Control Spontaneous Dopamine Boosts

Researchers at UC San Diego have discovered that spontaneous impulses of dopamine occur in the brain of mice. Dopamine is the neurological messenger known as the brain's "feel good" chemical. The researchers have also found that mice can willfully manipulate these random dopamine pulses for reward.

"This started as a serendipitous finding by a talented, and curious, graduate student with intellectual support from a wonderful group of colleagues," says senior researcher David Kleinfeld in a press release issued by UC San Diego. "As an unanticipated result, we spent many long days expanding on the original study and of course performing control experiments to verify the claims. These led to the current conclusions."

Dopamine is a neurotransmitter that carries signals between brain cells. It is often described as the brain's "feel good" chemical related to reward and pleasure. Dopamine plays a major role in reward-motivated behavior.

The anticipation of most types of rewards increases the level of dopamine in the brain. And many addictive drugs increase dopamine. But rather than investigating the production of dopamine in the brain induced by external stimuli, the UC San Diego researchers investigated spontaneous production of dopamine in laboratory mice.

A study is published in Current Biology. It indicates that, in mice, the brain is flooded with unpredictable impulses of dopamine that occur approximately once per minute. Suitably designed tests revealed that the mice are aware of these dopamine impulses. And they learn to anticipate and control them up to a certain degree.

For example, in tests where a reward is received after spontaneous generation of dopamine impulses, the mice learned to reliably elicit these impulses. And these effects reverse when the reward is removed.

The researchers argue that “spontaneous dopamine impulses may serve as a salient cognitive event in behavioral planning.” And “an animal's sense of spontaneous dopamine impulses may motivate it to search and forage in the absence of known reward-predictive stimuli.” So far, dopamine appears to invigorate existing behaviors, rather than initiate new ones.

Further research will explore if and how unpredictable dopamine events drive foraging, mating, and social behaviors. According to the researchers, this study opens a new dimension in the study of dopamine and brain dynamics.

Though these research results have been obtained in experiments with laboratory mice, it seems plausible to me that similar mechanisms could be at work in humans. And further insights on the causes and effects of spontaneous “feel good” pulses could have an important impact on human well-being.