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Happiness cannot be reduced to a messenger
Until now, scientists have assumed that the messenger substance dopamine plays a central role for happiness that is felt, since it is always distributed by the reward system when you are successful or happy about something. The latest research results now show that the process of happiness is apparently more complex than previously thought. In a series of experiments, scientists were able to show that dopamine only seems to play a minor role in happiness.
A research team led by Dr. Michael Lippert and PhD student Marta Brocka at the Leibniz Institute for Neurobiology (LIN) in Magdeburg investigated how well happiness can be measured. They assumed that happiness could be made visible by the dopamine release during an imaging procedure in an MRI scanner. During the test series, they came to surprising results, which were recently published in the specialist journal "Neurolmage".
What is happiness and what is not?
From a philosophical point of view, this is the main topic of countless books and films. The Magdeburg scientists want to understand the mechanisms that take place in the brain when one feels happiness. So far, the release of the neurotransmitter dopamine has been regarded as fundamental for feelings of happiness. However, the results of the study indicate that a rethink in this area is necessary.
The visibility of happiness
Patients with depression or addictions are known to experience changes in the brain's own reward system. So far, neuroscientists and doctors have used functional magnetic resonance imaging (fMRI) to make such changes visible. Lippert and his team checked whether this method is actually suitable for such purposes and whether happiness can be made visible in an MRI scanner.
Rats that are smiths of their “luck”
In the animal model, the LIN researchers carried out experiments on genetically modified rats. The rodents could control their dopamine release in the brain. By independently operating a lever, they received so-called optogenetic stimulation, in which light pulses in the brain stimulate the release of dopamine. "This creates an extremely strong reward stimulus," reports PhD student Marta Brocka in a press release on the study results.
Imaging procedures should provide information
Meanwhile, the animals were examined with a small animal scanner to document which areas of the brain were activated and how strongly as a result of the release. According to the researchers, the areas of the brain can be visualized with a high spatial resolution using imaging techniques. “When we take pictures in the tomograph, we see changes in the blood flow to areas of the brain,” explains Lippert. These would be based on metabolic processes, which in turn would be related to neuronal activity, said the brain expert.
Is the essence of happiness invisible?
In the course of the experiments, the team was surprised to find that “the measurable effects of dopamine were very small despite the high reward value of the stimulation”. In contrast, a comparison group, in which additional brain areas were stimulated, showed clearer results. The scientists come to the conclusion: "The release of dopamine on which the feelings of happiness are based cannot be measured directly in an MRI scanner." Instead, the overall activation of the brain area is decisive. The essence of happiness remains invisible with this method.
For whom are the results relevant?
According to the authors of the study, the results could have a decisive impact on further research projects, since it was previously assumed that dopamine in animals and humans had a major influence on the measured signals in the brain. "We have to say goodbye to the assumption that the changes in brain activity that we see as a reward are directly triggered by dopamine," says study leader Lippert.
The role of dopamine in change
The research results could also be of importance for the clinical area, since an imbalance in the dopamine level is also seen as a possible cause for diseases such as Parkinson's, addiction or depression. Another study recently appeared that focused on dopamine. It turned out that the fear memory is also regulated by the happiness hormone. (vb)