Brain News – A study provides insight into how auditory feedback influences the fluency of speech. It seeks to further examine the brain’s feedback mechanisms involved in speaking the intended words or pronunciations.
A study reveals the links between a brain region and fluency in speech. The study was conducted by researchers at NYU Grossman School of Medicine and NYU Langone Health.
The study observed 15 epilepsy patients in two sessions: a word reading session and a sentence reading session. Their direct cortical recordings were recorded using electrocorticography (ECoG), with a delayed auditory feedback (DAF) paradigm. The visual stimuli were presented on a laptop screen and the participants were asked to read them aloud. The auditory stimuli were presented through earphones. Each participant’s voice was recorded using an external microphone. An individually recorded voice was delayed at 4 different amounts (no delay, 50, 100, and 200 milliseconds) to mimic real-life slurring of speech. This was played back to the respective participant through earphones.
The findings, published in PLOS Biology, provide insight into how auditory feedback influences the motor control of speech.
During speech production, the brain displays a behavior termed as “auditory feedback control of speech”. The brain generates auditory feedback and makes an internal estimate of the speech intended to be made. It monitors and adjusts the speech to maintain fluency. The brain also registers the difference between this internal estimate and the auditory feedback in reality. In case that happens, an error signal is relayed to vocal motor regions. This causes the correction of speech in reality, so as to produce the intended speech.
The study delved into the subregions of the cerebral cortex to understand their roles in real-time speech feedback. Amongst these, the researchers claim, the dorsal precentral gyrus plays the most significant role. It corrects the errors in delayed auditory feedback and ensures that the intended words were used or pronounced correctly.
The study further seeks to understand the dorsal precentral gyrus’s feedback mechanisms for ‘correcting’ pronunciation. The researchers wish to explain how it generates the brain’s initial memory of the intended pronunciation and—noticing errors in how the words were actually spoken—seeks to execute the initially intended pronunciation.
The researchers are enthusiastic that such precise research about the role of the dorsal precentral gyrus in speech-correction bodes well for advances in medical treatments.
“It may be possible to focus treatments on [the dorsal precentral gyrus] for such conditions as stuttering and Parkinson’s disease, which both involve problems with delayed speech processing in the brain,” says Adeen Flinker, study senior investigator and neuroscientist.
To Know More You May Refer To
Ozker, M., Doyle, W., Devinsky, O., & Flinker, A. (2022). A cortical network processes auditory error signals during human speech production to maintain fluency. PLoS biology, 20(2), e3001493. https://doi.org/10.1371/journal.pbio.3001493
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