[Eeglablist] Sampling rate

[Stephen Politzer-Ahles]

Hi Mori,

In addition to what Makoto pointed out, your new sampling rate needs to be
at or above the Nyquist rate to avoid aliasing---a good rule of thumb is
the sampling rate should be at least 3 times higher than the
highest-frequency signal in the data. So if you low-pass at 40 Hz, for
example, the sampling rate should not be below 120 Hz. Personally, I like
to use 1000 Hz because that just makes the data easy to work with (1 sample
is 1 ms), although that could result in very large files for long
experiments.

Best,
Steve



Stephen Politzer-Ahles
New York University, Abu Dhabi
Neuroscience of Language Lab
http://www.nyu.edu/projects/politzer-ahles/


On Mon, Jun 30, 2014 at 7:04 PM, mori larin <morilarin88 at gmail.com> wrote:

> Dear list,
>
> I am using EEG data and I have two questions:
> 1) I am not sure about sampling rate. The EEG data was recorded at 5000 Hz
> and I have to down sample it for further work. I used 256 Hz and I do not
> know is it correct or not. How should we select the re-sampling rate? Could
> it be any number and which criteria needs to be considered?
>
> 2) For the EEG data which is recorded simultaneously with fMRI data, in
> order to remove gradient and BCG artefacts automatically from the data
> using ICA , should I have to remove gradient artefacts before running ICA
> and then trying to find the remaining effect of gradient artefact in ICA
> components? (and what are the methods to remove it) or I have to run ICA on
> the contaminated data directly? The latter I think I have to expect more
> components associated to gradient artefacts because the amplitude of the
> gradient artefacts are larger than brain signals.
>
> I really appreciate it if you could help me,
>
> Regards,
> Morin
>
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