Brain-Computer Interfaces

1. Brain-Computer Interfaces BCI

2. Brain computer interface • Basic Idea • Generic BCI system • Types of BCI system • EEG technique • Applications • Advantages • Disadvantages • BCI Innovators • Future developments BCI

3. MAN AND THE WORLD Man interacts with the world using his five senses and limb movements BCI

4. THOUGHTS faster than ACTIONS • Actions are mechanical movements while thoughts are electrical impulses. • Thoughts are faster than actions • So direct interaction with the world through thoughts would be faster. BCI

5. Brain Computer Interface • Brain-computer interface (BCI) is a fast-growing emergent technology in which researchers aim to build a direct channel between the human brain and the computer. BCI- The Ultimate in Human Computer Interfacing BCI

6. What is it good for? • Neurofeedback • treating attention deficit hyperactivity disorder (ADHD), poor concentration • Brain Computer Interfaces • People with little muscle control (i.e. not enough control for EMG or gaze tracking) • People with ALS, spinal injuries • High Precision • Low bandwidth (bit rate)

7. Components of BCI • Generation of • signals from brain • Preprocessing, • Feature extraction, • Classification, • Device control. BCI

8. Generic BCI System BCI

9. signal extraction techniques Different neuroimaging methods are used to derive meaningful interpretations from the brain signals which are captured by microelectrodes: • EEG - Electro encephalography • ECoG - Electro cortico graphy • MEG - Magneto encephalo graphy • BOLD - Blood-Oxygen-Level-Dependent (signal) • MRI - Magnetic Resonance Imaging BCI

10. What is an EEG? • An electroencephalogram is a measure of the brain's voltage fluctuations as detected from scalp electrodes. • It is an approximation of the cumulative electrical activity of neurons.

11. EEG Background • 1875 - Richard Caton discovered electrical properties of exposed cerebral hemispheres of rabbits and monkeys. • 1924 - German Psychiatrist Hans Berger discovered alpha waves in humans and invented the term “electroencephalogram” • 1950s - Walter Grey Walter developed “EEG topography” - mapping electrical activity of the brain.

12. Types of BCI Invasive- inside grey matter of brain Partially Invasive- inside the skull but outside the grey matter Non Invasive- outside the skull, on the scalp BCI

13. Invasive BCI S • Electrode inserted directly into grey matter • Highest quality signal can obtain • But are prone to scar-tissue build-up BCI

14. Partially Invasive BCIs • Implanted inside the skull but rest outside the grey matter of the brain • Produce better resolution signals than non-invasive BCIs where the bone tissue of the cranium deflects and deforms signals • Carry lower risk of forming scar-tissue in the brain than fully-invasive BCIs. BCI

15. Non-Invasive BCIs • low signal quality due to electrodes are not directly interact with neurons • It is safest as no surgery required. • EEG is widely used for this technique BCI

16. EEG Technique for BCI • Electrodes attached to the scalp • Electric signals of the brain are amplified. • Transmitted to the computer • Software converts them into technical control signals ( computer commands) • These computer commands controls the devices. BCI

17. Physical Mechanisms • EEGs require electrodes attached to the scalp with sticky gel • Require physical connection to the machine

18. Cerebral Cortex Parietal Lobe - involved in the reception and processing of sensory information from the body.Frontal Lobe - involved with decision-making, problem solving, and planning.Occipital Lobe - involved with vision.Temporal Lobe - involved with memory, emotion, hearing, and language.

19. EEG WAVES There are 5 major types of EEG waves • Delta Waves • Theta Waves • Alpha Waves • Beta Waves • Gamma Waves BCI

20. Continuous Brain Waves • Generally grouped by frequency: (amplitudes are about 100µV max) BCI

21. Electrode Placement • Standard “10-20 System” • Spaced apart 10-20% • Letter for region • F - Frontal Lobe • T - Temporal Lobe • C - Center • O - Occipital Lobe • Number for exact position • Odd numbers - left • Even numbers - right BCI

22. Electrode Placement • A more detailed view: BCI

23. Alpha and Beta Waves • Studied since 1920s • Found in Parietal and Frontal Cortex • Relaxed - Alpha has high amplitude • Excited - Beta has high amplitude • So, Relaxed -> Excited means Alpha -> Beta

24. Mu Waves • Studied since 1930s • Found in Motor Cortex • Amplitude suppressed by Physical Movements, or intent to move physically • (Wolpaw, et al 1991) trained subjects to control the mu rhythm by visualizing motor tasks to move a cursor up and down (1D)

25. Mu and Beta Waves • (Wolpaw and McFarland 2004) used a linear combination of Mu and Beta waves to control a 2D cursor. • Weights were learned from the users in real time. • Cursor moved every 50ms (20 Hz) • 92% “hit rate” in average 1.9 sec

26. BCI Examples - Prostheses • (Wolpaw and McFarland 2004) allowed a user to move a cursor around a 2 dimensional screen • (Millán, et al. 2004) allowed a user to move a robot around the room.

27. BCI Examples - Music • 1987 - Lusted and Knapp demonstrated an EEG controlling a music synthesizer in real time.

28. In Review… • Brain Computer Interfaces • Allow those with poor muscle control to communicate and control physical devices • High Precision (can be used reliably) • Requires somewhat invasive sensors • Requires extensive training (poor generalization) • Low bandwidth (today 24 bits/minute, or at most 5 characters/minute)

29. Area of implementation • Medical science • Enabling disabled people • Vision and hearing • Paralysis treatment • Prosthetic devices (legs, hands etc) • Provide a means of communication to completely paralyzed patients • Surgically implanted devices used as replacement • for paralyzed patients BCI

30. General application • Control a robot • Playing games • For physically weak persons to handle the computer • Cursor control • Allow those with poor muscle control to • communicate and control physical devices BCI

31. Example of BCI application A phsically handicapped man operates a BCI wheelchair BCI

32. More examples Japanese student walking in the virtual world with the character controlled by his brain waves. A single handed man interfaced with BCI BCI

33. ADVANTAGES • BCIs will help creating a Direct communication between a human or animal brain and computers. • Also it provides better living, more features, more advancement in technologies etc. • High Precision (can be used reliably) • Low bandwidth BCI

34. Difficulty in Implementation of BCI: • COST require for BCI is very high. • It is RISKy, because it operates with brain. • Effective BCI technique requires invasive method. • Requires magnetically shielded room and special kind of helmet. • It is SLOW BCI

35. Future Work • Improving physical methods for gathering EEGs • Improving generalization • Improving knowledge of how to interpret waves

36. Future developments • Better signal detection • Shortening training time • Improving learning (neurobiological and psychological basis) • New recording methods (NIRS, ECoG) • Broader range of applications (interface to commercially available assistive devices; treatment of diseases) BCI

37. Conclusion • BCI is highly promising. • Provide high standard of living. • Extend our limits. • Impart a new level to the popular quote- “I think therefore I am!” BCI

38. Any……??? Thank u… BCI