[Eeglablist] Fwd: About filter setting

[Fang-Yu Chang]

Dear eeglablists

I would like to analyze the bereitschaftpotential (BP), and I have 2
questions which are related to set the filter's condition.

First, I set high-pass filter at 1 Hz and low-pass filter at 30 Hz. After
running ica, there  was 30 Hz amplitude in every independent component
(IC). However, high-pass filter at 1 Hz and low-pass at 70 Hz were set, and
there was no amplitude in every IC. I would like to ask how did it happen?

Second, I noticed that there is a difference between setting high-pass
filter at 0.1 Hz and setting high-pass filter at 1 Hz. If high-pass was set
at 0.1 Hz, the amplitude of the peak was about 27 microVolts, but if
high-pass filter was set at 1 Hz, the amplitude of the peak was about 5
microVolts. My vice mentor speculates that BP is a kind of slow wave, so
it's reasonable that we set high-pass filter at 0.1Hz. Nevertheless, we
would like to ask experts' opinions. According to previous studies, the
amplitude of BP is about 10 microVolts in the healthy adults.

The pictures for low-pass filters were set at 70 Hz and 30 Hz separately.
Low-pass filter at 70 Hz
http://imgur.com/L5tAxx6

Low-pass filter at 30 Hz
 http://imgur.com/5SwNDZv

In addition, here is my system information: Matlab is 2014a and eeglab is
13.5.4b.
Thank you.

Sincerely,

Stella Ling
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