Deafferentation and pointing with visual double-step perturbations

Abstract

The capability of reprogramming movement responses following changes in the visual goal has been studied through the double-step paradigm. These studies have shown that: (a) continuous internal feedback-loops correct unconsciously the dynamic errors throughout the movement; (b) proprioceptive information and/or the efference copy have a privileged status among central processes, insuring on-line regulation of the initial motor commands; and (c) generation of the motor program starts after target presentation, and is continuously updated in the direction of the current internal representation of the target, at least until the onset of hand movement. This main corrective process of the initial program appears to be basically independent of visual reafference from the moving hand. However, the agreement with the possibility of a visuomotor loop, based on the comparison of the new updated representation of the target position and on the information from the moving hand, has not determined whether the correcting process is proprioceptive feedback dependent, or whether internal feedback-loops (efferent copies) are responsible for quick corrections of unfolding motor responses. To answer this question, the present experiment investigated the pointing behavior of a deafferented subject, using a double-step paradigm under various conditions of visual feedback and movement initiation. Overall, the present study (a) clearly showed the capacity of the motor system to modify and correct erroneous trajectories on the mere basis of internal feedback-loops and (b) emphasized the crucial role played by the target jump/arm triggering delay and the importance of the eye efferent copy for providing information about the spatial goal of the movement.

Explorations of anticipatory behavioral control (ABC): a report from the cognitive psychology unit of the University of Würzburg

“…However, it can be taken for granted that the ''sensory-motor transformation'' requires proprioceptive as well as exteroceptive feedback: For example, Cole (1995) describes in his book ''Pride and the Daily Marathon'' how a deafferented patient is unable to maintain an upright position in darkness, which reveals that proprioceptive feedback is indispensable even for the simplest motor control (cf. also Jeannerod 1988; Bard et al 1999;Sainburg et al 1993;Cole and Paillard 1995). And, in an experiment by Proteau et al (1987) blocking of visual feedback causes more disturbances after 2,000 than after 200 repetitions of a simple grasping movement, which shows that exteroceptive (visual) feedback is indispensable even for the simplest movements.…”

Ageing of internal models: from a continuous to an intermittent proprioceptive control of movement

“…These results suggested that the desired state issued from the inverse models and the predicted dynamic state issued from the forward dynamic models could be compared to control the movement before availability of the sensory afferences. Finally, these sensory afferences become available to adjust the ongoing trajectory onto the sensory prediction of the forward sensory models, when necessary (Bard et al 1999;Branch Coslett et al 2008;Desmurget et al 1999;Farrer et al 2003;Hansen and Elliott 2009;Miall and Wolpert 1996;Wolpert and Ghahramani 2000).…”

Online Control of Hand Trajectory and Evolution of Motor Intention in the Parietofrontal System

“…Hand movements can be updated without awareness of the target's shift, such as during ocular saccades (Blouin et al, 1995), and in the absence of visual control (Pélisson et al, 1986) or limb proprioception (Bard et al, 1999;Sarlegna et al, 2006). Online corrections might rely on a nonsensory feedback mechanism based on motor outflow (Desmurget and Grafton, 2000), as well as on sensory information (Blouin et al, 1995;Desmurget et al, 1999).…”