A brain computer interface(BCI) is a system which translates the brain's electrical signals into outputs which then control a computer device, thereby creating a communication pathway between the brain and the computer. BCI's are mainly used when dealing with people who suffer from neurological neuromuscular disorders  to help them control these muscles by assisting, augmenting or repairimg the human cognitive, therefore enabling them to interact with the world.
How Do BCI's Work?
'BCI's measure brain activity, process it, and produce control signals that reflect the users intent' Brain-Computer Interfaces Revolutionizing Human-Computer Interaction  The brain is made up of millions of neurons which work constantly inside the brain every time we think, remember, move or feel. They work by sending electronic signals throughout the body through the nervous system in order to make the receiving nerve cells work. However, some of these electronic signals are lost in the process and these are the signals that scientists use to carry out the work of BCIs.
The easiest and most common method of using BCI is to attach an electroencephalograph (EEG) to the scalp of the subject. As the skull blocks most of the electronic signals, scientists now implant electrodes directly into the brain, beneath the skull, through invasive surgery in order to implant the electrodes. This eventually causes scar tissue which then in turn blocks the signals, creating an overall problem with the BCI. The electrodes measure changes in voltage in the neurons in the brain and then amplify and alter the signal.
BCI's may also be used through an MRI to measure brain activity. MRI machines aren't very suitable to BCI studies as they are big and bulky and although they produce an image of the brain, they can't be used as part of a permanent or semi-permanent BCI. Instead, MRI scans are used by researchers to plan where to place the electrodes or to identify which part of the brain is active when a subject thinks about doing a certain thing, this helps the researcher know what to do and where to go during the electrode implantation surgery.
The overall concept of BCI's is that a person can control an external device through only the use of their thoughts. The first-ever demonstration of bidirectional interaction was between BTI's and monkeys, which were used to research how effective this invention would ultimately be when connected to the brain. Firstly the scientists got the monkeys to control a robotic arm using a joystick, then again with electrodes implanted in their brains, the monkeys attempted to move the robotic arm using the signals from the electrodes. This was successful and showed the dynamics by which the BCI works, in one of it's simplest forms.
Virtual Reality and Videogames
BCIs can create a new way to play video games and interact with virtual worlds.  The brain can be connected to the computer and control virtual objects and change viewpoints, so basically, your brain would become your video game controller. But, this could make the game seem pointless to the user, so, BCI technology will never take over for the typical gaming controllers. Within the game, BCIs allow players to detect and monitor brain wave patterns such as a persons emotional state and stress level.
This technology has two different versions, implanted (such as, an earpiece) and unimplanted. Several BCI device producers strive towards operating a computer by thought alone. Companies like Emotiv Systems and Neuro Sky have released BCI software development kits.
A negative impact of BCIs being used in videogames and virtual realities are that users brains might be subject to negative, adverse effects this might cause users to slow down their brain waves leaving them unfocused and unable to carry out basic every day duties. The positive effects are that people with missing limbs can also participate in virtual tours, video games and virtual worlds.
BCIs being used in the majority of video games and virtual reality environments will be a major breakthrough in years to come.
Invasive Brain-Computer Interfaces (BCIs) are used primarily in Health Care targeted at repairing damaged sight and providing new functionality for people with paralysis.
BCIs focusing on motor neuroprosthetics aim to either restore movement in individuals with paralysis or provide devices to assist them, such as interfaces with computers or robot arms. Tetraplegic Matt Nagle became the first person to control an artificial hand using a BCI in 2005 as part of the first nine-month human trial of Cyberkinetics’s BrainGate chip-implant.Implanted was a 96-electrode BrainGate implant allowed Nagle to control a robotic arm by thinking about moving his hand as well as a computer cursor, lights and TV.
Studies also show that patients with access to brain computer interface technology recover more quickly from serious mental traumas, especially if there is underlying physical trauma that renders the patient incapable of communicating. By interfacing with a computer through a direct neutral connection, patients report a higher rate of mental engagement and ultimately , recovery Brain computer interface technology shows promising signs in both preventing and delaying the onset of dementia , Alzheimer's and Parkinson's disease in the elderly.
"Innovative technologies such as the brain computer interface may now allow better diagnosis in coma patients of whether consciousnesses is still exisent and how pronounced it is, and for the first time also enable communication with those effected" says Prof. Gustave Moonan ( Belgium ) at the annual conference of European Neurological society in Berlin.
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