Dissecting an asymmetric brain area implicated in sleep maintenance

剖析与睡眠维持有关的不对称大脑区域

• 批准号: BB/X01536X/1
• 负责人: Jason Rihel
• 金额: $ 90.37万
• 依托单位: University College London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FX01536X%2F1
• 关键词: Dissecting; asymmetric; brain; area; implicated

Just as most humans prefer to use either their right or left hand, asymmetries are built into the brains of most animals that are otherwise symmetrical. While we know some details about how these asymmetries arise during development, we are still discovering the functional importance of these asymmetries on thinking and behavior. One behavior for which little is known about the role of left-right asymmetry is sleep. Since sleep is essential for normal health and cognitive function across our lifespan, understanding the underlying organizing principles of sleep regulation is of great importance.While studying sleep changes of zebrafish that have mutations associated with autism in humans, we discovered a new and unexpected brain asymmetry. Specifically, while normal zebrafish begin to lengthen the time they spend asleep in the evening before lights out, zebrafish lacking the autism risk gene called chd8 fail to do so. Using methods to visualize the brain activity of larval zebrafish, which are optically translucent in early stages, we found larvae that lack chd8 have high brain activity only on the right side of the midbrain during the evening. This led to the further discovery of a previously unreported physical asymmetry in same region of the brain. In this project, we now plan to investigate this new asymmetry by determining whether it follows the same developmental rules as other asymmetric brain regions, how this development may go wrong in zebrafish autism models, and whether and how this asymmetry is important for the regulation of sleep duration. The zebrafish is an excellent system in which to study the links between brain asymmetries and sleep because of existing experimental tools to visualize and manipulate both properties. For example, there are zebrafish mutants and experimental manipulations that lead to altered brain asymmetries, such as animals with "double-left", "double-right" or "reversed" brain structures. We plan to test whether these manipulations also lead to changes in the asymmetry of this sleep regulating brain area, which will give us important clues about the extent to which this area follows known developmental rules for the creation of asymmetries. We will also use automated videotracking of zebrafish across the day-night cycle to see if changes in asymmetry affect sleep durations, which we can assess by measuring how long the zebrafish stay inactive in sleep states.Using genetics, we will also label this midbrain asymmetry with fluorescent proteins to see how this area connects with the rest of the brain such as known sleep-regulating centers, to observe what molecules are selectively expressed in this region, and to understand how the formation of this area is disrupted in the short-sleeping animals that lack chd8. These experiments will tell us more about the structural and molecular properties of this asymmetry and will inform how the area may be regulating sleep.Finally, we will test the role of this asymmetric area in sleep by taking direct control of the activity of this area. For example, we can selectively remove this area using laser ablation and ask whether this area is required for proper sleep durations. We will also use genetic interventions to put light- or drug-inducible proteins that can drive neuronal excitability specifically into this asymmetric area. This will give us direct control over the activity of this region, allowing us to test whether turning the area on or off is capable of altering zebrafish sleep. Together these experiments will give us a new understanding of how brain asymmetries regulate sleep duration and knowledge about how this regulation might be altered in human disorders such as autism.

就像大多数人类喜欢使用右手或左手一样，大多数动物的大脑也存在不对称性，否则它们就是对称的。虽然我们知道这些不对称性在发育过程中如何产生的一些细节，但我们仍然在发现这些不对称性在思维和行为上的功能重要性。人们对左右不对称的作用知之甚少的一种行为是睡眠。由于睡眠对我们一生中正常的健康和认知功能至关重要，了解睡眠调节的潜在组织原理非常重要。在研究与人类自闭症相关的突变斑马鱼的睡眠变化时，我们发现了一种新的、意想不到的大脑不对称。具体地说，虽然正常的斑马鱼会在熄灯前延长晚上的睡眠时间，但缺乏自闭症风险基因CHD8的斑马鱼却无法做到这一点。使用可视化方法对早期光学半透明的斑马鱼幼体的大脑活动进行可视化，我们发现缺乏CHD8的幼体在晚上只在中脑的右侧有较高的大脑活动。这导致进一步发现了之前未被报道的大脑同一区域的物理不对称性。在这个项目中，我们现在计划通过确定它是否遵循与其他不对称大脑区域相同的发育规则，在斑马鱼自闭症模型中这种发展可能如何出错，以及这种不对称是否以及如何对睡眠持续时间的调节重要，来研究这种新的不对称性。斑马鱼是研究大脑不对称和睡眠之间联系的一个很好的系统，因为现有的实验工具可以可视化和操纵这两个特性。例如，斑马鱼的突变体和实验操作会导致大脑不对称性的改变，比如具有“双左”、“双右”或“反转”大脑结构的动物。我们计划测试这些操作是否也会导致这一睡眠调节脑区的不对称性发生变化，这将为我们提供重要线索，了解该区域在多大程度上遵循已知的发育规则来创造不对称性。我们还将使用自动视频跟踪斑马鱼在昼夜周期中的变化，看看不对称性的变化是否会影响睡眠持续时间，我们可以通过测量斑马鱼在睡眠状态下保持不活跃的时间来评估这一点。利用遗传学，我们还将用荧光蛋白标记这种中脑不对称性，看看这一区域如何与大脑的其他部分(如已知的睡眠调节中心)连接，观察这一区域选择性表达的分子，并了解在缺乏CHD8的短睡眠动物中，这一区域的形成是如何被破坏的。这些实验将告诉我们更多关于这种不对称的结构和分子性质，并将告知该区域可能是如何调节睡眠的。最后，我们将通过直接控制该区域的活动来测试该非对称区域在睡眠中的作用。例如，我们可以使用激光消融有选择地移除这一区域，并询问该区域是否需要适当的睡眠持续时间。我们还将使用基因干预，将光或药物诱导的蛋白放入这个不对称的区域，这些蛋白可以驱动神经元的兴奋性。这将使我们能够直接控制这一区域的活动，使我们能够测试打开或关闭该区域是否能够改变斑马鱼的睡眠。总而言之，这些实验将让我们对大脑不对称如何调节睡眠时间有一个新的理解，并让我们了解在自闭症等人类疾病中，这种调节可能会如何改变。