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Posts tagged "Neuroscience"


Schizophrenia: What’s in my head?

When she’s experiencing hallucinations, artist Sue Morgan feels compelled to draw; to ‘get it out of her head’. Sue was diagnosed with schizophrenia about 20 years ago. The drawing is therapeutic, but it’s also Sue’s way of expressing the complex and sometimes frightening secret world in her head. In this film Sue meets Sukhi Shergill, a clinician and researcher at the Institute of Psychiatry in London. He’s also making pictures, but using MRI to peer inside the brains of schizophrenia patients.

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Bioengineer Studying How the Brain Controls Movement

A University of California, San Diego research team led by bioengineer Gert Cauwenberghs is working to understand how the brain circuitry controls how we move. The goal is to develop new technologies to help patients with Parkinson’s disease and other debilitating medical conditions navigate the world on their own. Their research is funded by the National Science Foundation’s Emerging Frontiers of Research and Innovation program.

"Parkinson’s disease is not just about one location in the brain that’s impaired. It’s the whole body. We look at the problems in a very holistic way, combine science and clinical aspects with engineering approaches for technology," explains Cauwenberghs, a professor at the Jacobs School of Engineering and co-director of the Institute for Neural Computation at UC San Diego. "We’re using advanced technology, but in a means that is more proactive in helping the brain to get around some of its problems—in this case, Parkinson’s disease—by working with the brain’s natural plasticity, in wiring connections between neurons in different ways."

Outcomes of this research are contributing to the system-level understanding of human-machine interactions, and motor learning and control in real world environments for humans, and are leading to the development of a new generation of wireless brain and body activity sensors and adaptive prosthetics devices. Besides advancing our knowledge of human-machine interactions and stimulating the engineering of new brain/body sensors and actuators, the work is directly influencing diverse areas in which humans are coupled with machines. These include brain-machine interfaces and telemanipulation.


Researchers Show How Lost Sleep Leads to Lost Neurons
First report in preclincal study showing extended wakefulness can result in neuronal injury.
Most people appreciate that not getting enough sleep impairs cognitive performance. For the chronically sleep-deprived such as shift workers, students, or truckers, a common strategy is simply to catch up on missed slumber on the weekends. According to common wisdom, catch up sleep repays one’s “sleep debt,” with no lasting effects. But a new Penn Medicine study shows disturbing evidence that chronic sleep loss may be more serious than previously thought and may even lead to irreversible physical damage to and loss of brain cells. The research is published today in the Journal of Neuroscience.
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Researchers Show How Lost Sleep Leads to Lost Neurons

First report in preclincal study showing extended wakefulness can result in neuronal injury.

Most people appreciate that not getting enough sleep impairs cognitive performance. For the chronically sleep-deprived such as shift workers, students, or truckers, a common strategy is simply to catch up on missed slumber on the weekends. According to common wisdom, catch up sleep repays one’s “sleep debt,” with no lasting effects. But a new Penn Medicine study shows disturbing evidence that chronic sleep loss may be more serious than previously thought and may even lead to irreversible physical damage to and loss of brain cells. The research is published today in the Journal of Neuroscience.

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Flying Through Inner Space

It’s hard to truly see the brain. I don’t mean to simply see a three-pound hunk of tissue. I mean to see it in a way that offers a deep feel for how it works. That’s not surprising, given that the human brain is made up of over 80 billion neurons, each branching out to form thousands of connections to other neurons. A drawing of those connections may just look like a tangle of yarn.

As I wrote in the February issue of National Geographic, a number of neuroscientists are charting the brain now in ways that were impossible just a few years ago. And out of these surveys, an interesting new way to look at the brain is emerging. Call it the brain fly-through. The brain fly-through only became feasible once scientists started making large-scale maps of actual neurons in actual brains. Once they had those co-ordinates in three-dimensional space, they could program a computer to glide through it. The results are strangely hypnotic.

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Did That Just Happen? How Your Brain Alters Mental Timelines

It sounds like a scene from a detective novel: The witness sees a body falling from the window, and then hears a loud noise that sounds like the body hitting the ground. But what if the noise actually came before the fall?

Navigating through our memories of past events seems to be easy task, but we don’t always get it right. We might remember things that didn’t happen, and we can also get the time wrong. We may remember incidents as happening closer together or farther apart than they actually did, or even completely mess up the order of events,

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Scientists Discover a New Pathway for Fear Deep Within the Brain

‘Far-reaching’ neurons connect the amygdala with fear response center to control behavior.

Fear is primal. In the wild, it serves as a protective mechanism, allowing animals to avoid predators or other perceived threats. For humans, fear is much more complex. A normal amount keeps us safe from danger. But in extreme cases, like post-traumatic stress disorder (PTSD), too much fear can prevent people from living healthy, productive lives. Researchers are actively working to understand how the brain translates fear into action. Today, scientists at Cold Spring Harbor Laboratory (CSHL) announce the discovery of a new neural circuit in the brain that directly links the site of fear memory with an area of the brainstem that controls behavior.

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Human neural progenitor cells isolated under selective culture conditions from the developing human brain and directed through lineage differentiation. Neural progenitor cells are stained green; differentiated astrocytes are orange. Nuclei are stained blue. Image courtesy of the National Institute of Neurological Disorders and Stroke.

Protein Switch Dictates Cellular Fate: Stem Cell or Neuron

Researchers at the University of California, San Diego School of Medicine have discovered that a well-known protein has a new function: It acts in a biological circuit to determine whether an immature neural cell remains in a stem-like state or proceeds to become a functional neuron.

The findings, published in the February 13 online issue of Cell Reports, more fully illuminate a fundamental but still poorly understood cellular act – and may have significant implications for future development of new therapies for specific neurological disorders, including autism and schizophrenia.

Postdoctoral fellow Chih-Hong Lou, working with principal investigator Miles F. Wilkinson, PhD, professor in the Department of Reproductive Medicine and a member of the UC San Diego Institute for Genomic Medicine, and other colleagues, discovered that this critical biological decision is controlled by UPF1, a protein essential for the nonsense-mediated RNA decay (NMD) pathway.

NMD was previously established to have two broad roles. First, it is a quality control mechanism used by cells to eliminate faulty messenger RNA (mRNA) – molecules that help transcribe genetic information into the construction of proteins essential to life.  Second, it degrades a specific group of normal mRNAs.  The latter function of NMD has been hypothesized to be physiologically important, but until now it had not been clear whether this is the case.

Wilkinson and colleagues discovered that in concert with a special class of RNAs called microRNA, UPF1 acts as a molecular switch to determine when immature (non-functional) neural cells differentiate into non-dividing (functional) neurons. Specifically, UPF1 triggers the decay of a particular mRNA that encodes for a protein in the TGF-? signaling pathway that promotes neural differentiation.  By degrading that mRNA, the encoded protein fails to be produced and neural differentiation is prevented.  Thus, Lou and colleagues identified for the first time a molecular circuit in which NMD acts to drive a normal biological response.

NMD also promotes the decay of mRNAs encoding proliferation inhibitors, which Wilkinson said may explain why NMD stimulates the proliferative state characteristic of stem cells. 

“There are many potential clinical ramifications for these findings,” Wilkinson said. “One is that by promoting the stem-like state, NMD may be useful for reprogramming differentiated cells into stem cells more efficiently. 

“Another implication follows from the finding that NMD is vital to the normal development of the brain in diverse species, including humans.  Humans with deficiencies in NMD have intellectual disability and often also have schizophrenia and autism. Therapies to enhance NMD in affected individuals could be useful in restoring the correct balance of stem cells and differentiated neurons and thereby help restore normal brain function.”

Scientists watch glowing molecules form memories in real time

For the first time ever, neuroscientists have observed memory-forming molecules travel around the brain of a living animal. The unprecedented breakthrough is shedding light on how nerve cells make memories.

Prior to being able to recall — or more accurately, reconstruct — a memory, it has to be encoded and stored in the brain. It’s a complicated and dynamic process involving changes to molecular structures which alter synaptic transmissions between neurons. But watching this process in action is easier said than done.


Younger people have “high definition” memories

It’s not that younger people are able to remember more than older people. Their memories seem better because they are able to retrieve them in higher definition. So says Philip Ko of Vanderbilt University in the US, in a study that sheds light on how differences in the behavioral and neural activity of younger and older adults influence the different generations’ ability to store and recall memories. The findings appear in the journal Attention, Perception & Psychophysics, published by Springer.

Under the mentorship of Dr. Brandon Ally, Ko led the research team to focus on visual working memory, a person’s ability to briefly retain a limited amount of visual information in the absence of visual stimuli. Their examination of why this function is reduced during the course of healthy aging took the multiple stages of encoding, maintenance, and the retrieval of memorized information into account.

They ran 11 older adults of around 67 years of age and 13 younger adults of approximately 23 years of age through a task called ‘visual change detection.’ This task consisted of viewing two, three or four colored dots and memorizing their appearance. These dots disappeared, and then after a few seconds the participants were presented with a single dot appearing in one of the memorized colors or a new color. The accuracy of their response (‘same’ or ‘different’) was considered to reflect how well they memorized the colors. This accuracy of response is referred to as ‘behavioral measure.’ Electroencephalographic data was also collected from the participants as they performed the task for a neural measure of their memory capacity.

Dr. Ko found that while behavioral measures indicated a lower capacity in older adults than younger adults to memorize items, the neural measure of memory capacity was very similar in both groups. In other words, during the maintenance stage, both groups stored the same number of items. The study is the first to show that the behavioral and electrophysiological correlates in the working memory capacity of older adults can be dissociated.

The researchers suggest, however, that older adults store the items at a lower resolution than younger adults, resulting in impaired recollection. The consequence of these differences in resolution may be apparent during retrieval from visual working memory. Unlike older adults, younger adults may be able to use perceptual implicit memory, a different kind of visual memory, to give them a ‘boost’ when they are trying to retrieve the stored information.

“We don’t know why older adults perform poorly when their neural activity suggests their memory capacity is intact, but we have two leads,” Ko said. “First, further analysis of this current dataset and other studies from our laboratory suggest that older adults retrieve memories differently than younger adults. Second, there is emerging evidence from other labs suggesting that the quality of older adults’ memories is poorer than younger adults. In other words, while older adults might store the same number of items, their memory of each item is ‘fuzzier’ than that of younger adults.”

(via kenobi-wan-obi)


The Mysterious Neuroscience of Learning Automatic Skills

When you are typing away at your computer, you don’t know what your fingers are really doing.

That is the conclusion of a study conducted by a team of cognitive psychologists at Vanderbilt and Kobe universities. It found that skilled typists can’t identify the positions of many of the keys on the QWERTY keyboard and that novice typists don’t appear to learn key locations in the first place.

“This demonstrates that we’re capable of doing extremely complicated things without knowing explicitly what we are doing,” said Vanderbilt University graduate student Kristy Snyder, the first author of the study, which was conducted under the supervision of Centennial Professor of Psychology Gordon Logan.

A description of the research will appear in an upcoming issue of the journal Attention, Perception & Psychophysics, which recently posted it online.

The researchers recruited 100 university students and members from the surrounding community to participate in an experiment. The participants completed a short typing test. Then, they were shown a blank QWERTY keyboard and given 80 seconds to write the letters in the correct location. On average, they typed 72 words per minute, moving their fingers to the correct keys six times per second with 94 percent accuracy. By contrast, they could accurately place an average of only 15 letters on a blank keyboard.

The fact that the typists did so poorly at identifying the position of specific keys didn’t come as a surprise. For more than a century, scientists have recognized the existence of automatism: the ability to perform actions without conscious thought or intention. Automatic behaviors of this type are surprisingly common, ranging from tying shoelaces to making coffee to factory assembly-line work to riding a bicycle and driving a car. So scientists had assumed that typing also fell into this category, but had not tested it.

What did come as a surprise, however, was a finding that conflicts with the basic theory of automatic learning, which suggests that it starts out as a conscious process and gradually becomes unconscious with repetition. According to the widely held theory – primarily developed by studying how people learn to play chess – when you perform a new task for the first time, you are conscious of each action and store the details in working memory. Then, as you repeat the task, it becomes increasingly automatic and your awareness of the details gradually fades away. This allows you to think about other things while you are performing the task.

Given the prevalence of this “use it or lose it” explanation, the researchers were surprised when they found evidence that the typists never appear to memorize the key positions, not even when they are first learning to type.

“It appears that not only don’t we know much about what we are doing, but we can’t know it because we don’t consciously learn how to do it in the first place,” said Logan.

Evidence for this conclusion came from another experiment included in the study. The researchers recruited 24 typists who were skilled on the QWERTY keyboard and had them learn to type on a Dvorak keyboard, which places keys in different locations. After the participants developed a reasonable proficiency with the alternative keyboard, they were asked to identify the placement of the keys on a blank Dvorak keyboard. On average, they could locate only 17 letters correctly, comparable to participants’ performance with the QWERTY keyboard.

According to the researchers, the lack of explicit knowledge of the keyboard may be due to the fact that computers and keyboards have become so ubiquitous that students learn how to use them in an informal, trial-and-error fashion when they are very young.

“When I was a boy, you learned to type by taking a typing class and one of the first assignments was to memorize the keyboard,” Logan recalled.

(via kenobi-wan-obi)


Visual System ‘Prioritizes’ Information for Conscious Access

We are continuously flooded with sensory information from our physical environment – the sights, sounds, smells, feel of everything around us. We’re flooded with so much information, in fact, that we’re not consciously aware of much of it.

“Considering that people are continuously presented with vast amounts of sensory information, a system is needed to select and prioritize the most relevant information,” Surya Gayet and colleagues write.

The researchers surmised that, in the case of vision, visual working memory (VWM) may be that selection system.

Given that VWM is used to actively retain information for upcoming goal-directed behavior, it seems likely that it would also play a role in selecting the information that is relevant to, and prioritized for, conscious access. Gayet and colleagues investigated their hypothesis in a series of experiments.

In the crucial experiment, participants were shown two colored patches and were instructed to remember one of them. Participants then saw a target item, presented in the remembered color or the other color, in one eye. They were simultaneously presented with a dynamic pattern in the other eye.

The dynamic pattern had the effect of masking the target item, making it temporarily invisible to the participants. The researchers wanted to see how long it would take for the participants to detect the masked target.

Data showed that those targets that matched the color held in VWM reached visual awareness faster than targets of another color. And data from subsequent experiments confirmed the findings from the first.

Together, the findings suggest that the content of VWM can affect how visual information is processed, before it’s even accessible to conscious awareness

“The results of the present experiments suggest that VWM might well play [a selection] role in human consciousness,” Gayet and colleagues explain. “It funnels down the incoming sensory information to that which is relevant for imminent goal-directed behavior.”

According to the researchers, these findings shed light on a functional link between visual awareness and VWM:

“Whereas VWM is used to retain relevant visual information for imminent goal-directed behavior, visual awareness is needed to flexibly deal with incoming information to guide future behavior.”


How does complex behavior spontaneously emerge in the brain?

A spatial representation of the background [neuronal] avalanche activity in a circular culture with a 2.5-mm radius and density of 300 neurons per mm. Only the top 1% of the most active connections is shown. Different colors correspond to different neuron communities, according to a community detection algorithm.

Image Credit: Javier G. Orlandi, et al. ©2013 Macmillan Publishers Limited

Read more …


The pauses that refresh the memory

Sufferers of schizophrenia experience a broad gamut of symptoms, including hallucinations and delusions as well as disorientation and problems with learning and memory. This diversity of neurological deficits has made schizophrenia extremely difficult for scientists to understand, thwarting the development of effective treatments. A research team led by Susumu Tonegawa from the RIKEN–MIT Center for Neural Circuit Genetics has now revealed disruptions in the activity of particular clusters of neurons that might account for certain core symptoms of this disorder.

Tonegawa’s laboratory previously found that mice lacking the protein calcineurin in certain regions of the brain exhibit many behavioral deficits that are characteristic of schizophrenia. In their most recent study, the researchers sought out physiological alterations at the single-cell or circuit level that could connect the absence of the calcineurin protein in the brain with these behavioral impairments.

Their study focused on the hippocampus, a region of the brain associated with memory and spatial learning. Within the hippocampus, specialized ‘place cells’ switch on and off as an animal explores its environment. During subsequent periods of wakeful rest, these place cells continue to fire in patterns that essentially ‘replay’ recent wanderings, allowing the brain to build memories based on these experiences. The researchers used precisely positioned electrodes to measure differences in brain activity in these cells for normal mice and the calcineurin-deficient mouse model of schizophrenia.

Remarkably, essentially identical place-cell activity patterns were observed for both sets of mice during active exploration. Once the animals were at rest, however, the calcineurin-deficient mice displayed a dramatic increase in place-cell activity. In the normal hippocampus, the resting replay process depended on sequential activity from place cells corresponding to specific, real-world spatial coordinates. In contrast, this correlation was all but lost in the calcineurin-deficient mice (Fig. 1). Instead, these neurons often seemed to fire indiscriminately, creating high levels of ‘noise’ that overwhelmed actual location information and thwarted memory formation.

"Our study provides the first potential evidence of disorganized thinking processes in a schizophrenia model at the single-cell and circuit level," says Junghyup Suh, a member of Tonegawa’s research team. These findings fit with an emerging model that suggests that schizophrenic symptoms may arise from excess activation of brain regions within a ‘default mode network’—which includes the hippocampus—during wakeful rest. "Neurobiological approaches that can calm down the default mode network may therefore open up new avenues to alleviating symptoms or curing this mental disorder," says Suh.

Image1:  A map of neuronal activity during wakeful rest in calcineurin-deficient mice. In normal mice, the map reveals complex firing patterns, which are absent in this mouse model of schizophrenia.

The brain’s impressively accurate internal clock allows us to detect the passage of time, a skill essential for many critical daily functions. Without the ability to track elapsed time, our morning shower could continue indefinitely. … Neuroscientists believe that we have distinct neural systems for processing different types of time, for example, to maintain a circadian rhythm, to control the timing of fine body movements, and for conscious awareness of time passage. Until recently, most neuroscientists believed that this latter type of temporal processing – the kind that alerts you when you’ve lingered over breakfast for too long – is supported by a single brain system. However, emerging research indicates that the model of a single neural clock might be too simplistic. A new study … reveals that the brain may in fact have a second method for sensing elapsed time. What’s more, the authors propose that this second internal clock not only works in parallel with our primary neural clock, but may even compete with it.
Fascinating new research on the brain’s two clocks. Pair with the science of our internal time. (via explore-blog)

(via explore-blog)