The temporal dynamics of coherent motion processing in autism spectrum disorder: evidence for a deficit in the dorsal pathway

Individuals with autism spectrum disorder (ASD) show impairments in processing coherent motion which have been proposed to be linked to a general deficit in the dorsal visual pathway. However, few studies have investigated the neural mechanisms underlying coherent motion processing in ASD. Thus, the aim of this study was to further test the hypothesis of a dorsal pathway deficit in ASD using visual evoked potentials (VEPs). 16 children and adolescents with ASD and 12 typically developing controls were examined with VEPs elicited by a random dot kinematogram. After an initial experimental sequence, where subjects were presented randomly moving dots, a fraction of the dots moved coherently (dependent on the level of coherence, 20%, 40%, or 60% of the dots) to the left or right side. Subjects were asked to detect the direction of coherent motion via button press. On the behavioural level, no significant group differences emerged. On the neural level, coherently moving dots elicited a N200 followed by a late positive potential (P400). ASD subjects exhibited a reduced N200 amplitude compared to controls. Moreover, in the ASD group, a trend for a negative relationship between N200 amplitude and a measure of autistic pathology was revealed. The present study provides strong support of a dorsal stream deficiency in the disorder and renders alternative explanations for impaired coherent motion processing in ASD less likely. Together with findings from related research fields, our data indicate that deviances in the N200 during coherent motion perception might be fundamental to ASD.

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.

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.

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.

Visual information processing in dyslexic children

OBJECTIVE

Several studies presented evidence for magnocellular deficits in dyslexics both in behavioural as well as in electrophysiological data of local electrode sites. We investigated two well-known paradigms (motion-onset and random-dot-kinematogram) with regard to global electrophysiological parameters.

METHODS

Twenty-one-channel event-related potentials (ERPs) of 16 dyslectic and 15 control children were analyzed with reference-independent methods. For each paradigm quasi stable microstates were identified by means of a data-driven segmentation procedure and compared between both groups.

RESULTS

Differences in global ERP responses between dyslexic and control children could be found for rapid moving gratings but not for the dot coherence.

CONCLUSIONS

Dyslexic children seem to have some highly specific visual deficits in processing moving stimuli. These deficits can be related to the magnocellular system.

Nachuntersuchung einer Stichprobe von lese-rechtschreibgestörten Kindern im Erwachsenenalter

Zusammenfassung: Fragestellung: Der Langzeitverlauf der Lese-Rechtschreibstörung bis ins Erwachsenenalter ist bisher kaum untersucht, insbesondere liegen kaum Studien mit deutschsprachigen Kindern vor. Anhand einer Katamnesestudie von ehemaligen Schülern der Christophorus Schule Oberurff wird die Entwicklung der Rechtschreibleistung, der Intelligenz, der psychischen und sozialen Entwicklung von lese- und rechtschreibschwachen Schülern untersucht. Methode: 29 ehemalige Schüler wurden im Durchschnitt nach 20 Jahren nachuntersucht. Die Rechtschreibleistung wurde mit dem Mannheimer Rechtschreibtest (MRT), die Psychische Befindlichkeit mit der Symptom-Checkliste von Derogatis (SCL-90), der Berufserfolg mit der «Magnitude-Prestigeskala» nach Wegener, die Intelligenz mit dem Culture Fair Intelligenztest (CFT 20) und die subjektive Beurteilung mit einem selbst entwickelten Fragebogen erfasst. Ergebnisse: Im Mittel hat sich die Stichprobe um eine halbe Standardabweichung in der Rechtschreibleistung verbessert. Das Berufsprestige der Stichprobe liegt fast Dreiviertel über dem Durchschnittsbereich. Signifikante Auffälligkeiten hinsichtlich psychischer Symptome fanden sich nicht. Schlussfolgerung: Insgesamt ist die psychische und soziale Entwicklung der ehemaligen Internatsschüler sehr gut. In der Rechtschreibleistung liegt die Stichprobe im Mittel im unteren Durchschnittsbereich. Bei der Stichprobe können sowohl der hohe IQ, das hohe Berufsprestige der Väter und die lang andauernde Förderung sich positiv auf die Entwicklung ausgewirkt haben.

[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.

[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.

[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.

Das Marburger Rechtschreib-Training - Ergebnisse einer Kurzzeit-Intervention

Zusammenfassung Fragestellung: Das Marburger Rechtschreibtraining wurde mit einer Gruppe von 10 recht-schreibschwachen Grundschülern (2.-4. Klasse) über einen Zeitraum von drei Monaten als Einzeltraining durchgeführt. Ergebnisse: Dabei ergaben sich signifikante Verbesserungen im Rechtschreib- und Lesetest, jedoch noch nicht im subjektiv eingeschätzten Leidensdruck. Schlussfolgerung: Das Marburger Rechtschreibtraining hat sich nicht nur in einer Langzeit-, sondern auch in einer Kurzzeitintervention als erfolgreich herausgestellt.

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.

[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.

[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.

[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.

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.

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.

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.

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.

[The Marburg Parent-Child Spelling Trainer--follow up studies after 2 years]

The results of a two-year parent-child training program are reported. After one year of supervised tutoring by one of their parents, the children had only improved in those spelling areas that had been worked on in the program, otherwise there was no general improvement in their spelling ability. After the second year, not only their spelling ability in the specific areas had continued to increase, but their general spelling ability (spelling test percentile rank) had also improved. Their self-confidence had increased markedly as well. Significant predictors of the specific spelling improvement were the specific spelling ability at the initial measurement and whether or not the mother was working; significant predictors for the general improvement could not be found. Supervised tutoring by the parents was shown to be effective for improving childrens' spelling ability.

Role of auditory temporal processing for reading and spelling disability

The role of auditory temporal processing in reading and spelling was investigated in a sample of 30 children and one of 31 adults, using a gap-detection task with nonspeech stimuli. There was no evidence for a relationship between reading and spelling disability (dyslexia) and the gap-detection threshold. The results were discussed regarding the relevance for the popular hypothesis of an auditory temporal processing deficit underlying dyslexia.

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.

[The Marburg parent-child spelling training]

The first results of a parent-child program for improving the children's spelling are reported. Seventeen spelling-disabled children and their mothers took part for about one year in a supervised tutoring program that was based on German spelling rules. The parents met with two therapists one evening a month and received guidance with the program. Overall there was no improvement in spelling. However, a qualitative analysis of spelling errors revealed marked improvement in those areas that had been worked on in the program. Significant predictors of spelling improvement were the spelling ability of the mother and whether the mother was working or not.

Familial aggregation of spelling disability

This study examined the familial aggregation of spelling disability in a sample of 32 German school-aged children and their relatives. The influence of two different diagnostic criteria (low-achievement criterion, and regression-based IQ-discrepancy criterion) on the rate of affectedness was investigated. Results revealed that 52.3-61.9% of the sibs and 26-34% of the parents were spelling disabled. Little evidence was found for an influence of the diagnostic criterion on the rate of affectedness.

[Effect of an oligo-antigen diet on the behavior of hyperkinetic children]

The influence of an oligoantigenic diet on different dimensions of the behavior of 21 children diagnosed as having attention-deficit hyperactivity disorder (ADHD) was examined. Treatment effects were assessed with three subjective measures (two questionnaires and an interview) and three objective measures (two attention tests and actometer). The study was divided into three phases: baseline, diet and provocation, each lasting three weeks. A crossover design was used. A significant effect was found for the subjective measures, but not for the objective measures. The results are discussed in terms of possible types of effects, e. g. rater effects and environmental effects. It may be that the oligoantigenic diet influences only certain dimensions of hyperactivity.

Follow-up investigation of family relations in patients with anorexia nervosa

In a group of 22 formerly anorectic inpatients (follow-up 3.8 years after treatment) and in a control group of 24 paralleled young women, the subjective perception of the family structure was assessed using the "Subjective Family Image (SFI)", in order to investigate the question whether the family structure of former anorectics differs from the controls and whether individual development of the former inpatients is associated with the experienced family structure. Empirical results are in favor of the following two hypotheses: 1) Compared to the control group, formerly anorectic inpatients experience family relationships as more complicated and less satisfying. The quality of family relationships in the patient group is reduced, even at the time of follow-up. 2) Individual outcome (individual course of the illness) and quality of family relationships at time of follow-up are associated. Patients with a good outcome experience family relationships as more positive than patients with a poor outcome. The accordance of these findings to other empirical results and their implications for clinical practice are discussed.

[Reliability and validity of the German version of the Youth Self Report]

The aim of the present study was to investigate certain aspects of the reliability and validity of a German version of the Youth Self-Report (total behavior problem score) and to establish norms. In a sample of 252 patients from various child and adolescent psychiatric services and in an unselected sample of 1343 students from nearby schools high coefficients of internal consistency and split-half reliability (> 0.9) were obtained. An additional 105 students were tested and then retested after 5 weeks and again the rank correlations were high (boys: 0.86; girls: 0.90). The patients had higher total problem scores than the non-patients matched for age, sex, socioeconomic status, type of school and status as a foreigner. Patients with a diagnosis on axis 1 (psychiatric syndrome) or axis 5 (abnormal psychosocial situations) of the Multi-axial Classification Scheme were more maladjusted (higher total behavior problem score) than those without such a diagnosis. As expected, the score for the inpatients (N = 99) was higher than for the outpatients (N = 153). Because of the encouraging results, which justify further use of the Youth Self-Report, norms for the total behavior problem score (T-scores, percentiles) were calculated separately for the boys (N = 2085) and girls (N = 2119) from the general population (10-17 years of age).