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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


Bci systems

What is a BCI?

A BCI enables communication without movement.

Some patients cannot use any interface requiring movement.


Bci systems

What is a BCI?


Bci systems

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.


Bci systems

What is a BCI?

  • BCIs may be:

  • Non-invasive (usually EEG)

  • Invasive

    • ECoG (surface of cortex)

    • depth recording (in brain)


Bci systems

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.


Bci systems

How do EEGs work?

This activity may be detectable to electrodes on the scalp.

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


Bci systems

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).


Bci systems

How do EEGs work?

QUASAR Hybrid or eIBE sensors

QUASAR IBE Electrodes

Audio Headset

EOG/EEG Glasses


Bci systems

How do EEGs work?

Emotiv and NeuroSky systems


Bci 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)


Bci systems

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


Bci systems

What isn’t a BCI?

yes

hello

pain

BCIs cannot read minds or literally interpret mental activity.


Bci systems

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


Bci systems

What isn’t a BCI?

More bci fi ….

Brainstorm

Total Recall

Minority Report

The Lawnmower Men

The Govenator!!


Bci systems

What isn’t a BCI?

  • BCIs cannot:

  • Read your thoughts.


Bci systems

What isn’t a BCI?

  • BCIs cannot:

  • Operate without your knowledge or free will.


Bci systems

What isn’t a BCI?

  • BCIs cannot:

  • Write to the brain.


Bci systems

What isn’t a BCI?

  • BCIs cannot:

  • Repair injured areas.

  • (??)


Bci systems

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


Bci systems

What is a BCI?

BCIs rely on voluntary mental activities such as:

Imagined movement

Torrey Pines golf course


Bci systems

What is a BCI?

BCIs rely on voluntary mental activities such as:

Emotional imagery


Bci systems

What is a BCI?

BCIs rely on voluntary mental activities such as:

Selective attention

(SSVEP)


Bci systems

What is a BCI?

BCIs rely on voluntary mental activities such as:

Selective attention

(P300)


Bci systems

What is a BCI?

BCIs rely on voluntary mental activities such as:

Certain mental tasks

6

X 9

42

Object rotation

Singing

Math


Bci systems

What is a BCI?

  • Emerging new tasks for BCIs:

  • Perceived error

  • Imagined music

  • New modalities and variants

  • (Passive BCIs):

  • Anticipation

  • Alertness/fatigue

  • Familiarity/recognition


Bci systems

Components

  • How do BCIs work?

  • General Schematic

  • P300 BCI

  • Mu BCI

  • Other BCIs


Bci systems

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


Bci systems

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)


Bci systems

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


Bci systems

Motor imagery: ERD


Bci systems

Acquisition

Many sources create noise.

Electrode cap

Raw EEGs from a field setting


Bci systems

Acquisition

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

Several brain areas responsible for movement.


Bci systems

Extraction, Translation

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


Bci systems

Cortical Neurons

Top: Utah intracranial electrode array

Bottom: Cone electrode

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


Bci systems

Cortical Neurons

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

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


Bci systems

Cortical Neurons

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


Bci systems

Selective attention: P300

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


Bci systems

Environment

User task:

Imagine movement to move the cursor down.

Relax to move it up.

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


Bci systems

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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