# A Wireless EEG System for Neurofeedback Training
## 5 Discussion  
The proposed EEG system design, which is easily scalable and adaptable to various EEG tasks, explored the \(\alpha/\theta\) z-NF effects during discrimination of different contrast LSF illusions on children with DD. Mechanisms compensating parvo- or magnocellular deficits were induced during the qEEG z-NF training. By simultaneously reducing excess \(\theta\) frequencies and increasing power at the \(\alpha\) frequencies, these mechanisms normalized the frequency power spectrum associated with the specific experimental conditions. Specific frequency changes, such as decreased \(\alpha/\theta\) scores and \(\alpha\) oscillations, were found in the posterior areas of the right hemisphere. Other changes under increased \(\alpha/\theta\) scores (e.g., \(\theta\) activity decrease and \(\alpha\) activity increase) were observed in the anterior areas. The postD group was characterized by emphasized \(\alpha/\theta\) (\(\alpha\) power) increases at the posterior regions in the left brain hemisphere compared with the other groups. Low pre-D \(\alpha/\theta\) scores were observed during the first NF sessions from the left MOG to the MFG (low-contrast LSF illusions) and from the left MTG to the ATG (high-contrast LSF illusions). Recent NF training sessions resulted in higher post-D \(\alpha/\theta\) scores at the left MOG across the SPL to the PRECG (low- and high-contrast conditions). The reading skills were also improved after NF training of children with disabilities in learning (Table S2). Studies of EEG-based NF have shown that the combination of qEEG-zNF and other treatment approaches leads to better outcomes than an NF alone [36]. Combining the training effect of NF on the primary visual deficit of DD with the effects of visual perceptional training on specific visual deficiencies for dyslexia [33; 36] improved reading by stimulating the connectivity of weakly connected brain regions in the reading network. The design of the EEG system was convenient to apply in schools. Although the additional visual training for specific DD deficits extended the training period, it still fell short of age-related maturation. Therefore, the NF contribution of the protocol to improving the cognitive and reading skills of children with DD was combined solely with the contributions of the visual training and could not be attributed to age-related maturation or other school learning. The precentral, left ATC, SPL (precuneus), and lateral occipital cortex showed significant changes as a result of training in the postD group. The changes in the middle occipital cortices and the precuneus were significantly affected by the task features. Under the discrimination conditions, the SMA and the postcentral cortex reduced their activation, as did the bilateral precuneus, revealing the sensorimotor and visual processing deficits in the preD group, respectively. During reading tasks, reduced activation was also found in the SMA and the right IPL in the DD group [6]. The increased activity in the IFG and ATC in the preD group could be explained by more executive efforts and the low automation of the tasks (LSF illusion and reading). The reduced activity extending posteriorly from the right postcentral cortex to the SPL in children with DD (vs. the controls) could explain the reduced reading speed, occurring due to insufficient sensory feedback. The reduced activity in the right dorsomedial parietoocipital, bilateral preparietal, and superior parietal regions and the MOG of the preD group, compared with the controls, could be related to insufficient processing of visual-spatial information. The effective sensory stimulus processing and selective attention of the post-training dyslexics (for the high-contrast condition) and the controls (for the low-contrast discrimination) could be related to the decreased \(\alpha\) frequency power and \(\alpha/\theta\) activity in the occipital areas [37; 38], as well as in the frontoparietal network (high \(\theta\) frequency activity).