Download - Evoked and Event-Related Potentials (ERP) Part 1 - Neurophysiological and Anatomical Basis
![Page 1: Evoked and Event-Related Potentials (ERP) Part 1 - Neurophysiological and Anatomical Basis](https://reader036.vdocuments.site/reader036/viewer/2022062517/56813a0c550346895da1de30/html5/thumbnails/1.jpg)
Evoked and Event-Related Potentials (ERP)Part 1 - Neurophysiological and Anatomical Basis
of Scalp-Recorded Activity
Craig E. Tenke & Jürgen Kayser
Division of Cognitive Neuroscience, New York State Psychiatric Institute, NY, NY
Department of Psychiatry, Columbia University College of Physicians & Surgeons, NY, NY
• towns (Geography: in southern France, Germany, Netherlands)• enterprise resource planning (Information Technology)• Ethernet Ring Protection (Information Technology)• erotic role-playing (Sexuality)• Economic Report of the President (Economics)• effective refractory period (Medicine: cardiac cycle)• Estonian Reform Party (Politics)• Electronic Road Pricing (Politics: toll-collection scheme in Singapore)• European Recovery Program (History: Marshall Plan)• European Radio Project (Communication: European Radio Network)• exposure and response prevention (Psychology: cognitive-behavioral treatment method)• event-related potential (Physics: an electrophysiological response to an internal or external stimulus)
Acronym ERP(wikipedia examples)
Event Related Potentials (ERP):Basics (Part 1)
27-Jan-2009
![Page 2: Evoked and Event-Related Potentials (ERP) Part 1 - Neurophysiological and Anatomical Basis](https://reader036.vdocuments.site/reader036/viewer/2022062517/56813a0c550346895da1de30/html5/thumbnails/2.jpg)
Outline
Part 1: Neurophysiological and Anatomical Basis of Scalp-Recorded Activityo Introduction: EEG measures synchronized neuronal activity (signal source)o The basic scientific method • Stimulation - Recording • Signal tracing/processing o Signal averaging: Evoked potentials (EPs) and event-related potentials (ERPs)• Theory of signal averaging• Animated examples• ERP applications• ERP topographies: Indicators of neuroanatomyo EEG biophysics• Volume Conduction and Ohm’s Law: Point generators• Vector formulation: A general model • Closed vs. open fieldso The cortical dipole: Direct evidence o A matter of scale: Micro- vs. macro- and intracranial vs. scalp electrodes
Part 2: Data acquisition and analysis: Conventions for scalp-recorded ERPs
o (details to be decided)
![Page 3: Evoked and Event-Related Potentials (ERP) Part 1 - Neurophysiological and Anatomical Basis](https://reader036.vdocuments.site/reader036/viewer/2022062517/56813a0c550346895da1de30/html5/thumbnails/3.jpg)
Part 1
Neurophysiological and Anatomical Basisof Scalp-Recorded Activity
Evoked and Event-Related Potentials (ERP)
![Page 4: Evoked and Event-Related Potentials (ERP) Part 1 - Neurophysiological and Anatomical Basis](https://reader036.vdocuments.site/reader036/viewer/2022062517/56813a0c550346895da1de30/html5/thumbnails/4.jpg)
What does EEG measure?
Changes in the extracellular potential corresponding to membrane polarization
![Page 5: Evoked and Event-Related Potentials (ERP) Part 1 - Neurophysiological and Anatomical Basis](https://reader036.vdocuments.site/reader036/viewer/2022062517/56813a0c550346895da1de30/html5/thumbnails/5.jpg)
Polarity reflects locationof cellular activity
Equivalent Current Dipolefrom apical EPSP
Equivalent Current Dipole from deep EPSP
![Page 6: Evoked and Event-Related Potentials (ERP) Part 1 - Neurophysiological and Anatomical Basis](https://reader036.vdocuments.site/reader036/viewer/2022062517/56813a0c550346895da1de30/html5/thumbnails/6.jpg)
Desynchronized PSP’s voltages cancel
“Closed Field” (No EEG at Scalp)
Importance of synchronized activity
![Page 7: Evoked and Event-Related Potentials (ERP) Part 1 - Neurophysiological and Anatomical Basis](https://reader036.vdocuments.site/reader036/viewer/2022062517/56813a0c550346895da1de30/html5/thumbnails/7.jpg)
Synchronized PSPs voltages add
“Open Field” (EEG at scalp)
Importance of synchronized activity
![Page 8: Evoked and Event-Related Potentials (ERP) Part 1 - Neurophysiological and Anatomical Basis](https://reader036.vdocuments.site/reader036/viewer/2022062517/56813a0c550346895da1de30/html5/thumbnails/8.jpg)
• when local neuronal activity is synchronized (time)
• when activity produces an open field (space)
• when activity at the recording site differs from the reference
Scalp-recorded EEG is measurable
![Page 9: Evoked and Event-Related Potentials (ERP) Part 1 - Neurophysiological and Anatomical Basis](https://reader036.vdocuments.site/reader036/viewer/2022062517/56813a0c550346895da1de30/html5/thumbnails/9.jpg)
Stimulation-Recording methods use timelocking
to synchronize activity
![Page 10: Evoked and Event-Related Potentials (ERP) Part 1 - Neurophysiological and Anatomical Basis](https://reader036.vdocuments.site/reader036/viewer/2022062517/56813a0c550346895da1de30/html5/thumbnails/10.jpg)
Stimulation-Recording Methods:Tracing signals through a “Black Box”
Signal Tracing:
Transit time:
Response Function:
To find System Properties
Compare Input Signal With Output Signal
e.g. synaptic delay across a sensory nucleus
Filtering and gain of output waveformNonlinear properties (e.g. flicker fusion)
Waveform latency, shape and topography e.g. cortical mapping
![Page 11: Evoked and Event-Related Potentials (ERP) Part 1 - Neurophysiological and Anatomical Basis](https://reader036.vdocuments.site/reader036/viewer/2022062517/56813a0c550346895da1de30/html5/thumbnails/11.jpg)
80 mm from stimulusThreshold Intensity Differential Threshold Differential Velocity
up is negative; right is reference
Mann 1997
Erlanger & Gasser
Compound Action Potential:A Stimulation-Recording Archetype
![Page 12: Evoked and Event-Related Potentials (ERP) Part 1 - Neurophysiological and Anatomical Basis](https://reader036.vdocuments.site/reader036/viewer/2022062517/56813a0c550346895da1de30/html5/thumbnails/12.jpg)
• time-locked electrical response of a neural system to an electrical or sensory signal
Averaged Evoked Potential
Evoked Potential (EP)
Schandry 1989
• average of time-locked EPs• EPs may vary considerably across
trials (averaging is generally necessary)
![Page 13: Evoked and Event-Related Potentials (ERP) Part 1 - Neurophysiological and Anatomical Basis](https://reader036.vdocuments.site/reader036/viewer/2022062517/56813a0c550346895da1de30/html5/thumbnails/13.jpg)
Examples of Averaged ERP
Auditory Oddball ERP(average)
Targets
Nontargets
Visual Hemifield ERP(average)
Kayser (2001) from Psychophysiology Lab website (http://psychophysiology.cpmc.columbia.edu)
![Page 14: Evoked and Event-Related Potentials (ERP) Part 1 - Neurophysiological and Anatomical Basis](https://reader036.vdocuments.site/reader036/viewer/2022062517/56813a0c550346895da1de30/html5/thumbnails/14.jpg)
• time-locked electrical response of a neural system to an electrical or sensory signal
Averaged Evoked Potential
Evoked Potential (EP)
Schandry 1989
• average of time-locked EPs• EPs may vary considerably across
trials (averaging is generally necessary)
Event-related Potential (ERP) • Generalized EP timelocked to a
stimulus, response, or informational event (e.g., missing stimulus in series of stimuli)
![Page 15: Evoked and Event-Related Potentials (ERP) Part 1 - Neurophysiological and Anatomical Basis](https://reader036.vdocuments.site/reader036/viewer/2022062517/56813a0c550346895da1de30/html5/thumbnails/15.jpg)
Applications of ERPs
1) Pathology:
3) Functional mapping:
Ramon y Cajal Mountcastle & Henneman(1952)
slowing or distortion of EP
parallel other neuroanatomical methods
2) Information processing(incl. perception, cognition)
![Page 16: Evoked and Event-Related Potentials (ERP) Part 1 - Neurophysiological and Anatomical Basis](https://reader036.vdocuments.site/reader036/viewer/2022062517/56813a0c550346895da1de30/html5/thumbnails/16.jpg)
ERP topographies have anatomical implications!
Topographies reflect macroscopic and microscopic anatomy
![Page 17: Evoked and Event-Related Potentials (ERP) Part 1 - Neurophysiological and Anatomical Basis](https://reader036.vdocuments.site/reader036/viewer/2022062517/56813a0c550346895da1de30/html5/thumbnails/17.jpg)
is directly proportional to
current I and inversely
related to distance (d)
EEG Biophysics:Volume Conduction and Ohm’s Law
Voltage Potential
V= I /R Voltage is directly proportional to current,and inversely related to resistance
For a point generator in a conductive medium, resistance is related to distance:
Tenke et al (1993))
![Page 18: Evoked and Event-Related Potentials (ERP) Part 1 - Neurophysiological and Anatomical Basis](https://reader036.vdocuments.site/reader036/viewer/2022062517/56813a0c550346895da1de30/html5/thumbnails/18.jpg)
4 electrodes
point source
As the generator becomes wider, the falloff becomes linear and shallow
EEG Biophysics:Volume Conduction implies Spatial Integration
![Page 19: Evoked and Event-Related Potentials (ERP) Part 1 - Neurophysiological and Anatomical Basis](https://reader036.vdocuments.site/reader036/viewer/2022062517/56813a0c550346895da1de30/html5/thumbnails/19.jpg)
EEG Biophysics:Complete Volume Conduction Model
Vector form of Ohm’s Law (proportionality of current flow and electric field vectors)
This fundamental relationship also underlies inverse models!Current Source Density (Im)
is a scalar
This is Poisson’s source equation relating current generators to voltage potentials
Tenke et al 1993
Problem: Neither current nor voltage are in this equation!
![Page 20: Evoked and Event-Related Potentials (ERP) Part 1 - Neurophysiological and Anatomical Basis](https://reader036.vdocuments.site/reader036/viewer/2022062517/56813a0c550346895da1de30/html5/thumbnails/20.jpg)
Simulated dipole laminae
50% inverted dipolesyield closed field
25% invertedyield open field
Field closure is quantitative,not qualitative
![Page 21: Evoked and Event-Related Potentials (ERP) Part 1 - Neurophysiological and Anatomical Basis](https://reader036.vdocuments.site/reader036/viewer/2022062517/56813a0c550346895da1de30/html5/thumbnails/21.jpg)
The Cortical Dipole
“Cortical Dipole” hypothesized from cortical projection cell asymmetry
Dep
th in
mm
(or
thog
onal
pe
netr
atio
n)
and supported superficial-to-deep polarity inversions
Intracortical profiles reveal complexity of processing
Within cortex field potential profiles reach maximum and invert in deeper layers
Tenke et al (unpublished))
![Page 22: Evoked and Event-Related Potentials (ERP) Part 1 - Neurophysiological and Anatomical Basis](https://reader036.vdocuments.site/reader036/viewer/2022062517/56813a0c550346895da1de30/html5/thumbnails/22.jpg)
A matter of scale:Intracranial recordings
ion channels,synaptic currents,
postsynaptic potentialsand unit discharges
(mV range)
Intracellular recordings
Extracellularrecordings
Local Field Potentials:postsynaptic potentials
and unit discharges
Selectivity for Local Activity!
Multicontact extracellularrecordings
Local Field Potentials:Summated PSPs, units
and multiunits•High-impedance electrodes•proximal to generators•far from external noise sources
![Page 23: Evoked and Event-Related Potentials (ERP) Part 1 - Neurophysiological and Anatomical Basis](https://reader036.vdocuments.site/reader036/viewer/2022062517/56813a0c550346895da1de30/html5/thumbnails/23.jpg)
A matter of scale:Surface and scalp recordings
Lower impedance electrodesLarger electrodes integrate over more tissueMore distant from generatorsFurther smearing by volume conduction
(smaller, composite signals)
Additional smearing(bone & skin)
Scalp recordings
Smaller amplitude compared to EOG, EKG etc. (uV range)
Proximity to EMG sources