1. Electroencephalogram (EEG)
“Extracellular currents”
Summed activity of post-synaptic currents generated by compensatory currents in the extracellular space
Summation of the synchronous activity of thousands of neurons that have similar spatial orientation, radial to the scalp
Currents that are tangential to the scalp are not picked up by the EEG
Activity from deep sources is more difficult to detect than currents near the skull

2. History
Duboi-Reymond (1848): reported the presence of electrical signals
Caton (1875): measured “feeble” currents on the rabbit scalp
Berger (1929)
measured electrical signals in human
Alpha and Beta waves, eye closed and open, mental task
Sleep and Awake
Illness and EEG
Drug and EEG: Phenobarbital, morphine, cocaine
Telepathic transmission
s: EEG used in psychiatric and neurological sciences relying on visual inspection of EEG patterns
1960s-70s: witness emergence of Quantitative EEG and confirmation of hemispheric specialization, e.g., left brain verbal and right brain spatial.
1980s+: observation of biofeedback

3. Waveform

4. Wave differentiation
Alpha (8-12 Hz): posterior head regions, in adult in awake but relaxed. attenuate with eye opening or mental exertion
Beta (12-30 Hz): active, busy or anxious thinking and active concentration
Gamma ( Hz): certain cognitive or motor function, most often artifactual
Delta (<3 Hz): in adults in slow wave sleep / in babies
Theta (4-7 Hz): in young children / in drowsiness or arousal in older children and adults / in meditation

5. The original figure of 10-20 system (Jasper, 1958)

6. The international 10-20 system
A = Ear lobe, C = central, Pg = nasopharyngeal, P = parietal, F = frontal, Fp = frontal polar, O = occipital.

7. American Electroencephalographic Society (Sharbrough, 1991)

8. Lobes of the Brain
Frontal Lobes: Personality, emotions, problem solving.
Parietal lobes: Cognition, spatial relationships and mathematical abilities, nonverbal memory.
Occipital lobes: Vision, color, shape and movement.
Temporal lobes: Speech and auditory processing, language comprehension, long-term memory.

9. Can EEG work for BCI?
Electrical activity generated by complex system of billions of neurons
Brain is a “gelatinous mass” suspended in a conducting fluid
Difficult to “register” electrode location
Artifacts from motion, eyeblinks, swallows, heartbeat, sweating…
Food, age, time of day, fatigue, motivation of subject
Many EEG studies have reported reproducible changes in brain dynamics that are task dependent!
Patients may “correct” their waveforms to achieve a normal state
Kamiya (1962): demonstrated the controllability of alpha waves
Communication in morse code by turning alpha waves on and off
Stress management and sleep therapy
Move a pac-man by stimulating alpha and beta waves
Note that artifacts are a serious problem for real-time biofeedback applications

10. Matrix?

11. Real story 1: Monkey think, Robot Do
Learning to control a brain-machine interface for reaching and grasping by primates. Nicolelis et al., PLoS Biology 2003

12. Real story 2: ‘Ratbot’ Rat navigation guided by remote control
Chapin et al., Nature, 2002

13. Motivation for BCI/BMI Research
In USA, more than 200,000 patients live with the motor sequelae (consequences) of serious injury.
There are two ways to help them restore some motor function:
Repair the damaged nerve axons
Build neuroprosthetic device

14. Brain Computer Interface (BCI)

16. EEG-based BCI non-invasive promising for some therapies time-consuming
not suitable for precise control
Mussa-Ivaldi & Miller, 2003

17. Control home appliances by mind Tsinghua Group Gao et al
Appliance control
Make phone call

18. Type words by mind Tübingen Group Birbaumer et al
Type words by mind Tübingen Group Birbaumer et al., 2000, Hinterberger et al., 2004

19. Help impaired hand to grasp by mind Graz Group Pfurtscheller et al

20. Play video games by mind
ECoG based BCI Video
Pfurtscheller et al., 2003
Leuthardt et al.,2004

21. Neuron Spike based BMI high speed real time control
precise control of movement
invasive
high risk for clinical application
Nicolelis, 2001

22. Monkey control robot arm by mind Duke Group Nicolelis et al

23. Real time control of 2D/3D movement Donoghue et al, 2002, Schwartz et al.,2002
2D movement control
3D movement control

24. Take home message
Origin of EEG
Pros and Cons of EEG in making BCI