Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Tune-deaf people may hear a sour note unconsciously

11.06.2008
Findings could help scientists study consciousness

People with tune deafness aren't able to tell when a musician accidentally strikes the wrong note in a song, but their brains know the difference. Researchers from the National Institute on Deafness and Other Communication Disorders (NIDCD), part of the National Institutes of Health, have found that people with tune deafness, an auditory processing disorder in which a person with normal hearing has trouble distinguishing notes in a melody, are able to detect a wrong note unconsciously. The study is published in the June 11, 2008, issue of the online journal PLoS ONE (http://www.plosone.org/doi/pone.0002349).

Because tune deafness is a commonly occurring phenomenon that is largely inherited, the study of this disorder could enable scientists to use the tools of genetic research to better understand the differences between conscious and unconscious thought.

Neuroscientists have long been baffled by what separates the state of consciousness from unconsciousness. Other sensory disorders have been identified in which the brain perceives a stimulus outside of conscious awareness. However, because these disorders are typically caused by damage to the brain, there is an inconsistency in data from one patient to the next and researchers have difficulty finding a sufficient number of volunteer patients for clinical trials.

"The prevalence of tune deafness is surprisingly high—perhaps as much as 2 percent of the population is tune deaf—and it exists in an otherwise normal, uninjured brain," said James F. Battey, Jr., M.D., Ph.D., director of the NIDCD. "These factors, combined with the fact that tune deafness is largely genetic in origin, now raises the possibility of using tune deafness as a new way to study consciousness."

A person who is tune deaf is unable to perceive pitch, reproduce melodies, or identify deviations in a melody. According to geneticist Dennis Drayna, Ph.D., one of the study authors, not only is music not enjoyable for people with tune deafness, many of them don't fully understand what music is. "For severely affected tune-deaf people, Yankee Doodle is no different than traffic noise in Manhattan. It's fairly meaningless to them," he said.

Dr. Drayna worked closely with neuroimaging scientist Allen Braun, M.D., and others in NIDCD's Division of Intramural Research to randomly screen 1,218 individuals using an online version of the Distorted Tunes Test. The Distorted Tunes Test is a standardized survey that tests a person's ability to identify whether or not a short melody is played correctly. (The online version, which was created by Dr. Drayna, can be found on the NIDCD Web site: http://www.nidcd.nih.gov/tunetest/.) The researchers then selected those volunteers who scored in the bottom 10 percent, screened them for hearing loss and other factors, and arrived at seven subjects with severe tune deafness who were otherwise medically normal and were willing to take part in the study. Ten healthy control subjects who performed normally on the Distorted Tunes Test also took part in the study.

Dr. Braun, Joseph McArdle, Ph.D., and others then used electroencephalography (EEG), a brain imaging technique that places electrodes around a person's head and measures the electrical impulses of millions of neurons in the brain, to study these subjects further. The researchers measured the volunteers' responses as they listened to an altered version of the Distorted Tunes Test in which the incorrect melodies had a single wrong note at the end. Volunteers listened to 102 familiar melodies, roughly half of which were correct, and half of which contained the errant last note. The researchers then sifted through the EEG data to isolate the brain's response to a specific stimulus—in this case, the right or wrong note.

Of principal interest were two signals that brains normally generate when they are presented with a stimulus that doesn't match what the brain expects to hear, such as the wrong note in a song. The first, the mismatch negativity (MMN), is a large negative signal that occurs roughly 200 milliseconds after the unexpected stimulus is heard; the second signal, the P300, is a large positive signal occurring roughly 300 milliseconds after the unexpected stimulus.

Because tune-deaf people consistently don't recognize when a wrong note is played or sung, the researchers hypothesized that their brains would not generate the MMN or P300 signals, and as expected, this was true for the MMN signal. However, in the case of the P300 signal, tune-deaf volunteers were processing the wrong note in the same way as the normal participants, even though they weren't consciously aware of the deviation. Other brain signals demonstrated that correct notes were being processed equally well for both tune-deaf and normal volunteers.

As for how a brain can register a wrong note without the person being aware of it, the researchers explain that the MMN and P300 signals are generated in different parts of the brain. The MMN is generated near the primary auditory cortex, in the brain's temporal lobe, while the P300 is generated in the frontoparietal cortex, downstream from the auditory cortex. Normal brains process sounds in a series, with the frontal and parietal cortices receiving signals that have already been processed in the auditory cortex. In someone with tune deafness, however, the direct route for processing the wrong note may be disrupted, and signals are possibly being routed to the two regions through parallel pathways independent of each other. In this way, information about a wrong note may not be reaching the auditory cortex at all, while information reaching the frontoparietal cortex is not consciously perceived.

The researchers hope to conduct studies to better pinpoint the locations from which the MMN and P300 signals originate in the brain. In addition, the researchers will continue to pursue genetic studies on the causes of tune deafness which, if found, could help them and others grapple with the very puzzling notion of consciousness at the cellular and molecular level.

Jennifer Wenger | EurekAlert!
Further information:
http://www.nih.gov
http://www.nidcd.nih.gov
http://www.nih.gov

More articles from Studies and Analyses:

nachricht Win-win strategies for climate and food security
02.10.2017 | International Institute for Applied Systems Analysis (IIASA)

nachricht The personality factor: How to foster the sharing of research data
06.09.2017 | ZBW – Leibniz-Informationszentrum Wirtschaft

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Electrode materials from the microwave oven

19.10.2017 | Materials Sciences

New material for digital memories of the future

19.10.2017 | Materials Sciences

Physics boosts artificial intelligence methods

19.10.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>