EEG Normal EEG Waveforms 2

Question 1

What is the normal frequency range of the posterior dominant rhythm (alpha rhythm) in a healthy awake adult?

Accepted Answer

8-13 Hz

Answer

The normal adult posterior dominant rhythm falls within the alpha frequency band of 8-13 Hz, typically with a mean frequency around 10 Hz. It is best seen over the occipital regions with eyes closed.

Question 2

Sleep spindles are a hallmark of which stage of sleep?

Accepted Answer

Stage N2 sleep

Answer

Sleep spindles (11-16 Hz bursts lasting 0.5-2 seconds) are the defining feature of Stage N2 sleep. They are generated by thalamic reticular nucleus oscillations and are best seen over central regions.

Question 3

Vertex sharp waves (V waves) during drowsiness are maximally recorded at which electrode position?

Accepted Answer

Cz

Answer

Vertex sharp waves are high-amplitude, surface-negative sharp transients maximal at the vertex (Cz electrode) that appear during drowsiness and Stage N1 sleep as a normal finding.

Question 4

The lambda wave is a positive sharp transient that occurs in the occipital region during:

Accepted Answer

Active visual scanning of a complex image or environment

Answer

Lambda waves are positive sharp transients over the occipital regions that occur during visual scanning with saccadic eye movements. They represent cortical responses to visual input during active looking.

Question 5

K-complexes are characterized by which of the following features?

Accepted Answer

A biphasic wave with initial sharp negative component followed by a positive slow wave, maximal at the vertex during N2 sleep

Answer

K-complexes are large biphasic waves with an initial sharp negative deflection followed by a slower positive component, maximal at Fz/Cz, occurring spontaneously or in response to stimuli during Stage N2 sleep.

EEG - Electroencephalography Practice Test

EEG - Electroencephalography Practice Test

EEG Normal EEG Waveforms 2