Beta activity (13-30 Hz) can occur as normal activity or can be abnormal, depending on the location, persistence, and amplitude. Beta activity is sinusoidal in morphology and may appear diffusely or more prominently in the frontocentral regions of normal adults with a low amplitude usually <25μV. Beta is particularly seen in N1 and REM sleep. Beta activity is usually symmetrical in amplitude and frequency but could be asynchronous between the two hemispheres. There is considerable interindividual variability.
Beta activity is more common in infants and young children less than 1½ years old and then diminishes in both amplitude and incidence with increasing age. Whenever beta activity is abundant, other EEG activities, for instance alpha or theta waves, may appear “spiky”. Anxiety can enhance this normal beta activity.
Question:
Beta activity is enhanced by which of the following?
Results
#1. Beta activity is enhanced by which of the following?
Beta activity is enhanced by sedative, hypnotic, or anxiolytic drugs (barbiturates, benzodiazepines), tricyclic antidepressants, chloral hydrate, and alcohol. Beta enhancement by medication is not dose-dependent but depends more on the individual’s sensitivity. Beta activity is usually enhanced in the region of a burr hole or skull defect, commonly referred to as a “breach rhythm”. This is because beta activity is normally more attenuated by intervening tissues (dura, CSF, skull, scalp) between the cortex and scalp.
Resources:
The Normal Asleep EEG (learningeeg.com)
Yamada, Thoru, and Elizabeth Meng. Practical Guide for Clinical Neurophysiologic Testing: EEG. Available from: Wolters Kluwer, (2nd Edition). Wolters Kluwer Health, 2017.
Greenfield, John, L. et al. Reading EEGs: A Practical Approach. Available from: Wolters Kluwer, (2nd Edition). Wolters Kluwer Health, 2020.
