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How the brain brings animals to a balanced eating behavior
Eating is, of course, a good thing in and of itself in order to maintain the health of the body and enable survival. However, eating too much can also have negative effects. Regulation is therefore important! Researchers have now found brain cells in animals that slow down their urge to eat.
A recent study by Rockefeller University identified cells in the brains of animals that can suppress the urge to eat in them. The cells also play an important role in regulating memory and promoting balanced eating behavior. The results of the study were published in the English-language journal "Neuron".
Mental processes determined the food intake of animals
When an animal sees or smells appealing food, it eats it immediately. This idea is not entirely true. The investigation indicated that mental processes influence the animals' decision whether to eat a meal or refuse it. In such a case, people might think, for example, that they will go to lunch in about 20 minutes anyway and therefore do not eat a meal beforehand so as not to spoil their appetite. While other mammals may not have the same internal monologue, there is reason to believe that their eating habits involve complex choices.
What role do hD2R neurons play?
Other studies have already shown that errors in the hippocampus, a part of the brain involved in memory, can change eating habits, which suggests that past experiences influence the attraction of food to an animal. Based on these results, the researchers recently identified a group of hippocampal cells known as hD2R neurons, which is active every time a mouse is fed. It was also found that mice ate less when these neurons were stimulated. When the neurons were deactivated, the animals ate more. In other words, the hD2R neurons respond to the presence of food by preventing animals from eating it.
Sometimes it is risky for animals to look for more food
Although animals usually benefit from eating the food in front of them, it is also helpful in some cases to exercise restraint. If, for example, an animal has already eaten enough, the further search for food would be both unnecessary and risky, since the search could make the animal the victim of a predator. The newly discovered neurons seem to help animals stop eating when they don't need more food. The discovered cells prevent an animal from eating too much, the researchers explain. They seem to make the feed less attractive and in this sense they control the behavior of the animals.
What did an activation of hDR2 do?
Animals cannot eat anything in the wild unless they know where to find food. Fortunately, their brains can remember the locations of previous meals well. When an animal encounters food in a particular area, it creates a mental connection between the place and the food. To test how hD2R cells could affect these connections, the researchers stimulated the neurons while mice roamed around in a food-filled environment. The stimulation made the animals less likely to return to the area where the food was previously. This suggests that activating hDR2 somehow reduces the memories associated with the meal.
Brain develops mechanisms to fine-tune appetite
Further experiments showed that hD2R neurons receive input from the entorhinal cortex, which processes sensory information and sends output to the septum, which is involved in food intake. The researchers who first identified this brain cycle concluded that the neurons act as a checkpoint between the detection of food and the consumption of food. Together with analysis of other neural circuits, these studies indicate that the brain is developing mechanisms to fine-tune appetite. While some systems help an animal remember to find food, others limit food intake. The study shows that areas of the brain involved in cognitive processing and memory formation influence eating behavior. This suggested that through training, people can learn to change their relationship with food, the research team concluded. (as)