Summary: Stimulating a part of the auditory cortex called the planum temporale improved speech perception, researchers report.
Stimulating a specific part of the auditory cortex immediately improved speech perception over background noise in an epilepsy patient, according to new research in Journal of Neuroscience.
To treat severe cases of epilepsy, surgeons implant electrodes into the patient’s brain to pinpoint the area triggering the seizures.
During one of these procedures, surgeons implanted electrodes near part of the auditory cortex called the planum temporale (PT) that seemed to improve speech perception when stimulated.
Researchers at Columbia University and The Feinstein Institutes for Medical Research put together a set of experiments to explore the exact properties of the region, which had been difficult to study non-invasively.
They stimulated the patient’s PT while playing sound clips of someone talking with extensive background noise — like a noisy party. The patient deciphered the spoken sentence and rated the clarity on a scale from 1 to 5.
Without stimulation, that patient could hear only a few of the words and rated the clips as low as 2. After stimulation, they understood most of the words and rated clips as 4 or 5.
The patient described the experience as, “The voices get a lot clearer. I still hear the noise, but the voice gets a lot clearer, as if someone is saying it in my ear.”
Future research will verify the role of the PT in speech perception in other patients.
About this auditory neuroscience research news
Author: Calli McMurray
Contact: Calli McMurray – SfN
Image: The image is in the public domain
Original Research: Closed access.
“Improved Speech Hearing in Noise with Invasive Electrical Brain Stimulation” by Prachi Patel, Bahar Khalijhinejad, Jose L. Herrero, Stephan Bickel, Ashesh D. Mehta and Nima Mesgarani. Journal of Neuroscience
Improved Speech Hearing in Noise with Invasive Electrical Brain Stimulation
Speech perception in noise is a challenging everyday task with which many listeners have difficulty.
Here, we report a case in which electrical brain stimulation of implanted intracranial electrodes in the left planum temporale (PT) of a neurosurgical patient significantly and reliably improved subjective quality (up to 50%) and objective intelligibility (up to 97%) of speech in noise perception.
Stimulation resulted in a selective enhancement of speech sounds compared with the background noises. The receptive fields of the PT sites whose stimulation improved speech perception were tuned to spectrally broad and rapidly changing sounds.
Corticocortical evoked potential analysis revealed that the PT sites were located between the sites in Heschl’s gyrus and the superior temporal gyrus. Moreover, the discriminability of speech from nonspeech sounds increased in population neural responses from Heschl’s gyrus to the PT to the superior temporal gyrus sites.
These findings causally implicate the PT in background noise suppression and may point to a novel potential neuroprosthetic solution to assist in the challenging task of speech perception in noise.