Technicals of Electroencephalography (EEG) Flashcards
Explain electroencephalography
-> Non-invasive method to understand the cognition of the brain when performing certain tasks.
-> measures the electrical activities in the brain
-> when neurons communicate with each other, a tiny fluctuation of electrical signals is generated.
-> The electrodes measure the signals
-> EEG doesn’t measure an activity of one neuron, but a bunch of them when doing the same thing
Who founded the EEG method?
Hans Berger
Example of an EEG experiment
To have a participant press a button when he sees a stimulus.
-> When he sees the stimulus, there will be an increase in electrical activity in the visual cortex.
-> When he presses a button, there will be an increase in electricity activity in the motor cortex
What are the usage of the ground and reference electrodes?
For providing consistency and accuracy for the EEG.
the reference electrodes are either on the tip of the nose or mastoids
Explain filters
Some of the signals picked up by the EEG have to be filtered as they do not reflect the activity of the neurons.
1. Band-pass filter: Signals that are smaller than 1 Hz and larger than 35 Hz, as these signals cannot reflect activities of the brain.
2. Notch filter: Either at 50 or 60 Hz (depending on the country), which is the line noise
Explain artefacts.
Some of the signals, even though are within the range of useful signals, they can be contaminated, which are called artefacts.
1. Skin Potential: Signals generated when the participant sweats.
2. Eyeblink artefacts: Signals generated when the participant blinks.
3. Muscle artefacts: Signals generated when the participants moves
Explain why do we need electrodes near the eyes.
Because the cornea of the eye has a large positive polarity and the retina has a large negative polarity. Electrodes near the eyes can pick up the signals from an eyeblink, which can be easily removed by mathematical algorithms and Independent Component Analysis (ICA)
What is the type of potential that we detect by EEG?
Post-synaptic potentials
Explain the neurophysiology of EEG Signal
Check notes
What is the inverse problem?
We know how the signals move in the brain. However, these signal movements can be caused by various reasons and activities, which does not give us an absolute understanding of how neurons work
What is the most typical system used in EEG?
The international 10-20 system
What smears signal of the EEG
meninges, skull, and CSF
