production of speech. To date, little quantitative information is available on the frequency sensitivity of the face to controlled sinusoidal displacements, especially in areas of tissue that change shape during speech. The purpose was to determine the mechanical frequency detection thresholds of select skin sites in the face and hand using a psychophysical procedure. Mean frequency detection thresholds for all facial skin sites were significantly higher than thresholds for the forefinger. Further, pacinian-type frequency sensitivity, characteristic of the finger, was absent in the face. Finally, vibratory stimuli may be useful in the assessment of skin sense in patients with suspected involvement of the trigeminal system. A case study is presented to highlight the quantitative nature of this psychophysical procedure.