Posts tagged neuroscience
Articles and news from the latest research reports.
Why stem-cell science thrives in Japan
It’s easy to take for granted the epic scale of what some scientists are attempting these days. When the news broke a couple of weeks ago that Japanese scientists had turned normal cells from a mouse into eggs, and then fertilized them and seen them develop into baby mice, I thought it was pretty cool.
But I wasn’t that surprised.
I knew that Katsuhiko Hayashi — one of the scientists involved — was doing fascinating research on stem cells at Kyoto University, and so this seemed a natural progression for his work to take.
Then I spoke to him and his boss. What they said reminded me that they are attempting to do something that, until recently, would have blown the mind of almost any scientist, philosopher or other kind of intellectual there’s ever been throughout the whole of human history.
Mitinori Saitou, who is head of Hayashi’s lab at the Department of Anatomy and Cell Biology in the Graduate School of Medicine, was highly ambitious from an early age, and became particularly focused when he was doing his PhD as a young man.
"I got interested in germ-cell biology and the regulation of the cell fates," he told me, "hoping that one day it may be possible to develop a methodology to control cellular fate at will."
To control fate: It’s like something out of a Greek myth.
The Gambler’s Fallacy Is Associated with Weak Affective Decision Making but Strong Cognitive Ability
Humans demonstrate an inherent bias towards making maladaptive decisions, as shown by a phenomenon known as the gambler’s fallacy (GF). The GF has been traditionally considered as a heuristic bias supported by the fast and automatic intuition system, which can be overcome by the reasoning system. The present study examined an intriguing hypothesis, based on emerging evidence from neuroscience research, that the GF might be attributed to a weak affective but strong cognitive decision making mechanism. With data from a large sample of college students, we found that individuals’ use of the GF strategy was positively correlated with their general intelligence and executive function, such as working memory and conflict resolution, but negatively correlated with their affective decision making capacities, as measured by the Iowa Gambling Task. Our result provides a novel insight into the mechanisms underlying the GF, which highlights the significant role of affective mechanisms in adaptive decision-making.
BUSM Study Identifies Pathology of Huntington’s Disease
A study led by researchers at Boston University School of Medicine (BUSM) provides novel insight into the impact that Huntington’s disease has on the brain. The findings, published online in Neurology, pinpoint areas of the brain most affected by the disease and opens the door to examine why some people experience milder forms of the disease than others.
Richard Myers, PhD, professor of neurology at BUSM, is the study’s lead/corresponding author. This study, which is the largest to date of brains specific to Huntington’s disease, is the product of nearly 30 years of collaboration between the lead investigators at BUSM and their colleagues at the McLean Brain Tissue Resource Center, Massachusetts General Hospital and Columbia University.
Huntington’s disease (HD) is an inherited and fatal neurological disorder that typically is diagnosed when a person is approximately 40 years old. The gene responsible for the disease was identified in 1993, but the reason why certain neurons or brain cells die remains unknown.
The investigators examined 664 autopsy brain samples with HD that were donated to the McLean Brain Bank. They evaluated and scored more than 50 areas of the brain for the effects of HD on neurons and other brain cell types. This information was combined with a genetic study to characterize variations in the Huntington gene. They also gathered the clinical neurological information on the patients’ age when HD symptoms presented and how long the patient survived with the disease.
Based on this analysis, the investigators discovered that HD primarily damages the brain in two areas. The striatum, which is located deep within the brain and is involved in motor control and involuntary movement, was the area most severely impacted by HD. The outer cortical regions, which are involved in cognitive function and thought processing, also showed damage from HD, but it was less severe than in the striatum.
The investigators identified extraordinary variation in the extent of cell death in different brain regions. For example, some individuals had extremely severe outer cortical degeneration while others appeared virtually normal. Also, the extent of involvement for these two regions was remarkably unrelated, where some people demonstrated heavy involvement in the striatum but very little involvement in the cortex, and vice versa.
“There are tremendous differences in how people with Huntington’s disease are affected,” Myers said. “Some people with the disease have more difficulty with motor control than with their cognitive function while others suffer more from cognitive disability than motor control issues.”
When studying these differences, the investigators noted that the cell death in the striatum is heavily driven by the effects of variations in the Huntington gene itself, while effects on the cortex were minimally affected by the HD gene and are thus likely to be a consequence of other unidentified causes. Importantly, the study showed that some people with HD experienced remarkably less neuronal cell death than others.
“While there is just one genetic defect that causes Huntington’s disease, the disease affects different parts of the brain in very different ways in different people,” said Myers. “For the first time, we can measure these differences with a very fine level of detail and hopefully identify what is preventing brain cell death in some individuals with HD.”
The investigators have initiated extensive studies into what genes and other factors are associated with the protection of neurons in HD, and they hope these protective factors will point to possible novel treatments.
(Source: bumc.bu.edu)
Will Neuroscience Radically Transform the Legal System?
Although academic fields will often enjoy more than Andy Warhol’s famous 15 minutes of fame, they too are subject to today’s ever-hungry machinery of hype. Like people, bands, diets, and everything else, a field gets discovered, plucked from obscurity, thrown into the spotlight, and quickly replaced as it becomes yesterday’s news.
Neuroscience is now the popular plat de jour, or, perhaps better, the prefixde jour, and neurolaw is one of the main beneficiaries—and victims. Neuroscience will have important and even dramatic effects on our society and, as a result, on our laws. But not yet, and not as dramatically as some envision.
First, consider timing. Many of the most interesting neuroscience results come from functional magnetic resonance imaging (fMRI). This technique allows us to see what parts of the brain are working and when, and thus to begin to correlate subjective mental states with physical brain states. The use of fMRI on humans goes back about 15 years, and although about 5,000 peer-reviewed scientific articles involving fMRI will be published this year, we are still trying to figure out how it works—or doesn’t. The fMRI results showing apparently purposeful brain activity in dead salmon are a wonderfully funny example of some of the limits of this technology, and fMRI is one of the oldest of the “new” neuroscience technologies. Half of what neuroscience is teaching us about human brain function will be shown, in the next 20 years, to be wrong—and we will need each of those 20 years to figure out which half.
But, second, we need a sense of proportion. Neuroscience will provide tools that will change the law in some important ways, but those tools will be neither perfect nor used in isolation, and those changes are not likely to strike at the law’s roots.
Might lefties and righties benefit differently from a power nap?
At ‘rest,’ right hemisphere of the brain ‘talks’ more than the left hemisphere does
People who like to nap say it helps them focus their minds post a little shut eye. Now, a study from Georgetown University Medical Center may have found evidence to support that notion.
The research, presented at Neuroscience 2012, the annual meeting of the Society for Neuroscience, found that when participants in a study rested, the right hemisphere of their brains talked more to itself and to the left hemisphere than the left hemisphere communicated within itself and to the right hemisphere – no matter which of the participants’ hands was dominant. (Neuroscientists say right-handed people use their left hemisphere to a greater degree, and vice versa.)
Results of this study, the first known to look at activity in the two different hemispheres during rest, suggests that the right hemisphere “is doing important things in the resting state that we don’t yet understand,” says Andrei Medvedev, Ph.D., an assistant professor in the Center for Functional and Molecular Imaging at Georgetown. The activities being processed by the right hemisphere, which is known to be involved in creative tasks, could be daydreaming or processing and storing previously acquired information. “The brain could be doing some helpful housecleaning, classifying data, consolidating memories,” Medvedev says. “That could explain the power of napping. But we just don’t know yet the relative roles of both hemispheres in those processes and whether the power nap might benefit righties more then lefties.”
To find out what happens in the resting state, the research team connected 15 study participants to near-infrared spectroscopy (NIRS) equipment. This technology, which is low cost and portable, uses light to measure changes in oxygenated hemoglobin inside the body.
The study participants wore a cap adorned with optical fibers that delivers infrared light to the outermost layers of the brain and then measures the light that bounces back. In this way, the device can “see” which parts of the brain are most active and communicating at a higher level based on increased use of oxygen in the blood and heightened synchronicity of their activities.
"The device can help delineate global networks inside the brain — how the components all work together," Medvedev says. "The better integrated they are, the better cognitive tasks are performed."
To their surprise, the researchers found that left and right hemispheres behaved differently during the resting state. “That was true no matter which hand a participant used. The right hemisphere was more integrated in right-handed participants, and even stronger in the left-handed,” he says.
Medvedev is exploring the findings for an explanation. And he suggests that brain scientists should start focusing more of their attention on the right hemisphere. “Most brain theories emphasize the dominance of the left hemisphere especially in right handed individuals, and that describes the population of participants in these studies,” Medvedev says. “Our study suggests that looking at only the left hemisphere prevents us from a truer understanding of brain function.”
(Source: eurekalert.org)
Study clarifies process controlling night vision
New research reveals the key chemical process that corrects for potential visual errors in low-light conditions. Understanding this fundamental step could lead to new treatments for visual deficits, or might one day boost normal night vision to new levels.
Like the mirror of a telescope pointed toward the night sky, the eye’s rod cells capture the energy of photons - the individual particles that make up light. The interaction triggers a series of chemical signals that ultimately translate the photons into the light we see.
The key light receptor in rod cells is a protein called rhodopsin. Each rod cell has about 100 million rhodopsin receptors, and each one can detect a single photon at a time.
Scientists had thought that the strength of rhodopsin’s signal determines how well we see in dim light. But UC Davis scientists have found instead that a second step acts as a gatekeeper to correct for rhodopsin errors. The result is a more accurate reading of light under dim conditions.
A report on their research appears in the October issue of the journal Neuron in a study entitled “Calcium feedback to cGMP synthesis strongly attenuates single photon responses driven by long rhodopsin lifetimes.”
Using the Eye as a ‘Window Into the Brain’
An inexpensive, five-minute eye scan can accurately assess the amount of brain damage in people with the debilitating autoimmune disorder multiple sclerosis (MS), and offer clues about how quickly the disease is progressing, according to results of two Johns Hopkins studies.
“The eye is the window into the brain and by measuring how healthy the eye is, we can determine how healthy the rest of the brain is,” says Peter A. Calabresi, M.D., a professor of neurology at the Johns Hopkins University School of Medicine, and leader of the studies described in recent issues of The Lancet Neurology and the Archives of Neurology. “Eye scans are not that expensive, are really safe, and are widely used in ophthalmology, and now that we have evidence of their predictive value in MS, we think they are ready for prime time. We should be using this new quantitative tool to learn more about disease progression, including nerve damage and brain atrophy.”
Calabresi and his colleagues used optical coherence tomography (OCT) to scan nerves deep in the back of the eye, applying special software they co-developed that is capable of assessing previously immeasurable layers of the light-sensitive retinal tissue. The scan uses no harmful radiation and is one-tenth the cost of an MRI. The software will soon be widely available commercially.
The Neuronal Organization of the Retina
The mammalian retina consists of neurons of >60 distinct types, each playing a specific role in processing visual images. They are arranged in three main stages. The first decomposes the outputs of the rod and cone photoreceptors into ∼12 parallel information streams. The second connects these streams to specific types of retinal ganglion cells. The third combines bipolar and amacrine cell activity to create the diverse encodings of the visual world—roughly 20 of them—that the retina transmits to the brain. New transformations of the visual input continue to be found: at least half of the encodings sent to the brain (ganglion cell response selectivities) remain to be discovered. This diversity of the retina’s outputs has yet to be incorporated into our understanding of higher visual function.
Study finds association between rare neuromuscular disorder and loss of smell
Changes in the ability to smell and taste can be caused by a simple cold or upper respiratory tract infection, but they may also be among the first signs of neurodegenerative disorders such as Alzheimer’s disease and Parkinson’s disease. Now, new research from the Perelman School of Medicine at the University of Pennsylvania has revealed an association between an impaired sense of smell and myasthenia gravis (MG), a chronic autoimmune neuromuscular disease characterized by fluctuating fatigue and muscle weakness. The findings are published in the latest edition of PLOS ONE.
Most humans experience five types of tastes: sweet, salty, sour, bitter, and savory. The sense of taste is mediated by taste receptor cells which are bundled in our taste buds. “Sour” and “bitter” taste sensations alert the body to harmful foods that have spoiled or are toxic. But based on genetics, up to 25 percent of the population cannot detect certain bitter flavors (non-tasters), 25 percent can detect exceedingly small quantities (super-tasters), and the rest of us fall somewhere between these two extremes.
So what exactly does drinking a cup of bitter coffee have to do with chronic sinus infections, which account for approximately 18-22 million physician visits in the U.S. each year? Recent investigations have shown that these taste receptors (T2Rs) are also found in both upper and lower human respiratory tissue, likely signaling a connection between activation of bitter tastes and the need to launch an immune response in these areas when they are exposed to potentially harmful bacteria and viruses.
“With this information in mind, we wanted to better understand the exact role that bitter taste receptors play in the upper airway, especially between these super and non-tasters,” says Noam Cohen, MD, PhD, assistant professor of Otorhinolaryngology: Head and Neck Surgery, staff physician at the Philadelphia VAMC, and senior author of the new study.
(Source: medicalxpress.com)
Research discovers two opposite ways our brain voluntarily forgets unwanted memories
If only there were a way to forget that humiliating faux pas at last night’s dinner party. It turns out there’s not one, but two opposite ways in which the brain allows us to voluntarily forget unwanted memories, according to a study published by Cell Press October 17 in the journal Neuron. The findings may explain how individuals can cope with undesirable experiences and could lead to the development of treatments to improve disorders of memory control.
"This study is the first demonstration of two distinct mechanisms that cause such forgetting: one by shutting down the remembering system, and the other by facilitating the remembering system to occupy awareness with a substitute memory," says lead study author Roland Benoit of the MRC Cognition and Brain Sciences Unit at the University of Cambridge.
Previous studies have shown that individuals can voluntarily block memories from awareness. Although several neuroimaging studies have examined the brain systems involved in intentional forgetting, they have not revealed the cognitive tactics that people use or the precise neural underpinnings. Two possible ways to forget unwanted memories are to suppress them or to substitute them with more desirable memories, and these tactics could engage distinct neural pathways.
(Source: medicalxpress.com)