Eze Princess, Omorotionmwan Efrem, Cummine Jacqueline
Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB T6A 2G4, Canada;
Communication Sciences and Disorders, University of Alberta, Edmonton, AB T6A2 G4, Canada.
NeuroSci. 2024 Jan 2;5(1):39-58. doi: 10.3390/neurosci5010003. eCollection 2024 Mar.
Evidence has been provided for a clear structural distinction between the dorsal and ventral portions of the inferior frontal occipital fasciculus (IFOF). As such, there is reason to propose that there might also be a functional differentiation of the dorsal and ventral components of the IFOF. Here, we explored three main hypotheses/schools of thought with regards to the functional frameworks of the dorsal and ventral components of the IFOF: (1) the phonological vs. semantic processing hypothesis, (2) the difficult vs. non-difficult task processing hypothesis and (3) the automatic vs. non-automatic processing hypothesis. Methods: Participants (N = 32) completed a series of behavioral tasks that aligned with each of the main hypotheses. Using a regression-based approach, we assessed the unique contribution of behavioral performance to dorsal and ventral IFOF white matter indicators (i.e., fractional anisotropy and mean diffusivity). Results: We found significant relationships between ventral IFOF indices and orthographic awareness ( = 0.018) and accuracy ( = 0.009). Overall, our results provide converging evidence that the IFOF primarily operates as a ventral language tract in adults. Thus, the structural distinction between dorsal and ventral IFOF does not manifest as a parallel functional distinction.
已有证据表明，额枕下束（IFOF）的背侧和腹侧部分在结构上存在明显差异。因此，有理由推测IFOF的背侧和腹侧成分在功能上也可能存在差异。在此，我们探讨了关于IFOF背侧和腹侧成分功能框架的三种主要假设/思想流派：（1）语音加工与语义加工假设，（2）困难任务与非困难任务加工假设，以及（3）自动加工与非自动加工假设。方法：参与者（N = 32）完成了一系列与各主要假设相符的行为任务。我们采用基于回归的方法，评估了行为表现对背侧和腹侧IFOF白质指标（即分数各向异性和平均扩散率）的独特贡献。结果：我们发现腹侧IFOF指标与正字法意识（ = 0.018）和准确性（ = 0.009）之间存在显著关系。总体而言，我们的结果提供了趋同证据，表明IFOF在成年人中主要作为一条腹侧语言束发挥作用。因此，IFOF背侧和腹侧之间的结构差异并未表现为平行的功能差异。
