Neuropsychologia 141 (2020) 107438 Available online 18 March 2020 0028-3932/© 2020 Elsevier Ltd. All rights reserved. Linking individual differences in semantic cognition to white matter microstructure Juli� an Marino D� avolos, PhD a, * , Juan Cruz Arias b , Elizabeth Jefferies, PhD a a Department of Psychology and York Neuroimaging Centre, University of York, YO10 5DD, York, UK b Instituto de Investigaci� on Oulton, C� ordoba, C� ordoba, Argentina A R T I C L E INFO Keywords: Semantic control Diffusion tensor magnetic resonance imaging White matter microstructure Fractional anisotropy ABSTRACT 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 refect the integration of vision, audition, valence and other features, the control de- mands 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 behav- ioural data revealed an interaction between semantic-affective congruence and strength of association, sug- gesting 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 effcient 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 fndings 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. 1. Introduction Our store of conceptual knowledge contains many features and as- sociations, many of which are not relevant at a given moment, and we can fexibly shape retrieval to focus on specifc non-dominant properties as required by the circumstances. For example, we know that newspa- pers are for reading, but when selecting an object to swat a fy, prop- erties such as being rollable and lightweight come to the fore. This capacity for fexible semantic cognition involves the interaction of conceptual representations with control processes (Davey et al., 2016; Jefferies, 2013; Lambon Ralph et al., 2016), and consequently all se- mantic tasks (including the one used in the current study) are thought to engage these two neurocognitive components (although to varying degrees). Contemporary theoretical approaches such as the ‘Hub and Spokes’ model suggest that conceptual representations arise from the integration of multiple types of features, such as visual, auditory, motor, verbal, spatial and emotional, within ventral aspects of the anterior temporal lobes (ATL; e.g., Patterson et al., 2007). Consequently, the same heter- omodal conceptual representations – interacting with relevant unimodal * Corresponding author. Yamanas 45, U9210, Puerto Madryn, Chubut, Argentina. E-mail addresses: juliancarlosmarino.davolos@york.ac.uk (J. Marino D� avolos), juan.cruz.arias.11@gmail.com (J.C. Arias), beth.jefferies@york.ac.uk (E. Jefferies). Contents lists available at ScienceDirect Neuropsychologia journal homepage: http://www.elsevier.com/locate/neuropsychologia https://doi.org/10.1016/j.neuropsychologia.2020.107438 Received 3 August 2019; Received in revised form 28 February 2020; Accepted 10 March 2020