Plasticity in the subcortical motor basal ganglia–thalamo–cerebellar network plays a key role in the acquisition and control of long-term memory for new procedural skills, from the formation of population trajectories controlling trained motor skills in the striatum to the adaptation of sensorimotor maps in the cerebellum. However, recent findings demonstrate the involvement of a wider cortical and subcortical brain network in the consolidation and control of well-trained actions, including a brain region traditionally associated with declarative memory—the hippocampus. Here, we probe which role these subcortical areas play in skilled motor sequence control, from sequence feature selection during planning to their integration during sequence execution. An fMRI dataset (N = 24; 14 females) collected after participants learnt to produce four finger press sequences entirely from memory with high movement and timing accuracy over several days was examined for both changes in BOLD activity and their informational content in subcortical regions of interest. Although there was a widespread activity increase in effector-related striatal, thalamic, and cerebellar regions, in particular during sequence execution, the associated activity did not contain information on the motor sequence identity. In contrast, hippocampal activity increased during planning and predicted the order of the upcoming sequence of movements. Our findings suggest that the hippocampus preorders movements for skilled action sequences, thus contributing to the higher-order control of skilled movements that require flexible retrieval. These findings challenge the traditional taxonomy of episodic and procedural memory and carry implications for the rehabilitation of individuals with neurodegenerative disorders.

皮层下运动基底神经节-丘脑-小脑网络的可塑性在获得和控制新程序技能的长期记忆中起着关键作用，从控制纹状体中训练有素的运动技能的种群轨迹的形成到小脑中感觉运动图的适应。然而，最近的研究结果表明，更广泛的皮层和皮层下大脑网络参与巩固和控制训练有素的动作，包括传统上与陈述性记忆相关的大脑区域——海马体。在这里，我们探讨了这些皮层下区域在熟练的运动序列控制中扮演什么角色，从规划期间的序列特征选择到序列执行期间的整合。在参与者在几天内学会完全根据记忆产生四个手指按压序列后收集的 fMRI 数据集（N = 24;14 名女性）检查了 BOLD 活动的变化及其在感兴趣的皮层下区域的信息内容。尽管效应子相关的纹状体、丘脑和小脑区域活动普遍增加，尤其是在序列执行期间，但相关活动不包含有关运动序列身份的信息。相比之下，海马活动在计划期间增加，并预测了即将到来的运动顺序。我们的研究结果表明，海马体为熟练的动作序列预先排序运动，从而有助于对需要灵活检索的熟练动作进行高阶控制。 这些发现挑战了情景记忆和程序记忆的传统分类法，并对神经退行性疾病患者的康复具有影响。