Featured Research

from universities, journals, and other organizations

Our brains are wired so we can better hear ourselves speak

Date:
December 9, 2010
Source:
University of California - Berkeley
Summary:
Like the mute button on the TV remote control, our brains filter out unwanted noise so we can focus on what we're listening to. But when it comes to following our own speech, a new brain study shows that instead of one homogeneous mute button, we have a network of volume settings that can selectively silence and amplify the sounds we make and hear.

Activity in the auditory cortex when we speak and listen is amplified in some regions of the brain and muted in others. In this image, the black line represents muting activity when we speak.
Credit: Courtesy of Adeen Flinker

Like the mute button on the TV remote control, our brains filter out unwanted noise so we can focus on what we're listening to. But when it comes to following our own speech, a new brain study from the University of California, Berkeley, shows that instead of one homogenous mute button, we have a network of volume settings that can selectively silence and amplify the sounds we make and hear.

Related Articles


Neuroscientists from UC Berkeley, UCSF and Johns Hopkins University tracked the electrical signals emitted from the brains of hospitalized epilepsy patients. They discovered that neurons in one part of the patients' hearing mechanism were dimmed when they talked, while neurons in other parts lit up.

Their findings, published Dec. 8, 2010 in the Journal of Neuroscience, offer new clues about how we hear ourselves above the noise of our surroundings and monitor what we say. Previous studies have shown a selective auditory system in monkeys that can amplify their self-produced mating, food and danger alert calls, but until this latest study, it was not clear how the human auditory system is wired.

"We used to think that the human auditory system is mostly suppressed during speech, but we found closely knit patches of cortex with very different sensitivities to our own speech that paint a more complicated picture," said Adeen Flinker, a doctoral student in neuroscience at UC Berkeley and lead author of the study.

"We found evidence of millions of neurons firing together every time you hear a sound right next to millions of neurons ignoring external sounds but firing together every time you speak," Flinker added. "Such a mosaic of responses could play an important role in how we are able to distinguish our own speech from that of others."

While the study doesn't specifically address why humans need to track their own speech so closely, Flinker theorizes that, among other things, tracking our own speech is important for language development, monitoring what we say and adjusting to various noise environments.

"Whether it's learning a new language or talking to friends in a noisy bar, we need to hear what we say and change our speech dynamically according to our needs and environment," Flinker said.

He noted that people with schizophrenia have trouble distinguishing their own internal voices from the voices of others, suggesting that they may lack this selective auditory mechanism. The findings may be helpful in better understanding some aspects of auditory hallucinations, he said.

Moreover, with the finding of sub-regions of brain cells each tasked with a different volume control job -- and located just a few millimeters apart -- the results pave the way for a more detailed mapping of the auditory cortex to guide brain surgery.

In addition to Flinker, the study's authors are Robert Knight, director of the Helen Wills Neuroscience Institute at UC Berkeley; neurosurgeons Edward Chang, Nicholas Barbaro and neurologist Heidi Kirsch of the University of California, San Francisco; and Nathan Crone, a neurologist at Johns Hopkins University in Maryland.

The auditory cortex is a region of the brain's temporal lobe that deals with sound. In hearing, the human ear converts vibrations into electrical signals that are sent to relay stations in the brain's auditory cortex where they are refined and processed. Language is mostly processed in the left hemisphere of the brain.

In the study, researchers examined the electrical activity in the healthy brain tissue of patients who were being treated for seizures. The patients had volunteered to help out in the experiment during lulls in their treatment, as electrodes had already been implanted over their auditory cortices to track the focal points of their seizures.

Researchers instructed the patients to perform such tasks as repeating words and vowels they heard, and recorded the activity. In comparing the activity of electrical signals discharged during speaking and hearing, they found that some regions of the auditory cortex showed less activity during speech, while others showed the same or higher levels.

"This shows that our brain has a complex sensitivity to our own speech that helps us distinguish between our vocalizations and those of others, and makes sure that what we say is actually what we meant to say," Flinker said.


Story Source:

The above story is based on materials provided by University of California - Berkeley. The original article was written by Yasmin Anwar. Note: Materials may be edited for content and length.


Journal Reference:

  1. A. Flinker, E. F. Chang, H. E. Kirsch, N. M. Barbaro, N. E. Crone, R. T. Knight. Single-Trial Speech Suppression of Auditory Cortex Activity in Humans. Journal of Neuroscience, 2010; 30 (49): 16643 DOI: 10.1523/JNEUROSCI.1809-10.2010

Cite This Page:

University of California - Berkeley. "Our brains are wired so we can better hear ourselves speak." ScienceDaily. ScienceDaily, 9 December 2010. <www.sciencedaily.com/releases/2010/12/101209101515.htm>.
University of California - Berkeley. (2010, December 9). Our brains are wired so we can better hear ourselves speak. ScienceDaily. Retrieved April 1, 2015 from www.sciencedaily.com/releases/2010/12/101209101515.htm
University of California - Berkeley. "Our brains are wired so we can better hear ourselves speak." ScienceDaily. www.sciencedaily.com/releases/2010/12/101209101515.htm (accessed April 1, 2015).

Share This


More From ScienceDaily



More Mind & Brain News

Wednesday, April 1, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

AAA: Distracted Driving a Serious Teen Problem

AAA: Distracted Driving a Serious Teen Problem

AP (Mar. 25, 2015) While distracted driving is not a new problem for teens, new research from the AAA Foundation for Traffic Safety says it&apos;s much more serious than previously thought. (March 25) Video provided by AP
Powered by NewsLook.com
Smartphone Use Changing Our Brain and Thumb Interaction, Say Researchers

Smartphone Use Changing Our Brain and Thumb Interaction, Say Researchers

Reuters - Innovations Video Online (Mar. 25, 2015) European researchers say our smartphone use offers scientists an ideal testing ground for human brain plasticity. Dr Ako Ghosh&apos;s team discovered that the brains and thumbs of smartphone users interact differently from those who use old-fashioned handsets. Jim Drury went to meet him. Video provided by Reuters
Powered by NewsLook.com
Many Don't Know They Have Alzheimer's, But Their Doctors Do

Many Don't Know They Have Alzheimer's, But Their Doctors Do

Newsy (Mar. 24, 2015) According to a new study by the Alzheimer&apos;s Association, more than half of those who have the degenerative brain disease aren&apos;t told by their doctors. Video provided by Newsy
Powered by NewsLook.com
A Quick 45-Minute Nap Can Improve Your Memory

A Quick 45-Minute Nap Can Improve Your Memory

Newsy (Mar. 23, 2015) Researchers found those who napped for 45 minutes to an hour before being tested on information recalled it five times better than those who didn&apos;t. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins