Transcript second presentation

Event-related potentials (ERPs)
Jarrod Blinch
motorbehaviour.wordpress.com
May 31st, 2011
Type of electrodes
• Non-polarised silver-chloride (Ag/AgCl)
• Tin
• Gold or platinum
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How many trials?
• EEG 50 uV
• ERPs
– 60 trials for large component (~10 uV, P300,
RP/LRP)
– 150 medium (~5 uV)
– 400 small (~1-2 uV)
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Overview
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Event-related potentials (ERPs)
Advantages and disadvantages
ERP components and waveform peaks
Strategies to interpret ERP components
Quantifying noise
Components
– Readiness potential (RP, LRP)
– P300 (P3a, P3b)
• Fractionating information processing
– Osman and Moore, 1993 (LRP)
– Luck, 1998 (P3b)
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Event-related potentials (ERPs)
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Averaging to generate ERPs
Tiny effects
Relying on previous ERPology
Reliability
– Low within-participant variability
– High between-participant variability
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Advantages and disadvantages
Advantages
• Continuous measure of
processing
• Independent of a
behavioural response
• Evoked or emitted
potentials
• Noninvasive
• Temporal resolution
Disadvantages
• Functional significance
• Tiny effects
• Spontaneous or induced
potentials
• Spatial resolution
• Peaks versus components…
• Latency jitter…
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Imperative
stimulus
Stimulus
identification
Response
initiation
Response
selection
Response
programming
Reaction time
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ERP components and waveform peaks
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Strategies to interpret ERP components
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Focus on a specific component
Use well-studied experimental manipulations
Focus on large components
Isolate components with difference waves
Focus on components that are easily isolated
Use component-independent experimental
designs
7. Hijack useful components from other domains
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Quantifying Noise
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Overview
•
•
•
•
•
•
Event-related potentials (ERPs)
Advantages and disadvantages
ERP components and waveform peaks
Strategies to interpret ERP components
Quantifying noise
Components
– P300 (P3a, P3b)
– Readiness potential (RP, LRP)
• Fractionating information processing
– Osman and Moore, 1993 (LRP)
– Luck, 1998 (P3b)
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P300
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Readiness potential (RP)
MP
Late RP
Early RP
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Lateralised readiness potential (LRP)
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Imperative
stimulus
LRP
P300
Stimulus
identification
Response
selection
Response
initiation
Response
programming
Reaction time
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Psychological refractory period
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Bottleneck
Stimulus onset
asynchrony (SOA)
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Osman & Moore, 1993
LRP
Stimulus
identification
Response
selection
Response
programming
Stimulus
identification
Bottleneck
Response
selection
Response
programming
Stimulus
identification
Response
selection
Bottleneck
Response
programming
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*
L *
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Luck, 1998
P300
Stimulus
identification
Response
selection
Stimulus identification and Bottleneck
Stimulus
identification
Response
programming
Response
selection
Response selection and Bottleneck
Response
programming
Response
programming
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Event-related potentials (ERPs)
Jarrod Blinch
motorbehaviour.wordpress.com
May 31st, 2011