Cortical reorganization and plasticity In the Healthy Brain

背景资料： 皮质重组发生在成人中枢神经系统。可塑性有助于各种形式的人类行为，包括运动学习和记忆形成，巩固，再巩固以及短期和长期保持。理解这些不同的行为过程的作用以及这些不同形式的人类可塑性在技能获得过程中的机制是非常重要的。 今年的发现： 为了了解奖励对学习的影响，我们进行了两个研究。 在第一个实验中，我们假设大规模的额纹状体-边缘系统网络的基线功能连接可以预测奖励学习中随后的个体间差异。静息状态下的功能性磁共振成像获得了两组受试者，然后训练的视觉程序学习任务有或没有奖励反馈。然后，我们测试了两组中额纹-边缘系统网络内的基线功能连接是否预测了训练后立即、24小时和1个月测量的记忆强度。我们发现，额纹-边缘系统网络的连通性预测了奖励学习组的个体间差异，但在无奖励学习组中则不然。长期记忆的预测能力最强。在两个控制网络，额顶颞语言网络和背侧注意网络中，连接性和基于奖励的记忆之间没有类似的联系。结果表明，额纹-边缘网络的基线功能连接预测奖励学习的长期保留。 在第二个中，我们研究了奖励对绩效的影响的个体间差异，这些差异是普遍存在的，但人们对它们的了解很少，有些人比其他人更依赖于他们行动的奖励结果。奖励依赖性的这种变异性的起源是未知的。我们测试了健康人的奖励依赖和大脑结构之间的关系。受试者接受了视觉技能获取任务的训练，并在有或没有奖励的情况下接受了绩效反馈。奖励依赖被定义为奖励与后续绩效之间的统计试验关系。我们报告了奖励依赖和外侧前额叶皮层之间的显着关系，其中区域灰质体积预测奖励依赖，但不是反馈。多体素模式分析证实了这种关系的解剖特异性。这些结果确定了一个可能的解剖学标记奖励的前瞻性影响的表现，这可能是相关的神经康复设置。

Background: Cortical reorganization occurs in the adult central nervous system. Plasticity contributes to various forms of human behavior including motor learning and memory formation, consolidation, reconsolidation and short and long term retention. It is very important to understand the role of these different behavioral processes and of the mechanisms underlying these various forms of human plasticity during skill acquisition. Findings this year: In reference to understanding the influence of Reward on learning we carried out two studies. In the first one, we postulated that baseline functional connectivity in a large-scale frontostriatal-limbic network could predict subsequent interindividual variability in rewarded learning. Resting-state functional MRI was acquired in two groups of subjects who then trained on a visuomotor procedural learning task with or without reward feedback. We then tested whether baseline functional connectivity within the frontostriatal-limbic network predicted memory strength measured immediately, 24 h and 1 month after training in both groups. We found that connectivity in the frontostriatal-limbic network predicted interindividual variability in the rewarded but not in the unrewarded learning group. Prediction was strongest for long-term memory. Similar links between connectivity and reward-based memory were absent in two control networks, a fronto-parieto-temporal language network and the dorsal attention network. The results indicate that baseline functional connectivity within the frontostriatal-limbic network predicts long-term retention of rewarded learning. In the second one, we studied interindividual differences in the effects of reward on performance which are prevalent and poorly understood, with some individuals being more dependent than others on the rewarding outcomes of their actions. The origin of this variability in reward dependence is unknown. We tested the relationship between reward dependence and brain structure in healthy humans. Subjects trained on a visuomotor skill-acquisition task and received performance feedback in the presence or absence of reward. Reward dependence was defined as the statistical trial-by-trial relation between reward and subsequent performance. We report a significant relationship between reward dependence and the lateral prefrontal cortex, where regional gray-matter volume predicted reward dependence but not feedback alone. Multivoxel pattern analysis confirmed the anatomical specificity of this relationship. These results identified a likely anatomical marker for the prospective influence of reward on performance, which may be of relevance in neurorehabilitative settings.