Tinnitus affects processing of emotions

Patients with persistent ringing in the ears – a condition known as tinnitus – process emotions differently in the brain from those with normal hearing, researchers report in the journal Brain Research.

Tinnitus afflicts 50 million people in the United States, according to the American Tinnitus Association, and causes those with the condition to hear noises that aren’t really there. These phantom sounds are not speech, but rather whooshing noises, train whistles, cricket noises or whines. Their severity often varies day to day.

University of Illinois speech and hearing science professor Fatima Husain, who led the study, said previous studies showed that tinnitus is associated with increased stress, anxiety, irritability and depression, all of which are affiliated with the brain’s emotional processing systems.

“Obviously, when you hear annoying noises constantly that you can’t control, it may affect your emotional processing systems,” Husain said. “But when I looked at experimental work done on tinnitus and emotional processing, especially brain imaging work, there hadn’t been much research published.”

She decided to use functional magnetic resonance imaging (fMRI) brain scans to better understand how tinnitus affects the brain’s ability to process emotions. These scans show the areas of the brain that are active in response to stimulation, based upon blood flow to those areas.

Three groups of participants were used in the study: people with mild-to-moderate hearing loss and mild tinnitus; people with mild-to-moderate hearing loss without tinnitus; and a control group of age-matched people without hearing loss or tinnitus. Each person was put in an fMRI machine and listened to a standardized set of 30 pleasant, 30 unpleasant and 30 emotionally neutral sounds (for example, a baby laughing, a woman screaming and a water bottle opening). The participants pressed a button to categorize each sound as pleasant, unpleasant or neutral.

The tinnitus and normal-hearing groups responded more quickly to emotion-inducing sounds than to neutral sounds, while patients with hearing loss had a similar response time to each category of sound. Over all, the tinnitus group’s reaction times were slower than the reaction times of those with normal hearing.

Activity in the amygdala, a brain region associated with emotional processing, was lower in the tinnitus and hearing-loss patients than in people with normal hearing. Tinnitus patients also showed more activity than normal-hearing people in two other brain regions associated with emotion, the parahippocampus and the insula. The findings surprised Husain.

“We thought that because people with tinnitus constantly hear a bothersome, unpleasant stimulus, they would have an even higher amount of activity in the amygdala when hearing these sounds, but it was lesser,” she said. “Because they’ve had to adjust to the sound, some plasticity in the brain has occurred. They have had to reduce this amygdala activity and reroute it to other parts of the brain because the amygdala cannot be active all the time due to this annoying sound.”

Because of the sheer number of people who suffer from tinnitus in the United States, a group that includes many combat veterans, Husain hopes her group’s future research will be able to increase tinnitus patients’ quality of life.

“It’s a communication issue and a quality-of-life issue,” she said. “We want to know how we can get better in the clinical realm. Audiologists and clinicians are aware that tinnitus affects emotional aspects, too, and we want to make them aware that these effects are occurring so they can better help their patients.”

http://www.medicalnewstoday.com/releases/278846.php

Picture courtesy of tinnitusart.com

 

 

 

Cochlear implants without external hardware? New chip looks promising

 

Cochlear implants – devices that help people who would otherwise be deaf have some limited hearing – currently require hardware mounted on the outside of the skull to accommodate a recharger and microphone. Now, researchers in the US have developed a new low-powered chip that offers the prospect of eliminating these bulky, visible externals.

The new chip is the work of engineers in the Microsystems Technology Laboratory at Massachusetts Institute of Technology (MIT) together with team members from Harvard Medical School and the Massachusetts Eye and Ear Infirmary.

They are presenting a paper about their work at the 2014 IEEE international Solid-State Circuits Conference being held in San Francisco, CA, this week.

Cochlear implants are used by hundreds of thousands of people worldwide whose hearing is impaired because sensory hair cells in their cochleas, within the inner ear, do not pass on sound vibrations to the brain.

In the US, around 70,000 people have them, many of them children. The device works by electrically stimulating the auditory nerve to receive sound signals that pass from an external microphone into the ear.

Current designs mean that users have to wear a 1-inch diameter disk-shaped transmitter on the skull, attached by a wire to a microphone and power source inside what looks like a large hearing aid around the ear.

But the new low-powered signal-processing chip could lead to a new implant design that eliminates the need for any external hardware, say the researchers. The implant could be wirelessly charged – it could run for about 8 hours between charges – and instead of an external microphone, it could pick up sound using the natural microphone chamber of the inner ear, which is often intact in implant users.

One of the researchers, Anantha Chandrakasan, a professor of electrical engineering at MIT, says:

“The idea with this design is that you could use a phone, with an adaptor, to charge the cochlear implant, so you don’t have to be plugged in. Or you could imagine a smart pillow, so you charge overnight, and the next day, it just functions.”

Lawrence Lustig, director of the Cochlear Implant Center at the University of California at San Francisco (UCSF), who describes the device as “very cool,” says people often experience more stigma with hearing loss than vision loss, so “people would be very keen on losing the externals for that reason alone.”

And, he says, there would also be practical benefits, such as “not having to take it off when you’re near water or worrying about components getting lost or broken or stolen.”

Design is based on middle-ear implant mechanism

The researchers based their new design on the mechanism of a middle-ear implant. The idea is to pick up the sound vibrations in the delicate bones of the middle ear and instead of conveying them to the cochlea, send them to a microchip implanted in the ear that converts them to electrical signals passed to an electrode in the cochlea.

Lowering the power requirements of the chip was the key to eliminating the need for the external skull-mounted hardware, say the researchers.

The device has been tested on patients already with cochlear implants to check it does not affect ability to hear. And the researchers showed the chip can pick up and process speech played into the middle ear.

Lustig says such a device would require more complex surgery to implant than existing designs. A current operation takes about an hour – the new design would probably need about 3 to 4 hours of surgery but would still be a relatively straightforward procedure.

“I don’t anticipate putting a lot of extra risk into the procedure,” he adds.

Medical News Today recently reported a study that showed short stays in darkness can boost hearing. Another US team working with mice found that preventing sight for as little as a week was enough to help the brain process sound more effectively.

http://www.medicalnewstoday.com/articles/272439.php

Picture courtesy to wikipedia