Transcript ERP Waveforms - McMaster University

ERP Waveforms
A Darren Parker Presentation
Presentation of ERP Data
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Single channel waveforms
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Topographies (or Topos)
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ERP data can be used to infer sources
(source analysis, beyond this presentation)
A Typical Waveform
Waveform Properties
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X-Axis: Time
Y-Axis: Voltage in microvolts
(uV)
Channel Labels (Ours vs.
standard 10-20)
Legend describing
conditions
Component labels
Oriented positive up
(sometimes negative up)
Zero point usually stimulus
on-set, but may be
response-locked.
All Channels
Scalp Topographies (Topos)
Red = Positive
Blue = Negative
Time Points
Advantages/Disadvantages
Waveforms
Advantages
High temporal
information.
Topographies
Pretty.
Shows scalp
voltage
distribution.
Disadvantages Specific to a single Each topo only
electrode (or area). shows one point in
time.
Component Examples
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Response related potentials:
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Early Attention related potentials:
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Error Related Negativity (ERN)
Lateralized Readiness Potential (LRP)
Contingent Negative Variation (CNV)
P1, N1, P2, N2 and variations on these.
Later Cognitive related potentials:
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P3, N400 (language)
ERN
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Response related potential.
Results from when an individual produces an
error.
Location shown in diagram below, top of
scalp at Cz.
Error
Correct
N170
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Early stimulus related
potential.
Response to facial stimuli
that gets attenuated to
repeated facial stimuli.
Location in diagram
shown O9, at rear of
head (occipital cortex) on
the left side.
N400
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Late stimulus related
potential.
Negative-up.
Sensitive to semantic
incongruities in language.
Location not indicated in
diagram, but from paper,
Pz. Parietal cortex, central.
Kutas &Van Petten. (1988) “Event-related brain
potential studies of language,” Advances in
Psychophysiology. 3: 139-87.
Questions?
Thank you for your attention.
Tips always welcome!
Electrode Map