Neurofeedback Training for Dyslexia

Dyslexia is a learning disability with difficulty in recognition/reading and language processing abilities, often observed with symptoms occurring from childhood, which furthers persist in life. Children with dyslexia have learning difficulties in their academics with cognitive and behavioural challenges. It is often associated with disability in readings, but the neural attributes of differential brain activities can be observed before the individual acquires the skill.

Learning the skill of reading requires focus on both audio and visual attention to the stimuli, with learning the phonological comprehension of words. This comprehensive task requires intense mental activity including working memory or processing speed. Studies have shown that in patients with dyslexia, phonological processing is the primary deficit observed which further disrupts functions like reading, phonological awareness and abilities to form verbal memory. This is explained by the phonological deficit theory suggesting that dysfunction of peri-sylvan region which is associated with language consisting of areas like Wernicke’s and Broca’s area is correlated to phonological difficulties observed in dyslexia.

There are certain theories based on different experiments focusing on certain regions, but recent advancements to neural-investigative techniques have suggested that dyslexia is linked to dysfunction of executive functions (Farah et al., 2021). More recently, with modern investigation using neurofeedback and related experiments, a correlation between dyslexia and reduced functionality in executive performance has been stated. Executive functions develop in children from birth till the age of twenties and reading is tightly connected to this development.

Brain wave activity in dyslexia

Studies have suggested that during reading tasks for adults with dyslexia, under-activation of the left hemisphere specifically the temporal-parietal region of the cortex (T5 and P3) is observed along with overactivity in right hemisphere associated with functions like retrieval, language processing, attention and working memory hence resulting in reading difficulties. The under-activation of left side is only observed in adults whereas right hemisphere overactivity has been observed in children as well (Cancer et al,2021). However, a study also reported that beta in right parietal region and occipital regions is observed to be low during reading tasks alongside increased activation of slow waves in the frontal right (F8) and high beta at frontal left hemisphere (F7) of the brain (Breteler M. H. et al., 2010).

Brain activity can be determined by categorising into five brain waves i.e., delta (0.5–4 Hz), theta (4–7 Hz), alpha (8–12 Hz), beta (13–30 Hz), and gamma (>30 Hz) serving specific functions like perception, attentional outputs, sensory motor and cognitive functions. Alpha band activity is associated with information pressing activity and is one of the dominant frequencies in brain. Delta band is linked with deep state and internal concentration. Beta activity is a significant rhythm not associated to one particular function, as serving cognitive performance overall. The gamma activity is found high during speech tasks interacting with other bands during cognitive tasks (Cainelli et al., 2022).

Studies demonstrate that children with dyslexia consume higher energy leading to increased beta frequency in temporal – parietal cortex of the brain (TPC), during writing tasks (Perera et al., 2018). The study conducted by Penolazzi (2008) stated the increased theta activity in individuals with developmental dyslexia which further leads to maturational lag in the group. Maturational lag can be described as developmental delay in cognitive performance which is observed in ADHD and dyslexia.

It has also been shown that high slow-wave activity (delta, theta) at TPC can result in higher possibilities of cognitive impairments, structural lesions and maturational lag (Seshadri et al., 2022). Therefore, the principle of neurofeedback protocols for dyslexia is to increase beta frequencies (fast waves) and reduce the theta activity (slow waves) at the TPC to address abilities like attention, visual perception and motor outputs.

Neurofeedback effect on dyslexia challenges

There are various techniques proposed by research to learn about challenges in dyslexia. It can be classified into behavioural, brain imaging and eye movement-based experiments. The behavioural tests are the conventional method to study the symptoms of dyslexia using a standardised set of tests. The brain imaging techniques used are magnetic resonance imaging (MR), electroencephalography (EEG) or positron emission topography (PET) (Perera H et al. 2018). EEG is one of the popular methods used to determine brain wave activities in people with dyslexia.

EEG- Neurofeedback training is a non-invasive training method used to encourage desired brain activity in adults and children with dyslexia. During this training procedure, the scalp is firstly incorporated with EEG electrodes. These electrodes measure the brain activity of specific regions and in return receive the feedback in both audio and visual form. The parameters are set on the software to the desired state i.e., the principle of increasing beta activity and decreasing theta activity in pre-frontal areas of the brain. A neural finding conducted by Seshadri, N. P. G et al., 2022 showed a significant reduction in theta activity at frontoparietal temporal sites along with decreased theta strength at temporal parietal occipital regions during a task for the dyslexic group which shows the activities behind poor task performance. When the set parameters are closely met that’s when the client receives positive feedback from the screen in front.

Studies have shown that increasing frontal beta to theta ratio can improve phonological awareness in patients (Cancer et al.,2021). Training protocols are set in relation to the developmental requirements of the client which is, for example, improving attention and visuo-motor abilities for developmental dyslexia.

The use of neurofeedback training for dyslexia, both for adults and children, is a promising filed of research with various experimental conducts ongoing currently. Studies have shown to enhance brain activity towards desirable state along with reducing dysfunctional mechanisms using this technique (Table 1).

ADHD and dyslexia, sharing common neural mechanisms, have also similar principles for some NF training protocols, i.e., increasing β/ θ ratios to enhance both motor and visual abilities with brain training at C3 and C4 (Cancer et al., 2021). Recently, individual protocol based approached was used by Eroglu et al. (2020) reducing theta frequencies for different regions. A study applied the neurofeedback training, aiming to increase β/ θ ratios over site C3 and C4 and carried neuropsychological assessments to record pre and post NF training results. A comparison was drawn showing improved phonological awareness and auditory vigilance in the participants with dyslexia (Table 1) (Au et al., 2014).

Similar study using the protocols was carried out by Sadeghi and Nazari (2015) focusing on visuo-spatial attention. They targeted O1 and O2 locations which is a posterior region of the brain related to visual skills and recorded behavioural improvements after the training. The results showed decrease in reaction times along with increased accuracy of responses.

Interestingly, a research paper mentioned a study of NF training in patients with dyslexia with an aim to reduced theta waves at both Broca’s and Wernicke regions of the brain associated with speech and language processing. The study document that post-NF training, the lower complexities of children with dyslexia increased to a typical developing group’s levels. (Table 1)

Table 1: Types of studies conducted using neurofeedback training for dyslexia

NF training in children vs adults

Dyslexia is a disorder with reading problems with an early onset from childhood. Affected neuroplasticity is not only observed in children but in adults as well (Hernández-Vásquez R. et al.,2023). Studies have been conducted on dyslexia using behavioural tests, neuroimaging method and functional imaging to learn about executive dysfunction in people with dyslexia. From children to adults, the abnormality in executive functions is observed along time (Table 2) (Farah R, Ionta S and Horowitz-Kraus T, 2021).

Brain imaging finding show during reading related phonological tasks in adults, the population over 22 years exhibits hyperactivity in geniculate body along with hypoactivation in left occipital temporal region, left inferior and hyperactivity of occipital regions. Whereas children (6-12 years) show hypoactivity of Wernicke’s’ region and fusiform gyrus along with hyperactivation in basal ganglia and inferior frontal gyrus during reading related tasks (Farah et al., 2021).

Using neurofeedback training has shown positive results in improved spelling, attention and reading abilities of the children (table 1).

Breteler (2010) conducted research examining the improvements in children with dyslexia and specifically looked at reading and spelling. They were able to find a significant improvement in spelling for the children that received the neurofeedback training when compared to the control group that did not receive the neurofeedback training. Also, their findings suggest that improvement in attentional processes in the brain could be partially what is contributing to the spelling improvements (Breteler, 2010).

A brain research finding has mentioned NF training on adults with dyslexia targeting temporal parietal activation. The post training results proved that NF training can restore the inter-hemispheric balance related to reading abilities in adults with dyslexia as post training the participants showed improvement in reading related functions (Table 1) (Cancer et al.,2021).

For adults with dyslexia, depending on different neural conditions, therapists can also advise neurofeedback training for improving attentional and memory deficits along with transcranial magnetic stimulation to facility plasticity in brain (Hernández-Vásquez R. et al., 2023).

Table 2: Studies conducted in different age groups determining the executive dysfunctions at different ages.

Conclusion

Dyslexia is a neurological disability with massive impact on population affected. It can cause difficulties in performance, reading abilities and within skills. This article focusses EEG based neurofeedback training carried to bring desired impacts.

Neurofeedback is a non- invasive approach to improve the cognitive deficits in people with dyslexia. Research has shown improvements with memory, ability to spell, reading and writing tasks for children with dyslexia.

As the regions associated with cognitive deficits in dyslexia are mainly frontal and temporal parietal regions, focusing on specific targeted sites and training beta and theta ratios during the NF training has shown enhancement in visual and auditory attention along with phonological awareness.

Future studies are focusing upon increasing sample sizes and individual based protocols to learn better abut developmental changed in dyslexia along with genetic research as another intriguing field of research to learn about heritable relationships of functional and structural framework of the genes. As proven by research neurofeedback increases positive and helpful connections in the brain offering support to the development of brain communication in patients with dyslexia.

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