Brainwaves and Neurofeedback: How Brain State Training Works

Life depends on nerve cells firing. Each time neurons pass electrochemical signals to one another, that activity throws off a faint electromagnetic field, small but real enough to measure (Libenson, 2010). The instrument that picks it up is the electroencephalograph, or EEG. What it records is the rhythm of neural firing, the thing people call brainwave activity, and those rhythms sort into bands: delta, theta, alpha, beta, gamma. Pair an EEG with a computer that feeds the readings back in real time, and a person can start to learn which brain regions they are turning up or turning down, and how to steer that on purpose toward useful ends.

Paul Swingle lays out the human range a little differently, adding Sensory Motor Rhythm (SMR) between alpha and beta (Swingle, 2008). Every band maps to a corresponding mental state. Some of those states are the signature of a balanced brain; others show up when something is off. You can have too much of a given rhythm or too little, and either extreme has been tied to particular neurological pictures. Depression, traumatic brain injury, ADD, autism, anxiety: all of these have been associated with specific brainwave signatures, which is the logic behind using technology to nudge imbalanced patterns back into range.

Delta sits at the bottom. It oscillates somewhere around 0.5 to 2 Hz, the slowest frequency the brain produces. When delta dominates as you grow drowsy or sink into the deeper reaches of sleep, that is exactly where it belongs. The problem is delta showing up while you are supposed to be awake and sharp. Too much of it over the frontal area during waking hours can feel like mental fog or plain exhaustion, and frontal delta excess has also been connected to chronic pain conditions such as fibromyalgia.

Theta is the next step up, oscillating between roughly 3 and 7 Hz. Experienced meditators learn to generate strong theta on demand, and the state it accompanies is the one associated with hypnotic trance, inward attention, contemplation, a quiet mind, and thinking about one's own thinking. It does a lot of the work of settling the nervous system and loosening the grip of attention. Swingle notes that a shortage of theta at the occipital region tracks with anxiety, 'sleep disturbance, low stress tolerance, and a predisposition to addiction' (Swingle, 2008 p. 45). Damaged brain tissue runs into a related trap: often it cannot push its amplitude any higher than theta, which hampers its ability to talk to the tissue around it and can produce the same cluster of symptoms.

Alpha runs higher, from about 8 to 12 Hz, and it is usually there while you are awake. Think relaxed alertness. Clinicians read alpha to gauge how much room a patient has to grow their cognitive flexibility. The ratio inside the band matters too: when the faster slice (10 to 12 Hz) outweighs the slower slice (8 to 10 Hz), a person tends toward higher intelligence and quicker processing than someone with the reverse balance. Alpha also has a pathological face. In 'Alpha Wave Intrusion,' the brain substitutes alpha for the delta it needs during sleep, and this has been linked to chronic pain disorders including fibromyalgia (Germanowicz, Lumertz, Martinez, & Margarites, 2006).

SMR occupies a thin strip between 13 and 15 Hz, sometimes described as part high alpha, part low beta. Healthy SMR shows up as physical presence, calm, and steady attention. When it goes wrong, the associations turn to depression, seizures of various kinds, chronic pain, tremors, and dystonia.

Beta, from roughly 16 to 25 Hz, climbs when the mind gets busy, and it climbs most of all during arithmetic and problem solving. Trouble comes in two forms. One is a brain that cannot raise and lower its beta smoothly. The other is simply too much beta, a pattern that goes along with emotional volatility, anxiety, and chronic fatigue.

Above beta sits gamma, between about 28 and 40 Hz. In a healthy brain gamma means focus, the stitching together of separate regions, fast processing, and real engagement with a task, which is why it gets targeted when memory or attention begins to slip. The unhealthy version tracks with Obsessive Compulsive Disorder, poor memory, and an overactive cingulate gyrus. Autistic children frequently show the troubled gamma pattern, so neurofeedback is applied to quiet that overactive cingulate gyrus. Once you hold a rough map of the bands and the subjective states that ride along with them, the clinical reports start to make sense.

Neurofeedback is one branch of biofeedback, aimed at the neurological side of mental disorders. Biofeedback as a whole just means handing an organism information about its own physiology (heart rate, blood pressure, and so on) in a form that makes those processes easier to influence on purpose. EEG-biofeedback narrows that to brainwaves: an EEG detects a pattern, the pattern gets reflected back to the person, and with practice the person gains more say over it. Since psychological illness so often carries a neurological component, interest in neurofeedback as a treatment has kept growing. From 1958 onward it has been put to clinical use across the back half of the twentieth century and into the twenty-first, applied to serious disorders.

'A Symphony in the Brain' traces the clinical reach of today's methods back to the experimenters of the nineteenth and early twentieth centuries (Robbins, 2008). In the 1870s Richard Caton became the first English physician to record brainwaves, wiring a reflecting galvanometer to the exposed brains of rabbits and monkeys. The device was crude but it caught shifts in the electrical current of living brain tissue, and in time it registered signals through the skull itself.

Then came 1924, when the German psychologist Hans Berger pulled brainwave frequencies through the scalp of a living person for the first time. He got there after a run of experiments on patients missing sections of bone, using electrically sensitive nodes placed against the inner skull. That groundwork let him publish 'On the Electroencephalogram of Man,' where he tagged 10 Hz the 'Berger rhythm.' Other frequencies followed, and he was also the first to watch electrical brain death, in a dying dog. His work stayed mostly self-contained until Joe Kamiya ran the first neurofeedback experiment on American soil (Robbins, 2008).

Kamiya, a psychologist at the University of Chicago, set up that 1958 study, the first in which a subject actually shifted his own brainwaves. The design was single-subject, repeated measures. His subject, Richard Bach, was asked to say whether he was in a dominant alpha state each time a tone sounded. From a separate room Kamiya watched Bach's EEG trace and told him after each guess whether he had called it right. The opening trial ran in a single day: 60 tones, 60 yes-or-no answers about whether this was an alpha state. By the end of that first round, the results showed Bach could not yet tell the states apart.