Semantic cognition is thought to involve the interaction of heteromodal conceptual representations with control processes that (i) focus retrieval on currently-relevant information, and (ii) suppress dominant yet irrelevant features and associations. Research suggests that semantic control demands are higher when retrieving a link between weakly-associated word pairs, since there is a mismatch between the pattern of semantic retrieval required by the task and the dominant associations of individual words. In addition, given that heteromodal concepts are thought to reflect the integration of vision, audition, valence and other features, the control demands of semantic tasks should be higher when there is less consistency between these features. In the present study, 62 volunteers completed a semantic decision task, where association strength and semantic-affective congruence were manipulated. We used diffusion tensor magnetic resonance imaging to obtain fractional anisotropy (FA) measures of white matter tracts hypothesized to be part of the semantic network. The behavioural data revealed an interaction between semantic-affective congruence and strength of association, suggesting these manipulations both contribute to semantic control demands. Next we considered how individual differences in these markers of semantic control relate to the microstructure of canonical white matter tracts, complementing previous studies that have largely focused on measures of intrinsic functional connectivity. Repeated-measures analysis of covariance showed opposing interactions between semantic control markers and FA of two tracts: left inferior longitudinal fasciculus (ILF) and right inferior fronto-occipital fasciculus (IFOF). Participants with higher FA in left ILF showed more efficient retrieval of weak associations, and more accurate performance for weak associations when meaning and valence were incongruent, consistent with the hypothesis that this left hemisphere tract supports semantic control. In contrast, participants with higher FA in right IFOF were more accurate for trials in which meaning and valence were congruent, and consequently when semantic control demands were minimised. These findings are consistent with recent studies showing that semantic control processes are strongly left-lateralised. In contrast, long-range connections from vision to semantic regions in the right hemisphere might support relatively automatic patterns of semantic retrieval.

语义认知被认为涉及异质模式概念表示与控制过程的相互作用，该过程（i）将检索集中在当前相关的信息上，并且（ii）压制主要但不相关的特征和关联。研究表明，检索弱关联词对之间的链接时，对语义控制的要求更高，因为任务要求的语义检索模式与单个词的主要关联之间存在不匹配。此外，考虑到异构模式的概念可以反映视觉，听觉，价态和其他功能的集成，因此，当这些功能之间的一致性较低时，对语义任务的控制要求应该更高。在本研究中，有62名志愿者完成了语义决策任务，操纵关联强度和语义情感一致性的地方。我们使用扩散张量磁共振成像来获取假设为语义网络一部分的白质束的分数各向异性（FA）度量。行为数据揭示了语义情感一致性和关联强度之间的相互作用，这表明这些操作都有助于语义控制需求。接下来，我们考虑了这些语义控制标记中的个体差异如何与规范的白质束的微观结构相关联，对以前主要集中于内在功能连接性度量的研究进行了补充。协方差的重复测量分析表明，语义控制标记和两个区域的FA之间存在相反的相互作用：左下纵筋膜（ILF）和右下额枕筋膜（IFOF）。较高的参与者左ILF中的FA显示出更有效的弱关联检索，并且当含义和价位不一致时，弱关联的准确度更高，这与该左半球束支持语义控制的假设相一致。相反，在正确的IFOF中，FA值较高的受试者在含义和效价一致的情况下更准确，因此在语义控制要求最小的情况下。这些发现与最近的研究一致，该研究表明语义控制过程强烈偏左。相反，从视觉到右半球语义区域的远程连接可能支持相对自动的语义检索模式。