BCI I: EEG-Based

Cognitive Status Monitoring

Scott Makeig & Tzyy-Ping Jung

University of California San Diego

November 13, 2007

Passive = Cognitive Status Monitoring (CSM)

Active = Brain-Actuated control (BAC)

• Move the cursor• Move the wheelchair• Move the arm• Evolve the video game

Brain-Computer Interfaces (BCI)

Interactive = Bio/Neurofeedback

Brain-Computer Interfaces

DIRECT = Purely brain-based MIXED = Using a mixture of bio-signals INDIRECT = Based on EMG signals

DIRECT = EEG-based

LFP-based

Spike-based

Brain-Computer Interfaces

Measure = Unstimulated

Evoked

Induced

Cognitive status monitoring

Possible …• Attending or not attending?• Encoding or not encoding?• Rewarded or not? • Threatened or not?• Sure or unsure?• Competent or incompetent?• Lost or found?

Currently …• Alive or dead?• Alert or asleep?• Task loaded or overloaded?

Makeig & Inlow, 1993

Erratic Performance Records

Makeig & Inlow, 1993

Mean Performance Fluctuation Spectrum

Makeig & Inlow, 1993

Single Session Changes in EEG Power and Performance

Makeig & Inlow, 1993

Frequency (Hz)50C

oh

eren

ce

0.5

0.8

3.1 9.8 13.4 Hz

Coherence of Spectral and Performance Changes

Per

form

ance

Cyc

le L

engt

h

Makeig & Inlow, 1993

Frequency (Hz)

Co

rrel

atio

n w

ith

Lo

cal

Err

or

Rat

e

EEG Spectral Changes with Performance Decline are Similar for Most Subjects

Makeig & Inlow, 1993

EEG Spectral Changes with Performance Decline are Subject-Specific

Makeig & Inlow, 1993

EEG Spectral Changes are Tightly Linked to Performance Changes

Makeig & Jung, 1996

EEG Spectral Changes Linked to Performance Changes During Periods of Intermittent Performance

Frequency (Hz)

Error R

ate

(%)P

ower

(dB

)Pre-Hit (Cz)

Makeig & Jung, 1996

Frequency (Hz)

Error R

ate

(%)

Pow

er (

dB)

Pre-Lapse (Cz)

EEG Spectral Changes Linked to Performance Changes During Periods of Intermittent Performance

Makeig & Jung, 1996

Frequency (Hz)

Error R

ate

(%)

Pow

er (

dB)

Lapse - Hit (Cz)

EEG Spectral Changes Linked to Performance Changes During Periods of Intermittent Performance

Makeig & Jung, 1996

EEG Spectral Changes Around a Lapse

Frequency (Hz) Target Latency (s)

P

ower

(dB

)Lapse - Hit (Cz)

Makeig & Jung, 1996

EEG Spectral Changes Around a Lapse

E

rror

Rat

e

Target Latency (s)

P

ower (rel. dB

)

Makeig, Jung & Sejnowski, 2000

EEG Spectral Changes Around a Lapse

E

rror

Rat

e

Target Latency (s)

P

ower (rel. dB

)

Cognitive Status Monitoring

• EEG-based alertness monitoring is possible

• Individualized models likely more accurate

• Natural EEG rhythms and time scales exist