Difference between revisions of "Alpha rhythm"

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*Frequency: 8-13 Hz
 
*Frequency: 8-13 Hz
*Posterior maximum
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*Posterior dominant
 
*Amplitude: 10-80 microV
 
*Amplitude: 10-80 microV
 
*Wax and wane in amplitude
 
*Wax and wane in amplitude
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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.
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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]])
*The posterior basic rhythm frequency is age dependant:
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*2-5% of healthy people does not have a detectable alpha rhythm
**0-3 months: No posterior basic rhythm
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**4 months: 3-4 Hz
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**5 months: 5 Hz
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**1 years: 6-7 Hz
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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
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[[File:Alpha rhythm average e.png]]
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 +
*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
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|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)

Alpha rhythm average e.png