Hi doug,

Thanks doug.

In our experiment, there are 324s, and TR=2s, two kinds of stimulus. Each one consisted of 3 components(cue 500ms + fixation 500ms + picture 500ms), and will be presented with a interval of 1.5s. After stimulus onset, followed by reaction time. One stimulus will repeat 41 times, the other 40 times.

Based on optseq2 --ntp 162 --tr 2 --psdwin 0 20 --ev ev1 2 40 --ev ev2 2 40 --nkeep 2 --o ex2 --nsearch 1000, how should I modify to get a efficient sequence, as I have no idea about NULL design.

Thanks again

All the best

Rujing Zha

2014-06-20

charujing123

发件人：Douglas Greve <greve@nmr.mgh.harvard.edu>

发送时间：2014-06-20 16:51

主题：Re: [Freesurfer] some questions about optseq

收件人："freesurfer"<freesurfer@nmr.mgh.harvard.edu>

抄送：

I don't understand what you are trying to do. Can you elaborate? There is no way to make optseq produce a sequence where two events always occur in a certain order

On 6/20/14 4:27 AM, charujing123 wrote:

Hi FS experts,

I try to design the schedule by optseq2. However it is beyond my ability as our experiment has a little complicated.

Here is our goal:

two successive trials decide condition. For example, this is our sequence:2 2 1 1 2 2 2 1 1 2 2 1 2 1 1 2 1 2 2 1 1 1 1 2 2 2 2 1 1 1 2 1 2 1 1 1 1 1 1 2 1 2 1 2 1 2 1 2 2 1 1 2 2 2 2 2 2 1 1 1 2 2 2 1 2 2 2 2 1 2 2 1 1 2 1 1 2 1 1 1 2
.22 and 11 is the same condition(this condition has 40 repeats); 12 and 21 is the same condition(this condition also has 40 repeats). That is to say, there are two conditons in this run. 81 trials in this run, and each trial has 1.5s intervels. And mean intertrial intervals is 3.5s. Our TR is 2s.

According the efficiency about these two conditions, how could I design the intertrial intervals to get a appropriate sequence?

I tried this:

optseq2 --ntp 203 --tr 2 --psdwin 0 20 --ev ev1 2 40 --ev ev2 2 40 --nkeep 2 --o ex2 --nsearch 1000

Although it echo a result, I know, it is not what I need, because of every condition having two trials. So how I complete that?

Thanks.

All the best.

Rujing Zha

2014-06-20

charujing123
_______________________________________________
Freesurfer mailing list
Freesurfer@nmr.mgh.harvard.edu
https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer