Scientists create artificial brain out of spongy goo | Science/AAAS | News

Scientists create artificial brain out of spongy goo | Science/AAAS | News: The rings are engineered to mimic the structure and function of the six layers of human cortical brain tissue. Scientists coaxed neurons (right) to grow around stiff, porous matrices made of silk proteins immersed in collagen gel. Then, they colored the layers with food dye and pieced them together like a jigsaw puzzle. By tweaking the size and orientation of matrix pores, researchers attempted to emulate variations of cellular structure and function in a real cortex. Unlike flat neuron cultures grown in petri dishes, the structure provides cells with something to cling to as they branch out and make connections, forming complex, 3D networks that more closely mimic real neural circuits, the authors say.

Physicists eye neural fly data, find formula for Zipf's law

Physicists eye neural fly data, find formula for Zipf's law: ...George Zipf... found that if you rank words in a language in order of their popularity, a strange pattern emerges: The most popular word is used twice as often as the second most popular, and three times as much as the third-ranked word, and so on. This same rank vs. frequency rule was also found to apply to many other social systems...

"We showed mathematically that the system becomes Zipfian when you're recording the activity of many units, such as neurons, and all of the units are responding to the same variable," Nemenman says. "The fact that Zipf's law will occur in a system with just 40 or 50 such units shows that biological units are in some sense special – they must be adapted to the outside world."

Muscle-powered bio-bots walk on command | News Bureau | University of Illinois

Muscle-powered bio-bots walk on command | News Bureau | University of Illinois: The new bio-bots are powered by a strip of skeletal muscle cells that can be triggered by an electric pulse...

“Skeletal muscles cells are very attractive because you can pace them using external signals,” Bashir said. “For example, you would use skeletal muscle when designing a device that you wanted to start functioning when it senses a chemical or when it received a certain signal. To us, it’s part of a design toolbox. We want to have different options that could be used by engineers to design these things.”

The design is inspired by the muscle-tendon-bone complex found in nature. There is a backbone of 3-D printed hydrogel, strong enough to give the bio-bot structure but flexible enough to bend like a joint. Two posts serve to anchor a strip of muscle to the backbone, like tendons attach muscle to bone, but the posts also act as feet for the bio-bot.

Neuron Light Switch Now Goes “On” and “Off” | MIT Technology Review

Neuron Light Switch Now Goes “On” and “Off” | MIT Technology Review: Now, two research groups have engineered new optogenetic proteins that can be used to efficiently silence neurons... His group’s new “off” switch for neurons was created by changing 10 of the 333 amino acids in an existing optogenetic protein, which itself had been engineered by combining natural proteins from green algae. That advance “creates a powerful tool that allows neuroscientists to apply a brake in any specific circuit with millisecond precision...”

Neuroscientists find cortical columns in brain not uniform, challenging large-scale simulation models | KurzweilAI

Neuroscientists find cortical columns in brain not uniform, challenging large-scale simulation models | KurzweilAI: The study was based on recent advances in high-resolution imaging and reconstruction techniques (confocal microscopy and automated image-processing routines)... enabling researchers to automatically and reliably detect the 3D location and type of every nerve cell throughout the entire brain...
“By determining the exact numbers and distributions of nerve cells within almost 100 cortical columns, the substantial differences observed across columns within the same animal argue against the principle of cortical uniformity.”

Nanoscale neuronal activity measured for the first time | KurzweilAI

Nanoscale neuronal activity measured for the first time | KurzweilAI: “The nanopipette hovers above the surface of the sample and scans the structure to reveal its three-dimensional topography. The same nanopipette then attaches to the surface at selected locations on the structure to record electrical activity.

Stem cells mimic human brain : Nature News & Comment

Stem cells mimic human brain : Nature News & Comment: ...in the latest advance, scientists developed bigger and more complex neural-tissue clumps by first growing the stem cells on a synthetic gel that resembled natural connective tissues found in the brain and elsewhere in the body. Then, they plopped the nascent clumps into a spinning bath to infuse the tissue with nutrients and oxygen...

Under a microscope, researchers saw discrete brain regions that seemed to interact with one another. But the overall arrangement of the different proto-brain areas varied randomly across tissue samples — amounting to no recognizable physiological structure.

“The entire structure is not like one brain,” says Knoblich, adding that normal brain maturation in an intact embryo is probably guided by growth signals from other parts of the body. The tissue balls also lacked blood vessels, which could be one reason that their size was limited to 3–4 millimetres in diameter, even after growing for 10 months or more.

How neurons ‘decide’ to create axons or dendrites | KurzweilAI

How neurons ‘decide’ to create axons or dendrites | KurzweilAI: They found that embryonic nerve cells manufacture a signaling enzyme called Atypical Protein Kinase C (aPKC) in two varieties: a full-length one and a shorter one...
When the researchers blocked the production of the short form, the nerve cell grew multiple axons and no dendrites. When they created an artificial abundance of the short form, dendrites formed at the expense of axons.

IBM Scientists Show Blueprints for Brainlike Computing | MIT Technology Review

IBM Scientists Show Blueprints for Brainlike Computing | MIT Technology Review: Modha’s team has also developed software that runs on a conventional supercomputer but simulates the functioning of a massive network of neurosynaptic cores—with 100 trillion virtual synapses and two billion neurosynaptic cores.

Each core of the simulated neurosynaptic computer contains its own network of 256 “neurons,” which operate using a new mathematical model. In this model, the digital neurons mimic the independent nature of biological neurons, developing different response times and firing patterns in response to input from neighboring neurons.

“Programs” are written using special blueprints called corelets. Each corelet specifies the basic functioning of a network of neurosynaptic cores. Individual corelets can be linked into more and more complex structures—nested, Modha says, “like Russian dolls.”

A Videogame That Recruits Players to Map the Brain | Wired Design | Wired.com

A Videogame That Recruits Players to Map the Brain | Wired Design | Wired.com: Created by neuroscientist Sebastian Seung’s lab at MIT, EyeWire basically gamifies the professional research Seung and his collaborators do on a daily basis.

A Near-Whole Brain Activity Map in Fish

A Near-Whole Brain Activity Map in Fish:  The zebrafish larvae, whose bodies are transparent and brains are tiny, were genetically engineered to produce a protein in their neurons that glows in response to the chemical changes that occur when that neuron fires...

With the modified fish and microscopy methods, the researchers were able to capture the activity of at least 80 percent of the baby fish’s 100,000 neurons over a time period of just 1.3 seconds.  

Precisely engineering 3-D brain tissues

Precisely engineering 3-D brain tissues: To mimic this architectural complexity in their engineered tissues, the researchers embedded a mixture of brain cells taken from the primary cortex of rats into sheets of hydrogel. They also included components of the extracellular matrix, which provides structural support and helps regulate cell behavior.

Those sheets were then stacked in layers, which can be sealed together using light to crosslink hydrogels. By covering layers of gels with plastic photomasks of varying shapes, the researchers could control how much of the gel was exposed to light, thus controlling the 3-D shape of the multilayer tissue construct.

This type of photolithography is also used to build integrated circuits onto semiconductors — a process that requires a photomask aligner machine, which costs tens of thousands of dollars. However, the team developed a much less expensive way to assemble tissues using masks made from sheets of plastic, similar to overhead transparencies, held in place with alignment pins.

The tissue cubes can be made with a precision of 10 microns, comparable to the size of a single cell body. At the other end of the spectrum, the researchers are aiming to create a cubic millimeter of brain tissue with 100,000 cells and 900 million connections.

Simulated brain scores top test marks : Nature News & Comment

Simulated brain scores top test marks : Nature News:  It stands apart from other attempts to simulate a brain, such as the ambitious Blue Brain Project (see 'Brain in a box'), because it produces complex behaviours with fewer neurons...


A pure computer simulation, Spaun simulates the physiology of each of its neurons, from spikes of electricity that flow through them to neurotransmitters that cross between them. The computing cells are divided into groups, corresponding to specific parts of the brain that process images, control movements and store short-term memories. These regions are wired together in a realistic way, and even respond to inputs that mimic the action of neurotransmitters.

As Spaun sees a stream of numbers, it extracts visual features so that it can recognize the digits. It can then perform at least eight different tasks, from simple ones like copying an image, to more complex ones similar to those found on IQ tests, such as finding the next number in a series. When finished, it writes out its answer with a physically modelled arm.

Wasp has hints of a clockwork brain

Wasp has hints of a clockwork brain: A tiny wasp has brain cells so small, physics predicts they shouldn't work at all. These miniature neurons might harbour subtle modifications, or they might work completely differently from all other known neurons - mechanically...
...Of 528 axons measured, a third were less than 0.1 micrometre in diameter, an order of magnitude narrower than human axons. The smallest were just 0.045 μm...
...That makes the axon impossibly noisy...
...The tiny axons might each carry a long rigid rod stretching down the centre. Pulling the rod could create a physical rather than electrical trigger for the release of a chemical that passes the signal on to the neighbouring neuron...

Simple mathematical pattern describes shape of neuron ‘jungle’ | KurzweilAI

Simple mathematical pattern describes shape of neuron ‘jungle’ | KurzweilAI: Cajal proposed that neurons spread out their branches so as to use as little wiring as possible to reach other cells in the network...

New work by UCL neuroscientists has revisited this century-old hypothesis using modern computational methods. They show that a simple computer program that connects points with as little wiring as possible can produce tree-like shapes that are indistinguishable from real neurons...

They also show that the shape of neurons follows a simple mathematical relationship called a power law*: dendrites grow to fill a target space in an optimal manner and, similar to a minimum spanning tree, use the least amount of wiring to reach all synaptic contacts.

Pigeons may ‘hear’ magnetic fields : Nature News & Comment

Pigeons may ‘hear’ magnetic fields : Nature News: Individual neurons in birds' brains can relay crucial information about Earth’s magnetic field...

For their latest research, the subject of today's Science paper, Wu and Dickman restrained seven homing pigeons (Columba livia) and placed them in a dark room. A magnetic field was created to cancel Earth’s field, and the researchers then monitored the birds’ brain activity while creating and rotating carefully controlled artificial magnetic fields around the pigeons.

The authors found that vestibular neurons — which are linked to balance systems in the inner ear — fired differentially in response to alterations in the field’s direction, intensity and polarity, and that these cells were especially sensitive to the bandwith that covers Earth’s geo-magnetic field...

“I would say now there are three potential places where magnetoreceptors may rest...”  These are the beak, the eyes and the ears.

Quantum dots control brain cells for the first time

Quantum dots control brain cells for the first time: First, they cultivated prostate cancer cells on a film covered with quantum dots. The cell membranes of the cancer cells were positioned next to the dots. The team then shone light onto the nanoparticles.

Energy from the light excites electrons within the quantum dot which causes the surrounding area to become negatively charged (see diagram). This caused some of the cancer cells' ion channels, which are mediated by a voltage, to open, allowing ions to rush in or out of the cells...

When Lin's team repeated their experiment with nerve cells, they found that stimulating the quantum dots caused ion channels to open and the nerve cell to fire.

More than glue: Glia cells found to regulate synapses

More than glue: Glia cells found to regulate synapses: The brain is like a social network, says Prof. Ben-Jacob. Messages may originate with the neurons, which use the synapses as their delivery system, but the glia serve as an overall moderator, regulating which messages are sent on and when. These cells can either prompt the transfer of information, or slow activity if the synapses are becoming overactive. This makes the glia cells the guardians of our learning and memory processes, he notes, orchestrating the transmission of information for optimal brain function.

Neurons illuminate as they fire, may open new ways to trace brain signals

Neurons illuminate as they fire, may open new ways to trace brain signals: Cohen and his team infected brain cells that had been cultured in the lab with a genetically altered virus that contained the protein-producing gene. Once infected, the cells began manufacturing the protein, allowing them to light up.

When a neuron fires, its voltage reverses for a very short time, about a thousandth of a second, he explained. “This brief spike in voltage travels down the neuron and then activates other neurons downstream. Our protein is sitting in the [outside] membrane of the neurons, so as that pulse washes over the proteins, they light up, giving us an image of the neurons as they fire.”

We can now see how these signals spread through the neuronal network, said Cohen.

Music of the brain: each synapse has its own natural rhythm | KurzweilAI

Music of the brain: each synapse has its own natural rhythm | KurzweilAI: Contrary to what was previously assumed, Mehta and Kumar found that stimulating the neurons at the highest frequencies was not the best way to increase synaptic strength. “To our surprise, we found that beyond the optimal frequency, synaptic strengthening actually declined as the frequencies got higher.”

The knowledge that a synapse has a preferred frequency for maximal learning led the researchers to compare optimal frequencies based on the location of the synapse on a neuron...

The optimal frequency for inducing synaptic learning changed depending on where the synapse was located. The farther the synapse was from the neuron’s cell body, the higher its optimal frequency.

“Incredibly, when it comes to learning, the neuron behaves like a giant antenna, with different branches of dendrites tuned to different frequencies for maximal learning,” Mehta said.