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Brain imaging results illustrative of the search for neuronal markers of dyslexia are reviewed. Event-related potentials (ERPs) are shown to be effective indices of auditory processes involved in speech perception and thus, apparently also helpful in uncovering the neuronal basis of language problems associated with difficulties in reading. Results from the authors' laboratory show that, even at a very early age, brain responses (ERPs) to speech sounds can differentiate children with and without risk for dyslexia and also show reliable predictive correlations to later language development and reading acquisition. The review also covers dyslexia research in which other brain imaging techniques have been applied. The most recent imaging studies have opened interesting views to functional changes associated the remediation of reading problems. [ABSTRACT FROM AUTHOR]

Abstract: This study aimed at determining whether an intervention game developed for strengthening phonological awareness has a remediating effect on reading skills and central auditory processing in 6-year-old preschool children with difficulties in reading-related skills. After a 3-hour training only, these children made a greater progress in reading-related skills than did their matched controls who did mathematical exercises following comparable training format. Furthermore, the results suggest that this brief intervention might be beneficial in modulating the neural basis of phonetic discrimination as an enhanced speech-elicited mismatch negativity (MMN) was seen in the intervention group, indicating improved cortical discrimination accuracy. Moreover, the amplitude increase of the vowel-elicited MMN significantly correlated with the improvement in some of the reading-skill related test scores. The results, albeit obtained with a relatively small sample, are encouraging, suggesting that reading-related skills can be improved even by a very short intervention and that the training effects are reflected in brain activity. However, studies with larger samples and different subgroups of children are needed to confirm the present results and to determine how children with different dyslexia subtypes benefit from the intervention. [Copyright &y& Elsevier]

Abstract: This study examined the role of motivational or attitudinal factors, such as achievement beliefs and behaviours, in learning to read before receiving formal instruction. A total of 200 Finnish children were examined at ages 5 and 6½. Half of them (n =107) had a familial risk for dyslexia. The results showed that those children who were verbally skilful at age 5 showed a higher level of task-focused behaviour at age 6½. This task-focused behaviour then contributed to spontaneous reading acquisition. The impact of previous verbal skills on spontaneous reading acquisition was mediated in part by achievement behaviour. [Copyright &y& Elsevier]

Dyslexia is a neurobiological disorder impairing learning to read. Brain responses of infants at genetic risk for dyslexia are abnormal already at birth, and associations from infant speech perception to preschool cognitive skills and reading in early school years have been documented, but there are no studies showing predicting power until adolescence. Here we show that in at-risk infants, brain activation to pseudowords at left hemisphere predicts 44% of reading speed at 14 years, and even improves the prediction after taking into account neurocognitive preschool measures of letter naming, phonology, and verbal short-term memory. The association between infant brain responses and reading speed is mediated by preschool rapid automatized naming ability. Therefore, we suggest that rapid naming and reading speed could share a similar cognitive process of automatized access to lexicon via phonological representations, and brain activation to speech sounds in infancy probably acts as an index of deficient development of the same process. [ABSTRACT FROM AUTHOR]

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 phonemic length discrimination task, 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 phonemic 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. [ABSTRACT FROM AUTHOR]

Abstract: Dyslexia is characterized by deficits in phonological processing abilities. However, it is unclear what the underlying factors for poor phonological abilities or speech sound representations are. One hypothesis suggests that individuals with dyslexia have problems in basic acoustic perception which in turn can also cause problems in speech perception. Here basic auditory processing was assessed by auditory event-related potentials recorded for paired tones presented in an oddball paradigm in 9-year-old children with dyslexia and a familial background of dyslexia, typically reading children at familial risk for dyslexia and control children without risk for dyslexia. The tone pairs elicited a P1–N250 complex with emerging N1–P2 complex. Control children showed larger responses over the left-than-right hemisphere at the P1 and P2 time windows for both short and long within-pair intervals (WPI; 10 and 255ms) whereas children with dyslexia showed this pattern only for the tone pairs with the long WPI. The response for the pairs with the short WPI showed equal amplitudes over both hemispheres in children with dyslexia. The findings indicate that individuals with dyslexia process basic auditory information differently when the tones are within the temporal window of integration. [Copyright &y& Elsevier]