New Worlds: Eyeing retina repair

Scientists are now designing a variety of medical devices to counter the effects of retinal disorders by sending visual signals to the brain.

Lab technician using microscope (photo credit: INGIMAGE / ASAP)
Lab technician using microscope
(photo credit: INGIMAGE / ASAP)
Israeli and British scientists have developed a new, light-sensitive film that could eventually form the basis of a prosthetic retina to help people suffering from retinal damage or degeneration. Hebrew University and Tel Aviv University researchers with colleagues from Newcastle University produced the research, which was recently published in the journal Nano Letters.
The retina – a the thin layer of tissue on the inner surface of the eye that is composed of light-sensitive nerve cells – converts images to electrical impulses and sends them to the brain. Damage to the retina from macular degeneration, retinitis pigmentosa and other eye diseases can reduce vision or cause total blindness. In the US alone, age-related macular degeneration (AMD) affects more than 15 million Americans, and over 200,000 new cases are diagnosed every year.
Scientists are now designing a variety of medical devices to counter the effects of retinal disorders by sending visual signals to the brain. But these silicon-chip based solutions are typically hampered by their size, use of rigid parts or requirement of external wiring such as to energy sources.
In the new study, HU researchers headed by Prof. Uri Banin and his graduate student Nir Waiskopf of the chemistry institute and the Center for Nanoscience and Nanotechnology worked with TAU and Newcastle University colleagues to develop a novel approach for retina stimulation. Their device absorbs light and stimulates neurons without using wires or external power sources.
The researchers combined semiconductor nanorods and carbon nanotubes to create a wireless, light-sensitive, flexible implantable film. The film transforms visual cues to electric signals, mimicking the function of the photo-sensitive cells in the retina. Thus it could potentially form part of a future prosthetic device that will replace the damaged cells in the retina. The researchers tested the new device on light-insensitive retinas from embryonic chicks and observed a neuronal response triggered by light.
The new device is compact, capable of higher resolution than previous designs and more effective at stimulating neurons. While much work remains until this can provide a practical solution, with additional research the researchers hope their carbon nanotube-semiconductor nanocrystal film will one day effectively replace damaged retinas in humans.
It was quite well known that the late British prime minister Margaret Thatcher went through extensive voice coaching to exude a more authoritative, powerful persona.
Now, research published in Psychological Science, a journal of the Association for Psychological Science, shows that being in a position of power can fundamentally change the way you speak, altering basic acoustic properties of the voice. Other people are able to pick up on these vocal cues to know who is really in charge, according to new research published.
“We tend to focus on our words when we want to come across as powerful to others, but these findings suggest that basic acoustic cues also play an important role,” said psychological scientist and lead researcher Sei Jin Ko of San Diego State University. “Our findings suggest that whether it’s parents attempting to assert authority over unruly children, haggling between a car salesman and customer, or negotiations between heads of states, the sound of the voices involved may profoundly determine the outcome of those interactions.”
The researchers had long been interested in non-language- related properties of speech, but it was Thatcher that inspired them to investigate the relationship between acoustic cues and power.
“We wanted to explore how something so fundamental as power might elicit changes in the way a voice sounds, and how these situational vocal changes impact the way listeners perceive and behave toward the speakers,” said Ko.
In the first experiment, they recorded 161 college students reading a passage aloud; this first recording captured baseline acoustics. The participants were then randomly assigned them to play a specific role in an ensuing negotiation exercise. Students assigned to a “high” rank were told to go into the negotiation imagining that they either had a strong alternative offer, valuable inside information, or high status in the workplace or they were asked to recall an experience in which they had power before the negotiation started. Low-rank students, on the other hand, were told to imagine they had either a weak offer, no inside information or low workplace status, or they were asked to recall an experience in which they lacked power.
The students then read a second passage aloud as if they were leading off negotiations with their imaginary adversary, and their voices were recorded. Everyone read the same opening, allowing the researchers to examine acoustics while holding the speech content constant across all participants.
Comparing the first and second recordings, the researchers found that the voices of students assigned to high-power roles tended to go up in pitch and become more monotone (less variable in pitch) and more variable in volume than the voices of students assigned low-power roles.
“Amazingly, power affected our participants’ voices in almost the exact same way that Thatcher’s voice changed after her vocal training,” the researchers said.
The students’ vocal cues also didn’t go unnoticed. A second experiment with a separate group of college students revealed that listeners who had no knowledge of the first experiment were able to pick up on these power-related vocal cues to determine who did and did not have power.
Listeners ranked speakers who had been assigned to the high-rank group as more likely to engage in high-power behaviors, and they were able to categorize whether a speaker had high or low rank with considerable accuracy.
In line with the vocal changes observed in the first experiments, listeners tended to associate higher pitch and voices that varied in volume with high-power behaviors. They also associated louder voices with higher status.
“These findings suggest that listeners are quite perceptive to these subtle variations in vocal cues and they use these cues to decide who is in charge,” they concluded.