Difference between revisions of "Alpha rhythm"
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− | Posterior dominant | + | *Frequency: 8-13 Hz |
+ | *Posterior dominant | ||
+ | *Amplitude: 10-80 microV | ||
+ | *Wax and wane in amplitude | ||
+ | *Most prominent with eyes closed and relaxed | ||
+ | *Suppressed with eyes open, mental stress or sleep | ||
+ | *Left-right difference <1 Hz in frequency and <50% in amplitude (amplitude is usually higher on the right side) | ||
+ | *Alpha variants are normal sub- and supraharmonic frequencies of the alpha rhythm, particularly in children and young adults ([[Slow alpha variant]] and [[Fast alpha variant]]) | ||
+ | *2-5% of healthy people does not have a detectable alpha rhythm | ||
− | |||
− | + | *The posterior basic rhythm frequency is age dependent: | |
+ | {| class="wikitable" | ||
+ | |- | ||
+ | ! scope="col"| Age | ||
+ | ! scope="col"| Frequency | ||
+ | |- | ||
+ | |0-3 months | ||
+ | |No posterior basic rhythm | ||
+ | |- | ||
+ | |4 months | ||
+ | |3-4 Hz | ||
+ | |- | ||
+ | |5 months | ||
+ | |5 Hz | ||
+ | |- | ||
+ | |1 year | ||
+ | |6-7 Hz | ||
+ | |- | ||
+ | |3 years | ||
+ | |8 Hz | ||
+ | |- | ||
+ | |7 years | ||
+ | |9 Hz | ||
+ | |- | ||
+ | |> 60 years | ||
+ | |Decrease by 0.08 Hz/year | ||
+ | |} | ||
− | [[ | + | |
+ | |||
+ | ---- | ||
+ | '''''Alpha rhythm of 9 Hz, posterior dominant with waxing and waning (source)''''' | ||
+ | |||
+ | [[File:Alpha rhythm average e.png|border|1500px|left]] | ||
+ | |||
+ | ---- |
Latest revision as of 15:45, 30 March 2017
- Frequency: 8-13 Hz
- Posterior dominant
- Amplitude: 10-80 microV
- Wax and wane in amplitude
- Most prominent with eyes closed and relaxed
- Suppressed with eyes open, mental stress or sleep
- Left-right difference <1 Hz in frequency and <50% in amplitude (amplitude is usually higher on the right side)
- Alpha variants are normal sub- and supraharmonic frequencies of the alpha rhythm, particularly in children and young adults (Slow alpha variant and Fast alpha variant)
- 2-5% of healthy people does not have a detectable alpha rhythm
- The posterior basic rhythm frequency is age dependent:
Age | Frequency |
---|---|
0-3 months | No posterior basic rhythm |
4 months | 3-4 Hz |
5 months | 5 Hz |
1 year | 6-7 Hz |
3 years | 8 Hz |
7 years | 9 Hz |
> 60 years | Decrease by 0.08 Hz/year |
Alpha rhythm of 9 Hz, posterior dominant with waxing and waning (source)