Which region of the brain shows the majority of alpha rhythms during the PSG?

Which region of the brain shows the majority of alpha rhythms during the PSG?

• A. Parietal
• B. Frontal
• C. Occipital
• D. Temporal

Answer: (C)

Alpha rhythm represents the brain’s idle state during relaxed wakefulness, and it’s generated most strongly by the visual cortex located in the occipital region at the back of the brain. When the eyes are closed, the posterior EEG leads over the occipital cortex show a prominent 8–12 Hz rhythm—the occipital alpha. This alpha power is greatest in the occipital area and typically decreases with eye opening or mental activity. In polysomnography, the strongest and most consistent alpha activity is thus seen in the occipital region, making it the region where the majority of alpha rhythms originate. The other regions can exhibit some alpha, but they do not dominate the rhythm like the occipital area.

Alpha rhythm represents the brain’s idle state during relaxed wakefulness, and it’s generated most strongly by the visual cortex located in the occipital region at the back of the brain. When the eyes are closed, the posterior EEG leads over the occipital cortex show a prominent 8–12 Hz rhythm—the occipital alpha. This alpha power is greatest in the occipital area and typically decreases with eye opening or mental activity. In polysomnography, the strongest and most consistent alpha activity is thus seen in the occipital region, making it the region where the majority of alpha rhythms originate. The other regions can exhibit some alpha, but they do not dominate the rhythm like the occipital area.