Mice overcome fear, depression with natural Prozac

By Maggie Fox, Health and Science Editor

WASHINGTON (Reuters) - The brain can produce antidepressants with the right signal, a finding that suggests that meditating, or going to your "happy place," truly works, scientists reported on Wednesday.

Mice forced to swim endlessly until they surrendered and just floated, waiting to drown, could be conditioned to regain their will to live when a tone they associated with safety was played.

The experiment suggests that there are good ways to teach people this skill, and points to new routes for developing better antidepressants, said Dr. Eric Kandel of the Howard Hughes Medical Institute and Columbia University in New York, who led the research.

"The happy place works. This is like going to the country," Kandel said in a telephone interview.

Writing in the journal Neuron, Kandel's team said they used classical conditioning to train mice. They had already conditioned some mice to fear a neutral tone by playing the sound when they shocked the animals' paws. After a while, the tone itself creates fear.

"It scares the hell out of the animal," Kandel said.

They decided to reverse the study -- they played the tone when they were not shocking the mice. "It learned that the only time it was really safe is when the tone comes on," Kandel said.

To make a mouse depressed, they used a method favored by drug companies called learned helplessness.