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Monday, 9 April 2012

Brain Computer Interfacing

As the power of modern computers grows alongside our understanding of the human brain, we move ever closer to making some pretty spectacular science fiction into reality. Imagine transmitting signals directly to someone's brain that would allow them to see, hear or feel specific sensory inputs. Consider the potential to manipulate computers or machinery with nothing more than a thought.Brain computer interface uses the direct communication between the brain and computer. Brain computer interfacing is mainly used for catching the brain signals. The captured signals are translated into commands and this allows to control some devices like robots, computers etc. Human brain contains large number of neurons and is connected to another by axons and dendrites. Brain computing is done by small electric signals that take from neuron to neuron as fast as 250 mph. Mylin is used to insulate the path of the signals and some electric signals escapes. Such signals are taken by the scientists. The Electrodes read signal from the head surface. After that the signals are amplified. The converter changes signals from analog to digital form. Computer is used to process the data.

For getting the higher resolution signals the scientists implement electrodes directly into the gray matter of the human brain. Also we can set it on the surface of the brain beneath the skull. This technique helps to get direct reception of electric signals and also allows placing electrode in a specific area in the brain. But this technique has many problems. This requires surgery and it also a cause for the formation of scar tissue. The scar tissue does not allow the flow of signals or it blocks the signals. Neurons voltage difference is measured by the electrodes. After that the signal is amplified. The next step is filtering of the amplified signal. Cochlear implant is the most common and the oldest way for using BCI. In average person the sound waves will enter through the ear and it passes through many small organs. It passes the vibrations into the auditory nerves as an electric signal. If the person loosed his hearing ability then he can’t hear anything.

Different types of electrodes are used for brain computing. The main types are needle electrodes, disposable (gel-less and pre-gelled types), headbands and electrode caps, reusable disc electrodes (gold, silver, stainless steel or tin), saline-based electrodes. The amplifier used for it should not influenced by the physiological process. Measured signal do not distorted. The amplifier must have good interferences and separation of signals. And also it must protect the patient from any type electric shock. It can resist against the high input voltages.


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