Published papers

Nogo-N2 is associated with the premotor cognitive process that precedes motor response (e.g., conflict monitoring), whereas Nogo-P3 is related to the inhibition of the actual motor response. We examined the influence of motor clumsiness of developmental coordination disorder (DCD) on components of the event-related potential in a Go/Nogo task. Participants were healthy adults (N = 81) that were classified into control and DCD groups based on the Movement Assessment Battery for Children Second Edition. We manipulated the difficulty in stopping a response by varying the frequency of Nogo stimuli in a response task into rare (20%) and frequent (80%) conditions, and Nogo-N2 and Nogo-P3 were calculated from electroencephalograms (EEGs) during the Go/Nogo tasks. The commission error rate in the rare condition was significantly higher in the DCD group than in the control group, indicating that motor clumsiness decreases task performance. There were no differences in Nogo-N2 between DCD and control groups. However, Nogo-P3 in the rare condition was reduced in the DCD group compared to the control group. These results suggest that the influence of motor clumsiness is limited to the cognitive process after the initiation of the actual motor response.

We investigated the clinical symptoms of children with developmental dyslexia (DD) and evaluated the relationship between these symptoms and their Hiragana reading abilities. In order to detect the clinical symptoms of DD, we newly developed a clinical-symptoms-checklist (CL), which consisted of a total of 30 yes/no questions regarding symptoms linked to reading (15 questions) and writing (15 questions). Subjects were 98 Japanese school grade (1 to 9) children, aged 6 to 15 years old, with normal intelligence confirmed by the Wechsler Intelligence Test for Children (WISC-III) and they were divided into 2 groups according to their diagnosis. Twenty four children diagnosed as developmental dyslexia consisted the DD group, and the remaining 74 children were grouped in the non-DD group. CL showed significant construct validity (p< 0.05) and inner consistency (reading: α =0.82, writing: α =0.72) after deleting two questions from the originals. The number of questions checked in the CL reading subcategory significantly correlated with the Hiragana reading ability of articulation time in all Hiragana reading tasks (p< 0.001). More severe clinical symptoms and lower reading ability were observed in the DD group compared to the non-DD group. Receiver Operating Characteristics (ROC) analysis indicated that these two groups could be discriminated by the CL and the results of the reading task, and both sensitivity and specificity rate were approximately 80%. It was suggested that 7 or more positive checks in the CL and 2 or more abnormal scores in the reading tasks might discriminate DD from other conditions which cause difficulties in reading and writing in Japanese children.

OBJECTIVE: We aimed to clarify the strengths and weaknesses in adaptive behavior in children with focal epilepsy and show children-associated factors related to adaptive behavior. MATERIALS AND METHODS: Sixty-three children with focal epilepsy aged 5-18 years with intellectual quotient (IQ) ranging from 67 to 135 were enrolled in this study. Adaptive behavior was evaluated using the Vineland Adaptive Behavior Scale, 2nd edition (VABS-II). The children performed continuous performance test and tests of reading, writing, and IQ; parents answered questionnaires regarding attention-deficit hyperactivity disorder and autism spectrum disorder (ASD). Participants were categorized into four groups based on IQ and adaptive behavior scores for statistical comparisons. RESULTS AND DISCUSSION: Children with low adaptive behavior were more likely to show a reduction in daily living skills, and those with both low adaptive behavior and IQ were more likely to show a reduction in daily living skills and communication. Lower adaptive behavior was related to more severe autistic symptoms, lower academic achievement in children with IQ > 85, and lower executive function in children with IQ ≤ 85. There was a qualitative difference of cognitive dysfunction in adaptive behavior between both groups. CONCLUSIONS: There were differences in VABS-II domain and subdomain characteristics between children with focal epilepsy and those with ASD; however, it was more difficult for children with more severe ASD and coexisting focal epilepsy to show age-equivalent adaptive behavior.

This study investigated the applicability of the Movement Assessment Battery for Children - Second Edition (MABC-2) for 3- to 6-year-old Japanese children, particularly addressing its internal consistency and factorial validity. The MABC-2 test set for 3- to 6-year-old children was administered to 252 children. Differences between Japanese children and those of the original normative sample (i.e. United Kingdom children) were investigated along with sex differences. The Japanese children aged 3-6 years were found to have higher Manual Dexterity and Balance component scores than children of the normative sample. Girls scored higher than boys on the Balance component. Results of several analyses showed good internal consistency of the MABC-2. Confirmatory factor analysis revealed that a theoretical three-component model of the MABC-2 was not fitted to Japanese children aged 3-6 years. Instead, a new three-component model was postulated and discussed. The new three-component model of the MABC-2, with Manual Dexterity, Static Balance and Ball Skills, and Dynamic Balance, has high factorial validity in Japanese children aged 3-6 years.

Background: The diagnosis of Developmental Coordination Disorder (DCD) requires a precise assessment of motor skills via a standardized tool such as the Movement Assessment Battery for Children-Second Edition (MABC-2). Although the MABC-2 has been widely used in English-speaking countries, to the best of our knowledge, no studies have examined its applicability to Japanese children. Thus, it has been difficult to diagnose DCD in Japan. Aims: As a preliminary investigation preceding its formal standardization in Japan, we examined the applicability of the MABC-2. Methods and procedures: Participants comprised 132 typically developing Japanese children who completed a test set of the MABC-2 for Age Band 2. We analyzed both internal consistency and factorial validity for our Japanese sample. We also included a comparison between our sample of Japanese children and the normative sample of the MABC-2, as well as an examination of gender differences. Outcomes and results: Our results indicated acceptable internal consistency and scale homogeneity. High factorial validity, which has not been examined in other populations, was also confirmed for the test set. Moreover, we found differences in component scores between the Japanese and normative children with respect to Manual Dexterity and Balance. We also found that girls obtained superior Manual Dexterity and Balance scores compared with boys. Conclusions and Implications: The present findings represent the first step towards the standardization of the MABC-2 in a Japanese population. (C) 2016 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

Background: Shifting enables flexible switch between tasks or mental sets. It is a component of the executive function that plays critical roles in human behaviour control. However, shifting ability in individuals with intellectual disability (ID) has not been well clarified because of the use of intellectually demanding tasks in previous studies. The present study invented a novel shifting task with minimal intellectual demands and aimed to clarify the characteristics of shifting in adolescents with ID. Methods: Adolescents with ID (n = 21) and chronological-age-matched (n = 10) and mental-age-matched controls (n = 33) performed a novel shifting task with simple rule switching (i.e. change in direction). Analyses focused on the switch cost or the increase in the reaction time associated with rule switching. Results: Two subtypes of adolescents with ID were found with respect to the switch cost: one that lacks it and another with an increased switch cost. The lack of a switch cost was unique to the subgroup adolescents with ID and was not indicated in the control group. Conclusions: The present study indicated that shifting in adolescents with ID does not depend solely on their intellectual function and is highly heterogeneous. This finding further implies that executive functions, including shifting, must be evaluated separately from their intellectual functions.

BACKGROUND: Poor reading ability is one of the common causes of low academic performance. In previous studies, children with dyslexia were found to demonstrate poor academic achievement due to poor reading ability. However, the relationship between academic achievement and reading ability in children with a borderline full-scale intellectual quotient (FSIQ) is unknown. This study aimed to clarify the clinical characteristics of children with borderline FSIQ and poor reading ability, and differentiate these characteristics from those of children with higher FSIQ and poor reading ability. METHODS: A total of 126 children (aged 6-15 years) identified as having low academic performance were enrolled. The reading ability of children was assessed through their performance on the hiragana (Japanese syllabary) reading task, while their reading and writing achievement was assessed through their reading and writing score on the Kaufman Assessment Battery for Children, Second Edition. Children were categorized into two groups based on their FSIQ score (FSIQ > 85 and 85 ≥ FSIQ ≥ 70). Reading ability in children was evaluated by referring to the linear relationship between FSIQ and the standard deviation value of reading tasks in typically developing children. A one-way analysis of variance (ANOVA) was performed to examine clinical characteristics between higher and lower FSIQ groups. Associations between reading and writing achievement, reading ability, and ages of children were assessed using Pearson's product-moment correlation coefficients for the higher and lower FSIQ groups. RESULTS: Poorer reading and writing achievement was associated with poorer reading ability in the higher FSIQ group. Conversely, poorer reading and writing achievement and poor reading ability were associated with older age in the lower FSIQ group. CONCLUSIONS: Poor reading and writing achievement were associated with older age, not with poor reading ability in the lower FSIQ group. Children with lower FSIQ need appropriate educational interventions based on independent assessments to further their academic achievement and reading ability. Moreover, they need more frequent evaluations of their academic achievement than do children with higher FSIQ and poor reading ability since they are more likely to be at a lower academic achievement level at an older age.

Children with traits of developmental coordination disorder (DCD-t) may experience occupational performance problems that go unrecognized and therefore may not be adequately supported. The cognitive orientation to daily occupational performance (CO-OP) approach has been effective in interventions for developmental coordination disorder (DCD). Based on an open-label, randomized controlled trial design, this study evaluated the effects of CO-OP on the occupational performance and motor skills of older kindergarten children with DCD-t using the School Assessment of Motor and Process Skills (S-AMPS) and the Movement Assessment Battery for Children, Second Edition. Children with a total DCDQ score of less than 40 or M-ABC2 scores in the 5th to 16th percentile were considered to have DCD-t. Furthermore, children with DCD-t and S-AMPS process skills less than 0.7 were considered to have DAMP (Deficits in Attention, Motor control and Perception)-t. After 3 months of CO-OP intervention, the performance and motor skills of children with DCD-t improved significantly. However, there were no significant changes noted in the motor skills of children with DAMP-t, although their occupational performance improved. These results suggest that CO-OP is effective even for older kindergarten children with DCD-t. However, further improvement of the CO-OP approach or a different strategy is required for children with ADHD comorbidity.

Reading fluency is based on the automatic visual recognition of words. As a manifestation of the automatic processing of words, an automatic deviance detection of visual word stimuli can be observed in the early stages of visual recognition. To clarify whether this phenomenon occurs with Japanese kanji compounds—since their lexicality is related to semantic association—we investigated the brain response by utilizing three types of deviants: differences in font type, lexically correct or incorrect Japanese kanji compound words and pseudo-kanji characters modified from correct and incorrect compounds. We employed magnetoencephalography (MEG) to evaluate the spatiotemporal profiles of the related brain regions. The study included 22 adult native Japanese speakers (16 females). The abovementioned three kinds of stimuli containing 20% deviants were presented during the MEG measurement. Activity in the occipital pole region of the brain was observed upon the detection of font-type deviance within 250 ms of stimulus onset. Although no significant activity upon detecting lexically correct/incorrect kanji compounds or pseudo-kanji character deviations was observed, the activity in the posterior transverse region of the collateral sulcus (pCoS)—which is a fusiform neighboring area—was larger when detecting lexically correct kanji compounds than when detecting pseudo-kanji characters. Taken together, these results support the notion that the automatic detection of deviance in kanji compounds may be limited to a low-level feature, such as the stimulus stroke thickness.

Two hundred and seven Japanese elementary school children aged from 6 (Grade 1) to 12 (Grade 6) years old were tested for their abilities to name numbers and pictured objects along with reading Hiragana characters and words. These children all showed typical development and their classroom teachers judged that they were not having any problems with reading or writing. The children were randomly divided into two groups, the first group was assigned to two naming tasks the rapid automatized naming (RAN) of "numbers" and "pictured objects," the second group was assigned to two rapid alternative stimulus (RAS) naming tasks using numbers and pictured objects. All children were asked to perform two reading tasks that were written in Hiragana script : single mora reading task and four syllable word reading task. The total articulation time for naming and reading and performance in terms of accuracy were measured for each task. Developmental changes in these variables were evaluated. The articulation time was significantly longer for the first graders, and it gradually shortened as they moved through to the upper grades in all tasks. The articulation time reached a plateau in the 5th grade for the number naming, while gradual change continued after drastic change in the lower grades for the pictured object naming. The articulation times for the single mora reading and RAN of numbers correlated strongly. The articulation time for the RAS naming was significantly longer compared to that for the RAN, though there were very few errors. The RAS naming showed the highest correlation with the four syllable word reading. This study demonstrated that the performance in rapid automatized naming of numbers and pictures were closely related with performance on reading tasks. Thus Japanese children with reading disorders such as developmental dyslexia should also be evaluated for rapid automatized naming.

BACKGROUND: Children with Williams syndrome (WS) show a marked interest in music, a characteristic often explored in clinical settings. However, the actual musical abilities of patients with WS remain debatable due to some of the relevant data being derived from experimental tasks that require a verbal response, despite the known language impairments in WS. The present study aimed to examine musical ability in children with WS using a newly invented pitch discrimination task with minimal involvement of language and clarify its relationship with language skill. METHODS: Eleven children with WS participated in the study. We used a novel pitch discrimination task that required minimal language use. Two piano tones were presented sequentially, and children were asked to give a non-verbal response as to whether the second tone was higher than, lower than, or the same as the first tone. RESULTS: Pitch discrimination performance in children with WS was lower than the level predicted for their chronological age (CA), even in the non-verbal task. Pitch discrimination ability and verbal mental age (VMA) were shown to be dissociated, such that children with WS with a lower skill level for language showed an unexpectedly higher level of pitch discrimination ability and vice versa. CONCLUSIONS: Our results indicated reduced musical ability with respect to CA in children with WS. The dissociation between musical ability and language skills may indicate unique developmental relationships that differ from those in normal children. These findings provide new evidence to support the importance of assessing actual musical ability in WS prior to implementing interventional music therapy.

AIMS: Patients with attention-deficit hyperactivity disorder (ADHD) often exhibit basic or paroxysmal wave abnormalities on electroencephalography (EEG). Methylphenidate (MPH), an anti-ADHD stimulant, has been reported to lower the seizure threshold. However, there have been no reports comparing EEG changes before and after administration of the central nervous system (CNS) stimulant MPH, or atomoxetine (ATX) hydrochloride, a non-CNS stimulant. In this study, we investigated changes in sleep EEG before and after the administration of ADHD treatment drugs. METHOD: With the approval of the ethics committee, the medical records of 28 children with ADHD (23 men and 5 women) who gave consent were retrospectively investigated. The appearance of sudden abnormal waves during a 10-minute sleep EEG recording was measured in 0.1-second units, and the duration of these waves was calculated as the paroxysmal index (PI). RESULTS: Paroxysmal index did not differ significantly between patients who received MPH and those who received ATX. In addition, there were no exacerbations of clinical seizures. CONCLUSION: It was concluded that ADHD medications do not have an adverse effect on epileptic seizures or abnormal sleep EEGs.

The current study sought to develop a new behavioral analysis methods to evaluate the effects of social skills training (SST). SST is known to be an effective method to improve the social skills of children with behavioral problems. However, current evaluation methods involve behavioral rating scales that are heavily dependent on evaluators' particular experiences they have had. To quantitatively examine the behavioral effects of SST, we examined subjects' head-movements related to social behavior, using a two-dimensional motion capture system (Kissei Comtec, Japan). Four children (three male, one female, 7-8 years of age) with pervasive developmental disorder (PDD) or attention deficit/hyperactivity disorder (AD/HD) participated in 16 sessions of SST. Before and after SST, head-coordinates on a two-dimensional plane were calculated using their behavior during a pair task, measured by four digital cameras. After SST, the number of communication behaviors was increased compared to before SST. In addition, children looked longer at another child within 30 degrees of the central visual field. Time-series analysis of the visual field during the detection of another child revealed significant auto-correlation from about - 1.12 second, before to the beginning of communication behavior (p< 0.05). The results suggested mat our method can provide a quantitative index of characteristics related to skilled social behaviors. We conclude mat a two-dimensional motion capture system would be useful for visualization of the interventional effects of SST, which would supplement assessments by the conventional observational strategies.

This study examined the effects of a rich, emotionally-satisfying childbirth experience (CBE) of mothers on the behavior of school-age children using longitudinal data measured from immediately to 7 years and 6 months after birth. The results of structural equation modeling revealed the following: 1) giving birth in a midwifery center enhances emotional satisfaction with CBE, 2) a rich CBE of mothers was associated with parental warmth, 3) parental warmth during early childhood increased prosocial behavior and reduced behavioral problems in school-age children, and 4) temperamentally difficulty in early childhood were linked to later behavioral problems in school-age children. Thus, a rich CBE and parental warmth were suggested to be factors contributing to the good behavior of school-age children.