PRESS-NEWS.org - Press Release Distribution
PRESS RELEASES DISTRIBUTION

Making connections in the eye

Wiring diagram of retinal neurons is first step toward mapping the human brain

2013-08-08
(Press-News.org) CAMBRIDGE, MA -- The human brain has 100 billion neurons, connected to each other in networks that allow us to interpret the world around us, plan for the future, and control our actions and movements. MIT neuroscientist Sebastian Seung wants to map those networks, creating a wiring diagram of the brain that could help scientists learn how we each become our unique selves.

In a paper appearing in the Aug. 7 online edition of Nature, Seung and collaborators at MIT and the Max Planck Institute for Medical Research in Germany have reported their first step toward this goal: Using a combination of human and artificial intelligence, they have mapped all the wiring among 950 neurons within a tiny patch of the mouse retina.

Composed of neurons that process visual information, the retina is technically part of the brain and is a more approachable starting point, Seung says. By mapping all of the neurons in this 117-micrometer-by-80-micrometer patch of tissue, the researchers were able to classify most of the neurons they found, based on their patterns of wiring. They also identified a new type of retinal cell that had not been seen before.

"It's the complete reconstruction of all the neurons inside this patch. No one's ever done that before in the mammalian nervous system," says Seung, a professor of computational neuroscience at MIT.

Other MIT authors of the paper are former postdoc Srinivas Turaga and former graduate student Viren Jain. The Max Planck team was led by Winfried Denk, a physicist and the Max Planck Institute's director. Moritz Helmstaedter, a research group leader at the Max Planck Institute, is the lead author of the paper, and Kevin Briggman, a former postdoc at Max Planck, is also an author.

Tracing connections

Neurons in the retina are classified into five classes: photoreceptors, horizontal cells, bipolar cells, amacrine cells and ganglion cells. Within each class are many types, classified by shape and by the connections they make with other neurons.

"Neurons come in many types, and the retina is estimated to contain 50 to 100 types, but they've never been exhaustively characterized. And their connections are even less well known," Seung says.

In this study, the research team focused on a section of the retina known as the inner plexiform layer, which is one of several layers sandwiched between the photoreceptors, which receive visual input, and the ganglion cells, which relay visual information to the brain via the optic nerve. The neurons of the inner plexiform layer help to process visual information as it passes from the surface of the eye to the optic nerve.

To map all of the connections in this small patch of retina, the researchers first took electron micrographs of the targeted section. The Max Planck researchers obtained these images using a technique called serial block face scanning electron microscopy, which they invented to generate high-resolution three-dimensional images of biological samples.

Developing a wiring diagram from these images required both human and artificial intelligence. First, the researchers hired about 225 German undergraduates to trace the "skeleton" of each neuron, which took more than 20,000 hours of work (a little more than two years).

To flesh out the bodies of the neurons, the researchers fed these traced skeletons into a computer algorithm developed in Seung's lab, which expands the skeletons into full neuron shapes. The researchers used machine learning to train the algorithm, known as a convolutional network, to detect the boundaries between neurons. Using those as reference points, the algorithm can fill in the entire body of each neuron.

"Tracing neurons in these images is probably one of the world's most challenging computer vision problems. Our convolutional networks are actually deep artificial neural networks designed with inspiration from how our own visual system processes visual information to solve these difficult problems," Turaga says. If human workers were to fill in the entire neuron body, it would take 10 to 100 times longer than just drawing the skeleton. "This speeds up the whole process," Seung says. "It's a way of combining human and machine intelligence."

The only previous complete wiring diagram, which mapped all of the connections between the 302 neurons found in the worm Caenorhabditis elegans, was reported in 1986 and required more than a dozen years of tedious labor.

Classifying neurons

Wiring diagrams allow scientists to see where neurons connect with each other to form synapses — the junctions that allow neurons to relay messages. By analyzing how neurons are connected to each other, researchers can classify different types of neurons.

The researchers were able to identify most of the 950 neurons included in the new retinal-wiring diagram based on their connections with other neurons, as well as the shape of the neuron. A handful of neurons could not be classified because there was only one of their type, or because only a fragment of the neuron was included in the imaged sample.

"We haven't completed the project of classifying types but this shows that it should be possible. This method should be able to do it, in principle, if it's scaled up to a larger piece of tissue," Seung says.

In this study, the researchers identified a new class of bipolar cells, which relay information from photoreceptors to ganglion cells. However, further study is needed to determine this cell type's exact function.

Seung's lab is now working on a wiring diagram of a larger piece of the retina — 0.3 millimeter by 0.3 millimeter — using a slightly different approach. In that study, the researchers first feed their electron micrographs into the computer algorithm, then ask human volunteers to check over the computer's work and correct mistakes through a crowd-sourcing project known as EyeWire. ### The research was funded by the Max Planck Society, the Howard Hughes Medical Institute and the Gatsby Charitable Foundation.

Written by Anne Trafton, MIT News Office


ELSE PRESS RELEASES FROM THIS DATE:

NASA sees 10-mile-high thunderstorms in Hurricane Henriette

2013-08-08
VIDEO: This 3-D image (looking toward the east) from TRMM PR data reveals that towering storms in the northeastern side of Henriette's eye were reaching height of almost 16.75km (~10.41 miles).... Click here for more information. NASA's TRMM satellite peered into the clouds of Hurricane Henriette as is continues moving through the Eastern Pacific Ocean, and found powerful thunderstorms that topped 10 miles high. The higher the thunderstorms are, the more powerful the uplift ...

NASA satellite sees Tropical Storm Mangkhut making Vietnam landfall

2013-08-08
Tropical Storm Mangkhut had some strong thunderstorms around its center as it began making landfall in northern Vietnam on Aug. 7. Infrared data from NASA's Aqua satellite showed very cold cloud top temperatures of those strong thunderstorms as it passed overhead. On Aug. 6 at 20:55 UTC (4:55 p.m. EDT) NASA's Aqua satellite flew over Mangkhut as it tracked west-northwest through the Gulf of Tonkin on its way to a landfall. Aqua's Atmospheric Infrared Sounder or AIRS instrument captured infrared data that showed that cloud top temperatures of some thunderstorms around ...

DNA nanorobots find and tag cellular targets

2013-08-08
NEW YORK, NY (August 7, 2013) — Researchers at Columbia University Medical Center, working with their collaborators at the Hospital for Special Surgery, have created a fleet of molecular "robots" that can home in on specific human cells and mark them for drug therapy or destruction. The nanorobots—a collection of DNA molecules, some attached to antibodies —were designed to seek a specific set of human blood cells and attach a fluorescent tag to the cell surfaces. Details of the system were published July 28, 2013, in the online edition of Nature Nanotechnology. "This ...

New research suggests glaucoma screenings for sleep apnea sufferers

2013-08-08
SAN FRANCISCO – August 7, 2013 – Researchers in Taiwan have discovered that people with sleep apnea are far more likely to develop glaucoma compared to those without the sleep condition. The results of this study, which is the first to calculate the risk of the disease among people with the sleep disorder following diagnosis, is published in this month's edition of Ophthalmology, the journal of the American Academy of Ophthalmology. Conducted by researchers at Taipei Medical University, the retrospective study, "Obstructive Sleep Apnea and Increased Risk of Glaucoma," ...

Cognitive decline with age is normal, routine -- but not inevitable

2013-08-08
CORVALLIS, Ore. – If you forget where you put your car keys and you can't seem to remember things as well as you used to, the problem may well be with the GluN2B subunits in your NMDA receptors. And don't be surprised if by tomorrow you can't remember the name of those darned subunits. They help you remember things, but you've been losing them almost since the day you were born, and it's only going to get worse. An old adult may have only half as many of them as a younger person. Research on these biochemical processes in the Linus Pauling Institute at Oregon State ...

Infrared NASA image revealed fading Gil's warming cloud tops

2013-08-08
As cloud tops fall, their temperature rises, and infrared data from NASA's Aqua satellite saw that happening as Tropical Storm Gil weakened. The Atmospheric Infrared Sounder or AIRS instrument captured an infrared picture of Tropical Storm Gil on Aug. 6 at 22:59 UTC (6:59 p.m. EDT). The AIRS data showed that cloud top temperatures had warmed since the day before, indicating that the thunderstorms that make up the tropical cyclone didn't have as much punch, or uplift to form more powerful storms. AIRS imagery is false-colored to show temperature and is created at NASA's ...

Type 1 diabetes drug strikingly effective in clinical trial

2013-08-08
An experimental drug designed to block the advance of type 1 diabetes in its earliest stages has proven strikingly effective over two years in about half of the patients who participated in the phase 2 clinical trial. Patients who benefited most were those who still had relatively good control of their blood sugar levels and only a moderate need for insulin injections when the trial began. With the experimental drug, teplizumab, they were able to maintain their level of insulin production for the full two years -- longer than with most other drugs tested against ...

Oregon burning

2013-08-08
On July 26, 2013, thunderstorms passed over southern Oregon, and lightning ignited dozens of difficult-to-control wildfires. Persistently dry weather since the beginning of 2013 had primed forests to burn, and nearly all of southern Oregon was in a state of severe or moderate drought. In early August, forecasters were expecting the situation to worsen. On August 5, 2013, the Moderate Resolution Imaging Spectroradiometer (MODIS) on Aqua captured the top image, which shows smoke rising from the Douglas Complex fire and the Big Windy Complex fire in southern Oregon. To the ...

Study explores effects of review setting on scientific peer review

2013-08-08
RESTON, VIRGINIA – Research findings published today in PLOS ONE report that the setting in which a scientific peer review panel evaluates grant applications does not necessarily impact the outcome of the review process. However, the research found that the average amount of discussion panelists engage in during the review is reduced. The investigation examined more than 1,600 grant application reviews coordinated by the American Institute of Biological Sciences Scientific Peer Advisory and Review Services (AIBS SPARS) on behalf of a federal agency over a four-year period. ...

Heat intensifies Siberian wildfires

2013-08-08
The summer of 2012 was the most severe wildfire season Russia had faced in a decade. 2013 might be headed in the same direction after an unusual heat wave brought a surge of fire activity in northern Siberia in July. A persistent high-pressure weather pattern in the Russian Arctic—a blocking high—contributed to the heat wave, which saw temperatures reach 32° Celsius (90° Fahrenheit) in the northern city of Norilsk. For comparison, daily July highs in Norilsk average 16° Celsius (61° Fahrenheit). Blocking highs are so named because they block the jet stream from moving ...

LAST 30 PRESS RELEASES:

Being physically active, even just a couple of days a week, may be key to better health

High-fat diet promote breast cancer metastasis in animal models

A router for photons

Nurses and AI collaborate to save lives, reduce hospital stays

Multi-resistance in bacteria predicted by AI model

Tinker Tots: A citizen science project to explore ethical dilemmas in embryo selection

Sensing sickness

Cost to build multifamily housing in California more than twice as high as in Texas

Program takes aim at drinking, unsafe sex, and sexual assault on college campuses

Inability to pay for healthcare reaches record high in U.S.

Science ‘storytelling’ urgently needed amid climate and biodiversity crisis

KAIST Develops Retinal Therapy to Restore Lost Vision​

Adipocyte-hepatocyte signaling mechanism uncovered in endoplasmic reticulum stress response

Mammals were adapting from life in the trees to living on the ground before dinosaur-killing asteroid

Low LDL cholesterol levels linked to reduced risk of dementia

Thickening of the eye’s retina associated with greater risk and severity of postoperative delirium in older patients

Almost one in ten people surveyed report having been harmed by the NHS in the last three years

Enhancing light control with complex frequency excitations

New research finds novel drug target for acute myeloid leukemia, bringing hope for cancer patients

New insight into factors associated with a common disease among dogs and humans

Illuminating single atoms for sustainable propylene production

New study finds Rocky Mountain snow contamination

Study examines lactation in critically ill patients

UVA Engineering Dean Jennifer West earns AIMBE’s 2025 Pierre Galletti Award

Doubling down on metasurfaces

New Cedars-Sinai study shows how specialized diet can improve gut disorders

Making moves and hitting the breaks: Owl journeys surprise researchers in western Montana

PKU Scientists simulate the origin and evolution of the North Atlantic Oscillation

ICRAFT breakthrough: Unlocking A20’s dual role in cancer immunotherapy

How VR technology is changing the game for Alzheimer’s disease

[Press-News.org] Making connections in the eye
Wiring diagram of retinal neurons is first step toward mapping the human brain