Abnormality in GABAergic postsynaptic transmission associated with anxiety in Bronx waltzer mice with an Srrm4 mutation.

The homozygous Bronx waltzer (bv) mouse, which shows hearing impairment, also exhibits anxiety accompanied by a reduction in cortical parvalbumin (PV)-positive GABAergic interneurons. Recently, a mutation in splicing factor Ser/Arg repetitive matrix 4 (Srrm4) was found in bv mice. However, the cellular consequences of the Srrm4 mutation for anxiety remain unknown. Here, we tested our hypothesis that bv mutant primarily affects interneurons through a cell-intrinsic pathology that leads to a reduction of interneurons and consequently causes anxiety. We found that the anxiety becomes apparent at 6 weeks of age in bv/bv mice. However, in situ hybridization revealed that Srrm4 is not expressed in interneurons, but rather dominates in pyramidal neurons. In addition, the PV-positive GABAergic interneurons were not reduced in number in the bv/bv cortex when anxiety became evident. However, electrophysiological abnormality of GABAergic transmission from interneurons was concomitantly present. Pharmacological blockage of GABAA receptors revealed increased excitability in bv/bv mice, although no gross change occurred in the expression of an Srrm4-downstream gene, Kcc2, which regulates chloride flux upon GABAergic transmission. These findings suggest that the bv-associated Srrm4 mutation mainly involves post-synaptic GABAergic transmission in the central nervous system, which may be associated with the anxiety phenotype in bv/bv mice.

Modulation effects of the intact motor skills on the relationship between social skills and motion perceptions in children with autism spectrum disorder: A pilot study.

BACKGROUND: An individual with autism spectrum disorder (ASD) has social skill, motor skill, and motion perception deficits. However, the relationship among them was not clarified. Therefore, this study aimed to evaluate the effects of motor skills on social skills and motion perception. METHODS: Five typically developed children and fourteen children with ASD participated in our study. The N200 component, a brain activity indicating motion perception, was induced in mid-temporal (MT/V5) brain area by watching a random dot kinematograph, and was recorded using a scalp electroencephalogram. Furthermore, the social responsiveness scale (SRS) indicating the social skill deficit, the developmental coordination disorder questionnaire (DCDQ) estimating the developmental coordination disorder (DCD), and the movement assessment battery for children second edition (MABC-2) indicating motor skills were recorded in the children with ASD. A hierarchical multiple regression analysis was conducted to examine the modulation effects of motor skills on the relationship between social skills and motion perception. The dependent variable was the N200 latency, and the independent variables were SRS, MABC-2, and combined MABC-2 and SRS. RESULTS: The N200 latency was more delayed in children with ASD relative that in typically developed children. Intact balance ability modulated the relationship between social skills and N200 latency in children with ASD. Within the high balance ability, when the social skills worsened, the N200 latency was shortened. CONCLUSIONS: This is the first report that intact motor skills could modulate the relationship between social skills and motion perception.

Detection of deviance in Japanese kanji compound words.

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.

Effect of anti-attention-deficit hyperactivity disorder (ADHD) medication on clinical seizures and sleep EEG: A retrospective study of Japanese children with ADHD.

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.

Clinical profile of reading ability and reading and writing achievement of children with borderline full-scale intellectual quotient: a prospective study.

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.

The Relationships Among Autism Spectrum Disorder Traits, Loneliness, and Social Networking Service Use in College Students.

This study aimed to explore the relationships among autism spectrum disorder (ASD) traits, loneliness, and social networking services (SNS) use. We created a questionnaire to evaluate manners during LINE use, which included five factors: "low literacy," "inactive use," "low responsiveness," "lack of consideration," and "low group activity." Structural equation modeling revealed that difficulties in attention switching and low communication skills were associated with low literacy, low social skills were associated with inactive use, and low literacy and inactive use were associated with loneliness. We suggested that SNS use plays a role in maintaining and enhancing friendships, whereas college students with higher ASD traits tend to use inappropriate manners for SNS, which is associated with loneliness.

Postoperative improvement of executive function and adaptive behavior in children with intractable epilepsy.

INTRODUCTION: An alteration in postoperative cognitive function varies according to the patients' background characteristics, such as etiology, focus, and seizure duration. Accurate prediction and assessment of postoperative cognitive function is difficult in each patient. Adaptive behavior could describe the typical performance of daily activities and represents the ability to translate cognitive potential into real-world skills. We examined the relationship between alterations of executive function (EF) and adaptive behavior in school children undergoing surgery for intractable epilepsy. METHODOLOGY: We enrolled 31 children with focal resection or corpus callosotomy for intractable epilepsy [mean age at surgery, 12.5 years; 16 boys; mean intellectual quotient, 73.3]. We surveyed answered questionnaires on attention-deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD), and adaptive behavior using the Vineland Adaptive Behavior Scale, 2nd edition (VABS-II), and performed continuous performance tests (CPTs) on children pre- and postoperatively. RESULT: ADHD and ASD symptoms improved after epilepsy surgery. The omission error (OE) in the CPT variable improved after epilepsy surgery, especially in children with a shorter preoperative period. Improved ASD symptoms led to an increased score of the coping skills subdomain. The reduced OE observed after surgery also increased the score of the community skills subdomain. CONCLUSION: Improvement in EF and ASD symptoms resulted in better adaptive behavior postoperatively. These results were important for the pre- and postoperative evaluation and re-evaluation of children with epilepsy requiring special education and related services.

Association between lack of functional connectivity of the frontal brain region and poor response inhibition in children with frontal lobe epilepsy.

PURPOSE: We investigated the relationship between electroencephalographic (EEG) functional connectivity and executive function in children with frontal lobe epilepsy (FLE). METHODS: We enrolled 24 children with FLE (mean age, 11.0 years; 13 boys) and 22 sex-, age-, and intelligence-matched typically developing children (TDC) to undergo 19-channel EEG during light sleep. We estimated functional connectivity using the phase lag index (PLI) that captures the synchronization of EEG. We also performed continuous performance tests (CPTs) on the children and obtained questionnaire responses on attention deficit hyperactivity disorder and oppositional defiant disorder (ODD). RESULTS: The average gamma PLI was lower in the FLE group than in the TDC group, especially between long-distance frontoparietal pairs, between interhemispheric frontal pairs, and between interhemispheric parietotemporal pairs. Gamma PLIs with long-distance frontoparietal and interhemispheric frontal pairs were positively associated with inattention, ODD scores, omission error, and reaction time in the FLE group but not in the TDC group. Conversely, they were negatively associated with age, hyperactivity score, and commission error. CONCLUSIONS: A lack of functional connectivity of the frontal brain regions in children with FLE was associated with poor response inhibition.

Executive dysfunction in medication-naïve children with ADHD: A multi-modal fNIRS and EEG study.

OBJECTIVE: Children with attention deficit hyperactivity disorder (ADHD) exhibit deficits in executive function. Since there are no clear biomarkers for the disorder, this study aimed to investigate the neurophysiological biomarkers for deficits in executive function in children with ADHD using functional near-infrared spectroscopy (fNIRS) and electroencephalography. METHODS: Twenty patients diagnosed with ADHD and 19 typically developing children (TDC; 8-11 years old) were included. Event related potentials (ERPs) were recorded using an electroencephalogram (EEG) and oxygenated hemoglobin concentrations (Oxy-Hb) were recorded using fNIRS during a colored Go/NoGo task, simultaneously. Latencies and amplitudes of NoGo-N2 and NoGo/Go-P3 tasks were measured using EEG. RESULTS: Children with ADHD showed significantly decreased Oxy-Hb in the right frontal cortex as well as longer NoGo-P3 latencies and a decreased NoGo/Go-P3 amplitude. There was a significant positive correlation between the Oxy-Hb and NoGo/Go-P3 amplitude. CONCLUSIONS: These results suggest that children with ADHD experience executive dysfunction. Hemodynamic and electrophysiological findings during the Go/NoGo task might be useful as a biomarker of executive function. SIGNIFICANCE: These findings have key implications for understanding the pathophysiology of deficits in executive function in ADHD.

Adaptive behavior and its related factors in children with focal epilepsy.

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.

Reduced Nogo-P3 in adults with developmental coordination disorder (DCD).

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.

Timing of phase-amplitude coupling is essential for neuronal and functional maturation of audiovisual integration in adolescents.

OBJECTIVE: The ability to integrate audiovisual information matures late in adolescents, but its neuronal mechanism is still unknown. Recent studies showed that phase-amplitude coupling (PAC) of neuronal oscillations, which is defined as the modulation of high-frequency amplitude by low-frequency phase, is associated with audiovisual integration in adults. Thus, we investigated how PAC develops in adolescents and whether it is related to the functional maturation of audiovisual integration. In particular, we focused on the timing of PAC (or the coupling phase), which is defined as the low-frequency phase with maximum high-frequency amplitude. METHODS: Using magnetoencephalography (MEG) on 15 adults and 14 adolescents while they performed an audiovisual speech integration task, we examined PAC in association cortexes with a trial-by-trial analysis. RESULTS: Whereas delta-beta coupling was consistently observed in both adults and adolescents, we found that the timing of delta-beta PAC was delayed by 20-40 milliseconds in adolescents compared with adults. In addition, a logistic regression analysis revealed that the task performance improves as the timing of delta-beta PAC in the right temporal pole (TP) got closer to the trough position (180 degrees). CONCLUSION: These results suggest that the timing of PAC is essential for binding audiovisual information and underlies the developmental process in adolescents.

Discrepancy between musical ability and language skills in children with Williams syndrome.

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.

Applied Machine Learning Method to Predict Children With ADHD Using Prefrontal Cortex Activity: A Multicenter Study in Japan.

Objective: To establish valid, objective biomarkers for ADHD using machine learning. Method: Machine learning was used to predict disorder severity from new brain function data, using a support vector machine (SVM). A multicenter approach was used to collect data for machine learning training, including behavioral and physiological indicators, age, and reverse Stroop task (RST) data from 108 children with ADHD and 108 typically developing (TD) children. Near-infrared spectroscopy (NIRS) was used to quantify change in prefrontal cortex oxygenated hemoglobin during RST. Verification data were from 62 children with ADHD and 37 TD children from six facilities in Japan. Results: The SVM general performance results showed sensitivity of 88.71%, specificity of 83.78%, and an overall discrimination rate of 86.25%. Conclusion: A SVM using an objective index from RST may be useful as an auxiliary biomarker for diagnosis for children with ADHD.

Atypical gamma functional connectivity pattern during light sleep in children with attention deficit hyperactivity disorder.

INTRODUCTION: We examined functional connectivity analyses in electroencephalograms (EEGs) of patients with attention deficit hyperactivitydisorder (ADHD) and in those of typically developing children (TDC) to uncover neurobiological abnormalities. METHODOLOGY: We enrolled 31 children with ADHD (mean age 11.1 years; 23 boys) and 17 sex-, age-, and intelligence-matched TDC to undergo 19-channel EEGs during light sleep. We estimated functional connectivity using the phase lag index (PLI) and coherence measurements that capture the synchronization of EEG signals and graphed metrics with GRETNA. We also performed continuous performance tests (CPTs) on the children and obtained answered questionnaires on ADHD and autism spectrum disorder. RESULTS: The central-to-posterior gamma PLI was lower in children with ADHD than that in TDC. The other PLI frequency bands and all coherence frequency bands were not statistically different between both groups. Individuals with high hyperactivity scores on questionnaires and low reaction times (SDs) on CPT had low motor and occipital pairs of gamma PLIs. Graph metrics showed no differences between the groups. CONCLUSIONS: The difference in averaged gamma PLI (especially with motor and occipital pairs) between groups was more suitable for diagnosis than the averaged coherence. Lower averaged gamma PLIs reflected more severe ADHD symptoms. A prospective study with more controlled conditions is warranted to determine if gamma-band PLI can be used as an auxiliary tool for ADHD diagnosis.

Prevalence estimates of neurodevelopmental disorders in Japan: A community sample questionnaire study.

AIM: Prevalence estimates of neurodevelopmental disorders have been calculated by questionnaire surveys scored by a single rater, which introduces inherent rater biases. The present study aimed to estimate the prevalence and comorbidity rates of four neurodevelopmental disorders based on both parent and teacher rating scales. METHODS: We performed a community sample survey recruiting 3852 children aged 6 to 9 years. Parents and teachers evaluated clinical conditions in children using questionnaire-style scales. These scales with cut-off values were used to estimate the prevalence and comorbidity rates of attention deficit hyperactive disorder, autism spectrum disorder, specific learning disorder (or developmental dyslexia), and developmental coordination disorder. RESULTS: The prevalence estimates were separately confirmed according to the raters. Some estimates were higher than those in previous studies conducted in other countries. We also found a large disagreement between the parent and teacher rating scores. Moreover, the degree of agreement between two raters varied depending on the severity of the child's clinical condition. CONCLUSION: These estimates are the first findings based on evaluating children by two different raters. The prevalence and comorbidity estimates are informative for researchers and clinicians of pediatric neurology. The disagreements between two different raters raise questions about previous estimates of neurodevelopmental disorders.

Alteration of the anatomical covariance network after corpus callosotomy in pediatric intractable epilepsy.

PURPOSE: This study aimed to use graph theoretical analysis of anatomical covariance derived from structural MRI to reveal how the gray matter connectivity pattern is altered after corpus callosotomy (CC). MATERIALS AND METHODS: We recruited 21 patients with epilepsy who had undergone CC. Enrollment criteria were applied: (1) no lesion identified on brain MRI; (2) no history of other brain surgery; and (3) age not younger than 3 years and not older than 18 years at preoperative MRI evaluation. The most common epilepsy syndrome was Lennox-Gastaut syndrome (11 patients). For voxel-based morphometry, the normalized gray matter images of pre-CC and post-CC patients were analyzed with SPM12 (voxel-level threshold of p<0.05 [familywise error-corrected]). Secondly, the images of both groups were subjected to graph theoretical analysis using the Graph Analysis Toolbox with SPM8. Each group was also compared with 32 age- and sex-matched control patients without brain diseases. RESULTS: Comparisons between the pre- and post-CC groups revealed a significant reduction in seizure frequency with no change in mean intelligence quotient/developmental quotient levels. There was no relationship among the three groups in global network metrics or in targeted attack. A regional comparison of betweenness centrality revealed decreased connectivity to and from the right middle cingulate gyri and medial side of the right superior frontal gyrus and a partial shift in the distribution of betweenness centrality hubs to the normal location. Significantly lower resilience to random failure was found after versus before CC and versus controls (p = 0.0450 and p = 0.0200, respectively). CONCLUSION: Graph theoretical analysis of anatomical covariance derived from structural imaging revealed two neural network effects of resection associated with seizure reduction: the reappearance of a structural network comparable to that in healthy children and reduced connectivity along the median line, including the middle cingulate gyrus.

Association of inattention with slow-spindle density in sleep EEG of children with attention deficit-hyperactivity disorder.

OBJECTIVE: We evaluated the power of slow sleep spindles during sleep stage 2 to clarify their relationship with executive function, especially with attention, in children with attention deficit-hyperactivity disorder (ADHD). METHODS: Subjects were 21 children with ADHD and 18 aged-matched, typically developing children (TDC). ADHD subjects were divided into groups of only ADHD and ADHD + autism spectrum disorder (ASD). We employed the Continuous Performance Test (CPT) to measure attention. We focused on sleep spindle frequencies (12-14 Hz) in sleep stage 2 and performed a power spectral analysis using fast Fourier transform techniques and compared sleep spindles with the variability of reaction time in CPT. RESULTS: In the CPT, reaction variabilities in ADHD and ADHD + ASD significantly differed from those in TDC. Twelve-hertz spindles were mainly distributed in the frontal pole and frontal area and 14-Hz spindles in the central area. The ratio of 12-Hz frontal spindle power was higher in ADHD than in TDC, especially in ADHD + ASD. Significant correlation between the ratio of 12-Hz spindles and reaction time variability was observed. CONCLUSIONS: Twelve-hertz frontal spindle EEG activity may have positive associations with sustained attention function. Slow frontal spindles may be useful as a biomarker of inattention in children with ADHD.

Age-related differences in frontal lobe function in children with ADHD.

BACKGROUND: The neural correlates of executive function disorders are thought to be predominantly localized within the prefrontal cortex (PFC). However, no study to date has investigated changes in this system across different age groups in children with attention deficit hyperactivity disorder (ADHD). Thus, this study aimed to explore changes in PFC function in children with ADHD. METHODS: Study participants included typically developing (TD) children (n = 140) and children with ADHD (n = 67) of primary school age. Behavioral executive functions and their neural basis were evaluated between the TD children and children with ADHD and also across different age periods (younger and older children). To examine executive function, inhibitory control was assessed using the reverse Stroop task, and PFC near-infrared spectroscopic measurements were used to investigate the neural mechanisms involved. RESULTS: Both ADHD symptoms and the ability to inhibit color interference improved with age. Compared to TD children, children with ADHD demonstrated decreased activation of the right and middle PFC across all age groups. Interestingly, the left PFC appeared to play a compensatory role. CONCLUSION: Children with ADHD exhibited changes in PFC function that varied with age. Longitudinal studies are required to assess the potential of using PFC function as an early biomarker of ADHD.

Is the motor skills checklist appropriate for assessing children in Japan?

PURPOSE: Motor skill screening tools are essential for the early detection of developmental coordination disorder (DCD). The present study aimed to examine any cultural and rater effects on these tools. This then enabled us to judge the validity of the original cut-off values for identifying diagnosable children. METHODS: A community sample survey was performed in Japan; 3852 children aged 6-9 years were recruited. Both parents and teachers evaluated the motor skills of their children using the Movement Assessment Battery for Children - Second Edition Checklist. The psychometric properties were evaluated and the scoring characteristics examined based on the type of rater and country of origin, as compared to data originally sampled in the UK. RESULTS: High reliability and validity of the Japanese samples were confirmed. The Japanese adults evaluated their children's motor skills more rigorously than the Europeans. Additionally, there was a large disagreement between parent and teacher rating scores; the degree of agreement varied depending on the severity of motor deficits in the child. CONCLUSION: The first findings from a Japanese sample suggest that the assessment of motor skills in children is significantly affected by culture and rater. These cultural characteristics and rater biases strongly suggest that new cut-off values, reflecting country and rater type, be introduced for identifying children at risk of DCD.