Difference between revisions of "Alpha rhythm"

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Frequency: 8-13 Hz
 
  
Posterior dominant
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*Frequency: 8-13 Hz
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*Posterior dominant
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*Amplitude: 10-80 microV
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*Wax and wane in amplitude
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*Most prominent with eyes closed and relaxed
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*Suppressed with eyes open, mental stress or sleep
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*Left-right difference <1 Hz in frequency and <50% in amplitude (amplitude is usually higher on the right side)
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*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]])
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*2-5% of healthy people does not have a detectable alpha rhythm
  
Amplitude: 10-80 microV
 
  
Suppressed with eyes open or mental tension
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*The posterior basic rhythm frequency is age dependent:
  
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{| class="wikitable"
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|-
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! scope="col"| Age
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! scope="col"| Frequency
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|-
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|0-3 months
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|No posterior basic rhythm
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|-
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|4 months
 +
|3-4 Hz
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|-
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|5 months
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|5 Hz
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|-
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|1 year
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|6-7 Hz
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|-
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|3 years
 +
|8 Hz
 +
|-
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|7 years
 +
|9 Hz
 +
|-
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|> 60 years
 +
|Decrease by 0.08 Hz/year
 +
|}
  
[[image:Logo.png]]
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 +
 
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----
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'''''Alpha rhythm of 9 Hz, posterior dominant with waxing and waning (source)'''''
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[[File:Alpha rhythm average e.png|border|1500px|left]]
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 +
----

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)

Alpha rhythm average e.png