Cerebral Cortex Found Responsible for Speech to Ensure People Say The Right Words

A new study recently focused on the half-dozen sub-regions of the surface layer of the brain, also called the cerebral cortex, as they are known to regulate how people move their mouth, lips, and tongue to form words and to play a role in processing what they hear they, themselves are saying.

According to a EurekAlert! report, a region that crosses the "folded surface of the top of the brain," known as the dorsal precentral gyrus, plays a vital role in how people are using the sound of their voices to regulate how they want such words to sound.

The researchers said the ability to take signals from one's voice while talking has long been recognized as vital to fluent speech.

Also recognized is the ability of every person to make possible near-immediate adaptations based on such cues, like slowing down speech to better articulate words that are multi-syllable or" raising the voice to overcome loud background noise."

Identifying Feedback Errors for Speech Slurring

The study, published in PLOS Biology, is led by researchers at NYU Grossman School of medicine. In this research, it was specified that the exact role of each sub-region in real-time speech feedback remained unclear until now, partly because of the difficulty in directly accessing the brain for research while humans are alive and talking.

Results of this new investigation showed that while three cortical regions were mainly involved in correcting speech errors, including the superior temporal gyrus and supramarginal gyrus, only one, specifically the dorsal precentral gyrus, dominated the speech delays, meant to indicate feedback errors, were maximized.

Such brief feedback delays ranged from zero milliseconds to more than 200 milliseconds and were designed to emulate real-life speech slurring.

According to neuroscientist Adeen Flinker, Ph.D., the study senior investigator, their study confirms for the first time the crucial role of the dorsal precentral gyrus in maintaining control over speech "as we are talking," and to guarantee that the words are pronounced as they are wanted to be pronounced.

Precentral Gyrus' Role in How Spoken Words Should Sound

Flinker explained the team is planning further study into the feedback mechanisms of the brain for controlling speech.

The team seeks to explain, in particular, whether the dorsal precentral gyrus, as detailed in an NCBI report, is accountable for generating the initial memory of the brain for how spoken words should sound and noticing any errors in how such words were uttered after the so-called "base signal" is turned into the movements of the muscles needed to form words.

The study senior investigator also said now that "we believe we know" the exact role of the dorsal precentral gyrus in controlling for errors in speech, it may be probable to focus treatments on this brain's region for such conditions as shuttering and Parkinson's disease, both involving problems with delayed speech processing in the brain.

For this research, the study authors examined thousands of recording from upwards of 200 electrodes placed in each brain of the 15 epileptic people already scheduled to go through routine surgery to pinpoint the source of their seizures.

All of the patients, mostly males, and females in their 30s and 40s, were recorded in 2020 at NYU Langone, which funded the study.

Related information about how the brain controls speech is shown on BBC Studios' YouTube video below:

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