Search

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: Objective: To design a fast algorithm that evaluates the degree of correlation of recordings among single trials (CoRaST) for mismatch negativity (MMN) activity. Methods: The participants were 114 children, aged 8–16years. MMNs were elicited by two deviants in duration that occurred in an uninterrupted sound within a passive oddball paradigm, and each trial lasted 650ms with 130 samples. CoRaST was derived from the frequency-domain MMN model through Fourier transformation. To validate the effectiveness of the proposed method, the wavelet transformation-based inter-trial coherence (ITC) was taken as a reference. Results: Performances of the proposed CoRaST and ITC were similar in evaluating the correlation of MMN activity among single trials. However, the analysis of electroencephalograph (EEG) recordings comprising approximately 330 trials at one channel took approximately 0.12s with CoRaST, whereas ITC required approximately 45s in our workstation. Conclusions: CoRaST has the potential to evaluate the correlation of MMN activity among single trials in a real-time system. Furthermore, the new method can be facilitated to study other event-related potentials (ERPs) of evoked or induced brain activity. Significance: The correlation of ERP activity among single trials can be immediately inspected during the ERP data collection in a real-time system. [Copyright &y& Elsevier]

Abstract: Objectives: This study examined the timing of the trigger pull in relation to the cardiac cycle during skilled precision shooting. Methods: Electrocardiogram was recorded from 20 junior level competitive air-rifle shooters in two separate sessions. The testing was conducted at an indoor shooting range using an optoelectronic shooting system. The experimental task was to fire a shot in the standing position at a distance of 10m from the target. Results: The results showed that the junior level shooters fired more often during the phase of 10–15% of the R wave-to-R wave (R–R) interval. With regards to the accuracy of performance, there was not any optimal location for triggering in the cardiac cycle. The length of R–R interval did not affect the relationship between shot placement within the cardiac cycle and shooting performance. Conclusion: The present results suggest that competitive shooters do not time their triggering randomly during the cardiac cycle. In contrast to the earlier empirical findings, however, the data suggest that the timing of the trigger pull in relation to the cardiac cycle is not a determinant of superior shooting performance in competitive shooters. [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]

Associative learning has been identified as one of several non-linguistic processes involved in reading acquisition. However, it has not been established whether it is an independent process that contributes to reading performance on its own or whether it is a process that is embedded in other linguistic skills (e.g., phonological awareness or phonological memory) and, therefore, contributing to reading performance indirectly. Research has shown that performance on tasks assessing associative learning, e.g., paired-associate learning (PAL) tasks, is lower in children with specific reading difficulties compared to typical readers. We explored the differential associations of two distinct verbal–visual PAL tasks (the Bala Bbala Graphogame, BBG, and a Foreign Language Learning Task, FLLT) with reading skills (word reading and pseudo-word decoding), controlling for phonological awareness, rapid naming, and letter and digit span in children at risk for reading disabilities and their typically developing peers. Our study sample consisted of 110 children living in rural Zambia, ranging in age from 7 to 18 years old (48.1% female). Multivariate analyses of covariance were used to explore the group differences in reading performance. Repeated-measures ANCOVA was used to examine children's learning across the PAL tasks. The differential relationships between both PAL tasks and reading performance were explored via structural equation modeling. The main result was that the children at risk for reading difficulties had lower performance on both PAL tasks. The BBG was a significant predictor for both word reading and pseudo-word decoding, whereas the FLLT—only for word reading. Performance on the FLLT partially mediated the association between phonological awareness and word reading. These results illustrate the partial independence of associative learning from other reading-related skills; the specifics of this relationship vary based on the type of PAL task administered. [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]

This study investigated the effects of two game features (the level of challenge and the reward system) on first and second graders' engagement during digital game-based learning of reading. We were particularly interested in determining how well these features managed to maintain children's engagement over the 8-week training period. The children (N = 138) used GraphoGame, a web-based game training letter–sound connections, at home under the supervision of parents. Data regarding the children's gaming and engagement were stored on the GraphoGame online server. A 2 × 2 factorial design was used to investigate the effects of the level of challenge (high challenge vs. high success) and the presence of the reward system (present vs. absent). Children's engagement was measured by session frequency and duration and through an in-game self-report survey that was presented at the end of the each session. According to the results, the children enjoyed GraphoGame but used it less frequently than expected. The reward system seemed to encourage the children to play longer sessions at the beginning of the training period, but this effect vanished after a few sessions. The level of challenge had no significant effect on children's engagement. The results suggest a need to investigate further the effectiveness of various game features in maintaining learner's engagement until the goals set for learning are achieved. [Copyright &y& Elsevier]

This paper addresses the question whether the cognitive underpinnings of reading and spelling are universal or language/orthography-specific. We analyzed concurrent predictions of phonological processing (awareness and memory) and rapid automatized naming (RAN) for literacy development in a large European sample of 1062 typically developing elementary school children beyond Grade 2 acquiring five different alphabetic orthographies with varying degrees of grapheme–phoneme consistency (English, French, German, Hungarian, Finnish). Findings indicate that (1) phonological processing and RAN both account for significant amounts of unique variance in literacy attainment in all five orthographies. Associations of predictors with reading speed, reading accuracy, and spelling are differential: in general, RAN is the best predictor of reading speed while phonological processing accounts for higher amounts of unique variance in reading accuracy and spelling; (2) the predictive patterns are largely comparable across orthographies, but they tend to be stronger in English than in all other orthographies. [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: 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]

Abstract: The aim of the longitudinal intervention study was to build a model of predictive values of reading fluency in three contrastive reading groups: remedial and computer-assisted remedial reading intervention, and mainstream instruction, to identify the most effective type of intervention for children with different profiles of compromised pre-reading skills. The participants were 7-year-old Finnish school beginners (N =166). Two remedial interventions took place in four weekly sessions of 45min over a period of 28weeks in Grade 1. For a child with deficits in the core pre-reading skills (letter knowledge, phonological awareness or rapid automatized naming), the computer-assisted remedial intervention would be the most successful in remediating reading fluency in the transparent Finnish language. Furthermore, children in the computer-assisted intervention were able to reach the average level of the mainstream children by the end of Grade 2. [Copyright &y& Elsevier]

Abstract: This study focuses on comparison of procedures for extracting the brain event-related potentials (ERPs) – brain responses to stimuli recorded using electroencephalography (EEG). These responses are used to study how the synchronization of brain electrical responses is associated with cognition such as how the brain detects changes in the auditory world. One such event-related response to auditory change is called mismatch negativity (MMN). It is typically observed by computing a difference wave between ERPs elicited by a frequently repeated sound and ERPs elicited by an infrequently occurring sound which differs from the repeated sounds. Fast and reliable extraction of the ERPs, such as the genuine MMN, is an important focus of studies devoted to basic cognitive brain research. In this study, we compared three procedures for extraction of the MMN elicited by infrequent duration decrements in auditory sound stimulation. These were the conventional difference wave (DW) with average standard sweep, optimal digital filtering (ODF), and recently proposed independent component analysis (ICA) decomposition procedures. The statistical comparison was made in a group of 12 healthy adults aged 23–30 years. The MMN was elicited in a passive oddball protocol presenting an auditory stimulation consisting of frequent tones of 600Hz of 100ms duration each (standard stimuli). Infrequently, one of the tones was shortened to 75, 50, or 30ms (deviant stimuli). The ICA decomposition procedure, similarly to the DW procedure with average standard sweep, extracted a cleaner MMN compared to the ODF procedure. Both procedures extracted the MMN, whose amplitude and latency characteristics concur with substantial number of publications in contrast to the ODF procedure. [Copyright &y& Elsevier]

Abstract: In this paper, a new method intended for ERP denoising in multichannel EEG data is discussed. The denoising is done by separating ERP/noise subspaces in multidimensional EEG data by a linear transformation and the following dimension reduction by ignoring noise components during inverse transformation. The separation matrix is found based on the assumption that ERP sources are deterministic for all repetitions of the same type of stimulus within the experiment, while the other noise sources do not obey the determinancy property. A detailed derivation of the technique is given together with the analysis of the results of its application to a real high-density EEG data set. The interpretation of the results and the performance of the proposed method under conditions, when the basic assumptions are violated – e.g. the problem is underdetermined – are also discussed. Moreover, we study how the factors of the number of channels and trials used by the method influence the effectiveness of ERP/noise subspaces separation. In addition, we explore also the impact of different data resampling strategies on the performance of the considered algorithm. The results can help in determining the optimal parameters of the equipment/methods used to elicit and reliably estimate ERPs. [Copyright &y& Elsevier]

Abstract: We compared the efficiency of the independent component analysis (ICA) decomposition procedure against the difference wave (DW) and optimal digital filtering (ODF) procedures in the analysis of the mismatch negativity (MMN). The comparison was made in a group of 54 children aged 8–16 years. The MMN was elicited in a passive oddball protocol presenting uninterrupted auditory stimulation consisting of two frequent alternating tones (600 and 800Hz) of 100ms duration each. Infrequently, one of the 600Hz tones was shortened to 50 or 30ms. The event related potentials (ERPs) were decomposed into the MMN-like and non-MMN-like independent components (ICs) through the FastICA algorithm. The ICA decomposition procedure extracted a cleaner MMN compared to the ODF or DW procedures. It extracted the MMN, whose characteristics concurred with the substantial number of publications demonstrating a significantly larger peak amplitude and shorter latency of the MMN in response to the more deviant stimulus (30ms) compared to the less deviant stimulus (50ms). The MMN to these two deviant stimuli did not differ in the peak amplitude or latency when it was extracted through the other two procedures. The ICA decomposition and ODF procedures, similarly, significantly improved the single trial signal-to-noise ratio (SNR) of the MMN compared to the DW procedure. Due to this improvement, the proposed ICA decomposition procedure might allow shortening of the recording session and could be used to study the MMN in paradigms similar to this with small modifications. [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]

Changes in the temporal properties of the speech signal provide important cues for phoneme identification. An impairment or inability to detect such changes may adversely affect one’s ability to understand spoken speech. The difference in meaning between the Finnish words tuli (fire) and tuuli (wind), for example, lies in the difference between the duration of the vowel /u/. Detecting changes in the temporal properties of the speech signal, therefore, is critical for distinguishing between phonemes and identifying words. In the current study, we tested whether detection of changes in speech sounds, in native Finnish speakers, would vary as a function of the position within the word that the informational changes occurred (beginning, middle, or end) by evaluating how length contrasts in segments of three-syllable Finnish pseudo-words and their acoustic correlates were discriminated. We recorded a combination of cortical components of event-related brain potentials (MMN, N2b, P3b) along with behavioral measures of the perception of the same sounds. It was found that speech sounds were not processed differently than non-speech sounds in the early stages of auditory processing indexed by MMN. Differences occurred only in later stages associated with controlled processes. The effects of position and attention on speech and non-speech stimuli are discussed. [Copyright &y& Elsevier]