School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.
Department of Medicine and Therapeutics, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.
Nat Commun. 2017 Jun 9;8:15834. doi: 10.1038/ncomms15834.
The mechanisms underlying the emergence of learned motor skill representation in primary motor cortex (M1) are not well understood. Specifically, how motor representation in the deep output layer 5b (L5b) is shaped by motor learning remains virtually unknown. In rats undergoing motor skill training, we detect a subpopulation of task-recruited L5b neurons that not only become more movement-encoding, but their activities are also more structured and temporally aligned to motor execution with a timescale of refinement in tens-of-milliseconds. Field potentials evoked at L5b in vivo exhibit persistent long-term potentiation (LTP) that parallels motor performance. Intracortical dopamine denervation impairs motor learning, and disrupts the LTP profile as well as the emergent neurodynamical properties of task-recruited L5b neurons. Thus, dopamine-dependent recruitment of L5b neuronal ensembles via synaptic reorganization may allow the motor cortex to generate more temporally structured, movement-encoding output signal from M1 to downstream circuitry that drives increased uniformity and precision of movement during motor learning.
在初级运动皮层（M1）中产生习得运动技能表现的机制尚不清楚。具体来说，运动学习如何塑造深层输出层 5b（L5b）中的运动表现几乎是未知的。在接受运动技能训练的大鼠中，我们检测到一小部分任务招募的 L5b 神经元不仅变得更具运动编码能力，而且它们的活动也更具结构，并且与运动执行的时间尺度以数十毫秒的精度对齐。在体内在 L5b 诱发的场电位表现出与运动表现平行的持久长时增强（LTP）。皮质内多巴胺去神经支配会损害运动学习，并破坏 LTP 曲线以及任务招募的 L5b 神经元的新兴神经动力学特性。因此，通过突触重组，多巴胺依赖性募集 L5b 神经元集合可能使运动皮层能够从 M1 生成更具时间结构的、运动编码的输出信号，从而驱动运动学习过程中运动的均匀性和精确性增加。
