Latest Posts by smparticle2 - Page 8

The U.S. Women’s Team win gold at the 2014 Nanning World Championships

New ways to mass produce human neurons for studying neuropsychiatric disorders

Scientists from Singapore have streamlined the process of using human stem cells to mass produce GABAergic neurons (GNs) in the laboratory. This new protocol provides scientists with a robust source of GNs to study many psychiatric and neurological disorders such as autism, schizophrenia, and epilepsy, which are thought to develop at least in part due to GN dysfunction.

GNs are inhibitory neurons that reduce neuronal activation, and make up roughly 20 per cent of the human brain. They work alongside excitatory neurons (ENs) to ensure balanced neural activity for normal brain function. The coordinated interplay between GNs and ENs orchestrate specific activation patterns in the brain, which are responsible for our behaviour, emotions, and higher reasoning. Functional impairment of GNs results in imbalanced neural activity, thereby contributing to the symptoms observed in many psychiatric disorders.

The availability of high quality, functional human GN populations would facilitate the development of good models for studying psychiatric disorders, as well as for screening drug effects on specific populations of neurons. Scientists worldwide have been hard at work trying to generate a consistent supply of GNs in the laboratory, but have been faced with many challenges. Protocols involving multiple complex stages, poor yield, and requiring a long time to generate mature and functional GNs are just some of the limitations encountered.

Many of these limitations have now been overcome by the development of a rapid and robust protocol to generate GNs from human pluripotent stem cells (hPSCs) in a single step. With the addition of a specific combination of factors, hPSCs turn into mature and functional GNs in a mere six – eight weeks. This is about two – three times faster than the 10 - 30 weeks required for previous protocols. In addition, this new protocol is highly efficient, with GNs making up more than 80 per cent of the final neuron population.

To develop this protocol, the team from Duke-NUS Medical School (Duke-NUS), A*STAR’s Genome Institute of Singapore (GIS) and the National Neuroscience Institute (NNI) first identified genetic factors involved in GN development in the brain. The team then tried many different combinations of these factors, and succeeded in confirming that mature and functional human GNs were indeed generated.

“Just like how a balance of Yin and Yang is needed in order to stay healthy, a balance of ENs and GNs is required for normal brain function. We now know a fair bit about ENs because we have good protocols to make them. However, we still know very little of the other player, the GNs, because current protocols do not work well. Yet, when these GNs malfunction our brain goes haywire,” commented Dr Alfred Sun, a Research Fellow at NNI and co-first author of the publication alongside Mr Qiang Yuan, an NUS Graduate School PhD student.

“Our quick, efficient and easy way to mass produce GNs for lab use is a game changer for neuroscience and drug discovery. With increased recognition of the essential role of GNs in almost all neurological and psychiatric diseases, we envisage our new method to be widely used to advance research and drug screening,” said Dr Shawn Je, Assistant Professor in the Neuroscience and Behavioural Disorders Programme at Duke-NUS, and senior author of the study.

The speed and efficiency of generating GNs with this new protocol provides researchers unprecedented access to the quantities of neurons necessary for studying the role of GNs in disease mechanisms. Drugs and small molecules may now be screened at an unparalleled rate to discover the next blockbuster treatment for autism, schizophrenia, and epilepsy.

Never be afraid to fail.

Watch all of ‘It’s Always Sunny in Philadelphia’s" Charlie Day’s inspiring commencement speech here.

“I want to empower women through dance. I think you can build confidence through movement. When a woman starts moving her body, and becomes comfortable with herself, and realizes that she can do the steps — it connects back to life. Because all of life is movement. Technically we’re dancing every day. And it doesn’t matter how you look. It matters how you move.”

Method of teaching.. method of communication

Study Finds Students Of All Races Prefer Teachers Of Color

Regardless of their own race, students had more favorable perceptions of teachers of color, according to a new study from New York University.

“You know, we’ve always had been nerds. I was a nerd in high school. I was like… I didn’t get beat up, I was invisible.”

Mulan (1998)

You can hold yourself back from the sufferings of the world, that is something you are free to do and it accords with your nature, but perhaps this very holding back is the one suffering you could avoid.

Franz Kafka (via man-of-prose)

Cathedrals Beach, Galicia

(Image caption: A new technique called magnified analysis of proteome (MAP), developed at MIT, allows researchers to peer at molecules within cells or take a wider view of the long-range connections between neurons. Credit: Courtesy of the researchers)

Imaging the brain at multiple size scales

MIT researchers have developed a new technique for imaging brain tissue at multiple scales, allowing them to peer at molecules within cells or take a wider view of the long-range connections between neurons.

This technique, known as magnified analysis of proteome (MAP), should help scientists in their ongoing efforts to chart the connectivity and functions of neurons in the human brain, says Kwanghun Chung, the Samuel A. Goldblith Assistant Professor in the Departments of Chemical Engineering and Brain and Cognitive Sciences, and a member of MIT’s Institute for Medical Engineering and Science (IMES) and Picower Institute for Learning and Memory.

“We use a chemical process to make the whole brain size-adjustable, while preserving pretty much everything. We preserve the proteome (the collection of proteins found in a biological sample), we preserve nanoscopic details, and we also preserve brain-wide connectivity,” says Chung, the senior author of a paper describing the method in the July 25 issue of Nature Biotechnology.

The researchers also showed that the technique is applicable to other organs such as the heart, lungs, liver, and kidneys.

The paper’s lead authors are postdoc Taeyun Ku, graduate student Justin Swaney, and visiting scholar Jeong-Yoon Park.

Multiscale imaging

The new MAP technique builds on a tissue transformation method known as CLARITY, which Chung developed as a postdoc at Stanford University. CLARITY preserves cells and molecules in brain tissue and makes them transparent so the molecules inside the cell can be imaged in 3-D. In the new study, Chung sought a way to image the brain at multiple scales, within the same tissue sample.

“There is no effective technology that allows you to obtain this multilevel detail, from brain region connectivity all the way down to subcellular details, plus molecular information,” he says.

To achieve that, the researchers developed a method to reversibly expand tissue samples in a way that preserves nearly all of the proteins within the cells. Those proteins can then be labeled with fluorescent molecules and imaged.

The technique relies on flooding the brain tissue with acrylamide polymers, which can form a dense gel. In this case, the gel is 10 times denser than the one used for the CLARITY technique, which gives the sample much more stability. This stability allows the researchers to denature and dissociate the proteins inside the cells without destroying the structural integrity of the tissue sample.

Before denaturing the proteins, the researchers attach them to the gel using formaldehyde, as Chung did in the CLARITY method. Once the proteins are attached and denatured, the gel expands the tissue sample to four or five times its original size.

“It is reversible and you can do it many times,” Chung says. “You can then use off-the-shelf molecular markers like antibodies to label and visualize the distribution of all these preserved biomolecules.”

There are hundreds of thousands of commercially available antibodies that can be used to fluorescently tag specific proteins. In this study, the researchers imaged neuronal structures such as axons and synapses by labeling proteins found in those structures, and they also labeled proteins that allow them to distinguish neurons from glial cells.

“We can use these antibodies to visualize any target structures or molecules,” Chung says. “We can visualize different neuron types and their projections to see their connectivity. We can also visualize signaling molecules or functionally important proteins.”

High resolution

Once the tissue is expanded, the researchers can use any of several common microscopes to obtain images with a resolution as high as 60 nanometers — much better than the usual 200 to 250-nanometer limit of light microscopes, which are constrained by the wavelength of visible light. The researchers also demonstrated that this approach works with relatively large tissue samples, up to 2 millimeters thick.

“This is, as far as I know, the first demonstration of super-resolution proteomic imaging of millimeter-scale samples,” Chung says.

“This is an exciting advance for brain mapping, a technique that reveals the molecular and connectional architecture of the brain with unprecedented detail,” says Sebastian Seung, a professor of computer science at the Princeton Neuroscience Institute, who was not involved in the research.

Currently, efforts to map the connections of the human brain rely on electron microscopy, but Chung and colleagues demonstrated that the higher-resolution MAP imaging technique can trace those connections more accurately.

Chung’s lab is now working on speeding up the imaging and the image processing, which is challenging because there is so much data generated from imaging the expanded tissue samples.

“It’s already easier than other techniques because the process is really simple and you can use off-the-shelf molecular markers, but we are trying to make it even simpler,” Chung says.

Love this man.

Failing to find a single functioning stapler, the grad student struggles to keep things together.

Gone With The Wind

“It is the most passionate relationship of the film. It is almost equivalent to that of Scarlett O’hara and Ashley Wilkes and Scarlett and Rhett Butler. Mammy is Scarlett’s true mother. It is Mammy to whom Scarlett goes to for advice, it is Mammy who sees deeply into Scarlett’s emotions and knows everything that’s going on with her. Whereas Scarlett’s biological mother doesn’t understand the emotional turmoil of her daughter. This is an incredible performance, very inflictive, that unfortunately is never getting discussed these days because of the sensitivity we should properly feel.” -Camille Paglia

A rare screentest of Vivien Leigh and Clark Gable, just after Vivien had been announced as the official actress portraying Scarlett O’hara. A Selznick employee remembers, “Gable knew this was a woman’s picture and treated her with the utmost respect.”

“One of the things I always admired about Clark Gable was between scenes, he didn’t go lock himself up in his trailer. He would hang out with the guys, the electricians, they all loved him. He was not full of himself. It was nothing to come to set and find him straddling a bench, playing gim rummy with the crew.” -Ann Rutherford

Whistler, Canada

waaavess

New theory explains how beta waves arise in the brain

Beta rhythms, or waves of brain activity with an approximately 20 Hz frequency, accompany vital fundamental behaviors such as attention, sensation and motion and are associated with some disorders such as Parkinson’s disease. Scientists have debated how the spontaneous waves emerge, and they have not yet determined whether the waves are just a byproduct of activity, or play a causal role in brain functions. Now in a new paper led by Brown University neuroscientists, they have a specific new mechanistic explanation of beta waves to consider.

The new theory, presented in the Proceedings of the National Academy of Sciences, is the product of several lines of evidence: external brainwave readings from human subjects, sophisticated computational simulations and detailed electrical recordings from two mammalian model organisms.

“A first step to understanding beta’s causal role in behavior or pathology, and how to manipulate it for optimal function, is to understand where it comes from at the cellular and circuit level,” said corresponding author Stephanie Jones, research associate professor of neuroscience at Brown University. “Our study combined several techniques to address this question and proposed a novel mechanism for spontaneous neocortical beta. This discovery suggests several possible mechanisms through which beta may impact function.”

Making waves

The team started by using external magnetoencephalography (MEG) sensors to observe beta waves in the human somatosensory cortex, which processes sense of touch, and the inferior frontal cortex, which is associated with higher cognition.

They closely analyzed the beta waves, finding they lasted at most a mere 150 milliseconds and had a characteristic wave shape, featuring a large, steep valley in the middle of the wave.

The question from there was what neural activity in the cortex could produce such waves. The team attempted to recreate the waves using a computer model of a cortical circuitry, made up of a multilayered cortical column that contained multiple cell types across different layers. Importantly, the model was designed to include a cell type called pyramidal neurons, whose activity is thought to dominate the human MEG recordings.

They found that they could closely replicate the shape of the beta waves in the model by delivering two kinds of excitatory synaptic stimulation to distinct layers in the cortical columns of cells: one that was weak and broad in duration to the lower layers, contacting spiny dendrites on the pyramidal neurons close to the cell body; and another that was stronger and briefer, lasting 50 milliseconds (i.e., one beta period), to the upper layers, contacting dendrites farther away from the cell body. The strong distal drive created the valley in the waveform that determined the beta frequency.

Meanwhile they tried to model other hypotheses about how beta waves emerge, but found those unsuccessful.

With a model of what to look for, the team then tested it by looking for a real biological correlate of it in two animal models. The team analyzed measurements in the cortex of mice and rhesus macaques and found direct confirmation that this kind of stimulation and response occurred across the cortical layers in the animal models.

“The ultimate test of the model predictions is to record the electrical signals inside the brain,” Jones said. “These recordings supported our model predictions.”

Beta in the brain

Neither the computer models nor the measurements traced the source of the excitatory synaptic stimulations that drive the pyramidal neurons to produce the beta waves, but Jones and her co-authors posit that they likely come from the thalamus, deeper in the brain. Projections from the thalamus happen to be in exactly the right places needed to deliver signals to the right positions on the dendrites of pyramidal neurons in the cortex. The thalamus is also known to send out bursts of activity that last 50 milliseconds, as predicted by their theory.

With a new biophysical theory of how the waves emerge, the researchers hope the field can now investigate whether beta rhythms affect or merely reflect behavior and disease. Jones’s team in collaboration with Professor of Neuroscience Christopher Moore at Brown is now testing predictions from the theory that beta may decrease sensory or motor information processing functions in the brain. New hypotheses are that the inputs that create beta may also stimulate inhibitory neurons in the top layers of the cortex, or that they may may saturate the activity of the pyramidal neurons, thereby reducing their ability to process information; or that the thalamic bursts that give rise to beta occupy the thalamus to the point where it doesn’t pass information along to the cortex.

Figuring this out could lead to new therapies based on manipulating beta, Jones said.

“An active and growing field of neuroscience research is trying to manipulate brain rhythms for optimal function with stimulation techniques,” she said. “We hope that our novel finding on the neural origin of beta will help guide research to manipulate beta, and possibly other rhythms, for improved function in sensorimotor pathologies.”

“Conceited, spoiled, and arrogant- all of those things, of course, are true to the character. But she had courage and determination, and that, I think, is why women must secretly admire her.” -Vivien Leigh

“Before a scene, she would be muttering deprecations under her breath and making small moans. According to Vivien, the situation was stupid, the dialogue was silly, nobody could possibly believe the whole scene. And then…she would walk into the scene and do such a magnificent job that everybody on the set would be cheering.” -David O. Selznick