Scientists have laid bare a novel molecular mechanism responsible for the major depression symptom, anhedonia, the loss of the ability to experience pleasure. The brain circuit involved in this newly elucidated pathway is largely identical between rodents and humans, upping the odds that the findings point toward new therapies for depression and other disorders. Additionally, opinion leaders hailed the study’s inventive methodology, saying it may offer a much sounder approach to testing new antidepressants.