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An `!electrogram`! (`!EGM`!) is a recording of `F33f`_`[electrical activity`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Action_potential]`_`f of `F33f`_`[organs`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Organ_(biology)]`_`f such as the `F33f`_`[brain`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Brain]`_`f and `F33f`_`[heart`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Heart]`_`f, measured by monitoring changes in `F33f`_`[electric potential`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Voltage]`_`f.`:cite-ref-1[`F5bf`_`[1`#cite-note-1]`_`f] Historically, it also referred to an instrument to measure atmospheric electrical potential.

>>Contents

• `F0af`_`[Brain`#brain]`_`f

• `F0af`_`[Electroencephalography (EEG)`#electroencephalography-eeg]`_`f

• `F0af`_`[Electrocorticography (ECoG or iEEG)`#electrocorticography-ecog-or-ieeg]`_`f

• `F0af`_`[Eye`#eye]`_`f

• `F0af`_`[Electrooculography (EOG)`#electrooculography-eog]`_`f

• `F0af`_`[Electroretinography (ERG)`#electroretinography-erg]`_`f

• `F0af`_`[Heart`#heart]`_`f

• `F0af`_`[Electrocardiogram (ECG)`#electrocardiogram-ecg]`_`f

• `F0af`_`[Cardiac electrogram`#cardiac-electrogram]`_`f

• `F0af`_`[Other muscles`#other-muscles]`_`f

• `F0af`_`[See also`#see-also]`_`f

• `F0af`_`[References`#references]`_`f

• `F0af`_`[Further reading`#further-reading]`_`f

-─

>>Brain

>>>Electroencephalography (EEG)

An electroencephalogram (EEG) is an electrical recording of the activity of the brain taken from the `F33f`_`[scalp`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Scalp]`_`f. An EEG can be used to diagnose `F33f`_`[seizures`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Seizure]`_`f, `F33f`_`[sleep disorders`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Sleep_disorder]`_`f, and for monitoring of level of anesthesia during surgery.

>>>Electrocorticography (ECoG or iEEG)

An electrocorticogram is an electrical recording of the brain measured intracranially, that is, from within the brain.`:cite-ref-2[`F5bf`_`[2`#cite-note-2]`_`f]

>>Eye

>>>Electrooculography (EOG)

An electrooculogram (EOG) is an electrical recording of the potential between the `F33f`_`[cornea`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Cornea]`_`f and the `F33f`_`[retina`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Retina]`_`f, and does not change with `F33f`_`[visual stimuli`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Stimulus_(physiology)]`_`f. An EOG can measure movements of the eyes and can help in diagnosis of `F33f`_`[nystagmus`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Nystagmus]`_`f.

>>>Electroretinography (ERG)

An electroretinogram (ERG) is an electrical recording of the electrical activity of the retina.

>>Heart

>>>Electrocardiogram (ECG)

An electrocardiogram (ECG or EKG) is an electrical recording of the activity of the heart. The typical meaning of an "ECG" is the 12-lead ECG that uses 10 wires or `F33f`_`[electrodes`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Electrode]`_`f to record the signal across the chest. Interpretation of an ECG is the basis of a number of cardiac diseases including `F33f`_`[myocardial infarction`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Myocardial_infarction]`_`f (heart attack) and arrhythmias such as `F33f`_`[atrial fibrillation`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Atrial_fibrillation]`_`f.

>>>Cardiac electrogram

When electrical recordings are made from the `F33f`_`[skin`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Skin]`_`f, it is considered to be an ECG as described above. However, electrical recordings made from within the heart such as with an `F33f`_`[artificial cardiac pacemaker`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Artificial_cardiac_pacemaker]`_`f or during an `F33f`_`[electrophysiology study`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Electrophysiology_study]`_`f, the signals recorded are considered an "electrogram" instead of an ECG. These signals are not interpreted in the same manner as an ECG.

>>Other muscles

An electromyogram (EMG) is an electrical recording of the activity of a `F33f`_`[muscle`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Muscular_system]`_`f or muscle group. An EMG study can be combined with a `F33f`_`[nerve conduction study`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Nerve_conduction_study]`_`f to diagnose neuromuscular diseases such as `F33f`_`[peripheral neuropathy`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Peripheral_neuropathy]`_`f and `F33f`_`[amyotrophic lateral sclerosis`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Amyotrophic_lateral_sclerosis]`_`f.

>>See also

• `F33f`_`[Radiology`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Radiology]`_`f

>>References

`:cite-note-1`!1.`! `F0af`_`[↑`#cite-ref-1]`_`f "Definition of 'Electrogram'". `*`F33f`_`[Collins English Dictionary`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Collins_English_Dictionary]`_`f`*.

`:cite-note-2`!2.`! `F0af`_`[↑`#cite-ref-2]`_`f `:citerefdubeyray2019`aDubey, A.; Ray, S. (2019-05-29). "Cortical Electrocorticogram (ECoG) Is a Local Signal". `*Journal of Neuroscience`*. `!39`! (22): 4299–4311. `F33f`_`[doi`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Doi_(identifier)]`_`f:10.1523/JNEUROSCI.2917-18.2019. `F33f`_`[ISSN`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=ISSN_(identifier)]`_`f 0270-6474. `F33f`_`[PMC`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=PMC_(identifier)]`_`f 6538865. `F33f`_`[PMID`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=PMID_(identifier)]`_`f 30914446.

>>Further reading

• `:citerefreillylee2010`aReilly, Richard B.; Lee, T. Clive (19 November 2010). "Electrograms (ECG, EEG, EMG, EOG)". `*Technology and Health Care`*. `!18`! (6): 443–458. `F33f`_`[doi`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Doi_(identifier)]`_`f:10.3233/THC-2010-0604. `F33f`_`[ISSN`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=ISSN_(identifier)]`_`f 1878-7401. `F33f`_`[PMID`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=PMID_(identifier)]`_`f 21099006.

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