Links for Keyword: Brain imaging

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Clever math enables MRI to map molecules implicated in multiple sclerosis, other diseases

By Adrian Cho BOSTON—MRI scanners can map a person's innards in exquisite detail, but they say little about composition. Now, physicists are pushing MRI to a new realm of sensitivity to trace specific biomolecules in tissues, a capability that could aid in diagnosing Alzheimer's and other diseases. The advance springs not from improved scanners, but from better methods to solve a notoriously difficult math problem and extract information already latent in MRI data. The new techniques, described this month at a meeting of the American Physical Society here, could soon make the jump to the clinic, says Shannon Kolind, a physicist at the University of British Columbia (UBC) in Vancouver, Canada, who is using them to study multiple sclerosis (MS). "I don't think I'm being too optimistic to say that will happen in the next 5 years," she says. Sean Deoni, a physicist at Brown University, says that "any scanner on the planet can do this." An MRI scanner uses magnetic fields and radio waves to tickle the nuclei of hydrogen atoms—protons—in molecules of water, which makes up more than half of soft tissue. The protons act like little magnets, and the scanner's strong magnetic field makes them all point in one direction. A pulse of radio waves then tips the protons away from the magnetic field, causing them to twirl en masse, like so many gyroscopes. The protons then radiate radio waves of their own. © 2019 American Association for the Advancement of Scienc

Scientists Mapped Entire Brains at Nanoscale For This Psychadelic Visualization

By David Grossman The brain remains famously remains one of the most mysterious parts of the human body. The challenges of neuroscience are among the most daunting in the medical field. Expansion microscopy is a crucial element of that study, a chemical technique that expands a small specimen to make it more observable at the molecular level. A new technique allows scientists to expand microscopy so instead of focusing a single sell, it can explore full neural circuits, at a speed around 1,000 times faster than before. A struggle in studying live cells is watching them without altering their actions. Scientists work around this problem by using thin sheets of light to illuminate cells with a piece of complex technology called a lattice light sheet microscope. By combining this microscope with expansion microscopy, scientists at the Howard Hughes Medical Institute (HHMI) were able to expand the possibility of how they could study insect brains. “I thought they were full of it,” says Eric Betzig, now an HHMI investigator at the University of California, Berkeley, in a press statement. "They" refers to Ruixuan Gao and Shoh Asano of MIT, who wanted to use Betzig's lab to attempt their combining of the two practices. While a complex procedure involving high-end scientific equipment, at its heart “the idea does sound a bit crude,” Gao says. “We’re stretching tissues apart." When the experiment was over, Betzig says, “I couldn’t believe the quality of the data I was seeing. You could have knocked me over with a feather.” ©2019 Hearst Magazine Media, Inc

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System
Related chapters from MM:Chapter 1: Cells and Structures: The Anatomy of the Nervous System
Link ID: 25886 - Posted: 01.21.2019

New ways to image and control nerve cells could unlock brain mysteries

Laura Sanders Using laser light, ballooning tissue and innovative genetic tricks, scientists are starting to force brains to give up their secrets. By mixing and matching powerful advances in microscopy and cell biology, researchers have imaged intricate details of individual nerve cells in fruit flies and mice, and even controlled small groups of nerve cells in living mice. The techniques, published in two new studies, represent big steps forward for understanding how the brain operates, says molecular neuroscientist Hongkui Zeng of the Allen Institute for Brain Science in Seattle. “Without this kind of technology, we were only able to look at the soup level,” in which diverse nerve cells, or neurons, are grouped and analyzed together, she says. But the new studies show that nerve cells can be studied individually. That zoomed-in approach will begin to uncover the tremendous diversity that’s known to exist among cells, says Zeng, who was not involved in the research. “That is where the field is going. It’s very exciting to see that technologies are now enabling us to do that,” she says. These novel abilities came from multiple tools. At Howard Hughes Medical Institute’s Janelia Research Campus in Ashburn, Va., physicist Eric Betzig and his colleagues had developed a powerful microscope that can quickly peer deep into layers of brain tissue. Called a lattice light sheet microscope, the rig sweeps a thin sheet of laser light down through the brain, revealing cells’ structures. But like any microscope, it hits a wall when structures get really small, unable to resolve the most minute aspects of the scene. |© Society for Science & the Public 2000 - 2019.

Where To Find Some Of The Most Stunning Neuroscience Images Of 2018

Fiona McMillan Your brain has worked hard in 2018, so as the year draws to a close, take a moment to appreciate not only your marvelous network of brain cells, but those found in other species, too. Below is a list of where to find some of the year’s most stunning neuroscience images that reveal the hidden world of neurons in brilliant and breathtaking detail. In order to understand how the brain works, neuroscientists need to take a close look at how neuron networks are wired together. However this isn’t easy, after all just one cubic millimeter in the brain’s cerebral cortex contains around 50,000 neurons each making 6,000 connections with other neurons (give or take a few). Tracing a single network through this incredibly complex web is painstaking work. So, in recent years, researchers developed the Brainbow, a technique that allows individual neurons to be labelled with different fluorescent colors. Unfortunately, it still took months to trace the path of a single neuron across the mouse brain. To address this, in 2018 Takeshi Imai and his colleagues at Kyushu University, Kyoto University and the RIKEN Center for Developmental Biology in Japan took it to the next level. They developed the Tetbow, a method that produces extremely vivid colors enabling scientists to trace neuronal wiring across the whole mouse brain within a matter of days. Also, it’s really pretty. Tetbow provides colorful view of the olfactory bulbRichi Sakaguchi, Marcus N Leiwe, Takeshi Imai published in eLife Sciences under a Creative Commons CC BY 4.0 ©2019 Forbes Media LLC

Guitarist Has Brain Surgery, and Strums All the Way Through

By Kimon de Greef CAPE TOWN — A musician from South Africa had a tumor in his brain, so doctors opened a hole in his skull to remove it. But they had a crucial request: He must play his acoustic guitar during the surgery. The musician, Musa Manzini, a jazz bassist, was awake when the doctors performed the surgery last week, and video footage from the local media site News24 shows him strumming an acoustic guitar slowly as they operated. The technique, known as “awake craniotomy,” allows doctors to operate on delicate areas of the brain — like the right frontal lobe, the site of Mr. Manzini’s tumor — without causing damage. Presumably, had he hit a wrong note, it would have been an immediate signal for the surgeons to probe elsewhere. “It can be very difficult to tell the difference between the tumor and normal brain tissue,” said Dr. Basil Enicker, a specialist neurosurgeon who led the operation at Inkosi Albert Luthuli Central Hospital, in the coastal city of Durban. “Once you’re near a critical area, you can pick it up early, because he will tell you.” The surgery is not unusual. The first craniotomies date to prehistoric times, with fossil records showing that patients had holes drilled in their skulls — and survived — as early as 8,000 years ago. In the 1930s, the Canadian-American neurosurgeon Wilder Penfield pioneered modern craniotomies, which he used to treat epilepsy. The procedure has become fairly common globally since then, posing no greater technical challenge than regular brain surgery, Dr. Enicker said. But choosing patients is very important: People who cough, for example, or who cannot lie still for extended periods, are far more dangerous to operate on. © 2018 The New York Times Company

Image of the Day: Mosquito Brain

Researchers at Howard Hughes Medical Institute (HHMI) have mapped the neuroanatomical regions of the brain of a female mosquito (Aedes aegypti). The researchers constructed the map of groups of neurons by immunostaining the mosquito’s brain for Brp, a synaptic protein, and imaged the brain with confocal microscopy. The atlas was made freely available online on January 31st. “We are trying to build the field of mosquito neurobiology,” says HHMI neurobiologist Leslie Vosshall, who led the work, in a press release. She says she hopes that the new atlas will let mosquito researchers from around the world share data and better understand which parts of the mosquito brain direct different behaviors. “Somewhere in that female brain is the drive to sense humans, fly toward humans, land on humans, and bite and drink the blood of humans,” she says. “Somewhere in that brain is where decision making, motivation, and hunger reside.” © 1986 - 2018 The Scientist

Transparent tissues bring cells into focus for microscopy

Michael Eisenstein In March, researchers in Japan mapped the cellular organization of the mouse brain in unprecedented detail. Systems biologist Hiroki Ueda at the RIKEN Center for Biosystems Dynamics Research in Osaka, Japan, and his team created an atlas of the mouse brain using a technique called CUBIC-X, in which they chemically labelled every cell in the brain, then rendered the organ crystal-clear while also expanding its size tenfold1. From there, they used sophisticated imaging techniques to compile a comprehensive 3D neuronal survey — of some 72 million cells in all, Ueda says. The resulting atlas reduces the brain to a compact database of cellular addresses, which the team used to explore changes in various brain regions during development. Moving forward, the atlas could drive deeper explorations of brain structures that control behaviours such as the sleep–wake cycle. CUBIC-X is just one component in a growing toolbox of such methods, which exploit readily available chemicals to provide researchers with a window not just into the brain, but into virtually every organ in the body. Some are tissue-clearing methods that make opaque tissues transparent, whereas others complement tissue clearing with a proportional size increase that exposes molecular details to conventional microscopy. The choice comes down to the scientific question. There are many ways to achieve similar ends, and users should investigate the strengths and limitations of different methods before deciding which to use. The hunger for tissue-clearing techniques originated with neuroscientists, who were frustrated by their limited ability to trace the snaking routes of axons and dendrites in the brain. © 2018 Springer Nature Publishing AG

Do Brain Waves Conduct Neural Activity Like a Symphony?

By R. Douglas Fields SAN DIEGO—In the textbook explanation for how information is encoded in the brain, neurons fire a rapid burst of electrical signals in response to inputs from the senses or other stimulation. The brain responds to a light turning on in a dark room with the short bursts of nerve impulses, called spikes. Each close grouping of spikes can be compared to a digital bit, the binary off-or-on code used by computers. Neuroscientists have long known, though, about other forms of electrical activity present in the brain. In particular, rhythmic voltage fluctuations in and around neurons—oscillations that occur at the same 60-cycle-per-second frequency as AC current in the U.S.—have caught the field’s attention. These gamma waves encode information by changing a signal’s amplitude, frequency or phase (relative position of one wave to another)—and the rhythmic voltage surges influence the timing of spikes. Heated debate has arisen in recent years as to whether these analog signals, akin to the ones used to broadcast AM or FM radio, may play a role in sorting, filtering and organizing the information flows required for cognitive processes. They may be instrumental in perceiving sensory inputs, focusing attention, making and recalling memories and coupling various cognitive processes into one coherent scene. It is thought that populations of neurons that oscillate at gamma frequencies may unite the neural activity in the same way the violin section of an orchestra is coupled together in time and rhythm with the percussion section to create symphonic music. When gamma waves oscillate in resonance, “you get very rich repertoires of behaviors,” says Wolf Singer, a neuroscientist at the Ernst Strüngmann Institute in Frankfurt, Germany, who researches gamma waves. Just as your car’s dashboard will vibrate in sync with the motor vibrating at a resonant frequency, so too can separate populations of neurons couple in resonance. © 2018 Scientific American

With Brain Implants, Scientists Aim to Translate Thoughts into Speech

By Sharon Begley, The brain surgeon began as he always does, making an incision in the scalp and gently spreading it apart to expose the skull. He then drilled a 3-inch circular opening through the bone, down to the thick, tough covering called the dura. He sliced through that, and there in the little porthole he’d made was the glistening, blood-flecked, pewter-colored brain, ready for him to approach the way spies do a foreign embassy: He bugged it. Dr. Ashesh Mehta, a neurosurgeon at the Feinstein Institute for Medical Research on Long Island, was operating on his epilepsy patient to determine the source of seizures. But the patient agreed to something more: to be part of an audacious experiment whose ultimate goal is to translate thoughts into speech. While he was in there, Mehta carefully placed a flat array of microelectrodes on the left side of the brain’s surface, over areas involved in both listening to and formulating speech. By eavesdropping on the electrical impulses that crackle through the gray matter when a person hears in the “mind’s ear” what words he intends to articulate (often so quickly it’s barely conscious), then transmitting those signals wirelessly to a computer that decodes them, the electrodes and the rest of the system hold the promise of being the first “brain-computer interface” to go beyond movement and sensation. If all goes well, it will conquer the field’s Everest: developing a brain-computer interface that could enable people with a spinal cord injury, locked-in syndrome, ALS, or other paralyzing condition to talk again. © 2018 Scientific America

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System; Chapter 19: Language and Lateralization
Related chapters from MM:Chapter 1: Cells and Structures: The Anatomy of the Nervous System; Chapter 15: Language and Lateralization
Link ID: 25708 - Posted: 11.21.2018

‘Invisible’ mice reveal anatomical secrets

Sara Reardon A new technique that makes dead mice transparent and hard like plastic is giving researchers an unprecedented view of how different types of cell interact in the body. The approach lets scientists pinpoint specific tissues within an animal while scanning its entire body. The approach, called vDISCO, has already revealed surprising structural connections between organs, including hints about the extent to which brain injuries affect the immune system and nerves in other parts of the body. That could lead to better treatments for traumatic brain injury or stroke. Methods that turn entire organs clear have become popular in the past few years, because they allow scientists to study delicate internal structures without disturbing them. But removing organs from an animal’s body for analysis can make it harder to see the full effect of an injury or disease. And if scientists use older methods to make an entire mouse transparent, it can be difficult to ensure that the fluorescent markers used to label cells reach the deepest parts of an organ. The vDISCO technique overcomes many of these problems. By making the dead mice rigid and see-through, it can preserve their bodies for years, down to the structure of individual cells, says Ali Ertürk, a neuroscientist at Ludwig Maximilian University of Munich in Germany, who led the team that developed vDISCO. He presented the work this week at a meeting of the Society for Neuroscience in San Diego, California. © 2018 Springer Nature Limited.

Brain cancer: drink that makes tumours glow could make surgery more effective

Surgeons have tested the use of a fluorescent marker that can help them remove dangerous brain tumour cells from patients more accurately. The research was carried out on people who had suspected glioblastoma, the disease that killed British politician Dame Tessa Jowell in May, and the most common form of brain cancer. Treatment usually involves surgery to remove as much of the cancer as possible, but it can be challenging for surgeons to identify all the cancer cells while avoiding healthy brain tissue. Researchers said using the fluorescent marker helped distinguish the most aggressive cancer cells from other brain tissue and they hope this will ultimately improve patient survival. They used a compound called 5-aminolevulinic acid or 5-ALA, which the patient drinks. The compound glows pink when a light is shone on it. Previous research shows that 5-ALA accumulates in fast-growing cancer cells so it can act as a fluorescent marker of high-grade cells. The study was carried out on 99 patients with suspected high-grade gliomas – a kind of tumour –who were treated at Royal Liverpool hospital, King’s college hospital in London and Addenbrooke’s hospital in Cambridge. They were aged between 23 and 77, with an average age of 59. During their operations, surgeons reported seeing fluorescence in 85 patients and 81 of these were subsequently confirmed by pathologists to have high-grade disease. One was found to have low-grade disease and three could not be assessed. © 2018 Guardian News and Media Limited

Using Temperature-Sensitive Channels to Study Neural Circuitry

Devika G. Bansal Tools that use light, drugs, or temperature to make neurons fire or rest on command have become a mainstay in neuroscience. Thermogenetics, which enables neurons to respond to temperature shifts, first took off with fruit flies about a decade ago, but is emerging as a new trick to manipulate the neural functioning of other model organisms. That’s due to some advantages it affords over optogenetics—the light-based technique that started it all. Genetic toolkits such as thermogenetics and optogenetics follow a basic recipe: scientists pick a receptor that responds to an external cue such as temperature or light, express the receptor in specific neurons as a switch that changes the cell’s voltage—triggering or inhibiting firing—and then use the cue to turn the neural switch on or off. Optogenetics revolutionized our understanding of how the brain’s wiring affects animal behavior. But it comes with drawbacks. For one, delivering light into the deepest regions of the brains of nontransparent animals is a challenge. In mice, this requires surgically inserting optical fibers into the brain, tethering the animal to the light source. Researchers working with adult fruit flies can cut a window through the head cuticle to access the brain. In both cases, the necessary experimental setups are invasive and often time and effort intensive. Additionally, the light intensity required for optogenetics tends to damage tissue. “You pump a lot of light through the optical fiber to activate neurons,” says Vsevolod Belousov, a biochemist at the Russian Academy of Sciences in Moscow who develops thermogenetic tools. “In general, this is not avoidable.” © 1986 - 2018 The Scientist

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System; Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 1: Cells and Structures: The Anatomy of the Nervous System; Chapter 5: The Sensorimotor System
Link ID: 25636 - Posted: 11.02.2018

Revealed: New Cortical Neuron Types

Ashley P. Taylor Two studies in mice published today (October 31) in Nature report the existence of several types of brain cells that had not been acknowledged before. These cell types are distinguished by their gene expression patterns, and within one cortical area, they perform distinct functions. For the gene expression study, led by the Allen Institute’s Hongkui Zeng, researchers performed single-cell RNA sequencing on more than 20,000 cells, most of which were neurons, in the visual cortex and the anterior lateral motor cortex of the mouse brain. Using this method, they identified 133 distinct cell types, both excitatory and inhibitory. They found that the various inhibitory neurons were present in both cortical areas but that the excitatory cell types kept to specific regions, as neuroscientists Aparna Bhaduri and Tomasz Nowakowski of the University of California, San Francisco, describe in an accompanying Nature commentary. “When we see not only cell types that people have identified before, but a number of new ones that are showing up in the data, it’s really exciting for us,” says Zeng in a press release. “It’s like we are able to put all the different pieces of the puzzle The other study, led by Karel Svoboda of the Janelia Research Campus of the Howard Hughes Medical Institute, examined the functions of two subtypes identified through the gene-expression study. These are excitatory cells called pyramidal tract neurons that reside within layer five of the anterior lateral motor cortex in mice. The researchers used optogenetics to activate either one neuronal subtype or the other in mice and at the same time monitored the activity of the two types of neurons during movement. They found that pyramidal tract neurons in the upper part of layer five seem to be involved in preparing for movement, whereas those in the lower part of layer five help execute it. © 1986 - 2018 The Scientist

Web service makes big data available to neuroscientists

Jeffrey M. Perkel Randal Burns recalls that the brain-science community was “abuzz” in 2011. Burns, a computer scientist at Johns Hopkins University in Baltimore, Maryland, was focusing on astrophysics and fluid dynamics data management at the time. But he was intrigued when Joshua Vogelstein, a neuroscientist and colleague at Johns Hopkins, told him that the first large-scale neural-connectivity data sets had just been collected and asked for his help to present them online. “It was the first time that you had data of that quality, at that resolution and scale, where you had the sense that you could build a neural map of an interesting portion of the brain,” says Burns. Vogelstein worked with Burns to build a system that would make those data — 20 trillion voxels’ worth — available to the larger neuroscience community. The team has now generalized the software to support different classes of imaging data and describes the system this week (J. T. Vogelstein et al. Nature Meth. 15, 846-847; 2018). NeuroData is a free, cloud-based collection of web services that supports large-scale neuroimaging data, from electron microscopy to magnetic resonance imaging and fluorescence photomicrographs. Key to its functionality, Vogelstein says, is the spatial database bossDB, which allows researchers to retrieve images of any section of the brain, at any resolution, and in several standard formats. Users can then explore those data using a tool known as Neuroglancer. As they navigate the images, the URL changes to reflect their specific view, allowing them to share particular visualizations with their colleagues. “These links become a core part of the way in which we communicate and pass data back and forth to one another,” says Forrest Collman, a neuroscientist at the Allen Institute for Brain Science in Seattle, Washington, and a co-author of the paper. © 2018 Springer Nature Limited.

The world’s strongest MRI machines are pushing human imaging to new limits

Anna Nowogrodzki On a cold morning in Minneapolis last December, a man walked into a research centre to venture where only pigs had gone before: into the strongest magnetic resonance imaging (MRI) machine built to scan the human body. First, he changed into a hospital gown, and researchers made sure he had no metal on his body: no piercings, rings, metal implants or pacemakers. Any metal could be ripped out by the immensely powerful, 10.5-tesla magnet — weighing almost 3 times more than a Boeing 737 aeroplane and a full 50% more powerful than the strongest magnets approved for clinical use. Days earlier, he had passed a check-up that included a baseline test of his sense of balance to make sure that any dizziness from exposure to the magnets could be assessed properly. In the MRI room at the University of Minnesota’s Center for Magnetic Resonance Research, he lay down inside a 4-metre-long tube, surrounded by 110 tonnes of magnet and 600 tonnes of iron shielding, for an hour’s worth of imaging of his hips, whose thin cartilage would test the limits of the machine’s resolution. The centre’s director, Kamil Ugurbil, had been waiting for years for this day. The magnet faced long delays because the liquid helium needed to fill it was in short supply. After the machine was finally delivered, on a below-freezing day in 2013, it took four years of animal testing and ramping up the field strength before Ugurbil and his colleagues were comfortable sending in the first human. Even then, they didn’t quite know what they’d see. But it was worth the wait: when the scan materialized on screen, the fine resolution revealed intricate details of the wafer-thin cartilage that protects the hip socket. “It was extremely exciting and very rewarding,” Ugurbil says. © 2018 Springer Nature Limited

My thoughts are my password, because my brain reactions are unique

Wenyao Xu Your brain is an inexhaustible source of secure passwords – but you might not have to remember anything. Passwords and PINs with letters and numbers are relatively easily hacked, hard to remember and generally insecure. Biometrics are starting to take their place, with fingerprints, facial recognition and retina scanning becoming common even in routine logins for computers, smartphones and other common devices. They’re more secure because they’re harder to fake, but biometrics have a crucial vulnerability: A person only has one face, two retinas and 10 fingerprints. They represent passwords that can’t be reset if they’re compromised. Like usernames and passwords, biometric credentials are vulnerable to data breaches. In 2015, for instance, the database containing the fingerprints of 5.6 million U.S. federal employees was breached. Those people shouldn’t use their fingerprints to secure any devices, whether for personal use or at work. The next breach might steal photographs or retina scan data, rendering those biometrics useless for security. Our team has been working with collaborators at other institutions for years, and has invented a new type of biometric that is both uniquely tied to a single human being and can be reset if needed. When a person looks at a photograph or hears a piece of music, her brain responds in ways that researchers or medical professionals can measure with electrical sensors placed on her scalp. We have discovered that every person’s brain responds differently to an external stimulus, so even if two people look at the same photograph, readings of their brain activity will be different. © 2010–2018, The Conversation US, Inc.

What Makes Human Brain Cells Unique?

By Diana Kwon Spanish neuroscientist Santiago Ramón y Cajal revolutionized the study of the brain when he observed neurons for the first time. His investigations, now more than 100 years old, revealed intricate details of nerve cells in many different animals, including humans—rootlike dendrites attached to bulbous cell bodies, from which extend long, slender axons. Cajal’s examinations also revealed dendrites (via which nerve cells receive signals from other neurons) were much longer in humans than in rodents and other animals, even other non-human primates. A new study, published this week in Cell, shows that in people these antennalike projections also have distinct electrical properties that may help explain how the brain processes arriving information. Scientists have been meticulously studying dendrites in the decades since Cajal’s initial observations. Still, “the only thing we really knew about human dendrites was their anatomy,” Massachusetts Institute of Technology neuroscientist Mark Harnett says. “There was a lot of potential for human dendrites to be doing something different because of their length, but there was no published work, as far as I know, on their actual electrical properties.” So Harnett and his colleagues set out to investigate whether the length of dendrites affected electrical signals transmitted through them. With the help of a neurologist, Sydney Cash of Massachusetts General Hospital, they were able to obtain brain tissue that had been removed from epilepsy patients undergoing routine surgery to help allay seizures—a procedure in which physicians routinely remove part of the temporal cortex to get to the hippocampus, a structure deep inside the brain where seizures typically originate. © 2018 Scientific American

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 1: Cells and Structures: The Anatomy of the Nervous System
Link ID: 25594 - Posted: 10.20.2018

The Fidgeting Brain

By Neuroskeptic A new review paper in The Neuroscientist highlights the problem of body movements for neuroscience, from blinks to fidgeting. Authors Patrick J Drew and colleagues of Penn State discuss how many types of movements are associated with widespread brain activation, which can contaminate brain activity recordings. This is true, they say, of both humans and experimental animals such as rodents, e.g. with their ‘whisking’ movements of the whiskers. A particular concern is that many movements occur (or change in frequency) over similar timescales to some measures of neural activity – especially resting state fMRI – which means that movement-related activity could be mistaken for more interesting neural signals. Here’s how the authors describe the relationship between one kind of movement, blinking, and brain activity: Blink-related modulations are visible in BOLD functional magnetic resonance imaging (fMRI) signals in the primary visual cortex, as well as higher brain regions, such as the frontal eye field (FEF), and regions associated with the default network and somatosensory areas… If the rate of blinking were constant, ongoing blinks would not be an issue, and they would simply be averaged out. However, spontaneous eye blink rate dynamically varies on slow time scales (~0.001 Hz to 0.1 Hz), and these variations can drive correlated activity in multiple brain regions.

“Bar Codes” Could Trace Errant Brain Wiring in Autism and Schizophrenia

By Simon Makin Neuroscientists know a lot about how individual neurons operate but remarkably little about how large numbers of them work together to produce thoughts, feelings and behavior. They need a wiring diagram for the brain—known as a connectome—to identify the circuits that underlie the organ’s functions. Now researchers at Cold Spring Harbor Laboratory and their colleagues have developed an innovative brain-mapping technique and used it to trace the connections emanating from nearly 600 neurons in a mouse brain’s main visual area in just three weeks. This technology could someday be used to help understand disorders thought to involve atypical brain wiring, such as autism or schizophrenia. The technique works by tagging cells with genetic “bar codes.” Researchers inject viruses into mice brains, where the viruses direct cells to produce random 30-letter RNA sequences (consisting of the nucleotide “letters” G, A, U and C). The cells also create a protein that binds to these RNA bar codes and drags them the length of each neuron’s output wire, or axon. The researchers later dissect the mice brains into target regions and sequence the cells in each area, enabling them to determine which tagged neurons are connected to which regions. The team found that neurons in a mouse’s primary visual cortex typically send outputs to multiple other visual areas. It also discovered that most cells fall into six distinct groups based on which regions—and how many of them—they connect to. This finding suggests there are subtypes of neurons in a mouse’s primary visual cortex that perform different functions. “Because we have so many neurons, we can do statistics and start understanding the patterns we see,” says Cold Spring Harbor’s Justus Kebschull, co-lead author of the study, which was published in April in Nature. © 2018 Scientific American

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 1: Cells and Structures: The Anatomy of the Nervous System; Chapter 4: Development of the Brain
Link ID: 25527 - Posted: 10.04.2018

A new way to capture the brain’s electrical symphony

Giorgia Guglielmi Biophysicist Adam Cohen was strolling around San Francisco, California, in 2010, when a telephone call caught him by surprise. “We have a signal,” said the caller. Nearly 5,000 kilometres away, in Cambridge, Massachusetts, his collaborators had struck gold. After months of failed experiments, the researchers had found a fluorescent protein that allowed them to watch signals as they passed between neurons. But there was something weird going on. When Cohen got back to his lab at Harvard University, he learned that all the recordings of the experiment showed a strange progression. At first, neurons decorated with the protein flashed nicely as electric impulses whizzed through them. But then the cells turned into bright blobs. “Halfway through each recording, the signal would go all wild,” Cohen says. So he decided to join his team during an experiment. “When they started the recording, they would sit there holding their breath,” Cohen says. But as soon as they realized it was working, they would celebrate, “dancing and running around the room”. In their exuberance, they were letting the light from a desk lamp shine right onto the microscope. “We were actually recording our excitement,” says Daniel Hochbaum, then a graduate student in Cohen’s group. They toned down their celebrations, and a year later, the team published its study1 — one of the first to show that a fluorescent protein engineered into specific mammalian neurons could be used to track individual electric impulses in real time. © 2018 Springer Nature Limited

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