BCI Systems

1. BCI Systems Brendan Allison, Ph.D. Institute for Automation University of Bremen 6 November, 2008

2. What is a BCI? A BCI enables communication without movement. Some patients cannot use any interface requiring movement.

3. What is a BCI?

4. What is a BCI? Most BCIs translate your brain’s electrical activity (EEGs) into messages or commands. Performing mental tasks produces electrical activity detectable with electrode caps.

5. What is a BCI? • BCIs may be: • Non-invasive (usually EEG) • Invasive • ECoG (surface of cortex) • depth recording (in brain)

6. How do EEGs work? Neural communication produces electrical activity. Electrical activity in a single neuron. When a neuron is active, its voltage may change by 100 mV or more.

7. How do EEGs work? This activity may be detectable to electrodes on the scalp. Conventional electrode caps from EGI, Neuroscan, and Electro-Cap.

8. How do EEGs work? • Newer EEG recording systems: • Require less or no prep time and skill • Require less or no gel • Require fewer electrodes • Are more portable • Handle artifacts better • Are wireless • Are cheaper Field recording systems from Quasar, Advanced Brain Monitoring, and Pineda et al (2003).

9. How do EEGs work? QUASAR Hybrid or eIBE sensors QUASAR IBE Electrodes Audio Headset EOG/EEG Glasses

10. How do EEGs work? Emotiv and NeuroSky systems

11. How do EEGs work? Invasive BCIs record activity from electrodes under the scalp. Pyramidal neurons (Kandel et al., 1988) Electrocorticogram (ECoG) recording montage in a human patient. (Leuthardt et al., 2004)

12. How do EEGs work? • Other functional imaging approaches: • Functional Magnetic Resonance Imaging (fMRI) • Magnetoencephalography (MEG) • Positron Emission Tomography (PET) • Functional Near Infrared (fNIR) An MEG machine A functional MRI Functional Near Infrared

13. What isn’t a BCI? yes hello pain BCIs cannot read minds or literally interpret mental activity.

14. What isn’t a BCI? BCIs are a popular topic in sci fi! Firefox Strange Days Neuromancer The Matrices Johnny Mnemonic Star Trek: The Cage Dreamscape The X – Mens

15. What isn’t a BCI? More bci fi …. Brainstorm Total Recall Minority Report The Lawnmower Men The Govenator!!

16. What isn’t a BCI? • BCIs cannot: • Read your thoughts.

17. What isn’t a BCI? • BCIs cannot: • Operate without your knowledge or free will.

18. What isn’t a BCI? • BCIs cannot: • Write to the brain.

19. What isn’t a BCI? • BCIs cannot: • Repair injured areas. • (??)

20. What isn’t a BCI? • These similar approaches are not BCIs: ?? • Biofeedback • Prosthetics • Retinal or cochlear implants • Medical EEGs • EEG or fMRI Lie Detection • Neuromarketing • Employee screening • Attention or fatigue monitors

21. What is a BCI? BCIs rely on voluntary mental activities such as: Imagined movement Torrey Pines golf course

22. What is a BCI? BCIs rely on voluntary mental activities such as: Emotional imagery

23. What is a BCI? BCIs rely on voluntary mental activities such as: Selective attention (SSVEP)

24. What is a BCI? BCIs rely on voluntary mental activities such as: Selective attention (P300)

25. What is a BCI? BCIs rely on voluntary mental activities such as: Certain mental tasks 6 X 9 42 Object rotation Singing Math

26. What is a BCI? • Emerging new tasks for BCIs: • Perceived error • Imagined music • New modalities and variants • (Passive BCIs): • Anticipation • Alertness/fatigue • Familiarity/recognition

27. Components • How do BCIs work? • General Schematic • P300 BCI • Mu BCI • Other BCIs

28. Components • A BCI requires the following: • At least 2 electrodes • An amplifier designed for EEGs • A mediocre personal computer • An A/D card in the computer • Software

29. Components • All BCIs have at least four components: • Signal Acquisition • Feature Extraction • Translation Algorithm • Operating Environment The Four BCI Components (Wolpaw et al., 2002; Allison et al., 2007)

30. Components Acquisition: The user performs a task that produces a distinct EEG signature for that BCI Extraction: Salient features are extracted from the EEG Translation: A pattern classification system uses these EEG features to determine which task the user performed Environment: The BCI presents feedback to the user, and forms a message or command

31. Motor imagery: ERD

32. Acquisition Many sources create noise. Electrode cap Raw EEGs from a field setting

33. Acquisition A headband used for a 1D mu BCI (Pineda et al., 2003) Several brain areas responsible for movement.

34. Extraction, Translation Mu activity used for one dimensional control (Wolpaw et al., 1991)

35. Cortical Neurons Top: Utah intracranial electrode array Bottom: Cone electrode Recording from a neuron (Kandel et al., 1988)

36. Cortical Neurons A patient with an implanted BCI (Cyberkinetics, Inc.) A severely disabled subject controls a switch (Kennedy et al., 2004)

37. Cortical Neurons ECog activity in several human patients during hand or tongue movement (Miller, in press)

38. Selective attention: P300 The P300 only occurs after target flashes (Allison and Pineda, 2003).

39. Environment User task: Imagine movement to move the cursor down. Relax to move it up. A mu BCI using BCI2000 (Schalk et al., 2004)

40. Acquisition, Extraction The P300 only occurs after target flashes (Allison, 2003). It is often largest over site Cz or Pz (central or parietal areas).