Posts Tagged ‘brain’

evolution-personality-neurosciencenews

How and why human-unique characteristics such as highly social behavior, languages and complex culture have evolved is a long-standing question. A research team led by Tohoku University in Japan has revealed the evolution of a gene related to such human-unique psychiatric traits.

PhD candidate Daiki Sato and Professor Masakado Kawata have discovered SLC18A1 (VMAT1), which encodes vesicular monoamine transporter 1, as one of the genes evolved through natural selection in the human lineage. VMAT1 is mainly involved in the transport of neurochemicals, such as serotonin and dopamine in the body, and its malfunction leads to various psychiatric disorders. VMAT1 has variants consisting of two different amino acids, threonine (136Thr) and isoleucine (136Ile), at site 136.

Several studies have shown that these variants are associated with psychiatric disorders, including schizophrenia, bipolar disorder, anxiety, and neuroticism (a personality trait). It has been known that individuals with 136Thr tend to be more anxious and more depressed and have higher neuroticism scores. They showed that other mammals have 136Asn at this site but 136Thr had been favored over 136Asn during human evolution. Moreover, the 136Ile variant had originated nearly at the Out-of-Africa migration, and then, both 136Thr and 136Ile variants have been positively maintained by natural selection in non-African populations.

The study by Sato and Kawata indicates that natural selection has possibly shaped our psychiatric traits and maintained its diversity. The results provide two important implications for human psychiatric evolution. First, through positive selection, the evolution from Asn to Thr at site 136 on SLC18A1 was favored by natural selection during the evolution from ancestral primates to humans, although individuals with 136Thr are more anxious and have more depressed minds.

Second, they showed that the two variants of 136Thr and 136Ile have been maintained by natural selection using several population genetic methods. Any form of natural selection that maintains genetic diversity within populations is called “balancing selection”. Individual differences in psychiatric traits can be observed in any human population, and some personality traits are also found in non-human primates. This suggests the possibility that a part of genetic diversity associated with personality traits and/or psychiatric disorders are maintained by balancing selection, although such selective pressure is often weak and difficult to detect.

https://neurosciencenews.com/personality-psychiatry-genetics-9820/

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zombie-neurons-identified-in-alzheimers-brains-309765
Senescent cells (represented here in green) no longer function but can broadcast inflammatory signals to the cells around them. These cells are implicated in a number of age-related diseases. Credit: The Mayo Clinic

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Darren Baker, Ph.D., a Mayo Clinic molecular biologist and senior author of the paper, and first author Tyler Bussian, a Mayo Clinic Graduate School of Biomedical Sciences student.

Zombie cells are the ones that can’t die but are equally unable to perform the functions of a normal cell. These zombie, or senescent, cells are implicated in a number of age-related diseases. And with a new letter in Nature, Mayo Clinic researchers have expanded that list.

In a mouse model of brain disease, scientists report that senescent cells accumulate in certain brain cells prior to cognitive loss. By preventing the accumulation of these cells, they were able to diminish tau protein aggregation, neuronal death and memory loss.

“Senescent cells are known to accumulate with advancing natural age and at sites related to diseases of aging, including osteoarthritis; atherosclerosis; and neurodegenerative diseases, such as Alzheimer’s and Parkinson’s,” says Darren Baker, Ph.D., a Mayo Clinic molecular biologist and senior author of the paper. “In prior studies, we have found that elimination of senescent cells from naturally aged mice extends their healthy life span.”

In the current study, the team used a model that imitates aspects of Alzheimer’s disease.

“We used a mouse model that produces sticky, cobweb like tangles of tau protein in neurons and has genetic modifications to allow for senescent cell elimination,” explains first author Tyler Bussian, a Mayo Clinic Graduate School of Biomedical Sciences student who is part of Dr. Baker’s lab. “When senescent cells were removed, we found that the diseased animals retained the ability to form memories, eliminated signs of inflammation, did not develop neurofibrillary tangles, and had maintained normal brain mass.” They also report that pharmacological intervention to remove senescent cells modulated the clumping of tau proteins.

Also, the team was able to identify the specific type of cell that became senescent, says Dr. Baker.

“Two different brain cell types called ‘microglia’ and ‘astrocytes’ were found to be senescent when we looked at brain tissue under the microscope,” says Bussian. “These cells are important supporters of neuronal health and signaling, so it makes sense that senescence in either would negatively impact neuron health.”

The finding was somewhat surprising, explains Dr. Baker, because at the time their research started, a causal link between senescent cells and neurodegenerative disease had not been established.

“We had no idea whether senescent cells actively contributed to disease pathology in the brain, and to find that it’s the astrocytes and microglia that are prone to senescence is somewhat of a surprise, as well,” says Dr. Baker.

In terms of future work, Dr. Baker explains that this research lays out the best-case scenario, where prevention of damage to the brain avoided the disease state. “Clearly, this same approach cannot be applied clinically, so we are starting to treat animals after disease establishment and working on new models to examine the specific molecular alterations that occur in the affected cells,” says Dr. Baker.

In addition to Dr. Baker and Bussian, the other authors are Asef Aziz, a medical student formerly at Mayo Clinic; Charlton Meyer, Mayo Clinic; Barbara Swenson, Ph.D., Mayo Clinic; and Jan van Deursen, Ph.D., Mayo Clinic. Dr. van Deursen is the Vita Valley Professor of Cellular Senescence. Drs. Baker and van Deursen are inventors on patents licensed to Unity Biotechnology by Mayo Clinic, and Dr. van Deursen is a co-founder of Unity Biotechnology.

Funding for this research was provided by the Ellison Medical Foundation, the Glenn Foundation for Medical Research, the National Institutes of Health, the Mayo Clinic Children’s Research Center, and the Alzheimer’s Disease Research Center of Mayo Clinic.

https://newsnetwork.mayoclinic.org/discussion/senescent-cells-found-in-brains-of-mice-prior-to-cognitive-loss/

hippocampus
The hippocampus is a region of the brain largely responsible for memory formation.

Why can some people comfortably walk between skyscrapers on a high-wire or fearlessly raft Niagara Falls in a wooden barrel, whereas others freeze at the mere thought of climbing off escalators in a shopping mall? In a new study, scientists have found that a certain type of cell in the hippocampus plays a key role.

People differ when it comes to trying dangerous or exhilarating activities. Even siblings can show dramatic differences in risk-taking behaviour. The neural mechanisms that drive risk-taking behaviour are largely unknown. However, scientists from the Department of Neuroscience of Uppsala University in Sweden and the Brain Institute of the Federal University of Rio Grande do Norte in Brazil have found that some cells in the hippocampus play a key role in risk-taking behaviour and anxiety.

In an article published in the journal Nature Communications, the authors show that neurons known as OLM cells, when stimulated, produce a brain rhythm that is present when animals feel safe in a threatening environment (for example, when they are hiding from a predator but aware of the predator’s proximity). The study, produced by Drs. Sanja Mikulovic, Ernesto Restrepo, Klas Kullander and Richardson Leao, among others, showed that anxiety and risk-taking behaviour can be controlled by the manipulation of OLM cells. To find a pathway that quickly and robustly modulates risk-taking behaviour is very important for treatment of pathological anxiety, since reduced risk-taking behaviour is a trait in people with high anxiety levels.

Adaptive (or normal) anxiety is essential for survival because it protects us from harm. Unfortunately, in a large number of people, anxiety can be dysfunctional and severely interfere with daily life. In these cases, doctors often rely on antidepressants to help patients recover from the dysfunctional state. However, these drugs act in the entire brain and not only in the areas where it is needed, and may therefore cause severe side-effects. Thus, drugs that affect a single brain region or a very specific group of cells may be a major breakthrough in treating anxiety and associated disorders like depression. Another interesting finding in the study is that OLM cells can be controlled by pharmacological agents. In the past, the same group of scientists found that OLM cells were the gatekeepers of memories in the hippocampus, and that these cells were very sensitive to nicotine.

“This finding may explain why people binge-smoke when they are anxious,” says Dr. Richardson Leao, researcher at the Brain Institute of the Federal University of Rio Grande do Norte.

The participation of the hippocampus in emotions is much less studied than its role in memory and cognition. In 2014, for example, the Nobel prize was awarded for the discovery of “place cells” that represent a biological GPS and underlie the memories of where we are located in our surroundings. In the past decade, scientists have also started to appreciate the role of the hippocampus in regulating emotions.

“It is fascinating how different regions of the same brain structure control distinct behaviours and how they interact with each other. Identifying specific circuits that underlie either cognitive or emotional processes is crucial for the general understanding of brain function and for more specific drug development to treat disorders,” says Dr. Sanja Mikulovic, Uppsala University.

The discovery of these neurons and their role in anxiety and risk-taking may open a path for the development of highly efficient anxiolytics and antidepressants without common side-effects, such as apathy.

Sanja Mikulovic et al, Ventral hippocampal OLM cells control type 2 theta oscillations and response to predator odor, Nature Communications (2018). DOI: 10.1038/s41467-018-05907-w

https://medicalxpress.com/news/2018-09-bravery-associated-cells-hippocampus.html

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by DAVID NIELD

New research suggests the human eye and brain are capable of seeing ghosted images, a new type of visual phenomenon that scientists previously thought could only be detected by a computer. It turns out our eyes are more powerful than we thought.

The discovery could teach us more about the inner workings of the eye and brain and how they process information, as well as changing our thinking on what we human beings can truly see of the world around us.

Having been developed as a way of low-cost image capture for light outside the visible spectrum, the patterns produced by these ghosted images are usually processed by software algorithms – but, surprisingly, our eyes have the same capabilities.

“Ghost-imaging with the eye opens up a number of completely novel applications such as extending human vision into invisible wavelength regimes in real-time, bypassing intermediary screens or computational steps,” write the researchers.

“Perhaps even more interesting are the opportunities that ghost imaging offers for exploring neurological processes.”

Ghost imaging works using a camera with a single pixel, rather than the millions of pixels used by the sensors inside today’s digital cameras and smartphones. When it comes to capturing light beyond the visible spectrum, it’s even a more cost-effective method.

These single pixel cameras capture light as it reflects from an object – by watching different random patterns of bouncing light, and crunching through some calculations, the camera can gradually build up a picture of something even with just one pixel.

In some setups, the single pixel camera is used in combination with a second light, modulated in response to the first, and beamed back on the original random patterns. The advantage is that fewer patterns are needed to produce an image.

In this case a second camera using some smart algorithms can pick up the image without having looked at the object at all – just by looking at the patterns being cast and the light being produced from them.

That’s the ghosted image that was previously thought to only be visible to computers running specialist software. However, the new study shows the human visual perception can make sense of these patterns, called Hadamard patterns.

This diagram from the research paper should give you an idea of what’s happening:

ghosted-images-2

It’s a little bit like when our eyes and brains look at a series of still images and treat them as a moving picture – the same sort of subconscious processing seems to be going on.

Of the four volunteers who took part in the study, all four could make out an image of Albert Einstein sticking out his tongue from the Hadamard patterns. Interestingly, though, the illusion only appeared when the patterns were projected quickly enough.

If the rate dropped below 200 patterns per 20 milliseconds, the image couldn’t be seen by the study participants.

As the researchers point out, this is potentially hugely exciting – it means we might be able to devise simple systems to see light outside the visible spectrum, with no computer processing required in the middle.

That’s all to come – and this is really preliminary stuff, so we can’t get too carried away. For now, the team of researchers is using the findings to explore more about how our visual systems work, and whether our eyes and brains have yet-undiscovered superpowers for looking at the world around us.

The research has yet to be peer-reviewed, but you can read it on the pre-print resource Arxiv.

https://www.sciencealert.com/human-eye-sees-ghosted-images-reflected-light

Researchers led by Northwestern Engineering’s Luis Amaral sifted through data from more than 1.5 million questionnaire respondents to find at least four distinct clusters of personality types exist — average, reserved, self-centered, and role model — challenging existing paradigms in psychology.

“People have tried to classify personality types since Hippocrates’s time, but previous scientific literature has found that to be nonsense,”said co-author William Revelle, professor of psychology at Northwestern University’s Weinberg College of Arts and Sciences.

“Now, these data show there are higher densities of certain personality types,” said Revelle, who specializes in personality measurement, theory, and research.

The new study appears in Nature Human Behaviour. The findings potentially could be of interest to hiring managers and mental healthcare providers.

Initially, Revelle was skeptical of the study’s premise. The concept of personality types remains controversial in psychology, with hard scientific proof difficult to find. Previous attempts based on small research groups created results that often were not replicable.

“Personality types only existed in self-help literature and did not have a place in scientific journals,” said Amaral, Erastus Otis Haven Professor of Chemical and Biological Engineering at the McCormick School of Engineering. “Now, we think this will change because of this study.”

The new research combined an alternative computational approach with data from four questionnaires, attracting more than 1.5 million respondents from around the world. The questionnaires, developed by the research community over the decades, have between 44 and 300 questions. People voluntarily take the online quizzes, attracted by the opportunity to receive feedback about their own personality.

These data are now being made available to other researchers for independent analyses.

“A study with a dataset this large would not have been possible before the web,” Amaral said. “Previously, researchers would recruit undergrads on campus and maybe get a few hundred people. Now, we have all these online resources available, and data is being shared.”

Average

Average people are high in neuroticism and extraversion, while low in openness. “I would expect that the typical person would be in this cluster,” said Martin Gerlach, a postdoctoral fellow in Amaral’s lab and the paper’s first author. Females are more likely than males to fall into the Average type.

Reserved

The Reserved type is emotionally stable, but not open or neurotic. They are not particularly extraverted but are somewhat agreeable and conscientious.

Role Models

Role Models score low in neuroticism and high in all the other traits. The likelihood that someone is a role model increases dramatically with age. “These are people who are dependable and open to new ideas,” Amaral said. “These are good people to be in charge of things. In fact, life is easier if you have more dealings with role models.” More women than men are likely to be role models.

Self-Centered

Self-Centered people score very high in extraversion and below average in openness, agreeableness and conscientiousness. “These are people you don’t want to hang out with,” Revelle said. There is a very dramatic decrease in the number of self-centered types as people age, both with women and men.

The group’s first attempt to sort the data used traditional clustering algorithms, but that yielded inaccurate results, Amaral said.

“At first, they came to me with 16 personality types, and there’s enough literature that I’m aware of that says that’s ridiculous,” Revelle said. “I believed there were no types at all.”

He challenged Amaral and Gerlach to refine their data.

“Machine learning and data science are promising but can be seen as a little bit of a religion,” Amaral said. “You still need to test your results. We developed a new method to guide people to solve the clustering problem to test the findings.”

Their algorithm first searched for many clusters using traditional clustering methods, but then winnowed them down by imposing additional constraints. This procedure revealed the four groups they reported.

“The data came back, and they kept coming up with the same four clusters of higher density and at higher densities than you’d expect by chance, and you can show by replication that this is statistically unlikely,” Revelle said.

“I like data, and I believe these results,” he added. “The methodology is the main part of the paper’s contribution to science.”

To be sure the new clusters of types were accurate, the researchers used a notoriously self-centered group—teenaged boys—to validate their information.

“We know teen boys behave in self-centered ways,” Amaral said. “If the data were correct and sifted for demographics, they would they turn out to be the biggest cluster of people.”

Indeed, young males are overrepresented in the Self-Centered group, while females over 15 years old are vastly underrepresented.

Along with serving as a tool that can help mental health service providers assess for personality types with extreme traits, Amaral said the study’s results could be helpful for hiring managers looking to insure a potential candidate is a good fit or for people who are dating and looking for an appropriate partner.

And good news for parents of teenagers everywhere: As people mature, their personality types often shift. For instance, older people tend to be less neurotic yet more conscientious and agreeable than those under 20 years old.

“When we look at large groups of people, it’s clear there are trends, that some people may be changing some of these characteristics over time,” Amaral said. “This could be a subject of future research.”

This article has been republished from materials provided by Northwestern University. Note: material may have been edited for length and content. For further information, please contact the cited source.

Reference:

Martin Gerlach, Beatrice Farb, William Revelle, Luís A. Nunes Amaral. A robust data-driven approach identifies four personality types across four large data sets. Nature Human Behaviour, 2018; DOI: 10.1038/s41562-018-0419-z

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Greater deactivation of the posterior cingulate cortex, a brain region associated with processing self-related thoughts, was associated with lower pain and higher trait mindfulness. Credit: Wake Forest Baptist Medical Center

Ever wonder why some people seem to feel less pain than others? A study conducted at Wake Forest School of Medicine may have found one of the answers—mindfulness. “Mindfulness is related to being aware of the present moment without too much emotional reaction or judgment,” said the study’s lead author, Fadel Zeidan, Ph.D., assistant professor of neurobiology and anatomy at the medical school, part of Wake Forest Baptist Medical Center. “We now know that some people are more mindful than others, and those people seemingly feel less pain.”

The study is an article in press, published ahead-of-print in the journal Pain.

The researchers analyzed data obtained from a study published in 2015 that compared mindfulness meditation to placebo analgesia. In this follow-up study, Zeidan sought to determine if dispositional mindfulness, an individual’s innate or natural level of mindfulness, was associated with lower pain sensitivity, and to identify what brain mechanisms were involved.

In the study, 76 healthy volunteers who had never meditated first completed the Freiburg Mindfulness Inventory, a reliable clinical measurement of mindfulness, to determine their baseline levels. Then, while undergoing functional magnetic resonance imaging, they were administered painful heat stimulation (120°F).

Whole brain analyses revealed that higher dispositional mindfulness during painful heat was associated with greater deactivation of a brain region called the posterior cingulate cortex, a central neural node of the default mode network. Further, in those that reported higher pain, there was greater activation of this critically important brain region.

The default mode network extends from the posterior cingulate cortex to the medial prefrontal cortex of the brain. These two brain regions continuously feed information back and forth. This network is associated with processing feelings of self and mind wandering, Zeidan said.

“As soon as you start performing a task, the connection between these two brain regions in the default mode network disengages and the brain allocates information and processes to other neural areas,” he said.

“Default mode deactivates whenever you are performing any kind of task, such as reading or writing. Default mode network is reactivated whenever the individual stops performing a task and reverts to self-related thoughts, feelings and emotions. The results from our study showed that mindful individuals are seemingly less caught up in the experience of pain, which was associated with lower pain reports.”

The study provided novel neurobiological information that showed people with higher mindfulness ratings had less activation in the central nodes (posterior cingulate cortex) of the default network and experienced less pain. Those with lower mindfulness ratings had greater activation of this part of the brain and also felt more pain, Zeidan said.

“Now we have some new ammunition to target this brain region in the development of effective pain therapies. Importantly this work shows that we should consider one’s level of mindfulness when calculating why and how one feels less or more pain,” Zeidan said. “Based on our earlier research, we know we can increase mindfulness through relatively short periods of mindfulness meditation training, so this may prove to be an effective way to provide pain relief for the millions of people suffering from chronic pain.”

https://medicalxpress.com/news/2018-09-mindful-people-pain-mri-imaging.html

largest-ever-study-of-genetic-links-to-depression-and-anxiety-launched-309700

The NIHR and King’s College London are calling for 40,000 people diagnosed with depression or anxiety to enrol online for the Genetic Links to Anxiety and Depression (GLAD) Study and join the NIHR Mental Health Bioresource.

Researchers hope to establish the largest ever database of volunteers who can be called up to take part in research exploring the genetic factors behind the two most common mental health conditions – anxiety and depression.

[youtube=https://youtu.be/wzgvS8gU2Ss\

The GLAD study will make important strides towards better understanding of these disorders and provide a pool of potential participants for future studies, reducing the time-consuming process of recruiting patients for research.

Research has shown 30-40% of the risk for both depression and anxiety is genetic and 60-70% due to environmental factors. Only by having a large, diverse group of people available for studies will researchers be able to determine how genetic and environmental triggers interact to cause anxiety and depression.

Leader of the GLAD study and the NIHR Mental Health BioResource, Dr Gerome Breen of King’s College London, said: “It’s a really exciting time to become involved in mental health research, particularly genetic research which has made incredible strides in recent years – we have so far identified 46 genetic links for depression and anxiety.

“By recruiting 40,000 volunteers willing to be re-contacted for research, the GLAD Study will take us further than ever before. It will allow researchers to solve the big unanswered questions, address how genes and environment act together and help develop new treatment options.”

The GLAD Study, a collaboration between the NIHR BioResource and King’s College London, has been designed to be particularly accessible, with a view to motivating more people to take part in mental health research.

Research psychologist and study lead Professor Thalia Eley, King’s College London, said: “We want to hear from all different backgrounds, cultures, ethnic groups and genders, and we are especially keen to hear from young adults. By including people from all parts of the population, what we learn will be relevant to everyone. This is a unique opportunity to participate in pioneering medical science.”

https://www.nihr.ac.uk/news/nihr-launches-largest-ever-study-of-genetic-links-to-depression-and-anxiety/9201