X-Message-Number: 12233
Date: Mon, 9 Aug 1999 11:35:18 -0700 (PDT)
From: Doug Skrecky <>
Subject: extreme temperature sensitivity of the face

  Stevens JC.  Choo KK.
  John B. Pierce Laboratory and Yale University, New Haven, CT 06519, USA.
  Temperature sensitivity of
  the body surface over the
  life span.
  Somatosensory & Motor Research.  15(1):13-28, 1998.
  Detection thresholds to warming and cooling were measured in 13 regions of
  the body in 60 adults aged between 18 and
  88 years. From these thresholds were constructed maps of
  thermal sensitivity homologous to
  body maps of spatial acuity (in the older
  literature two-point discrimination), long known to the
  somatosensory scientist. Maps of cold and warm sensitivity
  for young, middle-aged and elderly adults, show how
  sensitivity changes with age in the various
  body regions. Three characteristics emerge, irrespective of
  age: (1) sensitivity varies approximately 100-fold over
  the body surface. The
  face, especially near the mouth, is exquisitely sensitive,
  the extremities, by comparison, poor, other
  regions, intermediate. (2) All body regions are more
  sensitive to cold than to warm. (3) The better a region is
  at detecting cold, the better it is at detecting warm. With
  age, thermal sensitivity declines.
  The greatest changes take place in the
  extremities, especially the foot, where thresholds often
  become too large to measure. Central regions give up their
  sensitivity with age more slowly, and even (as in
  the lips) inconsequentially. Similar age-related changes
  have also previously been shown to characterize spatial acuity.

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