Electroencephalography Signatures Associated with Developmental Dyslexia Identified Using Principal Component Analysis

Developmental dyslexia (DD) and attention-deficit/hyperactivity disorder (ADHD) are two of the most common neurodevelopmental disorders among school-age children. These disorders frequently co-occur, with up to 40–50% of children with one diagnosis meeting criteria for the other, and similar percentages of children with either DD or ADHD exhibiting impaired executive functions (EF). Although both ADHD and EF deficits are common in dyslexia, there is little evidence about how ADHD and EF deficits specifically influence the brain basis of reading difficulty in dyslexia, and whether the influences of ADHD and EF on dyslexia can be disentangled. The goal of the current study was to investigate, at both behavioral and brain levels, whether reading performance in individuals with dyslexia is more strongly associated with EF or with diagnostic status of comorbid ADHD. We examined reading abilities and EF in children (8-13 years old) with typical reading ability, DD only, or both DD + ADHD. Across both groups with dyslexia, impaired EF was associated with greater impairment on measures loading onto a reading fluency, but not a reading accuracy, factor. There were no significant differences between the DD and DD + ADHD groups on measures of reading fluency or reading accuracy. During functional magnetic resonance imaging (fMRI) while performing a rhyme-matching reading task requiring phonological awareness, typically developing readers showed greater left-hemisphere reading network activation than children with DD or DD + ADHD. Children with DD and DD + ADHD did not show differential activation, but DD children with unimpaired EF showed greater activation than those with impaired EF in reading-related areas. Thus, ADHD status alone had no measurable influence on reading performance or brain activation. Impaired EF in dyslexia, independent of ADHD status, was associated with greater deficits in reading fluency and greater reductions of activation in response to print in the typical left-hemisphere reading network.

Association Between Knee Joint Muscle Activation and Knee Joint Moment Patterns During Walking in Moderate Medial Compartment Knee Osteoarthritis: Implications for Secondary Prevention

Developmental dyslexia (DD) is a common reading disorder with neurological underpinnings; however, it remains unclear whether Chinese children with DD exhibit spectral power or network topology abnormalities. This study investigated spectral power and brain network topology abnormalities using electroencephalography (EEG) during resting states and a one-back Chinese-Korean character task in 85 Hong Kong Chinese children with DD and 51 typically developing peers (ages 7–11). EEG signals were transformed using the Fast Fourier Transform to estimate spectral power. Functional connectivity matrices were derived using the phase-lag index, and network topology was assessed via minimum spanning tree (MST) analysis. The results suggested that children with DD showed reduced alpha power over central, frontal, temporal, parietal, and occipital scalp areas at rest, and over central and frontal areas during the task. MST results revealed decreased beta band integration at rest but increased alpha band integration during the one-back task. Familiar Chinese stimuli elicited greater alpha and beta power and lower beta band integration compared to unfamiliar Korean stimuli. Moreover, resting-state beta band integration correlated positively with reading fluency in children with DD. These findings point to inhibitory control deficits and cortical hyperactivation in Chinese DD, reflected in disrupted large-scale network topology, and highlight the alpha band as a potential biomarker. They also demonstrate that language familiarity modulates neural efficiency and recruits compensatory networks. Overall, the study provides new insights into the neural basis of reading difficulties in Chinese children with DD.

Trauma-induced coagulopathy is common and associated with poor outcomes in injured children. Our aim was to identify patterns of coagulopathy after injury using endothelial, platelet, and coagulation biomarkers, and associate these phenotypes with relevant patient factors and clinical outcomes in a pediatric trauma cohort. Principal component (PC) analysis was performed on data from injured children between 2018 and 2022. Laboratories included endothelial markers (syndecan-1, thrombomodulin, tissue factor, and vascular endothelial growth factor), international normalized ratio, platelet count, rapid thromboelastography maximum amplitude, and base deficit. Variables were reduced to PCs; PC scores were generated for each subject and used in logistic regression with outcomes including mortality, blood transfusion, shock (pediatric-adjusted shock index), and patient characteristics including age, sex, injury mechanism, and traumatic brain injury. In total, 59 children had complete data for analysis. Median (interquartile range) age was 10 (4-14) years, 31% female, 21% penetrating mechanism, and median (interquartile range) injury severity score of 16 (9-21). Principal component analysis identified two significant PCs accounting for 67% of overall variance. PC1 included syndecan-1, thrombomodulin, vascular endothelial growth factor, international normalized ratio, and base deficit; PC1 scores were associated with mortality, blood transfusion, and shock (all p < 0.001). PC2 included tissue factor, platelet count, and rapid thromboelastography maximum amplitude; PC2 scores were associated with age (ρ = -0.42, p = 0.001) but no studied clinical outcome. Neither PC was significantly associated with sex, injury mechanism, or traumatic brain injury. Principal component analysis detected two distinct biomarker patterns in injured children involving the domains of the endothelium, coagulation, and platelets. The first phenotype was associated with poor clinical outcomes, while the second was associated with age. This supports the concept that pediatric trauma-induced coagulopathy elicits a heterogeneous response, and suggests that there may be a prognostic value to these phenotypes that warrants further investigation. Prognostic and Epidemiological; Level IV.

In order to investigate the strength reduction of particleboards subjected to outdoor exposure at eight sites across Japan, the climate factors, i.e., temperature, sunshine duration, and precipitation were analyzed using a principal component analysis. The first principal component (PC1) had an eigenvalue of 2.31 and a proportion of 76.9 %, indicating that the PC1 combines the climate factors into one factor. All of the PC1 eigenvectors demonstrated high, positive values for each climate factor, demonstrating that the first principal component score (PC1 score) increases with increasing temperature, sunshine duration, and precipitation. The PC1 score was introduced as a new index for evaluating strength reduction, as the strength shows a strong correlation with the PC1 score: a higher PC1 score was linked to lower particleboard strength after the outdoor exposure test. The PC1 score can be calculated directly and unambiguously using the climate factors; further, the PC1 score was found to be a more powerful index than each individual climate factors or a combination of them.

Electroencephalographic examination of boys aged 4–9 years with autism spectrum disorders (ASDs) showed spectral power values and coherence in high-frequency bands (20–60 Hz) in various brain areas were higher than normal. Differences in spectral power were greater in the anterior areas of the left hemisphere; differences in coherence, in the right anterior and posterior areas. Interhemispheric differences typical of healthy subjects were absent in the children with ASDs. The spectral power of the θ rhythm was lower in autism, especially in the left hemisphere. The spectral power of the α rhythm in the autistic children was lower than normal, especially in the posterior areas of the left hemisphere. The μ rhythm was higher than normal in spectral power and was localized in the right, rather than left, anterior areas. The children were examined again after corrective procedures. The α-rhythm spectral power increased (became closer to the norm) in the left posterior areas, while the γ-rhythm spectral power decreased (became closer to the norm) in the right anterior areas in some of the autistic children. The electrophysiological changes were associated with improved psychological testing results, especially in nonverbal measures.

Exposure to endocrine-disrupting chemicals including PBDEs during the prenatal period may affect breast development and composition and the risk of developing breast cancer in adulthood. We examined the association between prenatal exposure to PBDEs and breast tissue composition in adolescent girls. We used data from the Columbia’s Breast Cancer and the Environment Research Project (BCERP), part of the Columbia Center for Children's Environmental Health birth cohort. Prenatal PBDE concentrations were measured in cord blood from African-American or Dominican neonates, born between 1998 and 2006 (prior to PBDE phase out). After longitudinal follow-up, breast tissue composition was measured using optical spectroscopy (OS) in adolescent girls between 2016 and 2020. OS is a non-invasive device that uses visible and near infrared light to provide a broad compositional view of the breast by capturing variation in the amount of water, lipid, oxy-hemoglobin, deoxy-hemoglobin (HbO2), and collagen, and cellular and connective tissue density. Spectral data was reduced using principal component analysis and principal component (PC) scores were generated for each girl (averaged over both breasts). Associations between lipid-adjusted PBDE concentrations (ln) and PC scores were evaluated using linear regression. The analysis included 94 daughters (ages 12.6 to 19.9 years, median=16.9 years). Five PCs explained 99.9% of the variation in OS data. When examining PBDE as continuous, PC2 scores were lower on average for girls with higher prenatal concentrations of BDE-47 (overall sample geometric mean = 11.82 ng/g lipid; βBDE-47 = -0.05, 95% CI:-0.09, -0.005) after adjusting for age and body mass index. Results were consistent when examining PBDEs using median cut-points. PC2 covered 3.8% of the spectral variations and was related to overall lower HbO2 and higher water. Associations were attenuated in fully adjusted models. We found evidence suggesting that prenatal exposure to PBDEs may be associated with breast tissue composition in adolescent girls.

ObjectiveAlternating Hemiplegia of Childhood (AHC) is characterised by paroxysmal hemiplegic episodes and seizures. Remission of hemiplegia upon sleep is a clinical diagnostic feature of AHC. We investigated whether: 1) Hemiplegic events are associated with spectral EEG changes 2) Sleep in AHC is associated with clinical or EEG spectral features that may explain its restorative effect.MethodsWe retrospectively performed EEG spectral analysis in five adults with AHC and twelve age-/gender-matched epilepsy controls. Five-minute epochs of hemiplegic episodes and ten-minute epochs of four sleep stages were selected from video-EEGs. Arousals were counted per hour of sleep.ResultsWe found 1) hemispheric differences in pre-ictal and ictal spectral power (p = 0.034), during AHC hemiplegic episodes 2) 22% reduced beta power (p = 0.017) and 26% increased delta power (p = 0.025) during wakefulness in AHC versus controls. There were 98% more arousals in the AHC group versus controls (p = 0.0003).ConclusionsThere are hemispheric differences in spectral power preceding hemiplegic episodes in adults with AHC, and sleep is disrupted.SignificanceSpectral EEG changes may be a potential predictive tool for AHC hemiplegic episodes. Significantly disrupted sleep is a feature of AHC.

Alternating Hemiplegia of Childhood (AHC) is characterised by paroxysmal hemiplegic episodes and seizures. Remission of hemiplegia upon sleep is a clinical diagnostic feature of AHC. We investigated whether: 1) Hemiplegic events are associated with spectral EEG changes 2) Sleep in AHC is associated with clinical or EEG spectral features that may explain its restorative effect. We retrospectively performed EEG spectral analysis in five adults with AHC and twelve age-/gender-matched epilepsy controls. Five-minute epochs of hemiplegic episodes and ten-minute epochs of four sleep stages were selected from video-EEGs. Arousals were counted per hour of sleep. We found 1) hemispheric differences in pre-ictal and ictal spectral power (p = 0.034), during AHC hemiplegic episodes 2) 22% reduced beta power (p = 0.017) and 26% increased delta power (p = 0.025) during wakefulness in AHC versus controls. There were 98% more arousals in the AHC group versus controls (p = 0.0003). There are hemispheric differences in spectral power preceding hemiplegic episodes in adults with AHC, and sleep is disrupted. Spectral EEG changes may be a potential predictive tool for AHC hemiplegic episodes. Significantly disrupted sleep is a feature of AHC.

Neuropsychological outcomes after pediatric epilepsy surgery: Role of electrical stimulation language mapping

Attention deficit-hyperactivity disorder (ADHD) and dyslexia are frequently co-occuring disorders. The objective of this study is to compare the neuropsychological profile of subjects with ADHD and Dyslexia in relation to the presence of the two disorders isolated on a sample of Italian language. The total sample (N = 39) was divided into three clinical groups: ADHD with Dyslexia (n=10), ADHD (n=11), Dyslexia (n=18) and a control group was recruited (n=20 ). The ADHD group presented more difficulties than the Dyslexia group in performance skills and in accuracy of attention abilities. In reading performance the Dyslexia group was slower than the ADHD group but faster than the comorbid group. There was no differences between the three clinical groups in the accuracy of reading. The results in the Conners' have found more problems of hyperactivity in the ADHD group compared to the comorbid group in the Conners' Teachers, and the Dyslexia group obtained a score higher than controls on several subscales of both the Conners' Parents and Teachers. In agreement with previous studies, the present study confirmed the importance of characterizing the neuropsychological profile of each condition to clarify the relationship between ADHD and Dyslexia. On clinical emphasizes the need of a diagnostic-functional approach to the ADHD and Dyslexia assessment not to exclude comorbidity.

The acquisition of letter-speech sound associations is one of the basic requirements for fluent reading acquisition and its failure may contribute to reading difficulties in developmental dyslexia. Here we investigated event-related potential (ERP) measures of letter-speech sound integration in 9-year-old typical and dyslexic readers and specifically test their relation to individual differences in reading fluency. We employed an audiovisual oddball paradigm in typical readers (n = 20), dysfluent (n = 18) and severely dysfluent (n = 18) dyslexic children. In one auditory and two audiovisual conditions the Dutch spoken vowels/a/and/o/were presented as standard and deviant stimuli. In audiovisual blocks, the letter ‘a’ was presented either simultaneously (AV0), or 200 ms before (AV200) vowel sound onset. Across the three children groups, vowel deviancy in auditory blocks elicited comparable mismatch negativity (MMN) and late negativity (LN) responses. In typical readers, both audiovisual conditions (AV0 and AV200) led to enhanced MMN and LN amplitudes. In both dyslexic groups, the audiovisual LN effects were mildly reduced. Most interestingly, individual differences in reading fluency were correlated with MMN latency in the AV0 condition. A further analysis revealed that this effect was driven by a short-lived MMN effect encompassing only the N1 window in severely dysfluent dyslexics versus a longer MMN effect encompassing both the N1 and P2 windows in the other two groups. Our results confirm and extend previous findings in dyslexic children by demonstrating a deficient pattern of letter-speech sound integration depending on the level of reading dysfluency. These findings underscore the importance of considering individual differences across the entire spectrum of reading skills in addition to group differences between typical and dyslexic readers.

Dyslexia can be defined as an unexpected difficulty in reading in individuals who otherwise possess the intelligence, motivation and schooling, thus factors considered to be vital and crucial for accurate and fluent reading. This specific learning disability is assumed to be neurobiological in origin and it is related to a variety of impairments in processing sensory information. Due to these neuropsychological deficits, it is proposed that Event Related Potentials (ERPs) is a scientific tool for the assessment of dyslexic children by providing data about the neuronal activity which is related to cognitive information processing. Despite of the delayed brain activity and latency values differences being observed in dyslexic children comparing to typical readers, scientific research data confirm that normalization can be achieved, as changes in brain activation may occur and children΄s reading ability could be improved, through the implementation of a structured intervention. Indeed, even brief periods of training can evoke changes in the brain's ERPs responses and, actually, with lasting benefits. The aim of this study was to investigate the effect of a remediation - training program being implemented to dyslexic children, on ERPs esp. P300 waveform latency values. ERPs were obtained from 15 electrode sites (Fp1, Fpz, Fp2, F3, Fz, F4, F7, F8, C3, Cz, C4, P3, Pz, P4, Oz) according to the 10 – 20 International System (Jasper, 1958), plus 2 reference electrodes at the mastoids of each ear and one ground electrode at the Nz (nose) site in six Greek right handed children with developmental dyslexia (mean age 9 years and 8 months). Impedances for all electrodes were kept below 5 kohms. Six control children matched on chronological age and IQ level were also tested.Results from the first assessment confirmed that dyslexic children differed significantly from control group, in presenting a longer P300 latency values and anomalous, thus right hemispheric, lateralization. After the initial assessment, children with dyslexia received intensive six-month training program included exercises for enhancing phonological skills (syllable counting, phoneme detection, phoneme blending, rhyme detection) visual and auditory memory (sounds and pictures matching, picture & word sequencing), visual perception and attention (coding, spotting the differences between five similar pictures). Data analysis displayed significant improvement for the dyslexic group after their participation to the remediation program, as they showed a significant decrease in P300 latency. Actually, children with dyslexia, after training, tend to have similar to controls P300 wave latency values and developed a brain activation profile more similar to that of the typically developing control group, showing, left hemispheric lateralization.

In NIR spectroscopy, multidimensional analyses such as Principal Component Analysis (PCA) may be applied to examine the similarity between spectra of natural products. However, such an approach is often limited by the effect of spectral interference due to water or particle size distribution of the samples. In the present work, the advantage of the elimination of such spectral interference before performing PCA was investigated. Unwanted component spectra were eliminated by a least-squares procedure. They were first orthogonalized and normalized by the Gram-Schmidt orthogonalization method. The subtraction coefficients were then assessed, similarly to principal component (PC) scores, by projection of the NIR spectra on the orthogonalized component spectra, and PCA was performed on the corrected spectra. This method was applied on an illustrative collection of wheat semolina conditioned in three levels of water content. Water was the component to be eliminated and had been previously modeled by two spectral patterns. These spectral patterns were used as the unwanted component spectra. PCA was applied independently before and after spectral correction of the collection of spectra and graphs obtained by the two procedures were compared. The squared correlation coefficient of the 3 first PC scores with water content was 0.979 before correction, with the 3 groups of water content appearing clearly on PCA graphs. After correction, the corresponding squared correlation coefficient for the 7 first PC scores was 0.016. PCA graphs obtained with corrected spectra also showed that the water effect was completely eliminated. At this moment, samples were separated according to their technological nature. The procedure developed may be useful in pattern recognition study and for automatic clustering of NIR spectra. It may also be applied in fields other than NIR spectroscopy.

Developmental Dyslexia (DD) is a condition in which reading accuracy and/or fluency falls substantially below what is expected based on the individuals age, general level of cognitive ability, and educational opportunities. The procedural circuit deficit hypothesis (PDH) proposes that DD may be largely explained in terms of alterations of the cortico‐basal ganglia procedural memory system (in particular of the striatum) whereas the (hippocampus‐dependent) declarative memory system is intact, and may serve a compensatory role in the condition. The present study was designed to test this hypothesis. Using Magnetic Resonance Imaging, we examined the functional and structural brain correlates of sequence‐specific procedural learning (SL) on the serial reaction time task, in 17 children with DD and 18 typically developing (TD) children. The study was performed over 2 days with a 24‐h interval between sessions. In line with the PDH, the DD group showed less activation of the striatum during the processing of sequential statistical regularities. These alterations predicted the amount of SL at day 2, which in turn explained variance in children's reading fluency. Additionally, reduced hippocampal activation predicted larger SL gains between day 1 and day 2 in the TD group, but not in the DD group. At the structural level, caudate nucleus volume predicted the amount of acquired SL at day 2 in the TD group, but not in the DD group. The findings encourage further research into factors that promote learning in children with DD, including through compensatory mechanisms.