Neuroimaging: Intracortical, fMRI, EEG
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Transcript of Neuroimaging: Intracortical, fMRI, EEG
MACHINE LEARNING ON NEUROIMAGING DATA
Ilya Kuzovkin
AACIMP, August 2014
LECTURE 1: NEUROIMAGING TECHNIQUES
THE COURSE
NEUROIMAGING DATA
L1
P1
THE COURSE
NEUROIMAGING DATA
MACHINE LEARNING
L1
P1
L2
P2+
THE COURSE
NEUROIMAGING DATA
MACHINE LEARNING
BRAIN-COMPUTER INTERFACE
L1
P1
L2
P2 P3+ =
PART I INTRACORTICAL
SPIKE
http://faculty.tcc.edu/mmitchell/142/ap-graph1.jpg
SPIKE
http://faculty.tcc.edu/mmitchell/142/ap-graph1.jpg
How can voltage be negative?
http://newton.umsl.edu/tsytsarev_files/neuron_electrode.JPG
ELECTRODES
THE SIGNAL
• Local Field Potential
http://www.frontiersin.org/files/Articles/414/fnins-02-037/image_m/fnins-02-037-g001.jpg http://lifesciences.ieee.org/images/stories/life-sciences/2012-01-spike-01_l.png
THE SIGNAL • Multi-unit spikes
• Local Field Potential
http://www.frontiersin.org/files/Articles/414/fnins-02-037/image_m/fnins-02-037-g001.jpg http://lifesciences.ieee.org/images/stories/life-sciences/2012-01-spike-01_l.png
THE SIGNAL • Multi-unit spikes
• Local Field Potential
Spike sorting
http://www.frontiersin.org/files/Articles/414/fnins-02-037/image_m/fnins-02-037-g001.jpg http://lifesciences.ieee.org/images/stories/life-sciences/2012-01-spike-01_l.png
THE SIGNAL
http://www.frontiersin.org/files/Articles/414/fnins-02-037/image_m/fnins-02-037-g001.jpg http://lifesciences.ieee.org/images/stories/life-sciences/2012-01-spike-01_l.png
• Multi-unit spikes
• Local Field Potential
• Single-unit spikes
Spike sorting
For each measured neuron we record the time moments when it spiked
RASTER PLOT
RASTER PLOT
What is on the X axis?
RASTER PLOT
Time
RASTER PLOT
What is on the Y axis?
Time
RASTER PLOT
Time
Neu
rons
RASTER PLOT
Time
Neu
rons
rastrum
PSTHPost-Stimulus Time Histogram
PSTHPost-Stimulus Time Histogram
Neu
rons
\ Tr
ials
PSTHPost-Stimulus Time Histogram
Neu
rons
\ Tr
ials
100
ms
PSTHPost-Stimulus Time Histogram
Neu
rons
\ Tr
ials
100
ms
100
ms
PSTHPost-Stimulus Time Histogram
Neu
rons
\ Tr
ials
100
ms
100
ms
100
ms
100
ms
PSTHPost-Stimulus Time Histogram
Neu
rons
\ Tr
ials
100
ms
100
ms
100
ms
100
ms
31 s
pike
s
34 s
pike
s
27 s
pike
s
218
spik
es
33 s
pike
s
PSTH
Time
Neu
rons
\ Tr
ials
Post-Stimulus Time Histogram
PSTH
Time
Neu
rons
\ Tr
ials
Post-Stimulus Time Histogram
What is on the Y axis?
PSTH
Time
Neu
rons
\ Tr
ials
Post-Stimulus Time Histogram
Spik
es p
er 1
00 m
s
PSTH
Time
Neu
rons
\ Tr
ials
Post-Stimulus Time Histogram
Spik
es p
er 1
00 m
s
TUNING CURVE
http://www.beatricebiologist.com/2012/11/types-of-cells.html
TUNING CURVE
http://www.beatricebiologist.com/2012/11/types-of-cells.html
45
TUNING CURVE
http://www.beatricebiologist.com/2012/11/types-of-cells.html
45
TUNING CURVE
http://www.beatricebiologist.com/2012/11/types-of-cells.html
40 spikes per second (40 Hz)45
TUNING CURVE
http://www.beatricebiologist.com/2012/11/types-of-cells.html
40 spikes per second (40 Hz)
0
45
TUNING CURVE
http://www.beatricebiologist.com/2012/11/types-of-cells.html
40 spikes per second (40 Hz)
7 spikes per second (7 Hz)0
45
TUNING CURVE
http://www.beatricebiologist.com/2012/11/types-of-cells.html
40 spikes per second (40 Hz)
7 spikes per second (7 Hz)0
45
TUNING CURVE
http://www.beatricebiologist.com/2012/11/types-of-cells.html
40 spikes per second (40 Hz)
7 spikes per second (7 Hz)0
45
TUNING CURVE
http://www.beatricebiologist.com/2012/11/types-of-cells.html
40 spikes per second (40 Hz)
7 spikes per second (7 Hz)
What do you expect to see on this plot?0
45
TUNING CURVE
http://www.beatricebiologist.com/2012/11/types-of-cells.html
40 spikes per second (40 Hz)
7 spikes per second (7 Hz)0
45
TUNING CURVE
http://www.beatricebiologist.com/2012/11/types-of-cells.html
40 spikes per second (40 Hz)
7 spikes per second (7 Hz)0
45
SUMMARY
• High spatial resolution (up to single neuron)
!• High temporal resolution
SUMMARY
• High spatial resolution (up to single neuron)
!• High temporal resolution
What does “spatial resolution” mean?
SUMMARY
• Requires surgery !• Localized
What does “temporal resolution” mean?
• High spatial resolution (up to single neuron)
!• High temporal resolution
• High spatial resolution (up to single neuron)
!• High temporal resolution
SUMMARY
• Requires surgery !• Localized
• High spatial resolution (up to single neuron)
!• High temporal resolution
SUMMARY
• Requires surgery !• Localized
Very informative and precise, but not applicable to general
audience due to surgery.
PART II FMRI
http://www.csulb.edu/~cwallis/482/fmri/fmri.h3.gif http://neuro.mediasauce.com/images/fmri_machine.png
NUCLEAR MAGNETIC RESONANCE
Physical phenomenon in which nucleus of an atom can absorb or reemit
electromagnetic radiation if placed in a magnetic field
NUCLEAR MAGNETIC RESONANCE
Physical phenomenon in which nucleus of an atom can absorb or reemit
electromagnetic radiation if placed in a magnetic field
NUCLEAR MAGNETIC RESONANCE
Physical phenomenon in which nucleus of an atom can absorb or reemit
electromagnetic radiation if placed in a magnetic field
NUCLEAR MAGNETIC RESONANCE
Physical phenomenon in which nucleus of an atom can absorb or reemit
electromagnetic radiation if placed in a magnetic field.
SPIN
Spin-UP +1/2
Spin-DOWN -1/2
http://www.markusehrenfried.de/science/physics/hermes/whatisspin.html
SPIN
Spin-UP +1/2
Spin-DOWN -1/2
http://www.markusehrenfried.de/science/physics/hermes/whatisspin.html
Nothing actually spins in there. No analogy in classical mechanics.
SPIN
Spin-UP +1/2
Spin-DOWN -1/2
Nothing actually spins in there. No analogy in classical mechanics.
But why call it spin then?http://www.markusehrenfried.de/science/physics/hermes/whatisspin.html
http://www.howequipmentworks.com/physics/medical_imaging/mri/magnetic_resonance_imaging.html
NOT A JOKE
Six known types of quarks and their official names. So spin is not that bad.
MAGNETIC MOMENT
MAGNETIC MOMENT
Particle with non-zero nuclear spin is like a
small magnet.
MAGNETIC MOMENT
or ?
Particle with non-zero nuclear spin is like a
small magnet.
MAGNETIC MOMENT
or ?
Particle with non-zero nuclear spin is like a
small magnet.
MAGNETIC MOMENT
Particle with non-zero nuclear spin is like a
small magnet.
IN A MAGNETIC FIELD
What happens to a magnet if you put it in a magnetic field?
IN A MAGNETIC FIELD
What happens to a magnet if you put it in a magnetic field?
IN A MAGNETIC FIELD
IN A MAGNETIC FIELD
IN A MAGNETIC FIELD
IN A MAGNETIC FIELD
Stronger field — larger energy gap
Nuclear Magnetic Resonance
Nuclear Magnetic Resonance
Nuclear Magnetic Resonance
?Nuclear Magnetic Resonance
RADIO FREQUENCY PULSE
RADIO FREQUENCY PULSE
We can give energy to a particle
and move it to a higher energy level
RADIO FREQUENCY PULSE
We can give energy to a particle
and move it to a higher energy level
To do that we send an electromagnetic wave
RADIO FREQUENCY PULSE
We can give energy to a particle
and move it to a higher energy level
Nucleus will absorb energy only if frequency of the wave is correct for
• the nucleus we work with • strength of the magnetic field
To do that we send an electromagnetic wave
RELAXATION
Now we stop the pulse
RELAXATION
Now we stop the pulse
RELAXATION
Nucleus will give out same amount of energy in the form of electromagnetic radiation.
Now we stop the pulse
Nuclear Magnetic Resonance Imaging
Nuclear Magnetic Resonance Imaging
Nuclear Magnetic Resonance Imaging
HYDROGEN
HYDROGEN
Possible spin states +1/2 or -1/2
http://www.howequipmentworks.com/physics/medical_imaging/mri/magnetic_resonance_imaging.html
HYDROGEN IN A MAGNETIC FIELD
http://www.howequipmentworks.com/physics/medical_imaging/mri/magnetic_resonance_imaging.html
HYDROGEN IN A MAGNETIC FIELD
http://www.howequipmentworks.com/physics/medical_imaging/mri/magnetic_resonance_imaging.html
RF PULSE
http://www.howequipmentworks.com/physics/medical_imaging/mri/magnetic_resonance_imaging.html
RF PULSE
What will happen?
http://www.howequipmentworks.com/physics/medical_imaging/mri/magnetic_resonance_imaging.html
RF PULSE
http://www.howequipmentworks.com/physics/medical_imaging/mri/magnetic_resonance_imaging.html
RELAXATION
http://www.howequipmentworks.com/physics/medical_imaging/mri/magnetic_resonance_imaging.html
RELAXATION
For different tissues the time of relaxation
is different
http://www.howequipmentworks.com/physics/medical_imaging/mri/magnetic_resonance_imaging.html
NUCLEI SEND SIGNALS
One large piece is still missing…
GRADIENT COILS
http://www.howtolearn.com/HTL/media/Visualisations-in-Medicine-MRI-Hi-Res-Crop1.jpg
GRADIENT COILS
http://www.howtolearn.com/HTL/media/Visualisations-in-Medicine-MRI-Hi-Res-Crop1.jpg
GRADIENT COILS
http://www.howtolearn.com/HTL/media/Visualisations-in-Medicine-MRI-Hi-Res-Crop1.jpg
GRADIENT COILS
http://www.howtolearn.com/HTL/media/Visualisations-in-Medicine-MRI-Hi-Res-Crop1.jpg
GRADIENT COILS
http://www.howequipmentworks.com/physics/medical_imaging/mri/magnetic_resonance_imaging.html
GRADIENT COILS
http://www.howequipmentworks.com/physics/medical_imaging/mri/magnetic_resonance_imaging.html
GRADIENT COILS
http://www.howequipmentworks.com/physics/medical_imaging/mri/magnetic_resonance_imaging.html
GRADIENT COILS
http://www.howequipmentworks.com/physics/medical_imaging/mri/magnetic_resonance_imaging.html
GRADIENT COILS
http://www.howequipmentworks.com/physics/medical_imaging/mri/magnetic_resonance_imaging.html
GRADIENT COILS
http://www.howequipmentworks.com/physics/medical_imaging/mri/magnetic_resonance_imaging.html
FMRI F FOR FUNCTIONAL*
FMRI F FOR FUNCTIONAL*
*MRI signals associated with functional brain activity
BOLDBLOOD-OXYGEN-LEVEL DEPENDENT
Active neuron Passive neuron
I need oxygen and
glucose!I need nothing…
FMRI
Have different magnetic resonance
Distinguishable by MRI
FMRI DATA
• High spatial resolution !• No surgery! !• Records whole brain
SUMMARY
• Low temporal resolution !• Cost !• Size
Still pretty informative and precise, does not require a surgery, but is huge and costs a lot.
https://www.coursera.org/course/fmri
PART III EEG
http://infantlab.psych.sc.edu/PWREEGDemoBaby
NEURONS
http://biomedicalengineering.yolasite.com
NEURONS
http://www.conncad.com/gallery/single_cells.html
NEURONS
http://en.wikipedia.org/wiki/Neural_oscillation
NEURONS
http://en.wikipedia.org/wiki/Neural_oscillation
NEURONS
http://en.wikipedia.org/wiki/Neural_oscillation
NEURONS
http://en.wikipedia.org/wiki/Neural_oscillation
What is the frequency in this example?
BRAINWAVES
BRAINWAVESDelta 0-4 Hz
Theta 4-7 Hz
Alpha 7-14 Hz
Mu 8-13 Hz
Beta 15-30 Hz
Gamma 30-100 Hz
BRAINWAVESDelta 0-4 Hz
Theta 4-7 Hz
Alpha 7-14 Hz
Mu 8-13 Hz
Beta 15-30 Hz
Gamma 30-100 Hz
slow wave sleep, babies, lesions
children, drowsiness, meditation, relaxed
closed eyes, relaxed
motor neuron in rest, mirror neurons
motor activity, anxious thinking, concentration
networking between populations of neurons
EEG
EEG
EEG
TIME
CH
ANN
ELS
EEG
TIME
CH
ANN
ELS
EEG
Alpha 7-14 Hz
Beta 15-30 Hz
Gamma 30-100 Hz
?TIME
CH
ANN
ELS
EEG
Alpha 7-14 Hz
Beta 15-30 Hz
Gamma 30-100 Hz
?TIME
CH
ANN
ELS
Jean Baptiste Joseph Fourier 1768 — 1830
FOURIER TRANSFORM*
FOURIER TRANSFORM*
*discrete
FOURIER TRANSFORM*
*discrete
=
FOURIER TRANSFORM*
*discrete
signal at time t frequency complex number
=
FOURIER TRANSFORM*
*discrete
signal at time t frequency complex number
=
Amplitude of the component with
frequency k
FOURIER TRANSFORM*
*discrete
signal at time t frequency complex number
=
Amplitude of the component with
frequency k
EEG DATA
EEG DATA
EEG DATA
TIME-FREQUENCY DOMAIN
Are we done?
EEG DATA
Are we done?
Hint:
EEG DATA
300 MS
EEG DATA
300 MS
EEG DATA
300 MS
EEG DATA
300 MS
EEG DATA
300 MS
10 channels 50 frequencies 3 seconds of data 300 ms window
EEG DATA
300 MS
10 channels 50 frequencies 3 seconds of data 300 ms window
• How many numbers to describe 1 reading of 300 ms?
EEG DATA
300 MS
• How many numbers to describe 1 reading of 300 ms?
• How many numbers to describe all 3 seconds of data?
10 channels 50 frequencies 3 seconds of data 300 ms window
EEG DATA
• High temporal resolution !• No surgery! !• Mobile
!• Cheap
SUMMARY
• Low spatial resolution
Available to wide audience, but measurements are approximate.
SUMMARY OF NEUROIMAGING TECHNIQUESTechnology Electrical Magnetic Optical
Name EEG ECoG Intracortical MEG fMRI fNIRS
Invasive !
Portable !
Cost From $100 to $30,000+ $1000 grid
$2000 per array $1 mln $2-3
mln $200,000
Temporal resolution 50 ms 3 ms 3 ms 50ms 1-2 s 1 s
Spatial resolution 1+ cm 1 mm 0.5 mm -
0.05 mm 5 mm 1 mm voxels 5 mm
Pattern!classification VEP ERD/
ERS P300
Performance2 class 90% 3 class 80%
4 class ?
Large number
of targets2 cls 90%
Large number
of targets8 cls 90% High*
~ same as EEG based
4 cls 90%
2 cls 90%
Technology Electrical Magnetic Optical
Name EEG ECoG Intracortical MEG fMRI fNIRS
Invasive !
Portable !
Cost From $100 to $30,000+ $1000 grid
$2000 per array $1 mln $2-3
mln $200,000
Temporal resolution 50 ms 3 ms 3 ms 50ms 1-2 s 1 s
Spatial resolution 1+ cm 1 mm 0.5 mm -
0.05 mm 5 mm 1 mm voxels 5 mm
Pattern!classification VEP ERD/
ERS P300
Performance2 class 90% 3 class 80%
4 class ?
Large number
of targets2 cls 90%
Large number
of targets8 cls 90% High*
~ same as EEG based
4 cls 90%
2 cls 90%