Author: Jessica Cipolla
Cipolla, Jessica, 2021 Lasting impact of LORETA z-score neurofeedback therapy on phonological dyslexia, Flinders University, College of Education, Psychology and Social Work
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Developmental dyslexia is a neurological disorder that results in poor language-related learning despite average intelligence: this includes behavioural symptoms such as poor reading, spelling, and decoding abilities. In addition to these behavioural symptoms, electroencephalography (EEG) research and new data analytic techniques make it possible to investigate alterations in neural networks that correlate with such symptoms. In this thesis, these alterations were assessed by examining their impact on the EEG field activity associated with neural function.
In an initial study, the EEG signatures of a sample of children with dyslexia with marked phonological impairment (phonological dyslexia) were obtained from a relatively large cohort of children with dyslexia and were compared to individually matched control participants. Results indicated that, relative to healthy controls, dyslexia was found to be associated with reduced power of delta, theta, alpha1, alpha2, beta2 and gamma frequency bands in frontal and temporal regions. In contrast, the power in these frequency bands was enhanced in the central and parietal-occipital electrodes. The gamma activity was consistently reduced in participants with dyslexia across all brain regions. Finally, all behavioural measures of dyslexia (6 reading tests, 3 phonological and 2 spelling tests) showed a consistent negative correlation with age of participants with dyslexia. This indicated that participants with dyslexia were continuously falling behind the normative age-expected behaviour at a near-constant rate. Consequently, the observed behavioural deficiencies translated into psychophysiological correlates that replicated some previous findings.
Various methods have been developed to improve the symptoms of dyslexia (e.g., phonological therapy, reading therapy). A promising neuroscience-based method is neurofeedback therapy. Neurofeedback has shown a positive effect in the treatment of symptoms of other disorders (e.g., ADHD, autism, epilepsy); however, research on neurofeedback in dyslexia is both scarce and inconsistent. Neurofeedback was shown to improve reading and phonological skills, but other studies did not observe any significant effects of neurofeedback in this disorder or found symptoms-unspecific effects (e.g., reduced aggression). Therefore, Study 2 was conducted to examine the effect of neurofeedback in participants with dyslexia. Following Study 1, participants with dyslexia from the baseline study were randomly split into therapy and control groups, and a treatment study was then conducted to assess the impact of LORETA z-score neurofeedback therapy on behavioural and neurological markers of dyslexia. Specifically, the therapy group received 20 sessions of neurofeedback therapy, and the waitlist control group of participants with dyslexia did not. The post-therapy assessment revealed that there were therapy-related improvements in phonological task performance and phonological spelling. Finally, EEG power increased across the frequency spectrum when measured over the frontal lobe, possibly reflecting involvement of reading-related frontal lobe structures.
Notably, the behavioural gains from therapy were retained three months post-treatment. An additional assessment of behavioural task performance showed that participant's performance was as improved as immediately following the end of the therapy and had improved even further in reading, phonological and spelling tasks. Further, performance benefits were present even when corrected for chronological age in reading and phonological (but not spelling) tasks. These findings provided novel evidence that the use of neurofeedback is an effective treatment for phonological dyslexia. It was therefore concluded that the positive effects of neurofeedback in dyslexia are lasting. However, future studies should examine whether such improvements could last longer than three months.
Keywords: neurofeedback, dyslexia, LORETA, z-score neurofeedback, EEG, qEEG, alpha, IAF, individual alpha peak frequency, phonological processing, treatment for dyslexia, time-frequency, clinical psychology, neural correlates, clinical trial
Subject: Psychology thesis
Thesis type: Doctor of Philosophy
Completed: 2021
School: College of Education, Psychology and Social Work
Supervisor: Richard Clark