Chapter 3. Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
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Thorsten Rudroff An estimated 400,000 Americans are currently living with multiple sclerosis, an autoimmune disease where the body’s immune cells attack a fatty substance called myelin in the nerves. Common symptoms are gait and balance disorders, cognitive dysfunction, fatigue, pain and muscle spasticity. Colorado has the highest proportion of people living with MS in the United States. It is estimated that one in 550 people living in the state has MS, compared to one in 750 nationally. The reason for this is unknown, but could be related to several factors, such as vitamin D deficiency or environment. Currently available therapies do not sufficiently relieve MS symptoms. As a result many people with the condition are trying alternative therapies, like cannabis. Based on several studies, the American Association of Neurology states that there is strong evidence that cannabis is effective for treatment of pain and spasticity. Although there are many anecdotal reports indicating cannabis’ beneficial effects for treatment of MS symptoms such as fatigue, muscle weakness, anxiety and sleep deprivation, they have not been scientifically verified. This is because clinical trials – where patients are given cannabis – are difficult to do because of how the substance is regulated at the federal level. To learn more, my Integrative Neurophysiology Laboratory at Colorado State University is studying people with MS in the state who are already using medical cannabis as a treatment to investigate what MS symptoms the drug can effectively treat. © 2010–2017, The Conversation US, Inc.
Riley Beggin Matt Herich uses a tDCS device that was made by another student he met on Reddit. Four 9-volt batteries and sticky self-adhesive electrodes are connected by a circuit board that sends a constant small current to the user's brain. Courtesy of Matt Herich Last October, Matt Herich was listening to the news while he drove door to door delivering pizzas. A story came on the radio about a technology that sends an electric current through your brain to possibly make you better at some things — moving, remembering, learning. He was fascinated. The neurotechnology is called transcranial direct current stimulation, or tDCS for short. At its simplest, the method involves a device that uses little more than a 9-volt battery and some electrodes to send a low-intensity electrical current to a targeted area of the brain, typically via a headset. More than a 1,000 studies have been published in peer-reviewed journals over the last decade suggesting benefits of the technique — maybe regulating mood, possibly improving language skills — but its effects, good or bad, are far from clear. Although researchers see possibilities for tDCS in treating diseases and boosting performance, it's still an exploratory technology, says Mark George, editor-in-chief of Brain Stimulation, a leading journal on neuromodulation. And leading experts have warned against at-home use of such devices. © 2017 npr
Keyword: Learning & Memory
Link ID: 23071 - Posted: 01.09.2017
Brandie Jefferson When I told my coworker that I was participating in a study that involved fasting, she laughed until she nearly cried. My boyfriend, ever supportive, asked hesitantly, "Are you sure you want to try this?" Note the use of "try" instead of "do." When I told my father over the phone, the line went silent for a moment. Then he let out a long, "Welllllll," wished me luck, and chuckled. Turns out, luck might not be enough. I like to eat. Often and a lot. Now, however, my eating habits have become more than a source of amusement for friends and coworkers. Now they are data in a study focusing on people with multiple sclerosis, like me. The pilot study, led by Dr. Ellen Mowry at the Johns Hopkins University in Baltimore, is looking at the impact of intermittent fasting on our microbiomes — the universe of trillions of microbes, mainly bacteria, that live in our guts. Intermittent fasting is pretty much what it sounds like. For six months, participants are allowed to eat during an 8-hour period each day. The remaining 16 hours we are limited to water, tea and coffee. No added sugar, cream, honey or sweetener. Several studies have suggested that the predominant bacteria in the guts of people with MS tend to be different than those in the guts of those without the chronic autoimmune inflammatory disease, according to Samantha Roman, the study's research coordinator. Depending on their makeup, bacteria have the ability to soothe or trigger inflammation, potentially affecting the symptoms of MS and other diseases. Exactly how gut bacteria and inflammation are related, though, is not well understood. © 2017 npr
Keyword: Multiple Sclerosis
Link ID: 23070 - Posted: 01.09.2017
By Jessica Hamzelou One woman’s unique experiences are helping us understand the nature of synaesthesia. We don’t know yet what causes synaesthesia, which links senses and can enable people to taste words or smell sounds, for example. It may be at least partly genetic, as it tends to run in families. Some researchers think a brain chemical called serotonin might play a role, because hallucinogenic drugs that alter serotonin levels in the brain can create unusual perceptions. There’s also some evidence that synaesthesia can change or disappear, and a detailed assessment of one woman’s experiences is helping Kevin Mitchell at Trinity College Dublin in Ireland and his team investigate. The woman, referred to as “AB”, sees colours when she hears music, linked to pitch, volume or instrument – higher notes have more pastel shades. She also associates colours with people, largely based on personality. Green is linked to loyalty, for instance. But several experiences in her life have caused her synaesthesia to change. “To say she had a series of unfortunate events would be an understatement,” says Mitchell. As a teenager and young adult, AB sustained several concussions, had migraines, contracted viral meningitis and was struck by lightning. © Copyright Reed Business Information Ltd.
Link ID: 23054 - Posted: 01.04.2017
By KATHARINE Q. SEELYE BROOKLINE, Mass. — When Michael Dukakis lost the presidential election in 1988, his wife, Kitty, felt as if she had been squashed in a compactor, all the air forced out of her. Her even-keeled husband went back to work as governor of Massachusetts; she started binge drinking. “An alcoholic can contain himself for only so long,” Mrs. Dukakis would later write. “When a crisis hits, the restraints snap.” Her drinking masked a long-smoldering depression that eventually led her to receive electroconvulsive therapy, also known as electroshock therapy or ECT. Like most people, she had no idea that the procedure was still used. She thought it a relic, scrapped after it was depicted as an instrument of torture in the 1975 movie “One Flew Over the Cuckoo’s Nest.” But Mrs. Dukakis was desperate. Rehabilitation, talk therapy and antidepressants had failed to ease her crippling depression, so in 2001, at age 64, she turned to shock therapy. To her amazement, it helped. After the first treatment, Mrs. Dukakis wrote, “I felt alive,” as if a cloud had lifted — so much so that when Mr. Dukakis picked her up at Massachusetts General Hospital, she astonished him by proposing that they go out to dinner. “I was so shocked I almost drove off Storrow Drive,” Mr. Dukakis recalled. “I had left this wife of mine at the hospital a basket case just the night before.” Now, 15 years later, the Dukakises have emerged as the nation’s most prominent evangelists for electroconvulsive therapy. Truth be told, there is not much competition. Few boldface names who have had the treatment will acknowledge as much; the stigma is still too great. Exceptions include Carrie Fisher, the actress and writer who died Tuesday, and Dick Cavett, the talk-show host; both have openly discussed their positive experiences. Electroconvulsive therapy is not a one-and-done procedure. Mrs. Dukakis, 80, still receives maintenance treatment every seven or eight weeks. She said that she had minor memory lapses but that the treatment had banished her demons and that she no longer drank, smoked or took antidepressants. © 2017 The New York Times Company
Link ID: 23047 - Posted: 01.02.2017
By James Gallagher Health and science reporter, BBC News website A drug that alters the immune system has been described as "big news" and a "landmark" in treating multiple sclerosis, doctors and charities say. Trials, published in the New England Journal of Medicine, suggest the drug can slow damage to the brain in two forms of MS. Ocrelizumab is the first drug shown to work in the primary progressive form of the disease. The drug is being reviewed for use in the US and Europe. MS is caused by a rogue immune system mistaking part of the brain for a hostile invader and attacking it. It destroys the protective coating that wraps round nerves called the myelin sheath. The sheath also acts like wire insulation to help electrical signals travel down the nerve. Damage to the sheath prevents nerves from working correctly and means messages struggle to get from the brain to the body. This leads to symptoms like having difficulty walking, fatigue and blurred vision. The disease can either just get worse, known as primary progressive MS, or come in waves of disease and recovery, known as relapsing remitting MS. Both are incurable, although there are treatments for the second state. 'Change treatment' Ocrelizumab kills a part of the immune system - called B cells - which are involved in the assault on the myelin sheath. In 732 patients with progressive MS, the percentage of patients that had deteriorated fell from 39% without treatment to 33% with ocrelizumab . Patients taking the drug also scored better on the time needed to walk 25 feet and had less brain loss detected on scans. In 1,656 patients with relapsing remitting, the relapse rate with ocrelizumab was half that of using another drug. © 2016 BBC
Laura Sanders Flickering light kicks off brain waves that clean a protein related to Alzheimer’s disease out of mice’s brains, a new study shows. The results, described online December 7 in Nature, suggest a fundamentally new approach to counteracting Alzheimer’s. Many potential therapies involve drugs that target amyloid-beta, the sticky protein that accumulates in the brains of Alzheimer’s patients. In contrast, the new method used on mice causes certain nerve cells to fire at a specific rhythm, generating brain waves that researchers believe may clear A-beta. “This is a very creative and innovative new approach to targeting brain amyloid load in Alzheimer’s,” says geriatric psychiatrist Paul Rosenberg of Johns Hopkins Medicine. But he cautions that the mouse results are preliminary. Neuroscientist Li-Huei Tsai of MIT and colleagues saw that mice engineered to produce lots of A-beta don’t produce as many gamma waves in the hippocampus, a brain structure important for memory. Using a method called optogenetics, the researchers genetically designed certain nerve cells in the hippocampus to fire off signals in response to light. In this way, the researchers induced gamma waves — rhythmic firings 40 times per second. After just an hour of forced gamma waves, the mice had less A-beta in the hippocampus, the researchers found. Further experiments revealed that gamma waves packed a double whammy — they lowered A-beta by both reducing production and enhancing the brain’s ability to clear it. © Society for Science & the Public 2000 - 2016
Link ID: 22966 - Posted: 12.08.2016
Sara Reardon A new technique might allow researchers and clinicians to stimulate deep regions of the brain, such as those involved in memory and emotion, without opening up a patient’s skull. Brain-stimulation techniques that apply electrodes to a person’s scalp seem to be safe, and proponents say that the method can improve some brain functions, including enhancing intelligence and relieving depression. Some of these claims are much better supported by research than others. But such techniques are limited because they cannot reach deep regions of the brain. By contrast, implants used in deep brain stimulation (DBS) are much more successful at altering the inner brain. The devices can be risky, however, because they involve surgery, and the implants cannot be repaired easily if they malfunction. At the annual Society for Neuroscience conference, held in San Diego, California, last week, neuroengineer Nir Grossman of the Massachusetts Institute of Technology in Cambridge and his colleagues presented their experimental method that adapts transcranial stimulation (TCS) for the deep brain. Their approach involves sending electrical signals through the brain from electrodes placed on the scalp and manipulating the electrical currents in a way that negates the need for surgery. The team used a stimulation device to apply two electric currents to the mouse's skull behind its ears and tuned them to slightly different high frequencies. They angled these two independent currents so that they intersected with each other at the hippocampus. © 2016 Macmillan Publishers Limited,
By Clare Wilson It’s one of the boldest treatments in medicine: delivering an electrical current deep into the brain by implanting a long thin electrode through a hole in the skull. Such “deep brain stimulation” (DBS) works miracles on people with otherwise untreatable epilepsy or Parkinson’s disease – but drilling into someone’s head is an extreme step. In future, we may be able to get the same effects by using stimulators placed outside the head, an advance that could see DBS used to treat a much wider range of conditions. DBS is being investigated for depression, obesity and obsessive compulsive disorder, but this research is going slowly. Implanting an electrode requires brain surgery, and carries a risk of infection, so the approach is only considered for severe cases. But Nir Grossman of Imperial College London and his team have found a safer way to experiment with DBS – by stimulating the brain externally, with no need for surgery. The technique, unveiled at the Society for Neuroscience conference in San Diego, California, this week, places two electrical fields of different frequencies outside the head. The brain tissue where the fields overlap is stimulated, while the tissue under just one field is unaffected because the frequencies are too high. For instance, they may use one field at 10,000 hertz and another at 10,010 hertz. The affected nerve cells are stimulated at 10 hertz – the difference between the two frequencies. © Copyright Reed Business Information Ltd.
Link ID: 22875 - Posted: 11.16.2016
By Alison F. Takemura In the mid-1980s, György Buzsáki was trying to get inside rats’ heads. Working at the University of California, San Diego, he would anesthetize each animal with ether and hypothermia, cut through its scalp, and drill holes in its skull. Carefully, he’d screw 16 gold-plated stainless steel electrodes into the rat’s brain. When he was done with the surgery, these tiny pieces of metal—just 0.5 mm in diameter—allowed him to measure voltage changes from individual neurons deep in the brain’s folds, all while the rodent was awake and moving around. He could listen to the cells fire action potentials as the animal explored its environment, learning and remembering what it encountered (J Neurosci, 8:4007-26, 1988). In those days, recording from two cells simultaneously was the norm. The 16-site recording in Buzsáki’s 1988 study “was the largest ever in a rat,” he says. Nowadays, scientists can measure voltage changes from 1,000 neurons at the same time with silicon multielectrode arrays. But the basic techniques of using a probe to measure electrical activity within the brain (electrophysiology) or from outside it (electroencephalography, or EEG) are still workhorses of neural imaging labs. “The new tools don’t replace the old ones,” says Jessica Cardin, a neuroscientist at the Yale School of Medicine. “They add new layers of information.” Another decades-old neuroscientific technique that remains popular today is patch clamping. Developed in the late 1970s and early 1980s, it can detect changes in the electric potential of individual cells, or even single ion channels. With a tiny glass pipette suctioned against the cell’s membrane, researchers can make a small tear, sealed by the pipette tip, and detect voltage changes inside the cell. With some improvements, the patch clamp, like electrophysiology and EEG, has remained a regular part of the neuroscientist’s tool kit. Recently, researchers had a robot carry out the process (Nat Methods, 9:585-87, 2012). © 1986-2016 The Scientist
Keyword: Brain imaging
Link ID: 22783 - Posted: 10.25.2016
By Gary Stix The new mantra for researchers fighting Alzheimer’s disease is “go early,” before memory loss or other pathology appears. The rationale for this approach holds that by the time dementia sets in the disease may already be destroying brain cells, placing severe limits on treatment options. Some large clinical trials are now testing drugs intended to clear up the brain’s cellular detritus—the aggregations of amyloid and tau proteins that may ultimately destroy brain cells. So far this approach has had decidedly mixed results. Some researchers are choosing a different direction. They have begun to ask what happens in the brain before the plaques and tangles of amyloid and tau appear—and to look at interventions that might work at this incipient disease stage. The Alzheimer’s Disease Drug Discovery Foundation has focused in recent years on funding new agents that do not target amyloid but are intended to address other manifestations of the disease, such as inflammation and the energy metabolism of neurons. At a meeting last month in Jersey City, N.J., neuroscientist Grace Stutzmann of the Chicago Medical School at Rosalind Franklin University of Medicine and Science presented her work on restoring a basic cellular process—called calcium signaling—that goes off track in Alzheimer’s. Scientific American asked her recently about her work. © 2016 Scientific American,
Link ID: 22754 - Posted: 10.13.2016
ByAnna Vlasits The next revolution in medicine just might come from a new lab technique that makes neurons sensitive to light. The technique, called optogenetics, is one of the biggest breakthroughs in neuroscience in decades. It has the potential to cure blindness, treat Parkinson’s disease, and relieve chronic pain. Moreover, it’s become widely used to probe the workings of animals’ brains in the lab, leading to breakthroughs in scientists’ understanding of things like sleep, addiction, and sensation. So it’s not surprising that the two Americans hailed as inventors of optogenetics are rock stars in the science world. Karl Deisseroth at Stanford University and Ed Boyden at the Massachusetts Institute of Technology have collected tens of millions in grants and won millions in prize money in recent years. They’ve stocked their labs with the best equipment and the brightest minds. They’ve been lauded in the media and celebrated at conferences around the world. They’re considered all but certain to win a Nobel Prize. There’s only one problem with this story: It just may be that Zhuo-Hua Pan invented optogenetics first. Even many neuroscientists have never heard of Pan. Pan, 60, is a vision scientist at Wayne State University in Detroit who began his research career in his home country of China. He moved to the United States in the 1980s to pursue his PhD and never left. He wears wire-rimmed glasses over a broad nose framed by smile-lines in his cheeks. His colleagues describe him as a pure scientist: modest, dedicated, careful.
Keyword: Brain imaging
Link ID: 22625 - Posted: 09.03.2016
By GINA KOLATA Shena Pearson nearly froze in her seat, terrified, as she stared at a power-point slide. She was at her first meeting of an epilepsy foundation, seeking help for her 12-year-old son Trysten, when a neurologist flashed the slide about something called Sudep. It stands for sudden unexpected death in epilepsy. Her son’s neurologist had never mentioned it. “Oh dear God, my child is at risk, seriously at risk,” Ms. Pearson thought to herself. Sudden death in epilepsy is a little-known and seldom-mentioned phenomenon, but now, after a push by advocates, the federal government has begun a concerted program to understand it. Yet a question remains: When, if ever, should patients be warned? In a way, the extreme reticence of many neurologists to mention sudden unexpected death to epilepsy patients harks back to the days when doctors and families often did not tell people they had cancer — too terrifying. But today, patients learn not just about cancer but about many other potentially fatal conditions, like an inoperable brain aneurysm that could burst at any time and kill a person. So the quiet about the epilepsy death risk appears to be an anomaly. Sudep’s name pretty much explains what it is: Someone with epilepsy — unprovoked seizures, which are electrical surges in the brain — dies, and there is no apparent cause. Often a person with epilepsy goes to bed and is found in the morning, unresponsive. In some cases, there is indirect evidence of a seizure, like urine on the sheets, bloodshot eyes or a severely bitten tongue, leading to the suggestion that preventing seizures as much as possible with medications could lower patients’ risks. But so much about the syndrome remains unknown. © 2016 The New York Times Company
Link ID: 22587 - Posted: 08.23.2016
SINCE nobody really knows how brains work, those researching them must often resort to analogies. A common one is that a brain is a sort of squishy, imprecise, biological version of a digital computer. But analogies work both ways, and computer scientists have a long history of trying to improve their creations by taking ideas from biology. The trendy and rapidly developing branch of artificial intelligence known as “deep learning”, for instance, takes much of its inspiration from the way biological brains are put together. The general idea of building computers to resemble brains is called neuromorphic computing, a term coined by Carver Mead, a pioneering computer scientist, in the late 1980s. There are many attractions. Brains may be slow and error-prone, but they are also robust, adaptable and frugal. They excel at processing the sort of noisy, uncertain data that are common in the real world but which tend to give conventional electronic computers, with their prescriptive arithmetical approach, indigestion. The latest development in this area came on August 3rd, when a group of researchers led by Evangelos Eleftheriou at IBM’s research laboratory in Zurich announced, in a paper published in Nature Nanotechnology, that they had built a working, artificial version of a neuron. Neurons are the spindly, highly interconnected cells that do most of the heavy lifting in real brains. The idea of making artificial versions of them is not new. Dr Mead himself has experimented with using specially tuned transistors, the tiny electronic switches that form the basis of computers, to mimic some of their behaviour. © The Economist Newspaper Limited 2016.
By Simon Makin A technology with the potential to blur the boundaries between biology and electronics has just leaped a major hurdle in the race to demonstrate its feasibility. A team at the University of California, Berkeley, led by neuroscientist Jose Carmena and electrical and computer engineer Michel Maharbiz, has provided the first demonstration of what the researchers call “ultrasonic neural dust” to monitor neural activity in a live animal. They recorded activity in the sciatic nerve and a leg muscle of an anesthetized rat in response to electrical stimulation applied to its foot. “My lab has always worked on the boundary between biology and man-made things,” Maharbiz says. “We build tiny gadgets to interface synthetic stuff with biological stuff.” The work was published last week in the journal Neuron. The system uses ultrasound for both wireless communication and the device’s power source, eliminating both wires and batteries. It consists of an external transceiver and what the team calls a “dust mote” about 0.8x1x3 mm size, which is implanted inside the body. The transceiver sends ultrasonic pulses to a piezoelectric crystal in the implant, which converts them into electricity to provide power. The implant records electrical signals in the rat via electrodes, and uses this signal to alter the vibration of the crystal. These vibrations are reflected back to the transceiver, allowing the signal to be recorded—a technique known as backscatter. “This is the first time someone has used ultrasound as a method of powering and communicating with extremely small implantable systems,” says one of the paper’s authors, Dongjin Seo. “This opens up a host of applications in terms of embodied telemetry: being able to put something super-tiny, super-deep in the body, which you can park next to a nerve, organ, muscle or gastrointestinal tract, and read data out wirelessly.” © 2016 Scientific American
Keyword: Brain imaging
Link ID: 22533 - Posted: 08.09.2016
By James Gallagher Controlling human nerve cells with electricity could treat a range of diseases including arthritis, asthma and diabetes, a new company says. Galvani Bioelectronics hopes to bring a new treatment based on the technique before regulators within seven years. GlaxoSmithKline and Verily, formerly Google, Life Sciences, are behind it. Animal experiments have attached tiny silicone cuffs, containing electrodes, around a nerve and then used a power supply to control the nerve's messages. One set of tests suggested the approach could help treat type-2 diabetes, in which the body ignores the hormone insulin. They focused on a cluster of chemical sensors near the main artery in the neck that check levels of sugar and the hormone insulin. The sensors send their findings back to the brain, via a nerve, so the organ can coordinate the body's response to sugar in the bloodstream. GSK vice-president of bioelectronics Kris Famm told the BBC News website: "The neural signatures in the nerve increase in type 2-diabetes. "By blocking those neural signals in diabetic rats, you see the sensitivity of the body to insulin is restored." And early work suggested it could work in other diseases too. "It isn't just a one-trick-pony, it is something that if we get it right could have a new class of therapies on our hands," Mr Famm said. But he said the field was only "scratching the surface" when it came to understanding which nerve signals have what effect in the body. Both the volume and rhythm of the nerve signals could be having an effect rather than it being a simple case of turning the nerve on or off. © 2016 BBC
Link ID: 22507 - Posted: 08.03.2016
By Jessica Boddy Ever wonder what it looks like when brain cells chat up a storm? Researchers have found a way to watch the conversation in action without ever cracking open a skull. This glimpse into the brain’s communication system could open new doors to diagnosing and treating disorders from epilepsy to Alzheimer’s disease. Being able to see where—and how—living brain cells are working is “the holy grail in neuroscience,” says Howard Federoff, a neurologist at Georgetown University in Washington, D.C., who was not involved with the work. “This is a possible new tool that could bring us closer to that.” Neurons, which are only slightly longer than the width of a human hair, are laid out in the brain like a series of tangled highways. Signals must travel down these highways, but there’s a catch: The cells don’t actually touch. They’re separated by tiny gaps called synapses, where messages, with the assistance of electricity, jump from neuron to neuron to reach their destinations. The number of functional synapses that fire in one area—a measure known as synaptic density—tends to be a good way to figure out how healthy the brain is. Higher synaptic density means more signals are being sent successfully. If there are significant interruptions in large sections of the neuron highway, many signals may never reach their destinations, leading to disorders like Huntington disease. The only way to look at synaptic density in the brain, however, is to biopsy nonliving brain tissue. That means there’s no way for researchers to investigate how diseases like Alzheimer’s progress—something that could hold secrets to diagnosis and treatment. © 2016 American Association for the Advancement of Science
Keyword: Brain imaging
Link ID: 22472 - Posted: 07.23.2016
By ANNA WEXLER EARLIER this month, in the journal Annals of Neurology, four neuroscientists published an open letter to practitioners of do-it-yourself brain stimulation. These are people who stimulate their own brains with low levels of electricity, largely for purposes like improved memory or learning ability. The letter, which was signed by 39 other researchers, outlined what is known and unknown about the safety of such noninvasive brain stimulation, and asked users to give careful consideration to the risks. For the last three years, I have been studying D.I.Y. brain stimulators. Their conflict with neuroscientists offers a fascinating case study of what happens when experimental tools normally kept behind the closed doors of academia — in this case, transcranial direct current stimulation — are appropriated for use outside them. Neuroscientists began experimenting in earnest with transcranial direct current stimulation about 15 years ago. In such stimulation, electric current is administered at levels that are hundreds of times less than those used in electroconvulsive therapy. To date, more than 1,000 peer-reviewed studies of the technique have been published. Studies have suggested, among other things, that the stimulation may be beneficial for treating problems like depression and chronic pain as well as enhancing cognition and learning in healthy individuals. The device scientists use for stimulation is essentially a nine-volt battery attached to two wires that are connected to electrodes placed at various spots on the head. A crude version can be constructed with just a bit of electrical know-how. Consequently, as reports of the effects of the technique began to appear in scientific journals and in newspapers, people began to build their own devices at home. By late 2011 and early 2012, diagrams, schematics and videos began to appear online. © 2016 The New York Times Company
Link ID: 22471 - Posted: 07.23.2016
By Emma Bryce In 1999, neuroscientist Gero Miesenböck dreamed of using light to expose the brain's inner workings. Two years later, he invented optogenetics, a technique that fulfils this goal: by genetically engineering cells to contain proteins that make them light-responsive, Miesenböck found he could shine light at the brain and trigger electrical activity in those cells. This technique gave scientists the tools to activate and control specific cell populations in the brain, for the first time. For example, Miesenböck, who directs the Centre for Neural Circuits and Behaviour at the University of Oxford, first used optogenetics to activate courtship responses in fruit flies, and even make headless flies take flight - groundbreaking experiments that allowed him to examine, in unprecedented detail, how neurons drive behaviour. Gero Miesenböck: There was almost a "eureka" moment. As is often the case, you tend to have your best ideas when you're not trying to have them: suddenly I had this idea - which I must have been incubating for a long time, because I was thinking about manipulating neurons in the brain genetically to emit light so I could visualise their activity. Suddenly I thought, "What if we just turn the thing upside down, and instead of reading activity, write activity using light and genetics?" That was the real breakthrough idea, and then of course came the big challenge of having to make it work. Brains are composed of many different kinds of nerve cells, and they are genetically distinct from one another. To deconstruct how the brain works we need to pinpoint the roles these individual classes of cells play in processing information. Optogenetics uses the genetic signatures that define individual cell types to address them selectively in the intact brain - that's the "genetics" component. The "opto" component is to use these genetic signatures to place light-sensitive molecules that are encoded in DNA within these cells.
Link ID: 22469 - Posted: 07.23.2016
By Minaz Kerawala, For years, gamers, athletes and even regular people trying to improving their memory have resorted, with electrified enthusiasm, to "brain zapping" to gain an edge. The procedure, called transcranial direct current stimulation (tDCS), uses a battery and electrodes to deliver electrical pulses to the brain, usually through a cap or headset fitted close to the scalp. Proponents say these currents are beneficial for a range of neurological conditions like Alzheimer's and Parkinson's diseases, stroke and schizophrenia, but experts are warning that too little is known about the safety of tDCS. "You might end up with a placement of electrodes that doesn't do what you think it does and could potentially have long-lasting effects," said Matthew Krause, a neuroscientist at the Montreal Neurological Institute. All functions of the brain—thought, emotion and coordination—are carried out by neurons using pulses of electricity. "The objective of all neuroscience is to influence these electrical processes," Krause said. The brain's activity can be influenced by drugs that alter its electrochemistry or by external external electric fields. While mind-altering headsets may seem futuristic, tDCS is not a new procedure. Much of the pioneering work in the field was done in Montreal by Dr. Wilder Penfield in the 1920s and 30s. ©2016 CBC/Radio-Canada.
Link ID: 22464 - Posted: 07.21.2016