Fear is an emotional response when the body faces a threat that may threaten survival. For organisms, the rapid and effective response to risky stimuli is the key to ensuring the survival and continuation of species. In the long-term evolution process, organisms tend to evolve adaptive action strategies when faced with different environments. When it is considered that the dangerous stimulus source can be controlled or evaded, the creature generally tends to adopt an active defense strategy, that is, escape behavior; and when the dangerous stimulus source is uncontrollable or evasive, it is more inclined to adopt a passive defense strategy. Such as freezing behavior.
How do animals make decisions when they face a fearful environment? Recently, Professor Li Xiaoming from the Medical College of Zhejiang University published a related research paper online in Nature-Neurology. The study has newly discovered a neural circuit from the cortex to the thalamus mediated by the thalamic reticular nucleus, which is involved in regulating the animal's fearful escape behavior. The study has a conceptual breakthrough in the circumcision of phobic escape behavior and related mental illnesses, such as the pathogenesis of post-traumatic stress disorder (PTSD), opening up new directions for research in this area.
Neural loop mechanism of fear behavior
In this study, the researchers first let the mice fear the sequence of sound signals consisting of pure and white noise, and the foot shocks were made at the end of the sequence of sound signals. After a period of training, the mouse will evade as soon as it hears the sequence. They then study how fear translates into behavioral output to reveal how fear is generated when the danger comes, and how the brain helps us make corresponding behavioral decisions to deal with threat stimuli.
Dong Ping, the first author of the thesis and a doctoral student at Zhejiang University School of Medicine, told the Journal of Chinese Academy of Sciences that the thalamic reticular nucleus (TRN) is a nucleus on the dorsal side of the thalamus, because there are many cortex and thalamus. The mutually projecting axon bundles pass through the nucleus, and the axon bundles form a network complex structure with the nucleus, and the "mesh" of the thalamic reticular nucleus is also derived therefrom. He pointed out: "The thalamic reticular nucleus is thought to play a 'gating' role in the brain, responsible for filtering and screening the exchange of information between the cortex and the thalamus, and is thought to play an important role in selective attention and sleep. However, the thalamus The correlation between the reticular nuclear subregion and its neural circuits and phobic escape is not clear."
In the study, they first discovered that the small albumin (PV)-positive GABA in the limbic nucleus of the thalamic reticular nucleus was associated with neuronal excitability and conditional escape behavior.
"Afterwards, when we used optogenetics to inhibit the activity of PV neurons in limbic TRN, the escape behavior of the mice disappeared, and the freezing behavior occurred. When the neurons were activated, the mice developed defensive evasion. Jumping and other behaviors. This indicates that PV neurons in limbic TRN play an important role in defensive evasion," explains Wang Hao, the first author of the paper and a doctoral student at Zhejiang University School of Medicine.
So, what is the neural loop mechanism of PV neurons in the limbic TRN to regulate fear-avoidance behavior? Next, the research team used the method of cis and reverse virus tracking to find the upstream (front ligament cortex, Cg) and downstream (thalary nucleus, IMD) of this group of neurons. By activating Cg to the limbic TRN loop, it is possible to inhibit the activity of downstream IMD neurons and reduce the excitatory input to the amygdala, thereby promoting defensive escape behavior.
Provide important clues for the pathogenesis of PTSD
The reviewer of Nature-Neuroscience evaluated the study as “highly original and unexpected.†It pointed out that the study “is not only original, but also a conceptual breakthrough, which is important for understanding defensive escape behavior. Contributing, and "opening up new areas of fear research, providing new research ideas and directions for further research on how animals make decisions when faced with a fearful environment."
Wang Liming, a professor at the Institute of Life Sciences at Zhejiang University, commented that the interesting thing about the study is that the research data suggests how the two fear behavioral responses—escape and freeze (installation)—are coordinated. He explained: "The researchers found that the activity of IMD neurons does not actually output escape behavior; on the contrary, it outputs deadly behavior. That is, the newly discovered cortical thalamus loop is passed. Inhibiting the activity of IMD neurons—that is, the output of lethal behavior—to achieve the output of escape behavior. This provides a new theoretical fulcrum for us to understand the behavioral choices of animals in the face of danger.â€
With this new pivot, scientists can continue to ask questions later. "We can immediately ask a series of important new questions: Can you think that this reaction is a default behavioral output, and only in certain situations, will IMD neurons start to escape? IMD neurons The level of activity, can it directly determine the behavioral decision to escape or pretend to be dead? If so, how is the activity of this decision-making center adjusted? In addition to this newly discovered loop, where will it receive the danger? Information? When receiving sensory information from the cortex, how does it judge the urgency of the danger? In the process, will the past experience and emotional state participate in it, and how is it involved?" Ming said an example. He also stressed that the significance of a good study is here: "To what extent does it give us the opportunity to ask more new and important issues, and to what extent it provides a fulcrum to solve these problems."
In addition, after experiencing serious natural disasters, cruel warfare experiences, violent attacks, and sexual assaults, some people may suffer from post-traumatic stress disorder without timely psychological counseling and treatment. It mainly includes active avoidance and numbness symptoms, or increased alertness, shock-stimulation, and even behaviors such as addiction, depression, and suicide, which may affect the recall of traumatic events. Mental health, interpersonal, learning, and work. This new study also provides important clues to the pathogenesis of PTSD.
This is the third paper on the emotional neural circuit research reported by Li Xiaoming's team in 2019. In January of this year, the team's research findings on the discovery of aversion to the depression and the involvement of the loop in the addiction were published in Nature-Medical and Neuron. For the future research direction, Li Xiaoming introduced to the Journal of Chinese Academy of Sciences: "Based on further exploration and clarification of the neural circuit mechanism of emotional and psychiatric diseases, we will focus on the application of these original findings in the diagnosis and treatment of clinical psychiatric diseases. The possibility." They have recently conducted clinical research on some of the findings found above.
Source: Chinese Journal of Science
Silicone Gel Applicator MDK-SGA-01
China Silicone Dressing Wound,Precision Silicone Applicator,Dual Silicone Applicator,Silicone Based Dressing, we offered that you can trust. Welcome to do business with us.
Silicone Dressing Wound,Precision Silicone Applicator,Dual Silicone Applicator,Silicone Based Dressing
Henan Maidingkang Medical Technology Co.,Ltd , https://www.mdkmedicales.com