Workshop: ERP Testing©

Dennis L. Molfese, Ph.D. University of Nebraska - Lincoln

DOE 993511 NIH R01 HL0100602 NIH R01 DC005994 NIH R41 HD47083 NIH R01 DA017863 NASA SA42-05-018 NASA SA23-06-015

Friday, January 14, 2011 Workshop Goals

Concepts & Definitions

Friday, January 14, 2011 Workshop Goals

Concepts & Definitions Common Practices

Friday, January 14, 2011 Workshop Goals

Concepts & Definitions Common Practices Analysis Approaches

Friday, January 14, 2011 Workshop Goals

Concepts & Definitions Common Practices Analysis Approaches Dealing with Artifacts

Friday, January 14, 2011 Workshop Goals

Concepts & Definitions Common Practices Analysis Approaches Dealing with Artifacts Problem Solving

Friday, January 14, 2011 Friday, January 14, 2011 Workshop Daily Schedule Day 1 ERP Theory, Methodology, Issues Electrode issues Artifacts Equipment Videos - Unpack & Setup ERP System Electrode Net Application Net Station Operation

Friday, January 14, 2011 Workshop Daily Schedule Day 2

Preprocessing of ERP Data Data Management & Analyses Videos - Packing up ERP System

Friday, January 14, 2011 Ultimate Goal

You Become An Independent Neuroscience Investigator who can: 1. Design & conduct independent studies. 2. Develop the Skills to run data analyses. 3. Draft and submit imaging manuscripts. 4. Develop grant applications. 5. Revolutionize your major field of study.

Friday, January 14, 2011 The Training Plan

1. Two-day ERP workshop 2. Experiment planning session(s) 3. Hands-on training on ERP equipment 4. Conducting YOUR experiment 5. Data Analysis Assistance 6. Manuscript Development Assistance 7. Grant Application Assistance

Friday, January 14, 2011 1.Overview of ERP Theory, Methodology & Issues.

Why ERPs?

Correlation with cognitive & physiological events Time resolution (ms) Spatial resolution Portability No age limits Useful with or without behavioral response Cost 8

Friday, January 14, 2011 General Methodology Principles

Same as in any research:

Friday, January 14, 2011 General Methodology Principles

Same as in any research: Screen & control participant variables

Friday, January 14, 2011 General Methodology Principles

Same as in any research: Screen & control participant variables Control stimulus & experimental factors

Friday, January 14, 2011 General Methodology Principles

Same as in any research: Screen & control participant variables Control stimulus & experimental factors Data quality

Friday, January 14, 2011 General Methodology Principles

Same as in any research: Screen & control participant variables Control stimulus & experimental factors Data quality Database

Friday, January 14, 2011 General Methodology Principles

Same as in any research: Screen & control participant variables Control stimulus & experimental factors Data quality Database Data analyses

Friday, January 14, 2011 General Methodology Principles

Same as in any research: Screen & control participant variables Control stimulus & experimental factors Data quality Database Data analyses Replication

Friday, January 14, 2011 ERPs

History Definitions Electrodes Testing Issues Applications

Friday, January 14, 2011 Where we have come from....

1890s

Friday, January 14, 2011 Where we have come from....

1950s

Friday, January 14, 2011 Where we have come from....

Oscilloscope Tracings & Photographs

Friday, January 14, 2011 Where we have come from....

1970s

Friday, January 14, 2011 Where are we now....

Friday, January 14, 2011 ERPs to CVC Words

Below Average Readers Average Readers Above Average Readers

Friday, January 14, 2011 Event-Related Potentials

ERP

Friday, January 14, 2011 Event-Related Potentials

ERP Portion of Ongoing EEG

Friday, January 14, 2011 Event-Related Potentials

ERP Portion of Ongoing EEG Time-Locked to Stimulus Onset

Friday, January 14, 2011 Event-Related Potentials

ERP Portion of Ongoing EEG Time-Locked to Stimulus Onset Temporal Information

Friday, January 14, 2011 Event-Related Potentials

ERP Portion of Ongoing EEG Time-Locked to Stimulus Onset Temporal Information Spatial Information

Friday, January 14, 2011 Event-Related Potentials

ERP Portion of Ongoing EEG Time-Locked to Stimulus Onset Temporal Information Spatial Information Comparability across the lifespan

Friday, January 14, 2011 EEG Activity

Friday, January 14, 2011 Friday, January 14, 2011 Sampling (Digitizing) Rates

Friday, January 14, 2011 Sampling (Digitizing) Rates

 Brain Stem Evoked Response (BSER) 1 - 15 ms

Friday, January 14, 2011 Sampling (Digitizing) Rates

 Brain Stem Evoked Response (BSER) 1 - 15 ms  Peak Duration 1 - 1.5 ms

Friday, January 14, 2011 Sampling (Digitizing) Rates

 Brain Stem Evoked Response (BSER) 1 - 15 ms  Peak Duration 1 - 1.5 ms  5-7 peaks to resolve

Friday, January 14, 2011 Sampling (Digitizing) Rates

 Brain Stem Evoked Response (BSER) 1 - 15 ms  Peak Duration 1 - 1.5 ms  5-7 peaks to resolve  Sample 1/5 - 1/10 ms

Friday, January 14, 2011 Sampling (Digitizing) Rates

 Brain Stem Evoked Response (BSER) 1 - 15 ms  Peak Duration 1 - 1.5 ms  5-7 peaks to resolve  Sample 1/5 - 1/10 ms  Middle Latency Response 15 - 65 ms

Friday, January 14, 2011 Sampling (Digitizing) Rates

 Brain Stem Evoked Response (BSER) 1 - 15 ms  Peak Duration 1 - 1.5 ms  5-7 peaks to resolve  Sample 1/5 - 1/10 ms  Middle Latency Response 15 - 65 ms  Peak Duration 3 - 5 ms

Friday, January 14, 2011 Sampling (Digitizing) Rates

 Brain Stem Evoked Response (BSER) 1 - 15 ms  Peak Duration 1 - 1.5 ms  5-7 peaks to resolve  Sample 1/5 - 1/10 ms  Middle Latency Response 15 - 65 ms  Peak Duration 3 - 5 ms  Sample 1/2 - 1 ms  Cognitive components 65 - 1000 ms  Peak Duration 20 - 100 ms

Friday, January 14, 2011 Sampling (Digitizing) Rates

Friday, January 14, 2011 ERPs - Extracellular

Friday, January 14, 2011 Event Related Potentials (ERPs)

Time-locked to an evoking or eliciting event or stimulus.

Friday, January 14, 2011 Event Related Potentials (ERPs)

Time-locked to an evoking or eliciting event or stimulus. Sequence of serially activated "processes" (components) detected at the scalp (or some biological surface) as distinct positive- negative ﬂuctuations.

Friday, January 14, 2011 Event Related Potentials (ERPs)

Measures:

Friday, January 14, 2011 Event Related Potentials (ERPs)

Measures: !(1) peak latency from evoking stimulus onset (ms)

Friday, January 14, 2011 Event Related Potentials (ERPs)

Measures: !(1) peak latency from evoking stimulus onset (ms) !(2) peak amplitude in microvolts µV

Friday, January 14, 2011 Event Related Potentials (ERPs)

Measures: !(1) peak latency from evoking stimulus onset (ms) !(2) peak amplitude in microvolts µV (3) polarity (deﬂection from baseline to + or -)

Friday, January 14, 2011 Definitions for ERP displays

 x-axis  horizontal  abscicca  time - ms  y-axis  vertical  ordinate  voltage amplitude - µV

Friday, January 14, 2011 ERP Nomenclature

P2 P3 P4 P1 N2 N1 N3

Friday, January 14, 2011 ERP Nomenclature

After Desmedt, 1974

Friday, January 14, 2011 Display Positive vs. Negative Up

Arbitrary

Friday, January 14, 2011 Display Positive vs. Negative Up

Arbitrary Tradition: 70% show Negative Up

Friday, January 14, 2011 Display Positive vs. Negative Up

Arbitrary Tradition: 70% show Negative Up

Friday, January 14, 2011 Display Positive vs. Negative Up

Arbitrary Tradition: 70% show Negative Up

Creates some confusion in comparing work across studies

Friday, January 14, 2011 Display Positive vs. Negative Up

Arbitrary Tradition: 70% show Negative Up

Creates some confusion in comparing work across studies

Friday, January 14, 2011 Display Positive vs. Negative Up

Arbitrary Tradition: 70% show Negative Up

Creates some confusion in comparing work across studies

Good to practice inverting waves to gain rapid visual recognition of peaks

Friday, January 14, 2011 Display Positive vs. Negative Up

Positive Up Negative Up

+ -

Friday, January 14, 2011 Display Positive Up

.3 - 100 Hz 60 Hz Notch

Friday, January 14, 2011 Display Positive Down

.3 - 100 Hz 60 Hz Notch

Friday, January 14, 2011 Variations in ERPs Trial by Trial

Variations in Amplitude & Latency

Note amplitude

500 ms ALPHA

10 trials selected every 10 trials across 100 trials

Friday, January 14, 2011 Peak Latency Variations Produce Different Width Peaks Peak Amplitude Variations Produce Different Size Peaks

More Latency Shift Less Latency Shift

Friday, January 14, 2011 ERP Temporal - Spatial Dynamics

Assess effects that differ in:

Friday, January 14, 2011 ERP Temporal - Spatial Dynamics

Assess effects that differ in:

Friday, January 14, 2011 ERP Temporal - Spatial Dynamics

Assess effects that differ in:

•Time (ms)

Friday, January 14, 2011 ERP Temporal - Spatial Dynamics

Assess effects that differ in:

•Time (ms) •Scalp region distribution (2-D scalp surface space)

Friday, January 14, 2011 ERP Temporal - Spatial Dynamics

Assess effects that differ in:

•Time (ms) •Scalp region distribution (2-D scalp surface space) •Dipole effects (Time and 3-D space)

Friday, January 14, 2011 Basic Measurements

 Amplitude  Peak amplitude (maximum/minimum point)  Mean peak amplitude (average # of points)  Latency  Peak latency (maximum/minimum point)  Mean peak latency (average # of time points)  Area (Under the Curve)  Area for specific region

Friday, January 14, 2011 ERP Amplitude & Latency Measures

Friday, January 14, 2011 Basic Measurements

 Amplitude  Peak amplitude  (maximum/minimum point)

 Mean peak amplitude  (average # of points)

Friday, January 14, 2011 Basic Measurements

 Latency  Peak latency  (maximum/minimum point)

 Mean peak latency  (average # of time points)

Friday, January 14, 2011 Basic Measurements

 Area (Under the Curve)  Area for specific region a b c c  50% area (midpoint) 50%

Friday, January 14, 2011 Peak & Latency Analysis

Pros:  Traditional approach  Appears straight forward & logical Cons: - Peaks are not always clear - Developmental issues (changes in latency & amplitude) - Latency shift across scalp & subjects - Subjective judgments - Variations in criteria across journal reports - Very time consuming in training & execution - Replication problems within/across labs - Inter-rater reliability (typically not conducted/reported)

Friday, January 14, 2011 Peak & Latency Analysis

Friday, January 14, 2011 Sample Neonate Responses

Friday, January 14, 2011 ERPs & Averaging

S/N = Signal-to-Noise-Ratio

Individual (single trial) ERPs are VERY small - depends on age (e.g., ~.5 to 30µV) Ampliﬁer/environmental noise are large - varies across amps & manufacturers and models - ~10 µV RMS (same size to 20x larger than single trial ERP)

Thus, single trial ERPs can be OBSCURED by large electrical events, i.e., ampliﬁer noise, environmental signals, artifacts

TO SOLVE PROBLEM: Repeat same stimulus & average resultant single trial ERPs together to increase S/N ratio to improve ERP (signal) quality. 42

Friday, January 14, 2011 ERPs & Averaging

Goff, 1971 43

Friday, January 14, 2011 ERPs & Averaging

ERP noise level varies with number of trials to create the average - square root “law” (conservative) - noise level = square root of the number of trials: 9 trials = 32 or 33.33% of signal could be noise 16 trials = 42 or 25.00% of signal could be noise 25 trials = 52 or 20.00% of signal could be noise 36 trials = 62 or 16.67% of signal could be noise 49 trials = 72 or 14.29% of signal could be noise 64 trials = 82 or 12.50% of signal could be noise 81 trials = 92 or 11.11% of signal could be noise 100 trials = 102 or 10.00% of signal could be noise 44

Friday, January 14, 2011 ERPs & Averaging

Relation of Trials to Signal Noise

120

100 # Trials per Average

Number of TrialsNumber in Average % of ERP that is Noise 0 1 2 3 4 5 6 7 8 ERP Signal Improvement

Trade-off between improving S/N and completing an experiment. 45

Friday, January 14, 2011 Average ERP obtained early during test differs from later in the same test period.

First 25 Trails Trial #s combined Reference = to make average linked mastoids ERP

Last 25 Trails

Friday, January 14, 2011 ERPs & Averaging

The MORE trials presented, the better the S/N ratio.

The MORE trials presented, the LONGER the test session.

The LONGER the test session, the LESS LIKELY the infant/ child will complete session.

The LONGER the test session, the LESS LIKELY later ERPs will resemble earlier trial ERPs.

The REAL key to testing populations is to obtain the best S/N ratio without overtaxing the subject (e.g., infant, child, adult).

Friday, January 14, 2011 Another Way To Look At ERPs

“ba”

Friday, January 14, 2011 Yellow Increasing Red Positive Purple Voltage Dark Blue

Increasing Negative Voltage

Friday, January 14, 2011 Neonate ERP to Speech Syllable

Yellow

Red

Purple

Dark Blue

Friday, January 14, 2011 Adult ERP to Speech Syllable

Yellow

Red

Purple

Dark Blue

Friday, January 14, 2011 QUESTIONS ???

Friday, January 14, 2011 Dipoles

a) Dipole used as description of ERP generation.

Friday, January 14, 2011 Dipoles

a) Dipole used as description of ERP generation.

Friday, January 14, 2011 Dipoles

a) Dipole used as description of ERP generation.

b) Dipoles perpendicular to surface (since cortex folds, not necessarily perpendicular

Friday, January 14, 2011 Dipoles

a) Dipole used as description of ERP generation.

b) Dipoles perpendicular to surface (since cortex folds, not necessarily perpendicular to scalp surface).

Friday, January 14, 2011 Dipoles

a) Dipole used as description of ERP generation.

b) Dipoles perpendicular to surface (since cortex folds, not necessarily perpendicular to scalp surface).

Friday, January 14, 2011 Dipoles

a) Dipole used as description of ERP generation.

b) Dipoles perpendicular to surface (since cortex folds, not necessarily perpendicular to scalp surface).

c) Reflects differences in soma and dendrite ion flow across cortical layers.

Friday, January 14, 2011 Dipoles

d) Model activity.

Friday, January 14, 2011 Dipoles

d) Model activity.

Friday, January 14, 2011 Dipoles

d) Model activity.

e) Activity at scalp not necessarily result of ion movements immediately below electrode.

Friday, January 14, 2011 Dipoles

d) Model activity.

e) Activity at scalp not necessarily result of ion movements immediately below electrode.

Friday, January 14, 2011 Dipoles

d) Model activity.

e) Activity at scalp not necessarily result of ion movements immediately below electrode.

f) Caution: Dipoles generated in one hemisphere may generate higher shifts in other hemisphere.

Friday, January 14, 2011 0.400

0.200 Low GRTR Scores 0 -0.200

-0.400

1-dipole Model 200 ms -0.600

-0.800

-1.000

-1.200

-1.400 Match Mismatch -1.600 0 36 72 108 144 180 216 252 288 324 360 396 432 468 504 540 576 612 648 684

Friday, January 14, 2011 0.400

0.200 High GRTR Scores 0 -0.200

-0.400

2-dipole Model 200 ms -0.600

-0.800

-1.000

-1.200

-1.400 Match Mismatch -1.600 0 36 72 108 144 180 216 252 288 324 360 396 432 468 504 540 576 612 648 684

Friday, January 14, 2011 Are Dipoles “Real” ? SENSE

3/1/01 5/2/01

Left Hand Right Hand Left Hand Right Hand

Friday, January 14, 2011 QUESTIONS ???

Lantz, G., Grave de Peralta, R., Spinelli, L., Seeck, M., & Michel, C. M. (2003). Epileptic source localization with high density EEG: How many electrodes are needed? Clinical Neurophysiology, 114, 63-69. Michel, C. M., Lantz, G., Spinelli, L., Grave de Peralta Menendez, R., Landis, T., & Seeck, M. (2004a). 128-channel EEG source imaging in epilepsy: Clinical yield and localization precision. Journal of Clinical Neurophysiology. Michel, C. M., Murray, M. M., Lantz, G., Gonzalez, S., Spinelli, L., & Grave de Peralta, R. (2004b). EEG source imaging. Clinical Neurophysiology, 115, 2195-2222. Tucker, D. M., Luu, P., Frishkoff, G., Quiring, J. M., & Poulsen, K. (2003). Corticolimbic response to negative feedback in clinical depression. Journal of Abnormal Psychology, 112, 667-678. 58

Friday, January 14, 2011 Digitizing Rate

 How fast to sample the ERP signal?  Convention = 250 Hz (4 ms intervals)  Ultimately dependent on signal characteristics

Friday, January 14, 2011 Nyquist's theorem: Analog waveform may be uniquely reconstructed, without error, from samples taken at equal time intervals. Sampling rate must be equal to, or greater than, twice the highest frequency component in the analog signal (3x works better).

Example: 9 Hz wave sampled 9 times/Sec = 1 Hz waveform

Friday, January 14, 2011 Nyquist - 9 Hz signal

Sampled Sampled at 29 Hz at 14 Hz

Yields 9 Yields 4.5 Hz Signal Hz Signal

Alias - appear as more energy (higher amplitude) at lower frequency

Friday, January 14, 2011 Nyquist - Signal is sum of Sinusoidal Frequencies of 6.5, 10, 19 Hz

Srinivasan, Tucker & Murias, 1985

Friday, January 14, 2011 How Many Electrodes Should You Use ?

Depends on : Research Question. Availability of Equipment.

Source Localization AND Scalp Distribution Studies ALWAYS require LARGE number of Electrodes adults = 256 infants = 128

Friday, January 14, 2011 Resolution of Scalp Signals

Simulation of Infant & Child Scalp ERP Signals.

Simulation of Adult Scalp ERP Signals.

Friday, January 14, 2011 If spatial sampling is too sparse, high spatial details will alias into low spatial frequencies, distorting topographic maps & source localization !

7 cm

Srinivasan, Tucker & Murias, 1985

Friday, January 14, 2011 Nyquist

The smallest topographic feature that can be resolved accurately by a 32-channel array is 7 cm in diameter - about the size of an ENTIRE lobe of the brain !!!

Friday, January 14, 2011 QUESTIONS ???

Friday, January 14, 2011 Impedance

 Before lab computers  EEG quality depended on paper recorded signal.

 Noise from power lines (50 or 60 Hz) difﬁcult to separate once introduced,

 Procedure involved abrading skin to achieve a scalp-electrode impedance < 5 kilo Ohms.

 Abrasion removes surface epidermal layer that has greater impedance than underlying tissue.

Friday, January 14, 2011 Impedance

http://www.sengpielaudio.com/calculator-ohmslaw.htm

Friday, January 14, 2011 Impedance

Voltage (V) = Current(I) X Resistance(R)

If Resistance increases, Current ﬂow will decrease: V/R = I If Voltage increases, Current ﬂow increases: V = C x R

Current measured in Amps Voltage measured in Volts Resistance measured in Ohms

Plumbing Analogy: Voltage ~ Water pressure (in a tank) Current ~ Flow Rate (from the tank) Resistance ~ pipe size (allowing water to escape from tank)

Friday, January 14, 2011 Impedance

 High vs. Low Impedance Amplifiers

Friday, January 14, 2011 Impedance

 High vs. Low Impedance Amplifiers  (elec) vs. (amp)  High vs. High: 5x10-10  .00000000005  Low vs. Low: 5x10-9  .0000000005

Practice electric circuits: http://www.phy.hk/wiki/englishhtm/Circuit.htm

Friday, January 14, 2011 Impedance

Ferree, T., Luu, P., Russel, J. S., & Tucker, D. M. (2001). Scalp electrode impedance, infection risk, and EEG data quality. Clinical Neurophysiology, 112, 536-544.

Note: Watts = Amps x Volts

Friday, January 14, 2011 Electrode Paste vs. Collodian

 Adhesive paste EC2 vs. collodion for long-term scalp electrodes placement  40 patients  20: electrode placement on scalp with collodion - Group C (ollodian)  20: EC2 used - Group P(aste).  impedance of electrodes measured after electrode placement (T1) and after 24 h of recording (T2),  Application time calculated for all patients

 RESULTS: At each observation, group C showed mean values of electrode impedance significantly higher than group P  Collodion: T1: 16.8 kohm; T2: 6.5 kohm  EC2 Paste: T1: 2.4 kohm; T2: 4.0 kohm, p < 1 x 10(-5).

Friday, January 14, 2011 Electrode Paste vs. Collodian

 Time required to make montage and provide daily maintenance was significantly shorter in group P than in group C  Collodion: 44.3 and 19.7 min  EC2 Paste: 20.8 and 10.5 min, p < 1 x 10(-5).

 CONCLUSIONS: EC2 paste attaches scalp electrode in less time,  with better recording quality as a result of lower electrode impedance values, than collodion.

 SIGNIFICANCE: EC2 paste can substitute for collodion in electrode placement for long-term video-EEG monitoring, with an optimal cost-benefit ratio in terms of recording performance, time consumption, & safety.

Friday, January 14, 2011 QUESTIONS ???

Friday, January 14, 2011 Filters

 ERPs (and EEG) are electrical signals that vary in their frequencies and amplitude.

Friday, January 14, 2011 Filters

 ERPs (and EEG) are electrical signals that vary in their frequencies and amplitude.  Filter determines the way in which ampliﬁer sensitivity changes as frequency is reduced.

Friday, January 14, 2011 Filters

 ERPs (and EEG) are electrical signals that vary in their frequencies and amplitude.  Filter determines the way in which amplifier sensitivity changes as frequency is reduced.  Frequency response - bandwidth of amplifier determined by its high & low frequency filters.

Friday, January 14, 2011 Filters

 D.C. Ampliﬁer

Friday, January 14, 2011 Filters

 D.C. Ampliﬁer  Sensitivity does not change with decreasing frequency.

Friday, January 14, 2011 Filters

 D.C. Ampliﬁer  Sensitivity does not change with decreasing frequency.

Friday, January 14, 2011 Filters

 D.C. Ampliﬁer  Sensitivity does not change with decreasing frequency.

 Subject to very slow change of output level (drift).

Friday, January 14, 2011 Filters

 Low Pass Filter - attenuates HIGH frequency while “saving” or passing through the LOW frequencies (high frequency ﬁlter, high band pass ﬁlter)

Friday, January 14, 2011 Filters

 Low Pass Filter - attenuates HIGH frequency while “saving” or passing through the LOW frequencies (high frequency ﬁlter, high band pass ﬁlter)

Friday, January 14, 2011 Filters

 Low Pass Filter - attenuates HIGH frequency while “saving” or passing through the LOW frequencies (high frequency ﬁlter, high band pass ﬁlter)

 High Pass Filter - attenuates LOW frequency while “saving” or passing through the HIGH frequencies (low frequency ﬁlter, low band pass ﬁlter)

Friday, January 14, 2011 Amplifier Filter Settings

 Signals are reduced 50% already when frequency reaches setting depicted on most amplifiers.

Friday, January 14, 2011 Amplifier Filter Settings

 Signals are reduced 50% already when frequency reaches setting depicted on most amplifiers.  Referred to as “Half-Amplitudes”

Friday, January 14, 2011 Amplifier Filter Settings

 Signals are reduced 50% already when frequency reaches setting depicted on most amplifiers.  Referred to as “Half-Amplitudes”  E.G., Setting on an amplifier of 2Hz and 30Hz means signal already reduced by 50% at filter boundaries.

Friday, January 14, 2011 Filters

 Filtering - sometimes represented as a Time Constant (TC)

Friday, January 14, 2011 Filters

 Filtering - sometimes represented as a Time Constant (TC)

Friday, January 14, 2011 Filters

 Filtering - sometimes represented as a Time Constant (TC)

 Describes how ampliﬁer responds to a voltage change

Friday, January 14, 2011 Filters

 Voltage -> ampliﬁer is changed.

Friday, January 14, 2011 Filters

 Voltage -> amplifier is changed.  Amplifier output changed but gradually returns to baseline, producing a curve (exponential curve) that approaches its final value at a decreasing rate.

Friday, January 14, 2011 Filters

 Voltage -> amplifier is changed.  Amplifier output changed but gradually returns to baseline, producing a curve (exponential curve) that approaches its final value at a decreasing rate.  This curve has time constant (the time it takes for the AMPLITUDE to FALL to 37% of its INITIAL VALUE).

Friday, January 14, 2011 Filters

 As TIME CONSTANT (TC) increases, high pass filter frequency decreases (memorize ***)

Friday, January 14, 2011 Filters

 TIME CONSTANT = C  Frequency = f  Pi = 3.1415  1/(2 x Pi x C) = f  0.159/C = f  0.159/0.3 = 0.5 Hz (cut off point of low- frequency.)

 TC = 0.1, low frequency passed = 1.59 Hz  TC = 0.5, low frequency passed = 0.318 Hz  TC = 1.0, low frequency passed = 0.159 Hz

Friday, January 14, 2011 Filters: ERP amplitude and latency WILL change when applying different filters.

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Friday,!"#$% January 14, 2011 Filters: ERP amplitude and latency WILL change when applying different filters.

High Pass Filter Low Pass Filter

NOTE: Filters do NOT cut off the signal at ﬁlter settings ! Friday, January 14, 2011 Filters .3 - 100 Hz



Friday, January 14, 2011 Filters - .3 - 30 Hz (60 Hz notch filter)



Friday, January 14, 2011 Filters - .3 - 30 Hz

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Friday, January 14, 2011 Note: 60 Hz filter has no effect on ERP waveform if LOW PASS = 30 Hz

Friday, January 14, 2011 Filters

As LOW PASS ﬁlter setting DECREASES, Peak Latencies will INCREASE (occur later) and slower frequencies will become more prominent in the ERP waveform as higher frequencies are ﬁltered out (excluded).

aka: Peak Latencies will occur later in the ERP waveform.

Friday, January 14, 2011 Filters .3 - 100 Hz

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Friday, January 14, 2011 Filters - .3 - 30 Hz

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Friday, January 14, 2011 Filters - 0.3 - 10 Hz

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Friday, January 14, 2011 Filters - .3 - 5.0 Hz



Friday, January 14, 2011 Filters

As LOW PASS ﬁlter setting INCREASES, Peak Latencies will DECREASE and higher (faster) frequencies will become more prominent in the ERP waveform as higher frequencies are included (not ﬁltered out).

aka: Peak Latencies will occur EARLIER in the ERP waveform.

Friday, January 14, 2011 Filters - 2.0 - 10 Hz

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Friday, January 14, 2011 Filters - 2.0 - 20 Hz



Lower Low Pass gives Longer Latencies !!!

Friday, January 14, 2011 Filters - 2.0 - 30 Hz

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Friday, January 14, 2011 Filters - 2.0 - 100 Hz (60 Hz notch filter)



Friday, January 14, 2011 Filters

As HIGH PASS ﬁlter setting INCREASES, Peak Latencies will DECREASE and higher (faster) frequencies will become more prominent in the ERP waveform as lower frequencies are excluded (ﬁltered out).

Amplitudes will appear to decrease (get smaller).

aka: Peak Latencies will occur EARLIER in the ERP waveform. aka: Peak Amplitudes will decrease in size.

102

Friday, January 14, 2011 Filters - 2.0 - 100 Hz (60 Hz notch filter)



Friday, January 14, 2011 Filters - 3.0 - 100 Hz (60 Hz notch filter)

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Friday, January 14, 2011 Filters - 5.0 - 100 Hz (60 Hz notch filter)



Friday, January 14, 2011 Filters - signals change with filtering

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Friday, January 14, 2011 Filters: Topography 2.0 - 100 Hz (60hz)

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Friday, January 14, 2011 Filters: Topography .3 - 100 Hz

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Friday, January 14, 2011 Filters: Topography .3 - 30 Hz

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Friday, January 14, 2011 Filters: Topography .3 - 10 Hz

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Friday, January 14, 2011 Filters: Topography .3 - 5 Hz

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Friday, January 14, 2011 Filters: Topography 5.0 - 10 Hz

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Friday, January 14, 2011 Filters: Topography 5.0 - 15 Hz

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Friday, January 14, 2011 Filters: Topography 5.0 - 100 Hz (60hz)

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Friday, January 14, 2011 Filters: Topography 10 - 100 Hz (60hz)

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Friday, January 14, 2011 Filters: Topography 10 - 30 Hz

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Friday, January 14, 2011 Take Home Memory

 Different Filters produce different ERP waveforms  Latency shifts  Amplitude variations (positive & negative peaks)  Slope changes  Component structure impacted

117

Friday, January 14, 2011 CRITICAL

When reading the literature ALWAYS pay strict attention to filter settings and gain settings used by investigators.

DIFFERENT RESULTS with DIFFERENT FILTERS and GAIN (amplitude) settings.

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Friday, January 14, 2011 QUESTION

 If 2 ERPs are collected but with different filter settings, which is the REAL data?

 Will the REAL ERP please stand up!

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Friday, January 14, 2011 QUESTIONS ???

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Friday, January 14, 2011 Adult Peak Components

 ERPs usually described in terms of  Peaks (positive or negative)  Latency (post stimulus onset)  Duration (e.g., slow wave)  Scalp topography (maximal peak location)  Source (location within the brain)

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Friday, January 14, 2011 Scalp Volume Conduction

 Current flow across the scalp  Produces latency shifts from one part of scalp to another  Also produces amplitude shifts across scalp  Signals sum across the scalp  large positive wave on scalp meeting large negative wave could sum to flat line!

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Friday, January 14, 2011 EXPERIMENTAL DESIGN ISSUES: Types of Experiments

Friday, January 14, 2011 EXPERIMENTAL DESIGN ISSUES: Types of Experiments  Common approaches

Friday, January 14, 2011 EXPERIMENTAL DESIGN ISSUES: Types of Experiments  Common approaches  Odd-ball tasks (P3 or P300)

Friday, January 14, 2011 EXPERIMENTAL DESIGN ISSUES: Types of Experiments  Common approaches  Odd-ball tasks (P3 or P300)  Sentence completion (N400)

Friday, January 14, 2011 EXPERIMENTAL DESIGN ISSUES: Types of Experiments  Common approaches  Odd-ball tasks (P3 or P300)  Sentence completion (N400)  Mismatch negativity (MMN)

Friday, January 14, 2011 EXPERIMENTAL DESIGN ISSUES: Types of Experiments  Common approaches  Odd-ball tasks (P3 or P300)  Sentence completion (N400)  Mismatch negativity (MMN)  Error-related negativity (ERN)  Feedback-Related Negativity (FRN)

Friday, January 14, 2011 Adult Peak Components: Some Descriptions

P1 or P50 (auditory)

Friday, January 14, 2011 Adult Peak Components: Some Descriptions

P1 or P50 (auditory) - Not always present

- Occurs earlier over posterior than anterior scalp electrode sites

- Larger amplitudes over frontal and/or central regions

Friday, January 14, 2011 Adult Peak Components

P1 or P50 (auditory) - Distribution symmetrical over both hemispheres except for anterior temporal regions where larger amplitudes occur over left hemisphere;

-Overall, peak amplitude and latency decrease with age to the point where the peak disappears (Coch, et al., 2002).

Friday, January 14, 2011 Adult Peak Components P1 or P50 (auditory) - Frequently associated with auditory inhibition in sensory gating paradigm where paired clicks presented at short ISIs.

Amplitude of averaged ERP to second of paired clicks is typically reduced compared to averaged response to the first click.

Magnitude of suppression commonly interpreted as neurophysiological index of sensory gating.

Friday, January 14, 2011 Adult Peak Components

P1 or P50 (auditory)

- Reduced suppression frequently reported for schizophrenic patients.

- In some neuropsychiatric disorders (schizophrenia, mania), peak amplitude to paired stimuli approximately equal.

- P1 latency clinically used to diagnose neurodegenerative diseases (multiple sclerosis, Parkinson’s Disease).

Friday, January 14, 2011 Adult Peak Components P1 or P50 (auditory)

- Buchwald et al. (1992) proposed that P50 response associated with ascending reticular activating system (RAS) and its post-synaptic thalamic targets.

- Thoma et al. (2003) and Huotilainen (1998) independently localized sources of P50 in superior temporal gyrus using MEG approach.

-Weisser et al (2001) co-registered auditory evoked potentials & magnetic fields (AEFs). The resulting equivalent dipole model for ERPs consisted of one source in auditory cortex of each hemisphere and a radially oriented medial frontal source.

Friday, January 14, 2011 Adult Peak Components P1 or P50 (visual) - Visual P1 differs from auditory P1 in terms of evoking stimulus, neurocognitive and neurophysiological mechanism, peak latency, scalp distribution, neural sources.

- Visual P1 typically recorded in a checkerboard- reversal task or similar light-flashes paradigms but can also be present for other visual stimuli (e.g., faces) & is largest over the occipital regions.

- Negative peak may be present at same latency over frontal, central areas.

Friday, January 14, 2011 Adult Peak Components

P1 or P50 (visual) - P1 amplitude generally varies with amount of attention in Posner’s attention cueing paradigm & in spatial selective attention experiments.

- P1 reflects suppression of noise because amplitude decreased for unattended locations but did not increase for attended stimuli.

- P1 amplitude also increased when speed of response was emphasized, suggesting that P1 may also reflect level of arousal.

Friday, January 14, 2011 Adult Peak Components

P1 or P50 (visual)

- Sources identified using PET, BESA, and LORETA methods in ventral and lateral occipital regions (Clark, et al., 1996; Gomez, et al., 1994).

- Suggests striate (Strik, et al., 1998) or extrastriate (posterior fusiform gyrus) origin (Heinze, et al., 1994).

- Rossion, et al. (1999) in a face identification paradigm reported similar sources and sources in posterior- parietal regions, suggesting additional involvement of dorsal and ventral neural components.

Friday, January 14, 2011 N1 (N100)

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Friday, January 14, 2011 N1 (N100)

 N1 typically occurs approximately 100 ms after stimulus onset.

 One of easiest components to identify regardless of specific analysis approach.

 Good convergence in findings based on analyses of PCA factor scores (Beauducel, et al., 2000), baseline to peak amplitude (Pekkonen, et al., 1995; Sandman & Patterson, 2000), and baseline to peak latency (Segalowitz & Barnes, 1993).

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Friday, January 14, 2011 N1 (N100)

 N1 assumed to reflect selective attention to basic stimulus characteristics, initial selection for later pattern recognition, & intentional discrimination processing.

 Peak latency & amplitude depend on stimulus modality. Auditory stimuli elicit a larger N1 with shorter latency than visual stimuli (Hugdahl, 1995).

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Friday, January 14, 2011 N1 or N100 (Auditory)

 Maximum amplitude over frontocentral areas (Vaughn & Ritter, 1970) or vertex (Picton, et al., 1974).

 Some studies differentiate into 3 different components with maximum amplitudes over temporal areas (latency 75 ms and 130 ms) & over vertex (latency 100 ms; McCallum & Curry, ‘80; Giard, et al., ‘94).

 Naatanen and Picton (1987) reviewed the 3 components of N1. Proposed that early temporal and vertex components reflect sensory and physical properties of the stimuli (e.g., intensity, location, timing in regards to other stimuli) while later temporal component are less specific and reflect transient arousal.

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Friday, January 14, 2011 N1 or N100 (Auditory)

 NOTE, majority of studies treat N1 as single component occurring 100 ms after stimulus onset with maximum amplitude at the vertex electrode.

 N1 amplitude enhanced by  increased attention to stimuli (Hillyard et al, 1973; Knight, et al., 1981; Ritter, et al., 1988; Mangun, 1995)  increasing inter-stimulus interval (Hari, et al., 1982).

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Friday, January 14, 2011 N1 or N100 (Auditory)

 N1 most likely generated by sources in primary auditory cortex in the temporal lobe (Vaughn & Ritter, 1970).

 MEG, BESA, and lesions studies consistently localize auditory N1 in superior temporal plane (e.g., Papanicolaou, et al., 1990; Scherg, et al., 1989; Knight, et al., 1988).

 However, several studies proposed additional sources in frontal lobe that could be activated from temporal lobe (e.g., Giard, et al., 1994).

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Friday, January 14, 2011 N1 or N100 (VISUAL)

 Usually largest (maximum) over occipital region (Hopf, et al., 2002) or inferior temporal regions (Bokura, et al., 2001).

 Amplitude larger in discrimination tasks, but smaller if short ISIs. [** could disappear]

 N1 discrimination effect attributed to enhanced processing of attended location (Luck, 1995), not due to arousal because amplitudes are larger in tasks placing no emphasis on the speed of response .

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Friday, January 14, 2011 N1 or N100 (VISUAL)

 Not affected by inhibition (no Go/No-Go response differences).

 Like auditory N1, visual N1 occurs at 100 ms over central midline sites & 165 ms over posterior sites.

 Anterior N1 = response preparation because eliminated if no motor response required. 

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Friday, January 14, 2011 N1 or N100 (VISUAL)

 Located visual N1 sources in inferior occipital lobe and occipito-temporal junction using a combination of techniques (MEG, ERP, and MRI), Hopf et al. (2002).

 However, Bokura et al., (2001) using the LORETA approach, identified additional sources of the visual N1 in the inferior temporal lobe.

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Friday, January 14, 2011 QUESTIONS ???

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Friday, January 14, 2011 P2

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Friday, January 14, 2011 P2

 Like N1 and P1, long considered “obligatory cortical potential” since it has low inter-individual variability and high replicability

 Identified in many different cognitive tasks including selective attention, stimulus change, feature detection processes, and short-term memory.

 P2 sensitive to stimulus physical parameters such as loudness.

 Participant differences such as reading ability also change P2 amplitude to auditory stimuli.

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Friday, January 14, 2011 P2 (Auditory)

 P2 often occurs together with N1, yet peaks can be dissociated.

 P2 scalp distribution less localized than N1 & has its highest amplitude over central region.

 Temporal peak of P2 can occur over a broader latency range than the preceding peaks, ranging from 150 - 275 ms.

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Friday, January 14, 2011 P2 (Auditory)

 P2 can be double-peaked.

 Similar to N1, P2 has been consistently identified by analysis procedures:  PCA factor scores  (Beauducel, et al., 2000)  Baseline to peak amplitude  (Beauducel, et al., 2000; Sandman, & Patterson, 2000)  Baseline to peak latency  (Segalowitz & Barnes, 1993)

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Friday, January 14, 2011 P2 (Auditory)

 Generators for auditory P2 thought centered mainly in primary & secondary auditory cortices.

 Both auditory N1 and P2 often represented by 2 dipoles: one in primary auditory cortex and one in secondary auditory cortex.

 Using BESA and LORETA to identify dipole locations for the N1/P2 component, Mulert et al. (2002) identified one in superior temporal region with a tangential orientation while second was located in temporal lobe with a radial orientation. These dipoles reflected primary and secondary cortices, respectively. 147

Friday, January 14, 2011 P2 (VISUAL)

 P2 amplitude increases with complexity of the stimuli.

 Topographic distribution of visually elicited P2 is characterized by a positive shift at the frontal sites around 150-200 ms after stimulus onset and a large negativity, approximately 200 ms following stimulus onset at the occipital sites

 Using BESA dipole analysis, Talsma and Kok (2001) reported a symmetrical dipole pair localized in the inferior occipital (extrastriate) areas. Findings suggest that both topographic distribution and dipole position varied slightly when attending vs. not attending to visual images. 148

Friday, January 14, 2011 QUESTIONS ???

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Friday, January 14, 2011 N2

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Friday, January 14, 2011 N2

 Influenced by features of the experiment, such as modality and stimuli presentation parameters.

 Shares some of its functional interpretation with mismatch negativity (MMN) because both indicate a detection of a deviation between a particular stimulus and the subject’s expectation.

 However, unlike the MMN, the subject MUST pay attention to the stimuli.

 Ken Squires, et al. (1975) first reported this component. Ss viewed 2 stimuli. When the following image did NOT MATCH what was expected, a larger N2 occurred over frontal regions. 151

Friday, January 14, 2011 N2

 N2 has multiple psychological interpretations including:

 orienting response (Loveless, 1983),  stimulus discrimination (Satterfield, et al., 1990),  target selection (Donchin, et al., 1978),  reflecting task demands (Johnson, 1989; Duncan, et al., 1994).

 N2 has more inter-individual variation (Michalewski, et al., 1986; Pekkonen, et al. 1995).

 N2 is smaller in amplitude & shorter in latency for shorter ISIs (Polich & Bondurant, 1997).

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Friday, January 14, 2011 N2 Topography

 N2 topographic distribution depends on sensory stimulus modality:

 Auditory elicit largest N2 amplitude at vertex. Scalp current density analysis indicate bilateral sources in supratemporal auditory cortex.

 Visual elicited highest N2 amplitude over preoccipital region.

 N2 to visual stimuli varied based on the stimuli type, such as written words, pictures of objects, or human faces.

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Friday, January 14, 2011 N2 Sources

 Using intracranial electrodes placed directly on cortex, letter-strings of recognizable nouns produced N2 component at 4th occipital gyrus near occipitotemporal sulci. Pictures of complex objects, (cars, butterflies) resulted in N2 response over inferior lingual gyrus medially & middle occipital gyrus laterally. Effect not present for scrambled pictures.  Face recognition tasks elicit N2 over fusiform gyrus & inferior temporal or occipital gyri just lateral to the occipito-temporal or inferior occipital sulci (see N170).  Such differing distributions indicate N2 may reﬂect category-speciﬁc processing (Allison, et al., 1999).

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Friday, January 14, 2011 N2 and Inhibition

 N2 associated with Go/No-Go paradigm, in which subject responds to some stimuli (Go trials), but inhibits response to another class of stimuli (No-Go trials).

 ERPs on No-Go trials are characterized by a large negative peak relative to the Go trials between 100 and 300 ms after stimulus onset (response inhibition ??).

 N2 occurred both in relation to overt & covert responses, indicating that N2 Go/ No-Go effect not due only to motor responses. Instead, N2 present whenever responses must be interrupted.

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Friday, January 14, 2011 N2 and Inhibition

 Amplitude and polarity of N2 inhibition response changes depending on the complexity of the task.

 In some instances, the Go/No-Go response has been reported as a positive peak, suggesting this pattern was due to large amplitude of the P300 in difficult tasks.

 N2 was larger when subjects have less time to respond.

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Friday, January 14, 2011 N2 and Inhibition

 N2 for the visual & auditory task is especially strong over fronto-central electrodes when the Go response is withheld.  Scalp distribution differs from Error Related Negativity (ERN) that occurs approximately 125 ms after an incorrect response.  N2 response engages different processes than the error monitoring processes reflected in the ERN.

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Friday, January 14, 2011 N2 and Inhibition

 Mathalon et al. (2003) using ERP and fMRI identiﬁed activation of caudal and motor anterior cingulate cortices during both correctly and incorrectly inhibited responses.  These sources differed from ERN responses that were related to caudal and rostral anterior cingulate cortices.  Reinforces view the N2 reﬂects inhibitory responses distinct from error-related negativity. 158

Friday, January 14, 2011 QUESTIONS ???

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Friday, January 14, 2011 Mismatch Negativity (MMN).

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Friday, January 14, 2011 Mismatch Negativity (MMN).

 Naatanen et al. (1978) first described MMN wave as a negative deflection, latency = 100 - 250 ms.

 Amplitude largest frontal & central electrode sites.

 MMN is elicited using an “oddball paradigm” where an occasional deviant stimulus is presented in a stream of more frequent standard stimuli.

 Test-retest reliability.

 Because MMN paradigms require no attention to the stimuli, widely used in developmental research. 161

Friday, January 14, 2011 Calculating the MMN

Traditional: Subtract the averaged waveform of all standard stimuli FROM the averaged waveform of all deviant stimuli collected during the same test session.

Alternative (2004): Present uninterrupted string of standard stimuli midway through experimental session to provide a alternative baseline for calculating the MMN.

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Friday, January 14, 2011 Kraus, McGee, Carrell, Zecker, Nicol, & Koch, 1996

Friday, January 14, 2011 Mismatch Negativity (MMN)

 MMN evoked by any perceivable physical deviance from the standard stimulus (e.g., changes in tone duration, frequency, intensity, and ISI).

 Numerous theories  ”Memory trace" - MMN elicited in response to violations of simple rules governing properties of information - violation of an automatically formed, short-term neural model or memory trace of physical or abstract environmental regularities  Population of sensory afferent neuronal elements that respond to sound, and; ii) a separate population of memory neuronal elements that build a neural model of standard stimulation and respond more vigorously when the incoming stimulation violates that neural model  "Fresh afferent" - sensory afferent neuronal elements that are tuned to properties of the standard stimulation respond less vigorously upon repeated stimulation. Thus when a deviant activates a distinct new population of neuronal elements that is tuned to the different properties of the deviant rather than the standard, these fresh afferents respond more vigorously.  Sensory afferents are memory neurons. 164

Friday, January 14, 2011 Mismatch Negativity (MMN) Auditory

 MMN often used to test ability of subject to discriminate linguistic stimuli (e.g., speech sounds with different voice onset time or place of articulation.

 Data analyzed by subtracting average ERP elicited by standard stimuli from average ERPs for the deviants.

 This subtracted component generally displays an onset latency as short as 50 ms and a peak latency = 100 - 200 ms (Naatanen, 1992).

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Friday, January 14, 2011 Mismatch Negativity (MMN) Sources for auditory stimuli

 MEG: significant differences between dipoles produced by deviants differing in intensity, frequency and duration (Rosburg, 2003).  Dipoles for frequency and duration deviants located significantly inferior in comparison to the source of intensity deviants and differed significantly from each other in the anterior-posterior direction.  All dipoles located within temporal lobes.  Leibenthal et al. (2003) recorded fMRI and ERP data simultaneously to an MMN task.  Main areas of increased BOLD signal in right superior temporal gyrus & right superior temporal plane.

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Friday, January 14, 2011 Mismatch Negativity (MMN) Features influencing MMN

 Negative wave usually associated with MMN.

 Reports of positive wave around 200 ms corresponding to the MMN response (Leppanen, et al., 2002).

 The reason for this difference may be due to differences in filter settings. **

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Friday, January 14, 2011 Mismatch Negativity (MMN) Features influencing MMN

 Some reports indicate substantially reduced MMN response in subjects not attending to the stimuli

 Probability deviant stimuli influences effect.

 Must maintain balance between presenting enough deviant trials to obtain low-noise average responses, and not allowing the subject to habituate to the deviant, thus diminishing effect.  Size of MMN response decreased (non linear),  Time for habituation varies as function of stimulus complexity.

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Friday, January 14, 2011 Mismatch Negativity (MMN) Visual

MMN is found for visual stimuli (Tales, Newton, Troscianko & Butler, 1999).

Source Localization techniques suggest involvement of primary visual cortex and adjacent areas (Gratton, 1997; Gratton, et al. 1998).

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Friday, January 14, 2011 N170 Face Processing

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Friday, January 14, 2011 N170  N170 ranges between 156 & 189 ms. Associated with visual processing of human faces.

 Topographic distribution for both familiar & unfamiliar faces largest over occipito-temporal regions.

 Amplitude significantly larger when viewing faces than other natural or human-made objects.

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Friday, January 14, 2011 N170

 Prosopagnosia Patients do not show an N170 response to faces.

 N170 not specific to human faces but expert object recognition (Tanaka & Curran, 2001)

 Intracranial recordings of EP & fMRI point to fusiform gyrus as neuroanatomical substrate of N170. BUT source localization of N170 using BESA identified source in lateral occipitotemporal region outside fusiform gyrus.

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Friday, January 14, 2011 QUESTIONS ???

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Friday, January 14, 2011 P300 - Two Components

 P300a component associated with the automatic 'Orienting Reflex'

 P300b component associated with controlled processing (most studied)

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Friday, January 14, 2011 P300 Odd-ball tasks

S. Sutton, M. Braren, J. Zublin, and E. John, (1965) Evoked potential correlates of stimulus uncertainty Science, 150, 1187–1188.

Friday, January 14, 2011 P300 Odd-ball tasks  P300 amplitude increases to infrequent stimulus

S. Sutton, M. Braren, J. Zublin, and E. John, (1965) Evoked potential correlates of stimulus uncertainty Science, 150, 1187–1188.

Friday, January 14, 2011 P300 Odd-ball tasks  P300 amplitude increases to infrequent stimulus  Frequent 80% of trials, infrequent 20%

S. Sutton, M. Braren, J. Zublin, and E. John, (1965) Evoked potential correlates of stimulus uncertainty Science, 150, 1187–1188.

Friday, January 14, 2011 P300 Odd-ball tasks  P300 amplitude increases to infrequent stimulus  Frequent 80% of trials, infrequent 20%  Requires attention & response to infrequent stimulus

S. Sutton, M. Braren, J. Zublin, and E. John, (1965) Evoked potential correlates of stimulus uncertainty Science, 150, 1187–1188.

Friday, January 14, 2011 P300 Odd-ball tasks  P300 amplitude increases to infrequent stimulus  Frequent 80% of trials, infrequent 20%  Requires attention & response to infrequent stimulus  Controls important

S. Sutton, M. Braren, J. Zublin, and E. John, (1965) Evoked potential correlates of stimulus uncertainty Science, 150, 1187–1188.

Friday, January 14, 2011 P3a

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Friday, January 14, 2011 P3a

 P3a, frontal maximum scalp distribution. Slightly shorter latency for visual vs. auditory and somatosensory stimuli.

 Frontal P3a occurs when subject not required to actively respond to the targets (N. Squires, et al., 1975) or when novel stimulus is added to the standard 2-stimulus oddball paradigm.

 Frontal P3a assumed to reflect involuntary attention as well as inhibition. In Go/No-Go paradigms, P3a larger in amplitude in No-Go than Go conditions (maximal at parietal sites for Go). 177

Friday, January 14, 2011 P3a

 Neural substrate in medial parietal lobe (early: 317 ms) and in the left superior prefrontal cortex (late: 651 ms) for Go trials;

 Sources for No-Go trials (365 ms) originate in left lateral orbitofrontal cortex.

 P3a reduced by lesions to frontal cortex (Knight, 1991).

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Friday, January 14, 2011 P3b or “P300”

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Friday, January 14, 2011 P3b or P300  Most extensively researched ERP component.  Sutton et al., 1965: pronounced positivity occurring in response to unexpected stimulus approximately 300 ms after stimulus onset.

 Oddball most typical paradigm for eliciting P3b component, - a target stimulus presented infrequently among more common distracter stimuli.

 To get P3, subject must pay attention and respond to stimuli (unlike MMN) and the ratio of target to distracter stimuli must be low (fewer targets -> larger peak).

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Friday, January 14, 2011 P3b or P300

 AMPLITUDE affected by attention, stimulus probability, stimulus relevance, amount of processing resources available (e.g., single vs. dual tasks, quality of selection, and attention allocation.

 Interstimulus interval length affects AMPLITUDE independently of stimulus probability with shorter intervals resulting in larger P3b or P300.

 LATENCY varies with stimulus complexity, effectiveness of selection, and sustained attention.

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Friday, January 14, 2011 P3b or P300

 Visual P3 has larger & longer latency than auditory P3.

 P3 largest over parietal & midline regions.

 Auditory stimuli elicited shorter latency P3 over parietal regions, and longer latency over central sites.

 Functional interpretation of classic P3b diverse –  indicator of memory updating (Donchin & Coles, 1988)  reﬂects a combination of processes that vary by task and situation, including more elaborate active stimulus discrimination and responses preparation.

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Friday, January 14, 2011 P3b or P300

 P3 latency assumed to reﬂect the duration of stimulus evaluation.

 P3 component attracted attention in clinical studies. Because P3 amplitude varies with the amount of attention paid to stimuli, this component widely studied in populations with attention deﬁcits (e.g., ADHD) - interpreted to reﬂect information regarding various attentional functions.

 P3 latency reported related to cognitive abilities with shorter latencies associated with better performance

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Friday, January 14, 2011 P3b or P300

 Sources of P3 not clearly identified but some expected to be in medial temporal lobe, including hippocampal region related to memory (Donchin, 1981; Paller, McCarthy, et al, 1992), parahippocampal gyrus, amygdala, or thalamus (Katayama, et al., 1985).  Lesion data suggest multiple generators, including temporo- parietal junction (Knight et al, 1989). Tarkka et al., (1995) investigated possible sources and reported that combining different locations produced better model.  MEG analyses located sources in floor of Sylvian fissure (superior temporal gyrus) and deeper sources in thalamus- hippocampus.

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Friday, January 14, 2011 QUESTIONS ???

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Friday, January 14, 2011 N400

“He spread the warm butter with socks.”

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Friday, January 14, 2011 N400 Sentence Completion

 N400 larger for unexpected, low probability endings.

Friday, January 14, 2011 N400 Sentence Completion

 N400 larger for unexpected, low probability endings.  Fixed intervals between words

Friday, January 14, 2011 N400 Sentence Completion

 N400 larger for unexpected, low probability endings.  Fixed intervals between words  Words presented one at a time

Friday, January 14, 2011 N400 Sentence Completion

 N400 larger for unexpected, low probability endings.  Fixed intervals between words  Words presented one at a time  Usual interval 1 S.

Friday, January 14, 2011 N400

 Negative component approximately 400 ms after stimulus onset.

 Usually associated with semantic comprehension in both visual and auditory sentence comprehension tasks.

 First identified by Kutas and Hillyard (1979).

 Elicited by anomalies in American Sign Language.

 N400 did not occur when participants presented with anomalies in music (Besson, et al., 1994).

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Friday, January 14, 2011 Kutas & Hillyard, 1980

Friday, January 14, 2011 N400 study with children

 The train runs on a track (CC)  The train runs on a crack (CI)  Child presses either red or green key to indicate if the sentence “sounds ok or funny”.  36 sentences for each condition.  All sentences 6 words in length.  Total data points digitized = 300

Friday, January 14, 2011 N400

12 year olds Word n=68

ms 0 250 500 700

Incorrect Correct

Friday, January 14, 2011 N400 Paradigm

 Words of a sentence were visually presented one after another at fixed intervals in a serial manner.

 Last word of the sentence either congruous (“He took a sip from the water fountain”) or incongruous but syntactically appropriate (“He took a sip from the transmitter”) with rest of the sentence.

 Incongruous words elicited larger amplitude N400 response than congruous words for both auditory and visual stimuli.

 N400 amplitude correlated with degree of incongruency of final word to sentence (e.g., “ transmitter”)

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Friday, January 14, 2011 N400

 Kutas and Hillyard (1983): N400 effect only held true for semantic, but not syntactic deviations.

 Supposedly listeners use information from the wider discourse when interpreting appropriateness of particular word (van Berkum, et al., 2003).

 N400 also elicited in semantic word pairs (Rugg, 1985), semantic priming tasks (Bentin, et al., 1985; Ruz, et al., 2003) and matching semantic material to visual displays (Huddy, et al., 2003).

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Friday, January 14, 2011 N400 (Modalities)

 For both visual and auditory displays, the N400 is larger for anomalous endings than expected endings over the parietal and temporal regions of the right hemisphere.

 But there are modality effects:  N400 is earlier in the visual (475 ms.) than auditory (525 ms) modality but only over the temporal, anterior temporal and frontal sites (Holcomb, et al., 1992).  Earliest peak in the visual modality is over parietal & temporal sites, while in the auditory modality it is over parietal & occipital sites (Holcomb, et al., 1992).

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Friday, January 14, 2011 N400 (Asymmetries)

 Activation in left hemisphere occurrs earlier than activation in the right) in ONLY visual modality (Holcomb, et al., 1992).

 N400 not specific to written words, because spoken words (McCallum, et al., 1984; Holcomb, et al., 1992; Connolly & Phillips, 1994) & pictures (Nigam, et al., 1992) elicit N400.

 N400 response also elicited by incongruent solutions to mathematical multiplication problems (Niedeggen, et al., 1999).

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Friday, January 14, 2011 N400 & Attention

 Still Unclear:  Amount of attention necessary to produce N400,  Cognitive processes involved (Osterhout & Holcomb, 1995).

 Holcomb (1988) reported N400 more robust when attention required but occurs when participants not attending to stimuli.

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Friday, January 14, 2011 N400 & Attention

 However, Bentin et al. (1995) reported (dichotic listening task) that N400 was absent for material presented in unattended ear.

 Amount of effortful semantic processing required is unclear. Kutas and Hillyard (1993) reported N400 effect even in tasks not requiring semantic processing although Chwilla et al. (1995) found no N400 when attention not directed to meaning of stimuli.

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Friday, January 14, 2011 N400 & Sources

 Likely multiple generators that are functionally (Nobre & McCarthy, 1994) and spatially (Halgren, et al., 1994; McCarthy, et al., 1995) segregated.

 Recent work points to parahippocampal anterior fusiform gyrus as generator (McCarthy et al, 1995).

 MEG studies pinpoint lateral temporal region as origin of N400 response (Simos, et al., 1997).

 Intracortical depth recordings using written words point to medial temporal structures near hippocampus & amygdala (Halgren, et al., 1994).

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Friday, January 14, 2011 Late Positive Component (LPC)

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Friday, January 14, 2011 Late Positive Component (LPC)

Positive-going ERP component. Studies of explicit recognition memory. Largest over parietal scalp sites (mastoid reference). Begins approximately 400-500 ms after stimulus onset. Duration = 200 ms ERP "old/new" effect.

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Friday, January 14, 2011 Late Positive Component (LPC)

S given list to learn. ERPs recorded to new list including old and new words. S to indicate old vs. new words. Typical larger LPC to old vs new words.

Also done as continuous test - each trial S indicates if old vs. new item.

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Friday, January 14, 2011 Late Positive Component (LPC)

ERP & fMRI indicate lateral parietal cortex, perhaps with medial temporal lobe and hippocampus.

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Friday, January 14, 2011 QUESTIONS ???

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Friday, January 14, 2011 ERN Error Related Negativity

ERN reﬂects activity of a brain system that detects & corrects for errors.

Friday, January 14, 2011 ERN Paradigm

 Two ways to generate an ERN response:  following an incorrect response  during feedback of incorrect choice

Hajcak, Holroyd, Moser, Simons, 2005; Holroyd, & Coles, 2002; Holroyd, Nieuwenhuis, Yeung, Cohen, 2003

Friday, January 14, 2011 ERN

206

Friday, January 14, 2011 ERN Paradigm

 During speeded  For reinforcement response timing tasks, negativity around 250 ms indicates tasks, an incorrect performance was response produces a incorrect negative peak ~ 100  Miltner, Baun & Coles, 1997  Negativity changes in ms amplitude for incorrect  Gehring, Goss, Coles, Meyer & Donchin, 1993 responses in high reward conditions or correct responses in low reward condition  Holroyd, Nieuwenhuis, Yeung, & Cohen, 2003

Friday, January 14, 2011 ANALYSIS-Feedback

 Amplitude for ERN measured from baseline to peak between 160 ms to 240 ms following feedback  Holroyd, Nieuwenhuis, Yeung & Cohen, 2003  Holroyd et al., (2003) used algorithm to identify amplitude of the greatest negativity in the peak starting at the slope of the first negativity through 325 ms

 Latency measures start at the maximum component amplitude Friday, January 14, 2011 ANALYSIS - Incorrect Response

 Amplitude measured early: 50 - 110 post incorrect response  Luu et al., 200  Usually look at incongruent trials (i.e. Flanker task/go-no go task)  Generate individual waveforms for error trials  **Some groups used smoothing techniques with a nonphase-shifting single pass 17-point moving average (34 ms, approximately 3 db down at 15 Hz) --Santesso, Segalowitz & Schmidt, 2005  Filters set around 20 Hz offline  Holroyd and Colleagues

Friday, January 14, 2011 ERN and Personality

 High Negative affect  10-year old children (high neuroticism) results ranked on Junior in larger amplitude on Eysenck Personality initial tasks Questionnaire show  Tucker et al., 1999 different ERN  ERN reflects certainty of  High psychoticism and loss (greater low lie scores result in realization=greater ERN) smaller ERN   Investment in task Similar to adults: see Dikman and Allen (2000) changes ERN  ERN affected by  Holroyd and Coles, 2002; Scheffers personality and concern and Coles, 2000 of task performance

Santesso, Segalowitz, & Schmidt,(2005)

Friday, January 14, 2011 Source

 Within the anterior cingulate cortex (ACC), mesencephalic dopamine neurons synapse on motor neurons and cause behavior to occur (e.g. pushing correct button)  Basal ganglia mediated by feedback and stimulus input impact ERN generated by the electrical charge of neurons synapsing on the ACC.  When events are worse than expected, decrease in dopamine activity disinhibits dendrites in ACC, resulting in a negative waveform, ERN

Friday, January 14, 2011 Source

The Anterior Cingulate Cortex

212

Friday, January 14, 2011 Feedback-Related Negativity

• A negative deﬂection in the waveform approximately 250-350 ms after the participant given negative feedback (Miltner, Braun, & Coles, 1997) • Thought to originate in the anterior cingulate cortex (Ruchsow, Grothe, Spitzer, Kiefer, 2002).

Friday, January 14, 2011 Feedback-Related Negativity

• Generated without the individual having a choice in responding (Yeung, Holroyd, & Cohen, 2005) • Generated without the individual responding (Donkers, Nieuwenhuis, & van Boxtel, 2005)

Friday, January 14, 2011 Feedback Negativity

0.1-30Hz @ 250Hz

Friday, January 14, 2011 Feedback Negativity

0.1-30Hz @ 250Hz

Friday, January 14, 2011 Scalp Topographies

11.2

-11.5

Win [Average: 19_7622f_rps.ref] Draw [Average: 19_7622f_rps.ref] Lose [Average: 19_7622f_rps.ref] 00:00:00.200 Win Draw Lose

Friday, January 14, 2011 Rock, Paper, Scissors

You Lose

Friday, January 14, 2011 CNV - Contingent Negative Variation

218

Friday, January 14, 2011 CNV - Contingent Negative Variation

 Negative deflection.  Typically elicited in a Go/No-go paradigm between a warning stimulus (S1) and an imperative stimulus (S2).  Can sub-divide into early & late components.

 Early component = "O" or "Orienting" wave.

 Late component = "E" or "Expectancy" wave.

 Thought to reflect anticipation of a response to S2.

219

Friday, January 14, 2011 Habituation

 Decline in amplitude & latency after repeated presentations (~ 3 trials)

Friday, January 14, 2011 Habituation

 Decline in amplitude & latency after repeated presentations (~ 3 trials)  Amplitude rebounds after stimulus change

Friday, January 14, 2011 Habituation

 Decline in amplitude & latency after repeated presentations (~ 3 trials)  Amplitude rebounds after stimulus change  Fixed, short ISI and repeating same stimulus enhance habituation effects

Friday, January 14, 2011 QUESTIONS ???

221

Friday, January 14, 2011 ERP Paradigms

 Strengths and weaknesses

Friday, January 14, 2011 ERP Paradigms

 Strengths and weaknesses  Guides research

Friday, January 14, 2011 ERP Paradigms

 Strengths and weaknesses  Guides research  Often different from main stream behavior-based literature

Friday, January 14, 2011 ERP Paradigms

 Strengths and weaknesses  Guides research  Often different from main stream behavior-based literature  Can create tunnel-vision effects

Friday, January 14, 2011 ERP Paradigms

Research Paradigm Effects

ERP & Language: Recent Research History Over The Last Four Decades

Friday, January 14, 2011 1970 - 1979

Begleiter & Platz (1969). N100---P160 - N400 Buchsbaum & Fedio (1969). P190 - 280 Buchsbaum & Fedio (1970). P190 - 280 Cohn (1971) N30-50 P125 Wood, Goff, & Day (1971).! N100 Shelburne (1972). P165 - 245, P285 Molfese (1972) N100 - P200 Matsumiya et al. (1972). P60-N90-P140- N180 Lenhardt (1973). N100 P200 Dorman (1974).!! ( N75 - P225) Neville (1974) N100 P180 N220 Wood (1975)!!! !N100 Friedman et al. (1975) N100 P300 Galambos et al. (1975) N100 P300 * Shucard et al. (1977). Chapman et al. (1977). * Kostandov & Arzumanov (1977). N200 P300 Chapman et al. (1978). * Molfese (1978a).!!!! N45 P135 ! N450 Molfese (1978b).!!!! N70 P300 Molfese (1979). N100 P300 Molfese (1979). P60 N250 P300 N370 Pace, et al. 1979). Molfese (1979). Hillyard & Woods (1979) N100 N500 Chapman et al. (1979). *

Friday, January 14, 2011 1980 - 1984

Chapman et al. (1980). * Grabow et al. (1980). Kutas, & Hillyard, 1980 (V) N400 Molfese (1980a). (N110 - P190) P330 Molfese (1980b).! P170 N460 Molfese, Erwin, & Deen (1980).! P198 Neville (1980) N100 P180 Papanicolaou (1980). P92 N133 Boddy & Weinberg, (1981) N1 P2 P3 Lawson & Galliard (1981a).! N100 - 200 Lawson & Galliard (1981b).! N100 - 200 Jacobson & Gans (1982).! N100 - 200 Kutas & Hillyard (1982) (V) N400 Neville et al. (1982). Fischler et. al. (1983) (V) N400 Fischler et al (1983). N340 Gelfer (1983).! P160 Kutas & HIllyard (1983) P200-700 N300-400 P400 - 700 Kutas & Hillyard (1983) (V) N300 - 400, N400 700 Molfese & Schmidt (1983).! N70 P170 P290 N460 Papanicolaou et al. (1983). N78 P167 Polich & McCarthy. (1983) P300 Ritter et al. (1983) Rugg (1983a) P670 Rugg (1983b) N100 - P187 P300 P637 Fischler et al (1984). N320 - N480 McCallum et al. (1984) (A) N212 N456 Molfese (1984). N100 P300 N400 ! P500 Friday, January 14, 2011 1985 - 1989 Fischler et al (1985). N320 Fischler et. al. (1985) (V) N400 Molfese (1985). Molfese & Molfese (1985). Molfese, et al. (1985). P315 ! N475 Molfese, Buhrke, & Wang (1985). !N95 ! Molfese, Buhrke, & Wang (1985). ! ! P340 Novick et al. (1985). Pollich (1985). (V) N400 Boddy, (1986) N1 P2 N340 Erwin (1986). N45 N350 N485 Licht et al. (1986). Lovrich et al. (1986) P250 N310 P445 P485 Molfese & Searock (1986). N 100 !P150 !N260 N390 N470 Neville et al., (1986) (V) N150 P220 N410 Bentin, (1987) N400 Herning et al. (1987) P250 N480 Katayama et al (1987). P300 N310 Rugg, (1987) P300 N400 Rugg, (1987) N140 P200 LPC Holcomb (1988) N400 Licht et al. (1988). N530 Lovrich et al. (1988) N310 P350-375 P540 O'Halloran et. al. (1988) (V) N400 Pollich et al (1988) P300 Czigler & Szenthe (1989) 300 600 Segalowitz & Cohen (1989). P35 N135 ! N390 Segalowitz & Cohen (1989). N85 N220 ! N435 Friday, January 14, 2011 1990 - 1992 Barrett et. al. (1990) (V) N400 Holcomb & Neville (1990) N2 N400 *Sams et al. (1990) N100 N220 Stewart & Connolly (1990) (V) N200 N400 Van Petten & Kutas (1990) (V) N400 Ardal et. al. (1991) (V) N400 Erwin et al. (1991). N200 Neville et al. (1991) N125 P2 N300 - N400 P500 - 700 Van Petten et al. (1991) N400 Besson, et al., 1992 (V) N400 Connolly,et al., 1992 (A) N200 N400 Gunter et al. (1992) (V) P260 N340 P550 Koyama et al. (1992) N370 LPC Kraus et al. (1992) N235 Nigam et al. (1992) (V) N400 Osterhout &Holcomb (1992) N350 - 500 P600

Friday, January 14, 2011 1993 - 1994 Bentin et al, (1993) N100 N400 Berman et al. (1993) P350 P600 Curran, et al., 1993 (V) N450 LPC Friederici et al. (1993) N180 N400 P600 Hagoort et al. (1993) N250-600 (P500 700 Karniski,et al., 1993 (A) N250 SW (418 - 530) Kraus et al. (1993) N100 N215-N238 P3a Kutas (1993) (V) N400 Lovrich et al. (1993) P475 Mitchell et. al. (1993) (V) N400 Osterhout & Holcomb (1993) [A] P50 300 RH P300 500RH, PZ N500 800LH Praamstra et al. (1993) N400 [late negativity] Rosler et al (1993) N400 _ 700 Rosler et al. (1993) N400-700 P700 1200 *Sharma et al (1993). N200 - P300 Van Petten (1993) (V) N400 Connolly, et al. (1994) (A) N400 Gunter et. al. (1994) (V) N400 Lovrich et al. (1994) N2 P300 P600 Munte et al. (1994) N100 P580 Nobre et al, (1994) (V) N332 N386 N410 Osterhout et al. (1994) N350 - 450 P500 800LH Perez-Abalo et al. (1994) N400 N450 Pratarelli et al. (1994) N1 - P2 N400 St George et. al. (1994) (V) N400

Friday, January 14, 2011 1995 - 1998

Chwilla et al. (1995) P300 N400 Connolly, et al., (1995) (V) N270 N365 Friederici (1995) (V/A) N400 Friederici (1995) N200 N400 P600 Hamberger et al (1995) P380 N400 P600 Kraus et al. (1995) N100 N200 Kuperman et al. (1995) N400 *Maiste et al (1995) N60-120 N120 - P210 ! P500 - 700 Mecklinger et. al. (1995) (V) N400 Pulvermuller et al. (1995) N160 P200 N340 - 500 N600 - 1000 Schlaghecken et al. (1995) N400 LPC Friederici et al. (1996) N370 N400 500 Hagoort et al. (1996) P2 N400 McKinnon & Osterhout (1996) N1 P2 N400 Nizikiewicz et al., (1996) (V) N200 N400 Kazmerski & Friedman 1997) P3 N400 Lovrich et al. (1997) N480 Swab et al. (1997) N400 Brualla et al. (1998) N400 N570 N680 Gunter et al. (1998) N1 P2 N400 Kiefer et al. (1998) P2 N400 Kutas et al., (1998) (V) N200 N400 McPherson et al. (1998) N350 N450 Moute et al., (1998) (V) N250 N400 Paller et al (1998) 300 750 Pratarelli et al. (1998) P2 N400

Friday, January 14, 2011 QUESTIONS ???

230

Friday, January 14, 2011