1. Previous studies have used tendon vibration to investigate kinesthetic illusions in the isometric limb and end point control in the moving limb. These previous studies have shown that vibration distorts the perceptions of static joint angle and movement and causes systematic errors in the end point of movement. In this paper we describe the effects of tendon vibration during movement while human subjects performed a proprioceptively coordinated motor task. In an earlier study we showed that the CNS coordinates this motor task-a movement sequence-with proprioceptive information related to the dynamic position and velocity of the limb. 2. When performing this movement sequence, each subject sat at a table and opened the right hand as the right elbow was passively rotated in the extension direction through a prescribed target angle. Vision of the arm was prevented, and the movement velocity was changed randomly from trial to trial, leaving proprioception as the only useful source of kinematic information with which to perform the task. 3. In randomly occurring trials, vibration was applied to the tendon of the biceps brachii, a muscle that lengthens during elbow extension. In some experiments the timing of tendon vibration was varied with respect to the onset of elbow rotation, and in other experiments the frequency of vibration was varied. In each experiment we compared the accuracy of the subject's response (i.e., the elbow angle at which the subject opened the hand) in trials with tendon vibration with the accuracy in trials without tendon vibration. 4. The effect of tendon vibration depended on the frequency of vibration. When the biceps tendon was vibrated at 20 Hz, subjects opened the hand after the elbow passed through the target angle ("overshooting"). Overshooting is consistent with an underestimate of the actual displacement or velocity of the elbow. Vibration at 30 Hz had little or no effect on the elbow angle at hand opening. Vibration at 40 Hz caused subjects to open the hand before the elbow reached the target angle ("undershooting"). Undershooting is consistent with an overestimate of the actual displacement or velocity of the elbow. The size of the error depended on the velocity of the passively imposed elbow rotation. 5. The effect of tendon vibration also depended on the timing of vibration. If 40-Hz vibration began at the onset of movement, the subject undershot the target. If 40-Hz vibration started 5 s before movement onset and continued throughout the movement, the undershoot error increased in magnitude. However, if 40-Hz vibration started 5 s before movement onset and then stopped at movement onset, the subject overshot the target. When vibration was shut off during movement, a transition occurred from an over-shooting error to an undershooting error at a time that depended on the velocity of elbow rotation. 6. In a separate experiment, subjects were instructed to match either the perceived dynamic position or the perceived velocity of rotation imposed on the right elbow by actively rotati...

1. Recent studies have shown that the CNS uses proprioceptive information to coordinate multijoint movement sequences; proprioceptive input related to the kinematics of one joint rotation in a movement sequence can be used to trigger a subsequent joint rotation. In this paper we adopt a broad definition of "proprioception," which includes all somatosensory information related to joint posture and kinematics. This paper addresses how the CNS uses proprioceptive information related to the velocity and position of joints to coordinate multijoint movement sequences. 2. Normal human subjects sat at an experimental apparatus and performed a movement sequence with the right arm without visual feedback. The apparatus passively rotated the right elbow horizontally in the extension direction with either a constant velocity trajectory or an unpredictable velocity trajectory. The subjects' task was to open briskly the right hand when the elbow passed through a prescribed target position, similar to backhand throwing in the horizontal plane. The randomization of elbow velocities and the absence of visual information was used to discourage subjects from using any information other than proprioceptive input to perform the task. 3. Our results indicate that the CNS is able to extract the necessary kinematic information from proprioceptive input to trigger the hand opening at the correct elbow position. We estimated the minimal sensory conduction and processing delay to be 150 ms, and on the basis of this estimate, we predicted the expected performance with different degrees of reduced proprioceptive information. These predictions were compared with the subjects' actual performances, revealing that the CNS was using proprioceptive input related to joint velocity in this motor task. To determine whether position information was also being used, we examined the subjects' performances with unpredictable velocity trajectories. The results from experiments with unpredictable velocity trajectories indicate that the CNS extracts proprioceptive information related to both the velocity and the angular position of the joint to trigger the hand movement in this movement sequence. 4. To determine the generality of proprioceptive triggering in movement sequences, we estimated the minimal movement duration with which proprioceptive information can be used as well as the amount of learning required to use proprioceptive input to perform the task. The temporal limits for proprioceptive processing in this movement task were established by determining the minimal movement time during which the task could be performed.(ABSTRACT TRUNCATED AT 400 WORDS)