What is the function of a low-frequency filter (LFF) in EEG recordings?

The role of a low-frequency filter (LFF) in EEG recordings is to eliminate low-frequency drift, which can interfere with the clarity of the brainwave signals being monitored. EEG signals are comprised of varying frequency components, and low-frequency drifts, often caused by factors such as slow movement of the electrode or changes in baseline, can obscure the meaningful data from higher frequency brain activity. By applying a low-frequency filter, the EEG technician can effectively minimize these unwanted low-frequency signals, which allows for a more accurate representation of higher frequency activity that is crucial for the interpretation of the EEG.

In contrast, reducing noise from high-frequency activity pertains more to the role of a high-frequency filter, and amplifying low-frequency signals would counteract the intended purpose of an LFF. Additionally, preserving fast events and spikes is essential when interpreting transient brain activities, but the function of a low-frequency filter is specifically focused on addressing low-frequency components rather than enhancing them. Therefore, understanding the primary function of the LFF helps clarify its importance in obtaining clearer and more diagnostically useful EEG readings.