Previous Diffusion Tensor Imaging (DTI) studies in children suggest that developmental improvements in inhibitory control is largely mediated by the degree of white matter organisation within a right-lateralised network of fronto-basal-ganglia regions. Recent advances in diffusion imaging analysis now permit greater biological specificity, both in identifying specific fibre populations within a voxel, as well as in the underlying microstructural properties of that white matter. In the present work, employing a novel fixel-based analysis (FBA) framework, we aimed to comprehensively investigate microstructure within the fronto-basal-ganglia circuit in childhood, and its contribution to inhibition performance. Diffusion MRI data were obtained from 43 healthy children and adolescents aged 9–11 years (10.42 ± .41 years, 18 females). Response inhibition for each participant was assessed using the Stop-signal Task (SST) and quantified as a Stop–Signal Reaction Time (SSRT). All steps relevant to FBA were implemented in MRtrix3Tissue, a fork of the MRtrix3 software library. The fronto-basal-ganglia circuit were delineated using probabilistic tractography to identify the tracts connecting the subthalamic nucleus, pre-supplementary motor area and the inferior frontal gyrus. Connectivity-based fixel enhancement (CFE) was then used to assess the association between fibre density (FD) and fibre cross-section (FC) with inhibitory ability. Significant negative associations were identified for FD in both the right and left fronto-basal-ganglia circuit whereby greater FD was associated with better inhibition performance (e.g., reduced SSRTs). This effect was specifically localised to clusters of fixels within white matter proximal to the right subthalamic nucleus. We did not report any meaningful associations between SSRT and FC. Whilst findings are broadly consistent with prior DTI evidence, current results suggest that SSRT is predominantly facilitated by subcortical microstructure of the connections projecting from the subthalamic nucleus to the cortical regions of the network. Our findings extend current understanding of the role of white matter in childhood response inhibition.

先前对儿童进行的弥散张量成像 (DTI) 研究表明，抑制控制的发育改善在很大程度上是由额基底神经节区域右侧网络内白质组织的程度所介导的。扩散成像分析的最新进展现在允许更大的生物学特异性，既可以识别体素内的特定纤维群，也可以识别该白质的潜在微观结构特性。在目前的工作中，我们采用新的基于固定素的分析 (FBA) 框架，旨在全面研究儿童额基底神经节回路中的微观结构及其对抑制性能的贡献。弥散 MRI 数据来自 43 名 9-11 岁的健康儿童和青少年（10.42 ± .41 岁，18 名女性）。使用停止信号任务 (SST) 评估每个参与者的反应抑制，并量化为停止信号反应时间 (SSRT)。与 FBA 相关的所有步骤都在 MRtrix3Tissue（MRtrix3 软件库的一个分支）中实现。额基底神经节回路使用概率束成像来确定连接丘脑底核、前辅助运动区和额下回的束。然后使用基于连接的固定素增强 (CFE) 来评估纤维密度 (FD) 和纤维横截面 (FC) 之间的关联与抑制能力。在右侧和左侧额基底神经节回路中，FD 与 FD 显着负相关，其中更大的 FD 与更好的抑制性能（例如，减少的 SSRT）相关。这种效应特别局限于右丘脑底核附近的白质内的固定点簇。我们没有报告 SSRT 和 FC 之间的任何有意义的关联。虽然研究结果与先前的 DTI 证据大致一致，但目前的结果表明，SSRT 主要是由从丘脑底核突出到网络皮质区域的连接的皮质下微结构促进的。我们的发现扩展了目前对白质在儿童反应抑制中的作用的理解。目前的结果表明 SSRT 主要是由从丘脑底核突出到网络皮质区域的连接的皮质下微结构促进的。我们的发现扩展了目前对白质在儿童反应抑制中的作用的理解。目前的结果表明 SSRT 主要是由从丘脑底核突出到网络皮质区域的连接的皮质下微结构促进的。我们的发现扩展了目前对白质在儿童反应抑制中的作用的理解。