br Methods br Results br Discussion

Methods
Results
Discussion
Conclusions According to our knowledge, this purchase KB-R7943 mesylate is the first study that investigates directed connectivity during word reading in 9-year old typically reading and dyslexic children with different levels of reading dysfluency. Our results point to different patterns of connectivity in the reading network of typical and dyslexic children and within dyslexic children as a function of the severity of their reading dysfluency. Specifically, moderately dysfluent dyslexics, who previously showed a less severe impairment in letter-speech sound coupling (Žarić et al., 2014), now showed an impairment in the left posterior network for visual word processing, but did not show disrupted connectivity during the processing of letter-like false fonts. Severely dysfluent dyslexics, who previously showed a lack of firm associations between letters and speech sounds (Žarić et al., 2014), now revealed a (1) disruption of connectivity in the left posterior network for visual word processing, (2) compensatory involvement of anterior and right hemisphere sites, and (3) a lack of electrophysiological differentiation between words and letter-like stimuli. Finally, severely dysfluent dyslexics differed in connectivity from moderately dysfluent dyslexics in the false font condition. The finding that the functional connectivity pattern in dyslexic children is related to their reading level, may in part explain the mixed results obtained in previous functional connectivity studies of dyslexia.
Acknowledgments Unfortunately, our co-author, Professor Leo Blomert, passed away on November 25, 2012. His contributions to the project prior to this date were significant. This project, “Fluent reading acquisition neurocognitively decomposed: the case of dyslexia (HCMI 10–59)”, is funded by the National Initiative Brain and Cognition (NIHC), a part of the Netherlands Organization for Scientific Research (NWO) under grant number 056-14-015. We would like to thank Suzanne van Grieken, Marlena van Langevelde, Gert-Jan Munneke, Jitka Annen, Mandy Meijer, Helene Vos and Jorinde Wesseling for their help during data collection. Finally, we would like to express our gratitude to the children participating in the research and to their parents.
Introduction Successful literacy crucially depends on intact phonological processing. In learning to read and write children need to be aware of the sounds of their native language, created from segmental phonemes as the smallest sound elements, as well as the prosody of suprasegmental words and phrases (Bryant and Goswami, 1987). At the segmental level, for example, listeners need to carefully discriminate phonemic details of vowels and consonants to fathom the intended meaning of utterances (e.g., wet cat versus vet cat). In spelling, the written coding of phonemes follows language-specific rules and is more challenging in languages with less consistent phoneme-grapheme correspondences (Ziegler et al., 2010; Ziegler and Goswami, 2006). In the reverse grapheme-to-phoneme mapping, that is reading, phonemic awareness is particularly relevant for beginning readers, who decipher words sound by sound (Coltheart et al., 2001; Ziegler et al., 2000). Taken together, the ability to successfully detect and manipulate phonemes (i.e., phonemic awareness) is essential in both spelling and reading acquisition and has been reported as predictor of literacy outcome across languages (Caravolas et al., 2013; Moll et al., 2014; Seymour et al., 2003; Ziegler et al., 2010). Phonemic awareness has not only been found to explain individual differences in reading and spelling, but also to differentiate typical and literacy-impaired populations, as in developmental dyslexia (DD) (World Health Organization, 2009). The idea of intact phonological processing, specifically phonemic awareness, as essential precursor of successful literacy acquisition is rooted in the phonological deficit theory of DD (Ramus et al., 2003; Snowling, 2000). While already newborns are able to discriminate different phonemes (Cheour-Luhtanen et al., 1995; Kushnerenko et al., 2001), infants at familial risk of developing DD were found to show impaired discrimination of vowel and consonant lengths (Leppänen et al., 2002; Pihko et al., 1999). Moreover, longitudinal studies have attested a direct relation between infants’ phonemic abilities and later literacy skills (Schaadt et al., 2015; van Zuijen et al., 2013). Also, school children and adults with DD were found to perform significantly worse on phoneme discrimination tasks than their unaffected peers (Groth et al., 2011; Hämäläinen et al., 2009; Landerl, 2003; Steinbrink et al., 2014). Thus, there is a substantial line of research on the, potentially causal, relationship between the perception of segmental phonology and literacy impairments (see also, Goswami, 2015).