An area of the brain called Heschl’s gyrus — long known for handling early auditory processing — plays a far greater role in interpreting speech than previously understood. It helps interpret the meaning behind subtle changes in pitch, tone, and emphasis into meaningful information, according to a recent study published in the journal Nature Communications.
Scientists had long thought that deciphering those qualities — collectively known as prosody — happened in the superior temporal gyrus, an area of the brain associated with speech perception. But experiments that monitored epileptic patients’ brains now challenge those assumptions.
Understanding Speech Perception
A rare set of circumstances led to the discovery. As part of treatment for severe epilepsy, 11 adolescent patients had electrodes implanted deep into the part of the brain that is critical for key language function. The surgeries and experiments took place at the University of Pittsburgh School of Medicine. It represented a close collaboration between neurosurgeons and neuroscientists.
Communication and linguistics research typically rely on recordings from skin surfaces. That method is minimally invasive — but also not very precise.
While patients listened to an audiobook version of “Alice in Wonderland,” scientists monitored activity in multiple regions of their brains. The recordings mapped subtle changes in the reader’s voice to Heschl’s gyrus. Different parts of the brain reacted to the sounds that made up words.
“The results redefine our understanding of the architecture of speech perception,” Barath Chandrasekaran, a Northwestern University scientist and an author of the paper, said in a press release. “We’ve spent a few decades researching the nuances of how speech is abstracted in the brain, but this is the first study to investigate how subtle variations in pitch that also communicate meaning is processed in the brain.”
Read More: 5 Thought-Provoking Facts About Brain Function
Implications for AI
The research also showed that the rise and fall of speech is encoded much earlier in auditory processing than previously thought. Similar research conducted on non-human primates found that those brains could not process these abstract meanings, even though they listened to the same recordings.
The discovery of the role Heschl’s gyrus plays in processing speech holds implications in several fields. This understanding could aide speech rehabilitation, make AI-powered assistants more perceptive, as well as foster a better understanding of what makes human communication unique.
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Before joining Discover Magazine, Paul Smaglik spent over 20 years as a science journalist, specializing in U.S. life science policy and global scientific career issues. He began his career in newspapers, but switched to scientific magazines. His work has appeared in publications including Science News, Science, Nature, and Scientific American.
