evoked potentials (ep) (a.k.a. event related potentials, erp)
DESCRIPTION
Evoked potentials (EP) (a.k.a. Event related potentials, ERP). Raw signal is “noisy” so we reduce noise by repeating stimulus and averaging potentials A time domain analysis. Time-locked presentations, repeated with EEG. EPs to test sensory pathway integrity. - PowerPoint PPT PresentationTRANSCRIPT
Evoked potentials (EP)(a.k.a. Event related potentials, ERP)
• Raw signal is “noisy” so we reduce noise by repeating stimulus and averaging potentials
• A time domain analysis
Time-locked presentations, repeated with EEG
EPs to test sensory pathway integrity
Letter = Positive or negative deflection
Number = milliseconds (or 100s ms) • Examples
– P300 can occur between 300-800 ms
– N400 may occur prior to it.
task deviant stimuli
Presentations and Responses
• Oddball
Oddball paradigm
• We habituate to regular stimulation– Any sound, image, pattern
• Oddball is the rare event
A A A A C A A [odd=C]
C C C A C C C [odd=A]
• Positive deflections
– P300
• Negative deflections– N100– N400
Atypical housing of language functions in autism
ERP reveals age, diagnoses
Kayser et al, in press
ERD – Event related desynchronization(frequencies may tell us more about mental
operations)
CSA – compressed spectral array
Time domain (ERP)vs Frequency domain (ERD)
task deviant stimuli
• Fewer trials needed than ERP
Assess extent of info processing
Diagnosing with ERD
Effect of sleep deprivation
Different neurophysiological operations reflected in different rhythms (thalamocortical, intracortical)
Topography reveals specific de/activation patterns
Leveraging functional laterality
ERD & PRS
Lie detection
Neuroimaging of Lie detection