Noninvasive brain control | MIT News Office

Noninvasive brain control | MIT News Office: MIT engineers have now developed the first light-sensitive molecule that enables neurons to be silenced noninvasively, using a light source outside the skull...

Boyden’s team had previously identified two light-sensitive chloride ion pumps that respond to red light, which can penetrate deeper into living tissue. However, these molecules, found in the bacteria Haloarcula marismortui and Haloarcula vallismortis, did not induce a strong enough photocurrent — an electric current in response to light — to be useful in controlling neuron activity.

Chuong set out to improve the photocurrent by looking for relatives of these proteins and testing their electrical activity. She then engineered one of these relatives by making many different mutants. The result of this screen, Jaws, retained its red-light sensitivity but had a much stronger photocurrent — enough to shut down neural activity.

First Movie Of An Entire Brain’s Neuronal Activity — The Physics arXiv Blog — Medium

First Movie Of An Entire Brain’s Neuronal Activity — The Physics arXiv Blog — Medium: ...Schrödel, Prevedel and co developed a way to ensure that the genes only fluoresce in the nucleus of each neuron. That makes active neurons much easier to tell apart...

...light sculpting. This works by bouncing the spot of laser light off a grating that stretches it out. This creates a disc of light that images an area of the brain in one go rather than a single point. In affect, it produces a cross-sectional image of brain activtiy.

The advantage is that the light disc need only be scanned in one direction to capture the whole volume of the brain. And this can be done at a rate that allows the team to film the neuronal activity of the entire brain at a rate of 80 frames per second.

Light Could Restore Lost Hearing - Scientific American

Light Could Restore Lost Hearing - Scientific American: In a study that appeared in March in the Journal of Clinical Investigation, the researchers used viruses to implant genes for light sensitivity into mouse embryos of a deaf lineage. The genes went to work in the auditory pathways of the mouse brains, creating light-sensitive patches on the membranes of their spiral ganglion neurons and other neurons. The scientists then directed LED light onto these neurons and recorded brain stem activity—an essential integration step in auditory processing.

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...”

Researchers engineer light-activated skeletal muscle - MIT News Office

Researchers engineer light-activated skeletal muscle - MIT News Office: The group has genetically engineered muscle cells to flex in response to light, and is using the light-sensitive tissue to build highly articulated robots...
The researchers cultured such cells, or myoblasts, genetically modifying them to express a light-activated protein. The group fused myoblasts into long muscle fibers, then shone 20-millisecond pulses of blue light into the dish. They found that the genetically altered fibers responded in spatially specific ways: Small beams of light shone on just one fiber caused only that fiber to contract, while larger beams covering multiple fibers stimulated all those fibers to contract...

Company Aims to Cure Blindness with Optogenetics

Company Aims to Cure Blindness with Optogenetics: Retrosense is developing a treatment in which other cells in the retina could take the place of the rods and cones, cells which convert light into electrical signals. The company is targeting a group of neurons in the eye called ganglion cells. Normally, ganglion cells don't respond to light. Instead, they act as a conduit for electrical information sent from the retina's rods and cones...
Doctors would inject a non-disease causing virus into a patient's eye. The virus would carry the genetic information needed to produce the light-sensitive channel proteins in the ganglion cells. Normally, rods, cones, and other cells translate light information into a code of neuron-firing patterns that is then transmitted via the ganglion cells into the brain. Since Retrosense's therapy would bypass that information processing, it may require the brain to learn how to interpret the signals.

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.

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.

Researchers find new light-sensing mechanism in neurons

Researchers find new light-sensing mechanism in neurons: For more than 100 years, it had been believed that the phototransduction process was solely based on a chemical derived from vitamin A called retinal. Phototransduction is the conversion of light signals into electrical signals in photoreceptive neurons and underlies both image-forming and non-image-forming light sensing.
In discovering this new light-sensing phototransduction mechanism, the UCI scientists found that phototransduction can also be mediated by a protein called cryptochrome, which uses a B2 vitamin chemical derivative for light sensing. Cryptochromes are blue-light photor

Single Worm Neurons Remotely Controlled with Lasers: Scientific American

Single Worm Neurons Remotely Controlled with Lasers: Scientific American: Leifer and his collaborators genetically engineered the one-millimeter-long nematode worm to make particular cells in its body sensitive to light, a technique called optogenetics, developed in recent years by Stanford University psychiatrist and bioengineer Karl Deisseroth [see Deisseroth's "Controlling the Brain with Light," Scientific American, November 2010]. Because the worm's body is transparent, sharply focused lasers, pointed with an accuracy of 30 microns, could turn on or suppress individual neurons with no need for electrodes or other invasive methods...
Other teams have performed optogenetic studies and controlled individual neurons on immobilized worms. But, to understand the organism's physiology, says Leifer, it is necessary to manipulate it as it swims freely.

Now I See You - Technology Review

Now I See You - Technology Review: "In mammals' eyes, a set of cells in the retina detects light, and then a separate layer of cells, called ganglion cells, relays that information to the brain. Because macular degeneration and other retinal diseases cause the light-detecting cells to die but leave the ganglion cells intact, researchers have been trying for 50 years to decipher their code—the patterns by which the ganglion cells fire—so as to capitalize on the eye's natural circuitry. Nirenberg has now nailed that, or at least a close approximation. After 10 years of work, she knows the relationship between what we see and how that translates into ganglion-cell firing patterns."

Gero Miesenboeck reengineers a brain | Video on TED.com

Gero Miesenboeck reengineers a brain | Video on TED.com: "In the quest to map the brain, many scientists have attempted the incredibly daunting task of recording the activity of each neuron. Gero Miesenboeck works backward -- manipulating specific neurons to figure out exactly what they do, through a series of stunning experiments that reengineer the way fruit flies percieve light."

Stanford-led team validates, extends fMRI research on brain activity

Stanford-led team validates, extends fMRI research on brain activity - “It was often assumed that a positive fMRI BOLD signal can represent increased activity of excitatory neurons, but this was never really known and, in fact, became much more controversial over the years,” said Deisseroth. Now, the new study confirms those earlier assumptions.