"The human brain is like a black box. We have developed one more way to look inside and understand how these systems work..."

The loss of the so-called "happiness" chemical, serotonin, may contribute to memory problems, including Alzheimer's disease.

Researchers are working toward genetically engineered bacteria that monitor chemical production from inside a person's gut and fix any imbalances.

New research with mice clarifies how the brain creates new social memories, a process that involves the neurotransmitter serotonin.

"We've figured out how MDMA promotes social interaction and showed that's distinct from how it generates abuse potential among its users."

People with heightened somatic awareness "have discomforts...that doctors can't seem to find or see, but it's very real."

Serotonin helps the brain pick the right behavior in dangerous situations, research shows.