Brain-computer interface

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A Brain-Computer-Interface ( BCI ), also Brain-Machine-Interface ( BMI ), German brain-computer-interface (sometimes also brain-machine-interface or computer-brain-interface ), is a special human-machine-interface without activation of the peripheral nervous system, e.g. B. the use of the extremities enables a connection between the brain and a computer . For this purpose, either the electrical activity is recorded (non-invasively mostly using EEG or invasively using implanted electrodes) or the hemodynamic activity of the brain is measured (using fMRI or NIRS ) and analyzed with the help of computers ( pattern recognition ) and converted into control signals. The BCI is an application of neurotechnology .


Scheme of a brain-computer interface

Brain-computer interfaces are based on the observation that the very idea of ​​behavior triggers measurable changes in electrical brain activity. For example, the idea of ​​moving a hand or foot leads to activation of the motor cortex . In a training process, the brain-computer interface (i.e. both the computer and the person) learns which changes in brain activity are correlated with certain ideas . This information can then be converted into control signals for various applications. An example of a simple brain-computer interface is a choice from two alternatives, in which the user imagines either moving the left hand or the right foot.

Communication between man and machine is only possible in one direction with all of the brain-computer interfaces developed to date. Humans learn to use their thoughts to communicate something to the computer, but the computer's response has so far only been conveyed via the normal sensory systems of the organism (e.g. images, sounds, or electrical irritation of the skin). In this way, the area of biofeedback / neurofeedback is used with the brain-computer interfaces .

Application examples

The most important application of brain-computer interfaces is to support physically disabled people. In conjunction with a spelling machine, they can enable people with a locked-in syndrome who cannot move the muscles they need to speak to communicate with the outside world.

Brain-computer interfaces should also serve to increase the mobility of the disabled. The aim here are prostheses or neuroprostheses controlled by nerve impulses , which come ever closer to real limbs.

The number of commands that a brain-computer interface can reliably differentiate depends largely on the quality of the EEG. In principle, measurements on the scalp have only a very limited accuracy. The development of electrodes that can remain implanted in the long term is therefore a current research topic.


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