ERP Waveforms

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ERP Waveforms

• A Darren Parker Presentation

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Presentation of ERP Data

• Single channel waveforms
• Topographies (or Topos)
• ERP data can be used to infer sources (source
  analysis, beyond this presentation)

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A Typical Waveform
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Waveform Properties

• 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.

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All Channels
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Scalp Topographies (Topos)
Red Positive Blue Negative
Time Points
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Advantages/Disadvantages
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Component Examples

• Response related potentials
• Error Related Negativity (ERN)
• Lateralized Readiness Potential (LRP)
• Contingent Negative Variation (CNV)
• Early Attention related potentials
• P1, N1, P2, N2 and variations on these.
• Later Cognitive related potentials
• P3, N400 (language)

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ERN

• Response related potential.
• Results from when an individual produces an
  error.
• Location shown in diagram below, top of scalp at
  Cz.

Error
Correct
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N170

• 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.

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N400

• 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.
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Questions?
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Thank you for your attention.

• Tips always welcome!

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Electrode Map