I’m trying to analyze an experiment that used sparse temporal sampling on a Siemens Avanto 1.5T.
in the experiment, an auditory stimulus was presented in quiet and lasted 12s, after which subjects had 1.725s to make a response with a button box (also in quiet) and then one volume was collected (40 ascending slices, slice TA = 0.085s, total volume TA = 3.4s). So each trial started with 13.725s of stimulus/response followed by 3.4s in which we collected 40 slices. There are 105 trials/volumes.
I have a couple questions:
in the 3dinfo output (below) it looks like the number of time steps is correct (105 volumes) but the time step says 0.08500s, which is the single slice time step… does AFNI need this to be the volume TA? If so, how do I change it?
what basis function and timing parameters would you recommend for a design like this?
- 3dinfo: AFNI version=AFNI_16.2.06 (Jul 25 2016) [64-bit]
Dataset File: scan03+orig
Identifier Code: XYZ_XXqbt2BNhRb-R51FngpsmQ Creation Date: Thu Nov 3 20:24:12 2016
Template Space: ORIG
Dataset Type: Echo Planar (-epan)
Byte Order: LSB_FIRST [this CPU native = LSB_FIRST]
Storage Mode: BRIK
Storage Space: 34,406,400 (34 million [mega]) bytes
Geometry String: “MATRIX(3,0,0,-96,0,2.932248,0.633974,-105.5745,0,-0.633974,2.932248,-34.41222):64,64,40”
Data Axes Tilt: Oblique (12.200 deg. from plumb)
Data Axes Approximate Orientation:
first (x) = Right-to-Left
second (y) = Anterior-to-Posterior
third (z) = Inferior-to-Superior [-orient RAI]
R-to-L extent: -96.000 [R] -to- 93.000 [L] -step- 3.000 mm [ 64 voxels]
A-to-P extent: -92.566 [A] -to- 96.434 [P] -step- 3.000 mm [ 64 voxels]
I-to-S extent: -54.699 [I] -to- 62.301 [S] -step- 3.000 mm [ 40 voxels]
Number of time steps = 105 Time step = 0.08500s Origin = 0.00000s Number time-offset slices = 40 Thickness = 3.000
– At sub-brick #0 ‘#0’ datum type is short: 0 to 4095
– At sub-brick #1 ‘#1’ datum type is short: 0 to 4095
– At sub-brick #2 ‘#2’ datum type is short: 0 to 4095
** For info on all 105 sub-bricks, use ‘3dinfo -verb’ **
----- HISTORY -----
[firstname.lastname@example.org: Thu Nov 3 20:24:11 2016] to3d -prefix scan03 -time:zt 40 105 85 seqplus CAP_FRA.MR.UCL_BBK_KYLE.03.0001.2016.11.03.20.29.39.140625.650860832.IMA CAP_FRA.MR.UCL_BBK_KYLE.03.0002.2016.11.03.20.29.39.140625.650860870.IMA CAP_FRA.MR.UCL_BBK_KYLE.03.0003.2016.11.03.20.29.39.140625.650860908.IMA … CAP_FRA.MR.UCL_BBK_KYLE.03.0104.2016.11.03.20.29.39.140625.650865771.IMA CAP_FRA.MR.UCL_BBK_KYLE.03.0105.2016.11.03.20.29.39.140625.650865809.IMA