Department of Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, Maryland 21205, USA.
J Neurosci. 2011 May 11;31(19):7102-10. doi: 10.1523/JNEUROSCI.0273-11.2011.
It has been hypothesized that the generalization patterns that accompany learning carry the signatures of the neural systems that are engaged in that learning. Reach adaptation in force fields has generalization patterns that suggest primary engagement of a neural system that encodes movements in the intrinsic coordinates of joints and muscles, and lesser engagement of a neural system that encodes movements in the extrinsic coordinates of the task. Among the cortical motor areas, the intrinsic coordinate system is most prominently represented in the primary sensorimotor cortices. Here, we used transcranial direct current stimulation (tDCS) to alter mechanisms of synaptic plasticity and found that when it was applied to the motor cortex, it increased generalization in intrinsic coordinates but not extrinsic coordinates. However, when tDCS was applied to the posterior parietal cortex, it had no effects on learning or generalization in the force field task. The results suggest that during force field adaptation, the component of learning that produces generalization in intrinsic coordinates depends on the plasticity in the sensorimotor cortex.
有人假设，伴随学习而来的泛化模式携带着参与学习的神经系统的特征。在力场中进行的伸手适应具有泛化模式，这表明主要涉及到一种编码关节和肌肉内在坐标运动的神经系统，以及较少涉及到编码任务外在坐标运动的神经系统。在皮质运动区域中，内在坐标系在初级感觉运动皮层中最为突出。在这里，我们使用经颅直流电刺激（tDCS）来改变突触可塑性的机制，发现当它应用于运动皮层时，它会增加内在坐标的泛化，但不会增加外在坐标的泛化。然而，当 tDCS 应用于后顶叶皮层时，它对力场任务中的学习或泛化没有影响。结果表明，在力场适应过程中，产生内在坐标泛化的学习成分取决于感觉运动皮层的可塑性。
