Department of Bioengineering, Stanford University, Stanford, CA 94305, USA.
Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA; Neurosciences Graduate Program, Stanford University, Stanford, CA 94305, USA.
Neuron. 2020 Apr 22;106(2):329-339.e4. doi: 10.1016/j.neuron.2020.01.019. Epub 2020 Feb 12.
Current theories suggest that an error-driven learning process updates trial-by-trial to facilitate motor adaptation. How this process interacts with motor cortical preparatory activity-which current models suggest plays a critical role in movement initiation-remains unknown. Here, we evaluated the role of motor preparation during visuomotor adaptation. We found that preparation time was inversely correlated to variance of errors on current trials and mean error on subsequent trials. We also found causal evidence that intracortical microstimulation during motor preparation was sufficient to disrupt learning. Surprisingly, stimulation did not affect current trials, but instead disrupted the update computation of a learning process, thereby affecting subsequent trials. This is consistent with a Bayesian estimation framework where the motor system reduces its learning rate by virtue of lowering error sensitivity when faced with uncertainty. This interaction between motor preparation and the error-driven learning system may facilitate new probes into mechanisms underlying trial-by-trial adaptation.
目前的理论表明，错误驱动的学习过程会逐次更新，以促进运动适应。目前的模型表明，这种过程与运动皮层预备活动如何相互作用——运动皮层预备活动在运动启动中起着关键作用——仍然未知。在这里，我们评估了运动准备在视觉运动适应中的作用。我们发现，准备时间与当前试验的误差方差和后续试验的平均误差呈反比关系。我们还发现了因果证据，表明运动准备期间的皮质内微刺激足以破坏学习。令人惊讶的是，刺激并没有影响当前的试验，而是破坏了学习过程的更新计算，从而影响了后续的试验。这与贝叶斯估计框架一致，在该框架中，运动系统通过在面对不确定性时降低误差敏感性来降低学习率。运动准备和错误驱动学习系统之间的这种相互作用可能有助于深入了解逐次适应的机制。
