What is the typical frequency range for normal adult alpha activity?

The frequency range for normal adult alpha activity is typically found between 8 to 13 Hz. This range is significant as alpha waves represent a state of relaxed alertness, often observed when a person is awake but in a calm, resting state, such as during eyes-closed relaxation or meditation.

Alpha activity is most prominent over the occipital regions of the brain and tends to diminish or disappear with eye opening, mental exertion, or active concentration. The awareness of this specific range is critical for professionals working in EEG as it helps in the assessment of normal brain function and can indicate deviations in certain neurological conditions.

The other frequency ranges mentioned correspond to different types of brain activity. The 4-7 Hz range is associated with theta waves, which can occur during light sleep or deep relaxation; 14-30 Hz is where beta waves reside, reflecting active thinking and alertness; and 1-3 Hz encompasses delta waves, which are characteristic of deep sleep. Understanding these distinctions is vital for accurate interpretation of EEG findings.