# Neurofeedback Effects on EEG Connectivity among Children with Reading Disorders: I. Coherence
### NFB Studies Using Theta/Alpha Reduction Protocol  
Four experiments using the NFB protocol reinforcing a reduction in the theta/alpha ratio at the most abnormal lead have been reported by the [PERSON] group. All children had learning disorders, most of them with impairments in reading and abnormally higher theta/alpha ratios. The first study [44] was a control pseudorandomized single-blind design with five children receiving NFB and five children (three of them with IQs lower than eighty) receiving a sham NFB treatment. Cognitive scores only improved in the NFB group. Children showed an absolute power (AP) reduction in all bands at several leads, and only alpha RP at T6 increased. The two-year follow-up [55] showed that the EEG maturational lag in the control group increased, reaching abnormally high theta values; however, there were no positive behavioral changes, and the neurological diagnosisremained a learning disorder. Some children (more in the experimental group) showed improvements in memory, attention, self-esteem, and school achievement, as reported by parents. In contrast, in the NFB group, EEG maturation continued and was accompanied by positive behavioral changes, which were reflected in the remission of LD symptoms in four children. An unexpected result was the reduction in verbal IQ in the NFB group, which was attributed to their low socioeconomic status. The second study [45] included eleven children receiving NFB treatment (six plus the previous five) and the previous five children receiving sham NFB treatment. All the children in the NFB group learned to decrease their theta/alpha ratios during the course of the NFB sessions, and their cognitive scores improved. In this study, EEG current sources were reported because they represent the brain generators of the EEG observed at the scalp, and by calculating current sources, two of the undesirable effects inherent in EEG recorded on the surface are notably corrected: the effect of the reference is removed, and the effect of the conductive volume is considerably reduced, which makes current sources a more reliable measure of brain activity. In addition to using a more reliable measure, this study aimed to confirm a phenomenon that was previously observed by this group [44] and reported by other authors [56; 57]: immediately after NFB, changes in behavior were observed in the absence of changes in the EEG of the scalp. By using the current sources, [PERSON] et al. [45] were able to find some changes immediately after treatment in the NFB group (delta reduction in the right occipitotemporal gyrus and alpha increase in the left anterior cingulate and occipital gyri); however, two months later, not only were some of these changes sustained, but an important reduction in delta and theta frequencies emerged in the frontal, temporal, occipitotemporal, cingulate, and parahippocampal gyrus regions, mainly in the left hemisphere, as was an increase in alpha and beta in similar areas, but with right predominance. The number of changes observed coincided with the learning of the NFB since immediately after the NFB, only 4 of the 11 children managed to show a reduction in the theta/alpha ratio. However, two months later, it was achieved by seven children. In the control group, no significant differences were observed in the EEG current sources. The aim of the third study [46] was to explore whether the sensory modality of the reinforcer (auditory or visual) induced differences in the outcomes of NFB treatment aimed at reducing the theta/alpha ratio. For this, 10 children received an auditory reward (with eyes closed), and another 10 were given a visual reward (with eyes open). In both NFB groups, the theta/alpha ratio in the most abnormal lead was reduced, AP and RP decreased in the delta and theta bands at several leads, and an increase in the alpha band was observed in almost all leads. In the beta band, the NFB-auditory group showed some increases, while the visual-NFB group only showed an increase in Cz.