Gabitov Ella, Lungu Ovidiu, Albouy Geneviève, Doyon Julien
McConnell Brain Imaging Center, Montreal Neurological Institute, Montreal, QC, Canada.
Functional Neuroimaging Unit, Centre de recherche de l'Institut universitaire de gériatrie de Montréal, Montreal, QC, Canada.
Front Neurol. 2019 Nov 27;10:1242. doi: 10.3389/fneur.2019.01242. eCollection 2019.
Recently, an increasing interest in investigating interactions between brain regions using functional connectivity (FC) methods has shifted the initial focus of cognitive neuroimaging research from localizing functional circuits based on task activation to mapping brain networks based on intrinsic FC dynamics. Leveraging the advantages of the latter approach, it has been shown that despite primarily invariant intrinsic organization of the large-scale functional networks, interactions between and within these networks significantly differ between various behavioral and cognitive states. These differences presumably indicate transient reconfiguration of functional connections-an instantaneous process that flexibly mediates and calibrates human behavior according to momentary demands of the environment. Nevertheless, the specificity of these reconfigured FC patterns to the task at hand and their relevance to adaptive processes during learning remain elusive. To address this knowledge gap, we investigated (1) to what extent FC within the somatomotor network is reconfigured during motor skill practice, and (2) how these changes are related to learning. We applied a seed-driven FC approach to data collected during a continuous task-free condition, so-called resting state, and during a motor sequence learning task using functional magnetic resonance imaging. During the task, participants repeatedly performed a short five-element sequence with their non-dominant (left) hand. As predicted, such unimanual sequence production was associated with lateralized activation of the right somatomotor cortex (SMC). Using this "active" region as a seed, here we show that unimanual performance of the motor sequence relies on functional segregation between the two SMC and selective integration between the "active" SMC and supplementary motor area. Whereas, greater segregation between the two SMC was associated with gains in performance rate, greater segregation within the "active" SMC itself was associated with more consistent performance by the end of training. Nether the resting-state FC patterns within the somatomotor network nor their relative modulation by the task state predicted these behavioral benefits of learning. Our results suggest that task-induced FC changes reflect reconfiguration of the connectivity patterns within the somatomotor network rather than a simple amplification or silencing of its intrinsic dynamics. Such reconfiguration not only supports motor behavior but may also predict learning.
最近，利用功能连接（FC）方法研究脑区之间相互作用的兴趣日益浓厚，这使得认知神经成像研究的最初重点从基于任务激活定位功能回路，转向基于内在FC动态绘制脑网络。利用后一种方法的优势，研究表明，尽管大规模功能网络的内在组织基本不变，但这些网络之间以及内部的相互作用在各种行为和认知状态下存在显著差异。这些差异可能表明功能连接的瞬时重新配置——这是一个根据环境的瞬间需求灵活调节和校准人类行为的即时过程。然而，这些重新配置的FC模式与手头任务的特异性及其与学习过程中适应性过程的相关性仍然难以捉摸。为了填补这一知识空白，我们研究了：（1）在运动技能练习过程中，躯体运动网络内的FC在多大程度上重新配置；（2）这些变化如何与学习相关。我们将种子驱动的FC方法应用于在连续无任务状态（即所谓的静息状态）以及使用功能磁共振成像的运动序列学习任务期间收集的数据。在任务期间，参与者用其非优势（左）手反复执行一个简短的五元素序列。正如预期的那样，这种单手序列生成与右侧躯体运动皮层（SMC）的偏侧化激活相关。以这个“活跃”区域作为种子，我们在此表明，运动序列的单手执行依赖于两个SMC之间的功能分离以及“活跃”SMC与辅助运动区之间的选择性整合。然而，两个SMC之间更大的分离与表现率的提高相关，而“活跃”SMC自身内部更大的分离与训练结束时更一致的表现相关。躯体运动网络内的静息态FC模式及其受任务状态的相对调节均未预测到学习的这些行为益处。我们的结果表明，任务诱导的FC变化反映了躯体运动网络内连接模式的重新配置，而不是其内在动态的简单增强或抑制。这种重新配置不仅支持运动行为，还可能预测学习情况。
