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Fraga-González G, Smit DJA, Van der Molen MJW, Tijms J, Stam CJ, de Geus EJC, Van der Molen MW. Graph Analysis of EEG Functional Connectivity Networks During a Letter-Speech Sound Binding Task in Adult Dyslexics. Front Psychol 2021; 12:767839. [PMID: 34899515 PMCID: PMC8658451 DOI: 10.3389/fpsyg.2021.767839] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 10/26/2021] [Indexed: 11/16/2022] Open
Abstract
We performed an EEG graph analysis on data from 31 typical readers (22.27 ± 2.53 y/o) and 24 dyslexics (22.99 ± 2.29 y/o), recorded while they were engaged in an audiovisual task and during resting-state. The task simulates reading acquisition as participants learned new letter-sound mappings via feedback. EEG data was filtered for the delta (0.5–4 Hz), theta (4–8 Hz), alpha (8–13 Hz), and beta (13–30 Hz) bands. We computed the Phase Lag Index (PLI) to provide an estimate of the functional connectivity between all pairs of electrodes per band. Then, networks were constructed using a Minimum Spanning Tree (MST), a unique sub-graph connecting all nodes (electrodes) without loops, aimed at minimizing bias in between groups and conditions comparisons. Both groups showed a comparable accuracy increase during task blocks, indicating that they correctly learned the new associations. The EEG results revealed lower task-specific theta connectivity, and lower theta degree correlation over both rest and task recordings, indicating less network integration in dyslexics compared to typical readers. This pattern suggests a role of theta oscillations in dyslexia and may reflect differences in task engagement between the groups, although robust correlations between MST metrics and performance indices were lacking.
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Affiliation(s)
- Gorka Fraga-González
- Department of Psychology, University of Amsterdam, Amsterdam, Netherlands.,Rudolf Berlin Center, Amsterdam, Netherlands.,Department of Child and Adolescent Psychiatry and Psychotherapy, University Hospital of Psychiatry Zurich, University of Zurich, Zurich, Switzerland
| | - Dirk J A Smit
- Amsterdam Neuroscience, Amsterdam UMC, Amsterdam, Netherlands.,Neuroscience Campus Amsterdam, VU University, Amsterdam, Netherlands
| | - Melle J W Van der Molen
- Institute of Psychology, Leiden University, Leiden, Netherlands.,Leiden Institute for Brain and Cognition, Leiden University, Leiden, Netherlands
| | - Jurgen Tijms
- Department of Psychology, University of Amsterdam, Amsterdam, Netherlands.,Rudolf Berlin Center, Amsterdam, Netherlands.,RID Institute, Amsterdam, Netherlands
| | - Cornelis J Stam
- Department of Clinical Neuropsychology and MEG Center, VU University Medical Center, Amsterdam, Netherlands
| | - Eco J C de Geus
- Amsterdam Neuroscience, Amsterdam UMC, Amsterdam, Netherlands.,Neuroscience Campus Amsterdam, VU University, Amsterdam, Netherlands
| | - Maurits W Van der Molen
- Department of Psychology, University of Amsterdam, Amsterdam, Netherlands.,Amsterdam Brain and Cognition, University of Amsterdam, Amsterdam, Netherlands
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Jakovljević T, Janković MM, Savić AM, Soldatović I, Čolić G, Jakulin TJ, Papa G, Ković V. The Relation between Physiological Parameters and Colour Modifications in Text Background and Overlay during Reading in Children with and without Dyslexia. Brain Sci 2021; 11:539. [PMID: 33922926 PMCID: PMC8146078 DOI: 10.3390/brainsci11050539] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 04/18/2021] [Accepted: 04/20/2021] [Indexed: 11/17/2022] Open
Abstract
Reading is one of the essential processes during the maturation of an individual. It is estimated that 5-10% of school-age children are affected by dyslexia, the reading disorder characterised by difficulties in the accuracy or fluency of word recognition. There are many studies which have reported that coloured overlays and background could improve the reading process, especially in children with reading disorders. As dyslexia has neurobiological origins, the aim of the present research was to understand the relationship between physiological parameters and colour modifications in the text and background during reading in children with and without dyslexia. We have measured differences in electroencephalography (EEG), heart rate variability (HRV), electrodermal activities (EDA) and eye movements of the 36 school-age (from 8 to 12 years old) children (18 with dyslexia and 18 of control group) during the reading task in 13 combinations of background and overlay colours. Our findings showed that the dyslexic children have longer reading duration, fixation count, fixation duration average, fixation duration total, and longer saccade count, saccade duration total, and saccade duration average while reading on white and coloured background/overlay. It was found that the turquoise background, turquoise overlay, and yellow background colours are beneficial for dyslexic readers, as they achieved the shortest time duration of the reading tasks when these colours were used. Additionally, dyslexic children have higher values of beta (15-40 Hz) and the broadband EEG (0.5-40 Hz) power while reading in one particular colour (purple), as well as increasing theta range power while reading with the purple overlay. We have observed no significant differences between HRV parameters on white colour, except for single colours (purple, turquoise overlay, and yellow overlay) where the control group showed higher values for mean HR, while dyslexic children scored higher with mean RR. Regarding EDA measure, we found systematically lower values in children with dyslexia in comparison to the control group. Based on the present results, we can conclude that both pastel and intense background/overlays are beneficial for reading of both groups and all sensor modalities could be used to better understand the neurophysiological origins in dyslexic children.
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Affiliation(s)
- Tamara Jakovljević
- Jožef Stefan International Postgraduate School, 1000 Ljubljana, Slovenia
| | - Milica M. Janković
- School of Electrical Engineering, University of Belgrade, 11000 Belgrade, Serbia; (M.M.J.); (A.M.S.)
| | - Andrej M. Savić
- School of Electrical Engineering, University of Belgrade, 11000 Belgrade, Serbia; (M.M.J.); (A.M.S.)
| | - Ivan Soldatović
- Institute of Medical Statistics and Informatics, Faculty of Medicine, University of Belgrade,11000 Belgrade, Serbia;
| | | | - Tadeja Jere Jakulin
- Faculty of Tourism Studies, University of Primorska, 6320 Portorož, Slovenia;
| | - Gregor Papa
- Computer Systems Department, Jožef Stefan Institute, 1000 Ljubljana, Slovenia;
| | - Vanja Ković
- Laboratory for Neurocognition and Applied Cognition, Faculty of Philosophy, University of Belgrade, 11000 Belgrade, Serbia;
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