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ERP Waveforms. A Darren Parker Presentation. Presentation of ERP Data. Single channel waveforms Topographies (or Topos) ERP data can be used to infer sources (source analysis, beyond this presentation). A Typical Waveform. Waveform Properties. X-Axis: Time
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ERP Waveforms A Darren Parker Presentation
Presentation of ERP Data • Single channel waveforms • Topographies (or Topos) • ERP data can be used to infer sources (source analysis, beyond this presentation)
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.
Scalp Topographies (Topos) Red = Positive Blue = Negative Time Points
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)
ERN • Response related potential. • Results from when an individual produces an error. • Location shown in diagram below, top of scalp at Cz. Error Correct
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.
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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