Computational protocol: Single Session Low Frequency Left Dorsolateral Prefrontal Transcranial Magnetic Stimulation Changes Neurometabolite Relationships in Healthy Humans

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Protocol publication

[…] The FMRIB Software Library (FSL v. 4.1.9) was used to initially process the fMRI data used for this study (Smith et al., ; Woolrich et al., ; Jenkinson et al., ). Individual image processing (i.e., first level analysis) was performed in the same manner as described in Parker et al. () for activation and deactivation contrasts. This experimental setup was designed to isolate brain regions used during the encoding phase from the response phase of the SWMT. A second level repeated measures (fixed effects) analysis was used to take the differences between the contrast of parameter estimate (COPEs) images resulting from the initial analyses. The COPEs resulting from the second level analysis were then used as inputs into a third level paired t-test (mixed effects) to generate (Realpost − Realpre) > (Shampost − Shampre) and (Realpost − Realpre) < (Shampost − Shampre) contrasts. In a separate post hoc analysis, paired t-tests comparing activation maps before and after stimulation were carried out to generate the following contrasts: Realpost > Realpre, Realpost < Realpre, Shampost > Shampre and Shampost < Shampre (mixed effects). All above mixed effects analyses used FSL’s “flame 1 + 2” option with de-weighted outliers and were registered to a MNI-152 standard 2 mm atlas. [...] The PickAtlas software toolbox (Maldjian et al., , ) was used to generate a mask for the left DLPFC based on structures from the Talairach Daemon (TD; Lancaster et al., , ) and Automated Anatomical Labeling (AAL) databases (Tzourio-Mazoyer et al., ). The mask was created by combining the following regions: the inferior and middle frontal gyri TD structures (John et al., ; Murray and Ranganath, ) and the pars opercularis and pars triangularis of the inferior frontal gyrus AAL structures (Eippert et al., ; Krueger et al., , ; Telzer et al., ). To finalize the mask, these structures were limited to those with MNI coordinates inferior to 40 mm and superior to 12 mm. Thresholded voxel z-statistic values, which were registered to a MNI-152 standard, were extracted using MATLAB (v. 2013a; Mathworks Inc., Natick, MA, USA) and analyzed using SAS (v. 9.2, Cary, NC, USA). A Z and cluster-P threshold of 2.3 and 0.05 were used respectively to identify active voxel clusters (i.e., voxel extent). The pre to post stimulation voxel extent change was correlated with RT as well as each metabolite ratio pre to post stimulation change for the sham and real stimulation conditions separately. […]

Pipeline specifications

Software tools FSL, AAL
Applications Magnetic resonance imaging, Functional magnetic resonance imaging
Organisms Homo sapiens