Department of Neurology, University of California San Francisco, San Francisco, California, United States of America.
Department of Neurology, University of California San Francisco, San Francisco, California, United States of America; Joint Graduate Group in Bioengineering, University of California San Francisco and University of California Berkeley, San Francisco/Berkeley, California, United States of America.
PLoS One. 2014 Jun 19;9(6):e100274. doi: 10.1371/journal.pone.0100274. eCollection 2014.
The inferior fronto-occipital fasciculus (IFOF) is historically described as the longest associative bundle in the human brain and it connects various parts of the occipital cortex, temporo-basal area and the superior parietal lobule to the frontal lobe through the external/extreme capsule complex. The exact functional role and the detailed anatomical definition of the IFOF are still under debate within the scientific community. In this study we present a fiber tracking dissection of the right and left IFOF by using a q-ball residual-bootstrap reconstruction of High-Angular Resolution Diffusion Imaging (HARDI) data sets in 20 healthy subjects. By defining a single seed region of interest on the coronal fractional anisotropy (FA) color map of each subject, we investigated all the pathways connecting the parietal, occipital and posterior temporal cortices to the frontal lobe through the external/extreme capsule. In line with recent post-mortem dissection studies we found more extended anterior-posterior association connections than the "classical" fronto-occipital representation of the IFOF. In particular the pathways we evidenced showed: a) diffuse projections in the frontal lobe, b) fronto-parietal lobes connections trough the external capsule in almost all the subjects and c) widespread connections in the posterior regions. Our study represents the first consistent in vivo demonstration across a large group of individuals of these novel anterior and posterior terminations of the IFOF detailed described only by post-mortem anatomical dissection. Furthermore our work establishes the feasibility of consistent in vivo mapping of this architecture with independent in vivo methodologies. In conclusion q-ball tractography dissection supports a more complex definition of IFOF, which includes several subcomponents likely underlying specific function.
下额枕束（IFOF）在历史上被描述为人类大脑中最长的联合束，它通过外囊/极囊复合体将枕叶皮质、颞底区和上顶叶与额叶连接起来。IFOF 的确切功能作用和详细解剖定义在科学界仍存在争议。在这项研究中，我们通过对 20 名健康受试者的高角度分辨率弥散成像（HARDI）数据集进行 q 球残余引导重建，对右侧和左侧 IFOF 进行了纤维追踪解剖。通过在每个受试者的冠状面各向异性分数（FA）彩色图上定义单个种子感兴趣区，我们研究了连接顶叶、枕叶和后颞叶与额叶的所有通路。与最近的死后解剖研究一致，我们发现了比 IFOF 的“经典”额枕代表更广泛的前后关联连接。特别是，我们证实的途径包括：a）在额叶中的弥散投射，b）在外囊中的额顶叶连接，几乎在所有受试者中都存在，c）在后部的广泛连接。我们的研究代表了第一个一致的活体证明，即在一大群个体中，详细描述了这些 IFOF 的新的前、后端终止，而这些仅通过死后解剖学解剖来描述。此外，我们的工作建立了用独立的活体方法一致地对这种结构进行活体映射的可行性。总之，q 球轨迹解剖支持 IFOF 的更复杂定义，它包括几个亚成分，可能潜在地支持特定的功能。
