EEG activity
Research Papers
Train Your Brain? Can We Really Selectively Train Specific EEG Frequencies With Neurofeedback Training
Neurofeedback (NFB) is an operant conditioning procedure whereby an individual learns to self-regulate the electrical activity of his/her brain. Initially developed as a treatment intervention for pathologies with underlying EEG dysfunctions, NFB is also used as a training tool to enhance specific cognitive states required in high-performance situations. The original idea behind the NFB training effect is that the changes should only be circumscribed to the trained EEG frequencies. The EEG frequencies which are not used as feedback frequencies should be independent and not affected by the neurofeedback training. Despite the success of sensorimotor rhythm NFB training in cognitive performance enhancement, it remains unclear whether all participants can intentionally modify the power densities of specifically selected electroencephalographic (EEG) frequencies. In the present study, participants were randomly assigned to either a control heart rate variability (HRV) biofeedback (HRV) training group or a combination of HRV biofeedback and neurofeedback (HRV/NFB) training group. This randomized mixed design experiment consisted of two introductory theoretical lessons and a training period of 6 weeks. We investigated the evolution of the different EEG frequency bands of our two experimental groups across and within session. All the participants exhibited EEG changes across and within session. However, within the HRV/NFB training group, untrained EEG frequencies have been significantly modified, unlike some of the trained frequencies. Moreover, EEG activity was modified in both the HRV group and the HRV/NFB groups. Hence, the EEG changes were not only circumscribed to the trained frequency bands or to the training modality.
View Full Paper →Effects of Neurofeedback Training on Inhibitory Capacities in ADHD Children: A Single-Blind, Randomized, Placebo-Controlled Study
Studies performed during the last decades suggest that neurofeedback (NF) training can effectively reduce symptomatology in children with Attention deficit hyperactivity disorder (ADHD). Yet questions remain concerning specific effects of NF training in ADHD children, because these studies did not use a randomized, placebo-controlled approach. To address this issue, such an approach was used in the present study to measure the impact of NF training on inhibitory capacities. Method. Nine ADHD children (with no comorbidity), aged 8 to 13 years, were randomly assigned to either an experimental group (n1/45) or a placebo group (n1/44). For both groups, training protocols comprised 40 one-hr sessions (20 meetings of 2 sessions each). Sensorimotor rhythm=Theta training was used in the experimental group. Prerecorded sessions of the first author's EEG activity were used in the placebo group. Pre- and posttraining assessments consisted of the Conner's Parent Rating Scales (CPRS-R) and neuropsychological tests. A multiple case study strategy was applied for data analysis using a Reliable Change Index when applicable. Results. One experimental participant was a dropout, and one placebo participant had to be discontinued due to adverse effects. The latter participant accepted to undergo posttraining evaluations; hence an Intention-to-Treat analysis was performed on this participant's data. Remaining participants showed significant improvements on the CPRS-R. Improvements were measured on the Variability measure of the CPT-II consistently across the placebo group and on the Inhibition Condition of the Stroop Task for all but one placebo participant. The same trend was found for the Inhibition=Switching Condition (Stroop Task) across the experimental group (n1/44). Conclusion. The small sample size precludes from evaluating specific neurofeedback effects. Still, the presence of placebo responses suggests that other factors, such as motivation or expectations, might contribute to the outcome of NF training in children with ADHD.
View Full Paper →Neurofeedback for AD/HD: A Ratio Feedback Case Study and Tutorial
The case study of a 13-year-old AD/HD male treated with neurofeedback is the subject matter for a tutorial on Ratio feedback. Method. Neurofeedback was conducted at C3 (increase 15 to 18 Hz, decrease 2 to 10 Hz) and C4 (increase 12 to 15 Hz, decrease 2 to 7 Hz). Protocols provided visual and auditory feedback based on the ratio of slow wave activity to be suppressed divided by fast wave activity to be enhanced (Ratio feedback). Results. The patient demonstrated marked improvement in processing speed and variability on the Test of Variables of Attention-Auditory, a 19-point increase in IQ on the Kaufman Brief Intelligence Test, significant behavioral improvement based on parental (Behavior Assessment System for Children) and patient (Brown ADD Scale) reports, and a 7.5 grade equivalent increase in reading scores (Kaufman Test of Educational Achievement-Brief Form). At the 17-month follow-up parent questionnaires indicated that the patient's behavioral gains had been maintained or were slightly improved. EEG data showed significant declines in the C4/SMR Ratio (10*2 to 7 Hz/12 to 15 Hz) and 2 to 7 Hz amplitude, a tendency toward an increase in 12 to 15 Hz amplitude, a significant increase in 8 to 11 Hz amplitude, and a decline in 22 to 30 Hz amplitude. Beta activity (15 to 18 Hz) was unchanged. An unexpected finding was that C3/Beta (10*2 to 10 Hz/15 to 18 Hz) and C4/SMR protocols had similar effects on the EEG even though they targeted different bands to enhance and suppress. It appears that suppression of slow wave activity (2 to 7 Hz) may be the active component in both Ratio protocols and that fast wave enhancement either plays a minor (12 to 15 Hz) or no role (15 to 18 Hz). Discussion. The findings cast doubt on the assumption that the C3/Beta and C4/SMR protocols have unique effects on EEG activity. Nevertheless, they may have differential effects on brain functions related to the training sites employed. It would be useful to analyze EEG changes in successfully treated individual AD/HD patients as a first step toward understanding the effects of various treatment protocols. What the protocols are intended to do, and the actual effects on the EEG may be different. If there are active components common to the various AD/HD treatment protocols reported in the literature, this is one way of beginning to recognize them. Brain maps collected before, during, and at the conclusion of treatment would enhance our understanding of treatment effects of various neurofeedback protocols, lead to more focused and productive research, and ultimately facilitate the development of more efficient treatment paradigms.
View Full Paper →Neurofeedback training as a therapy for tinnitus/ Neurofeedback in der Therapie des Tinnitus
Background and objective: Biofeedback is known as a possibility to control physiologic processes like body temperature or heart frequency. Neurofeedback is a form of biofeedback linked to aspects of the electrical activity of the brain such as frequency, location or amplitude of specific EEG activity. It has been successfully used in patients with closed head injury, hyperactivity disorder or epilepsy. Patients/methods: In this study 40 patients with tinnitus were treated with neurofeedback. They trained to upregulate the amplitude of their α-activity and downregulate the amplitude of β-activity during muscle relaxation and acoustic orientation on sounds or music in order to suppress their tinnitus. Results: After 15 sessions of training 24 patients with a duration of their tinnitus for an average of 1 year showed significant increase of α-amplitudes while 16 patients with duration of their tinnitus on an average of 7 years showed a decrease of β-amplitudes without any change in α-activity. After the training all patients had a significant reduction of the score in the tinnitusquestionaire of Göbel and Hiller. In a control-group of 15 persons without tinnitus we didn't see any changes of α- or β-amplitudes during the same training. Conclusions: In conclusion neurofeedback is a new therapy for patients with tinnitus. Patients get the possibility of selfcontrol and therefore of influence on their disease.
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