Ulla Richardson

Brain sensitivity to print emerges when children learn letter-speech sound correspondences

The acquisition of reading skills is a major landmark process in a humans cognitive development. On the neural level, a new functional network develops during this time, as children typically learn to associate the well-known sounds of their spoken language with unfamiliar characters in alphabetic languages and finally access the meaning of written words, allowing for later reading. A critical component of the mature reading network located in the left occipito-temporal cortex, termed the “visual word-form system” (VWFS), exhibits print-sensitive activation in readers. When and how the sensitivity of the VWFS to print comes about remains an open question. In this study, we demonstrate the initiation of occipito-temporal cortex sensitivity to print using functional MRI (fMRI) (n = 16) and event-related potentials (ERP) (n = 32) in a controlled, longitudinal training study. Print sensitivity of fast (<250 ms) processes in posterior occipito-temporal brain regions accompanied basic associative learning of letter–speech sound correspondences in young (mean age 6.4 ± 0.08 y) nonreading kindergarten children, as shown by concordant ERP and fMRI results. The occipito-temporal print sensitivity thus is established during the earliest phase of reading acquisition in childhood, suggesting that a crucial part of the later reading network first adopts a role in mapping print and sound.

Brain Responses to Changes in Speech Sound Durations Differ Between Infants With and Without Familial Risk for Dyslexia

A specific learning disability, developmental dyslexia, is a language-based disorder that is shown to be strongly familial. Therefore, infants born to families with a history of the disorder are at an elevated risk for the disorder. However, little is known of the potential early markers of dyslexia. Here we report differences between 6-month-old infants with and without high risk of familial dyslexia in brain electrical activation generated by changes in the temporal structure of speech sounds, a critical cueing feature in speech. We measured event-related brain responses to consonant duration changes embedded in ata pseudowords applying an oddball paradigm, in which pseudoword tokens with varying /t/ duration were presented as frequent standard (80%) or as rare deviant stimuli (each 10%) with an interval of 610 msec between the stimuli. The infants at risk differ from control infants in both their initial responsiveness to sounds per se and in their change-detection responses dependent on the stimulus context. These results show that infants at risk due to a familial background of reading problems process auditory temporal cues of speech sounds differently from infants without such a risk even before they learn to speak.

Developmental pathways of children with and without familial risk for dyslexia during the first years of life.

Comparisons of the developmental pathways of the first 5 years of life for children with (N = 107) and without (N = 93) familial risk for dyslexia observed in the Jyvaskyla Longitudinal study of Dyslexia are reviewed. The earliest differences between groups were found at the ages of a few days and at 6 months in brain event-related potential responses to speech sounds and in head-turn responses (at 6 months), conditioned to reflect categorical perception of speech stimuli. The development of vocalization and motor behavior, based on parental report of the time of reaching significant milestones, or the growth of vocabulary (using the MacArthur Communicative Development Inventories) failed to reveal differences before age 2. Similarly, no group differences were found in cognitive and language development assessed by the Bayley Scales of Infant Development and the Reynell Developmental Language Scales before age 2.5. The earliest language measure that showed lower scores among the at-risk group was maximum sentence length at age 2. Early gross motor development had higher correlation to later language skills among the at-risk group rather than the control children. The most consistent predictor of differential development between groups was the onset of talking. Children who were identified as late talkers at age 2 were still delayed at the age 3.5 in most features of language-related skills-but only if they belonged to the group at familial risk for dyslexia. Several phonological and naming measures known to correlate with reading from preschool age differentiated the groups consistently from age 3.5. Our findings imply that a marked proportion of children at familial risk for dyslexia follow atypical neurodevelopmental paths. The signs listed previously comprise a pool of candidates for early predictors and precursors of dyslexia, which await validation.

Event-Related Potentials and Consonant Differentiation in Newborns with Familial Risk for Dyslexia

We measured event-related potentials (ERPs) to synthetic consonant-vowel syllables (/ba/, /da/, /ga/) from 26 newborns with familial risk for dyslexia and 23 control infants participating in the Jyväskylä Longitudinal Study of Dyslexia. The syllables were presented with equal probability and with interstimulus intervals ranging from 3,010 to 7,285 ms. Analyses of averaged ERPs from the latencies identified on the basis of principal component analysis (PCA) revealed significant group differences in stop-consonant processing in several latency ranges. At the latencies of 50-170 ms and 540-630 ms, the responses to /ga/ were larger and more positive than those to /ba/ and /da/ in the right hemisphere in the at-risk group. Between 740 and 940 ms, the responses to /ba/ and /da/ differed between anterior and posterior electrode sites in the control group. These results indicate that the cortical electric activation evoked by speech elements differs between children with and without risk for dyslexia even immediately after birth. Group-related effects at early and late latency ranges of ERPs suggest differences both in the early sound processing based on activation of afferent elements and in later phases of syllable encoding.

Speech perception of infants with high familial risk for dyslexia differ at the age of 6 months.

As yet relatively little is known of the earliest signs of dyslexia. We present evidence showing that the speech perception of 6-month-old infants from dyslexic families differs significantly from that of infants from control families with normal reading parents; the former group needed a significantly longer duration to categorize speech sounds as long. The same difference appeared in their dyslexic parents. This study shows that differences in categorizing speech sounds according to duration, which is crucial to intelligibility in Finnish, are a factor associated with familial risk for dyslexia already at infancy, which persists until adulthood in many of those suffering from dyslexia.

In search of a science-based application: A learning tool for reading acquisition

This is a story about the fate of a psychological application: from its conception to the optimistic vision surrounding its future. We hope that this application - an enjoyable learning game (www or mobile phone-based, available free of charge to the end users) for children - can at best help millions of children in their reading acquisition in the future. Its basis was created by following intensively the development of children with (N = 107) and without (N = 92) genetic (familial) risk for dyslexia from birth to puberty in the Jyväskylä Longitudinal study of Dyslexia (JLD)-project. We summarize some of the major findings of the JLD in order to facilitate understanding of the reasons and logic behind the development of the game. Originally intended as a research tool for reading acquisition, its potential for prevention of reading difficulties was quickly recognized.

Phonological similarity neighborhoods and children's short-term memory: Typical development and dyslexia

In this article, we explore whether structural characteristics of the phonological lexicon affect serial recall in typically developing and dyslexic children. Recent work has emphasized the importance of long-term phonological representations in supporting short-term memory performance. This occurs via redintegration (reconstruction) processes, which show significant neighborhood density effects in adults. We assessed whether serial recall in children was affected by neighborhood density in word and nonword tasks. Furthermore, we compared dyslexic children with typically developing children of the same age or reading level. Dyslexic children are held to have impaired phonological representations of lexical items. These impaired representations may impair or prevent the use of long-term phonological representations to redintegrate short-term memory traces. We report significant rime neighborhood density effects for serial recall of both words and nonwords, for both dyslexic and typically developing children.

Common variance in amplitude envelope perception tasks and their impact on phoneme duration perception and reading and spelling in Finnish children with reading disabilities

Our goal was to investigate auditory and speech perception abilities of children with and without reading disability (RD) and associations between auditory, speech perception, reading, and spelling skills. Participants were 9-year-old, Finnish-speaking children with RD (N = 30) and typically reading children (N = 30). Results showed significant group differences between the groups in phoneme duration discrimination but not in perception of amplitude modulation and rise time. Correlations among rise time discrimination, phoneme duration, and spelling accuracy were found for children with RD. Those children with poor rise time discrimination were also poor in phoneme duration discrimination and in spelling. Results suggest that auditory processing abilities could, at least in some children, affect speech perception skills, which in turn would lead to phonological processing deficits and dyslexia.

Infant brain responses associated with reading-related skills before school and at school age

INTRODUCTION In Jyväskylä Longitudinal Study of Dyslexia, we have investigated neurocognitive processes related to phonology and other risk factors of later reading problems. Here we review studies in which we have investigated whether dyslexic children with familial risk background would show atypical auditory/speech processing at birth, at six months and later before school and at school age as measured by brain event-related potentials (ERPs), and how infant ERPs are related to later pre-reading cognitive skills and literacy outcome. PATIENTS AND METHODS One half of the children came from families with at least one dyslexic parent (the at-risk group), while the other half belonged to the control group without any familial background of dyslexia. RESULTS Early ERPs were correlated to kindergarten age phonological processing and letter-naming skills as well as phoneme duration perception, reading and writing skills at school age. The correlations were, in general, more consistent among at-risk children. Those at-risk children who became poor readers also differed from typical readers in the infant ERP measures at the group level. ERPs measured before school and at the 3rd grade also differed between dyslexic and typical readers. Further, speech perception at behavioural level differed between dyslexic and typical readers, but not in all dyslexic readers. CONCLUSIONS These findings suggest persisting developmental differences in the organization of the neural networks sub-serving auditory and speech perception, with cascading effects on later reading related skills, in children with familial background for dyslexia. However, atypical auditory/speech processing is not likely a sufficient reason by itself for dyslexia but rather one endophenotype or risk factor.

Print-specific multimodal brain activation in kindergarten improves prediction of reading skills in second grade

Children who are poor readers usually experience troublesome school careers and consequently often suffer from secondary emotional and behavioural problems. Early identification and prediction of later reading problems thus are critical in order to start targeted interventions for those children with an elevated risk for emerging reading problems. In this study, behavioural precursors of reading were assessed in nineteen (aged 6.4 ± 0.3 years) non-reading kindergarteners before training letter-speech sound associations with a computerized game (Graphogame) for eight weeks. The training aimed to introduce the basic principles of letter-speech sound correspondences and to initialize the sensitization of specific brain areas to print. Event-related potentials (ERP) and functional magnetic resonance imaging (fMRI) data were recorded during an explicit word/symbol processing task after the training. Reading skills were assessed two years later in second grade. The focus of this study was on clarifying whether electrophysiological and fMRI data of kindergarten children significantly improve prediction of future reading skills in 2nd grade over behavioural data alone. Based on evidence from previous studies demonstrating the importance of initial print sensitivity in the left occipito-temporal visual word form system (VWFS) for learning to read, the first pronounced difference in processing words compared to symbols in the ERP, an occipito-temporal negativity (N1: 188-281 ms) along with the corresponding functional activation in the left occipito-temporal VWFS were defined as potential predictors. ERP and fMRI data in kindergarteners significantly improved the prediction of reading skills in 2nd grade over behavioural data alone. Together with the behavioural measures they explained up to 88% of the variance. An additional discriminant analysis revealed a remarkably high accuracy in classifying normal (n=11) and poor readers (n=6). Due to the key limitation of the study, i.e. the small group sizes, the results of our prediction analyses should be interpreted with caution and regarded as preliminary despite cross-validation. Nevertheless our results indicate the potential of combining neuroimaging and behavioural measures to improve prediction at an early stage, when literacy skills are acquired and interventions are most beneficial.