Department of Neuroscience, Columbia University Medical Center, New York, NY 10032, USA; Zuckerman Institute, Columbia University, New York, NY 10027, USA.
Zuckerman Institute, Columbia University, New York, NY 10027, USA; Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA.
Neuron. 2018 Feb 21;97(4):953-966.e8. doi: 10.1016/j.neuron.2018.01.004. Epub 2018 Feb 1.
Primate motor cortex projects to spinal interneurons and motoneurons, suggesting that motor cortex activity may be dominated by muscle-like commands. Observations during reaching lend support to this view, but evidence remains ambiguous and much debated. To provide a different perspective, we employed a novel behavioral paradigm that facilitates comparison between time-evolving neural and muscle activity. We found that single motor cortex neurons displayed many muscle-like properties, but the structure of population activity was not muscle-like. Unlike muscle activity, neural activity was structured to avoid "tangling": moments where similar activity patterns led to dissimilar future patterns. Avoidance of tangling was present across tasks and species. Network models revealed a potential reason for this consistent feature: low tangling confers noise robustness. Finally, we were able to predict motor cortex activity from muscle activity by leveraging the hypothesis that muscle-like commands are embedded in additional structure that yields low tangling.
灵长类运动皮层投射到脊髓中间神经元和运动神经元，这表明运动皮层活动可能主要由类似肌肉的指令主导。在伸手过程中的观察结果支持了这一观点，但证据仍然存在分歧和争议。为了提供不同的视角，我们采用了一种新的行为范式，便于比较随时间演变的神经和肌肉活动。我们发现单个运动皮层神经元表现出许多类似肌肉的特性，但群体活动的结构却不像肌肉。与肌肉活动不同，神经活动的结构旨在避免“缠绕”：即相似的活动模式导致未来模式不同的时刻。这种避免缠绕的现象在不同任务和物种中都存在。网络模型揭示了这种一致特征的潜在原因：低缠绕能提高噪声鲁棒性。最后，我们通过利用肌肉活动中嵌入的低缠绕的额外结构的假设，从肌肉活动中预测了运动皮层的活动。
