AFNI Message Board

Dear AFNI users-

We are very pleased to announce that the new AFNI Message Board framework is up! Please join us at:

https://discuss.afni.nimh.nih.gov

Existing user accounts have been migrated, so returning users can login by requesting a password reset. New users can create accounts, as well, through a standard account creation process. Please note that these setup emails might initially go to spam folders (esp. for NIH users!), so please check those locations in the beginning.

The current Message Board discussion threads have been migrated to the new framework. The current Message Board will remain visible, but read-only, for a little while.

Sincerely, AFNI HQ

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Gang Chen
October 26, 2007 01:33PM
> Is there a reason why these long ISI's are, in fact, related optimally to
> power? The only thing I can think of is that sticking a couple of long ones
> in a run decreases expectancy effects and thus expectancy-related noise.
> Is RSFgen designed with such cognitive processes in mind?

No, you've overestimated the IQ of RSFgen. The occurrences of long ISI's are there simply because their presence makes the regressors less correlated with each other, thus leading to higher efficiency/power.

> If BOLD is roughly constant after 20 seconds post stimulus, can I just
> shorten the long ISI's to that amount?

An option could be added in RSFgen to set up an upper bound in ISI in the future. In reality RSFgen is more important in avoiding the worst designs than most efficient ones. So you may just check those designs in the top list and see if you can find one with all ISI's less than 20 sec.

Gang
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Subject Author Posted

RSFgen -- Long ISIs

Thalia Wheatley October 25, 2007 01:56PM

Re: RSFgen -- Long ISIs

rick reynolds October 26, 2007 01:16PM

Re: RSFgen -- Long ISIs

Gang Chen October 26, 2007 01:33PM

Re: RSFgen -- Long ISIs

Thalia Wheatley October 27, 2007 09:51AM