frequency bands
Research Papers
Neurofeedback for ADHD: a review of current evidence
Considerable scientific effort has been directed at developing effective treatments for attention-deficit/hyperactivity disorder (ADHD). Among alternative treatment approaches, neurofeedback has gained some promising empirical support in recent years from controlled studies as a treatment of core ADHD symptoms. However, a recent stringent meta-analysis of 8 randomized controlled trials published in 2013 found that the effects were stronger for unblinded measures and 3 recent subsequently published well-controlled trials found no effects for the most blinded ADHD outcome. Firmer conclusions must await upcoming evidence from larger controlled studies and future meta-analyses contrasting different forms of neurofeedback and different outcome measures.
View Full Paper →Application of Neurofeedback in General Neurology Practice
Neurofeedback (NFB), also called EEG biofeedback, is infrequently applied in general neurology practice. Therefore, this study was conducted to evaluate the clinical usefulness of NFB in neurological settings. Over the period of approximately 15 months, 25 subsequent patients who were interested in NFB therapy and completed at least 20 sessions of NFB treatment were analyzed for potential clinical benefits. Patients’ subjective responses were collected after NFB treatment to see if any improvement of symptoms was accomplished with NFB therapy. Quantitative electroencephalography (QEEG) was completed before and after NFB therapy initiation and analyzed for any major changes in frequency bands expression. Patients’ analysis revealed 84% subjective improvement rate and 75% objective QEEG improvement after completion of NFB therapy. These encouraging results indicate the need for more broad utilization of NFB in general neurology practice.
View Full Paper →Annotation: Neurofeedback – train your brain to train behaviour
Background: Neurofeedback (NF) is a form of behavioural training aimed at developing skills for self-regulation of brain activity. Within the past decade, several NF studies have been published that tend to overcome the methodological shortcomings of earlier studies. This annotation describes the methodical basis of NF and reviews the evidence base for its clinical efficacy and effectiveness in neuropsychiatric disorders. Methods: In NF training, self-regulation of specific aspects of electrical brain activity is acquired by means of immediate feedback and positive reinforcement. In frequency training, activity in different EEG frequency bands has to be decreased or increased. Training of slow cortical potentials (SCPs) addresses the regulation of cortical excitability. Results: NF studies revealed paradigm-specific effects on, e.g., attention and memory processes and performance improvements in real-life conditions, in healthy subjects as well as in patients. In several studies it was shown that children with attention-deficit hyperactivity disorder (ADHD) improved behavioural and cognitive variables after frequency (e.g., theta/beta) training or SCP training. Neurophysiological effects could also be measured. However, specific and unspecific training effects could not be disentangled in these studies. For drug-resistant patients with epilepsy, significant and long-lasting decreases of seizure frequency and intensity through SCP training were documented in a series of studies. For other child psychiatric disorders (e.g., tic disorders, anxiety, and autism) only preliminary investigations are available. Conclusions: There is growing evidence for NF as a valuable treatment module in neuropsychiatric disorders. Further, controlled studies are necessary to establish clinical efficacy and effectiveness and to learn more about the mechanisms underlying successful training.
View Full Paper →Effects of Central Cortical EEG Feedback Training on Incidence of Poorly Controlled Seizures
Summary This study examined the clinical effects of central cortical EEG feedback training in 8 patients with poorly controlled seizures. After base‐line recordings, patients were trained in the laboratory and then initiated on a double or triple crossover design using portable equipment at home, with bimonthly laboratory test sessions. Performance at home was monitored by a strip chart recorder with the portable unit. Training was based on the simultaneous detection of two central cortical (C 3 ‐T 3 ) EEG frequency bands (6–9 Hz and either 12–15 or 18–23 Hz), with reward provided for the occurrence of one in the absence of the other. The design consisted of successive 3 month periods of training, with reward contingencies reversed after each period without the subject's knowledge. Seizure incidence records were compared statistically before, during, and after the design. Six of the 8 patients reported significant and sustained seizure reductions, which averaged 74%, following reward for either 12–15 or 18–23 Hz in the absence of 6–9 Hz. Response to positive reward for 12–15 Hz was specific, with seizure rates returning to base line when reinforcement contingencies were reversed. Reduced seizure rates following positive reward for 18–23 Hz were not altered with contingency reversals. A nonspecific interpretation of these effects is rejected in favor of an EEG normalizing hypothesis. RÉSUMÉ Cette étude envisage les effets cliniques de lapprentissage par rétroaction biologique (biofeedback) à renforcer l'EEG des régions centrales chez 8 épileptiques dont les crises étaient mal contrôlées par la thérapeutique. L'apprentissage a eu lieu au domicile des malades après un entrainement initial puis des contrôles bimensuels au laboratoire. L'unité portative comprenait un enregistreur sur papier pour surveiller la performance du malade. L'apprentissage avait pour but de permettre aux sujets de reconnaiire simultanément deux bandes de fréquences de l'EEG de la région centrale (6–9 Hz et 12–15 ou 18–23 Hz), la récompense étant donnée en présence d'une de ces fréquences et en l'absence de l'autré. On a utilise des périodes successives d'apprentissage durant 3 mois, avec une inversion des récompenses après chaque période, les inversions étant faites à l'insu du sujet. La fréquence des crises a été comparée statistiquement avant, pendant et après l'expérience. Six des huit malades ont rapporté une réduction significative de la fréquence des crises, avec une moyenne de 74%, dans le cas d'une récompense pour 12–15 ou 18–23 Hz en l'absence de 6–9 Hz. La réponse à une récompense positive pour 12–15 Hz était spécifique, avec un retour à la ligne de base lors de l'inversion des récompenses. La réduction de frequence des crises après une récompense positive pour 18–23 Hz n'a pas changé avec l'inversion des récompenses. L'interprétation non‐spécifique de ces résultats est rejetée, en faveur de l'hypothèse dune normalisation de l'EEG. RESUMEN En este estudio se han examinado los resultados clinicos en un grupo de ocho epilépticos mal controla‐dos que habian sido entrenados para la realización de un feedback electroencefalográfico central cortical. Después de practicar los registros de control, los enfermos fueron entrenados en el laboratorio y, posteriormente, iniciados en un plan de investigacibn con doble o triple superposición utilizando, en su domicilio, un equipo portatil de registro y estudios bimensuales en el laboratorio. Los resultados obtenidos en el domicilio se registraron en un registrador en banda portatil. El entrenamiento se basó en la detec‐ción simultánea de dos bandas de frecuencias elec‐troencefalograficas corticales centrales (C 3 ‐T 3 ) de 6–9 Hz y también de 12–15 6 18–23 Hz, dando una recompensa al sujeto cuando una banda de frecuencia apareciera en ausencia de la otra. El plan utilizado consistió en tres periodos sucesivos de entrenamiento, de tres meses cada uno, con contingencias de recompensa alternadas en cada periodo sin conocimiento del sujeto. Los registros de incidencia de los ataques se compararon estadisticamente antes, durante y después del plan. Seis de los ocho enfermos mostraron una reducción significativa y mantenida de los ataques que promedió un 74%, tras la recompensa de 12–15 ó 18– 23 Hz, en ausencia de 6–9 Hz. La respuesta a la recompensa positiva para 12–15 Hz fué especifica, con restauración de la frecuencia de ataques a los niveles previos cuando el refuerzo de las contingencias se alternaba. La reducción de la frecuencia de ataques conseguida con la recompensa positiva para 18–23 Hz no se modificó con la inversión de las contingencias. En favor de la hipótesis de la normalización del EEG se rechaza una interpretación inespecifica de los efectos descritos. ZUSAMMENFASSUNG Untersuchung über die klinischen Wirkungen des zentralen corticalen EEG feedback Trainings bei einer Gruppe von 8 schlecht kontrollierten Epileptikem. Nach Ableitung des Ausgangs‐EEGs wurden die Patienten im Labor geschult. Dann begann eine ambu‐lante Doppel‐ oder Dreifachcrossover‐Studie mit einer tragbaren Ausrilstung und 2‐monatlichen Labortests. Das Verhalten zu Hause wurde durch Lochstreifen‐aufzeichnungen mit der tragbaren Einheit festgehalten. Das Training beruhte auf der gleichzeitigen Ent‐deckung von 2 corticalen (C 3 ‐T 3 ) EEG‐Frequenz‐bandern(6‐9Hzundentweder 12–15 oder 18–23 Hz) mit Belohnungen fur das Erscheinen des einen in Abwesenheit des anderen Frequenzbandes. Der Ver‐suchszeitraum bestand aus aufeinanderfolgenden 3‐Monatstrainingsperioden mit Belohnungsquoten, die nach jeder Periode ohne Wissen des Patienten umge‐kehrt wurden. Die Häufigkeit der Anfälle wurde aufgezeichnet und statistisch verglichen vor während und nach dem Versuch. 6 von 8 Patienten berichteten signifikante und anhaltende Anfallsreduktionen (im Durchschnitt 74%) nach einer Belohnung für entweder 12–15 oder 18–23 Hz in Abwesenheit von 6–9 Hz. Die Reaktion auf eine Belohnung fur 12–15 Hz war spezifisch; die Anfallshäufigkeit kehrte zum Aus‐gangswert zurück, wenn die Verstärkerantwort umge‐kehrt wurde. Eine veränderte Häufigkeit nach Belohnung für die Erkennung von 18–23 Hz wurde nicht durch Umkehr der Belohnung geändert. Eine Interpretation dieser Wirkungen als nicht spezifisch wird zu Gunsten einer Hypothese der EEG‐Normalisierung zürtickgestellt.
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