Exteroceptive vibration-induced finger flexion reflex in man.

A tonic finger flexion reflex, induced by mechanical vibration (100 Hz) of the fingers, was studied in 20 healthy subjects. The outcome of nerve blocking experiments indicated that the reflex is mainly exteroceptive, distinct from the tonic vibration reflex of muscle spindle origin. Mechanoreceptors with fast conducting nerve fibres in the distal phalanx seem to constitute the major afferent source. We suggest that afferent signals from such receptors by a feedback mechanism can influence the motor performance of the exploring fingers.