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Stephen, that's a tricky problem with no good answer. IMHO the best way of dealing with all these types of 'structured noise' is to remove their effect during pre-processing (motion-correction etc.) If you actually want to remove certain TRs from your measurements then I'd recommend not doing it from the filtered functional data - if the data is so bad that you decide to throw it away it certainly shouldn't be used during filtering, e.g. if there is a large intensity dropout at some TR this will have a negative impact on temporal filtering etc. In such cases you might even be better off by replacing the data by the average of neighbouring TRs prior to pre-processing. cheers christian On 13 Apr 2004, at 17:23, Stephen Wilson wrote: > Thanks for your replies, Jen and Christian. But I want to exclude some > volumes from the middle of the middle of the run. This means they still > need to be there when FEAT calculates the convolution with the > hemodynamic > response, whereas if I manipulate the input prior to running FEAT, then > FEAT will have no way of knowing that volumes were removed, so no way > of > knowing how to predict the response. > > There are several reasons I can think of why one might want to do this: > (1) to exclude volumes in which face/mouth motor tasks are performed > (this > is my present goal); (2) to exclude volumes with scanner artifacts; > (3) to > exclude volumes where there are saccades, or swallowing, or such, if > you > can monitor these. > > It would be nice if there was an option to input a file of time points > to > be excluded... > > best, > > Stephen > -- Christian F. Beckmann Oxford University Centre for Functional Magnetic Resonance Imaging of the Brain, John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK Email: [log in to unmask] - http://www.fmrib.ox.ac.uk/~beckmann/ Phone: +44(0)1865 222782 Fax: +44(0)1865 222717