Functional Neuroimaging Unit, CRIUGM, Montreal, QC, Canada; University of Montreal, Montreal, Canada.
Functional Neuroimaging Unit, CRIUGM, Montreal, QC, Canada; McConnell Brain Imaging Center, Montreal Neurological Institute, McGill University, Montreal, Canada.
Neuroscience. 2019 Mar 15;402:104-115. doi: 10.1016/j.neuroscience.2018.12.049. Epub 2019 Jan 4.
Ample evidence suggests that consolidation of the memory trace associated with a newly acquired motor sequence is supported by thalamo-cortical spindle activity during subsequent sleep, as well as functional changes in a distributed cortico-striatal network. To date, however, no studies have investigated whether the structural white matter connections between these regions affect motor sequence memory consolidation in relation with sleep spindles. Here, we used diffusion weighted imaging (DWI) tractography to reconstruct the major fascicles of the cortico-striato-pallido-thalamo-cortical loop in both young and older participants who were trained on an explicit finger sequence learning task before and after a daytime nap. Thereby, this allowed us to examine whether post-learning sleep spindles measured using polysomnographic recordings interact with consolidation processes and this specific neural network. Our findings provide evidence corroborating the critical role of NREM2 thalamo-cortical sleep spindles in motor sequence memory consolidation, and show that the post-learning changes in these neurophysiological events relate specifically to white matter characteristics in thalamo-cortical fascicles. Moreover, we demonstrate that microstructure along this fascicle relates indirectly to offline gains in performance through an increase of spindle density over motor-related cortical areas. These results suggest that the integrity of thalamo-cortical projections, via their impact on sleep spindle generation, may represent one of the critical mechanisms modulating the expression of sleep-dependent offline gains following motor sequence learning in healthy adults.
大量证据表明，在随后的睡眠期间，丘脑皮质纺锤波活动以及皮质纹状体网络的功能变化，支持与新获得的运动序列相关的记忆痕迹的巩固。然而，迄今为止，尚无研究调查这些区域之间的结构性白质连接是否会影响与睡眠纺锤波相关的运动序列记忆巩固。在这里，我们使用弥散张量成像（DWI）束追踪技术，在接受明确手指序列学习任务训练的年轻和年长参与者中重建皮质纹状体苍白球丘脑皮质环路的主要束。这样，我们就可以检查使用多导睡眠图记录测量的学习后睡眠纺锤波是否与巩固过程和这个特定的神经网络相互作用。我们的研究结果提供了证据，证明了 NREM2 丘脑皮质睡眠纺锤波在运动序列记忆巩固中的关键作用，并表明这些神经生理事件的学习后变化与丘脑皮质束中的白质特征特别相关。此外，我们证明，通过增加与运动相关的皮质区域的纺锤波密度，该束中的微观结构与离线表现的提高间接相关。这些结果表明，通过影响睡眠纺锤波的产生，丘脑皮质投射的完整性可能代表调节健康成年人运动序列学习后睡眠依赖离线增益表达的关键机制之一。
