Dear Spm membersŁ¬
I read several previous SPM emails which have discussed this problem when using long TRs like 7s and 15s, it was suggested that better not to convolution with HRF but simply delay one scan. However, i am using a novel CASL sequence which obtained interleaved EPI images with and without labeling (TR=3s), and i want to run a multiple regression glm analysis only on the EPI images without labeling (normal EPI images) by using the behavioral performances as the user specified regressors (one value for each normal EPI images). Thus, my acquisition protocal for EPI images was TR=3s, but interscan interval = 6s. Should i convolve the regressors with HRF or simply delay the regressors one scan? And, how to convolve a user specified regressor with HRF in SPM99 or SPM2? ˇˇˇˇ
thanks a lot for your comments,
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Hengyi Rao, Ph.D.
[log in to unmask]
Department of Neurology
University of Pennsylvania
3 W Gates
3400 Spruce Street
Philadelphia, PA, 19104
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