Part I: EventRelated Brain Potentials and Behavior I

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Part I Event-Related Brain Potentials and
Behavior I
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(ERP) Event-Related Potentials

• A variety of brain responses that show stable
  time relationships to actual or anticipated
  stimuli
• Endogenous produced by internal events occur
  independently of external stimuli.
• Exogenous produced as a reaction to specific
  external events.

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4 types of ERPs

• Sensory
• Motor
• Long-Latency
• Steady Potential Shifts (SPS)

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How do I find the ERP?

• Derived from EEG
• Usually smaller than the background EEG activity
• Evoked potential extracted from the EEG via
  averaging technique
• Computer sums it up

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• Reaction time (RT) a function of many factors,
  including stimulus intensity. Quick reactions are
  related to shorter ERP latencies.
• Bisensory stimulation the simultaneous, or near
  simultaneous stimulation of two sensory systems

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Movement Related Potentials

• Brain responds both before and after
• Impulses from 2 senses an interact to influence
  ERPs recorded at the cortex

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Asymmetries with

• Visual Stimulation
• Auditory Stimulation (sounds and words)
• Evaluative Categorizations

• Cognitive functions (intelligence, verbal and
  spatial tasks)
• Drama drama!!

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Wake up kids! The ERP and Sleep

• Classification of sleep stages discussed on
  Monday enable us to study ERPs as a function of
  these stages

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Overall findings regarding ERPs during sleep
indicate

• That they exist

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Part IIEvent-Related Slow Brain Potentials and
Behavior
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Slow Potentials

• Also known as slow waves
• Take longer to develop than sensory-evoked
  potentials or motor potentials
• Endogenous in nature
• Produced by internal processes vs. outside stimuli

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Types of Slow Potentials

• Contingent Negative Variation (CNV)- effected by
  the expectancies of stimuli
• Readiness Potential (RP)- involved in the
  intention to move
• P300 (P3)- involved in decisions

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Contingent Negative Variation (CNV)

• Steady negative shift in brain activity
• Occurs when there is an initial stimulus (S1)
  followed by a second stimulus (S2) that requires
  a response from the participant

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Two Shapes of CNV

• Type A- fast rise time
• Generally occur when participants are unsure when
  S2 will be presented
• Type B- slow rise time
• Occurs when participants are more certain of when
  S2 will be presented

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Waves Seen in CNV

• Orientation Wave (O wave)
• Evident about 650 msec after S1
• Expectancy Wave (E wave)
• Occurs at the end of the interstimulus interval
  (ISI)

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Type A vs. Type B
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Sexual Preference Study

• Performed by Costell, Lunde, Kopell, Wittner
  (1972)
• Both genders showed larger CNVs when presented
  with stimuli of the opposite sex
• Large CNVs were also present for the
  anticipation of opposite sex stimuli
• CNV was found to be a useful index of sexual
  preference in college students
• It has been suggested to use CNVs when
  prosecuting sex offenders to determine sexual
  object preference

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Readiness Potential (RP)

• Also referred to as a Bereitschaftspotential
• Slow rising negative wave
• Begins 500-1,000 msec before voluntary movement
  and peaks at time of movement
• Also precedes spontaneous movements

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Piano study

• Participants had at least 20 years of experience
• Compared RPs between playing a single note and
  playing a melody
• RPs were higher in amplitude and started earlier
  when playing the melody
• Also found that frontal areas were stimulated
  before the motor areas showing that the
  movements may begin in the frontal cortex before
  they are initiated in the motor cortex

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P300 Potential (P3)

• ERP wave that occurs about 300 msec after
  stimulation
• Associated with cognitive activities
• Decision making, attention, and discrimination
  are a few examples
• Task-relevant wave more confidence in the task
  appears to yield a higher wave amplitude

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Uses of P300

• Hereditary Component
• People with certain psychiatric disorders are
  found to have smaller amplitudes and longer
  latency P300s
• Schizophrenia and Alcoholism
• Suggests a possible genetic marker that could be
  used to predict psychiatric disorder in a person
• Research on memory- P300 has a much larger
  amplitude with previously learned material vs.
  new material

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Part III Event-Related Brain Potentials and
Behavior II
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Human mental processes related to event related
potentials (ERPs)

• Intelligence
• Stimulus meaning and emotional content
• Linguistic processes
• Classical and operant conditioning
• Sensation and ERPs
• Attention and ERPs
• Perception and ERPs

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Intelligence

• The Neural Efficiency Hypothesis
• Latencies of ERP may be an index of information
  processing efficiency
• The String Hypothesis
• IQ is positively related to complexity of ERP
  trace
• P300 and Intelligence
• Examined P300 response as a link to intelligence
• Possible unbiased measure of intelligence?

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Stimulus meaning and emotional content

• Meaningfulness of stimuli alters the ERP
• Stimulus content, affective value, and
  expectancies
• Emotional effects when presented with different
  stimuli
• Two hemispheres appear to cooperate when
  processing emotional facial expressions

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Linguistic processes

• Sounds produce larger P300 amplitudes than words
• P300 system is engaged whenever task-related
  language stimuli are used
• N400 and semantic mismatch

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Conditioning and ERPs

• Classical conditioning
• Comparison between pairing stimuli and subsequent
  ERPs
• Operant conditioning

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Sensation and ERPs

• Smell
• ERPs elicited by stimulation of olfactory
  receptors
• Taste
• ERPs only visible with salt and sour tastes
• Touch and Pain

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Attention and ERPs

• Selectivity in attention
• Mismatch negativity
• ERP amplitude higher in response to deviant
  stimuli presented in an attended ear than to the
  unattended ear

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Attention and ERPs (cont.)

• Intermodal vs. intramodal selective attention
• Different brain mechanisms may be involved in
  selecting auditory stimuli from other auditory
  stimuli (intramodal) as opposed to selecting
  auditory stimuli from visual stimuli (intermodal)
• Resource allocation

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Perception and ERPs

• Relationships between ERPs and perceptions
  including
• Shape
• Pattern size
• Blurring and pattern perception
• Upper and lower visual fields
• Perceptual discrimination and P300
• Corners
• Orientation of figures
• Visual masking
• Color

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Reference

• Andreassi, J.L. (2000). Psychophysiology Human
  Behavior Physiological Response. Mahwah, NJ
  Lawrence Erlbaum Associates.