Cortical reorganization and plasticity In the Healthy Brain

背景：皮质重组已被证明发生在成人中枢神经系统。可塑性有助于人类行为的各种形式，包括学习和记忆、不同形式的短期和长期保持以及技能获得。了解这些不同的过程在人类行为中的作用，以及在健康的中枢神经系统中这些不同形式的人类可塑性背后的机制是一个重要的科学问题。 今年的研究结果：今年，我们开发了使用经颅直流刺激(TDC)和经颅磁刺激(TMS)来调节运动学习的新技术，我们确定了程序性运动学习转移的神经底物，其中包括辅助运动区。这项研究目前正在《当代生物学》杂志上发表。我们确定了使用tdcs设计改进的安慰剂试验设计的优势。我们开发了一种新的工具来研究上肢和下肢的参数运动任务中的fMRI。我们研究了老年患者左旋多巴在记忆编码和纹状体多巴胺释放方面的增加。我们在确定自愿驱动在初级运动皮质编码初级运动记忆中的作用方面取得了进展，并确定了在熟练的自行车训练后，人类H反射和其他静态脊髓内回路的可塑性变化。一项特别的努力集中在了解大脑半球间抑制在运动功能和技能获得中的作用。我们发现在运动相关的半球间抑制以及近端和远端手部肌肉之间存在明显的手部差异，同时也促进了我们对程序性知识传递所涉及的神经生理学机制的理解。最重要的发现之一与理解单侧手训练对同侧运动皮质内皮质重组的功能影响有关。 我们未来的计划包括促进我们对大脑刺激对健康大脑中运动学习和记忆形成影响的潜在机制的理解。此外，我们计划了解参与运动学习的两个基本行为过程的大脑区域：程序性运动学习的手动迁移和技能获得的泛化过程。也就是说，学习用一只手完成一项任务的机制允许人类提高不同无关任务的表现。 影响：这些研究将提高我们对人类学习和记忆过程潜在机制的理解，通过获得这种理解，我们将能够开发更有效的干预措施，在必要时使用大脑刺激来调节它们。

Background: Cortical reorganization has been shown to occur in the adult central nervous system. Plasticity contributes to various forms of human behavior including learning and memory, different forms of short and long term retention and skill acquisition. Understanding of the role of these different processes in human behavior and of the mechanisms underlying these various forms of human plasticity in the healthy central nervous system represents an important scientific problem. Findings this year: This year, we developed new techniques to modulate motor learning using transcranial DC stimulation (tDCS) and transcranial magnetic stimulation (TMS), we identified neural substrates underlying transfer of procedural motor learning, which included the supplementary motor areas. This work is presently in press in Current Biology. We identified advantages of the use of tDCS to design improved placebo experimental designs. We developed a novel tool to study fMRI in parametric motor tasks for upper and lower extremities. We characterized levodopa increases in memory encoding and dopamine release in the striatum in the elderly. We advanced in identifying the role of voluntary drive in encoding an elementary motor memory in the primary motor cortex, as well as identified plastic changes in the human H reflex and other intraspinal circuits at rest following skillful cycling training. A particular effort focused on the understanding of the role of interhemispheric inhibition in motor function and skill acquisition. We found well defined intermanual differences in movement-related interhemispheric inhibition as well as differences between proximal and distal hand muscles and also advanced our understanding of the neurophysiological mechanisms involved in transfer of procedural knowledge. One of the most important findings related to the understanding of the functional influences of unilateral hand training on cortical reorganization within the ipsilateral motor cortex. Our future plans include advancing our understanding of the mechanisms underlying the effects of brain stimulation on motor learning and memory formation in the healthy brain. Additionally, we plan to gain understanding on the brain regions that contribute to two fundamental behavioral processes engaged in motor learning: intermanual transfer of procedural motor learning and the process of generalization of skill acquisition. That is, the mechanisms by which learning to perform one task with one hand allow humans to improve performance of different unrelated tasks. Implications: These studies will improve our understanding of the mechanisms underlying human learning and memory processes, and by gaining this understanding, will allow us to develop more effective interventions to modulate them when necessary using brain stimulation.