Contents lists available at Neuropsychologia ELSEVIER journal homepage:www.elsevier.com/locate/neuropsychologia Reorganization of large-scale brain networks in deaf signing adults:The role of auditory cortex in functional reorganization following deafness Josefine Andin,Emil Holmer. ARTICLE INFO ABSTRACT vity for deaf supp nge as a central 1.Introduction Cortical areas that are deprived of input during development cortical )Thus,individuals who are e current c is likely to repre d,20 sing the sen s lost.Thes e changes a am to individualswithno ation differs betw nput in blind individuals is ass ted with rec ment of the visua e and ized by of山 interventions and bilingual schooling with sign language as the m remaining senses,i.e.,in the superior temporal cortex (Stevens and 028392/e202m0X202 s.Published by Elsevier Ltd.This is an open access article under the CC BY license (http://crear org/licemses/by/4.0/). Neuropsychologia 166 (2022) 108139 Available online 4 January 2022 0028-3932/© 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Reorganization of large-scale brain networks in deaf signing adults: The role of auditory cortex in functional reorganization following deafness Josefine Andin a,* , Emil Holmer a,b a Linnaeus Centre HEAD, Department of Behavioural Sciences and Learning, Linkoping ¨ University, SE, 581 83, Link¨ oping, Sweden b Center for Medical Image Science and Visualization, Link¨ oping University, Sweden ARTICLE INFO Keywords: Deaf signers Deafness Large-scale brain networks ICA Functional connectivity Superior temporal cortex ABSTRACT If the brain is deprived of input from one or more senses during development, functional and structural reor￾ganization of the deprived regions takes place. However, little is known about how sensory deprivation affects large-scale brain networks. In the present study, we use data-driven independent component analysis (ICA) to characterize large-scale brain networks in 15 deaf early signers and 24 hearing non-signers based on resting-state functional MRI data. We found differences between the groups in independent components representing the left lateralized control network, the default network, the ventral somatomotor network, and the attention network. In addition, we showed stronger functional connectivity for deaf compared to hearing individuals from the middle and superior temporal cortices to the cingulate cortex, insular cortex, cuneus and precuneus, supra￾marginal gyrus, supplementary motor area, and cerebellum crus 1, and stronger connectivity for hearing non￾signers to hippocampus, middle and superior frontal gyri, pre- and postcentral gyri, and cerebellum crus 8. These results show that deafness induces large-scale network reorganization, with the middle/superior temporal cortex as a central node of plasticity. Cross-modal reorganization may be associated with behavioral adaptations to the environment, including superior ability in some visual functions such as visual working memory and visual attention, in deaf signers. 1. Introduction Cortical areas that are deprived of sensory input during development reorganize to respond to the preserved senses (Bavelier and Neville, 2002; Merabet and Pascual-Leone, 2010). Thus, individuals who are deprived of sensory input in one modality, due to e.g., deafness or blindness, hold an important clue to understanding brain reorganiza￾tion. Early deafness has repeatedly been associated with reorganization of the auditory cortex (Cardin et al., 2018; Emmorey et al., 2011; Karns et al., 2012; Malaia et al., 2014), but there is also some evidence of reorganization beyond this region (Bonna et al., 2020; Li et al., 2016). In the present study, we apply a data-driven approach, i.e., independent component analysis (ICA) on resting-state fMRI data, to further our understanding of how network organization differs between deaf and hearing individuals. This will in turn have implications for how findings from functional connectivity studies that investigate network nodes can be interpreted. The focus of this study is on an adult deaf population for whom sign language learning has been optimized by early sign language interventions and bilingual schooling with sign language as the main mode of communication (Bagga-Gupta, 2004; Meristo et al., 2007). The combination of fluent language skills and lack of auditory input makes deaf signers a highly valuable study population for investigating cortical reorganization due to sensory deprivation. However, with the intro￾duction of cochlear implants in almost every deaf infant in the Western world, including Sweden where this study is situated, the current cohort is likely to represent one of the last cohorts of its kind. The lack of sensory input induces changes in brain regions associated with the processing of the remaining senses, as well as in the region typically used for processing the sense that is lost. These changes are associated with behavioral adaptations, and sometimes even superior skills compared to individuals with no sensory impairment (for a review see Merabet and Pascual-Leone, 2010). For example, the lack of visual input in blind individuals is associated with recruitment of the visual cortex, i.e., the sensory-deprived area, for tactile Braille reading (Reich et al., 2011), sound localization (Gougoux et al., 2005), and verbal processing (Amedi et al., 2004). Superior processing of auditory stimuli has further been associated with altered processing in areas of the remaining senses, i.e., in the superior temporal cortex (Stevens and * Corresponding author. Linkopings ¨ universitet, IBL, I-huset, SE, 581 83, Linkoping, ¨ Sweden. E-mail addresses: josefine.andin@liu.se (J. Andin), emil.holmer@liu.se (E. Holmer). Contents lists available at ScienceDirect Neuropsychologia journal homepage: www.elsevier.com/locate/neuropsychologia https://doi.org/10.1016/j.neuropsychologia.2021.108139 Received 30 June 2021; Received in revised form 17 December 2021; Accepted 31 December 2021