Biomedical subjects

Heikki Lyytinen

Publications and source records attributed to Heikki Lyytinen.

At least 19 recordsLinked to original sources

PubMed2006

Early motor development and later language and reading skills in children at risk of familial dyslexia.

Relationships between early motor development and language and reading skills were studied in 154 children, of whom 75 had familial risk of dyslexia (37 females, 38 males; at-risk group) and 79 constituted a control group (32 females, 47 males). Motor development was assessed by a structured parental questionnaire during the child's first year of life. Vocabulary and inflectional morphology skills were used as early indicators of language skills at 3 years 6 months and 5 years or 5 years 6 months of age, and reading speed was used as a later indicator of reading skills at 7 years of age. The same subgroups as in our earlier study (in which the cluster analysis was described) were used in this study. The three subgroups of the control group were 'fast motor development', 'slow fine motor development', and 'slow gross motor development', and the two subgroups of the at-risk group were 'slow motor development' and 'fast motor development'. A significant difference was found between the development of expressive language skills. Children with familial risk of dyslexia and slow motor development had a smaller vocabulary with poorer inflectional skills than the other children. They were also slower in their reading speed at the end of the first grade at the age of 7 years. Two different associations are discussed, namely the connection between early motor development and language development, and the connection between early motor development and reading speed.

Child↗

PubMed2006

Predicting delayed letter knowledge development and its relation to grade 1 reading achievement among children with and without familial risk for dyslexia.

The authors examined the developmental trajectories of children's early letter knowledge in relation to measures spanning and encompassing their prior language-related and cognitive measures and environmental factors and their subsequent Grade 1 reading achievement. Letter knowledge was assessed longitudinally at ages 4.5, 5.0, 5.5, and 6.5 years; earlier language skills and environmental factors were assessed at ages 3.5 and 4.5 years; and reading achievement was assessed at the beginning and end of Grade 1. The analyses were conducted on a longitudinal data set involving children with and without familial risk for dyslexia. Emerging from the trajectory analysis of letter knowledge were 3 separate clusters: delayed (n = 63), linearly growing (n = 73), and precocious (n = 51). The members of the delayed cluster were predominantly children with familial risk for dyslexia, and the members of the precocious cluster were predominantly control group children. Phonological sensitivity, phonological memory, and rapid naming skills predicted delayed letter knowledge. Environmental predictors included level of maternal education and the amount of letter name teaching. Familial risk for dyslexia made a significant contribution to the predictive relations. Membership in the delayed cluster predicted poor reading performance at Grade 1.

Age Factors↗

PubMed2006

The early motor milestones in infancy and later motor skills in toddlers: a structural equation model of motor development.

The relationship between the achievement of early motor milestones in infancy and later motor development was studied in 130 children with (N = 66, 35 male/31 female) and without (N = 64, 31 male/35 female) familial risk for dyslexia. A structured parental questionnaire was used to assess motor development in infancy, and the Movement Assessment Battery for Children was used to assess motor skills at age 3.5 years. No differences were found at the group level and therefore the structural equation model was constructed by entering both groups simultaneously. An Early Body Control factor, computed from the infant data, explained 38% of the variance of the Gross Motor Skills factor at the age of 3.5 years. The results suggest a relationship between gross motor milestones in infancy and gross motor skills in toddler age. Unexpectedly, the early appearance of Early Hand Control skills in infancy had a negative association with the development of the gross motor domain at 3.5 years (explanation ratio was 9%). No significant connections between early and later fine motor skills were found. The mediating role played by postural control is discussed.

Chi-Square Distribution↗

PubMed2005

Rapid serial naming: relations between different stimuli and neuropsychological factors.

We report two studies on rapid serial naming (RSN). Study 1 addressed the relations among RSN tasks comprising different stimuli. Separate components for RSN of alphanumeric and non-alphanumeric stimuli, as well as for tasks in which the stimuli alternated between categories were identified. In Study 2, phonological skills, processing speed, motor dexterity, and verbal fluency were found to explain RSN performance. The studies indicate: (1) that RSN tasks vary in their properties according to the stimuli used and according to the way the tasks are arranged, and (2) that RSN tasks are multi-componented.

Child↗

PubMed2005

Brain event-related potentials (ERPs) measured at birth predict later language development in children with and without familial risk for dyslexia.

We report associations between brain event-related potentials (ERPs) measured from newborns with and without familial risk for dyslexia and these same children's later language and verbal memory skills at 2.5, 3.5, and 5 years of age. ERPs to synthetic consonant-vowel syllables (/ba/, /da/, /ga/; presented equiprobably with 3,910-7,285 msec interstimulus intervals) were recorded from 26 newborns at risk for familial dyslexia and 23 control infants participating in the Jyväskylä Longitudinal Study of Dyslexia. The correlation and regression analyses showed that the at-risk type of response pattern at birth (a slower shift in polarity from positivity to negativity in responses to /ga/ at 540-630 msec) in the right hemisphere was related to significantly poorer receptive language skills across both groups at the age of 2.5 years. The similar ERP pattern in the left hemisphere was associated with poorer verbal memory skills at the age of 5 years. These results demonstrate that ERPs of newborns may be valid predictors of later language and neurocognitive outcomes.

Brain↗

PubMed2004

Fine mapping of the 2p11 dyslexia locus and exclusion of TACR1 as a candidate gene.

Developmental dyslexia, or reading disability, is a multigenic complex disease for which at least five loci, i.e. DYX1-3 and DYX5-6, have been clearly identified from the human genome. To date, DYX1C1 is the only dyslexia candidate gene cloned. We have previously reported linkage to 2p11 and 7q32 in 11 Finnish pedigrees. Here, we report the fine mapping of the approximately 40-cM linked region from chromosome 2 as we increased marker density to one per 1.8 cM. Linkage was supported with the highest NPL score of 3.0 (P=0.001) for marker D2S2216. Association analysis using the six pedigrees showing linkage pointed to marker D2S286/rs3220265 (P value <0.001) in the near vicinity of D2S2216. We went on to further characterise this approximately 15-cM candidate region (D2S2110-D2S2181) by adding six SNPs covering approximately 670 kb centred at D2S286/rs3220265. A haplotype pattern could no longer be observed in this region, which was therefore excluded from the candidate area. This also excluded the TACR1 (tachykinin receptor 1) gene, located at marker D2S286. The dyslexia candidate region on 2p11 is, therefore, now limited to the chromosomal area D2S2116-D2S2181, which is approximately 12 Mbp of human sequence and is at a distinct location from the previously reported DYX3 locus, raising the possibility of two distinct loci on chromosome 2p.

Blotting, Northern↗

PubMed2004

The development of children at familial risk for dyslexia: birth to early school age.

Children at risk for familial dyslexia (n = 107) and their controls (n = 93) have been followed from birth to school entry in the Jyvaskyla 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.

Case-Control Studies↗

PubMed2004

Emerging phonological awareness differentiates children with and without familial risk for dyslexia after controlling for general language skills.

Emerging phonological awareness was compared in two groups of 3.5-year-old children belonging to the Jyväskylä Longitudinal Study of Dyslexia (JLD): children with familial risk of dyslexia (at-risk group n = 98) and children without such risk (control group n = 91). Four computer animated tasks were used: Word-level and Syllable-level Segment Identification, Synthesis, and Continuation of Phonological Units. The control group children manifested higher mastery than children in the at-risk group in phonological awareness, and the proportion of children with a low phonological awareness mean score was 2.5 times higher in the at-risk group than in the control group. In both groups, phonological awareness at 3.5 years was predicted by early language skills assessed between 14 and 26 months of age, and it was also associated with concurrent language. The difference between the at-risk and control group at 3.5-year in phonological awareness remained significant, even when the effect of other language skills such as productive and receptive vocabulary, and mastery of inflections, measured both at earlier ages and concurrently were controlled for. Our findings indicate that familial risk for dyslexia is reliably reflected in emerging phonological awareness already at this early age and it can be assessed independently of other language skills.

Articulation Disorders↗

PubMed2004

Maturational effects on newborn ERPs measured in the mismatch negativity paradigm.

The mismatch negativity (MMN) component of event-related potentials (ERPs), a measure of passive change detection, is suggested to develop early in comparison to other ERP components, and an MMN-like response has been measured even from preterm infants. The MMN response in adults is negative in polarity at about 150-200 ms. However, the response measured in a typical MMN paradigm can also be markedly different in newborns, even opposite in polarity. This has been suggested to be related to maturational factors. To verify that suggestion, we measured ERPs of 21 newborns during quiet sleep to rarely occurring deviant tones of 1100 Hz (probability 12%) embedded among repeated standard tones of 1000 Hz in an oddball sequence. Gestational age (GA) and two cardiac measures, vagal tone (V) and heart period (HP), were used as measures of maturation. GA and HP explained between 36% and 42% of the total variance of the individual ERP peak amplitude (the largest deflection of the difference wave at a time window of 150-375 ms) at different scalp locations. In the discriminant function analyses, GA and HP as classifying variables differentiated infants in whom the peak of the difference wave had positive polarity from those with a negative polarity at an accuracy level ranging from 72% to 91%. These results demonstrate that during quiet sleep, maturational factors explain a significant portion of the ERP difference wave amplitude in terms of its polarity, indicating that the more mature the ERPs are, the more positive the amplitude. The present study suggests that maturational effects should be taken into account in ERP measurements using MMN paradigms with young infants.

Acoustic Stimulation↗

PubMed2004

Automatic and controlled processing of acoustic and phonetic contrasts.

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.

Acoustic Stimulation↗

PubMed2004

Co-occurrence of developmental delays in a screening study of 4-year-old Finnish children.

The aim of this population study was to examine the severity and prevalence of co-occurring developmental delays in 4-year-old children, the rate of overlapping problems, and sex differences. A sample of 434 children (196 males, 238 females; mean age 4 years 3 months, SD 1 month) were administered the 'Lene' test: a comprehensive neurodevelopmental screening test. Results suggest that co-occurrence of attention-behavioural, motor-perceptual, and language delays occurring in school-aged children could already be detected at the age of 4 years. Isolated delays were usually mild, but co-occurring difficulties were mostly moderate or severe. Overlap between developmental delays depended on the severity of the problems. It emerged that males had more severe and more often co-occurring problems than females. Co-occurrence of developmental delays as a risk factor at the early stage of development is discussed.

Catchment Area, Health↗

PubMed2003

A candidate gene for developmental dyslexia encodes a nuclear tetratricopeptide repeat domain protein dynamically regulated in brain.

Approximately 3-10% of people have specific difficulties in reading, despite adequate intelligence, education, and social environment. We report here the characterization of a gene, DYX1C1 near the DYX1 locus in chromosome 15q21, that is disrupted by a translocation t(2;15)(q11;q21) segregating coincidentally with dyslexia. Two sequence changes in DYX1C1, one involving the translation initiation sequence and an Elk-1 transcription factor binding site (-3G --> A) and a codon (1249G --> T), introducing a premature stop codon and truncating the predicted protein by 4 aa, associate alone and in combination with dyslexia. DYX1C1 encodes a 420-aa protein with three tetratricopeptide repeat (TPR) domains, thought to be protein interaction modules, but otherwise with no homology to known proteins. The mouse Dyx1c1 protein is 78% identical to the human protein, and the nonhuman primates differ at 0.5-1.4% of residues. DYX1C1 is expressed in several tissues, including the brain, and the protein resides in the nucleus. In human brain, DYX1C1 protein localizes to a fraction of cortical neurons and white matter glial cells. We conclude that DYX1C1 should be regarded as a candidate gene for developmental dyslexia. Detailed study of its function may open a path to understanding a complex process of development and maturation of the human brain.

Base Sequence↗

PubMed2003

Timing of triggering in relation to the cardiac cycle in nonelite rifle shooters.

This study investigated the timing of the trigger pull in relation to the cardiac cycle during air rifle shooting. Electrocardiogram) was recorded from 20 male nonelite rifle shooters in two separate testing sessions. The testing was conducted at an indoor shooting range using an optoelectronic shooting system. Each participant fired a shot in the standing position at a distance of 10 m from the target. The results showed that compared to random triggering, the shooters fired more often during the phase of 10-50% of the R wave-to-R wave (R-R) interval and less often during the phase of 50-90%. With regard to performance accuracy, the participants exhibited average or above average performance, when the shot occurred in the beginning (0-50%) and in the end (70-99%) of the R-R interval. The less optimal range for the triggering was located within the 50-70% phase of the R-R interval. The length of R-R interval (i.e., heart rate) did not affect the relation of shot placement within the cardiac cycle to the accuracy of shooting performance. The present results extend previous findings by showing that in air rile shooting the optimum firing time within the cardiac cycle may be located in the systolic phase. It is argued that the systole-diastole dichotomy is not a sufficiently accurate way to investigate the effects of shot placement in the cardiac cycle. Further research is needed to examine the extent to which the relationship between the timing of triggering within the cardiac cycle and shooting performance depends a shooter's skill level.

Adult↗

PubMed2003

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.

Acoustic Stimulation↗

PubMed2002

Abnormal auditory cortical activation in dyslexia 100 msec after speech onset.

Reading difficulties are associated with problems in processing and manipulating speech sounds. Dyslexic individuals seem to have, for instance, difficulties in perceiving the length and identity of consonants. Using magnetoencephalography (MEG), we characterized the spatio-temporal pattern of auditory cortical activation in dyslexia evoked by three types of natural bisyllabic pseudowords (/ata/, /atta/, and /a a/), complex nonspeech sound pairs (corresponding to /atta/ and /a a/) and simple 1-kHz tones. The most robust difference between dyslexic and non-reading-impaired adults was seen in the left supratemporal auditory cortex 100 msec after the onset of the vowel /a/. This N100m response was abnormally strong in dyslexic individuals. For the complex nonspeech sounds and tone, the N100m response amplitudes were similar in dyslexic and nonimpaired individuals. The responses evoked by syllable /ta/ of the pseudoword /atta/ also showed modest latency differences between the two subject groups. The responses evoked by the corresponding nonspeech sounds did not differ between the two subject groups. Further, when the initial formant transition, that is, the consonant, was removed from the syllable /ta/, the N100m latency was normal in dyslexic individuals. Thus, it appears that dyslexia is reflected as abnormal activation of the auditory cortex already 100 msec after speech onset, manifested as abnormal response strengths for natural speech and as delays for speech sounds containing rapid frequency transition. These differences between the dyslexic and nonimpaired individuals also imply that the N100m response codes stimulus-specific features likely to be critical for speech perception. Which features of speech (or nonspeech stimuli) are critical in eliciting the abnormally strong N100m response in dyslexic individuals should be resolved in future studies.

Acoustic Stimulation↗

PubMed2002

Cortical activation during spoken-word segmentation in nonreading-impaired and dyslexic adults.

We used magnetoencephalography to elucidate the cortical activation associated with the segmentation of spoken words in nonreading-impaired and dyslexic adults. The subjects listened to binaurally presented sentences where the sentence-ending words were either semantically appropriate or inappropriate to the preceding sentence context. Half of the inappropriate final words shared two or three initial phonemes with the highly expected semantically appropriate words. Two temporally and functionally distinct response patterns were detected in the superior temporal lobe. The first response peaked at approximately 100 msec in the supratemporal plane and showed no sensitivity to the semantic appropriateness of the final word. This presemantic N100m response was abnormally strong in the left hemisphere of dyslexic individuals. After the N100m response, the semantically inappropriate sentence-ending words evoked stronger activation than the expected endings in the superior temporal cortex in the vicinity of the auditory cortex. This N400m response was delayed for words starting with the same two or three first few phonemes as the expected words but only until the first evidence of acoustic-phonetic dissimilarity emerged. This subtle delay supports the notion of initial lexical access being based on phonemes or acoustic features. In dyslexic participants, this qualitative aspect of word processing appeared to be normal. However, for all words alike, the ascending slope of the semantic activation in the left hemisphere was delayed by approximately 50 msec as compared with control subjects. The delay in the auditory N400m response in dyslexic subjects is likely to result from presemantic-phonological deficits possibly reflected in the abnormal N100m response.

Acoustic Stimulation↗

PubMed2002

Development of early motor skills and language in children at risk for familial dyslexia.

Differences in motor development and the relationship between motor and language development were studied in 88 children with familial risk for dyslexia (43 females, 45 males; at-risk group) and 88 children without familial risk for dyslexia (35 females, 53 females; control group; n=176) during the first two years of life. A structured parental questionnaire was used to assess motor development. Expressive language skills were assessed at the age of 18 months with the Reynell Developmental Language Scales and at 18 and 24 months with the MacArthur Communicative Development Inventories. At group level, the motor development of children in both the at-risk and control groups was similar. However, motor development showed a different pattern in these groups. Cluster analyses revealed three clusters in the control group: 'fast motor development', 'slow fine motor development', and 'slow gross motor development'. In the at-risk group, only two clusters were found: 'slow motor development' and 'fast motor development'. A significant difference (p=0.03) was found between the clusters in the MacArthur Communicative Development Inventories. Children with familial risk for dyslexia and slow motor development had a smaller vocabulary and produced shorter sentences than the all other children. Associations between motor and language difficulties are discussed.

Child↗

PubMed2002

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.

Acoustic Stimulation↗