The results showed that voxel activity exclusively mediates the relationship bidirectionally between the AUDIT score and SSRT (Figure 4; Table 4). That is, the correlation between the AUDIT score and regional activity and that between regional activity and SSRT were both significant, and the correlation between the AUDIT score and SSRT was totally accounted for by regional brain activity (see Methods). In additional analyses, we investigated whether specific brain regions contribute to this mediation. Among the four clusters, the bilateral dACC/SFG, left MFG, and pre-SMA each mediated the relationship bidirectionally between the AUDIT score and SSRT (Models 1 and 2, Figure 4). On the other hand, neither SSRT nor the AUDIT score significantly mediated the correlation between voxel activity and the other variable (Models 3 and 4, Figure 4). In the remaining two models, there were not significant mediation effects.
