To test our hypothesis of IFC underactivation, we reanalyzed the data at a more lenient p value of p <.002 for voxelwise comparison.
For massive-testing platforms, such as genome-wide association studies, it might be expected that many false-positive violations of HWE would occur if a lenient P value threshold were set.
To test our hypothesis that stimulants increase basal ganglia activation, which is more difficult to detect in fMRI due to their relatively small size, we explored the data using a more lenient p <.05.
All findings remained significant at a more lenient P-value (P < 0.03).
While using lenient P-value thresholds might well improve the overlap, it might also produce many false positives.
Therefore, we used a more lenient P-value threshold for prioritization and annotation of a set of 'promising' SNPs, reported estimates of variance explained by all GWAS SNPs and made available the complete set of our GWAS results.
Because of the small sample size, we used a lenient P-value of 0.01 as a threshold for our analysis and found 105, 59, and 89 QTTs associated with state 3, state 4, and P O ratio, respectively, in the analysis averaged across sexes (see Additional file 3).
Initially, a relatively lenient p-value (p ≤ 0.05) was set to detect voxels putatively demonstrating differences between groups and then searched for spatial clusters of such voxels and finally, tested the mass of each cluster (the sum of suprathreshold voxel statistics it comprises) for significance.
No significant interaction effects above the predefined statistical threshold were found, but at a more lenient threshold (p < 0.001 uncorrected at the voxel level, k ≥ 5), significantly higher activity at T1 was found for Rc-++ items in several bilateral frontal regions compared to Rc+++ items (see Fig. 2a, b).
This mask was created at lenient threshold (P < 0.05 corrected for multiple comparisons, covering 149 404 mm), so as to cover to the largest extent the visually-responsive cortex.
No activations were observed in any regions correlating with the variance of the "evidence" on the irrelevant dimension (UVi), although positive correlations with the irrelevant variance were observed in the visual cortex at very lenient thresholds (P < 0.005 uncorrected).
