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 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)

Time PointsRed = Positive

Blue = Negative

Advantages/Disadvantages

Waveforms Topographies

Advantages High temporal information.

Pretty.

Shows scalp voltage distribution.

Disadvantages Specific to a single electrode (or area).

Each topo only shows one point in time.

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.ErrorCorrect

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.

Questions?

Thank you for your attention.

Tips always welcome!

Electrode Map