setting up an meg and eeg experiment
TRANSCRIPT
Setting up an MEG and EEG experiment
Sheraz KHAN
Research Fellow
Athinoula A. Martinos Center for Biomedical Imaging
MGH/MIT/Harvard
Overview
Experimental Paradigms for MEG/EEG
Testing Experimental Paradigms
A typical MEG/EEG Visit
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Experimental Paradigms for MEG/EEG
-Inexpensive
-Portable
-Clinical
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Electricalencephalography (EEG)
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Experimental Paradigms for MEG/EEG
Not distorted by skull and scalp/ Simple modeling
Less preparation time/ Reference free
Best Results combing MEG with EEG (Wood et al,Science,85)
Khan & Cohen, 2013
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Magnetoencephalography (MEG)
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Experimental Paradigms for MEG/EEG
Upright Supine
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Experimental Paradigms for MEG/EEG
The high temporal resolution of MEG/EEG not only allow
us to follow sensory/cognitive events at millisecond
resolution but also decipher feedforward from feedback
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High temporal resolution
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Experimental Paradigms for MEG/EEG
block vs event related design
Block design Event related design
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The most common experimental
design is the interleaved
presentation of stimuli of various
categories and valences
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Experimental Paradigms for MEG/EEG
Clinical Applications
Dipole Localization
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MEG Sensor SpaceEEG Sensor Space
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Experimental Paradigms for MEG/EEG
Sleep studies
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MEG
Brain Rhythms
During sleep
Sleep Cycle
EEG
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Experimental Paradigms for MEG/EEG
Four basic stimulation systems
Auditory
Visual
Somatosensory
Olfactory
Auditory Visual
OlfactoryTactile-Somatosensory
Electrical-Somatosensory
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Experimental Paradigms for MEG/EEG
Auditory Experiment
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Cortical ResponsesTransfer function
Protocol
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Experimental Paradigms for MEG/EEG
Visual Experiments
Khan et al, PNAS ,201312/24/2015 Setting up an MEG and EEG Experiment
Protocol
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Experimental Paradigms for MEG/EEG
Electrical Mechanical
Tactile Khan et al, Frontiers Human Neuroscience ,2014
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Somatosensory Experiments
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Experimental Paradigms for MEG/EEG
Frequency-Tagging: When stimulus with specific
temporal encoding (e.g., visual pattern flickering at a well-
defined frequency) may trigger brain responses locked to
the stimulus presentation rate and its harmonics.
Khan et al, Brain ,2015
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Experimental Paradigms for MEG/EEG
Visual Tagging
Somatosensory Tagging Khan et al, Brain ,2015
Baldauf et al, Science ,2014
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Overview
Experimental Paradigms for MEG/EEG
Testing Experimental Paradigms
A typical MEG/EEG Visit
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Testing Experimental Paradigms
Adjusting Stimulus Parameters
Trial
Run
Stimulus Duration
Inter-Stimulus interval (ISI)
Inter-Stimulus Jitter (ISJ)
Stimulus Onset Asynchrony (SOA)
Stimulus Duration
ISI
ISJ
SOA
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Single Trial
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Testing Experimental Paradigms
Stimulus programming options
Open Source
Matlab based Psychophysics(psychtoolbox.org)
Python based PsychoPy (psychopy.org)
Commercial Packages
Presentation (neurobs.com)
Stim2 (compumedicsneuroscan.com)
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Testing Experimental Paradigms
Testing Timing, Jitter, Sound level, Brightness
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Photo Diode
Jitter
Protocol
Sound Meter
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Timing Accuracy
Averaging evoked fields
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Number of Trials
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Testing Experimental Paradigms
Testing Stimulus equipment for Artifact
Auditory
Tactile
Reponses Pad
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Testing Experimental Paradigms
Adjusting Hardware Setting
Sampling Rate
Filter Bandwidth
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Auditory Brainstem Responses
Working Memory
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Testing Experimental Paradigms
Behavioral Testing
Somatosensory priming
Valence Testing
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Testing Experimental Paradigms
Population Diversity
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Overview
Experimental Paradigms for MEG/EEG
Testing Experimental Paradigms
A typical MEG/EEG Visit
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A typical MEG/EEG Visit
A typical visit starts the day before, with a Call or email to
the subject to remind:
Sleep Well
Not to drink to much coffee or energy drink
No Makeup
Weight and if applicable eyeglasses prescription
Appropriate clothing
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A typical MEG/EEG Visit
Preparing EEG cap,
Extra electrodes
HPI and digitizer
Stimulus testing , Auditory gains, brightness, room light.
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Digitizer Head Position Indicator coilsEEG Cap
ElectrodesTrigger Box
Before the Subject arrives
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A typical MEG/EEG Visit
Tuning Channels
Acquire Empty room
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Tuner
Noise Co-variance matrix Acquisition software
Before the Subject arrives
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A typical MEG/EEG Visit
Prepare bedding
Prepare gowns
IRB/Consent forms
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Bedding
MEG/MRI compatible
Glasses
Scrubs
Before the Subject arrives
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A typical MEG/EEG Visit
After the Subject arrives
Consent forms
Explanation of protocols
Change to gown
Test Subject for Artifact
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Screening form
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A typical MEG/EEG Visit
Two Types of artifacts:
Biological
Blinks/secedes
Cardiac
Non Biological
Dental
Metal on body (internal/external)
Jewelry
Brain Stimulators
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Degaussers
Different artifacts
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A typical MEG/EEG Visit
Head digitization
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A typical MEG/EEG Visit
Position coils
Polhemus Data
Head digitization
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A typical MEG/EEG Visit
Electrode Placement
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A typical MEG/EEG Visit
Once you have placed the
subject in the MSR close the
MSR door
Use intercom; ask the subject
to relax
Check MEG signals
Once you start the acquisition
and at the beginning of each
run, you will be prompted to
record HPI
Once HPI measurement is ok,
you can start recording.
Continuously inspect the
quality of your data!
If individual bad channel
appears during the recording,
mark it as bad channel12/24/2015 Setting up an MEG and EEG Experiment
Intercom
During Experiment
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A typical MEG/EEG Visit
After Experiment Finishes
Tell subject you are opening the door
Remove HPIs and electrodes/EEG cap
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Subject coming out
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A typical MEG/EEG Visit
After the Subject leaves
Clean and disinfect the
electrodes/EEG Cap and the HPI
Clean the MEG helmet and chair.
Switch off the video projector
Switch off the light in the MSR
Log out of the acquisition computer
Take with you any leftover of your
presence (used papers,belts….)
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Wash Electrodes
Clean Countertops
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A typical MEG/EEG Visit
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Thank you
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Thank You
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Conflict of Interest Disclosure
Sheraz Khan
Advanced Imaging in Clinical/Translational Neuroscience
Research
April 13-15, 2015
I have no relevant financial
relationships with a commercial entity
producing healthcare-related products
and/or services.
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