TIME - GLUING CROSS-MODAL MEMORIES VIA SYNCHRONISATION

当我们回忆过去的事件时，我们常常发现这些事件是多感官的。例如，当你想到你最喜欢的露营假期时，你可能会想起篝火闪烁的光芒和燃烧时木头的噼啪声。这一提议解决了一个基本问题，即是什么机制将所有这些不同的元素结合在一起，使我们能够拥有这些整合记忆。这个问题不是微不足道的，因为几十年的大脑研究告诉我们，多感官刺激的不同方面在不同的大脑区域被处理。我们的大脑可能会使用一种机制来连接构成记忆的不同元素，这种机制与人类大脑活动的丰富节律性有关。具体来说，神经元群的放电是同步的，而不是混乱的。这些节律使神经元能够协同处理传入的信息，并在大脑的不同部分进行处理。此外，在动物身上进行的神经科学研究表明，这种同步活动更有可能导致神经元之间连接的改变，而神经元是所有记忆的“硬件”。因此，同步是将短暂体验转化为记忆的关键机制，这似乎是唯一合乎逻辑的。然而，令人惊讶的是，同步在建立记忆中的基本作用的证据很少。该项目利用了申请者最近的一项发现，首次揭示了神经同步在多感觉记忆中的关键作用。使用一种新颖的方法，通过有节奏的感觉刺激（例如，闪烁的视频/声音）来控制大脑听觉和视觉区域之间的同步，申请者证明，当两种模式同步时，与不同步时相比，多感觉刺激更容易被记住。我们把这种效应称为时间诱导记忆效应（TIME）。这项研究的目的是建立在这些令人兴奋的初步发现的基础上，并提供一系列关于时间在不同条件下如何影响人类记忆的经验行为和神经数据。为此，提出了五个工作包，其中将使用一个实验的变体，其中以不同的频率调制3-s声音剪辑的音量和3-s视频剪辑的亮度。动物研究预测，TIME应该只在特定的大脑节奏下起作用，即较慢的4赫兹节奏和较快的40赫兹节奏。将在第一个工作包中测试的预测。第二个工作包解决了一个令人兴奋的问题，即刺激的同步呈现是否会使记忆性能超出其自然极限。这一结果可能对改善健康和非健康人群的记忆力具有重要意义。第三个工作包测试一个重要的边界条件，即是否需要注意才能获得时间。在第四个工作包中，我们将揭示时间对记忆产生影响的大脑区域。在最后的第五个工作包中，我们将测试是否有可能通过对右手食指进行有节奏的刺激来提高视听记忆关联的能力。这个实验具有很强的转化潜力，因为它可以激发廉价刺激设备的开发，以提高健康学生、老年人或患者的记忆力。总之，这一提议验证了一个相对简单但优雅的观点，即对包含不同元素的事件形成记忆的能力首先取决于处理这些元素的大脑区域的同步。因此，使用一种创新的新开发方法，该项目可以阐明将我们的记忆结合在一起的关键组成部分，即同步。

When we remember past events we often find that these events are multisensory. For instance, when you think about your favourite camping holiday, you might recall the flickering light of the campfire and the crackle of the wood as it burned. This proposal addresses the fundamental question of what the mechanism is that holds all these different elements together so that we can have these integrated memories. This question is not trivial given that decades of brain research has taught us that different aspects of a multisensory stimulus are processed in different brain regions. A possible mechanism that our brains might use to link the different elements that make up a memory has to do with the abundant rhythmicity of human brain activity. Specifically, groups of neurons discharge synchronously, rather than chaotically. These rhythms allow neurons to engage in collaborative processing of incoming information, processed in different parts of the brain. Furthermore, neuroscience studies in animals showed that such synchronised activity is more likely to result in modifications of connections between neurons, which is the "hardware" underlying all memories. It therefore appears only logical that synchronisation is the key mechanism that turns a transient experience into a memory. Surprisingly, however, evidence for this fundamental role of synchronisation in building memories is scarce. This project capitalises on a recent discovery that was made by the applicants shedding a first light onto the critical role of neural synchronisation for multisensory memories. Using a novel way of controlling the synchronisation between auditory and visual brain regions via rhythmic sensory stimulation (i.e. a flickering video/sound) the applicants demonstrated that a multisensory stimulus is more likely to be remembered when the two modalities were synchronised compared to when they were not synchronised. We refer to this effect as the Timing Induced Memory Effect (TIME). The aim of this research is to build on these initial exciting findings and to provide a range of empirical behavioural and neural data on how TIME impacts on human memory under different conditions. To this end, five work packages are proposed which will use variants of an experiment where the volume of a 3-s sound clip and the luminance of a 3-s video clip are modulated at different frequencies. Animal studies predict that TIME should only work at particular brain rhythms, i.e. a slower 4 Hz rhythm and a faster 40 Hz rhythm. A prediction that will be tested in the first work package. The second work package addresses the exciting question of whether synchronised presentation of stimuli increases memory performance beyond its natural limits. This result could have strong implications for improving memory in healthy and non-healthy populations. A third work package tests an important boundary condition, namely whether attention is required to obtain TIME. In a fourth work package we will unravel the brain regions at which TIME exerts its effects on memory. In a final fifth work package we will test whether it is possible to boost the capacity for audio-visual memory associations by delivering rhythmic stimulation to the right index finger. This experiment, has a strong translational potential as it could spark the development of cheap stimulation devices to improve memory in healthy students, older adults, or patients.Together, this proposal tests the relatively simple but elegant idea that the ability to form memories for events which contain different elements depends on the synchronisation of the brain regions processing these elements in the first place. Using an innovative newly developed approach this project could therefore illuminate the critical component that holds our memories together, i.e. synchronisation.