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Scientists have been studying human language for centuries, and for good reason.
Our language abilities seem to far exceed those of any other living thing — so understanding
how we communicate is essential to understanding what makes us so powerful spiecies.
Plus, there are lots of people who have specific disabilities with language — what doctors
call aphasias.
And understanding the seat of language in the brain could help doctors better treat
those conditions.
Of course, if you cracked open a Psych 101 textbook before this decade, you might think
we already know what that seat is.
About 150 years ago, scientists identified Broca’s and Wernicke’s areas — the two
main “language centers” in the brain.
They’re often described as the regions responsible for language production and comprehension,
respectively — but at best, that glosses over what these parts actually do.
And lingering misconceptions about them not only impair our understanding of how our brains
work — they also hamper our ability to effectively treat people who struggle to communicate.
Way back in the 1850s, one of the biggest debates in psychology was whether the brain
had specialized regions.
Researchers had recently shown that there was some degree of this — like, that the
brainstem did different stuff than the rest of the brain.
But many thought that within the larger regions, all of the tissue was equally important for
everything — kind of like how there isn’t just one part of your liver that breaks down alcohol.
The research of Pierre Paul Broca and Carl Wernicke played a huge part in changing that.
It all started in 1861 when Broca — a French physician — met a patient named Louis Victor Leborgne.
Though, everyone called him "Tan" because that was the only word he could say.
Before he was 30, he communicated normally.
Then, seemingly out of the blue, it was just “tan”.
He’d usually say it twice — tan tan.
So he was kind of a real life Hodor.
Though, his speech impediment wasn’t from some messed-up magical thing.
And what Broca found really interesting was that it seemed like Tan could still understand
what other people said and retained other intellectual abilities.
So when Tan died, Broca performed an autopsy.
And he noted that a small part of Tan’s brain — a spot in front of the left ear — was damaged.
A few months later, he had another patient with similar language issues — and similar brain damage.
That led Broca to conclude that this region was the part of the brain responsible for
producing speech.
He called it the “center for articulated language,” but it became known as Broca’s area.
Then, about a decade later, Carl Wernicke seemed to discover the part of the brain responsible
for comprehending language.
His patients also struggled to communicate, but in a very different way — they basically
spoke gibberish and couldn’t parse spoken or written language.
They didn’t have damage to Broca’s area.
Instead, their troubles appeared to be caused by damage to a region a bit further back,
where the temporal lobe meets the parietal lobe — what we now call Wernicke’s area.
Broca and Wernicke’s findings together cemented the idea that there were specific regions
for certain brain functions.
And over the past century, the research of these two pioneers has formed the foundation
of the neuroscience of language.
Even today, it’s often said that Broca’s area is where language is produced, while
Wernicke’s is where language is understood.
But that’s just kind of wrong.
Like, Broca’s area doesn’t seem to play a big role in physically producing speech.
Broca got that idea because his patients had such severe language deficits without appearing
to lose the ability to understand what’s said to them.
But it turns out he missed something important when he examined their brains because he didn’t
dissect them to look deeper.
Luckily though, he preserved those brains, so researchers were able to re-examine them
with high-resolution MRI scans in 2007, that’s awesome!
What those scan revealed there was a lot more damage.
And it was likely the damage to areas outside of Broca’s area which caused their severe
and lasting speech deficits.
More recent research on Broca’s area suggests that it’s specialized for one specific part
of language, namely syntax: how words are arranged to form coherent phrases and sentences.
In healthy brains, Broca’s area seems to monitor for syntax errors.
Like, it lights up when people read sentences with poor grammar, but not ones with spelling mistakes.
And damage to this area alone doesn’t seem to permanently impair the ability to speak words.
People with such damage can generally say a few of the words they’re aiming for — they
just struggle to put together a full, complex sentence.
Also, because Broca’s area is involved in syntax, it is involved in language comprehension.
For example, studies have found that stimulating it electrically — and therefore throwing
off the natural firing of neurons — can make it harder for people to understand complex
verbal instructions or what to do when what they’re told clashes with written instructions.
Similarly, it turns out Wernicke’s area isn’t the end-all and be-all of language comprehension.
Wernicke didn’t actually make that claim, mind you.
He proposed that it was specialized for the sounds of language, and that there was another
region where concepts were processed.
And that’s actually not far off.
See, people with damage to Wernicke’s area generally string together nonsense words and
they expect everyone to understand them.
And that’s probably because they mix up sounds.
Now, unless you’re a professional orator, you’ve probably done this at some point.
Like, I’ve probably done this while recording this episode.
Like, “can you mass me the pilk?”
But, you also probably caught yourself as you said it and realized the wrong thing came out.
When this happens, my son points at me and he laughs, and he says “You said the wrong word!”
That same ability runs as kind of a simulator just before you speak to plan the sounds so
they come out right.
And that’s what Wernicke’s area seems to actually do: it processes the sounds of words,
whether the person is listening, reading, or speaking.
That’s why, unlike Broca’s area, Wernicke’s area becomes active when you read spelling
and grammar errors.
And people with damage there often swap in the wrong sounds or even whole words when speaking.
Though, they can’t tell they’re doing it — so they only get upset once other people
seem confused.
It’s not that they can’t understand language.
In fact, the ability to understand the meaning of words seems to have little to do with Wernicke’s area.
Instead, issues with word comprehension are tied to damage that occurs to the front of
the temporal lobe — and in both hemispheres.
But, looking back, it’s hard to blame people for thinking Broca’s and Wernicke’s areas
were the seats of language in the brain.
They didn’t have the techniques we do now for examining brains in living people.
And connecting specific aphasia symptoms to brain damage is tough because patients tend
to have damage to multiple areas and present with a number of overlapping symptoms.
Now, scientists are putting together a more accurate map of the parts of the brain involved in language.
There are still some open questions about how these brain regions work and how they
work with each other and other parts of the brain.
But we know that there’s more to language than these two areas.
The upside to this is that even when there’s damage to these so-called “language centers”,
there may still be therapies that can help.
And ultimately, the more we understand about the neuroscience of language, the closer we’ll
get to effectively treating all sorts of aphasias.
Thanks for watching this episode of SciShow Psych!
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at SciShow can keep making educational psychology videos like this one.
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So thanks for getting all nerdy with us!
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