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Abstract

Congenitally blind individuals have been shown to activate the visual cortex during non-visual tasks. The


neuronal mechanisms of such cross-modal activation are not fully understood. Here, we used an auditory working


memory training paradigm in congenitally blind and in sighted adults. We hypothesized that the visual cortex gets


integrated into auditory working memory networks, after these networks have been challenged by training. The


spectral profile of functional networks was investigated which mediate cross-modal reorganization following


visual deprivation. A training induced integration of visual cortex into task-related networks in congenitally blind


individuals was expected to result in changes in long-range functional connectivity in the theta-, beta- and gamma


band (imaginary coherency) between visual cortex and working memory networks. Magnetoencephalographic


data were recorded in congenitally blind and sighted individuals during resting state as well as during a voicebased


working memory task; the task was performed before and after working memory training with either


auditory or tactile stimuli, or a control condition. Auditory working memory training strengthened theta-band


(2.5–5 Hz) connectivity in the sighted and beta-band (17.5–22.5 Hz) connectivity in the blind. In sighted participants,


theta-band connectivity increased between brain areas typically involved in auditory working memory


(inferior frontal, superior temporal, insular cortex). In blind participants, beta-band networks largely emerged


during the training, and connectivity increased between brain areas involved in auditory working memory and as


predicted, the visual cortex. Our findings highlight long-range connectivity as a key mechanism of functional


reorganization following congenital blindness, and provide new insights into the spectral characteristics of


functional network connectivity.