Engineering a Photo-Switch for Nerve Cells in the Eye and Brain

Chemists and vision scientists at the University of Illinois at Chicago have designed a light-sensitive molecule that can stimulate a neural response in cells of the retina and brain — a possible first step to overcoming degenerative eye diseases like age-related macular degeneration, or to quieting epileptic seizures.

Their results are reported online in the journal Nature Communications.

Macular degeneration, the leading cause of vision loss in people over 50, is caused by loss of light-sensitive cells in the retina — the rods and cones.

"The rods and cones, which absorb light and initiate visual signals, are the broken link in the chain, even though what we call the ‘inner cells’ of the retina, in many cases, are still potentially capable of function," says David Pepperberg, professor of ophthalmology and visual sciences in the UIC College of Medicine, the principal investigator on the study.

"Our approach is to bypass the lost rods and cones, by making the inner cells responsive to light."

Pepperberg and his colleagues are trying to develop light-sensitive molecules that — when injected into the eye — can find their way to inner retinal cells, attach themselves, and initiate the signal that is sent to the brain.

Study links exposure to light at night to depression, learning issues

For most of history, humans rose with the sun and slept when it set. Enter Thomas Edison, and with a flick of a switch, night became day, enabling us to work, play, and post cat and kid photos on Facebook into the wee hours.

However, according to a new study led by a Johns Hopkins biologist, this typical 21st- century scenario comes at a serious cost: When people routinely burn the midnight oil, they risk suffering depression and learning issues, and not only because of lack of sleep. The culprit could also be exposure to bright light at night from lamps, computers, and even iPads.

"Basically, what we found is that chronic exposure to bright light—even the kind of light you experience in your own living room at home or in the workplace at night if you are a shift worker—elevates levels of a certain stress hormone in the body, which results in depression and lowers cognitive function,” said Samer Hattar, a biology professor in the Krieger School of Arts and Sciences.

The study, published in the Nov. 14 Advance Online Publication of the journal Nature, used mice to demonstrate how special cells in the eye (called intrinsically photosensitive retinal ganglion cells, or ipRGCs) are activated by bright light, affecting the brain’s center for mood, memory, and learning.

How Cells in the Nose Detect Odors

Now a team of scientists, led by neurobiologists at the University of California, Riverside, has an explanation. Focusing on the olfactory receptor for detecting carbon dioxide in Drosophila (fruit fly), the researchers identified a large multi-protein complex in olfactory neurons, called MMB/dREAM, that plays a major role in selecting the carbon dioxide receptors to be expressed in appropriate neurons.

Study results appear in the Nov. 15 issue of Genes & Development.  The research is featured on the cover of the issue.

According to the researchers, a molecular mechanism first blocks the expression of most olfactory receptor genes (~60) in the fly’s antennae. This mechanism, which acts like a brake, relies on repressive histones —proteins that tightly wrap DNA around them. All insects and mammals are equipped with this mechanism, which keeps the large families of olfactory receptor genes repressed.

“How, then, do you release this brake so that only the carbon dioxide receptor is expressed in the carbon dioxide neuron while the remaining receptors are repressed?” said Anandasankar Ray, an assistant professor of entomology, whose lab conducted the research. “Our lab, in collaboration with a lab at Stanford University, has found that the MMB/dREAM multi-protein complex can act on the genes of the carbon dioxide receptors and de-repress the braking mechanism — akin to taking the foot off the brake pedal. This allows these neurons to express the receptors and respond to carbon dioxide.”

Ray explained that one way to understand the mechanism in operation is to consider a typewriter. When none of the keys are pressed, a spring mechanism or “brake” can be imagined to hold the type bars away from the paper. When a key is pressed, however, the brake on that key is overcome and the appropriate letter is typed onto the paper. And just as typing only one letter in one spot is important for each letter to be recognized, expressing one receptor in one neuron lets different sensor types to be generated in the nose.

Bonobos Catch Yawns from Friends

For bonobos, yawning is contagious, but only between friends.

Yawns spread more easily between family and close friends, and from high-status monkeys to those lower on the totem pole, according to a study published online in the journal PLoS ONE. This pattern of social yawning mimics one found in humans and suggests infectious yawning is a byproduct of empathy, which coordinates emotions in a group.

"It underlines that the mechanism of yawn contagion in the two species is the same," said study co-author Elisabetta Palagi, a primate researcher at the University of Pisa in Italy. "One of the possible functions of yawn contagion is to synchronize individuals of a social group. In humans, yawn contagion is extremely important but just between people who share strong bonds."

Brain waves make waves

Naturally, our brain activity waxes and wanes. When listening, this oscillation synchronizes to the sounds we are hearing. Researchers at the Max Planck Institute for Human Cognitive and Brain Sciences have found that this influences the way we listen. Hearing abilities also oscillate and depend on the exact timing of one’s brain rhythms. This discovery that sound, brain, and behaviour are so intimately coupled will help us to learn more about listening abilities in hearing loss.

Fantasy-Reality Confusion a Primary Cause of Childhood Nighttime Fears

From monsters under the bed to bogeymen in the closet, most children experience nighttime fears at some point in their development. And while most grow out of them without any professional intervention, others contend with persistent and extended periods of these fears, with a risk of developing anxiety problems later in life.

As part of a large-scale project on nighttime fears funded by the Israeli Science Foundation, Prof. Avi Sadeh of Tel Aviv University’s School of Psychological Sciences is exploring how these fears fit into the normal developmental process — and when they become a problem. Together with Dr. Jonathan Kushnir, who completed his Ph.D. studies in the field in Prof. Sadeh’s lab, MA student Tamar Zisenwine, and Ph.D. student Michal Kaplan, he discovered that a child’s ability to differentiate fact from fiction has a huge impact on overcoming terror of things that go bump in the night.

In their study, published in Child Psychiatry and Human Development, the researchers found that preschoolers with persistent nighttime fears were far less able to distinguish reality from fantasy compared to their peers. The research will help clinicians and parents alike to develop interventions that can better soothe fretful children, he says, noting that a strong imagination can ultimately be used to the child’s psychological advantage.

Watch A French Researcher Control A Robot With His Brain

Researchers in Japan are using a brain-machine interface to control the actions of a humanoid robot. The goal is to allow people “to feel embodied in the body of a humanoid robot,” in the words of one researcher.

Roboticists at the CRNS-AIST Joint Robotics Laboratory, a collaboration between the French National Center for Scientific Research and the Japanese Institute of Advanced Industrial Science and Technology, are trying to interpret brain waves into actions that can be understood by a robot. In the video, a volunteer wears an electrode cap and watches a screen with flashing dots, which is used to teach his brain to associate flickering objects with actions. By focusing his attention, he can induce actions, which are translated from his brain activity into robotic motion.

A signal processing unit on a computer translates his brain activity and classifies it into a series of tasks. Then the team can instruct the robot on which task to perform. It could help paraplegics who can’t perform certain tasks on their own. Or it could be used for crazyfuture tourism, says Abderrahmane Kheddar, director of the JRL: “A paraplegic patient in Rome would be able to pilot a humanoid robot for sightseeing in Japan.”

Human Eye Gives Researchers Visionary Design for New, More Natural Lens Technology

Drawing heavily upon nature for inspiration, a team of researchers has created a new artificial lens that is nearly identical to the natural lens of the human eye. This innovative lens, which is made up of thousands of nanoscale polymer layers, may one day provide a more natural performance in implantable lenses to replace damaged or diseased human eye lenses, as well as consumer vision products; it also may lead to superior ground and aerial surveillance technology.

This work, which the Case Western Reserve University, Rose-Hulman Institute of Technology, U.S. Naval Research Laboratory, and PolymerPlus team describes in the Optical Society’s (OSA) open-access journal Optics Express, also provides a new material approach for fabricating synthetic polymer lenses.

The fundamental technology behind this new lens is called “GRIN” or gradient refractive index optics. In GRIN, light gets bent, or refracted, by varying degrees as it passes through a lens or other transparent material. This is in contrast to traditional lenses, like those found in optical telescopes and microscopes, which use their surface shape or single index of refraction to bend light one way or another.

“The human eye is a GRIN lens,” said Michael Ponting, polymer scientist and president of PolymerPlus, an Ohio-based Case Western Reserve spinoff launched in 2010. “As light passes from the front of the human eye lens to the back, light rays are refracted by varying degrees. It’s a very efficient means of controlling the pathway of light without relying on complicated optics, and one that we attempted to mimic.”