The (neuro)science of getting and staying motivated

It’s really nice when something that I have been bleating on about for some time on the basis of the confluence of unconnected studies is finally proved to be right! A pat on the head is deserved.

There is no question that motivation is one of the hardest and yet important factors in life. It's the difference between success and failure, goal setting and aimlessness, well-being and unhappiness. And yet, why is it so hard to get motivated—or even if we do, to keep it up?

That is the question that scientists have long sought to answer—because not everyone listens to me.  Now a team of researchers have looked anew at the subject. They worked off previous knowledge that told them two things: First, that people differ a lot in their capacity to engage in motivated behavior and that motivational problems like apathy are common in neurodegenerative and psychiatric disorders. Second, to target an area of the brain called the "nucleus accumbens.”

Sitting close to the bottom of brain, the nucleus accumbens has been the subject of extensive research. The reason is that it was quickly found to be a major player in functions like aversion, reward, reinforcement, and motivation. It’s also a crucial part of the brain’s reward system.

To test and quantify motivation, the team designed what is known as a "monetary incentive force task". The idea is that participants perform a task with increasing—and measurable—effort and get paid sums of money that correspond to their effort. Basically, do more and get paid more.

In this study, 43 men were scanned to measure metabolites (small molecules) in the nucleus accumbens in their brains with a sophisticated brain-imaging technique called "proton magnetic resonance spectroscopy", or 1H-MRS. This can specifically measure the abundance of neurochemicals in the brain, such as neurotransmitters and metabolites. An 1H-MRS is often used in clinical settings to determine neurological disorders.

Subsequently, each participant was asked to squeeze a device that measures force—a dynamometer—to a given level of contraction in order to earn either 0.2, 0.5, or 1 Swiss franc (because they were Swiss researchers). This procedure was repeated 120 consecutive times, which made performance in the task quite demanding (and, I think, incredibly boring).

The idea of the experiment was that the increasing reward would motivate participants to invest energy in continuing the task. The scientists ran the experiment under isolation and group conditions to investigate the influence of competition on performance.

Once they had gathered the behavioral data, the researchers processed it through a computational model that allowed them to assess whether particular neurotransmitter levels found in the NA before the task predicted specific motivational outcomes.

The analysis revealed that the key to performance—and, by extension, motivation—lies in the ratio of two neurotransmitters in the nucleus accumbens: glutamine and glutamate (glutamate is one of the three most powerful reward neurochemicals). Specifically, the ratio of glutamine to glutamate dictates our capacity to maintain motivation and performance over a long period of time—what is referred to as "stamina".

Another discovery was that competition seems to boost performance even from the beginning of the task. This was especially the case for individuals with low glutamine-to-glutamate ratios in the nucleus accumbens.

What the researchers say: "The findings provide novel insights in the field of motivation neuroscience," said the lead researcher. "They show that the balance between glutamine and glutamate can help predict specific, computational components of motivated performance. Our approach and data can also help us develop therapeutic strategies, including nutritional interventions, that address deficits in effort engagement by targeting metabolism."

So, what? Quite a few moons ago it was discovered that people were more open to persuasion, were more motivated to collaborate, soon after they had eaten. This was confirmed by subsequent research. Soon after there was other research indicating that glutamate was one of the main reward neurochemicals (along with dopamine and oxytocin) with its own reward pathway. Glutamine is a precursor of glutamate and another ubiquitous neurochemical GABA. So the ratio of glutamine to glutamate tells us how much glutamine is left to be converted into the reward neurotransmitter glutamate—thus how enduring the motivation will be.

What this research seems to show is that people become motivated to use their supply of glutamate to energize them to perform at a higher level if there is another, extrinsic, reward (money in this case) offered. I assume that the effort would’ve been even greater if an intrinsic, relational, reward had been offered such as praise by someone important to them.

But since glutamate and glutamine are connected with food, a snack beforehand might’ve had a similar effect—if they’d wanted to perform the task in the first place.

The relationship of competition to performance, I suspect, has nothing to do with glutamate. Rather I believe it has more to do with testosterone—especially as all the study subjects were male. In the real world this might lead to improved individual performance and worse team performance.