If I have understood you correctly, you have 2 TRs at the start of each on or off period that you want to exclude from the regressors of interest. If you want to do this, you should do it with extra "dummy" EVs which just pick out the corresponding TRs you want to "skip".

If you are doing this to deal with haemodynamic delays, then you are instead better off using the haemodynamic response function (HRF) modelling (with temporal derivatives), which is the default in feat.

Dr Mark Woolrich.

Oxford University Centre for Functional MRI of the Brain (FMRIB),

John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK.

Tel: (+44)1865-222782 Homepage: http://www.fmrib.ox.ac.uk/~woolrich

On 29 Jul 2006, at 18:48, Gonzalo Rojas Costa wrote:

Hi:

I have an fMRI study with TR = 4 seconds, 10 temporal dynamics per off-
on period (40 seconds duration each off-on period)... I must skip the
first two dynamics of each off-on period to process the study... How can I
do it with FSL ?...

Sincerely,

Gonzalo Rojas Costa
Service of Neuroradiology
Institute of Neurosurgery Dr. Asenjo