BRAIN COMPUTER INTERFACE

BRAIN COMPUTER INTERFACE

INTRODUCTION:

Brain Computer Interfaces (BCI) are systems, which use human thought as a communication channel between Brain and Computer. The BCI system does not depend on the brain’s normal pathways of peripheral nerves and muscles rather transforms specific ‘thoughts’, which is a synonym for these specific states, into control signals. These are then converted into computer readable form so that they can be fed to the computer. This computer now will interpret the instructions it receives from the brain. These instructions are nothing but our thoughts.

The immediate requirement of a BCI system to work is to acquire the signals generated by the brain. It is believed that the brain radiates certain electromagnetic signal during thought process. When a person thinks about performing a particular task such as raising a finger, this gives rise to brain activity that can be measured through the scalp via electronic sensors called Electrodes. A BCI relies specifically on the analysis of brain signals created by the different mental tasks. Measured signals do, however, contain background Noise. The challenge is to identify those particular signal characteristics that relate to those particular mental tasks.

The brain’s electrical activity can be measured and monitored by a variety of non-invasive and efficient ways. The non-invasive methods now available include Electroencephalography (EEG), Magneto Encephalography (MEG), Positron Emission Tomography (PET), and Functional Magnetic Resonance Imaging (FMRI). PET, MEG and FMRI are expensive and complex to operate and therefore not practical in most applications. At present, only EEG, which is easily recorded and processed with inexpensive equipment, appears to offer the practical possibility of non-invasive communication channel. Further more, EEG signals are rather well studied and there is evidence that subject can control them to some extent in a voluntary manner.

Assessment and interpretation of the Brainwaves, recorded as Electroencephalograph, is a crucial process in a BCI system. The EEG signals recorded are needed to be analyzed and converted to the computer readable form so that the computer can analyze and perform the required task represented by the signal it receives. This involves the EEG signal processing to extract and present the frequency and amplitude information .Different methods of signal processing are used to interpret these signals which include Multi-variety Autoregressive Analysis, Fourier Transformation and Fast Fourier Transformation of the signals.


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