1. Basics of EEG recording
BCS204 Week 5.1
2/11/2019

2. Origin of the EEG signal
Pyramidal neurons
Afferent fibers
Hari & Puce (2018)

3. Everything useful in the data?

4. What else goes into the data?
Most common –
Eye blink
Electrooculography (EOG)
Electromyography (EMG)
Electrocardiography (EKG)
Sweating
Line noise (some systems are particularly sensitive to this.)
Response related motion artifacts

5. Practice: quickly identify the one with highest frequency

6. Fourier transform
Luck (2014)

7. The source of EEG signal from an electrode can be from somewhere else!!
Luck (2014)

8. EEG topography
adopted from Harri & Puce (2018)

9. EEG montage: system

10. EEG montage: actiCHamp
Nasion
Preauricular
Preauricular
Inion

11. EEG channels The more the better?  Depending on your purpose
Typically in the increment of 16 or 32 (16, 32, 64, 96, 128, 160, 256)
Reference channel (dedicated or non-dedicated): choose a site with relatively lower activities (common ref sites: earlobe, mastoids, nasion)
One potential advantage of using a high-density system: use averaged reference as reference

12. Typical EEG preparation steps
Obtain subject’s consent
Measure subject’s head circumference to determine the cap size
Find the intersection of preauricular-preauricular and nasion-inion (Cz) (system dependent)
Plug electrodes into the cap (system dependent)
Apply the cap onto subject’s head and plug the electrode cable into the amplifier
Apply gel into the gap between electrode and scalp to lower impedance
Start experiment

13. Typical EEG system setup
EEG recording
Stimuli presentation

14. Type of EEG systems Gel vs. Saline solution Active vs. Inactive
Shielded vs. Unshielded
NRTtoday.com