ERPs and Attention Flashcards
who conducted the first human EEG recording
Hans Berger 1942
what is the most important difference between EEG?ERPs and TMS?
Manipulation vs measurement
–> in TMS you can manipulate different areas of the brain, in EEG you just have raw data and can measure activity when person does things
odd numbers on EEG electrodes represent what hemisphere?
odd = left hemi even = right
what cells are measured with ERPs?
cortical pyramidal cell (basic input out cell of cerebral cortex)
–> measures post activation potential (flow from dendrite to dendrite)
what is the net charge outside a cell
negative
the current flows through the cell completing the circuit.
-> polarity reverses with? (2)
- inhibitory transmitter
- PSP on cell body and basal dendrites
polarity at the scalp depends on?
orientation of the cortical surface ad position of reference electrode
what is the collective electrical field generated by multiple activated neurons called?
equivalent current dipole
scalp- recorded potentials are possibly only for _______ structures with consistent _______, primarily ______ cortex
- layered, orientations
- cerebral
voltages spread through the brain by _______ ________ nearly at the speed of light. Voltage everywhere except at _________ - _________ transition
–> skull causes lateral spread (like spraying hose on cardboard)
- volume conduction
- positive - negative
delta waves are at what frequency and related to what?
- 1-3 Hz
- slow wave sleep
theta waves are at what frequency and related to what?
- 4-7 Hz
- non-REM sleep, misc cognitive
alpha waves are at what frequency and related to what?
- 8-12 Hz
- awake, relaxed, (zoning)
Beta waves are at what frequency and related to what?
- 12-25 Hz
- mentally active
gamma waves are at what frequency and related to what?
- 25 + Hz
- Local synchrony
7 ERP components
- visual sensory
- auditory sensory,
- P3 family
- N2 family
- Mismatch negativity (MMN)
- Langauge Related (N400)
- Response related : lateralized readiness potential (LRP), error- related negativity (ERN)
extrastriette cortex, sensitive to visual features, arousal, attention
P1 (the first big positivity)
extrastriate cortex, parietal, and fontal sub components, sensitive to attention, N170 is a sub component
N1 (the first big negativity)
Brainstem auditory evoked responses (BAERs; aka auditory brain stem responses or ABRs)
- -> modulated by ?
- -> brain region?
- brief clicks used as stimuli
- cochlea, auditory nerve, brainstem nuclei
Midlatency responses (MLRs)
- brain regions?
- modulated by?
- medial geniculate nucleus and primary auditory cortex
- highly focused attention
auditory “long latency” sensory responses
- subcomponents?
- sensitive to?
- at least 3 NI subcomponents
- attention
P3 amplitude depends on?
P3 effects cannot occur until after?
P3 latency is tied to?
- probability of the task defined stimulus category
- categorization
- to the amount of time required to perceive and categorize a stimulus (stimulus evaluation time)
tells us about at what point in time we see differences in processing a right visual field target versus a left
N2pc
elicited by an auditory stimulus that physically mismatches preceding stimuli
mismatch negativity (MMN)
what wave is associated with meaning of a word not fitting in with the context.
N400
risks and discomforts of EEG
- none
- net or cap on head, gel /saline in hair, remain still.
what are ERPs good for? (3)
- Determine whether an experimental manipulation
influenced Process A or Process B
- What was the onset time of the difference?
- Which ERP component was affected by the manipulation? - Identifying multiple neurocognitive processes
- A given behavioral effect is often accompanied by multiple
ERP effects (different components)
- Easy to identify multiple processes contributing to behavior - Covert monitoring of processing
- Processing can be measured without a behavioral response
(or from subjects who cannot easily respond)
- Did the brain do something that was not evident in behavior?
ERPs may be bad when… (5)
- You desire certainty about the neuroanatomical locus of
an effect - You are interested in activity that is slow (>~2 s) or not
time-locked to a sudden, observable event - You cannot collect large numbers of trials in each critical
condition
- Long period of time between trials
- Severe adaptation of response over trials
- Need to surprise subjects - The process of interest does not have an ERP signature
- Subjects make frequent head, eye, or mouth
movements during the time period of interest
- Speech is particularly bad (tongue has strong dipole)
attention is applied by _____ modulation
top - down (executive function)
what ERP component is affected by the attentional blink?
P3
