How would a 15Hz high frequency filter affect 15Hz sleep spindles?

In the context of EEG and filtering, a high-frequency filter is designed to remove or attenuate frequencies above a specified threshold—in this case, 15 Hz. Sleep spindles are typically oscillatory brain wave patterns occurring in the frequency range of approximately 12 to 16 Hz.

When a 15 Hz high-frequency filter is applied, it primarily targets the frequencies that are at or above 15 Hz. Sleep spindles, which are centered around this frequency, may partially fall within the range of attenuation. As a result, the amplitude of these sleep spindles would likely decrease because some of the energy associated with the spindle could be filtered out.

The degree of attenuation, often expressed in terms of percentage, indicates how significantly the amplitude is reduced. A 30% decrease in amplitude aligns with the expectations of filtering effects on brain waves that straddle the cutoff frequency. Therefore, the answer indicates that while some of the spindle activity may be preserved, the high-frequency filter would still considerably affect its overall amplitude, leading to a conclusion that the amplitude is decreased by 30%.