Learning How the Brain Sustains Motivation to Reach Long Term Goals

Ann Graybiel, Ph.D., expert in brain research
Ann Graybiel, Ph.D.

Researchers at the McGovern Institute for Brain Research at MIT led by NARSAD Distinguished Investigator Grantee, Ann Graybiel, Ph.D., have used a new technology to uncover how the brain concentrates to achieve long-term goals. In partnership with 2007 NARSAD Young Investigator Grantee, Paul Phillips, Ph.D., from the University of Washington, the team worked with animal models and used fast-scan cyclic voltammetry (FSCV) in which tiny, implanted, carbon-fiber electrodes allow continuous measurements of dopamine concentration. Their work was reported online August 4th in the journal Nature.

It is known that dopamine, a neurotransmitter in the brain, is connected to rewards―when an animal receives an unexpected reward, dopamine neurons show brief bursts of activity. This is believed to be important for reinforcement learning, where animals learn the behaviors that lead to rewards. In this new work, the research team wanted to see if and how dopamine changes during a task involving delayed gratification. To study this, they trained rats to navigate a maze to reach a reward and tracked the dopamine levels in their brains with FSCV.

The team found that the dopamine signals increased as the animals navigated to reach remote rewards. The level of dopamine increased steadily, peaking as the animal approached its goal―as if in anticipation of a reward. “The dopamine signal seems to reflect how far away the rat is from its goal,” Dr. Graybiel explains. “The closer it gets, the stronger the signal becomes.” The researchers also found that the size of the signal was related to the size of the expected reward: When rats were trained to anticipate a larger gulp of chocolate milk, the dopamine signal rose more steeply to a higher final concentration.

The researchers conclude that such prolonged dopamine signaling could provide sustained motivational drive, something that can be impaired in a range of neurologic and neuropsychiatric disorders.

Read more about this research.

Article comments

This seems to be about extrinsic motivation, as the rats' increased levels of dopamine appeared to be a function of expectation of a larger gulp of chocolate milk. How would this work to boost flagging intrinsic motivation in the face of challenging tasks?

I am so happy to see research headed in this direction. As someone who has chronic, treatment refractory depression that responds only to dopaminergic drugs (bupropion is the core of my regimen, with pregabalin an amazing recent addition to the mix) I have become very aware of how the main characteristic of my illness is lack of motivation, inability to anticipate pleasure/satisfaction from the ordinary activities that keep others going about their daily business. If I complete the activity, I may get that dopamine boost. But it does not seem to carry forward to promote future repeats. The anticipatory role is feeble.

The list of medications I have taken in my years of treatment goes on for pages. The SSRIs were worse than useless. On the other hand, medications whose on label use is for Parkinson's have been useful adjuncts. I have had more than one friend tell me their doctor has started them on Prozac. Then months later they called to tell me they have been switched to Wellbutrin and it was a life changer. Strictly anecdotal, but it is my firm belief that bupropion and other dopaminergic medications are under utilized, perhaps even should be considered first line, rather than something to try when SSRIs are ineffectual. Research like this could change the prevailing view of the root cause of depression in the majority of sufferers. Brava!

When you use dopamine blockers (especially dopa 2 and 3 receptors), what reports do you have regarding the goal reaching of LTG's?

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