"Previous research on mice has shown that a brain protein called deltaFosB increases in response to stress."

"In the study, a team led by Eric Nestler, of the University of Texas Southwestern Medical Center at Dallas, exposed mice to random shocks from which the animals could not escape. Then they measured the lag time for the mice to escape subsequent shocks when they were given the chance to do so. This lag time represents the animals' level of "behavioral despair.""

"This experimental approach is often used to model human emotional disorders, including depression, post-traumatic stress disorder (PTSD) and bipolar disorder. Like humans with such disorders, behavioral despair in mice responds to antidepressants."

"The mice with the shortest lag time (i.e., the least despair) also had higher levels of deltaFosB in a brain region involved in processing
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