Neurofeedback is a form of biofeedback. In biofeedback, as the name suggests, precise instruments measure biological markers like brain waves(EEG), heart rate(ECG), breathing rate, skin conductance etc. and provide feedback to the user in real time about what is happening in their body. It is is an experiential learning technique, similar to learning to play an instrument which provides user the skill to self-regulate, gain greater control over their body. Neurofeedback just focuses on the changes in brain wave patterns and it provides feedback based them.
Until around the 1970s, neuroscientists believed that the brain’s structure and function was essentially fixed throughout adulthood. In last 5 decades, scientist have discovered the amazing ability of human mind to change and grow at any age . Neurofeedback is designed to take advantage of this ability.
The fundamental principle behind Neurofeedback is Operant Conditioning. Consider the story of the professor whose students trained him with operant conditioning. The professor had the habit pacing right to left while delivering his lecture. Each time he moved to right side of the room, the student paid rapt attention. Each time he moved to the left side of the room, they paid less attention. By the end of the lecture hour, his shoulder was pressed against the right wall. In this example the professor was unaware of the ruse and the pacing left to right was a natural event, but with reinforcement he received from the class and his desire for class’s attention had him engage in the process. Similar to professors’s natural state of pacing left and right, our brain waves fluctuate outside our conscious awareness. Reinforcing desired brain wave patterns in real time is Neurofeedback .
Now the question arises, what are desired brain wave patterns? Following table shows positive and negative implication associated different brain wave frequencies.
|Band||Frequency Range||Negative reflection||positive reflection|
|Delta (δ)||1 – 4 Hz||Brain Injury, Sleep deprivation||Sleep, abstract Mental processing|
|Theta (θ)||4 – 8 Hz||ADHD, Depression, poor judgement||Creativity|
|Alpha (α)||8 – 12 Hz||Mental fog, slow processing, insomnia||Internal reflection, brain synchrony, peak performance|
|Beta (β)||12 – 30 Hz||Anxiety, Insomnia, Migraine, OCD, perfectionism||Alertness, focus, peak performance|
|Gamma (γ)||35 – 80 Hz||Poor abstract thinking and memory consolidation||Higher mental processing peak performance|
Once we capture EEG, we need to make sure which region of the brain we need to train, for that we need to identify regions of the brain which are outside the “normal” range. To identify these regions, there has to be a baseline to compare to.
The following section is going to be a little mathematical, if you are not interested you can directly go to the next subsection.
To generate the baseline, EEG data is recorded from hundreds of participants in 3 to 80 years in age. Numerical analysis are done on this data to calculate mean and standard deviation for each age group, these databases are called normative databases. Normative because the data captured from people follows normal(gaussian) distribution. Don’t run away just yet, all it means is that we need the calculate z-score using the following formula to compare our EEG parameters to database.
where, x is the input parameter, μ is mean and σ is the standard variance from the database for that particular parameter. The following image represents a standard normal distribution, with x-axis representing z-score value and the y-axis representing probability of that value. One interesting thing to notice from the curve is as you go towards the either tail of the curve probability goes down. 95.4% of the entire population falls in between -2 and 2. Hence the neurofeedback providers are usually more interested in z-scores outside this range to train.
Assume, you are facing problem focusing on any thing and visit a neurofeedback practitioner. Most probably, the practitioner would use 19 channel EEG cap connected to their computer. Software in their computer will analyze your EEG data with expected activity and might report something like:
If you remember 10-20 placement system, then you can see areas marked in red(z-score > 2) are the ones which are higher as compared to the population average. This also explains, the problem you are having with focus. If you have a look at the table above negative implication of theta wave were ADHD, depression. Even though it is not enough for a diagnosis but it can explain trouble in focusing.
Over the following session, the practitioner will try to inhibit theta waves recommending some focusing exercises and as soon as you loose focus you will receive feedback via audio or visual, not letting you loose focus. Usually over 10-30 sessions this will train your brain how to control your focus yourself.
This was a brief introduction to Neurofeedback, if you wish to read more about the topic, please refer the books mentioned below. If you find this interesting do subscribe to our blog and leave your comments below if you want a particular topic covered for the future blog.
 Merzenich, M.M., 2013. Soft-wired: How the new science of brain plasticity can change your life. Parnassus.
 Demos, J.N., 2019. Getting Started with EEG Neurofeedback. WW Norton & Company.