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Vol. LXVI, No. 13
June 20, 2014
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Digest

Bionic Vision Coming More Into Focus

In laboratory tests, researchers have used electrical stimulation of retinal cells to produce the same patterns of activity that occur when the retina sees a moving object.

In laboratory tests, researchers have used electrical stimulation of retinal cells to produce the same patterns of activity that occur when the retina sees a moving object.

In laboratory tests, researchers have used electrical stimulation of retinal cells to produce the same patterns of activity that occur when the retina sees a moving object. Although more work remains, this is a step toward restoring natural, high-fidelity vision to blind people, the researchers say. The work was funded in part by NIH.

Just 20 years ago, bionic vision was more a science fiction cliché than a realistic medical goal. But in the past few years, the first artificial vision technology has come on the market in the United States and Western Europe, allowing people who’ve been blinded by retinitis pigmentosa to regain some of their sight. While remarkable, the technology has its limits. It has enabled people to navigate through a doorway and even read headline-sized letters, but not to drive, jog down the street or see a loved one’s face.

A team based at Stanford University is working to improve the technology by targeting specific cells in the retina—the neural tissue at the back of the eye that converts light into electrical activity.

“We’ve found that we can reproduce natural patterns of activity in the retina with exquisite precision,” said Dr. E.J. Chichilnisky, a professor of neurosurgery at Stanford. The study was published in Neuron and was funded in part by NEI and NIBIB.

MDMA Can Be Fatal in Warm Environments

A moderate dose of MDMA, commonly known as Ecstasy or Molly, that is typically nonfatal in cool, quiet environments can be lethal in rats exposed to conditions that mimic the hot, crowded, social settings where the drug is often used by people, a study finds. Scientists have identified the therapeutically relevant cooling mechanism to enable effective interventions when faced with MDMA-induced hyperthermia. The study, published June 4 in the Journal of Neuroscience, was conducted by researchers at NIDA.

While MDMA can have a range of adverse health effects, previous studies have shown that high doses of MDMA increase body temperature, while results with moderate doses were inconsistent. This has led some people to assume that the drug is harmless if taken in moderation. However, this study shows that in rats even moderate doses of MDMA in certain environments can be dangerous because it interferes with the body’s ability to regulate temperature.

“We know that high doses of MDMA can sharply increase body temperature to potentially lead to organ failure or even death,” said NIDA director Dr. Nora Volkow. “However, this current study opens the possibility that even moderate doses could be deadly in certain conditions.”

Shining a Light on Memory

Using a flash of light, scientists have inactivated and then reactivated a memory in genetically engineered rats. The study, supported by NIH, is the first cause-and-effect evidence that strengthened connections between neurons are the stuff of memory.

“Our results add to mounting evidence that the brain represents a memory by forming assemblies of neurons with strengthened connections, or synapses,” explained Dr. Roberto Malinow of the University of California, San Diego, an NIMH grantee. “Further, the findings suggest that weakening synapses likely disassembles neuronal assemblies to inactivate a memory.”

Malinow, Dr. Roger Tsien, an NINDS grantee, and other UCSD colleagues reported June 1 in the journal Nature on their findings using cutting-edge optical/gene-based technology.

“Beyond potential applications in disorders of memory deficiency, such as dementia, this improved understanding of how memory works may hold clues to taking control of runaway emotional memories in mental illnesses, such as post-traumatic stress disorder,” said NIMH director Dr. Thomas Insel.

Physical Activity Can Help Maintain Mobility in Older People

A carefully structured, moderate physical activity program can reduce risk of losing the ability to walk without assistance, perhaps the single most important factor in whether vulnerable older people can maintain their independence, a study has found.

Older people who lose their mobility have higher rates of disease, disability and death. Research has shown the benefits of regular physical activity for a variety of populations and health conditions. But none has identified a specific intervention to prevent mobility disability.

In a large clinical study supported by NIH, researchers found that a regular, balanced and moderate physical activity program followed for an average of 2.6 years reduced the risk of major mobility disability by 18 percent in an elderly, vulnerable population.

Results were published online May 27 in the Journal of the American Medical Association.


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