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The authors proposed a model of the control of interceptive action over a ground plane (Chardenon, Montagne, Laurent, & Bootsma, 2004). This model is based on the cancellation of the rate of change of the angle between the current position of the target and the direction of displacement (i.e., the bearing angle). While several sources of visual information specify this angle, the contribution of proprioceptive information has not been directly tested. In this study, the authors used a virtual reality setup to study the role of proprioception when intercepting a moving target. In a series of experiments, the authors manipulated proprioceptive information by using the tendon vibration paradigm. The results revealed that proprioception is crucial not only to locate a moving target with respect to the body but also, and more importantly, to produce online displacement velocity changes to intercept a moving target. These findings emphasize the importance of proprioception in the control of interceptive action and illustrate the relevance of our model to account for the regulations produced by the participants.Keywords: proprioception, bearing angle strategy, law of control, tendon vibration, interceptive task Describing how the various sources of information available while performing a goal-directed displacement are involved in the control process is a topical issue. Even if researchers tried to show how a single source of information (e.g., tau or optical acceleration) can underlie the perceptual control of goal-directed displacements under a variety of circumstances, recent contributions provide a different picture. By showing that information underlying the perceptual control of goal-directed displacement could be independent of optic flow, Rushton, Harris, Lloyd, and Wann (1998) opened the door for new kinds of experiments in which the possible use of multiple sources of information, including those independent of the optic flow, were systematically studied. It is now clearly established, both empirically and theoretically, that participants simultaneously manage several sources of information and place priority on the most salient ones depending on task and

Tendon vibration is known to evoke perception of illusory movements, together with motor responses in the muscles antagonistic to those vibrated. In the present study, we assessed the perceptual and motor effects of transcranial magnetic stimulation of the sensorimotor cortex during illusions of hand movements evoked by vibration of wrist muscle tendons. The results showed that transcranial magnetic stimulation could accelerate or decelerate the illusory movements, depending on the site and intensity of magnetic stimulation. Whenever transcranial magnetic stimulation decelerated illusory movements, motor responses decreased, whereas whenever it accelerated illusory movements, motor responses increased. We conclude that motor responses associated with movement illusions have a cortical stage, because they are affected by experimentally induced disruption of activity in intracortical networks.

The recruitment of an additional biomechanical degree of freedom in a unimanual rhythmic task was explored. Subjects were asked to synchronize adduction or abduction of their right index finger with a metronome, the frequency of which was increased systematically. In addition, haptic contact on or off the metronome beat was provided. Results showed that the pattern exhibiting the highest intrinsic stability recruited the vertical plane more than did the less stable one. Moreover, presence and location of haptic contact modulated coordination stability and therefore induced changes in the recruitment of the vertical plane. Thus, a trade-off was shown between coordination stability on the horizontal plane and recruitment of the vertical one. These findings suggest that recruitment of degrees of freedom is governed by general principles of coordination dynamics.