If effective, physical activity could become a first line of treatment for depression, which might also help reduce cognitive deficits, job productivity, and risk of other psychiatric conditions. Furthermore, although physical exercise has shown promise in reducing depressive symptoms, researchers still do not understand the biological pathways by which it works. One of the leading hypotheses of depression is that disruptions in GABA systems underlies the deficits. In contrast, improvements in GABA signaling is one of the ways in which exercise may improve brain function and reduce depressive symptoms. Along this line, investigators hope to determine the type of exercise (aerobic versus stretching and toning) that can be promoted in the future to improve brain function and reduce depressive symptoms. Demonstrating these links could be an important first step for developing more effective treatment plans for those suffering from depression.