The functional role of thalamic-mediated brain networks in memory

丘脑是大脑深处的一个大脑结构，包括多个核，分别是前核、中背核、腹核（进一步分为前核、外侧核和后核）和丘脑枕核。这些结构在记忆检索中的具体贡献以及它们与记忆网络中其他关键结构的交流方式仍未得到充分研究，特别是在人类中。其中一些结构的损伤与记忆障碍有关，这意味着它们应该支持与记忆有关的功能。然而，这种损伤是否破坏了与记忆提取直接相关的过程，或者是否可以用其他认知功能障碍来解释，这是有争议的。同样有争议的是，这些核的损伤是否会阻止患者回忆起他们的记忆，或者是否会影响他们对以前经历过的事情的熟悉感。这些问题在记忆文献中仍然突出的主要原因，与关键的方法学考虑有关，包括参与者人数少——特别是丘脑受损的患者——以及在以前的研究中对认知和记忆的测量不足。在拟议的项目中，我们将选择40名因丘脑中风导致这些结构体积减少而出现记忆问题的患者。最先进的脑成像技术将用于测量这些结构体积，以及纤维束的大小和丘脑核介导的自发连接。将对患者和健康参与者进行认知功能和记忆测试，包括对不同类型刺激（如场景、物体和单词）的熟悉度和回忆测试。健康参与者在进行任务型功能磁共振成像（2个实验）时的功能脑成像也将被用来探索这些结构是否有助于与记忆网络的其他结构交流的记忆检索。这些脑功能测量还将通过同步记录眼球运动来补充，以探索不同的丘脑结构（尤其是腹外侧和枕侧区域）在记忆服务中整合视觉信息的方式。通过将记忆和认知测试与脑成像数据相关联，我们将确定不同的丘脑结构如何在不同类型的记忆中发挥作用，丘脑在记忆中的作用是否可以用其他高级认知功能来解释，以及特定的丘脑核是否负责整合和交流记忆信号。这一发现将从根本上改变人们对丘脑在大脑记忆网络中的作用的描述。

The thalamus, a brain structure deep inside the brain, includes multiple nuclei called anterior, mediodorsal, ventral (further separated into anterior, lateral and posterior) and pulvinar thalamic nuclei. The specific contribution of these structures in memory retrieval and the way they communicate with other critical structures of the memory network remain understudied especially in humans. Damage to some of these structures is linked to memory disorders, which means they should support functions related to memory. However, whether this damage disrupts processes directly related to memory retrieval or can be explained by other cognitive dysfunction is disputed. It is also disputed whether damage in these nuclei prevents patients recollecting their memory or, in addition, it affects their feeling of familiarity for previously experienced things. The main reasons these questions are still outstanding in the memory literature, relate to key methodological considerations, including small number of participants - especially patients with damage in the thalamus - and insufficient measures of cognition and memory in previous studies. In the proposed project, we will select 40 patients with memory problems as a result of thalamic stroke resulting in reduced volumes in these structures. State-of-the-art brain imaging will be used to measure these structural volumes, as well as the size of fibre tracts and spontaneous connectivity mediated by the thalamic nuclei. Tests of cognitive function and memory, including tests of familiarity and recollection for different types of stimuli, such as scenes, objects and words, will be given to patients and healthy participants. Functional brain imaging in healthy participants, while undergoing task-based fMRI (2 experiments) will also be used to explore whether these structures contribute to memory retrieval in communication with other structures of the memory network. These functional brain measures will be also complemented by synchronised recording of eye movements to explore the way the various thalamic structures (and especially the ventrolateral and pulvinar areas) integrate visual information in the service of memory. By relating memory and cognitive tests with brain imaging data, we will determine how the various thalamic structures function in the different types of memory, whether the role of the thalamus in memory can be explained by other higher cognitive functions and whether specific thalamic nuclei are responsible for integrating and communicating memory signals. The findings will fundamentally change the way the role of the thalamus is described within the brain's memory networks.