Hudson Todd E, Landy Michael S
Department of Psychology, New York University, New York, NY 10003, USA.
J Vis. 2012 Jan 6;12(1):4. doi: 10.1167/12.1.4.
In the study of visual-motor control, perhaps the most familiar findings involve adaptation to externally imposed movement errors. Theories of visual-motor adaptation based on optimal information processing suppose that the nervous system identifies the sources of errors to effect the most efficient adaptive response. We report two experiments using a novel perturbation based on stimulating a visually induced reflex in the reaching arm. Unlike adaptation to an external force, our method induces a perturbing reflex within the motor system itself, i.e., perturbing forces are self-generated. This novel method allows a test of the theory that error source information is used to generate an optimal adaptive response. If the self-generated source of the visually induced reflex perturbation is identified, the optimal response will be via reflex gain control. If the source is not identified, a compensatory force should be generated to counteract the reflex. Gain control is the optimal response to reflex perturbation, both because energy cost and movement errors are minimized. Energy is conserved because neither reflex-induced nor compensatory forces are generated. Precision is maximized because endpoint variance is proportional to force production. We find evidence against source-identified adaptation in both experiments, suggesting that sensory-motor information processing is not always optimal.
在视觉运动控制的研究中，或许最广为人知的发现涉及对外部施加的运动误差的适应。基于最优信息处理的视觉运动适应理论认为，神经系统会识别误差来源，以实现最有效的适应性反应。我们报告了两项实验，这些实验使用了一种基于刺激伸展手臂中视觉诱发反射的新型扰动。与适应外力不同，我们的方法在运动系统自身内部诱发一种扰动反射，即扰动力是自我产生的。这种新方法能够对误差源信息用于产生最优适应性反应这一理论进行检验。如果视觉诱发反射扰动的自我产生源被识别，最优反应将通过反射增益控制来实现。如果该源未被识别，则应产生一种补偿力来抵消反射。增益控制是对反射扰动的最优反应，这既是因为能量消耗和运动误差都被最小化了。能量得以守恒，因为既没有产生反射诱发力，也没有产生补偿力。精度得以最大化，因为端点方差与力的产生成正比。我们在两项实验中都发现了反对已识别源适应的证据，这表明感觉运动信息处理并不总是最优的。
