The development of children at familial risk for dyslexia: Birth to school age
Annals of Dyslexia
(Impact Factor: 1.48).
12/2004; 54(2):184-220. DOI: 10.1007/s11881-004-0010-3
Children at risk for familial dyslexia (n=107) and their controls (n=93) have been followed from birth to school entry in the Jyväskylä Longitudinal study of Dyslexia (JLD) on developmental
factors linked to reading and dyslexia. At the point of school entry, the majority of the at-risk children displayed decoding
ability that fell at least 1 SD below the mean of the control group. Measures of speech processing were the earliest indices
to show both group differences in infancy and also significant predictive associations with reading acquisition. A number
of measures of language, including phonological and morphological skill collected repeatedly from age three, revealed group
differences and predictive correlations. Both the group differences and the predictive associations to later language and
reading ability strengthened as a function of increasing age. The predictions, however, tend to be stronger and the spectrum
of significant correlations wider in the at-risk group. These results are crucial to early identification and intervention
of dyslexia in at-risk children.
Available from: Kaisa Lohvansuu
- "Heritability and familial clustering of dyslexia has been well established pointing to genetic factors behind dyslexia (Galaburda, 2005; Lyon et al., 2003; Lyytinen et al., 2004; Vellutino et al., 2004). Phonological skills, i.e., ability to recognize and manipulate speech sound elements, is one of the key components for acquiring the ability to read, and deficit in phonological processing is one of the most relevant factors linked to dyslexia (Goswami, 2002; Ramus, 2003; Snowling, 2000; Stanovich, 1988; Torgesen et al., 1997; Vellutino et al., 2004; Wagner and Torgesen, 1987). "
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ABSTRACT: Specific reading disability, dyslexia, is a prevalent and heritable disorder impairing reading acquisition characterized by a phonological deficit. However, the underlying mechanism of how the impaired phonological processing mediates resulting dyslexia or reading disabilities remains still unclear. Using ERPs we studied speech sound processing of 30 dyslexic children with familial risk for dyslexia, 51 typically reading children with familial risk for dyslexia, and 58 typically reading control children. We found enhanced brain responses to shortening of a phonemic length in pseudo-words (/at:a/ vs. /ata/) in dyslexic children with familial risk as compared to other groups. The enhanced brain responses were associated with better performance in behavioral phoneme length discrimination tasks, as well as with better reading and writing accuracy. Source analyses revealed that the brain responses of sub-group of dyslexic children with largest responses originated from a more posterior area of the right temporal cortex as compared to the responses of the other participants. This is the first electrophysiological evidence for a possible compensatory speech perception mechanism in dyslexia. The best readers within the dyslexic group have probably developed alternative strategies which employ compensatory mechanisms substituting their possible earlier deficit in phonological processing and might therefore be able to perform better in phoneme length discrimination and reading and writing accuracy tasks. However, we speculate that for reading fluency compensatory mechanisms are not that easily built and dyslexic children remain slow readers during their adult life.
Available from: Klaus Linkenkaer-Hansen
- "Thus, even though dyslexia manifests in school years, underlying neural anomalies may already be present in the preliterate brain. This is supported by a number of longitudinal studies using auditory event-related potentials (Molfese, 2000; Guttorm et al., 2001; Maurer et al., 2003, 2009; Lyytinen et al., 2004; Van Zuijen et al., 2012, 2013) and visual event-related potentials (Regtvoort et al., 2006; Schulte-Korne and Bruder, 2010; Araujo et al., 2012) reporting differences in brain responses to reading-related stimuli (e.g., speech sounds or visual contrast) between familial risk and control groups, or between control children and children that later become poor readers. "
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ABSTRACT: The hereditary character of dyslexia suggests the presence of putative underlying neural anomalies already in preliterate age. Here, we investigated whether early neurophysiological correlates of future reading difficulties-a hallmark of dyslexia-could be identified in the resting-state EEG of preliterate children. The children in this study were recruited at birth and classified on the basis of parents' performance on reading tests to be at-risk of becoming poor readers (n = 48) or not (n = 14). Eyes-open rest EEG was measured at the age of 3 years, and the at-risk children were divided into fluent readers (n = 24) and non-fluent readers (n = 24) after reading assessment at their third grade of school. We found that fluent readers and non-fluent readers differed in normalized spectral amplitude. Non-fluent readers were characterized by lower amplitude in the delta-1 frequency band (0.5-2 Hz) and higher amplitude in the alpha-1 band (6-8 Hz) in multiple scalp regions compared to control and at-risk fluent readers. Interestingly, across groups these EEG biomarkers correlated with several behavioral test scores measured in the third grade. Specifically, the performance on reading fluency, phonological and orthographic tasks and rapid automatized naming task correlated positively with delta-1 and negatively with alpha-1. Together, our results suggest that combining family-risk status, neurophysiological testing and behavioral test scores in a longitudinal setting may help uncover physiological mechanisms implicated with neurodevelopmental disorders such as the predisposition to reading disabilities.
Available from: Claudia K Friedrich
- "This ability appears to be pivotal for the acquisition of alphabetic writing systems. Children with dyslexia typically have difficulty with detecting or manipulating sounds (e.g., Lyytinen et al., 2004; Ziegler & Goswami, 2005). Once acquired, literacy further shapes phonological awareness. "
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ABSTRACT: Speech is characterized by phonemes and prosody. Neurocognitive evidence supports the separate processing of each type of information. Therefore, one might suggest individual development of both pathways. In this study, we examine literacy acquisition in middle childhood. Children become aware of the phonemes in speech at that time and refine phoneme processing when they acquire an alphabetic writing system. We test whether an enhanced sensitivity to phonemes in middle childhood extends to other aspects of the speech signal, such as prosody. To investigate prosodic processing, we used stress priming. Spoken stressed and unstressed syllables (primes) preceded spoken German words with stress on the first syllable (targets). We orthogonally varied stress overlap and phoneme overlap between the primes and onsets of the targets. Lexical decisions and Event-Related Potentials (ERPs) for the targets were obtained for pre-reading preschoolers, reading pupils and adults. The behavioral and ERP results were largely comparable across all groups. The fastest responses were observed when the first syllable of the target word shared stress and phonemes with the preceding prime. ERP stress priming and ERP phoneme priming started 200 ms after the target word onset. Bilateral ERP stress priming was characterized by enhanced ERP amplitudes for stress overlap. Left-lateralized ERP phoneme priming replicates previously observed reduced ERP amplitudes for phoneme overlap. Groups differed in the strength of the behavioral phoneme priming and in the late ERP phoneme priming effect. The present results show that enhanced phonological processing in middle childhood is restricted to phonemes and does not extend to prosody. These results are indicative of two parallel processing systems for phonemes and prosody that might follow different developmental trajectories in middle childhood as a function of alphabetic literacy.
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