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How dopamine drives brain activity
A specialized MRI sensor reveals the neurotransmitter's influence on neural activity throughout the brain.
Using a specialized magnetic resonance imaging (MRI) sensor, MIT neuroscientists have discovered how dopamine released deep within the brain influences both nearby and distant brain regions.
Dopamine plays many roles in the brain, most notably related to movement, motivation, and reinforcement of behavior. However, until now it has been difficult to study precisely how a flood of dopamine affects neural activity throughout the brain. Using their new technique, the MIT team found that dopamine appears to exert significant effects in two regions of the brain's cortex, including the motor cortex.
"There has been a lot of work on the immediate cellular consequences of dopamine release, but here what we're looking at are the consequences of what dopamine is doing on a more brain-wide level," says Alan Jasanoff, an MIT professor of biological engineering, brain and cognitive sciences, and nuclear science and engineering. Jasanoff is also an associate member of MIT's McGovern Institute for Brain Research and the senior author of the study.
The MIT team found that in addition to the motor cortex, the remote brain area most affected by dopamine is the insular cortex. This region is critical for many cognitive functions related to perception of the body's internal states, including physical and emotional states.
MIT postdoc Nan Li is the lead author of the study, which appears today in Nature.
Like other neurotransmitters, dopamine helps neurons to communicate with each other over short distances. Dopamine holds particular interest for neuroscientists because of its role in motivation, addiction, and several neurodegenerative disorders, including Parkinson's disease. Most of the brain's dopamine is produced in the midbrain by neurons that connect to the striatum, where the dopamine is released.
For many years, Jasanoff's lab has been developing tools to study how molecular phenomena such as neurotransmitter release affect brain-wide functions. At the molecular scale, existing techniques can reveal how dopamine affects individual cells, and at the scale of the entire brain, functional magnetic resonance imaging (fMRI) can reveal how active a particular brain region is. However, it has been difficult for neuroscientists to determine how single-cell activity and brain-wide function are linked.
"There have been very few brain-wide studies of dopaminergic function or really any neurochemical function, in large part because the tools aren't there," Jasanoff says. "We're trying to fill in the gaps."
About 10 years ago, his lab developed MRI sensors that consist of magnetic proteins that can bind to dopamine. When this binding occurs, the sensors' magnetic interactions with surrounding tissue weaken, dimming the tissue's MRI signal. This allows researchers to continuously monitor dopamine levels in a specific part of the brain.
In their new study, Li and Jasanoff set out to analyze how dopamine released in the striatum of rats influences neural function both locally and in other brain regions. First, they injected their dopamine sensors into the striatum, which is located deep within the brain and plays an important role in controlling movement. Then they electrically stimulated a part of the brain called the lateral hypothalamus, which is a common experimental technique for rewarding behavior and inducing the brain to produce dopamine.
Then, the researchers used their dopamine sensor to measure dopamine levels throughout the striatum. They also performed traditional fMRI to measure neural activity in each part of the striatum. To their surprise, they found that high dopamine concentrations did not make neurons more active. However, higher dopamine levels did make the neurons remain active for a longer period of time.
"When dopamine was released, there was a longer duration of activity, suggesting a longer response to the reward," Jasanoff says. "That may have something to do with how dopamine promotes learning, which is one of its key functions."
After analyzing dopamine release in the striatum, the researchers set out to determine this dopamine might affect more distant locations in the brain. To do that, they performed traditional fMRI imaging on the brain while also mapping dopamine release in the striatum. "By combining these techniques we could probe these phenomena in a way that hasn't been done before," Jasanoff says.
The regions that showed the biggest surges in activity in response to dopamine were the motor cortex and the insular cortex. If confirmed in additional studies, the findings could help researchers understand the effects of dopamine in the human brain, including its roles in addiction and learning.
"Our results could lead to biomarkers that could be seen in fMRI data, and these correlates of dopaminergic function could be useful for analyzing animal and human fMRI," Jasanoff says.
The research was funded by the National Institutes of Health and a Stanley Fahn Research Fellowship from the Parkinson's Disease Foundation. Reprinted with permission of MIT News. Read the original article.
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Construction of the $500 billion dollar tech city-state of the future is moving ahead.
- The futuristic megacity Neom is being built in Saudi Arabia.
- The city will be fully automated, leading in health, education and quality of life.
- It will feature an artificial moon, cloud seeding, robotic gladiators and flying taxis.
The Red Sea area where Neom will be built:
Saudi Arabia Plans Futuristic City, "Neom" (Full Promotional Video)<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="c646d528d230c1bf66c75422bc4ccf6f"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/N53DzL3_BHA?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span>
Chronic irregular sleep in children was associated with psychotic experiences in adolescence, according to a recent study out of the University of Birmingham's School of Psychology.
A time for sleep<div class="rm-shortcode" data-media_id="Mt29uUqI" data-player_id="FvQKszTI" data-rm-shortcode-id="931343dee3c02121445e51e94ba22446"> <div id="botr_Mt29uUqI_FvQKszTI_div" class="jwplayer-media" data-jwplayer-video-src="https://content.jwplatform.com/players/Mt29uUqI-FvQKszTI.js"> <img src="https://cdn.jwplayer.com/thumbs/Mt29uUqI-1920.jpg" class="jwplayer-media-preview" /> </div> <script src="https://content.jwplatform.com/players/Mt29uUqI-FvQKszTI.js"></script> </div> <p>Previous studies had already suggested a link between persistent nightmares in childhood and psychosis and borderline personality disorder (BPD) by adolescence, but researchers at the University of Birmingham's School of Psychology wanted to see if a similar connection existed between these mental disorders and other childhood behavioral sleep problems.</p><p>To do this, they scoured data from the Avon Longitudinal Study of Parents and Children, a longitudinal cohort study that followed approximately 14,000 children born in Avon, England, in the early 1990s. The study followed the children for more than 13 years. During that time, mothers filled out questionnaires asking about the children's lives. Factors looked at included housing, parenting, nutrition, physical health, mental wellbeing, environmental exposures, and so on. </p><p>The cohort study inquired about sleep routines, sleep duration, and awakening frequency when the children were 6, 18, and 30 months old, and then again at 3.5, 4.8, and 5.8 years. It also assessed mental health in adolescence using semi-structured interviews, such as the Psychosis-Like Symptom Interview.</p><p>"We know that adolescence is a key developmental period to study the onset of many mental disorders, including psychosis or BPD. This is because of particular brain and hormonal changes which occur at this stage," <a href="https://www.birmingham.ac.uk/staff/profiles/psychology/marwaha-steven.aspx" target="_blank">Steven Marwaha</a>, professor of psychiatry at Birmingham and senior author on the study, <a href="https://www.sciencedaily.com/releases/2020/07/200701125431.htm" target="_blank">said in a release</a>. "Sleep may be one of the most important underlying factors—and it's one that we can influence with effective, early interventions, so it's important that we understand these links."</p><p>After compiling the data, the researchers discovered an association between children with irregular sleeping patterns and teenagers with <a href="https://www.mind.org.uk/information-support/types-of-mental-health-problems/psychosis/about-psychosis/" target="_blank">psychotic experiences</a>—that is, episodes when the person perceives reality differently than those around them. Even when depression at 10 years old was considered as a mediating factor, their findings still suggested "a specific pathway between these childhood sleep problems and adolescent psychotic experiences." </p><p>Toddlers with shorter nighttime sleep duration and late bedtimes were likewise associated with a <a href="https://www.nimh.nih.gov/health/topics/borderline-personality-disorder/index.shtml" target="_blank">borderline personality disorder</a>—a disorder marked by a pattern of varying moods, self-images, and behaviors—in their teenage years. Depression at age 10 did not mediate this particular association, suggesting a separate and more specific pathway. </p>
A more restful tomorrow<p>While the sample size was large and mental health was assessed with a validated interview, there nevertheless remain limitations to this data. For starters, sleep habits were based on mothers' reports. Because they came from memory, versus a more direct observation method such as actigraphy, these data may be prone to imperfect recollection and reporting error. There are also many confounders that could be secretly nudging the results, such as family conditions, prenatal medicines, and a host of environmental factors. Finally, <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6024884/#:~:text=Sleep%20difficulties%20in%20youth%20with,fear%20of%20dark%20%5B13%5D." target="_blank">the relationship between sleep problems and mental disorders</a> is both complex and two-way.</p><p>As such, the study shows an association between poor childhood sleep later mental disorders but does not prove a causal link. Parents need not worry that a string of nightmares or the eternal struggle settle into bed will be the first ingredients in a witches' brew of debilitating mental disorders. The goal of the study, the researchers point out, is not to create undue worry but improve our ability to recognize the signs of at-risk children and deliver necessary interventions earlier.</p><p>"The results of this study could have important implications for helping practitioners identify children who might be at higher risk for psychotic experiences or BPD symptoms in adolescence, and potentially lead to the design of more effectively targeted sleep or psychological interventions to prevent the onset or attenuate these mental disorders," Isabel Morales-Muñoz, the study's lead researcher, <a href="https://www.healio.com/news/psychiatry/20200702/childhood-sleep-problems-linked-to-adolescent-psychosis-borderline-personality-disorder#:~:text=Sleep%20problems%20during%20early%20childhood,study%20published%20in%20JAMA%20Psychiatry." target="_blank">told Healio Psychiatry</a><u>.</u></p><p>If a parent reading this is worried that their child's sleep patterns are deleterious, the take away should not be despair over an unyielding fate. It should be to seek professional help as soon as possible to begin improving sleep duration and quality. Even if you aren't worried, it's worth remembering that childhood experiences lay the foundation for a lifetime of salubrious sleeping habits. It's so much more than beauty rest.</p>
Are we genetically inclined for superstition or just fearful of the truth?
- From secret societies to faked moon landings, one thing that humanity seems to have an endless supply of is conspiracy theories. In this compilation, physicist Michio Kaku, science communicator Bill Nye, psychologist Sarah Rose Cavanagh, skeptic Michael Shermer, and actor and playwright John Cameron Mitchell consider the nature of truth and why some groups believe the things they do.
- "I think there's a gene for superstition, a gene for hearsay, a gene for magic, a gene for magical thinking," argues Kaku. The theoretical physicist says that science goes against "natural thinking," and that the superstition gene persists because, one out of ten times, it actually worked and saved us.
- Other theories shared include the idea of cognitive dissonance, the dangerous power of fear to inhibit critical thinking, and Hollywood's romanticization of conspiracies. Because conspiracy theories are so diverse and multifaceted, combating them has not been an easy task for science.