Neurofeedback - a Comprehensive Illustration
Basic Principles of Biological Feedback
During neurofeedback and all other methods of biofeedback, the consciousness is confronted with the unconsciousness. We try to influence processes deliberately, that are usually, subconsciously controlled by our brain. Here's an example: Try to lower your heart rate intentionally. This will probably be immpossible to accomplish without any sort of helping-device. If you perceive your heart rate continuously though, e.g. through a definite tone, you can learn to influence your heart rate within a couple of hours. Elmar Green, the pioneer of biofeedback made the following discoveries already in the 1970's:
- Every neurophysiological (contingent through nerves) function of a human, e.g. respiration, pulse, etc. is controlled by the brain. If the user receives a feedback which is a reinforced response through electric devices, he can influence thes functions.
- Every change in the physiological conditon correlates to a conscious or unconscious change in the mental and emotional area. Conversely, every conscious or unconscious change in the mental and emtotional area is accompanied by changes in the physiological section.
You have to be aware of something, before you can change or control it. Elmar Green, 1977
Brain Waves and Neurofeedback
Biological signals which we measure during neurofeedback, are called brain waves. Brain waves are exceptionally interesting and complex, physiological parameters. They can lead to a lot of conclusions but should not be overestimated.
The EEG is still one of the most important methods of diagnosis in neurology. Please note that the MindMaster® EEG is a dual-channel EEG-device, that should not be used for clinical diagnosis as epilepsy or other pathologies. We assume that there has already been a diagnosis (e.g. ADHD) to which the MindMaster® EEG can appeal to through neurofeedback-training.
During measurement of brain waves, following things among others should be considered.
- Where is measurement applied? (frontal, central, parietal, left, right);
- How is measurement applied? (monopolar, bipolar, single-channel, dual-channel);
- When is measurement applied? (during exertion, relaxation, sleep)
Measurement varies strongly, when influenced by one or more of these factors.
During appliaction of neurofeedback, there are several possibilities of influencing the brain waves of a user.
Amplitude and Frequency.
Here you see a raw signal in a EEG:
(Screenshot from our software "MindStream")
We notice the space of time of approx. one second (16-17) on the X-axis and an amplitude in the area of about -20 to +20 µV on the Y-axis. But as you can see no clearly-cut frequency can be identified. Parts of frequency rather overlap each other in the raw signal. We see large "hills", displaying slow parts of frequency and small "hills", displaying fast parts of frequency. In the frequency range of less than 20-30 Hz, everything is represented.
For better evaluation of different parts of frequency in the EEG, a mathematic principle is used. The "Fourier-Trainsformation", from the mathematician Jean Baptiste Joseph Fourier, 1822). Parts of frequency are calculated and displayed through bars, as with our software:
The deflexion of the bars shows the amplitude of the corresponding frequency range. The digits on the bars represent the frequency in Hz. The boarder displays the amplitude in µV.
The frequency bands are represented by different colors. Pink for delta waves, purple for theta waves, green for alpha waves, yellow for lower beta waves, orange for mediocre beta waves and red for high beta waves.
We are able to see some peaks (frequency-edges) e.g. at 2,5 and 12 Hz. Peaks in the delta area are usually muscle-artefacts during wake-EEG and are therefore neglected. Theta, alpha and beta waves represent frequency ranges that are interesting for neurofeedback.
Training with Brain Waves
This control cycle describes the methods of neurofeedback with our MindMaster® EEG and the software MindStream such as Mindifeld BioEra..
What can we change now with the help of neurofeedback-training?
We can:
- train, heighten or lower the amplitude in a frequency or a frequency band.
- try to move amplitudes from specific frequency ranges to others.
- change the proportion of amplitudes in one frequency range to amplitudes in other frequency ranges.
As we can see, our focus lies predominantly on the amplitude and the things it influences the most. But what does a high amplitude of lets say 8-12 Hz mean? What this indicates is that millions of neurons communicate with each other synchronously at a rate of 8-12 Hz. Synchronously is the magic word here because only when the process happens synchronously, the potentials summ up and create an EEG with a high amplitude. In this case we train a synchrony of cerebral activity in the alpha-range. Many scientific studies prove, that an enhanced cognitive ability derives from this phenomenon. This fact is obvious when one imagines that all neurons pull together on one string and create an enhanced capability.
We can thus train and create synchrony, by giving a positive feedback, as soon as an elevation of amplitude is measured in the desired range. In some cases though, it is wise to neglect synchrony. You can find more information about that in the specific areas of application of neurofeedback.
Often, a disadvantageous proportion of the amplitudes in one frequency range to the amplitudes on other frequency ranges can be enhanced through training. For this purpose we use logical combinations in our software. A positive feedback can thereby only appear, if e.g. more beta waves AND at the same time less theta waves are fabricated. With "more" or "less" we indicate an elevated or a lowered amplitude.
The possibilities of influencing the amplitudes and their appearance in various frequency ranges are manifold. This section should have given you an impression of some of them.
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