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Brain-Computer Interfaces and NeuroProsthetics: an Introduction

Posted: Fri, February 06, 2015 | By: Misc

by Alexander Borch Kristensen

The first time I was introduced to the term ‘Brain-Computer Interface’ was in the book by Zack Lynch, ‘The Neuro Revolution’. The book introduces the reader to a broad spectrum of neuro-disciplines, but the words Brain-Computer Interface and Neuroprostheses popped up in my face repeatedly and out-shined all the other interesting content of the book. I decided to research the topic and subsequently I wrote this (hopefully easy-to-understand) introduction to the area of Neuroprosthetics and BCIs.

Brain Computer Interface (BCI) aka, Brain Machine Interface(BMI)/Mind Machine Interface(MMI)/Direct Neuronal Interface(DNI)/Synthetic Telepathy Interface(STI)

Imagine the ability to control a computer without using any muscles. Just by tracking the electrical currents in your brain you could move the cursor around as you wished. This discipline of interaction between a brain and a computer has developed into various branches of research which I personally find very interesting.

As a neuron processes information an electrical potential travels along the axon of the neuron. The neuron is active and fires. By monitoring how active different areas or even specific neurons are, it’s possible to figure out the intentions of the brain (for example move the computer cursor slightly to the left.) This might be an oversimplification, but you get the point.

Non-invasive BCIs

For a long it has been possible to measure electrical activity in the brain, using EEG. It has almost become an art for companies, like NeuroSky, to create software or apparatus that can be controlled by the EEG signals monitored. By wearing nothing more than a headset computer games can be played and toys can be played with just by using your mind!

Some applications for a MindWave mobile, the headband monitoring brain waves, are explained in this video:

Patients that are in a locked-in state or are paralyzed, and therefore aren’t able to use any of their muscles or speak, but still possesses a full functioning brain, can benefit from the P300 Speller.

The P300 speller principle is based on Event Related Potential (ERP.) A computer displays a 6x6 matrix of letters and figures. Then the various columns and lines light up in a random order. As the letter or figure the patient wishes to type lights up - action potential is released in the brain and registered using EEG. As the letter lights up multiple times releasing potentials more than once, the computer is able to figure out which letter the patient wishes to spell out using algorithms. The subject is thereby able to spell out words and sentences. [1]

The BCI applications with the EEG technique are limited as each electrode detects action potential from many neurons. At the same time a lot of the signals are diffusely scattered before it reaches the other side of the cranium and the scalp.

Issues like that aren’t a problem in Invasive BCIs.

Using surgical intervention researchers are able to monitor the potential of a single neuron. By using algorithms, a computer is able to decode different patterns of activation and can thereby guess which physical action the subject wishes to perform. Translating this into physical movement a prosthetic arm can be moved as the subject wishes. Results were revealed in May 2008 when the University of Pittsburg Medical Center showed a Rhesus Monkey feeding itself with marshmallows using a prosthetic arm.

Follow this link to see it for yourself:

In 1978 a man known by the name “Jerry” who had been blinded in adulthood had electrodes implanted in his visual cortex which allowed him the sensation of seeing phosphenes or light. The system consisted of a digital camera applied to his sunglasses which connected to the electrodes through a computer. [2] The system is illustrated at the image on the left.

Johnny Ray was the first patient who gained control of a computer using his brain. In 1997 he suffered from a brain stem stroke sending him into a ‘locked-in state’. In 1998 a surgical intervention helped him gain control of a computer giving him the ability to write words and generate musical tones. [3]

Another historical point in BCIs was made as Matthew Nagle was enabled not only to control a computer but also - as the first patient in the world - to grab and move around with a prosthetic hand. Nagle was injured in an accident in 2001 and became paralyzed from the neck down. He volunteered three years after the accident to have an array of electrodes implanted into his primary motor cortex. [4]

Invasive BCIs have great potential for the future. However, surgical intervention provokes ethical questions in some people. Other problems are preventing the body from rejecting the implanted electrodes (since it’s a foreign object) and preventing electrodes from scarring the brain tissue, in the long run.

Semi invasive

By placing plastic coated electrodes under the skull on the surface of the cortex the body’s doesn’t reject them like invasive BCIs and signals recovered are much clearer than in EEGs. This method is called Electrocorticography (or ECoG) and has enabled a teenage boy to play Space Invaders just by using his mind. ECoGs are implanted temporarily for the medical purpose of tracking epileptic seizures in a patient. BCI functions (for example playing Space Invaders) can be applied afterwards. This of course leads to a limited source of test subjects. [5]

Hippocampal prostheses

Another term in the book by Zack Lynch that hasn’t been mentioned as a BCI but I believe fits in that category is Neuroprosthetics.

Theodore Berger - biomedical engineer and neuroscientist at the University of Southern California in Los Angeles - and his colleagues succeeded in creating a prototype of hippocampus prosthesis. Depending on which kind of memory is supposed to be encoded in the brain a series of electrical pulses are fired from the hippocampus. The pattern of the pulses represents a specific memory being encoded. It’s as simple as that. [6]

An electrode in the hippocampus of a rat captured the electrical pattern as the rat learned the simple task of pulling a specific lever for a reward. The rat was then given a drug that made it forget the lesson which it just had learned. By simulating the same pattern of electrical sequences with an electrode the same rat once again was taught how to choose the right lever. [7]

The same test was next applied to primates. The pattern was captured as monkeys were shown an image. The memory of the image, consolidated in the prefrontal cortex, was interrupted by drugging the monkey with cocaine. After simulating the same pattern again with an electrode, the monkeys scored much higher on image identification tasks. [8]

An article published last year stated that Berger and his colleagues hope to implant the first hippocampal prosthesis in an animal within a two year horizon. The implant would be in the form of a chip that should be able to replace functions of the hippocampus and possibly form long-term potentiation. [6]

Zack Lynch states that progress in this technology is very interesting for the military. The idea of having an artificial hippocampus that can be applied to a subject by implant or externally be worn means that the subject would be able to learn new languages instantly or memorize particular faces of relevance. [9]

BCIs are very interesting to transhumanists, because they could expand longevity by replacing vital brain parts that decompose with age.

If this topic catches your interest, I recommend reading further into it.


  9. ‘The Neuro Revolution’ – Zach Lynch

Image references:


Alexander Borch Kristensen is 20 years old. He studies biotechnology at the Danish gymnasium of Grindsted, where he graduated in the summer of 2014. He’s a brain enthusiast and always eager to learn more about the brain. He’s currently taking the ‘Certificate in Brain Health and Social Policy’ course at Brighter Brains Institute.


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