Motor skill repertoire can be stably retained over long periods, but the neural mechanism that underlies stable memory storage remains poorly understood^{1,2,3,4,5,6,7,8}. Moreover, it is unknown how existing motor memories are maintained as new motor skills are continuously acquired. Here we tracked neural representation of learned actions throughout a significant portion of the lifespan of a mouse and show that learned actions are stably retained in combination with context, which protects existing memories from erasure during new motor learning. We established a continual learning paradigm in which mice learned to perform directional licking in different task contexts while we tracked motor cortex activity for up to six months using two-photon imaging. Within the same task context, activity driving directional licking was stable over time with little representational drift. When learning new task contexts, new preparatory activity emerged to drive the same licking actions. Learning created parallel new motor memories instead of modifying existing representations. Re-learning to make the same actions in the previous task context re-activated the previous preparatory activity, even months later. Continual learning of new task contexts kept creating new preparatory activity patterns. Context-specific memories, as we observed in the motor system, may provide a solution for stable memory storage throughout continual learning.

运动技能库可以长期稳定地保留，但支撑稳定记忆存储的神经机制仍然知之甚少^{1,2,3,4,5,6,7,8}。此外，随着新的运动技能的不断获得，现有的运动记忆是如何维持的尚不清楚。在这里，我们跟踪了小鼠一生中大部分时间学习动作的神经表征，并表明学习的动作与上下文相结合可以稳定保留，从而保护现有记忆在新运动学习期间不被擦除。我们建立了一个持续学习范式，其中小鼠学会了在不同的任务环境中进行定向舔舐，而我们使用双光子成像跟踪运动皮层活动长达六个月。在相同的任务上下文中，驱动定向舔动的活动随着时间的推移是稳定的，几乎没有代表性漂移。当学习新的任务上下文时，出现了新的准备活动来驱动相同的舔舐动作。学习创建了平行的新运动记忆，而不是修改现有的表征。在上一个任务上下文中重新学习执行相同的操作会重新激活之前的准备活动，甚至在几个月后也是如此。对新任务上下文的持续学习不断创造新的准备活动模式。正如我们在运动系统中观察到的那样，特定于上下文的记忆可能为整个持续学习中的稳定记忆存储提供解决方案。