Since its discovery in the 1860’s, Broca’s area has been assumed to be the region of the brain responsible for human speech with responsibilities ranging from language comprehension to actually speaking words. However, a new paper published in the Proceedings of the National Academy of Sciences explains that activity in this area is rather low when an individual is speaking, which goes against conventional wisdom about the function of this region. Having a better understanding of the true breadth of function of this region could be beneficial to developing new treatments for those who suffer brain injuries due to stroke, epilepsy, or head trauma.
"Every year millions of people suffer from stroke, some of which can lead to severe impairments in perceiving and producing language when critical brain areas are damaged," lead author Adeen Flinker said in a press release. "Our results could help us advance language mapping during neurosurgery as well as the assessment of language impairments.”
Broca's area. Image credit: Adeen Flinker
The study utilized the brain scans of seven patients who had been hospitalized due to their epilepsy. They were asked to read words aloud from a piece of paper or repeat what another person had said, and their brain activity was analyzed during this time. While Broca’s area was quite active when the test subjects were reading the words and determining what to say in their heads, as was expected, the moment they began talking, the area curiously became inactive.
It has traditionally been believed that language processing and speech production largely came from Broca’s area (as well as Wernicke's area), which would have remained active during the actual act of speaking. However, this new paper has shown that it is not as straight forward as that.
"That belief drives how we map out language during neurosurgery and classify language impairments," Flinker continued. "This new finding helps us move towards a less dichotomous view where Broca's area is not a center for speech production, but rather a critical area for integrating and coordinating information across other brain regions.”
The function of Broca’s area was first identified when Pierre Paul Broca noticed that those who had suffered strokes or had other brain injuries affecting this particular region of the frontal lobe also had difficulty speaking.
"Broca's area shuts down during the actual delivery of speech, but it may remain active during conversation as part of planning future words and full sentences," Flinker explained.
There is still much to learn about the function of this area, as there have been instances of damage to Broca’s area that did not result in impaired speech. Moving forward, the researchers hope to make better sense of this important region of the brain.