Hi all,
I’m working on a project that is already well into data collection, and I’ve realized the task we are using doesn’t appear to be optimized for fmri. My understanding is the task was given to us from another lab - I assume what happened is that the task given was meant as a behavioral study and our lab implemented it without realizing the timing wasn’t intended for fmri. I have been tasked with determining whether the data are usable, or if we need to throw out the subjects we’ve collected and start with a new version of the task.
The stimuli of interest last for 1.3 seconds, with an ISI of .4 seconds - meaning the onset of each stimulus is separated by 1.7 seconds (timing table below). It is a 2 x 3 design, so there are 6 stimulus types, each presented 24 times.
I ran the timing through afni’s 3ddeconvolve with the -nodata option, an option which is used to test task efficiency. I was expecting 3ddeconvolve to throw multicollinearity errors, but it didn’t. 3ddeconvolve gives a normalized standard deviation for each regressor (for which I am getting: Neg_Int: .2952, Neu_Int: .3237, Post_Int: 3.094, Neg_NonInt: .3232, Neu_NonInt: .3232, Pos_NonInt: .2901). My understanding is that these values describe how correlated each regressor is with the other regressors in the design matrix, so the smaller the better. However, there is not standard for how small they should be, instead they are useful comparing one design against another.
My question is how should I be thinking about how to determine if this task timing is good enough to expect that the conditions could be deconvolved well enough to give useful results? Is there some tool other the 3ddeconvolve -nodata, that can give me insights into the task efficiency? Should I just assume that since the task hasn’t been designed properly, it isn’t worth trying to see it through to the end of the study? Or should I analyze the subjects we have, and if we are seeing activation that makes sense, assume that the task is ok?
Thanks!
| trial_type | onset | duration |
|---|---|---|
| Pos_NonInt | 0.4 | 1.3 |
| Pos_NonInt | 2.099 | 1.3 |
| Neu_Int | 3.798 | 1.3 |
| Neu_Int | 5.496 | 1.3 |
| Neg_Int | 7.195 | 1.3 |
| Pos_NonInt | 8.91 | 1.3 |
| Pos_NonInt | 10.592 | 1.3 |
| Pos_NonInt | 12.29 | 1.3 |
| Pos_NonInt | 13.989 | 1.3 |
| Neu_NonInt | 15.687 | 1.3 |
| Neg_Int | 17.386 | 1.3 |
| Neu_NonInt | 19.101 | 1.3 |
| Neu_Int | 20.799 | 1.3 |
| Pos_NonInt | 22.498 | 1.3 |
| Neg_NonInt | 24.196 | 1.3 |
| Neu_Int | 25.895 | 1.3 |
| Neu_NonInt | 27.593 | 1.3 |
| Neg_NonInt | 29.292 | 1.3 |
| Neg_NonInt | 30.99 | 1.3 |
| Neu_NonInt | 32.689 | 1.3 |
| Neu_NonInt | 34.387 | 1.3 |
| Neu_NonInt | 36.086 | 1.3 |
| Neg_Int | 37.801 | 1.3 |
| Neu_NonInt | 39.5 | 1.3 |
| Pos_Int | 41.198 | 1.3 |
| Pos_Int | 42.897 | 1.3 |
| Pos_NonInt | 44.595 | 1.3 |
| Neg_Int | 46.294 | 1.3 |
| Neg_NonInt | 48.009 | 1.3 |
| Neg_Int | 49.691 | 1.3 |
| Neu_NonInt | 51.389 | 1.3 |
| Neg_Int | 53.088 | 1.3 |
| Neu_NonInt | 54.786 | 1.3 |
| Pos_Int | 56.502 | 1.3 |
| Neu_NonInt | 58.2 | 1.3 |
| Neu_NonInt | 59.899 | 1.3 |
| Neu_Int | 61.597 | 1.3 |
| Pos_Int | 63.296 | 1.3 |
| Pos_NonInt | 64.994 | 1.3 |
| Pos_NonInt | 66.709 | 1.3 |
| Neg_Int | 68.391 | 1.3 |
| Neg_Int | 70.09 | 1.3 |
| Neg_Int | 71.788 | 1.3 |
| Pos_Int | 73.487 | 1.3 |
| Pos_Int | 75.185 | 1.3 |
| Pos_NonInt | 76.9 | 1.3 |
| Neu_Int | 78.599 | 1.3 |
| Neu_NonInt | 80.297 | 1.3 |
| Neu_Int | 81.996 | 1.3 |
| Neu_NonInt | 83.694 | 1.3 |
| Pos_Int | 85.41 | 1.3 |
| Pos_Int | 87.091 | 1.3 |
| Pos_NonInt | 88.79 | 1.3 |
| Neg_NonInt | 90.489 | 1.3 |
| Pos_Int | 92.187 | 1.3 |
| Neu_Int | 93.886 | 1.3 |
| Neu_NonInt | 95.601 | 1.3 |
| Neu_Int | 97.299 | 1.3 |
| Neu_NonInt | 98.998 | 1.3 |
| Neu_NonInt | 100.696 | 1.3 |
| Neu_Int | 102.395 | 1.3 |
| Pos_Int | 104.093 | 1.3 |
| Neg_NonInt | 105.792 | 1.3 |
| Neg_Int | 107.49 | 1.3 |
| Neg_Int | 109.189 | 1.3 |
| Neg_Int | 110.887 | 1.3 |
| Neu_Int | 112.586 | 1.3 |
| Neu_Int | 114.301 | 1.3 |
| Neg_NonInt | 116 | 1.3 |
| Neu_Int | 117.698 | 1.3 |
| Pos_NonInt | 119.397 | 1.3 |
| Neu_NonInt | 121.095 | 1.3 |
| Neg_NonInt | 122.794 | 1.3 |
| Neg_Int | 124.509 | 1.3 |
| Neu_Int | 126.191 | 1.3 |
| Neg_NonInt | 127.889 | 1.3 |
| Pos_NonInt | 129.588 | 1.3 |
| Neg_Int | 131.286 | 1.3 |
| Neu_Int | 133.001 | 1.3 |
| Neg_NonInt | 134.7 | 1.3 |
| Neu_NonInt | 136.398 | 1.3 |
| Pos_Int | 138.097 | 1.3 |
| Neg_NonInt | 139.795 | 1.3 |
| Pos_NonInt | 141.494 | 1.3 |
| Neg_NonInt | 143.209 | 1.3 |
| Neg_Int | 144.891 | 1.3 |
| Pos_NonInt | 146.59 | 1.3 |
| Neg_NonInt | 148.288 | 1.3 |
| Neu_Int | 149.987 | 1.3 |
| Neg_NonInt | 151.685 | 1.3 |
| Pos_Int | 153.4 | 1.3 |
| Pos_Int | 155.099 | 1.3 |
| Pos_Int | 156.797 | 1.3 |
| Pos_Int | 158.496 | 1.3 |
| Neg_Int | 160.194 | 1.3 |
| Neg_Int | 161.909 | 1.3 |
| Neg_Int | 163.591 | 1.3 |
| Pos_Int | 165.29 | 1.3 |
| Neu_Int | 166.988 | 1.3 |
| Pos_Int | 168.687 | 1.3 |
| Pos_NonInt | 170.385 | 1.3 |
| Pos_NonInt | 172.101 | 1.3 |
| Pos_NonInt | 173.799 | 1.3 |
| Neu_Int | 175.498 | 1.3 |
| Pos_NonInt | 177.196 | 1.3 |
| Neu_Int | 178.895 | 1.3 |
| Neu_NonInt | 180.593 | 1.3 |
| Neg_NonInt | 182.292 | 1.3 |
| Neu_NonInt | 183.99 | 1.3 |
| Neg_NonInt | 185.689 | 1.3 |
| Neu_Int | 187.387 | 1.3 |
| Neg_NonInt | 189.086 | 1.3 |
| Neg_NonInt | 190.801 | 1.3 |
| Pos_NonInt | 192.499 | 1.3 |
| Neg_NonInt | 194.198 | 1.3 |
| Neu_Int | 195.896 | 1.3 |
| Neu_NonInt | 197.595 | 1.3 |
| Neg_Int | 199.294 | 1.3 |
| Neg_Int | 201.009 | 1.3 |
| Neu_Int | 202.691 | 1.3 |
| Neu_NonInt | 204.389 | 1.3 |
| Pos_Int | 206.088 | 1.3 |
| Neg_NonInt | 207.786 | 1.3 |
| Pos_Int | 209.501 | 1.3 |
| Neu_NonInt | 211.2 | 1.3 |
| Neu_Int | 212.898 | 1.3 |
| Pos_Int | 214.597 | 1.3 |
| Neg_NonInt | 216.295 | 1.3 |
| Pos_Int | 217.994 | 1.3 |
| Neg_Int | 219.709 | 1.3 |
| Pos_Int | 221.391 | 1.3 |
| Pos_NonInt | 223.089 | 1.3 |
| Pos_Int | 224.788 | 1.3 |
| Neu_NonInt | 226.486 | 1.3 |
| Neu_Int | 228.185 | 1.3 |
| Neg_NonInt | 229.9 | 1.3 |
| Pos_NonInt | 231.599 | 1.3 |
| Neg_NonInt | 233.297 | 1.3 |
| Neg_Int | 234.996 | 1.3 |
| Pos_Int | 236.694 | 1.3 |
| Neg_Int | 238.409 | 1.3 |
| Pos_NonInt | 240.091 | 1.3 |
| Neg_NonInt | 241.79 | 1.3 |
| Neg_Int | 243.488 | 1.3 |