Posts tagged neuroscience
Articles and news from the latest research reports.
Study Confirms AKT1 Genotype Contributes to Risk of Cannabis Psychosis
The ability of cannabis to produce psychosis is an important public health concern. Some studies have suggested that cannabis exposure during adolescence may increase the risk of developing schizophrenia.
For these reasons, it would be valuable if a biological test could be developed that predicted the risk of developing psychosis in people who abuse cannabis or use marijuana as a medication.
A recent study has implicated a variation in the gene that codes for a protein called RAC-alpha serine/threonine-protein kinase in the risk for cannabis psychosis. However, independent verification of these finding is critical for genetic associations with complex genetic traits, like cannabis-related psychosis, because these findings are difficult to replicate.
Dr Forti’s team carried out a case control study to investigate variation in the AKT1 gene and cannabis use in increasing the risk of psychosis.
“We studied the AKT1 gene as this is involved in dopamine signaling which is known to be abnormal in psychosis. Our sample comprised 489 patients with their first episode of psychosis and 278 healthy controls,” explained Dr Forti, who, with colleagues, reports on the results in the journal Biological Psychiatry.
Worm Regeneration May Lend A Hand in Human Healing
About the size of toenail clippings, planarians are freshwater flatworms that can re-form from tiny slivers. This feature not only lets them repair themselves, but it lets them reproduce by breaking apart and then creating new worms.
Here are two other important features: More than half of planarian genes have parallels in people, and some of their basic physiological systems operate like ours. By studying how these features behave as the worms regenerate, scientists might move one step closer to learning how to generate or regenerate human tissue and cells, such as insulin-producing cells for people with diabetes or nerve cells for patients with spinal cord injuries.
Ever wondered what your brain sounds like? Now you can hear the sweet melody of the mind by listening to sound composed from an analysis of brain activity.
Engineering a Photo-Switch for Nerve Cells in the Eye and Brain
Chemists and vision scientists at the University of Illinois at Chicago have designed a light-sensitive molecule that can stimulate a neural response in cells of the retina and brain — a possible first step to overcoming degenerative eye diseases like age-related macular degeneration, or to quieting epileptic seizures.
Their results are reported online in the journal Nature Communications.
Macular degeneration, the leading cause of vision loss in people over 50, is caused by loss of light-sensitive cells in the retina — the rods and cones.
"The rods and cones, which absorb light and initiate visual signals, are the broken link in the chain, even though what we call the ‘inner cells’ of the retina, in many cases, are still potentially capable of function," says David Pepperberg, professor of ophthalmology and visual sciences in the UIC College of Medicine, the principal investigator on the study.
"Our approach is to bypass the lost rods and cones, by making the inner cells responsive to light."
Pepperberg and his colleagues are trying to develop light-sensitive molecules that — when injected into the eye — can find their way to inner retinal cells, attach themselves, and initiate the signal that is sent to the brain.
Could poor sleep contribute to symptoms of schizophrenia?
Neuroscientists studying the link between poor sleep and schizophrenia have found that irregular sleep patterns and desynchronised brain activity during sleep could trigger some of the disease’s symptoms. The findings, published in the journal Neuron, suggest that these prolonged disturbances might be a cause and not just a consequence of the disorder’s debilitating effects.
The possible link between poor sleep and schizophrenia prompted the research team, led by scientists from the University of Bristol, the Lilly Centre for Cognitive Neuroscience and funded by the Medical Research Council (MRC), to explore the impact of irregular sleep patterns on the brain by recording electrical brain activity in multiple brain regions during sleep.
For many people, sleep deprivation can affect mood, concentration and stress levels. In extreme cases, prolonged sleep deprivation can induce hallucinations, memory loss and confusion all of which are also symptoms associated with schizophrenia.
Dr Ullrich Bartsch, one of the study’s researchers, said: “Sleep disturbances are well-documented in the disease, though often regarded as side effects and poorly understood in terms of their potential to actually trigger its symptoms.”
Using a rat model of the disease, the team’s recordings showed desynchronisation of the waves of activity which normally travel from the front to the back of the brain during deep sleep. In particular the information flow between the hippocampus — involved in memory formation, and the frontal cortex — involved in decision-making, appeared to be disrupted. The team’s findings reported distinct irregular sleep patterns very similar to those observed in schizophrenia patients.
Dr Matt Jones, the lead researcher from the University’s School of Physiology and Pharmacology, added: “Decoupling of brain regions involved in memory formation and decision-making during wakefulness are already implicated in schizophrenia, but decoupling during sleep provides a new mechanistic explanation for the cognitive deficits observed in both the animal model and patients: sleep disturbances might be a cause, not just a consequence of schizophrenia. In fact, abnormal sleep patterns may trigger abnormal brain activity in a range of conditions.”
Cognitive deficits — reduced short term memory and attention span, are typically resistant to medication in patients. The findings from this study provide new angles for neurocognitive therapy in schizophrenia and related psychiatric diseases.
(Source: eurekalert.org)
Study links exposure to light at night to depression, learning issues
For most of history, humans rose with the sun and slept when it set. Enter Thomas Edison, and with a flick of a switch, night became day, enabling us to work, play, and post cat and kid photos on Facebook into the wee hours.
However, according to a new study led by a Johns Hopkins biologist, this typical 21st- century scenario comes at a serious cost: When people routinely burn the midnight oil, they risk suffering depression and learning issues, and not only because of lack of sleep. The culprit could also be exposure to bright light at night from lamps, computers, and even iPads.
"Basically, what we found is that chronic exposure to bright light—even the kind of light you experience in your own living room at home or in the workplace at night if you are a shift worker—elevates levels of a certain stress hormone in the body, which results in depression and lowers cognitive function,” said Samer Hattar, a biology professor in the Krieger School of Arts and Sciences.
The study, published in the Nov. 14 Advance Online Publication of the journal Nature, used mice to demonstrate how special cells in the eye (called intrinsically photosensitive retinal ganglion cells, or ipRGCs) are activated by bright light, affecting the brain’s center for mood, memory, and learning.
How Cells in the Nose Detect Odors
Now a team of scientists, led by neurobiologists at the University of California, Riverside, has an explanation. Focusing on the olfactory receptor for detecting carbon dioxide in Drosophila (fruit fly), the researchers identified a large multi-protein complex in olfactory neurons, called MMB/dREAM, that plays a major role in selecting the carbon dioxide receptors to be expressed in appropriate neurons.
Study results appear in the Nov. 15 issue of Genes & Development. The research is featured on the cover of the issue.
According to the researchers, a molecular mechanism first blocks the expression of most olfactory receptor genes (~60) in the fly’s antennae. This mechanism, which acts like a brake, relies on repressive histones —proteins that tightly wrap DNA around them. All insects and mammals are equipped with this mechanism, which keeps the large families of olfactory receptor genes repressed.
“How, then, do you release this brake so that only the carbon dioxide receptor is expressed in the carbon dioxide neuron while the remaining receptors are repressed?” said Anandasankar Ray, an assistant professor of entomology, whose lab conducted the research. “Our lab, in collaboration with a lab at Stanford University, has found that the MMB/dREAM multi-protein complex can act on the genes of the carbon dioxide receptors and de-repress the braking mechanism — akin to taking the foot off the brake pedal. This allows these neurons to express the receptors and respond to carbon dioxide.”
Ray explained that one way to understand the mechanism in operation is to consider a typewriter. When none of the keys are pressed, a spring mechanism or “brake” can be imagined to hold the type bars away from the paper. When a key is pressed, however, the brake on that key is overcome and the appropriate letter is typed onto the paper. And just as typing only one letter in one spot is important for each letter to be recognized, expressing one receptor in one neuron lets different sensor types to be generated in the nose.
Bonobos Catch Yawns from Friends
For bonobos, yawning is contagious, but only between friends.
Yawns spread more easily between family and close friends, and from high-status monkeys to those lower on the totem pole, according to a study published online in the journal PLoS ONE. This pattern of social yawning mimics one found in humans and suggests infectious yawning is a byproduct of empathy, which coordinates emotions in a group.
"It underlines that the mechanism of yawn contagion in the two species is the same," said study co-author Elisabetta Palagi, a primate researcher at the University of Pisa in Italy. "One of the possible functions of yawn contagion is to synchronize individuals of a social group. In humans, yawn contagion is extremely important but just between people who share strong bonds."
New brain gene born, study shows
Scientists have taken a step forward in helping to solve one of life’s greatest mysteries - what makes us human?
Image: Irish Wildcat
An international team of researchers have discovered a new gene that helps explain how humans evolved from apes. Scientists say the gene - calledmiR-941 - appears to have played a crucial role in human brain development and may shed light on how we learned to use tools and language. Researchers say it is the first time that a new gene - carried only by humans and not by apes - has been shown to have a specific function within the human body.
Unique finding
A team at the University of Edinburgh compared the human genome to 11 other species of mammals, including chimpanzees, gorillas, mouse and rat, to find the differences between them. The results, published in Nature Communications, showed that the gene - miR-941 - is unique to humans. The researchers say that it emerged between six and one million years ago, after humans had evolved from apes. The gene is highly active in two areas of the brain that control our decision making and language abilities. The study suggests it could have a role in the advanced brain functions that make us human.
Startling results
It is known that most differences between species occur as a result of changes to existing genes, or the duplication and deletion of genes. But scientists say this gene emerged fully functional out of non-coding genetic material, previously termed “junk DNA”, in a startlingly brief interval of evolutionary time. Until now, it has been remarkably difficult to see this process in action. Researcher Dr Martin Taylor, who led the study at the Institute of Genetics and Molecular Medicine at the University of Edinburgh, said the results were fascinating.
This new molecule sprang from nowhere at a time when our species was undergoing dramatic changes: living longer, walking upright, learning how to use tools and how to communicate. We’re now hopeful that we will find more new genes that help show what makes us human. -Dr Martin Taylor (Programme leader, Biomedical Systems Analysis)
(Source: ed.ac.uk)
Naturally, our brain activity waxes and wanes. When listening, this oscillation synchronizes to the sounds we are hearing. Researchers at the Max Planck Institute for Human Cognitive and Brain Sciences have found that this influences the way we listen. Hearing abilities also oscillate and depend on the exact timing of one’s brain rhythms. This discovery that sound, brain, and behaviour are so intimately coupled will help us to learn more about listening abilities in hearing loss.