The premise of this proposal is that the clinical efficacy of lithium in bipolar disorder, and its complex effects on multiple brain physiological functions, may be best deciphered using a network properties-metric approach. This approach is critical because it provides insight into the function of brain networks (e.g., resilience to disruption, central hubs), which is likely to be more closely linked to behavioral outcomes. Furthermore, we will conduct an exploratory investigation of the in vivo molecular effects of lithium by measuring peripheral gene expression. To bring these together, we will also explore whether connectome changes serve as mediator between molecular changes (i.e., gene expression) induced by lithium treatment and behavioral changes (e.g., depression, mood stability, suicidality).