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Researchers have discovered a control mechanism for an area of the brain that processes sensory and emotive information that humans experience as 'disappointment,' according to a new study. 

"The idea that some people see the world as a glass half empty has a chemical basis in the brain," said senior author Roberto Malinow, MD, PhD, professor in the Department of Neurosciences and neurobiology section of the Division of Biological Sciences, in the press release. "What we have found is a process that may dampen the brain's sensitivity to negative life events."

The study findings might have implications for understanding the brain chemistry of people that predisposes them to depression. Experts believe the findings could also lead to a treatment of such conditions. 

"Our study is one of the first to rigorously document that inhibition can co-exist with excitation in a brain pathway," said lead author Steven Shabel, a postdoctoral researcher with Department of Neurosciences and neurobiology section of the Division of Biological Sciences, in the press release. "In our case, that pathway is believed to signal disappointment."

In experiments with rodents, researchers showed that neurons of rodents with aspects of human depression produced less GABA, relative to glutamate. When they were given antidepressant to raise their brain's serotonin levels, their relative GABA levels increased, according to the press release.

 "Our study suggests that one of the ways in which serotonin alleviates depression is by rebalancing the brain's processing of negative life events vis-à-vis the balance of glutamate and GABA in the habenula," Shabel said. "We may now have a precise neurochemical explanation for why antidepressants make some people more resilient to negative experiences."

The study has been published in the journal Science.