Temporal lobe connections and parallel networks for memory: possible mechanisms of resilience and recovery after stroke

老年记忆力衰退是医学研究面临的一个重大挑战，给个人、社会和财政带来越来越大的负担。中风是一个重要的原因。中风协会最近的一项调查强调，记忆问题是中风幸存者未满足需求的主要领域之一。记忆依赖于大脑中广泛分布的网络。这些网络由一束束白色物质连接，这些物质基本上是大脑的线路。这些联系可能很重要。然而，令人惊讶的是，我们对中风后记忆中的连接或记忆崩溃的作用知之甚少，尽管轻微中风往往会损害白色物质。部分原因是，直到最近，我们才能从大脑图像（例如MRI）中识别和描绘出记忆的重要连接。我们最近的研究使用了一种称为弥散张量MRI的技术来解决这一挑战，并调查可能对记忆很重要的连接。研究发现，一个被称为穹窿的特殊区域在健康大脑和衰老过程中最为重要。然而，在记忆衰退的早期阶段，替代途径变得不成比例地重要。这导致了这样一种想法，即早期记忆衰退的个体可能特别容易受到这些替代区域的伤害。这个项目的目的是通过调查中风的影响来测试这个想法。对中风影响的研究也将增加对记忆在正常大脑中是如何组织的知识。该项目将侧重于两组个体：一组近期中风影响白色物质的患者，以及一组来自荷兰鹿特丹健康成人正在进行的研究的个体，这是世界上同类研究的领先者。两组都将进行MRI，包括弥散张量MRI和认知评估。第二组的重要性在于，他们已经被跟踪了多年，因此在中风前可以获得关于记忆和认知轨迹的信息，这是对转移脆弱性的最强有力的测试。将评估大脑中颞叶连接的损伤模式，并将其与中风对记忆的影响联系起来。我们将确定一年内未受破坏的地区对恢复的贡献。最后，尖端的计算图像分析技术将被应用于更详细地尝试和预测记忆概况，并从大脑图像中提取有关预后的最大信息。到目前为止，这项强大的技术已被应用于诊断，但不是预后。了解决定脆弱性的因素，弹性或记忆系统的恢复将有助于新的治疗方法的逻辑发展。此外，更准确地预测预后的能力将有助于将治疗目标对准最有可能受益的患者，并将提高我们可以向患者提供的关于他们可能如何康复的信息的质量。

Memory breakdown in older age is a major challenge for medical research, with an increasing burden in personal, societal and fiscal terms. Stroke is an important cause. A recent survey by the Stroke Association highlighted memory problems as one of the leading areas of unmet need in stroke survivors. Memory depends on widespread networks in the brain. These networks are connected by bundles of white matter, which essentially are the wiring of the brain. The connections are likely to be important. However, we know surprisingly little about the role of connections in memory or memory breakdown after stroke, despite the fact that minor strokes often damage white matter. Part of the reason is that until recently, it was not possible to identify and delineate the important connections for memory from brain images (e.g. MRI).Our recent research used a technique called diffusion tensor MRI to tackle this challenge and investigate connections likely to be important for memory. A particular tract called the fornix was found to be most important in the healthy brain and in ageing. However, in individuals at an early stage of memory decline alternative pathways became disproportionately more important. This led to the idea that individuals with early memory decline might be especially vulnerable to injury to these alternative tracts. The purpose of this project will be to test this idea by investigating the effects of stroke. Study of the impact of stroke will also add to knowledge of how memory is organised in the normal brain. The project will focus on two groups of individuals: a group of patients with recent stroke affecting white matter and a group of individuals from an ongoing study of healthy adults drawn from the population of Rotterdam, the Netherlands, the leading study of its kind in the world. Both groups will have MRI, including diffusion tensor MRI, and cognitive assessment. The importance of the second group lies in the fact that they have already been followed for a number of years, so information will be available on memory and cognitive trajectory before stroke, providing the strongest test of the idea of shifting vulnerability. The pattern of damage to temporal lobe connections in the brain will be assessed and related to the impact of stroke on memory. We will determine how undamaged tracts contribute to recovery over one year. Finally, cutting-edge computational image analysis techniques will be applied to try and predict memory profile in more detail and extract maximum information about prognosis from brain images. To date, this powerful technology has been applied to diagnosis but not to prognosis.Understanding of the factors that dictate vulnerability, resilience or recovery of memory systems will aid the logical development of new treatments. Further, the ability to predict prognosis more accurately will help to target treatments to patients most likely to benefit and will improve the quality of information we can give to patients about how they are likely to recover.