The voltage measured by an EEG system is typically expressed in what units?

The voltage measured by an EEG system is typically expressed in microvolts (µV). This choice is correct primarily because the electrical signals produced by neuronal activity in the brain are very small, often in the range of microvolts. The use of microvolts allows for better resolution and sensitivity when measuring these subtle signals, which is crucial for accurately capturing and interpreting brain activity.

In the context of EEG, the measured voltages are commonly in the range of 0 to 100 µV during normal activities, with specific waveforms, such as alpha or beta waves, being characterized by their amplitude in microvolts. This precision in measurement aligns with the physiological scales of brain electrical activity.

Millivolts and volts, while units of voltage, are too large for the small amplitudes typically recorded in EEG. If the expressions were in these units, they would not accurately reflect the low levels of brain electrical activity, potentially leading to misinterpretation of the data. Decibels, on the other hand, are a logarithmic unit often used for sound intensity or other power ratios but are not applicable for direct voltage measurements in EEG systems.