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Biomedical subjects

H Lyytinen

Publications and source records attributed to H Lyytinen.

46 records · Page 3Linked to original sources
PubMed1991

Corpus callosum morphology in attention deficit-hyperactivity disorder: morphometric analysis of MRI.

Although behavioral evidence provides support for the notion that attention deficit-hyperactivity disorder (ADHD) is related to central nervous system dysfunction, there is little direct evidence to reveal which neurometabolic systems or brain structures are involved. Recent magnetic resonance imaging (MRI) studies suggest that, compared to nondisabled controls, ADHD children may have a smaller right frontal region. Morphometric analysis of MRI scans was used in this exploratory study to determine whether correlated regional variation might exist in the corpus callosum of children with ADHD. While all MRI scans were judged to be clinically normal, morphometric analysis revealed that, compared to nondisabled controls, ADHD children had a smaller corpus callosum, particularly in the region of the genu and splenium, and in the area just anterior to the splenium. Interhemispheric fibers in these regions interconnect the left and right frontal, occipital, parietal, and posterior temporal regions. These results suggest that subtle differences may exist in the brains of children with ADHD and that deviations in normal corticogenesis may underlie the behavioral manifestations of this disorder.

Attention Deficit Disorder with Hyperactivity↗
PubMedDate not supplied

E-wave and heart rate responses during anticipation of nonmotor events.

This study concentrated on three main questions: 1) can anticipatory late negative shift (expectancy wave, E-wave) be elicited in nonmotor S1-S2 paradigm, 2) is it sensitive to variation of emotional aspects of the task and 3) is there a connection between heart rate (HR) responses and E-wave. S1 was a letter row that was replaced tachistoscopically by another letter row (S2). The task of the subjects (n = 12) was to detect if the critical aspects of S2 were similar to S1. After their delayed response they received feedback of their performance. The emotional aspects of the task were varied by presenting aversive noise bursts at the end of the feedback period either always, contingently to their performance or not at all. A negative shift was present both before S2 and aversive noise (when presented). Varying the emotional aspects of the task had an effect on the amplitude of the E-wave. There was also a connection between E-wave and heart rate responses: heart rate response seemed to be a precondition for E-wave elicitation. The results support Simons's conclusion that nonmotor E-wave reflects specifically emotional anticipation.

Acoustic Stimulation↗
PubMedDate not supplied

Auditory event-related potentials in the study of developmental language-related disorders.

This article reviews recent auditory event-related potential (ERP) studies of developmental language disorder (DLD) and dyslexia/reading disorder (RD). The possibility of using ERPs in searching for precursors of these disorders in the early development of infants at risk is also discussed. Differences in exogenous/sensory ERPs at the latency range of P1 and N1-P2 components have been reported between groups with DLD and RD and control groups. Latency differences between the groups may be related to a common timing deficit suggested by some researchers to be one of the possible underlying factors both in DLD and dyslexia. N1 amplitude group differences may be partly related to arousal/attentional factors and partly to the 'tuning' of the auditory sensory system. Mismatch negativity deviations in DLD children seem to indicate differences in sensory memory functions. Differences between the reviewed clinical groups and controls exist also in the endogenous P3 component, though less consistently in DLD children. In both clinical groups the P3 amplitudes are, in general, lower and the latencies longer compared to those in controls. These findings are discussed in terms of possible differences in higher cognitive functions that are not specific to modality. Altered hemispheric asymmetries in DLD and RD children, as compared to controls, are commonly found in many of the reviewed ERP components. Differences in ERPs of DLD and dyslexic children in comparison to controls may not reflect only maturational lag but also more fundamental processing deficiencies.

Adolescent↗
PubMedDate not supplied

Predicting delay in reading achievement in a highly transparent language.

A random sample of 91 preschool children was assessed prior to receiving formal reading instruction. Verbal and nonverbal measures were used as predictors for the time of instruction required to accurately decode pseudowords in the highly orthographically regular Finnish language. After 2 years, participants were divided into four groups depending on the duration of instruction they had required to reach 90 % accuracy in their reading of pseudowords. Participants were classified as precocious decoders (PD), who could read at school entry; early decoders (ED), who learned to read within the first 4 months of Grade 1; ordinary decoders (OD), who learned to read within 9 months; and late decoders (LD), who failed to reach the criterion after 18 months of reading instruction at Grade 2. Phonological awareness played a significant role only in differentiating PD from ED and OD. However, phonological awareness failed to predict the delayed learning process of LD. LD differed from all other groups in visual analogical reasoning in an analysis not containing phonological awareness measures. Letter knowledge and visual analogical reasoning explained above 90% of the PD-LD difference. Preschool composite (objects, colors, and digits) naming speed measures best predicted reading fluency at the end of Grade 2. The supportive role of orthographic knowledge in phonological awareness, the role of visual analogical reasoning, and the inability of phonological measures to discriminate late decoders are discussed.

Child↗
PubMedDate not supplied

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.

Auditory Perceptual Disorders↗
PubMedDate not supplied

Comparing efficacies of neurocognitive treatment and homework assistance programs for children with learning difficulties.

The purpose of the study was to analyze the relative efficacies of two treatments for children with learning difficulties. The first treatment consisted of multiple training components targeting specific cognitive and behavioral factors; the second treatment provided emotional support and supervision of school tasks. The participants were 94 Chilean schoolchildren (6 to 11 years of age). The efficacies were compared on (a) neurocognitive tests, (b) school achievement tests, and (c) behavior in school and at home. The results indicated that both groups improved on most of the outcome measures. The first group showed best results in parents' rating of home behavior, and the second group in reading. The findings also emphasized the importance of emotional support and the inclusion of a parents' group in treatment for children with learning difficulties.

Achievement↗
PubMedDate not supplied

Two-year group treatment for children with learning difficulties: assessing effects of treatment duration and pretreatment characteristics.

The results of a 2-year treatment study of children with learning problems are reported. During the first treatment year, half of the children participated in a multifaceted neurocognitive treatment and the other half in a treatment that provided supervision of school tasks and peer group support. During the second treatment year, all children participated in the neurocognitive treatment. The participants were 74 Chilean children 6 to 11 years old. The issues under investigation were the effect of treatment duration, and the relationship between pretreatment neurocognitive and behavioral characteristics and academic treatment outcome. The results indicated that significant gains occurred during both the first and the second treatment year. No major differences were found between the treatment groups. Pretreatment negative behavioral traits were associated with lesser academic growth in the group participating in the homework supervision treatment but not in the neurocognitive treatment group.

Analysis of Variance↗
PubMedDate not supplied

The development of phonological abilities and their relation to reading acquisition: case studies of six Finnish children.

The relation between phonological abilities and reading acquisition and the interindividual variation in the development of different phonological manipulation skills were assessed for six 7-year-old Finnish nonreaders. Intensive time series data were collected by following the children for 13 months. Assessments were conducted every 4 weeks with five phonological manipulation tests. The results indicated gradual progress at the group level. However, analysis of the individual profiles indicated large interindividual variation in the rate of improvement and in the relation between different manipulation skills and reading acquisition.

Awareness↗
PubMedDate not supplied

Lateralization of speech processing in the brain as indicated by mismatch negativity and dichotic listening.

The goal of the present study was to evaluate the differences between dichotic listening and mismatch negativity as measures of speech lateralization in the human brain. For this purpose, we recorded the magnetic equivalent of the mismatch negativity, elicited by consonant-vowel syllable change, and tested the same subjects in the dichotic listening procedure. The results showed that both methods indicated left-hemisphere dominance in speech processing. However, the mismatch negativity, as compared to the right-ear advantage, suggested slightly stronger left-hemisphere dominance in speech processing. No clear correlation was found between the laterality indexes of mismatch negativity and right-ear advantage calculated from dichotic listening results. The possible explanation for this finding would be that these two measures reflect different stages of speech processing in the human brain.

Adult↗