Hi,
I have a number of data sets that I have used SPM 2 to analyse, however,
following analysis we have discovered that an air-conditioning unit in the
scanner computer room was switching on an off with a period of 100 seconds.
This switching has introduced a periodic variation of the same frequency in
our data. Our study involves a long scan of 25 minutes (on rats) where we
present a challange for 5 minutes, 5 minutes into the scan. The remainder of
the scan allows the signal to return to baseline. Therefore, the variation
is of a higher frequency than the signal of interest.
Is it possible using SPM 2 to remove this 'high frequency' noise (or could
we band filter it at 100Hz? Would this have any implications for the analysis?
Thanks for your help.
Dave
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