Electroencephalography: how the EEG is generated and key patterns
How summed postsynaptic potentials of cortical pyramidal cells and thalamocortical circuits produce the EEG, the normal rhythms and sleep stages, the yield and limits of routine EEG after a first seizure, and the patterns examined in encephalopathy, encephalitis, CJD, absence epilepsy and non-convulsive status.
Tier 2Medical sciences concept
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- The EEG records summed postsynaptic potentials of cortical pyramidal neurons, not action potentials.
- Rhythms come from thalamocortical loops shaped by the ascending arousal systems. They slow with drowsiness, sleep, sedative drugs and diffuse brain dysfunction.
- A routine EEG catches interictal discharges in only 30 to 50% of adults with epilepsy, and about 0.5% of healthy adults show them.
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Sources
- Principles of Neural Science (6th ed.)McGraw Hill (Kandel, Koester, Mack and Siegelbaum, 2021), 2021
- Kane N et al. A revised glossary of terms most commonly used by clinical electroencephalographers and updated proposal for the report format of the EEG findings. Revision 2017. Clin Neurophysiol Pract 2017;2:170-85International Federation of Clinical Neurophysiology, 2017
- Hirsch LJ et al. American Clinical Neurophysiology Society's Standardized Critical Care EEG Terminology: 2021 Version. J Clin Neurophysiol 2021;38:1-29Journal of Clinical Neurophysiology, 2021
- Fisher RS et al. ILAE official report: a practical clinical definition of epilepsy. Epilepsia 2014;55:475-82International League Against Epilepsy, 2014
- Last updated
- 14 November 2026
What changed
- 14 November 2026 Personal emails, About story and Australian-style copy