Enhanced Tactile (Touch) Spatial Acuity in Upper Limb Amputees
Enhanced Tactile (Touch) Spatial Acuity in Upper Limb Amputees
This study will examine whether tactile (touch) abilities at the lip are more acute in people
 with upper limb amputation compared with healthy normal volunteers. People with an amputated
 upper limb have an expanded brain representation of the lip that may correlate with
 heightened tactile spatial acuity.

 Normal volunteers will be recruited for this study. Candidates will be screened with physical
 and neurological examinations. (Amputee volunteers will be studied at the amputee clinic at
 the University of Tubingen, Germany.)

 Participants will sit comfortably in a chair, wearing a blindfold, during the following
 experiments:

 -  Plastic domes with grooves are placed on parts of the lower lip on either side for a few
 seconds. The volunteer is then asked to identify the direction of the grooves relative
 to the long axis of the lip.

 -  The participant's arm is placed in a cast and the index finger is immobilized. The same
 test done on the lip is repeated on the distal part of the index finger.

 Each part of the test lasts about 20 minutes, and the entire experiment takes about 2 hours.
Upper limb amputation leads to expansion of the cortical representation of the lip into the
 adjacent deafferented hand representation. It is conceivable that this enlargement of the lip
 representation may translate into a behavioral gain. The purpose of this protocol is to test
 the hypothesis that upper limb amputation in humans results in higher tactile spatial acuity
 at the lip. This would represent the first demonstration of chronic deafferentation-induced
 behavioral gains within the somatosensory system.
INCLUSION CRITERIA:

 Normal volunteers who are willing and able to stay relaxed and collaborative for a period
 of up to 2 hours.

 Subjects with upper limb amputation more than one year before testing.

 EXCLUSION CRITERIA:

 Neurological or psychiatric disease

 Excessive callus at the palm of the fingers

 Subjects, who are unable to perform or understand the task