It looks like one of the NN responses is being totally censored out (which is not so odd). That is one difficulty with IM, there is a reasonable chance that censoring will cover all of the time points for at least one event response, giving you one or more all-zero regressors. To have it proceed, it is necessary to include at least the warned about -GOFORIT level (in this case, 3). But some subjects might have higher levels if this happens more.
The other question is what to do for these events, as you have no estimate of a BOLD response for them. If it is a very low fraction of events, you might choose to ignore them. I am curious what Gang tends to suggest.
- rick
