J. Biomedical Science and Engineering, 2008, 1, 170-172 Brain initiated interaction Rajesh Singla1& Dr Balraj Gupta 1 Department of Instrumentation and Control Engineering, Dr BR Ambedkar National Institute of Technology, Jalandhar-144011, India. Correspondence should be addressed to Rajesh Singla ([email protected]). Received March 4, 2008; revised September 5, 2008; accepted September 5, 2008 ABSTRACT ling the motion of the bed of severely paralyzed patients for drug and food delivery etc with the help of a stepper Brain-Computer Interfaces (BCI) are developed motor installed for controlling the motion of the bed in to help locked-in patients, who lose control of both directions i.e. up and down. their bodies and are unable to perform simple tasks such as speech, locomotion, and can’t 2. SYSTEM ARCHITECTURE even effectively interact, with their environment. Figure 1 shows the complete experimental setup of a BCI shows promise in allowing these individuals BCI system, designed to control environment (in this to interact with a computer using EEG. A Brain case motion of the bed). Computer Interface is a communication system The system is developed using virtual instrumentation in which messages or commands that an indi- SciRes Copyright © 2008 technology and consists of basic two modules: hardware vidual sends to the external world do not pass and software. The hardware set up of the system consists through the brain’s normal output pathways of of peripheral nerves and muscles. A system is created to allow individuals with motor disabili- • EEG equipment (Head box and adaptor box) ties to control the motion of the bed on which • Desktop PC interfaced to EEG Hardware via USB they are bedridden via BCI for drug delivery and port. other activities, with the help of eye motion and • USB based digital output signal interfacing board changes in the absolute power in alpha rhythms (National Instruments 6015) for motion control. of an EEG signal of the patient. Keywords: BCI, eye events, EEG, Lab VIEW 1. INTRODUCTION BCI (Brain Computer Interface) research is a multidisci- plinary field requiring the knowledge of neuroscience, physiology, psychology and engineering. For the devel- opment of BCI, we generally use the Electroencephalo- gram (EEG). EEG signal is composed of electrical rhythms and transient discharges. Features like wave shape, amplitude, frequency and power are detected Figure 1. Complete Experimental setup of a BCI system. which are typical for a particular act and it can vary from person to person. Once these features are detected, they can be used to generate a control signal by using Trans- lation algorithm and can be used to operate some devices. Brain-Computer Interface (BCI) shows a great potential to provide new channels for physically disabled people, especially locked in patients, to communicate and inter- act with the outside environment. EEG-based BCI is non-invasive, so it is more readily accepted. In this paper, we introduce the design of a BCI based on changes in EEG amplitude due to eye activity and in the absolute power of alpha rhythms after eye activity, followed by applications based on this core technology i.e. control- Figure 2. International system of electrode placement. Published Online November 2008 in SciRes. http://www.srpublishing.org/journal/jbise JBiSE  R. Singla et al/ J. Biomedical Science and Engineering 1 (2008) 170-172 171 The software module was developed program for BCI For easy understanding and debugging, the software using LABVIEW to perform the function of EEG acqui- code is divided into three sub modules namely: sition analysis and display. • EEG signal acquisition and processing module • Feature extraction module. 2.1. EEG Equipment • Device control module The device used for study is RMS 32 Brain View Plus. It EEG signal acquisition and processing module ac- can record 32 channels of EEG data from electrodes quires online EEG signal from EEG machine channel placed according to the international 10-20 system. The (FP2-F4), (FP1-F3) the channel being more sensitive to voltage generated by the brain cells and picked up by eye events. Also the signal is acquired from (O2-CAR), EEG is extremely small (between 10-20 microvolt) and CAR being the Common Averaged Reference, the chan- amplification is needed of the order of ten thousand nel most sensitive for variations in power of alpha times for successful recording of the EEG signal. The rhythms. The raw sampled EEG data file created by EEG odd numbered electrodes are placed on the left side of machine Super Spec software at the sampling rate of 256 the head while even numbered electrodes are placed on Hz is then read continuously at the start of acquisition. the right side of the scalp. The view of the electrode po- The raw data is then processed using as series of filters. sitions as seen from the side and top is as shown in the The signal is fed to a band pass filter implemented using following figure. low pass filter (4th order FIR filter with cut off 99Hz) and The standard parts of the EEG hardware include adap- high pass filter (4th order FIR filter with cut off 0.1Hz) to tor box, head box, connecting cable and PC. The Head limit the EEG signal bandwidth (0.1 to 99 Hz). A 50 Hz Box is used for connecting electrodes from the scalp to notch filter is used to remove power line interference. the hardware unit. The signal generated is amplified and The processed EEG data is fed to feature extraction then sent to adaptor Box for signal conditioning. The module which executes an amplitude and digital signal generated then, passes to the PC where it is time-duration-based algorithm to detect the changes in displayed on the screen on Super Spec software designed the EEG signal due to eye events such as eye open and for display of EEG Signals. eye close. Once the event of eye open and eye close is detected the systems then checks the absolute power in 2.2. Software Design of BCI the signal of (O2-CAR) channel in the frequency range Software for the Brain computer interface is designed on of 8 to 12 Hz of 512 samples with the help of FFT. If the the Lab VIEW platform which consists of software front event eye open is detected and then the power in the fre- panel for user interaction and block diagram program- quency range of 8 to 12 Hz is less than 0.5 V2 the device ming code to control the overall functionality of the sys- control module is executed to send a high Boolean data tem. Figure 3 shows the functional elements of BCI sys- type signal to a switch connected to digital output line tem. P03 of USB based interfacing board through DAQ assis- tant that moves the stepper motor in anti clockwise di- rection for 33 steps. Similarly If the event eye close is EEG EEG Data Acquisition & detected and the power in the frequency range of 8 to 12 Head Adaptor processing sub module Hz is more than 2.5 V2 of 512 samples the device control Box Box module is executed to send a low Boolean data type sig- Software module nal to a switch connected to digital output line P03 of USB based interfacing board through DAQ assistant that moves the stepper motor in clockwise direction for 33 Feature Extraction sub module steps. If the condition for particular event is not met the DAQ assistant is configured to send simultaneously the PC low Boolean data type signal at the particular output Screen Device control sub digital lines to make the bed remain in rest position. module Once the stepper motor has taken 33 steps for the bed Front panel motion no further action is taken for a time period of 5 User Interface Digital signals minutes what so ever may be the signal changes i.e. ACQ for BCI switch is made OFF. After 5 minutes Acquisition again starts and control action is taken accordingly. USB based Digital output interfacing board The overall software program functionality is con- User com- trolled by the customized design of soft front panel using connected to PC mands controls and indicators, on PC screen, through which the user interacts with the BCI system. It consists of ‘ACQ Signal to stepper motor via switch’ to start and stop the acquisition of EEG signal switch for motion control data file, ‘EEG recorder’ a calibrated waveform chart to show graphical record of EEG signal at the time of ac- Figure 3. Functional elements of a BCI system EEG hardware interfaced to PC quisition of (FP2-F4 and O2-CAR) and one virtual bed SciRes Copyright © 2008 JBiSE 172 R. Singla et al/ J. Biomedical Science and Engineering 1 (2008) 170-172 that can be moved up and down for 33 steps to depict the work best. If we increase the sensitivity the factor on status of the particular eye event and power in the alpha positive side now goes to 350 and on negative side it rhythms. goes to –225. Similarly we can further increase or de- crease the sensitivity factor depending on the patient’s 3. RESULTS context. Many factors determine the performance of a BCI sys- 4. CONCLUSION AND FUTURE SCOPE tem. These factors include the brain signals measured, the signal processing methods that extract signal features, The key is to take BCI technology beyond the demon- the algorithms that translate these features into device stration stage to the real world applications, so that the commands, the output devices that execute these com- quality of life for paralyzed patients is improved. We mands, the feedback provided to the user and the charac- detected the changes in the EEG patterns due to eye teristics of the user. The parameters of the features ex- events. We have used eye events and power in the alpha tracted vary from individual to individual so it is impor- rhythms for control of bed motion to facilitate the drug tant to develop the generalized BCI. The changes in the and food delivery to the patients. The possibility of ex- EEG due to eye motion are detected from the waveforms panding the BCI into latest technology will enhance the originating at FP2-F4, FP1-F3. The amount of change in adoption of this technology and develop into feasible the amplitude during eye open and eye close vary from solutions with further advances. It can be further used to subject to subject, location of electrodes on the forehead, design a virtual keyboard which can enable the locked in physiological state of the patient and contact impedance patients to interact with PC. of the electrodes on the scalp. The wave can be recon- structed and hence can be used for further control action in the development of BCI. The results are taken online. REFERENCES As soon as the BCI is switched on, the EEG pattern from [1] S. Gerwin, J.M. Dennis, H. Thilo, B. Niels and R.W. Jonathan the machine is recorded on the front panel and changes “BCI2000- A General purpose Brain Computer Interface(BCI) System” IEEE transactions on Biomedical Engineering, due to eye events are detected and displayed on the front Vol.51,No.6 , pp. 1034-1043. panel. 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