RPSGT RPSGT Electroencephalography & Signal Interpretation 1 — Questions and Answers
Question 1: According to AASM scoring rules, which EEG electrode derivations are used for adult sleep staging?
- F4-M1 only
- C4-M2 only
- O2-M1 only
- F4-M1, C4-M2, and O2-M1 (Correct answer)
Correct answer: F4-M1, C4-M2, and O2-M1
AASM recommends three EEG derivations (F4-M1, C4-M2, O2-M1) with contralateral backup electrodes to capture activity from frontal, central, and occipital cortical regions.
Question 2: K-complexes are most prominently identified in which EEG derivation?
- Occipital (O1/O2)
- Central (C3/C4)
- Frontal (F3/F4) (Correct answer)
- Temporal (T3/T4)
Correct answer: Frontal (F3/F4)
K-complexes are generated in the frontal cortex and are best visualized in frontal EEG derivations (F3/F4), though they are visible across channels.
Question 3: Alpha rhythm is defined as EEG activity in the frequency range of:
- 0.5–2 Hz
- 4–8 Hz
- 8–13 Hz (Correct answer)
- 13–30 Hz
Correct answer: 8–13 Hz
Alpha activity is defined as EEG oscillations between 8–13 Hz, predominantly seen in occipital derivations during relaxed wakefulness with eyes closed.
Question 4: Sleep spindles are generated primarily by which brain structure?
- Hippocampus
- Amygdala
- Thalamus (Correct answer)
- Basal ganglia
Correct answer: Thalamus
Sleep spindles are generated by thalamocortical circuits, with the thalamic reticular nucleus acting as the pacemaker for the 12–15 Hz oscillations.
Question 5: Which EEG waveform, when occupying ≥20% of a 30-second epoch, defines N3 (slow-wave) sleep?
- Theta waves (4–7 Hz)
- Delta waves (0.5–2 Hz, >75 µV amplitude) (Correct answer)
- Sleep spindles (12–15 Hz)
- Alpha waves (8–13 Hz)
Correct answer: Delta waves (0.5–2 Hz, >75 µV amplitude)
N3 sleep is scored when high-amplitude delta waves (>75 µV, 0.5–2 Hz) occupy ≥20% of the 30-second epoch, reflecting deep slow-wave sleep.
Question 6: Saw-tooth waves on EEG during PSG are characteristic of which sleep stage?
- N1
- N2
- N3
- REM (Correct answer)
Correct answer: REM
Saw-tooth waves are 2–6 Hz sharply contoured, notched waveforms occurring in bursts during REM sleep, often preceding bursts of rapid eye movements.
RPSGT RPSGT Electroencephalography & Signal Interpretation 1
According to AASM scoring rules, which EEG electrode derivations are used for adult sleep staging?