Aversion is the opposite of reward and serves an important function in making us avoid things that make us feel bad. It is known in humans that strong activation of the aversion system in the brain can lead to depression.
This is where aversion arises
In a new study, researchers discovered where aversion originates in the brain. They have identified neuronal circuits that originate from the brain’s hypothalamus and connect directly to the brain’s emotional system, which is active during strong feelings of discomfort.
That the thalamus leads to aversion and avoidance behavior is an important finding, says Asa McKenzie, professor of molecular physiology at Uppsala University.
On the one hand, it increases our understanding of the brain’s emotional system and how brain activity can lead to psychological symptoms such as depression and apathy. This could provide a partial explanation for why people with Parkinson’s disease who are treated with deep brain stimulation, or DBS, experience these kinds of side effects, says Asa McKenzie.
DBS, brain electrodes
DBS is an abbreviation for “deep brain stimulation”, that is, deep brain stimulation. The method involves surgically inserting electrodes into the brain. With the help of these devices, incorrect nerve signals can then be blocked. Some people with Parkinson’s disease can be treated with deep brain stimulation (DBS), and among the symptoms that can be affected are tremors, slow movements, stiffness, dystonia, and pain.
DBS can also be used to treat obsessive-compulsive disorder, essential tremor, and rhythmic tremor of the body, among others.
Sources: Academic Hospital, Neuro.se And Norland University Hospital.
That could explain the side effects
In Parkinson’s disease, the hypothalamus is overactive, but by stimulating this brain area in seriously ill Parkinson’s patients using deep brain stimulation, see truth box above, this is “corrected” and patients get rid of tremors and other motor problems.
Treatment often works very well. However, some patients experience side effects, such as severe depression.
– Now that we have been able to show that the subthalamic nucleus has a direct relationship with aversion and is connected to the depression center in the brain, we can understand and explain these side effects in neurobiological terms, says Asa McKenzie.
So the study was done
To stimulate only the so-called subthalamic nucleus and not other brain tissue, the researchers used what is called optogenetics. This method relies on using a specific type of light to activate or deactivate individual neurons in the brains of genetically modified mice, whose neurons contain light-sensitive proteins on their surfaces. In previous studies, the researchers identified the markers used in the new study to distinguish the thalamus from surrounding structures with high accuracy. With this, they were able to study how individual neural circuits in the brains of mice are affected and how mice behave when neurons are more or less active.
Source: Uppsala University
It may improve treatment
This study is basic research that could, in the long term, improve the accuracy of DBS treatments, says Asa McKenzie.
The goal is for DBS to be able to treat the symptoms of the disease without causing severe side effects.
Read alsoTime perception can detect dementia
Scientific material:
A role for the subthalamic nucleus in aversive learning, Cell reports.
communication:
Asa McKenzie, Professor at the Department of Organismal Biology, Uppsala University
[email protected]
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