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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 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]

Abstract: This study addresses how to validate the rationale of group component analysis (CA) for blind source separation through estimating the number of sources in each individual EEG dataset via model order selection. Control children, typically reading children with risk for reading disability (RD), and children with RD participated in the experiment. Passive oddball paradigm was used for eliciting mismatch negativity during EEG data collection. Data were cleaned by two digital filters with pass bands of 1–30Hz and 1–15Hz and a wavelet filter with the pass band narrower than 1–12Hz. Three model order selection methods were used to estimate the number of sources in each filtered EEG dataset. Under the filter with the pass band of 1–30Hz, the numbers of sources were very similar among different individual EEG datasets and the group ICA would be suggested; regarding the other two filters with much narrower pass bands, the numbers of sources were relatively diverse, and then, applying group ICA would not be appropriate. Hence, before group ICA is performed, its rationale can be logically validated by the estimated number of sources in EEG data through model order selection. [Copyright &y& Elsevier]

Abstract: According to several studies auditory discrimination as measured by mismatch negativity (MMN) is compromised in participants with reading disorder. However, studies on duration discrimination have produced conflicting findings [Baldeweg, T., Richardson, A., Watkins, S., Foale, C., & Gruzelier, J., 1999. Impaired auditory frequency discrimination in dyslexia detected with mismatch evoked potentials. Annals of Neurology, 4, 1–9; Corbera, S., Escera, C., & Artigas, J., 2006. Impaired duration mismatch negativity in developmental dyslexia. Neuroreport, 17, 1051–1055]. Auditory sensitivity has not been as actively investigated among children with attention deficit, although attention problems often co-occur with dyslexia. The present study is a reanalysis of MMN data gathered from control children and children with reading disorder (RD) and/or attention deficit (AD). In our previous analysis [Huttunen, T., Halonen, A., Kaartinen, J. & Lyytinen, H., 2007. Does mismatch negativity show differences in reading disabled children as compared to normal children and children with attention deficit? Developmental Neuropsychology, 31, 453–470.], the only significant difference between the groups was in the lateralization of the MMNs in the RD and the control group: the MMNs of the RD group were more pronounced over the left hemisphere, while those of the control group appeared larger over the right hemisphere. A reanalysis was conducted to study whether the group definition criteria and/or overlap of the attention and reading deficits in the AD group might have affected the results. For this purpose participants were divided to four groups: control children, children with RD, children with AD, and children with both RD and AD. MMN was elicited by duration deviations in a continuous sound. Significant differences were observed in the MMN peaks between the control group and all clinical groups: the MMNs were diminished in the right hemisphere in the RD group, in all frontal and central channels in the RD+AD group, and the MMN peaks appeared earlier in frontal channels in the AD group. [Copyright &y& Elsevier]