To examine whether the influence of structural damage on episodic memory capacity is mediated by functional connectivity, we conducted a mediation analysis using the Aroian test (Aroian, 1944). In short, the Aroian test examines whether the unstandardized regression coefficient between the independent variable (i.e., structural integrity) and the dependent variable (i.e., episodic memory scores) decreases significantly if the mediator variable (i.e., functional connectivity) is included in the prediction model. Specifically, we conducted a series of simple and multiple linear regressions 1. between brain scores from the GMV-VM/VSM-PLS and episodic memory scores, 2. between brain scores from the FC-VM/VSM-PLS and episodic memory scores, 3. between brain scores from the GMV-VM/VSM-PLS and FC-VM/VSM-PLS analyses, and 4. between both GMV-VM/VSM-PLS and FC-VM/VSM-PLS brain scores and episodic memory. We then entered the unstandardized regression coefficients and standard errors of regression analysis 3 and 4 into the Aroian test. We considered a decrease of the regression coefficients of p < 0.05 significant. Of note, both GMV- and FC-VM/VSM-PLS maximize the correlation between GMV or FC and episodic memory and it is therefore not surprising that
