Difference between revisions of "Alpha rhythm"
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*Suppressed with eyes open, mental stress or sleep | *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) | *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 | + | *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 | ||
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| − | '''''Alpha rhythm of 9 Hz, posterior dominant with waxing and waning''''' | + | '''''Alpha rhythm of 9 Hz, posterior dominant with waxing and waning (source)''''' |
| − | [[File:Alpha rhythm average e.png|border| | + | [[File:Alpha rhythm average e.png|border|1500px|left]] |
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Latest revision as of 16:45, 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)
