Back to PLS HelpPosted on 08/23/16 16:03:08
Number of posts: 6
Hi,
We are trying to setup a blocked fMRI analysis. Is it necessary to speciy a seperate baseline condition for the rest periods? The manual shows that a baseline condition is specified for the rests in between task blocks, is this always needed, or is PLS able to detect the rests between each condition onset on its own?
Also, we are doing a longitudinal study and are interested in effects of time and group. For each subject, is it better to have two runs (time1, time2) with two conditions each (control, interference)? Or one run with four conditions (control1, control2, interference1, interference2)?
Thank you in advance!
Antoni
Replies:
Posted on 08/24/16 06:39:39
Number of posts: 394
Hi Antoni - you do not explicitly need a baseline task as PLS calculates the % signal change from a reference time point. I am not clear on the design, however, so can you please elaborate on your design and the question you are testing so I can be sure?
Posted on 08/24/16 07:21:55
Number of posts: 6
Hi Randy, Thanks again for the quick reply!
We are using a multi-source interference task with two conditions (control and interference) to look to at group differences (between intervention and control groups) across two timepoints (before and after intervention). The task is the same at both timepoints, but reaction time is expected to change as a result of the intervention. The control and interference conditions alternate, with rest blocks in between each, where nothing appears on the screen in the scanner. Let me know if you need more information..
Antoni
Posted on 08/24/16 14:04:44
Number of posts: 394
Hi Randy, Thanks again for the quick reply!
We are using a multi-source interference task with two conditions (control and interference) to look to at group differences (between intervention and control groups) across two timepoints (before and after intervention). The task is the same at both timepoints, but reaction time is expected to change as a result of the intervention. The control and interference conditions alternate, with rest blocks in between each, where nothing appears on the screen in the scanner. Let me know if you need more information..
Antoni
thanks - so unless the rest condition is of interest, I would not use it and just focus on the control and interference conditions. The rest condition may be useful to look at general activation/deactivation, but not much else.
Login to reply to this topic.
