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Dear FSL experts, We are running resting-state functional connectivity analyses and have a question regarding bandpass temporal filtering. We like to bandpass filter our data with fslmaths –bptf option but would like to be sure we understand the procedure correctly. Apparently, the sigma range for the bandpass should be specified in sigma VOLUMES instead of SECONDS. With a TR=2.5 and bandpass range of 0.009-0.10 Hz we figured out the following and would love to know whether this is correct. Sigma in Seconds = (1/hz)/TR Highpass Sigma in sec 44.444 = (1/0.009) / 2.5 Lowpass Sigma in sec 4.0 = (1/0.10) / 2.5 Sigma in Volumes = Sigma in seconds / TR Highpass Sigma in volumes 17.778 = 44.444 / 2.5 Lowpass Sigma in volumes 1.60 = 4.0 / 2.5 So our bandpass range in sigma volumes should be 17.778 - 1.60, and this would be fed into fslmaths: fslmaths functional.nii.gz -bptf 17.778 1.60 BP_filter.nii.gz Is this correct? Thanks for the input! Regards, Mauro