Biomedical subjects

G Schulte-Körne

Publications and source records attributed to G Schulte-Körne.

At least 19 recordsLinked to original sources

PubMed2006

Interrelationship and familiality of dyslexia related quantitative measures.

Dyslexia is a complex gene-environment disorder with poorly understood etiology that affects about 5% of school-age children. Dyslexia occurs in all languages and is associated with a high level of social and psychological morbidity for the individual and their family; approximately 40-50% have persistent disability into adulthood. The core symptoms are word reading and spelling deficits, but several other cognitive components influence the core phenotype. A broad spectrum of dyslexia related phenotypes, including phonological decoding, phoneme awareness, orthographic processing, short-term memory, rapid naming and basic mathematical abilities, were investigated in large sample of 287 German dyslexia families. We explored the interrelationship between the component phenotypes using correlation and principal component analyses (PCA). In addition, we estimated familiality for phenotypes as well as for the factors suggested by PCA. The correlation between the component phenotypes varied between -0.1 and 0.7. The PCA resulted in three factors: a general dyslexia factor, a speed of processing factor and a mathematical abilities factor. The familiality estimates of single components and factors ranged between 0.25 and 0.63. Instead of analyzing single dyslexia-related components, multivariate analyses including factor analytic approaches may help in the identification of susceptibility genes.

Adolescent↗

PubMed2005

Linkage analyses of chromosomal region 18p11-q12 in dyslexia.

Dyslexia is characterized as a significant impairment in reading and spelling ability that cannot be explained by low intelligence, low school attendance or deficits in sensory acuity. It is known to be a hereditary disorder that affects about 5% of school aged children, making it the most common of childhood learning disorders. Several susceptibility loci have been reported on chromosomes 1, 2, 3, 6, 15, and 18. The locus on chromosome 18 has been described as having the strongest influence on single word reading, phoneme awareness, and orthographic coding in the largest genome wide linkage study published to date (Fisher et al., 2002). Here we present data from 82 German families in order to investigate linkage of various dyslexia-related traits to the previously described region on chromosome 18p11-q12. Using two- and multipoint analyses, we did not find support for linkage of spelling, single word reading, phoneme awareness, orthographic coding and rapid naming to any of the 14 genotyped STR markers. Possible explanations for our non-replication include differences in study design, limited power of our study and overestimation of the effect of the chromosome 18 locus in the original study.

Adolescent↗

PubMed2004

Spatial-frequency- and contrast-dependent visible persistence and reading disorder: no evidence for a basic perceptual deficit.

The aetiology of dyslexia is still unclear, the most widely and controversially discussed theory is the magnocellular deficit hypothesis. One of the first and most influential paradigms used to investigate this visual deficit in dyslexia is the visible persistence (VP). However results on VP are decisively influenced by the method measuring VP. Lovegrove et al. (1986) repeatedly found a longer VP in reading disabled children which is significantly influenced by spatial frequency and contrast. However, these results were not investigated with the same method to date. Seventy-six unselected 2nd grade students (41 boys, 35 girls) of a rural primary school were investigated with an identical experimental design comparable to the Lovegrove et al. (1986) studies. Comparing reading disabled (n = 17) with controls (n = 34) no evidence for a longer VP in the reading disabled group was found. Additionally, correlation analysis revealed no evidence for a significance of VP for spelling, phoneme awareness and speech discrimination. This study does not encourage either a magnocellular nor parvocellular deficit in dyslexia.

Analysis of Variance↗

PubMed2004

Neurophysiological correlates of word recognition in dyslexia.

The neurobiological basis of learning word spellings and recognition of recently learned words was assessed in a learning experiment in 9 dyslexics and 9 controls male adolescents. In a recognition paradigm previously learned pseudowords and graphic symbols were presented 50 times each interspersed pseudo-randomly between 3 unlearned items which were repeated 50 times and 150 filler pseudowords. The electrophysiological correlate of recognition of learned pseudowords and graphic symbols was a positivity around 600 ms. For pseudowords the amplitude of this ERP component was significantly attenuated in the dyslexic group, no differences between the groups were found for recognition of graphic material. These data suggest that dyslexic children are able to learn the spelling of simple words, however, the neurophysiological correlate of recognition of these learned words is significantly attenuated. This result strengthens the view that dyslexic children are not generally impaired in recognition memory but specific for linguistic material like words.

Adolescent↗

PubMed2003

[Practice in spelling in remedial groups--results of an evaluation study in secondary education].

OBJECTIVE: This study aims to evaluate in a school-based tutoring setting a training program for spelling (Marburger Rechtschreibtraining) that has proven effective in non-school settings. A spelling training program already in use at the school serves as the control condition. METHODS: A total of 37 second- and third-graders rated by their teachers as spelling disabled participated in the study. In addition to their regular lessons, the children received two added lessons in small tutoring groups each week. RESULTS: The skills of the children in the tutoring program had increased significantly two years later regardless of the method used. This effect was confirmed both by tests as well as by teachers' and parental reports. However, the children's emotional attitudes towards school failed to change significantly. The control group that had received no tutoring improved as well. CONCLUSIONS: Tutoring spelling disabled children in small groups is an effective method for improving their reading and spelling abilities. Nevertheless, the fact that the skills of children in the control group without any tutoring also improved raises a number of questions. The choice of method in our study had no effect on the outcome. Our study was unable to systematically evaluate a number of potential influences (such as sample selection); these should be investigated further.

Child↗

PubMed2003

[Follow-up of a sample of children with reading-spelling disorders in adulthood].

OBJECTIVE: Only a few studies--especially in Germany--deal with the long-term outcome for dyslexic children. The aim of our study was to assess a group of former students of a boarding school for dyslexic children (Chrisophorus School Oberurff). METHODS: 29 adults with spelling disorder were examined 20 years after they had left school. Their spelling ability was measured with the Mannheimer Spelling Test (MRT), psychiatric symptoms with the Symptom Checklist by Derogatis (SCL-90), occupational status with the Wegener "Magnitude-Prestigeskala" (Magnitude of Prestige Scale), and intelligence with the Culture Fair Intelligence Test (CFT 20). A self-constructed questionnaire was used to assess subjects' self-perception of their reading and spelling abilities, the role of reading and spelling in their work, and the influence of reading and spelling on their choice of employment. RESULTS: Spelling skills at follow-up were more than 0.5 standard deviations above the spelling skills measured at school. The occupational status is rather high at 75% above average. There is no evidence of a significant load of psychiatric symptoms among the dyslexic adults. CONCLUSIONS: The general finding is a favorable development of children with spelling disorder 20 years after attendance at a special boarding school for dyslexic children. High IQ, the high socioeconomic status of the probands and their parents, and the long-lasting remedial work at school are most likely the relevant factors for this development.

Adolescent↗

PubMed2001

Speech perception deficit in dyslexic adults as measured by mismatch negativity (MMN).

Deficits in phonological processing are known to play a major role in the aetiology of dyslexia, and speech perception is a prerequisite condition for phonological processing. Significant group differences between dyslexics and controls have been found in the categorical perception of synthetic speech stimuli. In a previous work, we have demonstrated that these group differences are already present at an early pre-attentive stage of signal processing in dyslexic children: the late component of the MMN elicited by passive speech perception was attenuated in comparison to a control group. In this study, 12 dyslexic adults and 13 controls were assessed using a passive oddball paradigm. Mismatch negativity (MMN) was determined for both tone and speech stimuli. The tone stimuli yielded two MMN components, but no group differences. Three components were found for the speech stimuli. Multivariate testing for group differences yielded a significant result, and univariate P values revealed significant differences between dyslexics and controls in two of the three time windows. This suggests that speech perception as measured on an early, pre-attentive level plays a major role in dyslexia not only in children (as shown in our previous study) but also in adults.

Acoustic Stimulation↗

PubMed2001

[Marburg Spelling Training program--results of a brief intervention].

OBJECTIVES: The Marburg Spelling Training Program was administered to a sample of 10 spelling-disabled primary school pupils (2nd-4th graders) over three months in an individual setting. RESULTS: Statistical analyses yielded significant improvements in spelling and reading test performances, but none yet in the emotional stress caused by the problems. CONCLUSION: The Marburg Spelling Training Program has now proven to be effective not only in long-term, but also in short-term intervention.

Case-Control Studies↗

PubMed2001

[Diagnosis of reading and spelling disorder].

The ICD-10 calls for the use of tables that account for the correlation between intelligence and spelling or reading, respectively (regression model) in the diagnosis of dyslexia. In this paper we discuss the consequences that arise from this recommendation with respect to the interpretation of psychometric tests. In addition, a table is presented that contains the data required to make diagnostic decisions based on the regression model. Furthermore, an expected prevalence rate was calculated using randomized computer data.

Adolescent↗

PubMed2001

Annotation: Genetics of reading and spelling disorder.

Recent advances in understanding the genetics of reading and spelling disorder are reviewed and, based on theoretical models of reading development, different related phenotypes such as phonological and orthographic processing are examined. Family and twin studies show a moderate to high familiality and heritability. Segregation analyses suggest a major gene effect, with reduced penetrance in females, as well as a polygenic model. Linkage analyses and an association study have identified possible loci on chromosomes 6 and 15. These results suggest that reading and spelling disorder should be regarded as a complex disorder, strongly influenced by genetic factors. However, the role of environmental factors should also be considered as the clinical implications of the genetic findings in terms of aetiology and intervention still require far more exploration.

Diseases in Twins↗

PubMed2000

[Gottinger Form Reproduction Test (GFT)--results from an unselected sample].

The Göttingen Form Reproduction Test (GFT) is a relatively old method of assessing visuo-motor coordination that is still often performed in clinical practice. Based on a sample of 72 unselected second-graders, it was shown that the mean percent ranks are too high. GFT percent ranks then should be interpreted with extreme caution in the course of clinical diagnosis.

Brain Injuries↗

PubMed2000

[Contingent negative variation (CNV) in children with hyperkinetic syndrome--an experimental study using the Continuous Performance Test (CPT)].

OBJECTIVES: Evaluation of event-related potentials for selective attention in attention deficit/hyperactivity disordered children. METHODS: Selective attention processes were examined in a group of 18 boys aged 6 to 12 years with attention deficit/hyperactivity disorder and compared with the data of a control group of 21 age and sex matched boys. Parallel thereto the event-related potentials (ERP) were derived during the test at the electrode positions Fz, Cz, Pz, and Oz with reference to the linked ears. RESULTS: Two components of the contingent negative variation (CNV) with different topography were identified in the ERP following a preparatory stimulus (CNV-1: 600 to 1100 ms and CNV-2: 1000 to 1500 ms after the stimulus). There were no group differences at the behavioural level (number of correct detected targets, number of errors). Significant group differences resulted with regard to the topography of the two CNV components. Children with ADD showed an attenuated frontal CNV-1 amplitude and a trend towards increased CNV-1 and CNV-2 occipital amplitudes. CONCLUSIONS: The results support the hypothesis of impaired frontal inhibitory processes in children with ADD.

Attention↗

PubMed1999

Pre-attentive processing of auditory patterns in dyslexic human subjects.

It has been hypothesized that auditory temporal processing plays a major role in the aetiology of dyslexia. Event-related brain potentials (mismatch negativity, MMN) of auditory temporal processing were assessed in 15 dyslectic adults and 20 controls. A complex tonal pattern was used where the difference between standard and deviant stimuli was the temporal, not the frequency structure. Dyslexics had a significantly smaller MMN in the time window of 225-600 ms. This result shows that dyslexics have a significant pre-attentive deficit in processing of rapid temporal patterns suggesting that it may be the temporal information embedded in speech sounds, rather than phonetic information per se, that resulted in the attenuated MMN found in dyslexics in previous studies. MMN scalp topographies were similar for both groups, showing a maximum over fronto-central leads.

Acoustic Stimulation↗

PubMed1999

Attenuated hemispheric lateralization in dyslexia: evidence of a visual processing deficit.

There is controversial evidence that deficits in the processing of low contrast and low spatial frequency stimuli are of importance in the pathogenesis of dyslexia. Fifteen adult dyslexics and 19 controls were examined using visual evoked potentials (VEP) at varying spatial frequencies (2 and 11.33 cpd) and contrasts (0.2, 0.4, 0.6, 0.8). Our results show that the amplitude of VEPs following different spatial frequencies and contrasts did not differentiate between dyslexics and controls. Further, we found significantly higher amplitudes of the P1 and P2 over the right occipital cortex. For the P2, this hemispheric asymmetry was not found in the dyslexic group suggesting a specific low level visual processing deficit in the right occipital region in dyslexia.

Adult↗

PubMed1999

The role of phonological awareness, speech perception, and auditory temporal processing for dyslexia.

There is strong evidence that auditory processing plays a major role in the etiology of dyslexia. Auditory temporal processing of non-speech stimuli, speech perception, and phonological awareness have been shown to be influential in reading and spelling development. However, the relationship between these variables remains unclear. In order to analyze the influence of these three auditory processing levels on spelling, 19 dyslexic and 15 control children were examined. Significant group differences were found for all speech variables, but not for any non-speech variable. Structural equation modeling resulted in a fairly simple model with direct paths to the respective next lower level. One additional path from preattentive speech processing to spelling had to be included in order to improve the model fit. These results strengthen the role of speech and phonological processing for the etiology in dyslexia.

Attention↗

PubMed1999

Genetic linkage analysis with dyslexia: evidence for linkage of spelling disability to chromosome 15.

Dyslexia (reading and spelling disability) is one of the most frequently diagnosed disorders in childhood. Twin studies of dyslexia have indicated that deficits in spelling are substantially heritable and that the heritability of spelling deficits is higher than the heritability of reading deficits. We conducted a linkage study for spelling disability in seven multiplex families from Germany. Following previously reported linkage findings of components of dyslexia to chromosome 6p21-p22 and 15q21, we genotyped 26 microsatellite markers covering all of chromosome 6, and 13 microsatellite markers covering all of chromosome 15. While the chromosome 6 data were negative, results from chromosome 15 markers supported a locus on 15q21. The highest two-point LOD score was 1.26 with marker D15S143 at theta = 0. A multipoint LOD score of 1.78 (p = 0.0042) was achieved with a maximum at D15S132. Thus, our results provide independent support for a dyslexia gene on the long arm of chromosome 15.

Child↗

PubMed1999

The influence of different diagnostic approaches on familial aggregation of spelling disability.

The influence of different diagnostic approaches on familial aggregation of spelling disability was investigated in three studies. In the first study, in a sample of 32 dyslexic children and their families, we found significantly increased rates of spelling-disabled sibs and parents by applying the IQ-discrepancy criterion. There was no evidence for the assumption that IQ-discrepancy and low achievement criteria define different subgroups of spelling disorder regarding familial aggregation. In the second study, in a sample of 79 adults, it could be demonstrated that questionnaire data can be used as an appropriate method to classify adult probands as spelling disabled with a correct classification rate above 87%. In the third study, a subgroup of dyslexic boys could be characterized by a lack of the N1-component in visual evoked potentials which was most prominent in those boys whose spelling scores were more than 1.5 standard deviations below their intelligence level. This subgroup could be interesting also for genetic research.

Achievement↗

PubMed1998

Auditory processing and dyslexia: evidence for a specific speech processing deficit.

In order to investigate the relationship between dyslexia and central auditory processing, 19 children with spelling disability and 15 controls at grades 5 and 6 were examined using a passive oddball paradigm. Mismatch negativity (MMN) was determined for tone and speech stimuli. While there were no group differences for the tone stimuli, we found a significantly attenuated MMN in the dyslexic group for the speech stimuli. This finding leads to the conclusion that dyslexics have a specific speech processing deficit at the sensory level which could be used to identify children at risk at an early age.

Acoustic Stimulation↗