1. Potential roles for opioid receptors in motivation and major depressive disorder Charlotte K. Callaghan, Jennifer Rouine and Shane M. O'Mara 2. Opioid modulation of depression: A focus on imaging studies Jennifer Rouine, Charlotte K. Callaghan and Shane M. O'Mara 3. Modulation of the central opioid system as an antidepressant target in rodent models Kelly L. McHugh and John P. Kelly 4. Stress-induced modulation of pain: Role of the endogenous opioid system Mehnaz Ferdousi and David P. Finn 5. Opioid modulation of cognitive impairment in depression Moriah L. Jacobson, Hildegard A. Wulf, Caroline A. Browne and Irwin Lucki 6. Frontal cortex dysfunction as a target for remediation in opiate use disorder: Role in cognitive dysfunction and disordered reward systems Dominic Roberts, Andrew Wolfarth, Connie Sanchez and Alan L. Pehrson