Posts tagged neuroscience
Articles and news from the latest research reports.
How Different Nerve Cells Develop in the Eye
Neurobiologists from Heidelberg University’s Centre for Organismal Studies (COS) have gained new insights into how different types of nerve cells are formed in the developing animal. Through specialised microscopes, they were able to follow the development of the neural retina in the eye of living zebrafish embryos. Using high-resolution three-dimensional time-lapse images the researchers simultaneously observed the division of retinal nerve cells and changes in gene expression. This enabled them to gain insights into the way in which the two processes are linked during eye development and how the number and proportion of different cell types are regulated.
A central question in developmental and regenerative neurobiology concerns the growth processes in animal organisms: How does a growing animal control the generation of the right number of each type and subtype of nerve cell in the brain and what is the relationship between these cells? The retina consists of many different kinds of nerve cells, which are well characterised and common to all vertebrates. Thus, the retina is a particularly good model for studying neuronal development. The researchers studied such retinal developmental processes in living organisms using zebrafish embryos, which are completely transparent and grow rapidly outside their mother.
All retinal cells, which are either excitatory or inhibitory, arise from a relatively small number of apparently homogeneous progenitor cells. These progenitors are able to generate all the different retinal cell types. “It is a challenge to understand how each progenitor cell contributes to the correct number and subtype of nerve cells that compose the final retinal network. Our work contributes to the understanding of how different genes orchestrate neuronal diversity along a progenitor cell lineage, that is the number of cell divisions and types of neurons generated”, says Heidelberg researcher Dr. Lucia Poggi.
To tackle this challenge, Dr. Poggi’s team used different lines of transgenic zebrafish, in which fluorescent reporter proteins highlight the expression of different genes in dividing cells. Working in close cooperation with Dr. Patricia Jusuf of the Australian Regenerative Medicine Institute at Monash University, the researchers found that some particular kinds of excitatory and inhibitory nerve cells tend to be lineally related, i.e. they derive from a common progenitor cell. For the first time, 4D recordings permitted an in vivo analysis of how the generation of particular inhibitory cells is regulated through coordination of cell division mode and gene expression within individual retinal progenitors of excitatory nerve cells.
This study has established a model of how cell lineage influences neuronal subtype specification and neuronal circuitry formation in the native environment of the vertebrate brain. The results were published in the Journal of Neuroscience.
(Source: uni-heidelberg.de)
Turning urine into brain cells
Chinese researchers have devised a new technique for reprogramming cells from human urine into immature brain cells that can form multiple types of functioning neurons and glial cells. The technique, published in the journal Nature Methods, could prove useful for studying the cellular mechanisms of neurodegenerative conditions such as Alzheimer’s and Parkinson’s and for testing the effects of new drugs that are being developed to treat them.
Stem cells offer the hope of treating these debilitating diseases, but obtaining them from human embryos poses an ethical dilemma. We now know that cells taken from the adult human body can be made to revert to a stem cell-like state and then transformed into virtually any other type of cell. This typically involves using genetically engineered viruses that shuttle control genes into the nucleus and inserts them into the chromosomes, whereupon they activate genes that make them pluripotent, or able to re-differentiate into another type of cell.
In 2008, for example, American researchers took skin cells from an 82-year-old patient with amyotrophic lateral sclerosis and reprogrammed them into motor neurons. Cells obtained in this way could help us gain a better understanding of such diseases. Grafts of patients’ own cells do not elicit an immune response, so this approach may eventually lead to effective cell transplantation therapies. But it also has its problems – it appears that the reprogramming process destabilizes the genome and causes mutations, and that iPSCs may therefore harbour genetic defects that render them useless.
Last year, Duanqing Pei of the Chinese Academy of Sciences and his colleagues reported that human urine contains skin-like cells from the lining of the kidney tubules which can be efficiently reprogrammed, via the pluripotent state, into neurons, glia, liver cells and heart muscle cells. Now they have improved on the approach, making it quicker, more efficient and possibly less prone to errors.
In the new study, they isolated cells from urine samples given by three donors, aged 10, 25 and 37, and converted them directly into neural progenitors. They then grew these cells in Petri dishes and drove them to differentiate into mature neurons that can generate nervous impulses, and also into astrocytes and oligodendrocytes, two types of glial cell found in the human brain. Finally, they transplanted the re-programmed neurons and astrocytes into the brains of newborn rats, and found that the cells had survived when they examined the brains a month later, but it remains to be seen if they can survive for longer, and if they integrate into the existing circuits to be become functional.
This isn’t the first time that one type of cell has been converted into another without going through the pluripotent stage – in 2010, researchers from Stanford converted mouse connective tissue cells directly into neurons. The new technique does have a number of advantages, however.
Instead of using a virus to deliver the reprogramming genes, the researchers used a small circular piece of bacterial DNA which can replicate in the cytoplasm. This not only speeds up the process, but also eliminates the need to integrate the reprogramming genes into the chromosome, which is one potential source of genetic mutation, but it’s still not clear whether these cells contain fewer mutations than those reprogrammed using viruses.
Even so, the technique also makes the procedure of generating iPSCs far easier and non-invasive, as the cells can be obtained from a urine sample instead of a blood sample or biopsy. The next logical step will be to generate neurons from urine samples obtained from patients with Alzheimer’s, Parkinson’s, and other neurodegenerative diseases and to determine the extent to which this new non-viral technique damages the DNA.
(Source: Guardian)
In an article published online this week in the journal Nature, the UCSF team has identified the exact subset of nerve cells responsible for communicating gentle touch to the brains of Drosophila larvae—called class III neurons. They also uncovered a particular protein called NOMPC, which is found abundantly at the spiky ends of the nerves and appears to be critical for sensing gentle touch in flies.Without this key molecule, the team discovered, flies are insensitive to any amount of eyelash stroking, and if NOMPC is inserted into neurons that cannot sense gentle touch, those neurons gain the ability to do so.
“NOMPC is sufficient to confer sensitivity to gentle touch,” said Yuh Nung Jan, PhD, a professor of physiology, biochemistry and biophysics and a Howard Hughes Medical Institute investigator at UCSF. Jan led the study with his wife Lily Jan, PhD, who is also a UCSF professor and a Howard Hughes Medical Institute investigator.
The work sheds light on a poorly understood yet fundamental sense through which humans experience the world and derive pleasure and comfort.
Why is Touch Still Such a Mystery?
Scientists generally feel that, like those other senses, the sense of touch is governed by peripheral nerve fibers stretching from the spine to nerve endings all over the body. Special molecules in these nerve endings detect the mechanical movement of the skin surrounding them when it is touched, and they respond by opening and allowing ions to rush in. The nerve cell registers this response, and if the signal is strong enough, it will fire, signaling the gentle touch to the brain.
What has been missing from the picture, however, are the details of this process. The new finding is a milestone in that it defines the exact nerves and uncovers the identity of the NOMPC channel, one of the major molecular players involved—at least in flies.
Jan and his colleagues made this discovery through an unusual route. They were looking at the basic physiology of the developing fruit fly, examining how class III neurons develop in larvae. They noticed that when these cells developed in the insects, their nerve endings would always become branches into spiky “dendrites.”
Wanting to know what these neurons are responsible for, they examined them closely and found the protein NOMPC was abundant at the spiky ends. They then examined a fly genetically engineered to have a non-functioning form of NOMPC and showed that it was insensitive to gentle touch. They also showed that they could induce touch sensitivity in neurons that do not normally respond to gentle touch by inserting copies of the NOMPC protein into them.
(Image: Dietrich Meyer)
Brain study shows why some people are more in tune with what they want
Wellcome Trust researchers have discovered how the brain assesses confidence in its decisions. The findings explain why some people have better insight into their choices than others.
Throughout life, we’re constantly evaluating our options and making decisions based on the information we have available. How confident we are in those decisions has clear consequences. For example, investment bankers have to be confident that they’re making the right choice when deciding where to put their clients’ money.
Researchers at the Wellcome Trust Centre for Neuroimaging at UCL led by Professor Ray Dolan have pinpointed the specific areas of the brain that interact to compute both the value of the choices we have in front of us and our confidence in those choices, giving us the ability to know what we want.
The team used functional magnetic resonance imaging (fMRI) to measure activity in the brains of twenty hungry volunteers while they made choices between food items that they would later eat. To determine the subjective value of the snack options, the participants were asked to indicate how much they would be willing to pay for each snack. Then after making their choice, they were asked to report how confident they were that they had made the right decision and selected the best snack.
It has previously been shown that a region at the front of the brain, the ventromedial prefrontal cortex, is important for working out the value of decision options. The new findings reveal that the level of activity in this area is also linked to the level of confidence participants placed on choosing the best option. The study also shows that the interaction between this area of the brain and an adjacent area reflects participants’ ability to access and report their level of confidence in their choices.
Dr Steve Fleming, a Sir Henry Wellcome Postdoctoral Fellow now based at New York University, explains: “We found that people’s confidence varied from decision to decision. While we knew where to look for signals of value computation, it was very interesting to also observe neural signals of confidence in the same brain region.”
Dr Benedetto De Martino, a Sir Henry Wellcome Postdoctoral Fellow at UCL, added: “Overall, we think our results provide an initial account both of how people make choices, and also their insight into the decision process.”
(Source: eurekalert.org)
Bryan Saunders, a performance and visual artist, undertook a high profile experiment in creativity, starting several years ago whereby, according to the artist, he created a series of self-portraits, each one done under the influence of a different substance—pretty much an A to Z assortment, from prescription meds like Abilify and Xanax to crystal meth. Over the weeks he’d create amazing pieces, suffer mild brain damage and end up hospitalized—all for the sake of art and creation.
Left brain people: process info in a linear manner, identify important details, are analytical, move in a sequential order, and use logic to solve problems.
Right brain people: process info holistically, see end results with clarity, are creative, move randomly form task to task, and use intuition to solve problems.
Why the Left-Brain Right-Brain Myth Will Probably Never Die?
The Science of Storytelling: Why Telling a Story is the Most Powerful Way to Activate Our Brains
We all enjoy a good story, whether it’s a novel, a movie, or simply something one of our friends is explaining to us. But why do we feel so much more engaged when we hear a narrative about events?
It’s in fact quite simple. If we listen to a powerpoint presentation with boring bullet points, a certain part in the brain gets activated. Scientists call this Broca’s area and Wernicke’s area. Overall, it hits our language processing parts in the brain, where we decode words into meaning. And that’s it, nothing else happens.
When we are being told a story, things change dramatically. Not only are the language processing parts in our brain activated, but any other area in our brain that we would use when experiencing the events of the story are too.
Exoskeleton suit gives man chance to walk again
Cutting edge technology has a Darien man taking miraculous steps.
He was paralyzed after he was struck by a car while riding his bike, training for an ironman four years ago.
Mike Loura was beaming as he was walking and showcasing this amazing robotic exoskeleton technology. He was doing something he never imagined he’d be able to do again.
"Ever since the accident all the doctors said you’re never going to walk again," Loura said.
However, the husband and father of two girls is walking again. Thursday was day 15, the day Loura strapped on the wearable robot, a breakthrough technology, but it’s the first time he’s taking steps for others to see.
"Every time I take a step I kinda have to balance myself in a certain position for the machine to know that it’s ready to take the next step," said Loura.
"It has an exoskeleton system with battery powered motor that allows someone who can’t feel and can’t move," said Dr. David Rosenblum, "who’s paralyzed, the ability to go from sit to stand to actually taking steps."
Dr. Rosenblum is the medical director of Rehabilitation at Gaylord Specialty Healthcare, the only center in Connecticut to offer the Ekso Bionics’ Robotic Exoskeleton technology to patients with spinal chord injuries.
"We’re using it as a tool to work on balance to get someone up and moving," said Dr. Rosenblum. "From a wellness perspective to improve their quality of life."
Proving that robots aren’t just for people any longer, African grey parrot, Pepper, has learned to drive a robot that was specially designed for him. Pepper, whose wing feathers are clipped to preventing him from flying around his humans’ house and destroying their things, now manipulates the joystick on his riding robot to guide it to where ever he wishes to go.
This robotic “bird buggy” was the brainchild of his human companion, Andrew Gray, a 29-year-old electrical and computer engineering graduate student at the University of Florida.
Scientists Identify Two Genes Essential for Breathing
A team of researchers at the New York University’s Langone Medical Center has discovered that two genes, called Hoxa5 and Hoxc5, play a critical role in establishing the neuronal circuits required for breathing. The discovery could help advance treatments for spinal cord injuries and neurodegenerative diseases.
The three-year study published in the journal Nature Neuroscience identifies a molecular code that distinguishes a group of muscle-controlling nerve cells collectively known as the phrenic motor column (PMC).
“These cells lie about halfway up the back of the neck, just above the fourth cervical vertebra, and are probably the most important motor neurons in your body,” explained senior author Prof Jeremy Dasen of the Howard Hughes Medical Institute.
Harming the part of the spinal cord where the PMC resides can instantly shut down breathing. But relatively little is known about what distinguishes PMC neurons from neighboring neurons, and how PMC neurons develop and wire themselves to the diaphragm in the fetus. The PMC cells relay a constant flow of electrochemical signals down their bundled axons and onto the diaphragm muscles, allowing the lungs to expand and relax in the natural rhythm of breathing.
“We now have a set of molecular markers that distinguish those cells from other populations of motor neurons, so that we can study them in detail and look for ways to selectively enhance their survival,” Prof Dasen said.