What are the characteristics of normal beta activity on EEG?

Updated: Oct 09, 2019
  • Author: Selim R Benbadis, MD; Chief Editor: Helmi L Lutsep, MD  more...
  • Print
Answer

Answer

Normal beta activity has the following characteristics:

  • Frequency (by definition) greater than 13 Hz - Common 18-25 Hz, less common 14-16 Hz, and rare 35-40 Hz [2]

  • Location - Mostly frontocentral but somewhat variable; some describe various types according to location and reactivity: generalized, precentral, and posterior

  • Morphology - Usually rhythmic, waxing and waning, and symmetric

  • Amplitude - Usually range of 5-20 mV

  • Reactivity - Most common 18- to 25-Hz beta activity enhanced during stages I and II sleep and tends to decrease during deeper sleep stages; central beta activity may be reactive (attenuates) to voluntary movements and proprioceptive stimuli; in infants older than 6 months, onset of sleep marked by increased beta activity in central and postcentral regions [3]

    A sample of awake EEG showing the normal or usual A sample of awake EEG showing the normal or usual amount of beta activity. As shown here, beta activity is often easier to identify during relaxed wakefulness or early drowsiness.
    This is the normal amount of beta activity, fronta This is the normal amount of beta activity, frontally predominant, with waxing and waning amplitude.

Did this answer your question?
Additional feedback? (Optional)
Thank you for your feedback!