eeg signal background and real-time processing
TRANSCRIPT
![Page 1: EEG signal background and real-time processing](https://reader033.vdocuments.net/reader033/viewer/2022051202/588724261a28abfb0b8b629d/html5/thumbnails/1.jpg)
EEG signal background and real-time processing
Robert Oostenveld
Donders Institute, Radboud University, Nijmegen, NL
Karolinska Institute, Stockholm, SE
![Page 2: EEG signal background and real-time processing](https://reader033.vdocuments.net/reader033/viewer/2022051202/588724261a28abfb0b8b629d/html5/thumbnails/2.jpg)
Outline
Brain activity and how to measure it
The source of EEG signals
Controlling alpha oscillations
Realtime processing and closed-loop systems
![Page 3: EEG signal background and real-time processing](https://reader033.vdocuments.net/reader033/viewer/2022051202/588724261a28abfb0b8b629d/html5/thumbnails/3.jpg)
Brain activity
spiking activity
(local) field potentials
magnetic fields
blood flow
blood oxigenation
biochemical concentrations
![Page 4: EEG signal background and real-time processing](https://reader033.vdocuments.net/reader033/viewer/2022051202/588724261a28abfb0b8b629d/html5/thumbnails/4.jpg)
Methods to record brain activity
(sharp-tipped electrodes)
multi electrode array (c.f. Utah array)
sEEG multitrodes
ECoG surface electrodes
(voltage sensitive dyes)
scalp EEG
MEG
NIRS
arterial spin labeling
BOLD
MRS
![Page 5: EEG signal background and real-time processing](https://reader033.vdocuments.net/reader033/viewer/2022051202/588724261a28abfb0b8b629d/html5/thumbnails/5.jpg)
EEG Instrumentation
![Page 6: EEG signal background and real-time processing](https://reader033.vdocuments.net/reader033/viewer/2022051202/588724261a28abfb0b8b629d/html5/thumbnails/6.jpg)
Recording EEG
![Page 7: EEG signal background and real-time processing](https://reader033.vdocuments.net/reader033/viewer/2022051202/588724261a28abfb0b8b629d/html5/thumbnails/7.jpg)
Outline
Brain activity and how to measure it
The source of EEG signals
Controlling alpha oscillations
Realtime processing and closed-loop systems
![Page 8: EEG signal background and real-time processing](https://reader033.vdocuments.net/reader033/viewer/2022051202/588724261a28abfb0b8b629d/html5/thumbnails/8.jpg)
![Page 9: EEG signal background and real-time processing](https://reader033.vdocuments.net/reader033/viewer/2022051202/588724261a28abfb0b8b629d/html5/thumbnails/9.jpg)
![Page 10: EEG signal background and real-time processing](https://reader033.vdocuments.net/reader033/viewer/2022051202/588724261a28abfb0b8b629d/html5/thumbnails/10.jpg)
![Page 11: EEG signal background and real-time processing](https://reader033.vdocuments.net/reader033/viewer/2022051202/588724261a28abfb0b8b629d/html5/thumbnails/11.jpg)
pre-synapticaction potential
post-synapticpotential
![Page 12: EEG signal background and real-time processing](https://reader033.vdocuments.net/reader033/viewer/2022051202/588724261a28abfb0b8b629d/html5/thumbnails/12.jpg)
electric current
![Page 13: EEG signal background and real-time processing](https://reader033.vdocuments.net/reader033/viewer/2022051202/588724261a28abfb0b8b629d/html5/thumbnails/13.jpg)
Superposition of source activity
![Page 14: EEG signal background and real-time processing](https://reader033.vdocuments.net/reader033/viewer/2022051202/588724261a28abfb0b8b629d/html5/thumbnails/14.jpg)
Standard electrode placement
![Page 15: EEG signal background and real-time processing](https://reader033.vdocuments.net/reader033/viewer/2022051202/588724261a28abfb0b8b629d/html5/thumbnails/15.jpg)
High-density electrode placement
![Page 16: EEG signal background and real-time processing](https://reader033.vdocuments.net/reader033/viewer/2022051202/588724261a28abfb0b8b629d/html5/thumbnails/16.jpg)
Outline
Brain activity and how to measure it
The source of EEG signals
Controlling alpha oscillations – and others
Realtime processing and closed-loop systems
![Page 17: EEG signal background and real-time processing](https://reader033.vdocuments.net/reader033/viewer/2022051202/588724261a28abfb0b8b629d/html5/thumbnails/17.jpg)
Adapted from Jensen & Mazaheri (2010) Frontiers Neurosci.
a
b
c
![Page 18: EEG signal background and real-time processing](https://reader033.vdocuments.net/reader033/viewer/2022051202/588724261a28abfb0b8b629d/html5/thumbnails/18.jpg)
Adapted from Jensen & Mazaheri (2010) Frontiers Neurosci.
a
b
c
![Page 19: EEG signal background and real-time processing](https://reader033.vdocuments.net/reader033/viewer/2022051202/588724261a28abfb0b8b629d/html5/thumbnails/19.jpg)
Adapted from Jensen & Mazaheri (2010) Frontiers Neurosci.
a
b
c
High alpha = inattention
Low alpha = attending
![Page 20: EEG signal background and real-time processing](https://reader033.vdocuments.net/reader033/viewer/2022051202/588724261a28abfb0b8b629d/html5/thumbnails/20.jpg)
Other brain signals used in EEG-BCI
pay attention to one feature, ignore others
SSVEP – steady state visual evoked potential
P300 – positivity around 300 ms after stimulus
imagine movements
Mu rhythm – mix of 10 and 20 Hz over sensory-motor regions
![Page 21: EEG signal background and real-time processing](https://reader033.vdocuments.net/reader033/viewer/2022051202/588724261a28abfb0b8b629d/html5/thumbnails/21.jpg)
Outline
Brain activity and how to measure it
The source of EEG signals
Controlling alpha oscillations
Realtime processing and closed-loop systems
![Page 22: EEG signal background and real-time processing](https://reader033.vdocuments.net/reader033/viewer/2022051202/588724261a28abfb0b8b629d/html5/thumbnails/22.jpg)
Conventional experiment
M/EEG, fMRI,...data source
analysis
stimuluspresentation hard disk
hard disk
collect many data from many subjects, analyse later
![Page 23: EEG signal background and real-time processing](https://reader033.vdocuments.net/reader033/viewer/2022051202/588724261a28abfb0b8b629d/html5/thumbnails/23.jpg)
Realtime experiment / BCI loop
• Challenge: timely handling of incoming data, preprocessing, analysis, sending outputs
M/EEG, fMRI,...data source
preprocessingfeature extract.
analysis
stimuluspresentation
![Page 24: EEG signal background and real-time processing](https://reader033.vdocuments.net/reader033/viewer/2022051202/588724261a28abfb0b8b629d/html5/thumbnails/24.jpg)
Buffering relaxes timing constraints...
• analysis side can pick data when convenient
• can look back in time if needed
M/EEG, fMRI,...data source
analysissoftware
stimuluspresentation
datastream or
ringbuffer
![Page 25: EEG signal background and real-time processing](https://reader033.vdocuments.net/reader033/viewer/2022051202/588724261a28abfb0b8b629d/html5/thumbnails/25.jpg)
... and facilitates talking to different devices more easily
MEG: CTF,Neuromag
fMRI:Siemens
EEG: TMSI, Biosemi, OpenBCI
NIRS:Artinis
analysissoftware
FieldTripbuffer
ECoG:Neuralynx,Micromed
![Page 26: EEG signal background and real-time processing](https://reader033.vdocuments.net/reader033/viewer/2022051202/588724261a28abfb0b8b629d/html5/thumbnails/26.jpg)
Multiple applications for analysis etc.
applications can communicate through buffer („events“)
FieldTripbuffer
analysissoftware
analysissoftware
otherplatforms
onlinedisplay
MEG: CTF,Neuromag
fMRI:Siemens
EEG: TMSI, Biosemi, OpenBCI
NIRS:Artinis
ECoG:Neuralynx,Micromed
![Page 27: EEG signal background and real-time processing](https://reader033.vdocuments.net/reader033/viewer/2022051202/588724261a28abfb0b8b629d/html5/thumbnails/27.jpg)
Extends naturally to pipelines
EEG system
„raw“EEGdata
translate into control signals
filter & re-reference
„clean“EEG data
monitor data qualitye.g. drift
loose electrodes
![Page 28: EEG signal background and real-time processing](https://reader033.vdocuments.net/reader033/viewer/2022051202/588724261a28abfb0b8b629d/html5/thumbnails/28.jpg)
Concepts of pipeline sequence
artifactdetection
spectral estimation
classificationor regression
rawdata
“control” signal
many numbers few numbers
![Page 29: EEG signal background and real-time processing](https://reader033.vdocuments.net/reader033/viewer/2022051202/588724261a28abfb0b8b629d/html5/thumbnails/29.jpg)
amplifier analysis computer
storage
Controlled device
Experimental controlTherapeutic operator
Subject
data
feedback signal
EE
G
co
ntro
l sig
na
l
da
taOptimization
Behavior, analysis and control signals
In green the basic minimal BCI setup.
In pink the additional feedback signal for a neurofeedback system.
In orange the registration and storage of all data to reconstruct and analyze the neurofeedback system.
In yellow the optimization of the analysis and/or control.
In red the control of the experimentor or therapist.
co
ntr
ol fe
ed
back
![Page 30: EEG signal background and real-time processing](https://reader033.vdocuments.net/reader033/viewer/2022051202/588724261a28abfb0b8b629d/html5/thumbnails/30.jpg)
![Page 31: EEG signal background and real-time processing](https://reader033.vdocuments.net/reader033/viewer/2022051202/588724261a28abfb0b8b629d/html5/thumbnails/31.jpg)
Pyt
ho
nm
od
ule
s
Red
is
FieldTrip buffer
USBCV/gate
webserver
USB-MIDI interface
OpenBCIinterface
audience/subjectartist/performer
scientist/engineer