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I think what Oliver Sacks wrote before his death sums life up perfectly.
bela homenagem. adoro esse cara. Remembering Oliver Sacks - Radiolab http://t.co/RLt46M2xVm
Dr. Oliver Sacks had many achievements, but letâs not forget his 600lbs squat.
âIn examining disease, we gain wisdom about anatomy and physiology and biology. In examining the person with disease, we gain wisdom about life."Â â Oliver Sacks
RIP Oliver Sacks. The world is a little less magical without you in it.Â
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High blood levels of growth factor correlate with smaller brain areas in patients with schizophrenia
High blood levels of a growth factor known to enable new blood vessel development and brain cell protection correlate with a smaller size of brain areas key to complex thought, emotion and behavior in patients with schizophrenia, researchers report in the journal Molecular Psychiatry.
Higher blood levels of vascular endothelial growth factor, or VEGF, also correlate with high blood levels of interleukin 6, a cytokine that can cross the protective blood-brain barrier and typically promotes inflammation, said Dr. Anilkumar Pillai, neuroscientist in the Department of Psychiatry and Health Behavior at the Medical College of Georgia at Georgia Regents University. As with many disease types, inflammation is increasingly associated with schizophrenia, and high blood levels of IL-6 already have been found in these patients.
The new findings appear to point toward a blood test as an easier way to confirm the diagnosis of schizophrenia, rather than complicated and expensive imaging studies of the brain, and, ultimately, better disease understanding and treatment, said Pillai, the studyâs corresponding author. âWe are talking about a molecule where you can just draw blood and look at the lab profile,â he said.
A smaller prefrontal cortex is one of the brain abnormalities identified through brain scans of living patients as well as autopsies. Pillaiâs lab had earlier shown low brain levels of VEGF, which could help explain lower blood flow and brain volumes in these patients. âDecreased blood flow leads to decreased brain tissue volume,â he said. Inflammation also can reduce brain size.
While findings of higher blood levels may sound counterintuitive to low VEGF levels in the brain, they likely indicate a âfeedback inhibitionâ with the brain recognizing high circulating levels and deciding to produce less VEGF itself, Pillai said. In fact, high blood levels of VEGF may contribute to the disease process, the researchers write.
More patients need to be studied to see if the correlations hold up, Pillai said, and work also is needed to determine which comes first: high blood levels or low brain levels of VEGF.
The study, in collaboration with scientists at the School of Psychiatry at the University of New South Wales in Australia, looked at 96 people with schizophrenia as well as 83 healthy individuals. Brain scans were available on 59 of the patients and 65 healthy controls. Patients were recruited to Neuroscience Research Australia, a not-for-profit research institution based in Sydney that focuses on the brain and nervous system, as well as Lyell McEwin Hospital, a teaching hospital in South Australia affiliated with the University of Adelaide and the University of South Australia.
While likely best known for its role in making new blood vessels, VEGF also is key to the brainâs ability to adapt to change, such as respond to an injury, and protect against brain cell loss.
Neuroscientists decipher brainâs noisy code
By analyzing the signals of individual neurons in animals undergoing behavioral tests, neuroscientists at Rice University, Baylor College of Medicine, the University of Geneva and the University of Rochester have deciphered the code the brain uses to make the most of its inherently ânoisyâ neuronal circuits.
The human brain contains about 100 billion neurons, and each of these sends signals to thousands of other neurons each second. Understanding how neurons work, both individually and collectively, is important to better understand how humans think, as well as to treat neurological and psychiatric disorders like Alzheimerâs disease, Parkinsonâs disease, autism, epilepsy, schizophrenia, depression, traumatic brain injury and paralysis.
âIf the brain could always count on receiving the same sensory response to the same stimulus, it would have an easier time,â said neuroscientist Xaq Pitkow, lead author of a new study in Neuron. âBut noise is always there in the brain: studies have repeatedly shown that neurons give a variety of responses to the same stimulus.â
Pitkow, assistant professor of neuroscience at Baylor and assistant professor of electrical and computer engineering at Rice, said ânoiseâ can be described as anything that changes neural activity in a way that doesnât depend on the task the brain wants to accomplish.
Not only are neural responses noisy, but each neuronâs noise is correlated with the noise in thousands of other neurons. That means that something that affects the output of one neuron may be amplified to affect many more. Because of these correlations, it is extraordinarily difficult for scientists to accurately model how small groups of neurons will affect the way a person or animal reacts to a given stimulus.
Given both these correlated responses and the inherently noisy nature of neuronal signals, scientists have struggled to explain a seeming paradox that was first observed in experiments more than 25 years ago.
âWhen neuroscientists first analyzed the output of individual neurons, they were surprised to find that the activity of just a single neuron sometimes predicted behavior in certain tasks,â Pitkow said.
This perplexing find has turned up in numerous experiments, but neuroscientists have yet to explain it.
âA lot of people have studied this and offered up different kinds of models that make all sorts of assumptions,â Pitkow said. âBy integrating all of those ideas and applying some analytical techniques, we found there were two different ways this could happen.â
He said one possibility is that many neurons are sharing the same information, processing it independently and arriving at the same answer. The other possibility is that each neuron is using different information and casting its vote for a slightly different answer but the brain is doing a poor job of coming to a consensus with the different votes.
âThe first model is a bit like trying to find a needle in haystack, and the second is like trying to find a needle on a clean floor while looking backward through a pair of binoculars,â Pitkow said. âEach piece of straw looks like a needle, which makes the haystack test very difficult. On the other hand, a needle should really stand out on a clean floor, but it will be hard to find with a bad searching method.â
In each case, the neurons are correlated with one other, âbut in the first instance the noise correlations can never be removed, and in the second they could and should be removed but theyâre not,â Pitkow said. âAnd each of these scenarios has very different consequences for the brainâs code, how it represents information. In terms of information theory, if the brain has a lot of information and it is not doing a good job of using it, there are very different implications than if all the neurons are correlated and theyâre all informative in the same way.â
To determine which of these scenarios is at play in the brain, Pitkow and colleagues developed two mathematical models, one for each scenario. The models described how information and noise would flow through the network in the two opposing cases.
The team tested each model against the activity of single neurons in monkeys that were undergoing perceptual tests to measure how accurately they could perceive slight movements to the left or right. The experimenters found that some neurons predicted the animalsâ guesses about whether they were moving left or right.
âWhen we examined the output, we found that the monkeysâ brains were not throwing away information,â Pitkow said. âThey were using each neuronâs information very effectively. And we also saw that even though there were many neurons involved, the guess of any individual neuron was only slightly worse than the animalâs actual guess during the test. These two pieces of evidence together indicate the neurons mostly share the same information.â
But if every neuron is doing the same processing, why have so many? Itâs an obvious question, Pitkow said, but itâs beyond the scope of what he and his colleagues could address in the current study.
âWe didnât explore the value of redundancy in this study, but we are very interested in that question,â Pitkow said. He pointed out that the vestibular sensors, the part of the inner ear dedicated to the sense of balance, contain only about 6,000 of the brainâs 100 billion neurons. Even those few thousand might be redundant, which would mean that the rest of the neurons they contact also are redundant.
âOne intriguing possibility that we are looking into is that redundancy allows the brain to reformat information and approach complex problems from many different angles,â he said.
Futuristic brain probe allows for wireless control of neurons
A Â study showed that scientists can wirelessly determine the path a mouse walks with a press of a button. Researchers at the Washington University School of Medicine, St. Louis, and University of Illinois, Urbana-Champaign, created a remote controlled, next-generation tissue implant that allows neuroscientists to inject drugs and shine lights on neurons deep inside the brains of mice. The revolutionary device is described online in the journal Cell. Its development was partially funded by the National Institutes of Health.
âIt unplugs a world of possibilities for scientists to learn how brain circuits work in a more natural setting.â said Michael R. Bruchas, Ph.D., associate professor of anesthesiology and neurobiology at Washington University School of Medicine and a senior author of the study.
The Bruchas lab studies circuits that control a variety of disorders including stress, depression, addiction, and pain. Typically, scientists who study these circuits have to choose between injecting drugs through bulky metal tubes and delivering lights through fiber optic cables. Both options require surgery that can damage parts of the brain and introduce experimental conditions that hinder animalsâ natural movements.
To address these issues, Jae-Woong Jeong, Ph.D., a bioengineer formerly at the University of Illinois at Urbana-Champaign, worked with Jordan G. McCall, Ph.D., a graduate student in the Bruchas lab, to construct a remote controlled, optofluidic implant. The device is made out of soft materials that are a tenth the diameter of a human hair and can simultaneously deliver drugs and lights.
âWe used powerful nano-manufacturing strategies to fabricate an implant that lets us penetrate deep inside the brain with minimal damage,â said John A. Rogers, Ph.D., professor of materials science and engineering, University of Illinois at Urbana-Champaign and a senior author. âUltra-miniaturized devices like this have tremendous potential for science and medicine.â
With a thickness of 80 micrometers and a width of 500 micrometers, the optofluidic implant is thinner than the metal tubes, or cannulas, scientists typically use to inject drugs. When the scientists compared the implant with a typical cannula they found that the implant damaged and displaced much less brain tissue.
The scientists tested the deviceâs drug delivery potential by surgically placing it into the brains of mice. In some experiments, they showed that they could precisely map circuits by using the implant to inject viruses that label cells with genetic dyes. In other experiments, they made mice walk in circles by injecting a drug that mimics morphine into the ventral tegmental area (VTA), a region that controls motivation and addiction.
The researchers also tested the deviceâs combined light and drug delivery potential when they made mice that have light-sensitive VTA neurons stay on one side of a cage by commanding the implant to shine laser pulses on the cells. The mice lost the preference when the scientists directed the device to simultaneously inject a drug that blocks neuronal communication. In all of the experiments, the mice were about three feet away from the command antenna.
âThis is the kind of revolutionary tool development that neuroscientists need to map out brain circuit activity,â said James Gnadt, Ph.D., program director at the NIHâs National Institute of Neurological Disorders and Stroke (NINDS). âItâs in line with the goals of the NIHâs BRAIN Initiative.â
The researchers fabricated the implant using semi-conductor computer chip manufacturing techniques. It has room for up to four drugs and has four microscale inorganic light-emitting diodes. They installed an expandable material at the bottom of the drug reservoirs to control delivery. When the temperature on an electric heater beneath the reservoir rose then the bottom rapidly expanded and pushed the drug out into the brain.
âWe tried at least 30 different prototypes before one finally worked,â said Dr. Â McCall.
âThis was truly an interdisciplinary effort,â said Dr. Jeong, who is now an assistant professor of electrical, computer, and energy engineering at University of Colorado Boulder. âWe tried to engineer the implant to meet some of neurosciences greatest unmet needs.â
In the study, the scientists provide detailed instructions for manufacturing the implant.
âA tool is only good if itâs used,â said Dr. Bruchas. âWe believe an open, crowdsourcing approach to neuroscience is a great way to understand normal and healthy brain circuitry.â
Tiny eye movements highlight the world around us
Without us being aware of it, our eyes constantly perform tiny corrections of their viewing direction. Until recently, the purpose of these corrections was not well understood. A group of TĂŒbingen researchers at the Werner Reichardt Centre for Integrative Neuroscience (CIN) and the Hertie Institute for Clinical Brain Research (HIH) has now tackled this problem. They have discovered a direct link between tiny eye movements and the focusing of attention needed to perceive our visual environment.
Our sensory organs constantly receive a vast amount of information, and our brain continuously sorts through this storm of sensory stimuli â be it to appreciate a painting, hear a warning shout, navigate a room, or shape a pot of clay. This is most readily apparent in our sense of vision. Only a very small area of our field of view is actually perceived clearly and in focus. As a result, fast movements of the eye muscles â movements known as saccades â periodically direct the angle of viewing to any points that seem interesting. The brain puts these points together and constructs an unbroken image. Saccades take place 3-5 times per second â much faster than our heart beats. For example, when we look at a face, our gaze quickly dances across the eyes, nose, mouth, chin, and forehead, to provide the pieces from which the whole face is assembled in our mind.
However, there are times in which we focus on a single spot, for example when threading a needle. This requires tremendous focus of the eyes on the âeyeâ of the needle. But even during intense concentration on such a small point in space, the brain still keeps up awareness of the periphery, so we can react to anything happening in our broader field of view. TĂŒbingen investigators led by Dr. Ziad Hafed (CIN) have now analyzed data collected in collaboration with the team of Prof. Dr. Peter Thier (HIH) to uncover how this peripheral awareness functions: rather than completely eliminating all eye movements while focusing on the needle, the brain instead makes use of tiny, almost imperceptible eye movements â mere fractions of a degree in size. Hafed and his team found that these tiny eye movements play a major role in âhighlightingâ sensory information in our periphery â without us even being aware of them.
These very small eye movements are called microsaccades. In contrast to normal saccades, which let us look at a new object or part of it in our field of view, microsaccades only result in what seem at first glance to be negligible readjustments. However, in their investigation, Dr. Hafed and his team were able to detect an increase in neuronal activity immediately before the occurrence of each microsaccade â evidence of heightened attention and a highlighting of the visual scene. Microsaccades follow a recognizable, quick rhythm, undulating several times per second. Even points far away from the eyeâs focus are âhighlightedâ when microsaccades increase attention. This mechanism allows our brain to âkeep an eye outâ even when our eyes are busy, keeping tabs on the environment, warning of danger, and thus allowing our active perception to rapidly re-focus on anything that might happen.
Hafed and his teamâs results potentially open the door to future engineering applications. For example, if computer interfaces were to track computer usersâ microsaccades with cameras, computers could predict when the usersâ brains may be more or less sensitized to new stimuli. Such âsmartâ user interfaces could thus optimize on a millisecond basis when and where to provide visual feedback to their users to maximize work efficiency.
How Neurons Remember
Scientists at CharitĂ© â UniversitĂ€tsmedizin Berlin have identified a mechanism at the level of the individual neurons (nerve cells) that may play a role in the formation of memory. They have determined that back-propagating electrical impulses serve to activate a receptor inside the cell, thereby resulting in long-term changes in the calcium response in specific neuronal compartments. The results of their study have now been published in the scientific journal PloS Biology.
Research findings obtained over the past decades increasingly indicate that stored memories are coded as permanent changes of neuronal communication and the strength of neuronal interconnections. The learning process evokes a specific pattern of electrical activity in these cells, which influences the response behavior to incoming signals, the expression of genes and the cellular morphology beyond the learning process itself.
âYou might say that these changes define the cellular correlate of the memory engramâ says Friedrich Johenning, researcher at the Neuroscience Research Center and one of the studyâs two co-lead authors. âOur work focuses on identifying physiological mechanisms through which a neuron can implement long-term changes of its responseâ, adds the other co-lead author Anne-Kathrin Theis.
In their study the scientists succeeded in demonstrating that the spine calcium response to action potentials back-propagating into the dendritic tree can undergo long-term enhancement. Spines are small but important dendritic processes that facilitate communication between neurons. Whenever a back-propagating action potential encounters such a spine, the calcium concentration within the spines changes due to the rapid influx of calcium ions from the outside via ion channels on the plasma membrane. In addition, the intracellular ryanodine receptor gets activated, which triggers the release of calcium stored in the cell. This store release results in a long-term modification of the calcium response elicited by electrical impulses inside the spine. It should be noted that these changes are local in nature and limited to individual spines â the neighboring processes remain unaffected.
âThe challenge is to now ascertain exactly what influence these spine-specific, long-term, altered calcium responses exert on the synaptic communication between the neurons. It is also important for us to establish a relationship to pathological calcium response changes occurring in the context of neuropsychiatric diseases â, according to Dietmar Schmitz, senior author and head of the study.