Featured Research

from universities, journals, and other organizations

Mapping The Selective Brain

Date:
November 24, 2007
Source:
Cell Press
Summary:
Researchers have added a new piece to the puzzle of how the brain selectively amplifies those distinctions that matter most from the continuous cascade of sights, sounds, and other sensory input. Whether recognizing a glowering face among smiling ones or the unmistakable sound of a spouse calling one's name, such "categorical perception" is central to sensory function.

Researchers have added a new piece to the puzzle of how the brain selectively amplifies those distinctions that matter most from the continuous cascade of sights, sounds, and other sensory input. Whether recognizing a glowering face among smiling ones or the unmistakable sound of a spouse calling one's name, such "categorical perception" is central to sensory function.

Specifically, Rajeev Raizada and Russell Poldrack report identifying a brain region that selectively amplifies behaviorally significant speech sounds. They also emphasized that their experimental approach represents a useful advance because it not only detects brain activity associated with a given task, but identifies the type of computation the brain is performing during the task.

In new experiments, researchers used a set of ten computer-synthesized speech sounds that represented a continuum from the sound "ba" to the sound "da." They designated these on a 1 to 10 scale, with the former being pure "ba" and the latter being pure "da."

The researchers first played human volunteers different pairs of the two sounds, for example 4 and 7, and asked them to indicate which pairs they distinguished as different from one another.

They next played the same pairs of sounds to the subjects as the subjects' brains were scanned using functional magnetic resonance imaging (fMRI). This widely used technique involves using harmless radio waves and magnetic fields to measure blood flow in brain regions, which reflects activity.

By searching for brain areas distinctively activated during pairs of sounds the subjects perceived as different, the researchers could pinpoint any brain region involved in the selective amplification of categorical perception.

The fMRI scans revealed a sensory processing area of the brain known as the left supramarginal gyrus as a distinctive categorical processing area. This area activated when subjects heard sound pairs that they had earlier reported perceiving as different. In contrast, the left supramarginal gyrus did not respond significantly to sound pairs that the subjects perceived as the same, found the researchers.

What's more, lower-level auditory regions of the brain or another speech-processing area did not respond significantly to the distinctive sound pairs, found the researchers.

The researchers wrote that "A key aspect of the method proposed here, and one that is especially relevant to categorical perception, is that we were seeking not just neural amplification per se, but in particular selective amplification. Thus, an area such as the left supramarginal gyrus not only amplified differences between the phonetic stimuli, but moreover it specifically amplified only the differences that corresponded to crossing each subject's perceptual category boundary.

"The way in which the brain selectively amplifies stimulus differences can help to reveal how its representations of the world are structured," they wrote. "Such amplification can be said to be involved in a neural representation, as opposed to being just incidental activity, only if it is related to perception and behavior.... Used together, these tools can help to reveal when the brain sees the world in shades of gray, and when it sees in black-and-white."

The researchers reported their findings in the November 21, 2007, issue of the journal Neuron.

The researchers include Rajeev D.S. Raizada, of the Institute for Learning and Brain Sciences, University of Washington, Seattle, WA, USA; and Russell A. Poldrack, of the UCLA Department of Psychology, Department of Psychiatry and Biobehavioral Sciences, and Brain Research Institute, Los Angeles, CA, USA


Story Source:

The above story is based on materials provided by Cell Press. Note: Materials may be edited for content and length.


Cite This Page:

Cell Press. "Mapping The Selective Brain." ScienceDaily. ScienceDaily, 24 November 2007. <www.sciencedaily.com/releases/2007/11/071121145022.htm>.
Cell Press. (2007, November 24). Mapping The Selective Brain. ScienceDaily. Retrieved October 20, 2014 from www.sciencedaily.com/releases/2007/11/071121145022.htm
Cell Press. "Mapping The Selective Brain." ScienceDaily. www.sciencedaily.com/releases/2007/11/071121145022.htm (accessed October 20, 2014).

Share This



More Mind & Brain News

Monday, October 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Your Birth Season Might Determine Your Temperament

Your Birth Season Might Determine Your Temperament

Newsy (Oct. 20, 2014) A new study says the season you're born in can determine your temperament — and one season has a surprising outcome. Video provided by Newsy
Powered by NewsLook.com
Court Ruling Means Kids' Online Activity Could Be On Parents

Court Ruling Means Kids' Online Activity Could Be On Parents

Newsy (Oct. 17, 2014) In a ruling attorneys for both sides agreed was a first of its kind, a Georgia appeals court said parents can be held liable for what kids put online. Video provided by Newsy
Powered by NewsLook.com
The Best Foods To Boost Your Mood

The Best Foods To Boost Your Mood

Buzz60 (Oct. 17, 2014) Feeling down? Reach for the refrigerator, not the medicine cabinet! TC Newman (@PurpleTCNewman) shares some of the best foods to boost your mood. Video provided by Buzz60
Powered by NewsLook.com
You Can Get Addicted To Google Glass, Apparently

You Can Get Addicted To Google Glass, Apparently

Newsy (Oct. 15, 2014) Researchers claim they’ve diagnosed the first example of the disorder in a 31-year-old U.S. Navy serviceman. 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