Only a small portion of that study has considered the issue of metabolism.
In life, motivation can mean the difference between happiness and misery, achievement and failure, goal-setting and aimlessness. The hardest part of gaining and maintaining motivation, however, is frequently this; this issue has led to a great deal of research. Oxidative stress is a phenomenon caused by an imbalance between production and accumulation of oxygen reactive species (ROS) in cells and tissues and the ability of a biological system to detoxify these reactive products.
Do variations in brain metabolites have an impact on our ability to be motivated? inquires Carmen Sandi, a professor in the School of Life Sciences at EPFL. If so, may nutritional measures that impact metabolite levels be a successful means of enhancing motivated performance? A study that provides some initial insight into the solution to that question has just been published by Sandi’s team in collaboration with their colleagues from the Nestlé Institute of Health Sciences.
The nucleus accumbens, which is located deep inside the brain and is known to be important in controlling processes including motivation, reinforcement, aversion, and reward, was the area on which the researchers concentrated. The study’s premise was that because of its metabolism, the brain is constantly under oxidative stress, much like all other tissues in our body.
Cells produce a number of harmful waste products in the form of highly reactive chemicals collectively referred to as “oxidative species” as they “eat” various molecules for fuel. Naturally, cells have a number of processes in place to eliminate oxidative species and reestablish the chemical balance of the cell. However, this conflict persists, and occasionally the balance is upset. This disruption is what we refer to as “oxidative stress.”
The topic that the researchers wanted to know was if antioxidant levels in the nucleus accumbens can alter motivation because the brain is frequently subjected to excessive oxidative stress from its neurometabolic activities. The most significant antioxidant in the brain, glutathione (GSH), and its connection to motivation were examined by the researchers in order to provide an answer to their inquiry. According to Sandi, they looked at connections between metabolites in the nucleus accumbens, a significant brain area, and performance motivation.
The first method they employed was proton magnetic resonance spectroscopy, which is a non-invasive method of evaluating and quantifying the biochemistry in a particular area of the brain. To evaluate the amounts of GSH, the researchers used the procedure on the nucleus accumbens of both rats and humans.
The performance of their human and animal subjects in standardised, effort-related tests that gauge motivation was then compared to those levels.
They discovered that greater and more consistent performance in the incentive tasks was connected with higher GSH levels in the nucleus accumbens. The scientists continued with live tests using rats that received micro-injections of a GSH blocker, which downregulated the synthesis and levels of the antioxidant because correlation does not imply causality. Now, the rats had reduced motivation, as seen by their decreased performance in tests that rewarded effort.
Rats performed better when the researchers administered a nutritional intervention that included the GSH precursor N-acetylcysteine, which raised GSH levels in the nucleus accumbens. According to the scientists, the effect was possibly mediated by a cell-type-specific shift in glutamatergic inputs to accumbal medium spiny neurons.
Can dietary supplements or nutrition boost motivation? The authors write that their research “offers unique insights on the relationship between brain metabolism and behaviour and proposes nutritional therapies targeting key oxidative processes as suitable interventions to improve effortful endurance.” The results of the study indicate that enhancing accumbal antioxidant capacity may be a workable strategy to increase motivation.
The dietary supplement used in the study, N-acetylcysteine, can also be produced by the body from its precursor cysteine. Foods heavy in protein, like meat, poultry, fish, and seafood, contain cysteine. Eggs, whole-grain products like bread and cereal, and some vegetables like broccoli, onions, and legumes are additional sources with lower content.
Naturally, there are other ways besides N-acetylcysteine to raise GSH levels in the body, but little is known about how these other methods relate to GSH levels in the brain, namely in the nucleus accumbens. Their findings support the idea that dietary N-acetylcysteine can raise GSH levels in the brain and promote effortful behaviour, says the scientists.
Parvathy Sukumaran 
