Briefs | February 2014 Hearing Review

Musical Brain-reading Sheds Light on Neural Processing of Music MATLAB Handle Graphics

Finnish and Danish researchers have developed a new method that performs decoding, or brain-reading, during continuous listening to real music. Based on recorded brain responses, the method predicts how certain features related to tone color and rhythm of the music change over time, and recognizes which piece of music is being listened to. It also allows pinpointing the areas in the brain that are most crucial for the processing of music.

Using functional magnetic resonance imaging, a research team at the Finnish Centre of Excellence in Interdisciplinary Music Research at the Universities of Jyväskylä and Helsinki, and the Center for Functionally Integrative Neuroscience in Aarhus University, Denmark, recorded the brain responses of participants while they were listening to a 16-minute excerpt of the album Abbey Road by the Beatles.

Afterwards, they used computational algorithms to extract a collection of musical features from the recording. Subsequently, they employed a collection of machine-learning methods to train a computer model that predicts how the features of the music change over time. Finally, they developed a classifier that predicts which part of the music the participant was listening to at each time.

The researchers found that most of the musical features included in the study could be reliably predicted from the brain data. They also found that the piece being listened to could be predicted significantly better than chance.

Brain areas contributing to the decoding of pulse clarity in music. High activity in red areas predicts clear pulse, high activity in blue areas unclear pulse. Adapted from the Universities of Jyväskylä and Helsinki press release.

Tinnitus Findings at U-M/Kresge Open New Treatment Avenues Tinnitus

Researchers in the University of Michigan Medical School have reported new scientific findings that help explain what is going on in the “unquiet brains” of people who have tinnitus. The discovery reportedly reveals an important new target for treating the condition. The team already has a patent pending and a device in development based on the approach. The work provides a science-based, novel approach to treating tinnitus in humans, according to the university.

Susan Shore, PhD, U-M Kresge Hearing Research Institute, and senior author of the paper, explains they have confirmed that a process called stimulus-timing dependent multisensory plasticity is altered in animals with tinnitus—and that this plasticity is “exquisitely sensitive” to the timing of signals coming into a key area of the brain.

That area, called the dorsal cochlear nucleus, is the first station for signals arriving in the brain from the ear via the auditory nerve. But it is also a center where “multitasking” neurons integrate other sensory signals, such as touch, together with the hearing information.

Shore explains that in tinnitus, some of the input to the brain from the ear’s cochlea is reduced, while signals from the somatosensory nerves of the face and neck, related to touch, are excessively amplified. “It’s as if the signals are compensating for the lost auditory input, but they overcompensate and end up making everything noisy.”

The new findings illuminate the relationship between tinnitus, hearing loss, and sensory input and help explain why many tinnitus sufferers can change the volume and pitch of their tinnitus’s sound by clenching their jaw, or moving their head and neck.

Fifty million people in the United States and millions more worldwide have the condition, according to the American Tinnitus Association.

The critical findings are published online in the December 11, 2013 edition of the Journal of Neuroscience.

Study Helps Explain Why Some Ear and Respiratory Infections Become Chronic

EarInfectionScientists have figured out how a bacterium that causes ear and respiratory illnesses is able to elude immune detection in the middle ear, likely contributing to chronic or recurrent infections in adults and children. A team from The Research Institute at Nationwide Children’s Hospital in Columbus, Ohio, received a $1.6 million grant from the National Institutes of Health (NIH) to further the work.

Led by Kevin M. Mason, PhD, and Sheryl S. Justice, PhD, principal investigators in the Center for Microbial Pathogenesis, the effort is offering new information about nontypeable Haemophilus influenzae (NTHI). Contrary to what its name suggests, NTHI does not cause the flu; it is, however, the culprit behind most childhood cases of otitis media, or chronic ear infections. NTHI also can cause sinusitis, pneumonia, and a range of other upper and lower respiratory illnesses.

Humans are the only known hosts for H. influenzae bacteria, a family comprised of many different strains, the most well-known of which is type b, or Hib. Once the leading cause of bacterial meningitis in children under age 5, Hib is largely under control today and NTHI is responsible for the majority of invasive H. influenzae infections in all age groups.

At any given time, NTHI is present in the nose and mouth in about 50% of young children, an environment rich in nutrients such as heme-iron, which all bacteria need to survive. It isn’t until NTHI moves into the lungs and middle ear that the bacterium causes most problems.

“Our data support a paradox, wherein mechanisms that are thought to clear the bacteria at these sites actually may be promoting increased survival of bacteria and contributing to disease severity,” says Mason, who also is an assistant professor of pediatrics at the Ohio State University College of Medicine.

Specifically, the scientists figured out how NTHI uses the body’s own immune response to its advantage. At the first sign of bacterial attack in the lungs, middle ear, and certain other parts of the body, the immune system blocks access to nutrients bacteria need to survive—including heme-iron—a process called nutritional immunity. This initial immune response gives way to a series of other defensive maneuvers to fight the infection, including inflammation, which involves the release of chemicals that are supposed to isolate the invading bacterium and direct white blood cells to the site of infection.

By devising a lab experiment that mimicked the body’s immune response to NTHI infection in the middle ear, the scientists were able to observe how the bacterium responds to this onslaught. They found that the serum that carries disease-fighting chemicals and white blood cells to the site of infection also includes heme-iron. When NTHI was re-exposed to heme-iron, it underwent structural changes that allowed it to divide much more slowly and become elongated and spaghetti-like in appearance. Because white blood cells typically target the rapidly dividing shorter cells, they ignored NTHI, leaving the bacterium to grow and thrive.

The findings are published in the October 10 edition of PLOS Pathogens.

Music Brings Memories Back to the Brain Injured Billboard

In the first study of its kind, researchers have used popular music to help severely brain-injured patients recall personal memories. Amee Baird, PhD, and Séverine Samson, PhD, recently outlined the results and conclusions of their pioneering research in the journal Neuropsychological Rehabilitation.

It is the very first study to examine “music-evoked autobiographical memories” (MEAMs) in patients with acquired brain injuries (ABIs), rather than those who are healthy or suffer from Alzheimer’s disease.

In the study, extracts from “Billboard Hot 100” number-one songs in random order were played to five patients. The songs, taken from the whole of the patient’s lifespan from age 5, were also played to five control subjects with no brain injury. All were asked to record how familiar they were with a given song, whether they liked it, and what memories it invoked.

They found that the frequency of recorded MEAMs was similar for patients (38%–71%) and controls (48%–71%). Only one of the four ABI patients recorded no MEAMs. In fact, the highest number of MEAMs in the whole group was recorded by one of the ABI patients. In all those studied, the majority of MEAMs were of a person, people, or a life period and were typically positive. Songs that evoked a memory were noted as more familiar and more liked than those that did not.

Original citation for this article: Research roundup. Hearing Review. 2014;21(2): 52-54.