Reduced interhemispheric coherence in dyslexic adults

Dhar, Monica; Been, P.; Minderaa, Ruud B.; Althaus, Monika

doi:10.1016/j.cortex.2009.09.006

Cited by 36 publications

(19 citation statements)

References 25 publications

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“…One of those studies reported a significant correlation between a measure of global network efficiency and reading performance in typically reading children (Dimitriadis et al, 2013). Another study in adults found decreased and more diffused inter-hemisphere alpha coherence at centro-parietal sites in dyslexics relative to controls during a visuo-spatial attention task (Dhar et al, 2010). Our current findings, then, suggesting differences in the organization of alpha oscillatory activity in dyslexics further supports the relevance of these oscillations to cognitive and attentional mechanisms that may be important for optimal reading performance.…”

Section: Discussionmentioning

confidence: 98%

“…In relation to this, previous EEG/MEG connectivity studies have yielded a mixed pattern of results. Some studies reported higher coherence in dyslexics (Shiota et al, 2000; Arns et al, 2007); some observed reduced coherence in poor relative to typical readers (Nagarajan et al, 1999; Dhar et al, 2010); other studies found increased coherence in some EEG bands and reduced coherence in other bands (Marosi et al, 1995). On a methodological note, coherence estimates may be strongly affected by volume conduction and reference effects, while this seems to have less impact on PLI connectivity (Stam et al, 2007).…”

Section: Discussionmentioning

confidence: 99%

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EEG Resting State Functional Connectivity in Adult Dyslexics Using Phase Lag Index and Graph Analysis

González

Smit

Molen

et al. 2018

Front. Hum. Neurosci.

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Developmental dyslexia may involve deficits in functional connectivity across widespread brain networks that enable fluent reading. We investigated the large-scale organization of electroencephalography (EEG) functional networks at rest in 28 dyslexics and 36 typically reading adults. For each frequency band (delta, theta alpha and beta), we assessed functional connectivity strength with the phase lag index (PLI). Network topology was examined using minimum spanning tree (MST) graphs derived from the functional connectivity matrices. We found significant group differences in the alpha band (8–13 Hz). The graph analysis indicated more interconnected nodes, in dyslexics compared to typical readers. The graph metrics were significantly correlated with age in dyslexics but not in typical readers, which may indicate more heterogeneity in maturation of brain networks in dyslexics. The present findings support the involvement of alpha oscillations in higher cognition and the sensitivity of graph metrics to characterize functional networks in adult dyslexia. Finally, the current results extend our previous findings on children.

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Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

EEG Resting State Functional Connectivity in Adult Dyslexics Using Phase Lag Index and Graph Analysis

González

Smit

Molen

et al. 2018

Front. Hum. Neurosci.

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“…As QMT enhances spatial performance and may increase reflectivity, it would be worthwhile to examine it in the context of different learning and impulsivity-related disorders. Given that coherence alterations have long been observed in ADHD and dyslexia (Dhar et al, 2010; Barry et al, 2011), future studies should examine the effects of QMT in these populations. Critically, the advantage of QMT training lies in its simplicity of training, and minimal space needed compared to other movement contemplative practices, such as martial arts or walking meditation.…”

Section: Discussionmentioning

confidence: 99%

A suspended act: increased reflectivity and gender-dependent electrophysiological change following Quadrato Motor Training

et al. 2014

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Quadrato Motor Training (QMT) is a specifically-structured walking meditation, aimed at improving reflectivity and lowering habitual thought and movement. Here we set out to examine the possible effect of QMT on reflectivity, employing the Hidden Figures Test (HFT), which assesses both spatial performance (measured by correct answers) as well as reflectivity (interpolated from correct answers and reaction time). In the first study (n = 24, only females), we showed that QMT significantly improves HFT performance, compared to two groups, controlling for cognitive or motor aspects of the QMT: Verbal Training (identical cognitive training with verbal response) and Simple Motor Training (similar motor training with reduced choice requirements). These results show that QMT improves HFT performance above the pre-post expected learning. In the second study, building on previous literature showing gender-dependent effects on cognitive performance, we conducted a preliminary pilot examining gender-dependent effect of training on reflectivity and its electrophysiological counterparts. EEG analyses focused on theta, alpha and gamma coherence. HFT performance and resting-state EEG were measured in 37 participants (20 males), using a within-subject pre-post design. Following training, HFT performance improved in both genders. However, we found a gender-dependent difference in functional connectivity: while theta and alpha intra-hemispheric coherence was enhanced in females, the opposite pattern was found in males. These results are discussed in relation to neuronal efficiency theory. Together, the results demonstrate that QMT improves spatial performance, and may involve a gender-dependent electrophysiological effect. This study emphasizes both the importance of studying gender-related training effects within the contemplative neuroscience endeavor, as well as the need to widen its scope toward including “contemplation in action.”

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“…Compensatory networks have been identified in the IFG, and in right hemisphere regions homologous to the left posterior brain system (Ligges, Ungureanu, Ligges, Blanz, & Witte, 2010). Another characteristic that has been proposed is that individuals with RD have less efficient functional circuits (Casanova, El-Baz, Giedd, Rumsey, & Switala, 2010; Dhar, Been, Minderaa, & Althaus, 2010; Ligges et al, 2010; Vourkas et al, 2011). Preliminary evidence, however, suggests that abnormal connectivity in RD can normalize with appropriate intervention (Richards & Berninger, 2008), suggesting that these abnormalities may be state rather than trait markers.…”

Section: Neurobiology Of Rdmentioning

confidence: 99%

Neurobiological Underpinnings of Math and Reading Learning Disabilities

et al. 2013

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The primary goal of this review is to highlight current research and theories describing the neurobiological basis of math (MD), reading (RD), and comorbid math and reading disability (MD+RD). We first describe the unique brain and cognitive processes involved in acquisition of math and reading skills, emphasizing similarities and differences in each domain. Next we review functional imaging studies of MD and RD in children, integrating relevant theories from experimental psychology and cognitive neuroscience to characterize the functional neuroanatomy of cognitive dysfunction in MD and RD. We then review recent research on the anatomical correlates of MD and RD. Converging evidence from morphometry and tractography studies are presented to highlight distinct patterns of white matter pathways which are disrupted in MD and RD. Finally, we examine how the intersection of MD and RD provides a unique opportunity to clarify the unique and shared brain systems which adversely impact learning and skill acquisition in MD and RD, and point out important areas for future work on comorbid learning disabilities.

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Reduced interhemispheric coherence in dyslexic adults

Cited by 36 publications

References 25 publications

EEG Resting State Functional Connectivity in Adult Dyslexics Using Phase Lag Index and Graph Analysis

EEG Resting State Functional Connectivity in Adult Dyslexics Using Phase Lag Index and Graph Analysis

A suspended act: increased reflectivity and gender-dependent electrophysiological change following Quadrato Motor Training

Neurobiological Underpinnings of Math and Reading Learning Disabilities

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