Topic 8.11 Flashcards
(47 cards)
System of electrode placement for eeg
10/20 % system
What is the nasion?
frontal suture
What is the inion?
occipital protuberance
What does an increased number of electrodes help with?
spatial resolution
4 types of montages EEG
- Sequential
- Referential
- Average reference montage
- Laplacian
alpha wave frequency and amplitude
- 8-13Hz
- 20-200 microV
Beta wave frequency and amplitude
- 14-30 Hz
- < 25 microV
Theta wave frequency
4-7 Hz
Delta wave frequency
0.5 - 4 Hz
Where can alpha waves be mostly found?
occipital lobe
Where can beta waves mostly be found?
temporal and frontal lobe
Gamma wave frequency
30-100 Hz
What are gamma waves for? (2)
- Intense mental activity
- Recollect something from short term memory
When can theta waves show up outside of sleep? (2)
- For children they are present even in awake state
- Disappointment and frustration in adults
When are delta waves present? (2)
- Normal deep sleep rhythm in adults
- Infancy
What is the signal in the EEG?
oscillations of extracellular (field) potentials : alternating EPSP and IPSP
What causes a positive EEG wave?
- Apical IPSP
- Perisomatic EPSP
Mechanism of synchronization of the waves?
thalamocortical synchronization
2 properties of thalamocortical neuron for oscillation?
- recurrent lateral inhibition
- post inhibitory rebound
What is an evoked potential?
Following presentation of a stimulus
What is ERP?
event related potentials : time locked to some “event” (can be different stimuli)
3 examples of evoked potentials
- Auditory evoked potential
- Visual EP
- Somatosensory EP
What is required to detect evoked potentials?
Averaging of multiple EEG
EEG following stimulus = ?
= evoked signal + random noise
