MODIFICATION OF HUMAN PAIN THRESHOLD BY SPECIFIC TACTILE RECEPTORS

The effects of conditioning vibrotactile stimulation of particular tactile receptor groups on thresholds to painful electric stimuli were studied in 7 healthy [human] adults. Preferentially Pacinian afferents were activated with conditioning sinusoidal vibrations of 240 Hz at 20 and 200 .mu.m amplitudes and preferentially non-Pacinian tactile fibers were activated with conditioning sinusoidal vibrations of 20 Hz at 200 and 400 .mu.m aplitudes. None of the subjects showed pain threshold elevation during activation of non-Pacinian tactile fibers. Of the 7 subjects, 6 showed significant pain threshold elevation with conditioning vibratory stimulus of 240 Hz at 200 .mu.m amplitude, and 4 subjects showed significantly elevated pain thresholds and conditioning stimulus of 240 Hz at 20 .mu.m amplitude. The activation of Pacinian afferents causes inhibition of pain conducting pathways.