Howell Amber M, Warrington Shaun, Fonteneau Clara, Cho Youngsun T, Sotiropoulos Stamatios N, Murray John D, Anticevic Alan
Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06511, USA.
Division of Neurocognition, Neurocomputation, & Neurogenetics (N3), Yale University School of Medicine, New Haven, Connecticut, 06511, USA.
bioRxiv. 2023 Oct 10:2023.07.22.550168. doi: 10.1101/2023.07.22.550168.
Each cortical area has a distinct pattern of anatomical connections within the thalamus, a central subcortical structure composed of functionally and structurally distinct nuclei. Previous studies have suggested that certain cortical areas may have more extensive anatomical connections that target multiple thalamic nuclei, which potentially allows them to modulate distributed information flow. However, there is a lack of quantitative investigations into anatomical connectivity patterns within the thalamus. Consequently, it remains unknown if cortical areas exhibit systematic differences in the extent of their anatomical connections within the thalamus. To address this knowledge gap, we used diffusion magnetic resonance imaging (dMRI) to perform brain-wide probabilistic tractography for 828 healthy adults from the Human Connectome Project. We then developed a framework to quantify the spatial extent of each cortical area's anatomical connections within the thalamus. Additionally, we leveraged resting-state functional MRI, cortical myelin, and human neural gene expression data to test if the extent of anatomical connections within the thalamus varied along the cortical hierarchy. Our results revealed two distinct corticothalamic tractography motifs: 1) a sensorimotor cortical motif characterized by focal thalamic connections targeting posterolateral thalamus, associated with fast, feed-forward information flow; and 2) an associative cortical motif characterized by diffuse thalamic connections targeting anteromedial thalamus, associated with slow, feed-back information flow. These findings were consistent across human subjects and were also observed in macaques, indicating cross-species generalizability. Overall, our study demonstrates that sensorimotor and association cortical areas exhibit differences in the spatial extent of their anatomical connections within the thalamus, which may support functionally-distinct cortico-thalamic information flow.
每个皮质区域在丘脑内都有独特的解剖连接模式，丘脑是一个中央皮质下结构，由功能和结构上不同的核团组成。先前的研究表明，某些皮质区域可能具有更广泛的解剖连接，靶向多个丘脑核团，这可能使它们能够调节分布式信息流。然而，目前缺乏对丘脑内解剖连接模式的定量研究。因此，尚不清楚皮质区域在丘脑内的解剖连接范围是否存在系统差异。为了填补这一知识空白，我们使用扩散磁共振成像（dMRI）对来自人类连接体项目的828名健康成年人进行全脑概率性纤维束成像。然后，我们开发了一个框架来量化每个皮质区域在丘脑内的解剖连接的空间范围。此外，我们利用静息态功能磁共振成像、皮质髓鞘和人类神经基因表达数据来测试丘脑内解剖连接的范围是否沿皮质层次结构变化。我们的结果揭示了两种不同的皮质-丘脑纤维束成像模式：1）一种感觉运动皮质模式，其特征是靶向丘脑后外侧的局灶性丘脑连接，与快速的前馈信息流相关；2）一种联合皮质模式，其特征是靶向丘脑前内侧的弥散性丘脑连接，与缓慢的反馈信息流相关。这些发现适用于所有人类受试者，在猕猴中也观察到了，表明具有跨物种普遍性。总体而言，我们的研究表明，感觉运动和联合皮质区域在丘脑内的解剖连接空间范围上存在差异，这可能支持功能上不同的皮质-丘脑信息流。
