In a record with 10 Hz alpha activity, if the display epoch changes from 10 seconds to 20 seconds, the frequency of the activity will be what?

The frequency of an EEG rhythm is defined by the number of cycles or oscillations that occur in a second. Alpha activity, specifically, typically oscillates at around 8 to 13 Hz, with 10 Hz being a commonly recognized frequency within this range.

When the display epoch changes from 10 seconds to 20 seconds, it effectively alters the time window being analyzed but does not impact the inherent frequency of the brain activity recorded. The alpha rhythm remains at 10 Hz, regardless of the display epoch's duration. Therefore, the frequency remains the same regardless of whether you are looking at a 10-second or 20-second segment of the recording.

This concept emphasizes that frequency is a characteristic of the brain waves themselves and is not altered simply by changing the time window for analysis.