Understanding neurotherapy

Overview

Three ways neurotherapy works

Select an area to see how it works.

Feedback training

How feedback training works

When people can see or hear what their brain or body is doing, they can learn to change it. The brain learns from feedback much as it learns any skill, through repetition and reward. The aim is for the new pattern to become easier to produce on its own.

Types of feedback training

Feedback training

Amplitude neurofeedback

Also called traditional or frequency-band training

EEG activity contains rhythms at different speeds, grouped into frequency bands from slow delta to fast beta. In amplitude training, the practitioner chooses one or more scalp sites and sets targets: increase (reward) activity in some bands and reduce (inhibit) activity in others.

When the brain moves toward the target, the feedback responds, for example a video brightens or a game moves forward. Sites and targets are usually chosen with the help of an assessment such as a QEEG.

Feedback training

Infra-low frequency (ILF) neurofeedback

Training the brain's slowest rhythms

Beneath the familiar EEG rhythms are very slow fluctuations, below 0.1 Hz, that rise and fall over tens of seconds to minutes. These slow rhythms are thought to relate to the brain's overall level of arousal and the coordination of its large-scale networks.

In ILF training the feedback changes continuously as this slow signal moves, rather than switching on when a threshold is crossed. The practitioner adjusts the training frequency from session to session, guided by how the person feels and responds.

Feedback training

Heart rate variability (HRV) biofeedback

Training the rhythm between breath and heartbeat

A healthy heart does not beat like a metronome. Heart rate naturally rises a little as you breathe in and falls as you breathe out. The size of this variation reflects how flexibly the nervous system can shift between activation and rest.

HRV biofeedback shows heart rhythm on screen and guides slow, paced breathing, often around six breaths a minute. At this pace the breathing and heart rhythms line up and the variation is at its largest, which is thought to strengthen the reflexes that help regulate blood pressure and the stress response.

Feedback training

Biofeedback and HEG

Biofeedback uses sensors on the body to show signals people are usually unaware of, so they can learn to influence them.

Hemoencephalography (HEG)

HEG trains blood flow and oxygenation in the front of the brain, the prefrontal cortex, which is involved in focus, planning and self-control.

nIR HEG shines red and near-infrared light into the forehead and measures how much returns. Oxygen-rich and oxygen-poor blood absorb these wavelengths differently, so the ratio reflects local oxygenation. pIR HEG instead measures the heat given off at the forehead, which reflects metabolic activity beneath.

Neuromodulation

What is neuromodulation?

Neuromodulation changes the activity of nerves by delivering a signal to a target in the nervous system. Unlike feedback training, the person does not need to learn anything for the signal to act, although the two are often combined.

The signal can be chemical, electrical, magnetic or light. Its effect depends on the type of signal, its strength and timing, and where it is applied.

Neuromodulation

Electrical stimulation

Most electrical approaches used in neurotherapy pass a very weak current through the scalp or skin. They are subthreshold: they make neurons slightly more or less ready to fire, rather than firing them directly. What differs between them is the shape of the current over time.

Neuromodulation

Magnetic stimulation

A changing magnetic field passes through the scalp and skull without resistance and induces small electrical currents in the tissue beneath, a principle called electromagnetic induction. The strength, focus and timing of the field decide what it does.

Neuromodulation

Light: photobiomodulation

Also called low-level light therapy (LLLT)

Photobiomodulation (PBM) uses red and near-infrared (nIR) light at levels too low to heat or damage tissue. The light is absorbed inside cells, mainly by an enzyme in the mitochondria, the cell's energy producers, and this sets off a chain of biological changes.

Common wavelength ranges

LEDs and lasers

Both deliver light at the wavelengths used in PBM. What matters most is the dose that reaches the tissue, not the device type.

Near-infrared is not heat

Near-infrared light, roughly 700 to 1100 nm, is invisible and works through absorption in cells rather than by warming tissue. Far-infrared heat lamps and saunas act mainly through heat, which is a different mechanism. With PBM, wavelength, power, time and area all shape the effect, and more light is not always better.

Assessment

Assessment in neurotherapy

Practitioners use different assessments depending on their professional background, training and the approaches they offer. Assessment helps set a starting point, guide the choice of approach and settings, and measure progress over time.

No single test diagnoses a condition on its own. Results are interpreted alongside your history, goals and other information.

Assessment

QEEG and ERP

QEEG: quantitative EEG, or brain mapping

EEG is recorded from 19 or more standard sites across the scalp, usually with eyes closed, eyes open and sometimes during a task. A QEEG is much more than a set of coloured maps. Its value lies in understanding the brain's rhythms: what they are, where they appear and how they behave.

Reading the rhythms. A trained clinician reads the raw EEG first: the frequency, shape, size and location of each rhythm, and how it reacts. For example, alpha should strengthen at the back of the head when the eyes close and settle when they open. Slow activity where it would not be expected, rhythms that do not react, or differences between the two sides of the head can all be informative.

Cleaning the recording with ICA. EEG picks up more than brain activity. Independent component analysis (ICA) separates the recording into independent sources, so that eye blinks and movements, muscle tension and heartbeat can be identified and removed while the brain activity is kept. Components can also be examined in their own right to understand the likely brain sources and networks behind the rhythms.

Measuring and comparing. The cleaned EEG is then quantified: the power in each frequency band, the peak alpha frequency, the balance between rhythms and how regions communicate (connectivity). Source localisation, such as LORETA, estimates where in the brain the activity arises. These measures are compared with a database of people of a similar age.

How it guides a plan: maps help the practitioner decide where to place sensors or electrodes, which frequencies to train or stimulate, and which approach may suit. A later map can be compared with the first.

ERP: event-related potentials

An ERP is the brain's electrical response to a specific event, such as a tone or picture. It is recorded while the person does a simple task, such as a GO/NOGO task (respond to some images and hold back for others) or an oddball task, where a rare target sound or image appears among frequent standard ones.

A single response is tiny and hidden within the ongoing EEG, so many responses are averaged. The result is a waveform whose peaks reflect the stages of processing the event.

Timing and size. Latency, how long after the stimulus a peak appears, reflects processing speed. Amplitude, the size of the peak, reflects the resources the brain commits. Both are compared with age-matched norms. ICA can also be applied to ERPs to separate overlapping components and link them to their likely brain sources.

How it guides a plan: ERPs add information about attention, response control and processing speed that a resting QEEG cannot show. This can refine a plan, and repeating the test shows change over time.

Assessment

Other assessments

Alongside or instead of a full QEEG, practitioners may use shorter or different measures, chosen to suit the person and the approach.

Measuring progress

These measures are most useful when repeated. Comparing results with the starting point shows whether things are changing and helps the practitioner adjust the plan, rather than relying on impressions alone.