Question for the 3dresample and 3dLMEr

Hello. I have a question for the resampling.

As background, we have a dot probe task with 3 groups (SR/DP/HC) and 3 (DL: death/life/neutral) X 3 (CON: congruent/incongruent/neutral) conditions. By using the SPM, we specified nifti files in each condition (like 5 nifti files in each individual because the neutral conditions are overlapped; deathXcongruent, deathXincongruent, lifeXcongruent, lifeXincongruent, and neutral).

After the preprocessing using SPM, I resampled the individual imaging files using the structure atlas (T1 in MNI_N27). In addition, for the 3dLMEr analysis, I changed format of the brainmask (brainmask.nii.gz in MNI_N27), from nifti to afni, and its atlas. Then, I ran the 3dLMEr model estimation, including age as covariate.

The code is shown below:

3dresample -input ffespmeeg_111_sdotprobe-f_1_t0_1000_f30_58_1.nii -master T1.nii.gz -prefix ffespmeeg_111_sdotprobe-f_1_t0_1000_f30_58_1_resampled.nii

3dcopy brainmask.nii.gz MNI_N27_mask

3drefit -view tlrc MNI_N27_mask_orig

3dLMEr -prefix  XXX \
-resid XXX \ 
-model 'Group*Cond1*Cond2+Age+(1|Subj)+(1|Subj:Group)'	\
-qVars 'Age'	\
-SS_type 3	\
-bounds -2 2\
-gltCode Cong_Con_S 'Cond2 : 1*con Group : 1*SR Age :'		\
-gltCode Cong_Con_D 'Cond2 : 1*con Group : 1*DP Age :'		\
-gltCode Cong_Con_HC 'Cond2 : 1*con Group : 1*HC Age :'		\
-gltCode Cong_INCon_S 'Cond2 : 1*incon Group : 1*SR Age :'	\
-gltCode Cong_INCon_D 'Cond2 : 1*incon Group : 1*DP Age :'	\
-gltCode Cong_INCon_HC 'Cond2 : 1*incon Group : 1*HC Age :'	\
-gltCode Cong_Neu_S 'Cond2 : 1*neut Group : 1*SR Age :'		\
-gltCode Cong_Neu_D 'Cond2 : 1*neut Group : 1*DP Age :'		\
-gltCode Cong_Neu_HC 'Cond2 : 1*neut Group : 1*HC Age :'	\
-gltCode DL_Death_S 'Cond1 : 1*death Group : 1*SR Age :'	\
-gltCode DL_Death_D 'Cond1 : 1*death Group : 1*DP Age :'	\
-gltCode DL_Death_HC 'Cond1 : 1*death Group : 1*HC Age :'	\
-gltCode DL_Life_S 'Cond1 : 1*life Group : 1*SR Age :'		\
-gltCode DL_Life_D 'Cond1 : 1*life Group : 1*DP Age :'		\
-gltCode DL_Life_HC 'Cond1 : 1*life Group : 1*HC Age :'		\
-mask MNI_N27_mask+tlrc		\
-jobs 16		\
-dataTable		\
Subj	Group	Cond1	Cond2	Age	InputFile	\
111	SR	death	con	29.2	ffespmeeg_111_sdotprobe-f_1_t0_1000_f30_58_1_resampled.nii	\
111	SR	life	con	29.2	ffespmeeg_111_sdotprobe-f_1_t0_1000_f30_58_3_resampled.nii	\
111	SR	death	incon	29.2	ffespmeeg_111_sdotprobe-f_1_t0_1000_f30_58_2_resampled.nii	\
111	SR	life	incon	29.2	ffespmeeg_111_sdotprobe-f_1_t0_1000_f30_58_4_resampled.nii	\
111	SR	neut	neut	29.2	ffespmeeg_111_sdotprobe-f_1_t0_1000_f30_58_5_resampled.nii	\
112	SR	death	con	21.7	ffespmeeg_112_sdotprobe-f_1_t0_1000_f30_58_1_resampled.nii	\
112	SR	life	con	21.7	ffespmeeg_112_sdotprobe-f_1_t0_1000_f30_58_3_resampled.nii	\
112	SR	death	incon	21.7	ffespmeeg_112_sdotprobe-f_1_t0_1000_f30_58_2_resampled.nii	\
112	SR	life	incon	21.7	ffespmeeg_112_sdotprobe-f_1_t0_1000_f30_58_4_resampled.nii	\
112	SR	neut	neut	21.7	ffespmeeg_112_sdotprobe-f_1_t0_1000_f30_58_5_resampled.nii	\
113	SR	death	con	23.6	ffespmeeg_113_sdotprobe-f_1_t0_1000_f30_58_1_resampled.nii	\
113	SR	life	con	23.6	ffespmeeg_113_sdotprobe-f_1_t0_1000_f30_58_3_resampled.nii	\

...

After the resampling, there was a huge computational demand, which is probably because the increased voxel frequencies in the resampled individual data.

My questions are:

  1. Do you think my code seems adequate?
  2. How can I deal with a huge computational overloading after the resampling?
  3. I am wondering what if I resample the reference file (e.g., T1.nii.gz) using the individual file (opposite approach) rather than resampling the individual files using the reference file. Would it be different?

I appreciate your consideration in advance.

Do you think my code seems adequate?

Consider

-model 'Group*Cond1*Cond2*Age+(1|Subj)+(1|Subj:Cond1)+(1|Subj:Cond2)'	\

Do the groups have have similar average age? Check this document, and consider centering.

How can I deal with a huge computational overloading after the resampling?

If the input data are in high resolution, it is advisable to resample them to match the original EPI resolution. Contrary to common practice, higher resolution does not necessarily yield improvements in terms of statistical inference.

Gang Chen

1 Like

Thank you so much for the clarifying comments.