I just look at several flat line EEG brain waves and all of them are not exactly at zero microvolt, in the sense there seems to be always a small signal or irregularities to be seen, as well as baseline offsets. Is it possible for flat line EEG brain wave to be 100% zero microvolt?

These are some examples to be found of non-flat EEGs in the literature, e.g., here and here and here.


Every electronic device generates internal noise (e.g., Stronks et al., 2019), including EEG machines. Further, environmental factors, most notably electrical devices and circuitry, may also impose noise on the EEG signal, think clinical equipment in hospitals, mobile phones etc. So even 'flat EEG's', i.e., isoelectric EEGs obtained in 'brain dead' organisms, aren't perfectly flat. Such EEGs are devoid of physiological (cortical) electrical activity, yet environmental and internal electronic noise still show up in the EEG recording.

- Stronks et al., Ear Hear (2019); 40(6): 1457–66

  • $\begingroup$ You wouldn't even need a brain dead organism or even a brain: just put your electrodes in some conductive agar, saline solution, whatever: you'll never get a flat record for all the reasons pointed out here. $\endgroup$
    – Bryan Krause
    Aug 11 at 15:28

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