White matter neuroplasticity and motor learning

人类大脑具有显著的神经可塑性，但大多数研究几乎只关注皮质灰质的神经可塑性。直到最近，我们还认为大脑中的白质结构几乎不可能发生经验依赖性的神经整形改变。最近来自啮齿动物模型的研究表明，这是不正确的；然而，这个问题还没有在人类身上被考虑。在这项拟议的工作中测试的主要假设是，白质，特别是髓鞘，是神经可塑性的，支持与人类大脑运动学习相关的经验依赖性变化。白质占脑组织的40%。髓鞘是大脑中一种关键的结构成分，可以快速有效地进行信息交换，但我们对它如何支持运动学习知之甚少。人类神经成像的最新进展使人脑中髓鞘的活体定量成为可能。多组分T2弛豫成像(MCRI)是一种基于MRI的成像方法，它可以通过绘制脂双层中的水来定量髓鞘的厚度。关键的是，MCRI已经被组织病理学证实为人类大脑中髓鞘含量的一种衡量标准。*我的实验室最近使用MCRI进行的研究表明，髓鞘厚度的增加可以支持健康的年轻人的运动学习。具体地说，我们发现了顶内沟髓鞘厚度增加与练习运动学习任务相关的技能获得速度之间的关系(Lakhani等人，2016)。鉴于我们的研究是第一个显示髓鞘可塑性与人类运动技能学习之间关系的研究，许多问题仍然存在。这些构成了当前提议的基础，我们将在该提议中研究髓鞘可塑性与运动行为、熟练练习和灰质可塑性之间的关系。*如果正如这里所提议的那样，白质，特别是髓鞘，是高度神经可塑性的，并对人类的各种行为操作做出反应，那么神经可塑性的理论将会改变。这一基础知识将极大地推动神经科学和运动学习领域的发展，继续快速扩展关于大脑动态性质的知识。综上所述，这项提案的数据将为我们理解结构神经可塑性如何影响学习提供重要的新见解。

The human brain is remarkably neuroplastic, yet most studies have focused nearly exclusively on neuroplasticity in the cortical gray matter. Until recently we thought that white matter structures in the brain had little potential for experience-dependent neuroplastic change. Recent work from rodent models suggests that this is incorrect; however, this question has not been considered in humans. The main hypothesis being tested in the proposed work is that white matter, specifically myelin, is neuroplastic and supports experience dependent change associated with motor learning in the human brain.******White matter makes up 40% of brain tissue. Myelin is a critical structural component in the brain that allows rapid and effective information exchange, yet we know very little about how it supports motor learning. Recent advances in human neuroimaging have enabled the quantification of myelin in vivo in the human brain. Multi-component T2 relaxation imaging (MCRI) is a MRI based imaging approach that allows quantification of the thickness of myelin by mapping water in the lipid bilayers. Critically, MCRI has been histopathologically validated as a measure of myelin content in human brain. ******Recent work from my lab using MCRI showed that myelin thickness increases to support motor learning in young healthy people. Specifically, we discovered a relationship between increased myelin thickness in the intraparietal sulcus and the rate of skill acquisition associated with practice of a motor learning task (Lakhani et al, 2016). Given that ours was the first study to show a relationship between myelin plasticity and motor skill learning in humans numerous questions remain. These form the basis of the current proposal where we will investigate the relationships between myelin plasticity and: motor behaviour, skilled practice and grey matter plasticity.******If as proposed here white matter, specifically myelin, is highly neuroplastic and responsive to varied behavioural manipulations in humans then theories of neuroplasticity will change. This fundamental knowledge will significantly advance the fields of neuroscience and motor learning, continuing the rapid expansion of knowledge of the dynamic nature of the brain. Taken together the data from this proposal will provide important new insights to our understanding of how structural neuroplasticity affects learning.