ANOMALOUS SENSATIONS FOLLOWING PROLONGED TACTILE STIMULATION

Animal studies have demonstrated that tactile experience can alter central organization of somatosensory information. The present study examined the effect of prolonged tactile stimulation on spatial sensitivity in human subjects. Four subjects received repetitive, tactile stimulation presented on the volar surface of the forearm. The tactile stimuli were delivered through small vibrators worn by the subjects. After a period of 5-9 weeks of wearing the vibrators, three of the four subjects reported anomalous sensations when attempting to localize tactile stimuli. Subjects had difficulty in localizing stimuli and reported sensations of pressure and diffuseness. Single stimuli would sometimes evoke double and triple sensations separated by as much as 20 cm. After removing the vibrators, subjects continued to report anomalous sensations for up to 15 weeks. These results are interpreted within the framework of a model of central, neural reorganization.