A particular resonance pattern in the brain’s auditory processing region appears to be key to its ability to discriminate speech, researchers have found. They found that the inherent rhythm of neural activity called “theta band” specifically reacts to spoken sentences by changing its phase.
The researchers also noted that the natural oscillation of this frequency provides further evidence that the brain samples speech segments about the length of a syllable.
The findings represent the first time that such a broad neural response has been identified as central to perceiving the highly complex dynamics of human speech, said the researchers. Previous studies have explored the responses of individual neurons to speech sounds, but not the response of the auditory cortex as a whole.
In their experiments, the researchers asked volunteers to listen to spoken sentences such as “He held his arms close to his sides and made himself as small as possible.” At the same time, the subjects’ brains were scanned using magnetoencephalography. In this imaging technique, sensitive detectors are used to measure the magnetic fields produced by electrical activity in brain regions.
Poeppel and Luo pinpointed the theta band—which oscillates between four and eight cycles per second—as one that changed its phase pattern with unique sensitivity and specificity in response to the spoken sentences. What’s more, as the researchers degraded the intelligibility of the sentences, the theta band pattern lost its tracking resonance with the speech.
The researchers said their findings suggest that the brain discriminates speech by modulating the phase of the continuously generated theta wave in response to the incoming speech signal. What’s more, they said, the time-dependent characteristics of this theta wave suggest that the brain samples the incoming speech in “chunks” that are about the length of a syllable from any given language.
The researchers include Huan Luo and David Poeppel of the University of Maryland College Park in College Park, MD. This work is supported by NIH R01 DC05660 to D.P.
Luo et al.: “Phase Patterns of Neuronal Responses Reliably Discriminate Speech in Human Auditory Cortex.” Neuron 54, 1001–1010, June 21, 2007. DOI 10.1016/j.neuron.2007.06.004.
- PHYSICAL SCIENCES
- EARTH SCIENCES
- LIFE SCIENCES
- SOCIAL SCIENCES
Subscribe to the newsletter
Stay in touch with the scientific world!
Know Science And Want To Write?
- Bang !! 13 TeV - The Highest Energy Ever Achieved By Mankind ?!
- Mystery Of Morgellons - Disease Or Delusion - Scientific Hypothesis Of Connection With Lyme Disease
- Highest Energy Collisions ? Not In My Book
- WISE J224607.57-052635.0, The Most Luminous Galaxy In The Universe
- Blue Buffalo Admits Its Pet Food Contains The Poultry Byproduct It Ridicules In Competitors
- Tanzania's Disappearing Serengeti
- Tunable Liquid Metal Antenna Controlled By Voltage
- "Thanks, glad to have helped. And wonderful to hear that your symptoms are so much improved :)...."
- "Myth#3A:Australia borders both in the Western Pacific AND the Indian Ocean. We call a typhoon a..."
- "Okay for what she says about BDD, see her paper here: Association of spirochetal infection..."
- "Bovine Digital Dermatitis was connected to morgellons disease because of wart-like and hair-like..."
- "FINALLY, a supportive article that reviews the facts and is not afraid to put it out in a positive..."
- Vaccines developed for H5N1, H7N9 avian influenza strains
- European Medicines Agency recommends full approval of ibrutinib to treat Waldenstrom's Macroglobulinemia
- In Northern Ireland, sectarianism has become sextarianism
- RegeneRx Phase II Dry Eye Trial results
- How schizophrenia risk gene DISC1 affects the brain