2006-12-09 03:04:31 · 4 answers · asked by tokenwhtgrl 2 in Science & Mathematics ➔ Biology
Historically four major types of continuous rhythmic sinusoidal EEG activity are recognized (alpha, beta, delta and theta). There is no precise agreement on the frequency ranges for each type.
Delta is the frequency range up to 4 Hz and is often associated with the very young and certain encephalopathies and underlying lesions. It is seen in stage 3 and 4 sleep.
Delta waves.Theta is the frequency range from 4 Hz to 8 Hz and is associated with drowsiness, childhood, adolescence and young adulthood. This EEG frequency can sometimes be produced by hyperventilation. Theta waves can be seen during hypnagogic states such as trances, hypnosis, deep day dreams, lucid dreaming and light sleep and the preconscious state just upon waking, and just before falling asleep.
Theta waves.Alpha (Berger's wave) is the frequency range from 8 Hz to 12 Hz. It is characteristic of a relaxed, alert state of consciousness. Alpha rhythms are best detected with the eyes closed. Alpha attenuates with drowsiness and open eyes, and is best seen over the occipital (visual) cortex. An alpha-like normal variant called mu is sometimes seen over the motor cortex (central scalp) and attenuates with movement, or rather with the intention to move.
Alpha waves.sensorimotor rhythm (SMR) is a middle frequency (about 12–16 Hz) associated with physical stillness and body presence.
SMR waves.Beta is the frequency range above 12 Hz. Low amplitude beta with multiple and varying frequencies is often associated with active, busy or anxious thinking and active concentration. Rhythmic beta with a dominant set of frequencies is associated with various pathologies and drug effects, especially benzodiazepines.
Beta waves.Gamma is the frequency range approximately 26–100 Hz. Gamma rhythms appear to be involved in higher mental activity, including perception, problem solving, fear, and consciousness.
2006-12-09 03:46:07 · answer #1 · answered by THE UNKNOWN 5 · 0⤊ 0⤋
Probably gamma. Gamma nearly always comes after alpha and beta. They're the first three letters in the Greek alphabet.
2006-12-09 03:06:58 · answer #2 · answered by Amy F 5 · 0⤊ 0⤋
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2016-01-27 23:32:00 · answer #3 · answered by ? 3 · 0⤊ 0⤋
gamma
2006-12-09 05:11:59 · answer #4 · answered by bell 4 · 0⤊ 0⤋