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Elbau_et_al_PNAS_2018/README.txt
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Data repository for study | |
Elbau et al. The hemodynamic response function rapidly changes under psychosocial | |
stress in association with genetic and endocrine stress response markers. PNAS, | |
accepted 08/2018 | |
The repository contains the following 8 file types: | |
[1] First level models of the original (N=59, | |
comprising 39 experimental and 20 control subjects) and the replication | |
sample (N=39) (only experimental runs). | |
[2] Two key scripts that allow to calculate (a) the HRF-PL values | |
according to Henson et al. 2002 and (b) lag-corrected amplitude | |
values according to Calhoun et al. 2003. Note that prior to | |
statistical analyses these files were spatially smoothed. | |
[3] Two scripts destination.m and hrf_generation.m that make | |
the generation of the sigmoid transformation function transparent. | |
The script hrf_generation.m compares different beta2/beta1 ratios | |
against the empirically caused shift of the HRF peak when both | |
the canonical and the (orthogonalized) first derivative are | |
added. The resulting function may be newly produced and stored, | |
yet is also directly provided as file [4] = destination.mat. | |
Note that the script relies on the function spm_hrf.m | |
(in the version of SPM8). | |
The script destination.m optimizes C and D within certain | |
ranges, after it was noted that the original values of C =1.78 | |
and D = 3.10 (Henson et al. 2002) showed deviations from the | |
goldstandard. The error was already minimal by values C = -2 and | |
D = -0.9, yet the plot was then systematically shifted, particularly | |
in the y-direction. Thus, two correction coefficients were | |
introduced to correct for this shift. The eventually used | |
values were: C = -2, D = -0.7, Xcorr = 0.25, Ycorr = -0.5. | |
[5] The file destination.mat as explained in [3]. | |
[6] All MNI space transformed and discretized anatomical parcellations | |
(FreeSurfer, see methods) to allow for regional value extraction. | |
Files are labelled 'rwfsl_atlas_clean.img'. They are in the folders 'T1WI' (original sample) or 'mri' respectively. | |
[7] The background image used for result depiction, generated from | |
a mean image of all DARTEL normalized T1 images, combined with a | |
transparent overlay. The latter was defined (as specified in the | |
paper) from a combination of three F contrasts on the lag-corrected | |
amplitude effects. | |
[8] Cortisol data per subject (original sample) | |
Questions on this material may be directed to | |
immanuel_elbau@psych.mpg.de or saemann@psych.mpg.de | |
30th August 2018 |