Do you like high-calorie foods? It may be because of your brain. Scientists discovered that the brain prefers caloric food due to the need for energy storage.
In previous studies, researchers found that circuits in the striatum and the dopaminergic neurons that enervate a certain brain region could be involved in recognizing value and taste. Striatal dopaminergic neurons express dopamine, which is associated with pleasure and reward. Until now, though, researchers weren't sure whether the circuits in the dorsal and ventral parts of the striatum were equally involved in recognizing these two characteristics.
In order to determine which neural circuits in the striatum are involved in the perception of the caloric attributes of food, scientists performed an experiment. This particular experiment was designed to quantify the expression of dopamine in the striata of mice after exposure to sweet substances with and without calories.
The mice were given a dipper bottle containing sweetener. When they licked the spout of the bottle, they received stomach injections of solutions containing sugar (D-glucose) or an equal amount of non-caloric sweetener (sucralose).
The results of the experiment showed that the amount of dopamine released by the ventral striatum increased indiscriminately in response to the intake of both sugar and sweetener. The neural circuits in the ventral striatum actually don't distinguish between caloric and non-caloric ingestion. Dopamine is expressed by this brain region in response to mere palatability.
The researchers also looked at the effect of an unpalatable but caloric substance on the expression of dopamine in the brain regions of the mice. They altered the taste of the sweetener by adding a bitter compound.
So what happened? The alteration in the taste inhibited dopamine released in the ventral striatum. However, the amount of dopamine expressed in the dorsal striatum increased. This could mean that if you have a "sweet tooth," it could be due to your brain craving calories rather than an addiction to sweetness itself.
The findings reveal how the brain tells the body that it needs calories. More specifically, it shows that some creatures prefer more caloric foods that don't taste as good to tastier foods that are less caloric.
The findings were published in the March journal Nature Neuroscience.
