Scientists created confusion in mice to learn more about human psychology

Expansion / A study from the Washington University School of Medicine in St. Louis found that a computer game that stimulates mice to experience delusions could be important for understanding the neurobiological roots of psychology.

J. Kuhal

People suffering from psychological episodes often experience both visual and auditory hallucinations due to both neurochemical dopamine; Antipsychotics block dopamine receptors in the brain. But little is known about how the brain circuit changes at elevated dopamine levels. The humble mouse may be able to assist. An increase in dopamine in the brain can cause hearing loss in mice Recent paper Published in Science Journal An amazing link between how the human and the mouse brain is malfunctioning.

The idea of ​​confusing rats may sound ridiculous, but Adam Capes, a co-author of the Washington University School of Medicine in St. Louis, emphasized that this is not a joke and that mouse studies can shed light on human psychology. “It’s so easy to accept the argument that psychosis is a fundamentally human thing and say, ‘forget about mice’,” He said. “But right now, the identification of psychiatric patients has not improved significantly over the past decades, and that’s because we don’t really understand the neurobiology of the disease.”

Kepek’s lab is largely focused on developing a complete understanding of faith by studying their neuropsychiatry in mice, with the long-term goal of shedding light on self-reported beliefs in humans. Lead author Katharina Smack is a psychiatrist at the Cold Spring Harbor Laboratory in New York who studies psychosis and schizophrenia. They saw the opportunity to study interdisciplinary psychological disorders in animals.

Kepeks initially received considerable skepticism from colleagues, although animal models have given impetus to almost all major pioneers in biomedical science, especially mice. So why not use mice in neuroscience? Some people may argue that humans and mice are quite different to learn something useful about something as advanced as illusion. And even if rats are misleading, they have no means of conveying that experience to human users.

“I think it’s just an intuition that it doesn’t work – that [a mouse] “We don’t feel like it,” Capex told Aras. Until recently we could not study the brain, even in the mouse, for the realities we could. But neuroscience has made incredible progress in the last decade. We know that areas of the brain are unique to us. There is no evidence that these are areas that are prone to psychosis. This includes many common areas. We will not make progress in the treatment of psychiatric diseases unless we make them better in animals. “

Of rats and males

Kepecs Et al. Set up a computer game that can be played by both mice and humans. They play different sounds, obscured by background noise, and ask subjects if they have heard or not. “Human speech is very difficult to understand in a noisy environment,” He said. “We balance our previous knowledge of human speech with what we hear in order to understand the spoken language. You can easily imagine that this system can be unbalanced, and all of a sudden you hear everything.”

Human subjects clicked a button when they heard a voice; Mice blow their noses into the harbor. By moving the slider to measure human subjects, they were asked to rate the value of the belief they felt about the identity of a real sound (vs. a fictional one). Kepecs Et al. Findings found that human subjects who reported using more confusing-sounding auditory sounds were also more likely to experience spontaneous moods, although no one had a psychological condition.

“The brain appears to have a neural circuit that balances preconceptions and evidence, and the higher the basal level of dopamine, the more dependent it is on your previous beliefs,” he said. Kepecs said. “We think confusion is when this neural circuit is unbalanced, and antipsychotics balance it. Our computer games probably engage in this circuit, so events like confusion reflect this circuit imbalance.”

That neural circuit falls within the potentially sensory stratum, which lies between the brain’s stem circuitry and the cortex – this is where dopamine is strongly expressed. Striatal dopamine strengthens learning and decision making. “That’s where a lot of the auditory and visual cortical areas project,” Kepecs said. So we should not be surprised that this is a major area associated with vanity.

Time for ketamine

The researchers evaluated the level of confidence in the rats to see how long the rats waited for the reward. They discovered that rats could be “primed” like the human subject, simply by changing how often the toy sounded in the toy with the hope of destruction. Most of the time the sound was played, the mice were more likely to “report” with confidence they had not heard any sound.

Next, the team implanted a small fiber optic sensor in mice to record dopamine levels in real time, and gave some mice ketamine, which can impair visual and sound perception. Mice receiving ketamine showed signs of many confusions. This is evidence for a similar brain circuit link between sensory striatum and more dopamine in hallucinations. Excess dopamine had made the brains of deceptive mice “wrong”. Capps thinks that people with hearing loss have brains that are similarly misinterpreted, although he has yet to prove them experimentally.

The hope is that this research sheds light on the underlying neural circuits responsible for confusion and may one day lead to improved treatment for psychosis in humans. “Despite the tremendous weakness of nature [psychotic] On condition, we haven’t seen any change in how we treat it in the long run, “Capex said.” In fact, pharmaceutical companies have had to give up, mainly because of a lasting understanding of neurobiology. We are very excited about this computational approach to studying the delusions of species that will eventually enable us to investigate the neurobiological roots of this mysterious experience. “

DOI: Science, 2021. 10.1126 / science.abf4740 (About DOI).

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