Chapter 2. Functional Neuroanatomy: The Nervous System and Behavior
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Mo Costandi A team of neuroscientists at University College London has developed a new way of simultaneously recording and manipulating the activity of multiple cells in the brains of live animals using pulses of light. The technique, described today in the journal Nature Methods, combines two existing state-of-the-art neurotechnologies. It may eventually allow researchers to do away with the cumbersome microelectrodes they traditionally used to probe neuronal activity, and to interrogate the brain’s workings at the cellular level in real time and with unprecedented detail. One of them is optogenetics. This involves creating genetically engineered mice expressing algal proteins called Channelrhodopsins in specified groups of neurons. This renders the cells sensitive to light, allowing researchers to switch the cells on or off, depending on which Channelrhodopsin protein they express, and which wavelength of light is used. This can be done on a millisecond-by-millisecond timescale, using pulses of laser light delivered into the animals’ brains via an optical fibre. The other is calcium imaging. Calcium signals are crucial for just about every aspect of neuronal function, and nerve cells exhibit a sudden increase in calcium ion concentration when they begin to fire off nervous impulses. Using dyes that give off green fluorescence in response to increases in calcium concentration, combined with two-photon microscopy, researchers can detect this signature to see which cells are activated. In this way, they can effectively ‘read’ the activity of entire cell populations in brain tissue slices or live brains. Calcium-sensitive dyes are injectable, so targeting them with precision is difficult, and more recently, researchers have developed genetically-encoded calcium sensors to overcome this limitation. Mice can be genetically engineered to express these calcium-sensitive proteins in specific groups of cells; like the dyes before them, they, too, fluoresce in response to increases in calcium ion concentrations in the cells expressing them.
Keyword: Brain imaging
Link ID: 20441 - Posted: 12.23.2014
by Helen Thomson Zapping your brain might make you better at maths tests – or worse. It depends how anxious you are about taking the test in the first place. A recent surge of studies has shown that brain stimulation can make people more creative and better at maths, and can even improve memory, but these studies tend to neglect individual differences. Now, Roi Cohen Kadosh at the University of Oxford and his colleagues have shown that brain stimulation can have completely opposite effects depending on your personality. Previous research has shown that a type of non-invasive brain stimulation called transcranial direct current stimulation (tDCS) – which enhances brain activity using an electric current – can improve mathematical ability when applied to the dorsolateral prefrontal cortex, an area involved in regulating emotion. To test whether personality traits might affect this result, Kadosh's team tried the technique on 25 people who find mental arithmetic highly stressful, and 20 people who do not. They found that participants with high maths anxiety made correct responses more quickly and, after the test, showed lower levels of cortisol, an indicator of stress. On the other hand, individuals with low maths anxiety performed worse after tDCS. "It is hard to believe that all people would benefit similarly [from] brain stimulation," says Cohen Kadosh. He says that further research could shed light on how to optimise the technology and help to discover who is most likely to benefit from stimulation. © Copyright Reed Business Information Ltd.
Ian Sample, science editor Electrical brain stimulation equipment – which can boost cognitive performance and is easy to buy online – can have bad effects, impairing brain functioning, research from scientists at Oxford University has shown. A steady stream of reports of stimulators being able to boost brain performance, coupled with the simplicity of the devices, has led to a rise in DIY enthusiasts who cobble the equipment together themselves, or buy it assembled on the web, then zap themselves at home. In science laboratories brain stimulators have long been used to explore cognition. The equipment uses electrodes to pass gentle electric pulses through the brain, to stimulate activity in specific regions of the organ. Roi Cohen Kadosh, who led the study, published in the Journal of Neuroscience, said: “It’s not something people should be doing at home at this stage. I do not recommend people buy this equipment. At the moment it’s not therapy, it’s an experimental tool.” The Oxford scientists used a technique called transcranial direct current stimulation (tDCS) to stimulate the dorsolateral prefrontal cortex in students as they did simple sums. The results of the test were surprising. Students who became anxious when confronted with sums became calmer and solved the problems faster than when they had sham stimulation (the stimulation itself lasted only 30 seconds of the half hour study). The shock was that the students who did not fear maths performed worse with the same stimulation.
| By Carolyn Gregoire When reading about Harry Potter's adventures fighting Lord Voldemort or flying around the Quidditch field on his broomstick, we can become so absorbed in the story that the characters and events start to feel real. And according to neuroscientists, there's a good reason for this. Researchers in the Machine Learning Department at Carnegie Mellon University scanned the brains of Harry Potter readers, and found that reading about Harry's adventures activates the same brain regions used to perceive people's intentions and actions in the real world. The researchers performed fMRI scans on a group of eight study participants while they read chapter nine of Harry Potter and the Sorcerer's Stone, which describes Harry's first flying lesson. Then, they analyzed the scans, one cubic millimeter at a time, for four-word segments of the chapter in order to build the first integrated computational model of reading. The researchers created a technique such that for each two-second fMRI scan, the readers would see four words. And for each word, the researchers identified 195 detailed features that the brain would process. Then, an algorithm was applied to analyze the activation of each millimeter of the brain for each two-second scan, associating various word features with different regions of the brain. Using the model, the researchers were able to predict which of two passages the subjects were reading with a 74 percent accuracy rate. ©2014 TheHuffingtonPost.com, Inc
|By Ryan Bradley Five years ago Viviana Gradinaru was slicing thin pieces of mouse brain in a neurobiology lab, slowly compiling images of the two-dimensional slivers for a three-dimensional computer rendering. In her spare time, she would go to see the Body Worlds exhibit. She was especially fascinated by the “plasticized” remains of the human circulatory system on display. It struck her that much of what she was doing in the lab could be done more efficiently with a similar process. “Tissue clearing” has been around for more than a century, but existing methods involve soaking tissue samples in solvents, which is slow and usually destroys the fluorescent proteins necessary for marking certain cells of interest. To create a better approach, Gradinaru, at the time a graduate student, and her colleagues in neuroscientist Karl Deisseroth's lab focused on replacing the tissue's lipid molecules, which make it opaque.* To keep the tissue from collapsing, however, the replacement would need to give it structure, as lipids do. The first step was to euthanize a rodent and pump formaldehyde into its body, through its heart. Next they removed the skin and filled its blood vessels with acrylamide monomers, white, odorless, crystalline compounds. The monomers created a supportive hydrogel mesh, replacing the lipids and clearing the tissue. Before long, they could render an entire mouse body transparent in two weeks. Soon they were using transparent mice to map complete mouse nervous systems. The transparency made it possible for them to identify peripheral nerves—tiny bundles of nerves that are poorly understood—and to map the spread of viruses across the mouse's blood-brain barrier, which they did by marking the virus with a fluorescent agent, injecting it into the mouse's tail and watching it spread into the brain. © 2014 Scientific American
Keyword: Brain imaging
Link ID: 20382 - Posted: 12.03.2014
Some teenagers appear to show changes in their brains after one season of playing American football, a small study suggests. Even though players were not concussed during the season, researchers found abnormalities similar to the effects of mild traumatic brain injury. Twenty-four players aged between 16 and 18 were studied and devices on their helmets measured head impacts. The study was presented to the Radiological Society of North America. In recent years, a number of reports have expressed concern about the potential effects on young, developing brains of playing contact sports. These studies have tended to focus on brain changes as a result of concussion. But this study focused on the effects of head impacts on the brain, even when players did not suffer concussion at any point during the season. Using detailed scans of the players' brains before the season began and then again after it ended, the researchers were able to identify slight changes to the white matter of the brain. White matter contains millions of nerve fibres which act as communication cables between the brain's regions. Those players who were hit harder and hit more often were more likely to show these changes in post-season brain scans. Dr Alex Powers, co-author and paediatric neurosurgeon at Wake Forest Baptist Medical Centre in North Carolina, said the changes were a direct result of the hits received by the young players during their football season. BBC © 2014
By David Tuller Patients with chronic fatigue syndrome are accustomed to disappointment. The cause of the disorder remains unknown; it can be difficult to diagnose, and treatment options are few. Research suggesting that an infection from a mouse virus may cause it raised hopes among patients a few years ago, but the evidence fell apart under closer scrutiny. Many patients are still told to seek psychiatric help. But two recent studies — one from investigators at Stanford a few weeks ago and another from a Japanese research team published earlier this year — have found that the brains of people with chronic fatigue syndrome differ from those of healthy people, strengthening the argument that serious physiological dysfunctions are at the root of the condition. “You’ve got two different groups that have independently said, ‘There’s something going on in the brain that is aberrant,’ ” said Leonard Jason, a psychologist at DePaul University in Chicago who studies the condition, also called myalgic encephalomyelitis and widely known as M.E./C.F.S. “I think you have a growing sense that this illness should be taken seriously.” Both studies were small, however, and their results must be replicated before firm conclusions can be drawn. Still, other studies presented at scientific conferences this year also have demonstrated physiological dysfunctions in these patients. In the most recent study, published by the journal Radiology, researchers at Stanford University compared brain images of 15 patients with the condition to those of 14 healthy people. The scientists found differences in both the white matter, the long, cablelike nerve structures that transmit signals between parts of the brain, and the gray matter, the regions where these signals are processed and interpreted. The most striking finding was that in people with the disorder, one neural tract in the white matter of the right hemisphere appeared to be abnormally shaped, as if the cablelike nerve structures had crisscrossed or changed in some other way. Furthermore, the most seriously ill patients exhibited the greatest levels of this abnormality. © 2014 The New York Times Company
by Linda Geddes A tapeworm that usually infects dogs, frogs and cats has made its home inside a man's brain. Sequencing its genome showed that it contains around 10 times more DNA than any other tapeworm sequenced so far, which could explain its ability to invade many different species. When a 50-year-old Chinese man was admitted to a UK hospital complaining of headaches, seizures, an altered sense of smell and memory flashbacks, his doctors were stumped. Tests for tuberculosis, syphilis, HIV and Lyme disease were negative, and although an MRI scan showed an abnormal region in the right side of his brain, a biopsy found inflammation, but no tumour. Over the next four years, further MRIs recorded the abnormal region moving across the man's brain (see animation), until finally his doctors decided to operate. To their immense surprise, they pulled out a 1 centimetre-long ribbon-shaped worm. It looked like a tapeworm, but was unlike any seen before in the UK, so a sample of its tissue was sent to Hayley Bennett and her colleagues at the Wellcome Trust Sanger Institute in Cambridge, UK. Genetic sequencing identified it as Spirometra erinaceieuropaei, a rare species of tapeworm found in China, South Korea, Japan and Thailand. Just 300 human infections have been reported since 1953, and not all of them in the brain. © Copyright Reed Business Information Ltd.
Keyword: Brain imaging
Link ID: 20344 - Posted: 11.21.2014
By Elizabeth Pennisi The microbes that live in your body outnumber your cells 10 to one. Recent studies suggest these tiny organisms help us digest food and maintain our immune system. Now, researchers have discovered yet another way microbes keep us healthy: They are needed for closing the blood-brain barrier, a molecular fence that shuts out pathogens and molecules that could harm the brain. The findings suggest that a woman's diet or exposure to antibiotics during pregnancy may influence the development of this barrier. The work could also lead to a better understanding of multiple sclerosis, in which a leaky blood-brain barrier may set the stage for a decline in brain function. The first evidence that bacteria may help fortify the body’s biological barriers came in 2001. Researchers discovered that microbes in the gut activate genes that code for gap junction proteins, which are critical to building the gut wall. Without these proteins, gut pathogens can enter the bloodstream and cause disease. In the new study, intestinal biologist Sven Pettersson and his postdoc Viorica Braniste of the Karolinska Institute in Stockholm decided to look at the blood-brain barrier, which also has gap junction proteins. They tested how leaky the blood-brain barrier was in developing and adult mice. Some of the rodents were brought up in a sterile environment and thus were germ-free, with no detectable microbes in their bodies. Braniste then injected antibodies—which are too big to get through the blood-brain barrier—into embryos developing within either germ-free moms or moms with the typical microbes, or microbiota. © 2014 American Association for the Advancement of Science
Link ID: 20338 - Posted: 11.20.2014
Sara Reardon A technique that makes mouse brains transparent shows how the entire brain responds to cocaine addiction and fear. The findings could uncover new brain circuits involved in drug response. In the technique, known as CLARITY, brains are infused with acrylamide, which forms a matrix in the cells and preserves their structure along with the DNA and proteins inside them. The organs are then treated with a detergent that dissolves opaque lipids, leaving the cells completely clear. To test whether CLARITY could be used to show how brains react to stimuli, neuroscientists Li Ye and Karl Deisseroth of Stanford University in California engineered mice so that their neurons would make a fluorescent protein when they fired. (The system is activated by the injection of a drug.) The researchers then trained four of these mice to expect a painful foot shock when placed in a particular box; another set of mice placed in the box received cocaine, rather than shocks. Once the mice had learned to associate the box with either pain or an addictive reward, the researchers tested how the animals' brains responded to the stimuli. They injected the mice with the drug that activated the fluorescent protein system, placed them in the box and waited for one hour to give their neurons time to fire. The next step was to remove the animals' brains, treat them with CLARITY, and image them using a system that could count each fluorescent cell across the entire brain (see video). A computer combined these images into a model of a three-dimensional brain, which showed the pathways that lit up when mice were afraid or were anticipating cocaine. © 2014 Nature Publishing Group
Mo Costandi A team of neuroscientists in America say they have rediscovered an important neural pathway that was first described in the late nineteenth century but then mysteriously disappeared from the scientific literature until very recently. In a study published today in Proceedings of the National Academy of Sciences, they confirm that the prominent white matter tract is present in the human brain, and argue that it plays an important and unique role in the processing of visual information. The vertical occipital fasciculus (VOF) is a large flat bundle of nerve fibres that forms long-range connections between sub-regions of the visual system at the back of the brain. It was originally discovered by the German neurologist Carl Wernicke, who had by then published his classic studies of stroke patients with language deficits, and was studying neuroanatomy in Theodor Maynert’s laboratory at the University of Vienna. Wernicke saw the VOF in slices of monkey brain, and included it in his 1881 brain atlas, naming it the senkrechte occipitalbündel, or ‘vertical occipital bundle’. Maynert - himself a pioneering neuroanatomist and psychiatrist, whose other students included Sigmund Freud and Sergei Korsakov - refused to accept Wernicke’s discovery, however. He had already described the brain’s white matter tracts, and had arrived at the general principle that they are oriented horizontally, running mostly from front to back within each hemisphere. But the pathway Wernicke had described ran vertically. Another of Maynert’s students, Heinrich Obersteiner, identified the VOF in the human brain, and mentioned it in his 1888 textbook, calling it the senkrechte occipitalbündel in one illustration, and the fasciculus occipitalis perpendicularis in another. So, too, did Heinrich Sachs, a student of Wernicke’s, who labeled it the stratum profundum convexitatis in his 1892 white matter atlas. © 2014 Guardian News and Media Limited
Link ID: 20333 - Posted: 11.20.2014
By Neuroskeptic An attempt to replicate the results of some recent neuroscience papers that claimed to find correlations between human brain structure and behavior has drawn a blank. The new paper is by University of Amsterdam researchers Wouter Boekel and colleagues and it’s in press now at Cortex. You can download it here from the webpage of one of the authors, Eric-Jan Wagenmakers. Neuroskeptic readers will know Wagenmakers as a critic of statistical fallacies in psychology and a leading advocate of preregistration, which is something I never tire of promoting either. Boekel et al. attempted to replicate five different papers which, together, reported 17 distinct positive results in the form of structural brain-behavior (‘SBB’) correlations. An SBB correlation is an association between the size (usually) of a particular brain area and a particular behavioral trait. For instance, one of the claims was that the amount of grey matter in the amygdala is correlated with the number of Facebook friends you have. To attempt to reproduce these 17 findings, Boekel et al. took 36 students whose brains were scanned with two methods, structural MRI and DWI. The students then completed a set of questionnaires and psychological tests, identical to ones used in the five papers that were up for replication. The methods and statistical analyses were fully preregistered (back in June 2012); Boekel et al. therefore had no scope for ‘fishing’ for positive (or negative) results by tinkering with the methodology. So what did they find? Nothing much. None of the 17 brain-behavior correlations were significant in the replication sample.
Keyword: Brain imaging
Link ID: 20330 - Posted: 11.20.2014
By David Shultz WASHINGTON, D.C.—Reciting the days of the week is a trivial task for most of us, but then, most of us don’t have cooling probes in our brains. Scientists have discovered that by applying a small electrical cooling device to the brain during surgery they could slow down and distort speech patterns in patients. When the probe was activated in some regions of the brain associated with language and talking—like the premotor cortex—the patients’ speech became garbled and distorted, the team reported here yesterday at the Society for Neuroscience’s annual meeting. As scientists moved the probe to other speech regions, such as the pars opercularis, the distortion lessened, but speech patterns slowed. (These zones and their effects are displayed graphically above.) “What emerged was this orderly map,” says team leader Michael Long, a neuroscientist at the New York University School of Medicine in New York City. The results suggest that one region of the brain organizes the rhythm and flow of language while another is responsible for the actual articulation of the words. The team was even able to map which word sounds were most likely to be elongated when the cooling probe was applied. “People preferentially stretched out their vowels,” Long says. “Instead of Tttuesssday, you get Tuuuesdaaay.” The technique is similar to the electrical probe stimulation that researchers have been using to identify the function of various brain regions, but the shocks often trigger epileptic seizures in sensitive patients. Long contends that the cooling probe is completely safe, and that in the future it may help neurosurgeons decide where to cut and where not to cut during surgery. © 2014 American Association for the Advancement of Science.
|By Bret Stetka The brain is protected by formidable defenses. In addition to the skull, the cells that make up the blood-brain barrier keep pathogens and toxic substances from reaching the central nervous system. The protection is a boon, except when we need to deliver drugs to treat illnesses. Now researchers are testing a way to penetrate these bastions: sound waves. Kullervo Hynynen, a medical physicist at Sunnybrook Research Institute in Toronto, and a team of physicians are trying out a technique that involves giving patients a drug followed by an injection of microscopic gas-filled bubbles. Next patients don a cap that directs sound waves to specific brain locations, an approach called high-intensity focused ultrasound. The waves cause the bubbles to vibrate, temporarily forcing apart the cells of the blood-brain barrier and allowing the medication to infiltrate the brain. Hynynen and his colleagues are currently testing whether they can use the method to deliver chemotherapy to patients with brain tumors. They and other groups are planning similar trials for patients with other brain disorders, including Alzheimer's disease. Physicians are also considering high-intensity focused ultrasound as an alternative to brain surgery. Patients with movement disorders such as Parkinson's disease and dystonia are increasingly being treated with implanted electrodes, which can interrupt problematic brain activity. A team at the University of Virginia hopes to use focused ultrasound to deliver thermal lesions deep into the brain without having patients go under the knife. © 2014 Scientific American
By JAMES GORMAN Research on the brain is surging. The United States and the European Union have launched new programs to better understand the brain. Scientists are mapping parts of mouse, fly and human brains at different levels of magnification. Technology for recording brain activity has been improving at a revolutionary pace. The National Institutes of Health, which already spends $4.5 billion a year on brain research, consulted the top neuroscientists in the country to frame its role in an initiative announced by President Obama last year to concentrate on developing a fundamental understanding of the brain. Scientists have puzzled out profoundly important insights about how the brain works, like the way the mammalian brain navigates and remembers places, work that won the 2014 Nobel Prize in Physiology or Medicine for a British-American and two Norwegians. So many large and small questions remain unanswered. How is information encoded and transferred from cell to cell or from network to network of cells? Science found a genetic code but there is no brain-wide neural code; no electrical or chemical alphabet exists that can be recombined to say “red” or “fear” or “wink” or “run.” And no one knows whether information is encoded differently in various parts of the brain. Brain scientists may speculate on a grand scale, but they work on a small scale. Sebastian Seung at Princeton, author of “Connectome: How the Brain’s Wiring Makes Us Who We Are,” speaks in sweeping terms of how identity, personality, memory — all the things that define a human being — grow out of the way brain cells and regions are connected to each other. But in the lab, his most recent work involves the connections and structure of motion-detecting neurons in the retinas of mice. Larry Abbott, 64, a former theoretical physicist who is now co-director, with Kenneth Miller, of the Center for Theoretical Neuroscience at Columbia University, is one of the field’s most prominent theorists, and the person whose name invariably comes up when discussions turn to brain theory. © 2014 The New York Times Company
Keyword: Brain imaging
Link ID: 20302 - Posted: 11.11.2014
Mo Costandi The father of modern neuroscience had a sharp eye and an even sharper mind, but he evidently overlooked something rather significant about the basic structure of brain cells. Santiago Ramón y Cajal spent his entire career examining and comparing nervous tissue from different species. He observed the intricate branches we now call dendrites, and the thicker axonal fibres. He also recognised them as distinct components of the neuron, and convinced others that neurons are fundamental components of the nervous system. For Cajal, these cells were “the mysterious butterflies of the soul… whose beating of wings may one day reveal to us the secrets of the mind.” He hunted for them in “the gardens of the grey matter” and, being an accomplished artist, meticulously catalogued the many “delicate and elaborate forms” that they take. As his beautiful drawings show, all neurons have a single axon emanating from one area of the cell body, and one or more dendrites arising from another. This basic structure has been enshrined in textbooks ever since. But there appear to be unusual varieties of soul butterflies that Cajal failed to spot – neuroscientists in Germany have identified neurons that have axons growing from their dendrites, a discovery that challenges our century-old assumption about the form and function of these cells. Cajal stated that information flows through neurons in only one direction – from the dendrites, which receive electrical impulses from other neurons, to the cell body, which processes the information and conveys it to the initial segment of the axon, which then produces its own impulses that travel down it to the nerve terminal. (He indicated this with small arrows in some of his diagrams, such as the one above.) © 2014 Guardian News and Media Limited
Keyword: Brain imaging
Link ID: 20301 - Posted: 11.11.2014
Sara Reardon Delivering medications to the brain could become easier, thanks to molecules that can escort drugs through the notoriously impervious sheath that separates blood vessels from neurons. In a proof-of-concept study in monkeys, biologists used the system to reduce levels of the protein amyloid-β, which accumulates in the brain plaques associated with Alzheimer's disease1. The blood–brain barrier is a layer of cells lining the inner surface of the capillaries that feed the central nervous system. It is nature's way of protecting the delicate brain from infectious agents and toxic compounds, while letting nutrients and oxygen in and waste products out. Because the barrier strictly regulates the passage of larger molecules and often prevents drug molecules from entering the brain, it has long posed one of the most difficult challenges in developing treatments for brain disorders. Several approaches to bypassing the barrier are being tested, including nanoparticles that are small enough to pass through the barrier's cellular membranes and deliver their payload; catheters that carry a drug directly into the brain; and ultrasound pulses that push microbubbles through the barrier. But no approach has yet found broad therapeutic application. Neurobiologist Ryan Watts and his colleagues at the biotechnology company Genentech in South San Francisco have sought to break through the barrier by exploiting transferrin, a protein that sits on the surface of blood vessels and carries iron into the brain. The team created an antibody with two ends. One end binds loosely to transferrin and uses the protein to transport itself into the brain. And once the antibody is inside, its other end targets an enzyme called β-secretase 1 (BACE1), which produces amyloid-β. Crucially, the antibody binds more tightly to BACE1 than to transferrin, and this pulls it off the blood vessel and into the brain. It locks BACE1 shut and prevents it from making amyloid-β. © 2014 Nature Publishing Group,
Link ID: 20286 - Posted: 11.06.2014
James Gorman Here is something to keep arachnophobes up at night. The inside of a spider is under pressure, like the air in a balloon, because spiders move by pushing fluid through valves. They are hydraulic. This works well for the spiders, but less so for those who want to study what goes on in the brain of a jumping spider, an aristocrat of arachnids that, according to Ronald R. Hoy, a professor of neurobiology and behavior at Cornell University, is one of the smartest of all invertebrates. If you insert an electrode into the spider’s brain, what’s inside might squirt out, and while that is not the kind of thing that most people want to think about, it is something that the researchers at Cornell had to consider. Dr. Hoy and his colleagues wanted to study jumping spiders because they are very different from most of their kind. They do not wait in a sticky web for lunch to fall into a trap. They search out prey, stalk it and pounce. “They’ve essentially become cats,” Dr. Hoy said. And they do all this with a brain the size of a poppy seed and a visual system that is completely different from that of a mammal: two big eyes dedicated to high-resolution vision and six smaller eyes that pick up motion. Dr. Hoy gathered four graduate students in various disciplines to solve the problem of recording activity in a jumping spider’s brain when it spots something interesting — a feat nobody had accomplished before. In the end, they not only managed to record from the brain, but discovered that one neuron seemed to be integrating the information from the spider’s two independent sets of eyes, a computation that might be expected to involve a network of brain cells. © 2014 The New York Times Company
by Helen Thomson As you read this, your neurons are firing – that brain activity can now be decoded to reveal the silent words in your head TALKING to yourself used to be a strictly private pastime. That's no longer the case – researchers have eavesdropped on our internal monologue for the first time. The achievement is a step towards helping people who cannot physically speak communicate with the outside world. "If you're reading text in a newspaper or a book, you hear a voice in your own head," says Brian Pasley at the University of California, Berkeley. "We're trying to decode the brain activity related to that voice to create a medical prosthesis that can allow someone who is paralysed or locked in to speak." When you hear someone speak, sound waves activate sensory neurons in your inner ear. These neurons pass information to areas of the brain where different aspects of the sound are extracted and interpreted as words. In a previous study, Pasley and his colleagues recorded brain activity in people who already had electrodes implanted in their brain to treat epilepsy, while they listened to speech. The team found that certain neurons in the brain's temporal lobe were only active in response to certain aspects of sound, such as a specific frequency. One set of neurons might only react to sound waves that had a frequency of 1000 hertz, for example, while another set only cares about those at 2000 hertz. Armed with this knowledge, the team built an algorithm that could decode the words heard based on neural activity aloneMovie Camera (PLoS Biology, doi.org/fzv269). © Copyright Reed Business Information Ltd.
How Magic Mushrooms Rearrange Your Brain By Brandon Keim A new way of looking at brain activity may give insight into how psychedelic drugs produce their consciousness-altering effects. In recent years, a focus on brain structures and regions has given way to an emphasis on neurological networks: how cells and regions interact, with consciousness shaped not by any given set of brain regions, but by their interplay. Understanding the networks, however, is no easy task, and researchers are developing ever more sophisticated ways of characterizing them. One such approach, described in a new Proceedings of the Royal Society Interface study, involves not simply networks but networks of networks. Perhaps some aspects of consciousness arise from these meta-networks—and to investigate the proposition, the researchers analyzed fMRI scans of 15 people after being injected with psilocybin, the active ingredient in magic mushrooms, and compared them to scans of their brain activity after receiving a placebo. Investigating psychedelia wasn’t the direct purpose of the experiment, said study co-author Giovanni Petri, a mathematician at Italy’s Institute for Scientific Interchange. Rather, psilocybin makes for an ideal test system: It’s a sure-fire way of altering consciousness. “In a normal brain, many things are happening. You don’t know what is going on, or what is responsible for that,” said Petri. “So you try to perturb the state of consciousness a bit, and see what happens.” A representation of that is seen in the image above. Each circle depicts relationships between networks—the dots and colors correspond not to brain regions, but to especially connection-rich networks—with normal-state brains at left, and psilocybin-influenced brains at right. © 2014 Condé Nast.