Which type of waves have a frequency of 13-35 Hz, an amplitude of less than 30uV, and are present during normal wakefulness when the patient is alert?

Which type of waves have a frequency of 13-35 Hz, an amplitude of less than 30uV, and are present during normal wakefulness when the patient is alert?

• A. Beta waves
• B. Theta waves
• C. Delta waves
• D. Vertex waves

Answer: (A)

Beta activity represents fast, desynchronized brain waves seen when a person is awake and mentally active. They fall in the higher frequency range around 13–30 Hz (often described up to about 35 Hz) and have relatively low amplitude, typically under 30 µV. This pattern matches being alert and engaged in tasks. In contrast, theta waves (slower, 4–7 Hz) appear with drowsiness or light sleep, delta waves (<4 Hz) dominate deep sleep, and vertex waves are transient features mainly seen at sleep onset rather than during sustained alert wakefulness.

Beta activity represents fast, desynchronized brain waves seen when a person is awake and mentally active. They fall in the higher frequency range around 13–30 Hz (often described up to about 35 Hz) and have relatively low amplitude, typically under 30 µV. This pattern matches being alert and engaged in tasks. In contrast, theta waves (slower, 4–7 Hz) appear with drowsiness or light sleep, delta waves (<4 Hz) dominate deep sleep, and vertex waves are transient features mainly seen at sleep onset rather than during sustained alert wakefulness.