Brain-computer interface

Also called BCI, Brain-machine interface, BMI, Neural interface

Selecting with brain signals, through a cap of electrodes or an implant. Real, slow, and mostly still in the lab; what it is and what it is not yet.

What it is

A brain-computer interface reads electrical activity from the brain and turns it into a selection, without any movement at all. The non-invasive kind uses a cap of scalp electrodes (EEG). The invasive kind uses electrodes implanted on or in the brain, which give a much cleaner signal at the cost of surgery.

It is the access method for when every other one has gone, and it is the one most misreported. Newspaper headlines describe people "speaking with their thoughts". What exists today is more modest, and worth describing honestly.

Who it can help

In principle, people with no reliable voluntary movement, including the eyes: complete locked-in syndrome, late-stage motor neurone disease, some brainstem stroke. In practice, in the UK today, it helps a small number of people in research studies.

It is not for anyone who has a working switch site, an eye movement or a blink, because all of those are faster, cheaper and available now. And it is not a way to read thoughts: every current system needs the person to do something deliberate, whether that is attending to a flashing letter or imagining a movement, and it needs training on both sides.

How it works

EEG spellers work by attention. Letters flash in a grid; when the letter the person is watching flashes, the brain produces a recognisable response (the P300) about a third of a second later, and after several repeats the software picks the letter. Rates are a few letters a minute. Other EEG systems read the rhythm changes when a person imagines moving a hand, giving a slow one- or two-choice switch.

Implanted systems, still in trials, decode attempted handwriting or attempted speech from the motor cortex and have reached tens of words a minute for a few participants. They need neurosurgery, a research team, daily recalibration and a device tethered to a computer. None is a product you can be prescribed in the UK.

Getting started

This week, the useful action is to make sure the person's existing access is being kept ahead of their condition, so that a BCI never becomes the only option. Ask the AAC service to plan the next switch site or an eye gaze trial now, and set up partner-assisted scanning as the floor.

If the person wants to take part in research, ask their neurologist or the MND Association about UK studies; participation is real and valued, and it should be described as research, not as treatment.

Where to get help

The specialised AAC services will know the current state of BCI and what is and is not available; ask at your AAC assessment. The MND Association signposts research studies, and Communication Matters includes BCI in its conference programme most years.