Ramot Assaf, Taschbach Felix H, Yang Yun C, Hu Yuxin, Chen Qiyu, Morales Bobbie C, Wang Xinyi C, Wu An, Tye Kay M, Benna Marcus K, Komiyama Takaki
Department of Neurobiology, University of California San Diego, La Jolla, CA, USA.
Center for Neural Circuits and Behavior, University of California San Diego, La Jolla, CA, USA.
Nature. 2025 May 7. doi: 10.1038/s41586-025-08962-8.
The primary motor cortex (M1) is central for the learning and execution of dexterous motor skills, and its superficial layer (layers 2 and 3; hereafter, L2/3) is a key locus of learning-related plasticity. It remains unknown how motor learning shapes the way in which upstream regions activate M1 circuits to execute learned movements. Here, using longitudinal axonal imaging of the main inputs to M1 L2/3 in mice, we show that the motor thalamus is the key input source that encodes learned movements in experts (animals trained for two weeks). We then use optogenetics to identify the subset of M1 L2/3 neurons that are strongly driven by thalamic inputs before and after learning. We find that the thalamic influence on M1 changes with learning, such that the motor thalamus preferentially activates the M1 neurons that encode learned movements in experts. Inactivation of the thalamic inputs to M1 in experts impairs learned movements. Our study shows that motor learning reshapes the thalamic influence on M1 to enable the reliable execution of learned movements.
初级运动皮层（M1）对于灵巧运动技能的学习和执行至关重要，其表层（第2层和第3层；以下简称L2/3）是学习相关可塑性的关键位点。目前尚不清楚运动学习如何塑造上游区域激活M1回路以执行所学运动的方式。在这里，我们通过对小鼠M1 L2/3主要输入进行纵向轴突成像，发现运动丘脑是编码专家（经过两周训练的动物）所学运动的关键输入源。然后，我们使用光遗传学来识别学习前后受丘脑输入强烈驱动的M1 L2/3神经元子集。我们发现，丘脑对M1的影响随学习而变化，即运动丘脑优先激活编码专家所学运动的M1神经元。在专家中，对M1的丘脑输入进行失活会损害所学运动。我们的研究表明，运动学习重塑了丘脑对M1的影响，以实现所学运动的可靠执行。
