Relations between diseases and the EEG are not simple. They often depend on the power of certain frequencies in a special part of the brain. Not only the frequencies but also the a-symmetrie of waves (different power in right/left hemisphere) is important. EEG patterns are not the cause of illness but the reflexion of a underlying disorder. For example while meditating the brainwaves change because the underlying mindset and focus of attention changes.
What is the qEEG ?
The qEEG (Quantitative EEG) is a map of the avarage wave-powers as measured in a group of people.
These are dependant on age (children have a different wave pattern) and also related to a specific task like the eye-open condition while reading, listening or drawing.
The qEEG for example of childeren with ADHD can be compared to a healthy controle group of the same age. In ADHD you may find that the beta/theta power ratio is higher than average.
The difference in power of certain waves might vary between the right and left hemispere, again dependent on a specific task. This is calculated and expressed in the (a)symmetrie index.
Gamma waves and learning problems
High-frequency cortical activity in humans and animals has been linked to a wide variety of higher cognitive processes. This research suggests that specific changes in neuronal synchrony occur during cognitive processing, distinguished by emergence of fast oscillations in the gamma frequency range.
The researcher April Benasich found a connection between language problems in young children and the level of G-waves. The more waves, the better the language ability. It is not yet clear how they arise, but some studies indicate that they are coherent and occur when we have an AHA experience. Benasich also found that children with more G-waves could focus more.
These waves can be enhanced by biofeedback. According to Benasich, Gamma waves are important for understanding spoken and written language. They are able to register when the child listens to a tone that suddenly changes.
If the pattern of brain waves changes briefly and shows a valley then that wave-valley is an AHA experience where the brain detects a change. The more AHA experiences the greater language ability in children. In children with low language ability this can be trained by recording changes in pitch more clearly.
Note: Thus we create "consciously directed attention" as opposed to "outward drawn attention".
Alcoholism and axiety
An alpha-theta brainwave training has been used in the treatment of alcoholism and axiety. This low frequency training differs greatly from the high frequency beta and SMR training. Alpha-theta training, involves accessing of painful or repressed memories through the alpha-theta state. Subjects completed 15 30-min sessions (15 keer) of alpha-theta biofeedback training. These experimentally treated alcoholics showed sharp reductions in self-assessed depression (Beck's Depression Inventory).
Serum beta-endorphin is a neuropeptide and is an index of stress. Brainwave treatment appears to counteract the increase in circulating serum beta-endorphin levels.
Neurofeedback has been studied most extensively in Attention Deficit Hyperactivity Disorder, for which at least 5 randomized controlled trials with mixed results have been published. Reference: Bink M, van Nieuwenhuizen C et al: Neurocognitive effects of neurofeedback in adolescents with ADHD: A randomized controlled trial. J Clin Psychiatry 75:535-542, 2014
Research has shown that many patients with ADHD have more slow wave (theta in particular) activity in their resting EEG spectral analysis than normal controls, and they also have less beta wave activity especially in the central and frontal regions (Lofthouse, Arnold, Hersch, Hurt, & Debeus, 2012).
In Getting rid of Ritalin (Hall) neurofeedback is used teaching patients to overcome the slow brain wave activity that is at he core of ADD.
Autism and Gamma sub band (35 to 45 Hz range)
Every study on gamma frequencies in autism has shown abnormalities, especially those around 40 Hz frequencies. This may correlate with human perceptual binding and attention. The 35 to 45 Hz range gamma sub-band is associated with the mechanisms of information processing such as sensory, working memory, attention, and other cognitive processes. Gamma oscillations in children with autism during attention tests where especially present at the frontal topographies. Gamma frequency abnormalities in autism can be considered as a neurophysiological, EEG-based biomarker of autism. Read More
This was investigated by Fleur Margeret Howells , Dan J. Stein (Department of Human Biology, Faculty of Health Sciences, University of Cape Town South Africa).
Materials and Methods
Fifty-three healthy adults completed the Childhood Trauma Questionnaire which assesses physical neglect, emotional neglect, emotional abuse, physical abuse, sexual abuse, and denial of childhood trauma. These individuals underwent cortical (electroencephalography) and peripheral (heart rate, skin conductance responses, and salivary cortisol) physiological recordings at rest (eyes open and eyes closed) and during performance of a visual go/no-go (GNG) task. Associations between reported childhood trauma and physiological measures were determined.
Physical and emotional neglect were correlated with decreased left parietal tonic ? band power during resting conditions and during the GNG task. Emotional abuse was correlated with decreased right frontal ? band power during rest, increased gamma band power during the GNG task, and cortisol at the end of the testing session. Physical and sexual abuse were correlated with delayed P300 latency and enhanced P300 amplitude during the no-go conditions of the GNG task. The denial scale was correlated with a decrease in gamma)and increase in ? band power during the no-go conditions of the GNG task.
The present study provides evidence that childhood trauma is associated with altered cortical arousal and that the pattern of this association is dependent on the form of childhood trauma experienced. Read full artcle at
Is anterior EEG alpha asymmetry a trait marker for depression?
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Literature : Peeters F, Oehlen M et al: Neurofeedback as a treatment for major depressive disorder ; a pilot study. PLoS One. 2014 Mar 18;9(3):e91837. doi: 10.1371/journal.pone.0091837. eCollection 2014