Dataset Information

The influence of visual motion on fast reaching movements to a stationary object.

ABSTRACT: One of the most important functions of vision is to direct actions to objects. However, every time that vision is used to guide an action, retinal motion signals are produced by the movement of the eye and head as the person looks at the object or by the motion of other objects in the scene. To reach for the object accurately, the visuomotor system must separate information about the position of the stationary target from background retinal motion signals-a long-standing problem that is poorly understood. Here we show that the visuomotor system does not distinguish between these two information sources: when observers made fast reaching movements to a briefly presented stationary target, their hand shifted in a direction consistent with the motion of a distant and unrelated stimulus, a result contrary to most other findings. This can be seen early in the hand's trajectory (approximately 120 ms) and occurs continuously from programming of the movement through to its execution. The visuomotor system might make use of the motion signals arising from eye and head movements to update the positions of targets rapidly and redirect the hand to compensate for body movements.

SUBMITTER: Whitney D

PROVIDER: S-EPMC3890253 | biostudies-literature | 2003 Jun

REPOSITORIES: biostudies-literature

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Publications

The influence of visual motion on fast reaching movements to a stationary object.

Whitney David D Westwood David A DA Goodale Melvyn A MA

Nature 20030601 6942

One of the most important functions of vision is to direct actions to objects. However, every time that vision is used to guide an action, retinal motion signals are produced by the movement of the eye and head as the person looks at the object or by the motion of other objects in the scene. To reach for the object accurately, the visuomotor system must separate information about the position of the stationary target from background retinal motion signals-a long-standing problem that is poorly u ...[more]

PMID: 12815432

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Project description:Practice of movement in virtual-reality and other artificially altered environments has been proposed as a method for rehabilitation following neurological injury and for training new skills in healthy humans. For such training to be useful, there must be transfer of learning from the artificial environment to the performance of desired skills in the natural environment. Therefore an important assumption of such methods is that practice in the altered environment engages the same learning and plasticity mechanisms that are required for skill performance in the natural environment. We test the hypothesis that transfer of learning may fail because the learning and plasticity mechanism that adapts to the altered environment is different from the learning mechanism required for improvement of motor skill. In this paper, we propose that a model that separates skill learning and environmental adaptation is necessary to explain the learning and aftereffects that are observed in virtual reality experiments. In particular, we studied the condition where practice in the altered environment should lead to correct skill performance in the original environment. Our 2-mechanism model predicts that aftereffects will still be observed when returning to the original environment, indicating a lack of skill transfer from the artificial environment to the original environment. To illustrate the model prediction, we tested 10 healthy participants on the interaction between a simple overlearned motor skill (straight hand movements to targets in different directions) and an artificially altered visuomotor environment (rotation of visual feedback of the results of movement). As predicted by the models, participants show adaptation to the altered environment and after-effects on return to the baseline environment even when practice in the altered environment should have led to correct skill performance. The presence of aftereffect under all conditions that involved changes in environment demonstrates separation of environmental adaptation and skill learning. Our results support the existence of two distinct learning modules with different adaptation properties. Therefore we suggest that adaptation to an altered environment may not be useful for training new skills.

Dataset Information

The influence of visual motion on fast reaching movements to a stationary object.

Publications

The influence of visual motion on fast reaching movements to a stationary object.

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