Reading acquisition changes our world. Not surprisingly, our brain undergoes significant structural and functional changes throughout reading development that result in a unique reading signature in the brain. These large-scale networks of skilled-adult reading generally encompasses three principal streams. The dorsal stream is predominantly linked to indirect phono- logical reading, i.e., grapheme-phoneme conversion. In contrast, the ventral stream is primarily associated with fast and automatized whole-word recognition. Both streams converge in the frontal stream devoted to a plethora of linguistic operations, for example sophisticated semantic analysis, and various domain-general functions. While the streams are well- researched in adults, their developmental trajectories during reading acquisition are not conclusively examined until today. In the present dissertation, I thus aimed to shed light on the development of the reading net-work from different angles. The overall aim of my dissertation is to advance our understanding of (A) the functioning of the three principal reading streams in literate but not yet adult-like reading children, and (B) the neural prerequisites of future reading acquisition before formal literacy instruction starts. In Liebig et al. (2017), we systematically tested prelexical, orthographic, phonological, and lexico-semantic processing in eight to 13-year-old children to approach the child-reading system. Our results suggest a processing advantage of the ventral and the frontal stream, linked to all central component processes of single word recognition. In contrast, the dorsal stream showed a focal response confined to prelexical and phonological processing. In sum, we observed largely overlapping neural signatures favoring interactive activation in the child- reading network to accomplish written word recognition. In the two further studies of the present dissertation, we examined the neural prerequisites of reading in preliterate kindergarten children. Longitudinally following the same cohort of children, literacy was assessed after two years of structured instruction. In Liebig et al. (2021), we showed that neural response-selectivity to faces, auditory, and spoken words in language and reading streams is sensitive to detect interindividual differences in rapid automatized naming, a critical cognitive-linguistic precursor of literacy. Moreover, the neural response to faces predicted future reading fluency. Most importantly, the neural underpinnings of the observed brain-behavior relationships were detected in the future principle reading streams. The findings thus strongly emphasize that interindividual differences in the reading network mani- fest before reading instruction. In the third empirical study of the present dissertation (Liebig et al., 2020), we used a multifactorial approach and could generalize these interindividual differences to environmental- demographic factors, genotypes, and neurophysiology. In sum, the findings of the present dissertation suggest that interindividual differences in the neural systems for language and reading affect cognitive-linguistic precursors of reading and future literacy acquisition and might thus serve as early biological markers of reading acquisition. Taken together, the key findings of my dissertation foster our knowledge about the neural underpinnings of the central component processes of reading in children. In future research, these could inform computational and neurocognitive models of reading acquisition. The results of the kindergarten children emphasize that interindividual differences in the neural systems strongly involved in reading occur early, i.e., before the onset of reading acquisition and are thus a cause rather than consequence of successful or impeded reading acquisition. Thus, the results of my thesis strongly suggest a much-needed rethinking of reading inter- vention. Based on the new insights of the empirical studies of my dissertation and previous literature, I propose a revised neurodevelopmental account of reading acquisition.
