Emily Hollenbeck lived with a deep, recurring depression she likened to a black hole, where gravity felt so strong and her limbs so heavy she could barely move. She knew the illness could kill her. Both of her parents had taken their lives.

She was willing to try something extreme: Having electrodes implanted in her brain as part of an experimental therapy.

Researchers say the treatment —- called deep brain stimulation, or DBS — could eventually help many of the nearly 3 million Americans like her with depression that resists other treatments. It’s approved for conditions such as Parkinson’s disease and epilepsy, and many doctors and patients hope it will become more widely available for depression soon.

The electrodes are connected by an internal wire to a device placed under the skin in her chest, which controls the amount of electrical stimulation and delivers constant low-voltage pulses. Hollenbeck calls it “continous Prozac.”

Doctors say the stimulation helps because electricity speaks the brain’s language. Neurons communicate using electrical and chemical signals.

Hollenbeck said the effect was almost immediate.

“The first day after surgery, she started feeling a lifting of that negative mood, of the heaviness,” said her psychiatrist, Dr. Martijn Figee. “I remember her telling me that she was able to enjoy Vietnamese takeout for the first time in years and really taste the food. She started to decorate her home, which had been completely empty since she moved to New York.”