Altered Functional Connectivity of the Executive Functions Network During a Stroop Task in Children with Reading Difficulties

Functional connectivity compensation in Parkinson's disease with freezing of gait

Freezing of gait (FOG) is a disabling motor symptom prevalent in patients with Parkinson's disease (PD); however, its pathophysiological mechanisms are poorly understood. This study aimed to investigate whole-brain functional connectivity (FC) pattern alterations in PD patients with FOG. A total of 18 PD patients, 10 with FOG (PD-FOG) and 8 without FOG (PD-nFOG), and 10 healthy controls were enrolled. High-resolution 3D T1-weighted and resting-state functional MRI (rs-fMRI) data were obtained from all participants. The groups' internetwork connectivity differences were explored with rs-fMRI FC using seed-based analysis and graph theory. Multiple linear regression analysis estimated the relationship between FC changes and clinical measurements. Rs-fMRI analysis demonstrated alterations in FC in various brain regions between the three groups. Freezing of Gait Questionnaire severity was correlated with decreased brain functional connection between Vermis12 and the left temporal occipital fusiform cortex (r = -0.82, P < .001). Graph theory topological metrics indicated a decreased clustering coefficient in the right superior temporal gyrus in the PD-nFOG group. PD-FOG patients exhibited a compensatory increase in connectivity between the left inferior frontal gyrus language network and the postcentral gyrus compared to PD-nFOG patients. Further, the decreased connection between Vermis 12 and the left temporal occipital fusiform cortex may serve as a potential neuroimaging biomarker for tracking PD-FOG and distinguishing between PD subtypes.

Greater utilization of executive functions networks when listening to stories with visual stimulation is related to lower reading abilities in children

Narrative comprehension relies on basic sensory processing abilities, such as visual and auditory processing, with recent evidence for utilizing executive functions (EF), which are also engaged during reading. EF was previously related to the "supporter" of engaging the auditory and visual modalities in different cognitive tasks, with evidence of lower efficiency in this process among those with reading difficulties in the absence of a visual stimulus (i.e. while listening to stories). The current study aims to fill out the gap related to the level of reliance on these neural circuits while visual aids (pictures) are involved during story listening in relation to reading skills. Functional MRI data were collected from 44 Hebrew-speaking children aged 8-12 years while listening to stories with vs without visual stimuli (i.e., pictures). Functional connectivity of networks supporting reading was defined in each condition and compared between the conditions against behavioral reading measures. Lower reading skills were related to greater functional connectivity values between EF networks (default mode and memory networks), and between the auditory and memory networks for the stories with vs without the visual stimulation. A greater difference in functional connectivity between the conditions was related to lower reading scores. We conclude that lower reading skills in children may be related to a need for greater scaffolding, i.e., visual stimulation such as pictures describing the narratives when listening to stories, which may guide future intervention approaches.

An executive-functions-based reading training enhances sensory-motor systems integration during reading fluency in children with dyslexia

The Simple View of Reading model suggests that intact language processing and word decoding lead to proficient reading comprehension, with recent studies pointing at executive functions as an important component contributing to reading proficiency. Here, we aimed to determine the underlying mechanism(s) for these changes. Participants include 120 8- to 12-year-old children (n = 55 with dyslexia, n = 65 typical readers) trained on an executive functions-based reading program, including pre/postfunctional MRI and behavioral data collection. Across groups, improved word reading was related to stronger functional connections within executive functions and sensory networks. In children with dyslexia, faster and more accurate word reading was related to stronger functional connections within and between sensory networks. These results suggest greater synchronization of brain systems after the intervention, consistent with the "neural noise" hypothesis in children with dyslexia and support the consideration of including executive functions as part of the Simple View of Reading model.

Neural Changes in Children With Residual Speech Sound Disorder After Ultrasound Biofeedback Speech Therapy

PURPOSE

Children with residual speech sound disorders (RSSD) have shown differences in neural function for speech production, as compared to their typical peers; however, information about how these differences may change over time and relative to speech therapy is needed. To address this gap, we used functional magnetic resonance imaging (fMRI) to examine functional activation and connectivity on adaptations of the syllable repetition task (SRT-Early Sounds and SRT-Late Sounds) in children with RSSD before and after a speech therapy program.

METHOD

Sixteen children with RSSD completed an fMRI experiment before (Time 1) and after (Time 2) a speech therapy program with ultrasound visual feedback for /ɹ/ misarticulation. Progress in therapy was measured via perceptual ratings of productions of untreated /ɹ/ word probes. To control for practice effects and developmental change in patterns of activation and connectivity, 17 children with typical speech development (TD) completed the fMRI at Time 1 and Time 2. Functional activation was analyzed using a region-of-interest approach and functional connectivity was analyzed using a seed-to-voxel approach.

RESULTS

Children with RSSD showed a range of responses to therapy. After correcting for multiple comparisons, we did not observe any statistically significant cross-sectional differences or longitudinal changes in functional activation. A negative relationship between therapy effect size and functional activation in the left visual association cortex was on the SRT-Late Sounds after therapy, but it did not survive correction for multiple comparisons. Significant longitudinal changes in functional connectivity were observed for the RSSD group on SRT-Early Sounds and SRT-Late Sounds, as well as for the TD group on the SRT-Early Sounds. RSSD and TD groups showed connectivity differences near the left insula on the SRT-Late Sounds at Time 2.

CONCLUSION

RSSD and treatment with ultrasound visual feedback may thus be associated with neural differences in speech motor and visual association processes recruited for speech production.

Pathogenesis of Comorbid ADHD and Chinese Developmental Dyslexia: Evidence From Eye-Movement Tracking and Rapid Automatized Naming

BACKGROUND

ADHD and Chinese developmental dyslexia (DD) have a very high comorbidity rate; however, which cognitive deficits characterize the comorbidity and when they occur during cognitive processing are still under debate.

METHODS

Rapid automatic naming (RAN) tasks with eye-movement tracking were conducted with 75 children who were typically developing, had comorbid ADHD and DD, had only ADHD, and had only DD.

RESULTS

The clinical groups had longer first fixation durations than the control for RAN digits. Temporal eye-movement measures, such as gaze duration and total reading time, were found to vary between the comorbidity and ADHD groups. Spatial eye-movement measures, such as regression probability and incoming saccade amplitude, differed between the comorbidity and DD groups.

CONCLUSIONS

These results indicate that investigation with eye-movement measures combined with RAN tasks can strengthen the understanding of the pathogenesis of comorbid ADHD and DD.

Structural white matter characteristics for working memory and switching/inhibition in children with reading difficulties: The role of the left superior longitudinal fasciculus

Reading difficulties (RDs) are characterized by slow and inaccurate reading as well as additional challenges in cognitive control (i.e., executive functions, especially in working memory, inhibition, and visual attention). Despite evidence demonstrating differences in these readers' language and visual processing abilities, white matter differences associated with executive functions (EFs) difficulties in children with RDs are scarce. Structural correlates for reading and EFs in 8- to 12-year-old children with RDs versus typical readers (TRs) were examined using diffusion tensor imaging (DTI) data. Results suggest that children with RDs showed significantly lower reading and EF abilities versus TRs. Lower fractional anisotropy (FA) in left temporo-parietal tracts was found in children with RDs, who also showed positive correlations between reading and working memory and switching/inhibition scores and FA in the left superior longitudinal fasciculus (SLF). FA in the left SLF predicted working memory performance mediated by reading ability in children with RDs but not TRs. Our findings support alterations in white matter tracts related to working memory, switching/inhibition, and overall EF challenges in children with RDs and the linkage between working memory difficulties and FA alterations in the left SLF in children with RDs via reading.

Stroop performance is related to reading profiles in Hebrew-speaking individuals with dyslexia and typical readers

There is a debate in the literature regarding the level of contribution of executive functions (EF) to reading comprehension (RC), in the context of the simple view of reading (SVR) model. The current study aims to create sub-profiles of reading and cognitive abilities based on a measure traditionally used for evaluating EF, that is, the Stroop task, and specifically, Stroop time. Ninety-seven adults with and without reading difficulties performed reading and cognitive tasks, including the Stroop tests. Four groups were created based on Stroop performance time and a reading profile was created for each group. A mediation analysis was conducted to determine if reading accuracy and linguistic abilities predict RC mediated by Stroop time. Participants with a shorter Stroop time demonstrated better reading abilities, whereas those with longer Stroop time showed decreased reading performance. Stroop time was also negatively associated with better performance in additional cognitive abilities. A mediation analysis suggested that decoding ability and linguistic ability predict RC through EF. Our findings support the SVR model and the involvement of EF in reading proficiency and might be used for designing EF-based interventions for reading and RC difficulties.

Longer Screen Vs. Reading Time is Related to Greater Functional Connections Between the Salience Network and Executive Functions Regions in Children with Reading Difficulties Vs. Typical Readers

An adverse relationship between screen exposure time and brain functional/structural connectivity was reported in typically developing children, specifically related to neurobiological correlates of reading ability. As children with reading difficulties (RD) suffer from impairments in reading and executive functions (EF), we sought to determine the association between the ratio of screen time duration to reading time duration and functional connectivity of EF networks to the entire brain in children with RD compared to typical readers (TRs) using resting state data. Screen/reading time ratio was related to reduced reading and EF abilities. A larger screen/reading time ratio was correlated with increased functional connectivity between the salience network and frontal-EF regions in children with RD compared to TRs. We suggest that whereas greater screen/reading time ratio is related to excessive stimulation of the visual processing system in TRs, it may be related to decreased efficiency of the cognitive control system in RDs.

Stroop interference in children with developmental dyslexia: An event-related potentials study

Previous studies have identified inhibitory deficits in dyslexic children, but we have little understanding of their neural mechanisms, especially for Chinese children with developmental dyslexia.We used a double-blind controlled trial to study the electroencephalogram responses of dyslexic and non-dyslexic children when performing the Stroop color-word test.Behavioral data showed differences in response time and accuracy between the 2 groups. In the event-related potentials (ERP) results, dyslexic children displayed larger P2 and P3b on congruent trials, while non-dyslexic children displayed larger P2 and P3b on incongruent trials, the 2 groups showed opposite brain activation patterns on the Stroop test.Dyslexic children have poor inhibitory function, and this poor inhibition may be related to their abnormal brain activation patterns.

Greater reading gain following intervention is associated with low magnetic resonance spectroscopy derived concentrations in the anterior cingulate cortex in children with dyslexia

BACKGROUND/OBJECTIVE

The "neural noise" hypothesis suggests that individuals with dyslexia have high glutamate concentrations associated with their reading challenges. Different reading intervention programs have showed low GLX (a combined measure for glutamine and glutamate obtained with in vivo magnetic resonance spectroscopy) in association with reading improvement. Several studies demonstrated improved reading and increased activation in the anterior cingulate cortex following an-executive-function (EF)-based reading intervention. The goals of the current study are two-fold: 1) to determine if the effect of the EF-based reading program extends also to the metabolite concentrations and in particular, on the GLX concentrations in the anterior cingulate cortex; 2) to expand the neural noise hypothesis in dyslexia also to neural networks supporting additional parts of the reading networks, i.e. in specific regions related to executive function skills.

METHODS

Children with dyslexia and typical readers were trained on the EF-based reading program. Reading ability was assessed before and after training while spectroscopy data was obtained at the end of the program. The association between change in reading scores following intervention and GLX concentrations was examined.

RESULTS

Greater "gains" in word reading were associated with low GLX, Glu, Cr, and NAA concentrations for children with dyslexia compared to typical readers.

CONCLUSIONS

These results suggest that the improvement reported following the EF-based reading intervention program also involved a low GLX concentration, as well as additional metabolites previously associated with better reading ability (Glx, Cr, NAA) which may point at the decreased neural noise, especially in the anterior cingulate cortex, as a possible mechanism for the effect of this program.

Bayesian Joint Modeling of Multiple Brain Functional Networks

Investigating the similarity and changes in brain networks under different mental conditions has become increasingly important in neuroscience research. A standard separate estimation strategy fails to pool information across networks and hence has reduced estimation accuracy and power to detect between-network differences. Motivated by a fMRI Stroop task experiment that involves multiple related tasks, we develop an integrative Bayesian approach for jointly modeling multiple brain networks that provides a systematic inferential framework for network comparisons. The proposed approach explicitly models shared and differential patterns via flexible Dirichlet process-based priors on edge probabilities. Conditional on edges, the connection strengths are modeled via Bayesian spike and slab prior on the precision matrix off-diagonals. Numerical simulations illustrate that the proposed approach has increased power to detect true differential edges while providing adequate control on false positives and achieves greater network estimation accuracy compared to existing methods. The Stroop task data analysis reveals greater connectivity differences between task and fixation that are concentrated in brain regions previously identified as differentially activated in Stroop task, and more nuanced connectivity differences between exertion and relaxed task. In contrast, penalized modeling approaches involving computationally burdensome permutation tests reveal negligible network differences between conditions that seem biologically implausible.

Decreased Functional Connectivity Between the Left Amygdala and Frontal Regions Interferes With Reading, Emotional, and Executive Functions in Children With Reading Difficulties

INTRODUCTION

Dyslexia is a reading disorder characterized by significant difficulty in reading, as well as reports of altered executive functions (EF). Children with reading difficulties (RD) experience a broad range of social and emotional problems. Recently it was suggested that children with RD have altered functional connections within the amygdala, which is related to emotional processing. Altered brain laterality related to reading was previously reported in children with RD. Hence, we sought to determine the differences in functional connectivity between the right and left emotional network as related to emotional challenges and the other reported difficulties in reading and EF in children with RD compared to typical readers.

METHODS

Sixty-four 8 to 12 year old children, 27 children with RD and 37 age-matched typical readers, participated in the study. Reading, emotional, and EF abilities were assessed. Global efficiency of the emotional network was calculated and compared between the groups, and left vs. right functional connectivity of the amygdala was tested using the CONN toolbox. Functional connectivity measures were then associated with measures of reading, emotional, and EF abilities.

RESULTS

Children with RD showed significantly decreased emotional and EF abilities compared to typical readers. A negative correlation between reading, emotional, and EF abilities was determined in both groups. Neuroimaging results showed decreased global efficiency measures within the emotional network in children with RD, who also showed lower functional connectivity between the amygdala and the left and right frontal pole regions. Results also indicated increased functional connectivity of the right vs. left amygdala with left and right pre-central and post-central gyri regions, which were related to decreased reading, emotional, and EF abilities in both typical readers and children with RD.

CONCLUSION

The positive relationship between EF and emotional abilities in children with RD strengthens the relationship between EF difficulties and emotional stress, which in turn may lower EF abilities (monitoring, inhibition, and attention) as well as decreased reading abilities. The emotional challenges in children with RD were associated with decreased functional connectivity of the left amygdala with pre/post central gyrus and cognitive-control regions. These findings suggest that although the right hemisphere is thought to be related to emotional stress, it was the decreased control of the left hemisphere that was related to emotional disturbance in children with RD.

Greater functional connectivity within the cingulo-opercular and ventral attention networks is related to better fluent reading: A resting-state functional connectivity study

Executive functions are higher-order cognitive abilities that affect many of our daily actions, including reading. A two-system model for cognitive control comprises a bottom-up system composed of the dorsal and ventral attention networks and a more evolved top-down system involving the frontoparietal and cingulo-opercular networks. We examined both within- and between-network functional connectivity of these four networks in 26 8-12-year-old children with readong difficulties and 30 age-matched typical readers using resting-state functional MRI. Fluency and nonfluency behavioral reading measures were collected, and the scores were analyzed together with the functional data. Children with reading difficulties did not differ in functional connectivity for the four networks compared to typical readers. Grouping the entire cohort into low vs. high fluency-level reading groups, however, revealed significantly higher functional connectivity values within the cingulo-opercular and ventral attention cognitive-control networks for the high fluency group. Higher functional connectivity Trends between the cognitive-control networks were also observed in the high fluency group compared to the low fluency group. A similar analysis using a nonfluency word-reading task grouping did not uncover differences between the two groups. The results emphasize the complexity of the fluency task, as a test that relies on cognitive-control abilities, at both the bottom-up and top-down levels. Therefore, it may be posited that the fluency task may also be a challenge for typical readers despite their intact performance. The results reinforce the relationship between fluent reading and functional connectivity of the cognitive-control networks, emphasizing the various cognitive-control abilities that underlie this complex reading ability.

Children With Dyslexia and Typical Readers: Sex-Based Choline Differences Revealed Using Proton Magnetic Resonance Spectroscopy Acquired Within Anterior Cingulate Cortex

Children with dyslexia exhibit slow and inaccurate reading, as well as problems in executive functions. Decreased signal activation in brain regions related to visual processing and executive functions has been observed with functional magnetic resonance imaging with reports of sex differences in brain patterns for visual processing regions. However, the underlying neurochemistry associated with deficits in executive functions for children with dyslexia has not been thoroughly evaluated. Reading ability and executive functions were assessed in fifty-three children [ages 8-12 years old, dyslexia (n = 24), and typical readers (n = 30)]. We employed short echo, single voxel, proton magnetic resonance spectroscopy to evaluate the perigenual anterior cingulate cortex (ACC). Pearson correlations were calculated between metabolite concentrations and measures of reading, processing speed, and executive function. Logistic regression models were used to determine the effects of brain metabolite concentrations, processing speed, and reading scores on dyslexia status. Differences by child's sex were also examined. Compared to typical readers, higher global executive composite t-score is associated with greater odds for dyslexia (OR 1.14; 95% CI 1.05, 1.23); increased processing speed appears to be protective for dyslexia (OR 0.95; 95% 0.89-1.00). After adjustment for multiple comparisons, females with dyslexia showed strong and significant negative correlations between processing speed and myo-inositol (r = -0.55, p = 0.005) and choline (r = -0.54, p = 0.005) concentrations; effect modification by sex was confirmed in linear regression models (psex∗Cho = 0.0006) and (psex∗mI = 0.01). These associations were not observed for males or the group as a whole. These findings suggest that children with dyslexia share difficulty in one or more areas of executive function, specifically those related to response time. Also, metabolite changes in the ACC may be present in children with dyslexia, especially for females, and may hold value as possible markers for dyslexia.