Human motivation has been studied for decades, primarily in an attempt to answer a question: what drives us to take one action over another? Now, a team of researchers from the National Institutes of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health (NIH) has concluded that hunger is an even more powerful trigger than fear, thirst, anxiety or need. social.
The experts carried out a series of experiments with mice in which they evaluated a variety of motivational states, including hunger, fear, anxiety or thirst. For the study, they used the technique of optogenetics – which uses light to control neurons – to direct the peptide nerve cells in the brain, associated with AgRP neurons (the neurons that regulate appetite and are crucial for survival).
Hunger and thirst
In one of the experiments, the scientists either starved the rodents for 24 hours or activated their AgRP neurons in order to make them want to eat. The same mice were deprived of water. Another third group of mice was used as a control group deprived of water but not food.
When presented with both food and water, the mice, who were equally thirsty and hungry, opted for food over water, while the control group chose water. This indicates that hunger is a stronger motivating force than thirst.
Hunger and fear
In another experiment, researchers induced hunger in mice by activating AgRP neurons, before exposing them to a chamber scented with a chemical produced by foxes, an environment that triggers anxiety and fear in rodents.
When food was introduced into this scenario where the “fear” smell was coming from, the hungry mice overcame their fear in order to get the food, while the non-hungry control group mice chose to stay in the “safe” areas. and take no chances, suggesting that hunger trumps fear and anxiety as a motivating force.
Hunger and social needs
One more experiment revealed that hunger is also a greater motivation than social needs. Thus, the activation of AgRP neurons led the socially isolated mice to opt for a food contained in an adjoining enclosure instead of going to the adjoining enclosure in which there was another mouse. In the control group, the opposite happened.
Interestingly, brain activity increased when another mouse was near food, suggesting that AgRP neurons respond to potential competition for food.
“We believe that the presence of another mouse could be seen as a competitor for limited resources, that is, an increase in motivation to search for food, which represents a finding that no study has indicated so far,” explains Michael J. Krashes. , study leader.
The researchers believe that these results shed light on how animals and humans have evolved : “Our continued existence, together with that of other species, has motivated us to follow a series of behaviors, all governed by our nervous system,” he concludes. Krashes
The study has been published in the journal Neuron.
