Published papers

Although phonics is the most frequently used approach in treating students with reading difficulties, its effects have not been fully clarified at either a behavioral or neurophysiological level. The present case study administered pure and short-term (i.e., 10minutes per day for five weeks) phonics-training to a 13-year-old Japanese girl with severe difficulty in learning English. As a result, a drastic improvement in reading accuracy was associated with the enhancement of print-specific N170 in event-related potentials (ERPs) elicited by the trained words. The present finding indicates that phonics training can, by itself, remediate English reading and affect its neurophysiological bases.

Objective: Developmental dyslexia (DD) is a neurodevelopmental disorder that is characterized by difficulties with accurate and/or fluent word recognition and by poor spelling and decoding abilities. The magnocellular deficit theory is one of several hypotheses that have been proposed to explain the pathophysiology of DD. In this study, we investigated magnocellular system dysfunction in Japanese dyslexic children. Methods: Subjects were 19 dyslexic children (DD group) and 19 aged-matched healthy children (TD group). They were aged between 7 and 16 years. Reversed patterns of black and white sinusoidal gratings generated at a low spatial frequency, high reversal frequency of 7.5 Hz, and low contrasts were used specifically to stimulate the magnocellular system. We recorded visual evoked potentials (VEP) from the occipital area and examined their relationship with reading and naming tasks, such as the time to read hiragana characters, rapid automatized naming of pictured objects, and phonological manipulation. Results: Compared to the TD group, the DD group showed a significantly lower peak amplitude of VEPs through the complex demodulation method. Structural equation modeling showed that VEP peak amplitudes were related to the rapid automatized naming of pictured objects, and better rapid automatized naming resulted in higher reading skills. There was no correlation between VEP findings and the capacity for phonological manipulation. Conclusions: VEPs in response to the magnocellular system are useful for understanding the pathophysiology of DD. Single phonological deficit may not be sufficient to cause DD.

Patients with major depressive disorder (MDD) exhibit several clinical symptoms including difficulties in flexible thinking. Flexible thinking mainly relies on a cognitive ability called shifting; however, the mechanisms underlying shifting in patients with MDD have not yet been clarified. Therefore, we conducted a preliminary intervention study to clarify the association between depression and shifting ability. We examined the hemodynamic responses in the frontal regions during the shifting task using functional near-infrared spectroscopy (fNIRS) in 21 patients with MDD who were treated using high-frequency repetitive transcranial magnetic stimulation (rTMS). Behavioral performance on the shifting task did not change between pre- and posttreatments, whereas patients who responded well to rTMS treatment showed a significant decrease in hemodynamic responses posttreatment. On the other hand, the poor responders did not show significant changes in the hemodynamic responses between pre- and posttreatments. These results suggest that the good responders were successfully remedied with rTMS treatment and did not need effortful activity in frontal regions for shifting, which made their brain activity more efficient.

Objective: The right prefrontal cortex (PFC) plays an essential role in active processing within visuospatial working memory (VSWM). The aim of this study was to examine developmental changes in the recruitment patterns of the PFC during visuospatial memory tasks in school-age participants. Methods: We recruited 80 school-age children who were classified into three age groups: 7- to 8-year-old, 9- to 10-year-old, and 11- to 12-year-old children. We used near infrared spectroscopy (NIRS) to measure PFC activity during visuospatial memory task. Memory stimuli were presented either sequentially or simultaneously. Results: In all three groups, right-lateralized PFC activity was observed during sequential presentation, suggesting specialization of the right PFC for VSWM. During simultaneous presentation, right-lateralized PFC activity was not observed in 7- to 8-year-old children or 9- to 10-year-old children. In contrast, PFC activity was right-lateralized in 11- to 12-year-old children. Conclusions: We suggest that specialization of the right PFC for VSWM is already present before school-age, but widely distributed activity in response to visuospatial memory tasks changes to more focal activity in VSWM-specific regions during the early school years. Significance: Using NIRS, we showed developmental changes in the recruitment patterns of the PFC during visuospatial memory tasks.

Objective:While the Hiragana reading test is essential for the diagnosis and treatment of developmental dyslexia in Japan, the current norm may overdiagnose reading difficulties, especially among lower graders. The present study aimed to verify the current norm and the extent of overdiagnosis based on a large sample of first graders(G1)and second graders(G2). In addition, more appropriate norm was explored using longitudinal data. Methods:A total of 511 and 422 students enrolled in G1 and G2 at public elementary schools, respectively, completed the Hiragana reading test. First, we compared the reading time distributions between the present sample and the current norm. Second, the diagnosis rate of reading difficulty was examined for each grade. Finally, a new norm was established for the Hiragana reading test based on a three-year longitudinal data, which were contrasted with the current norm with respect to diagnosis rate and longitudinal trajectory. Results:Reading times in the present G1 and G2 samples were considerably longer than the current norm. Diagnosis rate of reading difficulty reached as high as 47.0% in G1 and 30.3% in G2. The longitudinally established new norm was more moderate and led to diagnosis rate of around 7% for both grades. In a comparison of three-year trajectory, nearly half of the students were classified as having reading difficulties, at least once based on the current norm, whereas the use of new norm dropped the classification rate to around 15% and improved overdiagnosis. Conclusions:The current norm of the Hiragana reading test was overly strict for both G1 and G2 graders, which indicates that there is a high risk of overdiagnosing reading difficulties. The new norm was suggested to be more useful for both medical diagnosis and educational intervention. Therefore, it is necessary to modify grade norms of the Hiragana reading test.

Introduction: In Western countries, reading disorders are believed to be caused by phonological processing problems. Conversely, Japanese children with developmental dyslexia (DD) and developmental dysgraphia often have difficulty learning kanji that are ideographic characters. It is believed that kanji learning and alphabet learning have different pathologies, as the latter uses phonetic character. In this study, we aimed to clarify the characteristics of kanji word recognition in Japanese children with DD and developmental dysgraphia using magnetoencephalography with high spatial resolution. Methods: Seven Japanese children with learning disorders, including 4 with DD and 3 with developmental dysgraphia, and 14 typically developing Japanese children (TDC) underwent magnetoencephalography while presented with kanji compounds and pseudo-kanji character sequences in their parafoveal visual fields, along with a foveal silent movie. Results: No differences were found between conditions or groups, except significantly smaller source activation in the posterior transverse region of the collateral sulcus (ptCoS) in the patient group, when presenting pseudo-kanji than presenting kanji, or than TDC when presenting deviant pseudo-kanji. The ptCoS activity from kanji exhibited a positive correlation with writing skills in the patient group, independently of attention deficit hyperactivity disorder (ADHD) symptom scores. Conclusions: These results suggest that ptCoS activity during the presentation of kanji characters in Japanese children with DD and developmental dysgraphia reflects their writing ability, regardless of ADHD symptoms. Some forms of ptCoS dysfunction may be related to the neural basis of specific kanji writing functions in Japanese patients with DD and developmental dysgraphia.

Because of unique linguistic characteristics, the prevalence rate of developmental dyslexia is relatively low in the Japanese language. Paradoxically, Japanese children have serious difficulty analysing phonological processes when they have dyslexia. Neurobiological deficits in Japanese dyslexia remain unclear and need to be identified, and may lead to better understanding of the commonality and diversity in the disorder among different linguistic systems. The present study investigated brain activity that underlies deficits in phonological awareness in Japanese dyslexic children using functional magnetic resonance imaging. We developed and conducted a phonological manipulation task to extract phonological processing skills and to minimize the influence of auditory working memory on healthy adults, typically developing children, and dyslexic children. Current experiments revealed that several brain regions participated in manipulating the phonological information including left inferior and middle frontal gyrus, left superior temporal gyrus, and bilateral basal ganglia. Moreover, dyslexic children showed altered activity in two brain regions. They showed hyperactivity in the basal ganglia compared with the two other groups, which reflects inefficient phonological processing. Hypoactivity in the left superior temporal gyrus was also found, suggesting difficulty in composing and processing phonological information. The altered brain activity shares similarity with those of dyslexic children in countries speaking alphabetical languages, but disparity also occurs between these two populations. These are initial findings concerning the neurobiological impairments in dyslexic Japanese children.

Objective: Reading and writing difficulties in children with a multilingual background are often considered to be a consequence of limited language proficiency rather than developmental dyslexia (DD) or intellectual disabilities. However, since these latter conditions are also prevalent in a multilingual population, the present study explored the assessment and diagnosis of DD. through a case-series study of Japa-nese-English bilingual children. Methods: The participants were four school-aged Japanese-English bilingual children (Cases 1-4) with reading and writing difficulties as a major complaint. They were tested for cognitive abilities (IQ) and both oral language and basic literacy skills in Japanese and English, and we made a diagnosis of a specific learning disorder based on DSM-5. Results: Full-scale IQ and oral language abilities in both Japanese and English were within the normal range for all cases. Regarding basic literacy skills, three of them (' nr 1, 3, 4) showed difficulties from the level of Hiragana reading while one (Case 2) showed difficulties in kanji. Two children who used English at school also showed severe difficulties in alphabet naming (Case 3) and oral text reading (Cases 3, 4). Based on these res«,us, Cases 1, 3, and 4 were diagnosed as having a specific learning disorder in both reading and writing, while Case 2 was diagnosed as ha + disorder mainly in writing. Conclusions: The evaluation of basic literacy skills (e. g., letter, word, and simple text reading) were shown to be particularly useful for assessing DD in multilingual children. While assessment and diagnosis in similar cases that involve multipl-guages pose many challenges in practice, approaches that can be used to identify innate specific learning disorders despite the complex environmental and linguistic background are needed.

Although atypical processing of biological motion (BM) in individuals with autism spectrum disorder (ASD) has been reported, the temporal profile of the neural response to BM is not well explored. In the current study, event-related potentials (ERPs) were measured in 12 individuals with ASD, aged 8-22 years, and 12 age- and gender-matched normal controls, to investigate the electrophysiological response to BM and a control visual stimulus. By introducing a novel experimental paradigm that can dissociate the electrophysiological responses to motion processing and the global shape processing of BM, we found that: (1) the timing of the response was preserved in ASD groups, whereas (2) the ERP response to BM was significantly enhanced compared with scrambled point-light motion (SM) in normal controls; the responses to both BM and SM were not significantly different in subjects with ASD. Because we did not find a significant group effect on the peak and mean amplitude induced by BM, it is presumed that this atypical response in individuals with ASD was due to over-sensitivity to the local motion signals. This experimental paradigm showed atypical local motion processing of BM in individuals with ASD. (C) 2014 Elsevier Ltd. All rights reserved.

Increased risk of injury from collisions with objects is an important issue in children with autism spectrum disorder (ASD). The purpose of the present study was to examine whether impaired perceptual-motor coordination may underlie the high frequency of collisions. Specifically, we hypothesized that collisions are likely to occur frequently in children with ASD due to their difficulty with body-related spatial perception and their inadequate motor planning, due to their detail-focused processing style, i.e., a tendency to focus attention on specific details rather than on the overall context. To evaluate impairment of perceptual-motor coordination in children with ASD, an original action selection task was developed to assess (a) body-related spatial perception and (b) predictive attentional properties for planning the subsequent movements based on the measures of hand movement and gaze behavior. Twenty-six children (13 diagnosed as ASD and 13 with typical development [TD]) completed the task, and their parents completed a questionnaire regarding their child's susceptibility to injury. Results showed that children with ASD displayed inaccurate body-related spatial perception and inadequate motor planning under conditions that induced their detail-focused processing style. In addition, analyses of gaze behavior reflected the characteristics of a detail-focused processing in children with ASD. This was correlated with the severity of ASD and the measure of motor planning. The present findings suggest that difficulty with perceptual-motor coordination, resulting in part from the detail-focused processing style, might contribute to susceptibility to injury in children with ASD. We consider that our evaluation of the difficulty with perceptual-motor of individuals with ASD provides a framework for understanding their high rate of collision-related injuries and could inform strategies for preventing these injuries.

In this study, we aimed to investigate the cognitive and affective-emotional factors underlying math achievement in a sample of 169 Japanese elementary school children. Using structural equation modeling, we examined the contributions of fluid and crystallized intelligence, verbal and spatial working memory, and affective-emotional variables, including general anxiety, test anxiety, math anxiety, and math self-efficacy. We found intelligence to be a strong positive predictor of math achievement, while among the affective-emotional variables, math self-efficacy emerged as the only significant predictor of math achievement. Interestingly, intelligence mediated the association between affective-emotional factors, such as math anxiety and self-efficacy, highlighting its central role in children’s math achievement. These findings underscore the strong relationship between intelligence and self-efficacy in educational contexts, suggesting that self-efficacy is closely linked to cognitive abilities to support children’s success in math. Educational implications are discussed, emphasizing the need to strengthen math self-efficacy alongside cognitive abilities.

We investigated the effects of social interaction and out-of-class study time on foreign language proficiency and use among two hundred students from a Japanese university who studied abroad for one month. Participants’ use of English and English proficiency were measured before and after the programme. Interaction with people from other cultures and out-of-class study time while abroad were also reported. Based on social interaction and out-of-class study time, students were grouped into four clusters: an Unengaged cluster, with low levels of interaction and out-of-class study time; a Balanced cluster, with average levels of both interaction and study time; a Studious cluster, with high out-of-class study time but low interaction levels; and a Communicative cluster, with high interaction levels but low study time. Analyses of clusters’ main effects revealed that overall, the Studious group had higher English proficiency, and the Balanced and Communicative groups reported higher use of English than the Unengaged group. While English proficiency increased to the same degree in all four groups, the Balanced group gained more in English use compared to the Unengaged group after study abroad. The results suggest the importance of how students spend their time abroad in promoting foreign language use.

Maintaining students’ learning engagement was a challenge in emergency online education during the pandemic. In this study, we investigated the predictors (social interaction) and outcomes (self-directed study) of engagement in online learning during the first and second years of the COVID-19 pandemic. First-year Japanese university students (N = 1167) enrolled in online classes during 2020 and 2021 responded to a questionnaire measuring perceived opportunities for social interaction during online classes, engagement with online learning, and extracurricular self-directed study time. Multi-group path analysis revealed that social interaction during online classes exhibited a positive indirect effect on self-directed study time through emotional and behavioral engagement with online learning. The positive indirect effect was significant in both the first and second years of the pandemic. The results suggest that increasing the number of opportunities for social interaction during online classes may exhibit spillover effects on learning outside the online classroom.

Balanced chromosomal translocation is one of chromosomal variations. Carriers of balanced chromosomal translocations have an increased risk of spontaneous miscarriage. To avoid the risk, preimplantation genetic testing (PGT) using comprehensive genomic copy number analysis has been developed. This study aimed to verify whether and how embryos from couples in which one partner is a balanced translocation carrier have a higher ratio of chromosomal abnormalities. A total of 894 biopsied trophectoderms (TEs) were obtained from 130 couples in which one partner was a balanced translocation carrier (Robertsonian translocation, reciprocal translocation, or intrachromosomal inversion) and grouped as PGT-SR. Conversely, 3269 TEs from 697 couples who experienced recurrent implantation failure or recurrent pregnancy loss were included in the PGT-A group. The transferable blastocyst ratio was significantly lower in the PGT-SR group, even when bias related to the sample number and patient age was corrected. Subgroup analysis of the PGT-SR group revealed that the transferable blastocyst ratio was higher in the Robertsonian translocation group. Because the PGT-SR group had a higher proportion of untransferable embryos than the PGT-A group, PGT using comprehensive genomic copy number analysis was more beneficial for balanced translocation carriers than for infertility patients without chromosomal translocations. The frequencies of de novo aneuploidies were further analyzed, and the frequency in the PGT-SR group was lower than that in the PGT-A group. Therefore, we could not confirm the existence of interchromosomal effects in this study.

There is a host of research on the structure of working memory (WM) and its relationship with intelligence in adults, but only a few studies have involved children. In this paper, several different WM models were tested on 170 Japanese school children (from 7 years and 5 months to 11 years and 6 months). Results showed that a model distinguishing between modalities (i.e., verbal and spatial WM) fitted the data well and was therefore selected. Notably, a bi-factor model distinguishing between modalities, but also including a common WM factor, presented with a very good fit, but was less parsimonious. Subsequently, we tested the predictive power of the verbal and spatial WM factors on fluid and crystallized intelligence. Results indicated that the shared contribution of WM explained the largest portion of variance of fluid intelligence, with verbal and spatial WM independently explaining a residual portion of the variance. Concerning crystallized intelligence, however, verbal WM explained the largest portion of the variance, with the joint contribution of verbal and spatial WM explaining the residual part. The distinction between verbal and spatial WM could be important in clinical settings (e.g., children with atypical development might struggle selectively on some WM components) and in school settings (e.g., verbal and spatial WM might be differently implicated in mathematical achievement).

Background: Motor skills have been linked to executive functions (EFs) in children with developmental coordination disorder (DCD). However, the traits of other neurodevelopmental disorders (NDDs), such as attention-deficit/hyperactivity disorder and autism spectrum disorder, remain overlooked. Therefore, this study explored the association between motor skills, occupational performance, and mental health in older kindergarten children with DCD and other NDDs. Overall, 95 participants aged 5–6 years were included in this study and divided into four groups: DCD traits (DCD-t), DCD-t + NDD traits (DCD-t + NDD-t), NDD-t-only, and typically developing children. Motor skills, EFs, and mental health were assessed using the DCD Questionnaire (DCDQ-J) and Movement Assessment Battery for Children—Second Edition, School Assessment of Motor and Process Skills (S-AMPS), and the Strengths and Difficulties Questionnaire (SDQ), respectively. The DCD-t + NDD-t group exhibited a strong correlation between the S-AMPS motor skill score and the DCDQ-J fine motor skill score (r = 0.88, p < 0.001) and between the total DCDQ-J score and the SDQ Total Difficulties Score (r = −0.94, p < 0.001). The findings indicate that children with DCD-t and NDD-t are more likely to experience EF and mental health problems than those with DCD-t only.