Finn Egil Tønnessen

A new gene (DYX3) for dyslexia is located on chromosome 2

Developmental dyslexia is a specific reading disability affecting children and adults who otherwise possess normal intelligence, cognitive skills, and adequate schooling. Difficulties in spelling and reading may persist through adult life. Possible localisations of genes for dyslexia have been reported on chromosomes 15 (DYX1), 6p21.3-23 (DYX2), and 1p over the last 15 years. Only the localisation to 6p21.3-23 has been clearly confirmed and a genome search has not previously been carried out. We have investigated a large Norwegian family in which dyslexia is inherited as an autosomal dominant trait. A genome wide search for linkage with an average 20 cM marker density was initiated in 36 of the 80 family members. The linkage analysis was performed under three different diagnostic models. Linkage analysis in the family identified a region in 2p15-p16 which cosegregated with dyslexia. Maximum lod scores of 3.54, 2.92, and 4.32 for the three different diagnostic models were obtained. These results were confirmed by a non-parametric multipoint GENEHUNTER analysis in which the most likely placement of the gene was in a 4 cM interval between markers D2S2352 and D2S1337. Localisation of a gene for dyslexia to 2p15-16, together with the confirmed linkage to 6p21.3-23, constitute strong evidence for genetic heterogeneity in dyslexia. Since no gene for dyslexia has been isolated, little is known about the molecular processes involved. The isolation and molecular characterisation of this newly reported gene on chromosome 2 (DYX3) andDYX1 will thus provide new and exciting insights into the processes involved in reading and spelling.

Working Memory Deficit in Dyslexia: Behavioral and fMRI Evidence

ABSTRACT Dyslexia is a condition characterized by difficulty of reading given adequate intelligence and educational opportunities, primarily associated with a phonological processing deficit. In this study we show that dyslexic children also show a deficit in working memory compared to a control group, measured with fMRI. A working memory n-back task with three load levels was used. Behavioral data showed that the dyslexics had poorer performance compared to the controls. fMRI data showed that the dyslexics had reduced activation in the prefrontal and parietal cortices and the cerebellum compared with the controls. These results imply a working memory deficit in dyslexia.

Teacher training and teacher education in England and Norway: a comparative study of policy goals

In this paper, we examine the complementary and differing state‐defined roles of beginning schoolteachers in England and Norway by investigating centrally mandated initial teacher preparation programmes in both countries. Through comparative analysis, we get to see the roles that the policy‐makers in London and Oslo seek to confer upon the educators of future generations of schoolchildren, as well as exploring opportunities for cross‐cultural policy learning. In broad terms, we found that centrally prescribed initial teacher training in England is, as its name implies, a training model that seeks to induct trainee teachers into the practical skills and willingness necessary for: instructing pupils in National Curriculum subjects, managing classroom activities, setting homework to consolidate and extend classroom work and providing pupils with a safe learning environment. Centrally prescribed initial teacher education in Norway is, as its name implies, an educative model whose goal is to help student teachers to: reflect and act upon the practical implications of educational theory, instruct pupils in National Curriculum subjects, display leadership in the classroom, act as a member of a caring profession, promote Norwegian values and provide pupils with a safe learning environment.

Executive working memory processes in dyslexia: Behavioral and fMRI evidence

Dyslexia is an impairment in learning to read and write, primarily associated with a phonological core deficit. However, the manifestation of symptoms in dyslexia also includes impaired working memory (WM). The aim of this study was to investigate cortical activation related to verbal WM in dyslexic and normal readers aged around 13 years, controlling for phonological awareness processing. We used a modified WM n-back task where the participants remembered the first or last speech segment (phonemes) of the names of common objects shown as pictures. Dyslexic readers were impaired compared with the control group. Compared with the dyslexic readers, controls showed increased fMRI activation in the left superior parietal lobule and the right inferior prefrontal gyrus. Unlike controls, dyslexics did not show a significant increase in activation in WM areas with increased memory load. These findings provide support for a specific working memory deficit in dyslexic individuals.

How Can We Best Define ‘Dyslexia’?

Diverse needs and purposes determine the way ‘dyslexia’ is defined. Some traditional definitions are presented and discussed briefly. Some logical requirements for definitions are also presented and discussed briefly. The main aim of the article is to suggest guidelines and criteria for how we should formulate and evaluate definitions of ‘dyslexia’. A major conclusion is that proposed definitions should be formulated and treated as hypotheses.

Dyslexic children show short-term memory deficits in phonological storage and serial rehearsal: an fMRI study.

Dyslexia is primarily associated with a phonological processing deficit. However, the clinical manifestation also includes a reduced verbal working memory (WM) span. It is unclear whether this WM impairment is caused by the phonological deficit or a distinct WM deficit. The main aim of this study was to investigate neuronal activation related to phonological storage and rehearsal of serial order in WM in a sample of 13-year-old dyslexic children compared with age-matched nondyslexic children. A sequential verbal WM task with two tasks was used. In the Letter Probe task, the probe consisted of a single letter and the judgment was for the presence or absence of that letter in the prior sequence of six letters. In the Sequence Probe (SP) task, the probe consisted of all six letters and the judgment was for a match of their serial order with the temporal order in the prior sequence. Group analyses as well as single-subject analysis were performed with the statistical parametric mapping software SPM2. In the Letter Probe task, the dyslexic readers showed reduced activation in the left precentral gyrus (BA6) compared to control group. In the Sequence Probe task, the dyslexic readers showed reduced activation in the prefrontal cortex and the superior parietal cortex (BA7) compared to the control subjects. Our findings suggest that a verbal WM impairment in dyslexia involves an extended neural network including the prefrontal cortex and the superior parietal cortex. Reduced activation in the left BA6 in both the Letter Probe and Sequence Probe tasks may be caused by a deficit in phonological processing. However, reduced bilateral activation in the BA7 in the Sequence Probe task only could indicate a distinct working memory deficit in dyslexia associated with temporal order processing.

Motor regulation problems and pain in adults diagnosed with ADHD

BackgroundMost children who are diagnosed with attention deficit-hyperactivity disorder (ADHD) have moderate-to-severe motor problems using the Motor Function Neurological Assessment battery (MFNU). The MFNU focuses on specific muscle adjustment problems associated with ADHD, especially motor inhibition problems and high muscle tone. Here we investigated whether adults with ADHD/hyperkinetic disorder (HKD) have similar motor problems. In our clinical experience, adults with ADHD often complain about back, shoulder, hip, and leg pain. We also investigate reported pain in adults with ADHD.MethodsTwenty-five adult outpatients diagnosed with ADHD/HKD who were responders to methylphenidate (MPH) were compared to 23 non-ADHD controls on 16 MFNU subtests and using a ‘total score’ (‘TS’) parameter. The MFNU test leader was blinded to group identity. The two groups were also compared using the Pain Drawing and Numerical Pain Rating Scale.ResultsThe adult ADHD group had significantly (p < .001) more motor problems (higher TS) than controls. On the muscle regulation subtests, 36–96% of the ADHD group showed ‘moderate’ to ‘severe’ problems compared to 13–52% of the control group, and 80% of the ADHD group reported widespread pain. Highly significant differences were found between the ADHD and control groups for the variables ‘pain level’ (p < .001) and ‘pain location’ (p < .001). Significant correlations were found between TS and ‘pain location’ and between TS and ‘pain level’.ConclusionsThese findings suggest that similar to children with ADHD, adults diagnosed with ADHD also have motor inhibition problems and heightened muscle tone. The presence of significantly higher pain levels and more widespread pain in the ADHD group compared to non-ADHD controls might indicate that pain is a long-term secondary effect of heightened muscle tone and restricted movement that can be demonstrated in children and adults by the MFNU battery.

The relationship between phonological skills and word decoding

Word decoding ability is a critical factor in reading performance. In the present study, we examined the relationship between word decoding ability and three different phonological skills; phonemic awareness, verbal short-term memory (V-STM), and rapid automatic naming (RAN) in 1007 Scandinavian third- and fifth-graders. In the first part of the study, we sought to investigate the influence of the three phonological skills on word decoding ability. Using multiple regression analysis, our result clearly demonstrated that phonemic awareness was the most powerful phonological skill explaining variance in word decoding ability among average decoders. Among children with poor decoding skills, however, RAN was the most important factor in Grade 3, whereas V-STM was the main contributor to decoding ability among children in Grade 5. In the second part of the research, we examined the relationship between poor phonological skills and word decoding ability. Interestingly, our result revealed that approximately one half of the children with phonological difficulties, still performed within the average range with regard to word decoding ability. However, our analyses confirmed earlier research concerning the severe word decoding difficulties children with both poor phonemic awareness and restricted V-STM, experience.

Profiles of reading related skills in dyslexic families

The aim of the present study was to investigate patterns of similarity in reading related tasks among dyslexic members of the same family. From a sample of 19 well defined dyslexic students in grade 8, three cases were randomly selected for closer examination with a battery of tasks assumed to be causally related to reading. In all selected cases the fathers reported reading disability and in one case the mother was affected as well. The profiles of performance on the various tasks showed a striking similarity within families suggesting similar mechanisms underlying the reading disability. All cases showed remarkable problems in phonological processing, although functional reading skills were almost intact in some cases. Thus, the phonological tasks might be regarded as “marker tasks” for identifying genetic dyslexia.

Cascaded processing in written compound word production.

In this study we investigated the intricate interplay between central linguistic processing and peripheral motor processes during typewriting. Participants had to typewrite two-constituent (noun-noun) Finnish compounds in response to picture presentation while their typing behavior was registered. As dependent measures we used writing onset time to assess what processes were completed before writing and inter-key intervals to assess what processes were going on during writing. It was found that writing onset time was determined by whole word frequency rather than constituent frequencies, indicating that compound words are retrieved as whole orthographic units before writing is initiated. In addition, we found that the length of the first syllable also affects writing onset time, indicating that the first syllable is fully prepared before writing commences. The inter-key interval results showed that linguistic planning is not fully ready before writing, but cascades into the motor execution phase. More specifically, inter-key intervals were largest at syllable and morpheme boundaries, supporting the view that additional linguistic planning takes place at these boundaries. Bigram and trigram frequency also affected inter-key intervals with shorter intervals corresponding to higher frequencies. This can be explained by stronger memory traces for frequently co-occurring letter sequences in the motor memory for typewriting. These frequency effects were even larger in the second than in the first constituent, indicating that low-level motor memory starts to become more important during the course of writing compound words. We discuss our results in the light of current models of morphological processing and written word production.