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BCI Systems. Brendan Allison, Ph.D. Institute for Automation University of Bremen 6 November, 2008. What is a BCI?. A BCI enables communication without movement. Some patients cannot use any interface requiring movement. What is a BCI?. What is a BCI?.

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Bci systems

BCI Systems

Brendan Allison, Ph.D.

Institute for Automation

University of Bremen

6 November, 2008


What is a BCI?

A BCI enables communication without movement.

Some patients cannot use any interface requiring movement.



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.


What is a BCI?

  • BCIs may be:

  • Non-invasive (usually EEG)

  • Invasive

    • ECoG (surface of cortex)

    • depth recording (in brain)


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.


How do EEGs work?

This activity may be detectable to electrodes on the scalp.

Conventional electrode caps from EGI, Neuroscan, and Electro-Cap.


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).


How do EEGs work?

QUASAR Hybrid or eIBE sensors

QUASAR IBE Electrodes

Audio Headset

EOG/EEG Glasses


How do EEGs work?

Emotiv and NeuroSky systems


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)


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


What isn’t a BCI?

yes

hello

pain

BCIs cannot read minds or literally interpret mental activity.


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


What isn’t a BCI?

More bci fi ….

Brainstorm

Total Recall

Minority Report

The Lawnmower Men

The Govenator!!


What isn’t a BCI?

  • BCIs cannot:

  • Read your thoughts.


What isn’t a BCI?

  • BCIs cannot:

  • Operate without your knowledge or free will.


What isn’t a BCI?

  • BCIs cannot:

  • Write to the brain.


What isn’t a BCI?

  • BCIs cannot:

  • Repair injured areas.

  • (??)


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


What is a BCI?

BCIs rely on voluntary mental activities such as:

Imagined movement

Torrey Pines golf course


What is a BCI?

BCIs rely on voluntary mental activities such as:

Emotional imagery


What is a BCI?

BCIs rely on voluntary mental activities such as:

Selective attention

(SSVEP)


What is a BCI?

BCIs rely on voluntary mental activities such as:

Selective attention

(P300)


What is a BCI?

BCIs rely on voluntary mental activities such as:

Certain mental tasks

6

X 9

42

Object rotation

Singing

Math


What is a BCI?

  • Emerging new tasks for BCIs:

  • Perceived error

  • Imagined music

  • New modalities and variants

  • (Passive BCIs):

  • Anticipation

  • Alertness/fatigue

  • Familiarity/recognition


Components

  • How do BCIs work?

  • General Schematic

  • P300 BCI

  • Mu BCI

  • Other BCIs


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


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)


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



Acquisition

Many sources create noise.

Electrode cap

Raw EEGs from a field setting


Acquisition

A headband used for a 1D mu BCI (Pineda et al., 2003)

Several brain areas responsible for movement.


Extraction, Translation

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


Cortical Neurons

Top: Utah intracranial electrode array

Bottom: Cone electrode

Recording from a neuron (Kandel et al., 1988)


Cortical Neurons

A patient with an implanted BCI (Cyberkinetics, Inc.)

A severely disabled subject controls a switch (Kennedy et al., 2004)


Cortical Neurons

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


Selective attention: P300

The P300 only occurs after target flashes (Allison and Pineda, 2003).


Environment

User task:

Imagine movement to move the cursor down.

Relax to move it up.

A mu BCI using BCI2000 (Schalk et al., 2004)


Acquisition, Extraction

The P300 only occurs after target flashes (Allison, 2003).

It is often largest over site Cz or Pz (central or parietal areas).


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