Hi AFNI experts!

I'm running an amplitude modulation analysis with a trial-by-trial behavioral response as my AM. Therefore, my timing files look like this: onset*behavior:duration. However, for some trials, the participant didn't give a behavioral response. So I'm unsure what to do with those trials. Do I delete them from the timing file (but then I'm not sure if I'm modeling the implicit baseline correctly). Or, is there a way to just have a missing value there so I can still model those trials, but without the AM. Here is an example of a timing file with missing values (I have them currently coded as 99 just so I can visualize them).

63.288*3:3 111.054*3:3 135.688*99:3 146.254*1:3 156.321*4:3 195.021*2:3 260.921*4:3 273.988*5:3
28.576*4:3 40.143*2:3 99.476*4:3 135.676*5:3 156.309*99:3 249.342*5:3 260.909*4:3 286.042*5:3
16*5:3 28.567*5:3 75.834*2:3 122.1*3:3 228.7*2:3 249.333*3:3 260.9*4:3 273.967*4:3

Thank you!