Posts tagged science
Articles and news from the latest research reports.
More left-handed men are born during the winter
Men born in November, December or January are more likely of being left-handed than during the rest of the year. While the genetic bases of handedness are still under debate, scientists at the Faculty of Psychology, University of Vienna, obtained indirect evidence of a hormonal mechanism promoting left-handedness among men. Psychologist Ulrich Tran and his colleagues published their findings in the scientific journal “Cortex”.
Various manual tasks in everyday life require the use of the right hand or are optimized for right-handers. Around 90 percent of the general population is right-handed, only about 10 percent is left-handed. The study of Ulrich Tran, Stefan Stieger, and Martin Voracek comprised two large and independent samples of nearly 13000 adults from Austria and Germany. As in modern genetic studies, where a discovery-and-replication-sample design is standard, the use of two samples allowed testing the replicability and robustness of findings within one-and-the-same study. Overall, 7.5 percent of women and 8.8 percent of men were left-handed. “We were surprised to see that this imbalance was caused by more left-handed men being born specifically during November, December, and January. On a monthly average, 8.2 percent of left-handed men were born during the period February to October. During November to January, this number rose to 10.5 percent”, according to Ulrich Tran, lead author of the study.
A hormonal cause during embryonic development
"Presumably, the relative darkness during the period November to January is not directly connected to this birth seasonality of handedness. We assume that the relative brightness during the period May to July, half a year before, is its distal cause", explains Ulrich Tran. A theory, brought forth in the 1980s by US neurologists Norman Geschwind and Albert Galaburda, posits that testosterone delays the maturation of the left brain hemisphere during embryonic development. The left brain hemisphere is dominant among right-handers, the right brain hemisphere is dominant among left-handers. Intrauterine testosterone levels are higher in the male fetus, because of its own testosterone secretion, than in the female fetus. However, the testosterone level of the mother and external factors may also affect intrauterine testosterone levels. Specifically, more daylight may increase testosterone levels, making a seasonality effect plausible.
Previous studies on the subject provided mixed and inconsistent evidence. There was no clear indication which season has an effect, and whether seasonality affects men, women or both sexes equally. According to the current findings, there is a small, but robust and replicable, effect of birth seasonality on handedness, affecting only men. These results are consistent with a hormonal basis of handedness, corroborating thus an old and controversial theory. However, the exact way of causation needs to be investigated in future studies.
(Source: medienportal.univie.ac.at)
Tool helps guide brain cancer surgery
A tool to help brain surgeons test and more precisely remove cancerous tissue was successfully used during surgery, according to a Purdue University and Brigham and Women’s Hospital study.
The Purdue-designed tool sprays a microscopic stream of charged solvent onto the tissue surface to gather information about its molecular makeup and produces a color-coded image that reveals the location, nature and concentration of tumor cells.
”In a matter of seconds this technique offers molecular information that can detect residual tumor that otherwise may have been left behind in the patient,” said R. Graham Cooks, the Purdue professor who co-led the research team. “The instrumentation is relatively small and inexpensive and could easily be installed in operating rooms to aid neurosurgeons. This study shows the tremendous potential it has to enhance patient care.”
Current surgical methods rely on the surgeon’s trained eye with the help of an operating microscope and imaging from scans performed before surgery, Cooks said.
"Brain tumor tissue looks very similar to healthy brain tissue, and it is very difficult to determine where the tumor ends and the normal tissue begins," he said. "In the brain, millimeters of tissue can mean the difference between normal and impaired function. Molecular information beyond what a surgeon can see can help them precisely and comprehensively remove the cancer."
The mass spectrometry-based tool had previously been shown to accurately identify the cancer type, grade and tumor margins of specimens removed during surgery based on an evaluation of the distribution and amounts of fatty substances called lipids within the tissue. This study took the analysis a step further by additionally evaluating a molecule associated with cell growth and differentiation that is considered a biomarker for certain types of brain cancer, he said.
"We were able to identify a single metabolite biomarker that provides information about tumor classification, genotype and the prognosis for the patient," said Cooks, the Henry Bohn Hass Distinguished Professor of Chemistry. "Through mass spectrometry all of this information can be obtained from a biopsy in a matter of minutes and without significantly interrupting the surgical procedure."
For this study, which included validation on samples and use during two patients’ surgical procedures, the tool was tuned to identify the lipid metabolite 2-hydroxyglutarate or 2-HG. This biomarker is associated with more than 70 percent of gliomas and can be used to classify the tumors, he said.
A paper detailing the results of the National Institutes of Health-funded study will be published in an upcoming issue of the Proceedings of the National Academy of Sciences and is published online.
In mass spectrometry molecules are electrically charged and turned into ions so that they can be identified by their mass. The new tool relies an ambient mass spectrometry analysis technique developed by Cooks and his colleagues called desorption electrospray ionization, or DESI, which eliminated the need for chemical manipulations of samples and containment in a vacuum chamber for ionization. DESI allows ionization to occur directly on surfaces outside of the mass spectrometers, making the process much simpler, faster and more applicable to surgical settings.
The tool couples a DESI mass spectrometer with a software program designed by the research team that uses the results to characterize the brain tumors and detect boundaries between healthy and cancerous tissue. The program is based on earlier studies of lipid patterns that correspond to different types and grades of cancer and currently covers the two most common types of brain tumors, gliomas and meningiomas. These two types of tumors combined account for about 65 percent of all brain tumors and 80 percent of all malignant brain tumors, according to the American Brain Tumor Association.
Additional classification methodologies and metabolite biomarkers could be added to tailor the tool to different types of cancer, Cooks said.
The brain surgery was performed in the Advanced Multi-Modality Image Guided Operating suite, or AMIGO at Brigham and Women’s Hospital.
Dr. Nathalie Agar, director of the Surgical Molecular Imaging Laboratory within the neurosurgery department at Brigham and Women’s Hospital, led the study.
Researchers discover a “switch” in Alzheimer’s and stroke patient brains
A new study by researchers at Sanford-Burnham Medical Research Institute (Sanford-Burnham) has identified a chemical “switch” that controls both the generation of new neurons from neural stem cells and the survival of existing nerve cells in the brain. The switch that shuts off the signals that promote neuron production and survival is in abundance in the brains of Alzheimer’s patients and stroke victims. The study, published July 3 in Cell Reports, suggests that chemical switch, MEF2, may be a potential therapeutic target to protect against neuronal loss in a variety of neurodegenerative diseases, such as Alzheimer’s, Parkinson’s and autism.
“We have shown that when nitric oxide (NO)—a highly reactive free radical—reacts with MEF2, MEF2 can no longer bind to and activate the genes that drive neurogenesis and neuronal survival,” said Stuart Lipton, M.D., Ph.D., director and professor in the Neuroscience and Aging Research Center at Sanford-Burnham, and a practicing clinical neurologist. “What’s unique here is that a single alteration to MEF2 controls two distinct events—the generation of new neurons and the survival of existing neurons,” added Lipton, who is senior author of the study.
In the brain, transcription factors are critical for linking external stimuli to protein production, enabling neurons to adapt to changing environments. Members of the MEF2 family of transcription factors have been shown to play an important role in neurogenesis and neuronal survival, as well as in the processes of learning and memory. And, mutations of the MEF2 gene have been associated with a range of neurodegenerative disorders, including Alzheimer’s and autism.
The process of NO-protein modifications—known as S-nitrosylation—was first described by Lipton and collaborators some 20 years ago. S-nitrosylation has important regulatory functions under normal physiological conditions throughout the body. However, with aging, environmental toxins, or stress-related injuries, abnormal S-nitrosylation reactions can occur, contributing to disease pathogenesis.
“Our laboratory had previously shown that S-nitrosylation of MEF2 controlled neuronal survival in Parkinson’s disease,” said Lipton. “Now we have shown that this same reaction is more ubiquitous, occurring in other neurological conditions such as stroke and Alzheimer’s disease. While the major gene targets of MEF2 may be different in various diseases and brain areas, the remarkable new finding here is that we may be able to treat each of these neurological disorders by preventing a common S-nitrosylation modification to MEF2.
“The findings suggest that the development of a small therapeutic molecule—one that can cross the blood-brain barrier and block S-nitrosylation of MEF2 or in some other way increase MEF2 transcriptional activity—could promote new brain cell growth and protect existing cells in several neurodegenerative disorders,” added Lipton.
“We have already found several such molecules in our high-throughput screening and drug discovery efforts, so the potential for developing new drugs to attack this pathway is very exciting,” said Lipton.
Schizophrenia-Associated Gene Variation Affects Brain Cell Development
Johns Hopkins researchers have begun to connect the dots between a schizophrenia-linked genetic variation and its effect on the developing brain. As they report July 3 in the journal Cell Stem Cell, their experiments show that the loss of a particular gene alters the skeletons of developing brain cells, which in turn disrupts the orderly layers those cells would normally form.
(Image caption: Left, human neural stem cells form rosettes as they grow into different cell types, with ringlike patterns of PKCλ protein in the center. A neural rosette with a 15q11.2 microdeletion, a risk factor for schizophrenia, appears disorganized and lacks the ringlike PKCλ protein structure, right, suggesting that this risk factor acts early in the neurodevelopmental process. Credit: Ki-Jun Yoon/Johns Hopkins Medicine)
“This is an important step toward understanding what physically happens in the developing brain that puts people at risk of schizophrenia,” says Guo-li Ming, M.D., Ph.D., a professor of neurology and neuroscience in the Johns Hopkins University School of Medicine’s Institute for Cell Engineering.
While no single genetic mutation is known to cause schizophrenia, so-called genome wide association studies have identified variations that are more common in people with the condition than in the general population. One of these is a missing piece from an area of the genome labeled 15q11.2. “While the deletion is linked to schizophrenia, having extra copies of this part of the genome raises the risk of autism,” notes Ming.
For the new study, Ming’s research group, along with that of her husband and collaborator, neurology and neuroscience professor Hongjun Song, Ph.D., used skin cells from people with schizophrenia who were missing part of 15q11.2 on one of their chromosomes. (Because everyone carries two copies of their genome, the patients each had an intact copy of 15q11.2 as well.)
The researchers grew the human skin cells in a dish and coaxed them to become induced pluripotent stem cells, and then to form neural progenitor cells, a kind of stem cell found in the developing brain.
“Normally, neural progenitors will form orderly rings when grown in a dish, but those with the deletion didn’t,” Ming says. To find out which of the four known genes in the missing piece of the genome were responsible for the change, the researchers engineered groups of progenitors that each produced less protein than normal from one of the suspect genes. The crucial ingredient in ring formation turned out to be a gene called CYFIP1.
The team then altered the genomes of neural progenitors in mouse embryos so that they made less of the protein created by CYFIP1. The brain cells of the fetal mice turned out to have similar defects in structure to those in the dish-grown human cells. The reason, the team found, is that CYFIP1 plays a role in building the skeleton that gives shape to each cell, and its loss affects spots called adherens junctions where the skeletons of two neighboring cells connect.
Having less CYFIP1 protein also caused some neurons in the developing mice to end up in the wrong layer within the brain. “During development, new neurons get in place by ‘climbing’ the tendrils of neural progenitor cells,” Ming says. “We think that disrupted adherens junctions don’t provide a stable enough anchor for neural progenitors, so the ‘rope’ they form doesn’t quite get new neurons to the right place.”
The researchers say they also found that CYFIP1 is part of a complex of proteins called WAVE, which is key to building the cellular skeleton.
Many people with a CYFIP1 deletion do not get schizophrenia, so the team suspected the condition was more likely to arise in people with a second defect in the WAVE complex.
Analyzing data from genomewide association studies, they found a variation in the WAVE complex signaling gene ACTR2/Arp2 that, combined with the CYFIP1 deletion, increased the risk of schizophrenia more than either genetic change by itself.
In adding to science’s understanding of schizophrenia, the study also shows how other mental illnesses might be similarly investigated, the researchers say. “Using induced pluripotent stem cells from people with schizophrenia allowed us to see how their genes affected brain development,” says Song. “Next, we’d like to investigate what effects remain in the mature brain.”
(Source: hopkinsmedicine.org)
Blind lead the way in brave new world of tactile technology
Imagine feeling a slimy jellyfish, a prickly cactus or map directions on your iPad mini Retina display, because that’s where tactile technology is headed. But you’ll need more than just an index finger to feel your way around.
New research at UC Berkeley has found that people are better and faster at navigating tactile technology when using both hands and several fingers. Moreover, blind people in the study outmaneuvered their sighted counterparts – especially when using both hands and several fingers – possibly because they’ve developed superior cognitive strategies for finding their way around.
Bottom line: Two hands are better than one in the brave new world of tactile or “haptic” technology, and the visually impaired can lead the way.
”Most sighted people will explore these types of displays with a single finger. But our research shows that this is a bad decision. No matter what the task, people perform better using multiple fingers and hands,” said Valerie Morash, a doctoral student in psychology at UC Berkeley, and lead author of the study just published in the online issue of the journal, Perception.
“We can learn from blind people how to effectively use multiple fingers, and then teach these strategies to sighted individuals who have recently lost vision or are using tactile displays in high-stakes applications like controlling surgical robots,” she added.
For decades, scientists have studied how receptors on the fingertips relay information to the brain. Now, researchers at Disney and other media companies are implementing more tactile interfaces, which use vibrations, and electrostatic or magnetic feedback for users to find their way around, or experience how something feels.
In this latest study, Morash and fellow researchers at UC Berkeley and the Smith-Kettlewell Eye Research Institute in San Francisco tested 14 blind adults and 14 blindfolded sighted adults on several tasks using a tactile map. Using various hand and finger combinations, they were tasked with such challenges as finding a landmark or figuring out if a road looped around.
Overall, both blind and sighted participants performed better when using both hands and several fingers, although blind participants were, on average, 50 percent faster at completing the tasks, and even faster when they used both hands and all their fingers.
“As we move forward with integrating tactile feedback into displays, these technologies absolutely need to support multiple fingers,” Morash said. “This will promote the best tactile performance in applications such as the remote control of robotics used in space and high-risk situations, among other things.”
(Source: newscenter.berkeley.edu)
Fruit fly research may reveal what happens in female brains during courtship and mating
What are the complex processes in the brain involved with choosing a mate, and are these processes different in females versus males? It’s difficult to study such questions in people, but researchers are finding clues in fruit flies that might be relevant to humans and other animals. Three different studies on the topic are being published in the Cell Press journals Neuron (1, 2) and Current Biology.
Work over the past 100 years has largely focused on the overt courtship behaviors that male flies direct toward females. However, the female ultimately decides whether to reject the male or copulate with him. How does the female make this decision? In one Neuron paper, researchers report that they have identified two small groups of neurons in the female brain that function to modulate whether she will mate or not with a male based on his distinct pheromones and courtship song. In this paper, a team led by Dr. Bruce Baker of the Howard Hughes Medical Institute’s Janelia Farm Research Campus in Virginia also reports that these neurons are genetically distinct from the previously identified neurons that function to drive the elaborate courtship ritual with which a male woos a female. “An understanding of the neural mechanisms underlying how sensory information elicits appropriate sexual behaviors can be used as a point of comparison for how similar sexual behavior circuits are structured and function in other species,” says Dr. Baker.
In the Current Biology study, Dr. Leslie Vosshall of The Rockefeller University in New York City and her team found that a small group of neurons in the abdominal nerve cord and reproductive tract—called Abdominal-B neurons—is necessary for the female to pause her movement and interact with a courting male. When the neurons are inactivated, the female ignores the male and keeps moving, but when the neurons are activated, the female spontaneously pauses. “Sexual courtship is a duet—the male and female send signals back and forth until they reach the point that copulation proceeds,” says Dr. Jennifer Bussell, the lead author of the study. “Pausing to interact with a male, rather than avoiding him, is a crucial step in any female’s behavior leading to copulation. Tying a group of neurons to this particular response to males will allow us to dissect in detail how female mating circuitry functions.”
In another Neuron paper, researchers studied the effects of a small protein called sex peptide that is transferred along with sperm from males to females and is detected by sensory neurons in the uterus. Sex peptide changes the female’s behavior so that she is reluctant to mate again for about10 days. The investigators traced the neuronal pathway that is modulated when the uterus’s sensory neurons detect sex peptide. “Thanks to our work, we think the sex peptide signal goes to a region of the fly’s brain that is the homolog of the hypothalamus, which has been know for many years to be central in controlling sexual receptivity in vertebrates,” explains co-lead author Dr. Mark Palfreyman of the Research Institute of Molecular Pathology in Vienna, Austria. This region of the brain links the nervous system to the endocrine, or hormonal, system. “Of course, these models will still need to be tested and our work only provides an initial glimpse, but our study opens the possibility that analogous neuroendocrine systems control sexual receptivity from flies to vertebrates,” adds senior author Dr. Barry Dickson, who was also a co-author on the Current Biology paper published by Dr. Vosshall.
Only 25 Minutes of Mindfulness Meditation Alleviates Stress
Mindfulness meditation has become an increasingly popular way for people to improve their mental and physical health, yet most research supporting its benefits has focused on lengthy, weeks-long training programs.
New research from Carnegie Mellon University is the first to show that brief mindfulness meditation practice — 25 minutes for three consecutive days — alleviates psychological stress. Published in the journal “Psychoneuroendocrinology,” the study investigates how mindfulness meditation affects people’s ability to be resilient under stress.
"More and more people report using meditation practices for stress reduction, but we know very little about how much you need to do for stress reduction and health benefits," said lead author J. David Creswell, associate professor of psychology in the Dietrich College of Humanities and Social Sciences.
For the study, Creswell and his research team had 66 healthy individuals aged 18-30 years old participate in a three-day experiment. Some participants went through a brief mindfulness meditation training program; for 25 minutes for three consecutive days, the individuals were given breathing exercises to help them monitor their breath and pay attention to their present moment experiences. A second group of participants completed a matched three-day cognitive training program in which they were asked to critically analyze poetry in an effort to enhance problem-solving skills.
Following the final training activity, all participants were asked to complete stressful speech and math tasks in front of stern-faced evaluators. Each individual reported their stress levels in response to stressful speech and math performance stress tasks, and provided saliva samples for measurement of cortisol, commonly referred to as the stress hormone.
The participants who received the brief mindfulness meditation training reported reduced stress perceptions to the speech and math tasks, indicating that the mindfulness meditation fostered psychological stress resilience. More interestingly, on the biological side, the mindfulness meditation participants showed greater cortisol reactivity.
"When you initially learn mindfulness mediation practices, you have to cognitively work at it — especially during a stressful task," said Creswell. "And, these active cognitive efforts may result in the task feeling less stressful, but they may also have physiological costs with higher cortisol production."
Creswell’s group is now testing the possibility that mindfulness can become more automatic and easy to use with long-term mindfulness meditation training, which may result in reduced cortisol reactivity.
Study Identifies Predictors for Teen Binge-Drinking
Neuroscientists leading the largest longitudinal adolescent brain imaging study to date have learned that predicting teenage binge-drinking is possible. In fact, say the researchers in the group’s latest publication, a number of factors – genetics, brain function and about 40 different variables – can help scientists predict with about 70 percent accuracy which teens will become binge drinkers. The study appears online July 3, 2014 as an Advance Online Publication in the journal Nature.
First author Robert Whelan, Ph.D., a former University of Vermont (UVM) postdoctoral fellow in psychiatry and current lecturer at University College Dublin, and senior author Hugh Garavan, Ph.D., UVM associate professor of psychiatry, and colleagues conducted 10 hours of comprehensive assessments – these included neuroimaging to assess brain activity and brain structure, along with other measures such as IQ, cognitive task performance, personality and blood tests – on each of 2,400 14-year-old adolescents at eight different sites across Europe.
“Our goal was to develop a model to better understand the relative roles of brain structure and function, personality, environmental influences and genetics in the development of adolescent abuse of alcohol,” says Whelan. “This multidimensional risk profile of genes, brain function and environmental influences can help in the prediction of binge drinking at age 16 years.”
A 2012 Nature Neuroscience paper by the same researchers identified brain networks that predisposed some teens to higher-risk behaviors like experimentation with drugs and alcohol. This new study develops on that earlier work by following those kids for years (the participants in the study are now 19 years old) and identifying those who developed a pattern of binge-drinking. The 2014 Nature study aimed to predict those who went on to drink heavily at age 16 using only data collected at age 14. They applied a broad range of measures, developing a unique analytic method to predict which individuals would become binge-drinkers. The reliability of the results were confirmed by showing the same accuracy when tested on a new, separate group of teenagers. The result was a list of predictors that ranged from brain and genetics to personality and personal history factors.
“Notably, it’s not the case that there’s a single one or two or three variables that are critical,” says Garavan. “The final model was very broad – it suggests that a wide mixture of reasons underlie teenage drinking.”
Some of the best predictors, shares Garavan, include variables like personality, sensation-seeking traits, lack of conscientiousness, and a family history of drug use. Having even a single drink at age 14, was also a powerful predictor. That type of risk-taking behavior – and the impulsivity that often accompanies it – was a critical predictor. In addition, those teens who had experienced several stressful life events were among those at greater risk for binge-drinking.
One interesting finding, says Garavan, was that bigger brains were also predictive. Adolescents undergo significant brain changes, so in addition to the formation of personalities and social networks, it’s actually normal for their brains to reduce to a more efficient size.
“There’s refining and sculpting of the brain, and most of the gray matter – the neurons and the connections between them, are getting smaller and the white matter is getting larger,” he explains. “Kids with more immature brains – those that are still larger – are more likely to drink.”
Garavan, Whelan and colleagues believe that by better understanding the probable causal factors for binge-drinking, targeted interventions for those most at risk could be applied.
Gunter Schumann, M.D.,professor of biological psychiatry and head of the section at the Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, King’s College London, is the principle investigator of the IMAGEN study, which is the source of this latest paper. “We aimed to develop a ‘gold standard’ model for predicting teenage behavior, which can be used as a benchmark for the development of simpler, widely applicable prediction models,” says Schumann. “This work will inform the development of specific early interventions in carriers of the risk profile to reduce the incidence of adolescent substance abuse. We now propose to extend analysis of the IMAGEN data in order to investigate the development of substance use patterns in the context of moderating environmental factors, such as exposure to nicotine or drugs as well as psychosocial stress.”
In the future, the researchers hope to perform more in-depth analyses of the brain factors involved and determine whether or not there are different predictors for abuse of other drugs. A similar analysis, which is using the same dataset to look at the predictors of cannabis use, is planned for the near future.
(Source: uvm.edu)
New study discovers biological basis for magic mushroom ‘mind expansion’
Psychedelic drugs such as LSD and magic mushrooms can profoundly alter the way we experience the world but little is known about what physically happens in the brain. New research, published in Human Brain Mapping, has examined the brain effects of the psychedelic chemical in magic mushrooms, called psilocybin, using data from brain scans of volunteers who had been injected with the drug.
The study found that under psilocybin, activity in the more primitive brain network linked to emotional thinking became more pronounced, with several different areas in this network - such as the hippocampus and anterior cingulate cortex - active at the same time. This pattern of activity is similar to the pattern observed in people who are dreaming. Conversely, volunteers who had taken psilocybin had more disjointed and uncoordinated activity in the brain network that is linked to high-level thinking, including self-consciousness.
Psychedelic drugs are unique among other psychoactive chemicals in that users often describe ‘expanded consciousness,’ including enhanced associations, vivid imagination and dream-like states. To explore the biological basis for this experience, researchers analysed brain imaging data from 15 volunteers who were given psilocybin intravenously while they lay in a functional magnetic resonance imaging (fMRI) scanner. Volunteers were scanned under the influence of psilocybin and when they had been injected with a placebo.
“What we have done in this research is begin to identify the biological basis of the reported mind expansion associated with psychedelic drugs,” said Dr Robin Carhart-Harris from the Department of Medicine, Imperial College London. “I was fascinated to see similarities between the pattern of brain activity in a psychedelic state and the pattern of brain activity during dream sleep, especially as both involve the primitive areas of the brain linked to emotions and memory. People often describe taking psilocybin as producing a dream-like state and our findings have, for the first time, provided a physical representation for the experience in the brain.”
The new study examined variation in the amplitude of fluctuations in what is called the blood-oxygen level dependent (BOLD) signal, which tracks activity levels in the brain. This revealed that activity in important brain networks linked to high-level thinking in humans becomes unsynchronised and disorganised under psilocybin. One particular network that was especially affected plays a central role in the brain, essentially ‘holding it all together’, and is linked to our sense of self.
In comparison, activity in the different areas of a more primitive brain network became more synchronised under the drug, indicating they were working in a more co-ordinated, ‘louder’ fashion. The network involves areas of the hippocampus, associated with memory and emotion, and the anterior cingulate cortex which is related to states of arousal.
Lead author Dr Enzo Tagliazucchi from Goethe University, Germany said: “A good way to understand how the brain works is to perturb the system in a marked and novel way. Psychedelic drugs do precisely this and so are powerful tools for exploring what happens in the brain when consciousness is profoundly altered. It is the first time we have used these methods to look at brain imaging data and it has given some fascinating insight into how psychedelic drugs expand the mind. It really provides a window through which to study the doors of perception.”
Dr. Carhart-Harris added: “Learning about the mechanisms that underlie what happens under the influence of psychedelic drugs can also help to understand their possible uses. We are currently studying the effect of LSD on creative thinking and we will also be looking at the possibility that psilocybin may help alleviate symptoms of depression by allowing patients to change their rigidly pessimistic patterns of thinking. Psychedelics were used for therapeutic purposes in the 1950s and 1960s but now we are finally beginning to understand their action in the brain and how this can inform how to put them to good use.”
The data was originally collected at Imperial College London in 2012 by a research group led by Dr Carhart-Harris and Professor David Nutt from the Department of Medicine, Imperial College London. Initial results revealed a variety of changes in the brain associated with drug intake. To explore the data further Dr. Carhart-Harris recruited specialists in the mathematical modelling of brain networks, Professor Dante Chialvo and Dr Enzo Tagliazucchi to investigate how psilocybin alters brain activity to produce its unusual psychological effects.
As part of the new study, the researchers applied a measure called entropy. This was originally developed by physicists to quantify lost energy in mechanical systems, such as a steam engine, but entropy can also be used to measure the range or randomness of a system. For the first time, researchers computed the level of entropy for different networks in the brain during the psychedelic state. This revealed a remarkable increase in entropy in the more primitive network, indicating there was an increased number of patterns of activity that were possible under the influence of psilocybin. It seemed the volunteers had a much larger range of potential brain states that were available to them, which may be the biophysical counterpart of ‘mind expansion’ reported by users of psychedelic drugs.
Previous research has suggested that there may be an optimal number of dynamic networks active in the brain, neither too many nor too few. This may provide evolutionary advantages in terms of optimising the balance between the stability and flexibility of consciousness. The mind works best at a critical point when there is a balance between order and disorder and the brain maintains this optimal number of networks. However, when the number goes above this point, the mind tips into a more chaotic regime where there are more networks available than normal. Collectively, the present results suggest that psilocybin can manipulate this critical operating point.
Short sleep, aging brain
Researchers at Duke-NUS Graduate Medical School Singapore (Duke-NUS) have found evidence that the less older adults sleep, the faster their brains age. These findings, relevant in the context of Singapore’s rapidly ageing society, pave the way for future work on sleep loss and its contribution to cognitive decline, including dementia.
Past research has examined the impact of sleep duration on cognitive functions in older adults. Though faster brain ventricle enlargement is a marker for cognitive decline and the development of neurodegenerative diseases such as Alzheimer’s, the effects of sleep on this marker have never been measured.
The Duke-NUS study examined the data of 66 older Chinese adults, from the Singapore-Longitudinal Aging Brain Study(1). Participants underwent structural MRI brain scans measuring brain volume and neuropsychological assessments testing cognitive function every two years. Additionally, their sleep duration was recorded through a questionnaire. Those who slept fewer hours showed evidence of faster ventricle enlargement and decline in cognitive performance.
"Our findings relate short sleep to a marker of brain aging," said Dr June Lo, the lead author and a Duke-NUS Research Fellow. "Work done elsewhere suggests that seven hours a day(2) for adults seems to be the sweet spot for optimal performance on computer based cognitive tests. In coming years we hope to determine what’s good for cardio-metabolic and long term brain health too," added Professor Michael Chee, senior author and Director of the Centre for Cognitive Neuroscience at Duke-NUS.
(Source: eurekalert.org)