For as long as 150 years, scientists knew that Broca’s area was critical in transforming thoughts into words. Only recently did the exact function and role of Broca’s area become known.
The Broca area is located in the inferior frontal gyrus, the part of the brain known as the motor speech area. The area is responsible for speech production, including regulating breathing while speaking and vocalizing. It’s also linked to language processing and comprehension.
Using brain mapping techniques, researchers have successfully tracked the flow of speech through the brain and found that Broca’s area is most active just before words are spoken. But what other interesting facts does this area contain?
Broca’s Area Structure And Location
There are many definitions for Broca’s area, some of which aren’t consistent. Still, it is generally believed that the Broca area lies in the third frontal convolution of the brain.
It’s located anterior to the motor cortex above the Sylvian fissure on the precentral gyrus.
It comprises two areas known as the pars triangularis (Brodmann area 45) and pars opercularis (Brodmann area 44), located in the posterior inferior frontal gyrus of the dominant hemisphere. (Radiopaedia)
This position is, however, still hotly debated amongst many researchers in the field of Neurology.
Most individuals are thought to have Broca’s area in the left cerebral hemisphere.
In contrast, the corresponding area in the right hemisphere is present – it is simply not thought to play a vital role in speech production. (Neuroscientifically Challenged)
The Broca area’s arterial supply lies in the superior division of the middle cerebral artery or the MCA.
The Broca area is connected to other parts of the brain, including Wernicke’s area, which is a region of the brain that contains motor neurons involved in speech comprehension.
Besides speech production, Broca’s area is also involved in the comprehension of language – specifically regarding motor-related activities like hand movements – as well as sensorimotor learning and integration. (Britannica)
Damage to this area can result in a speech disorder known as Broca aphasia.
Aphasia results from an individual losing the ability to understand speech or communicate using sign language, often through cranial trauma or related medical conditions.
There are several types of aphasia. The two main ones for this article are Wernicke’s aphasia, also known as fluent aphasia (video example).
Then there is Broca’s aphasia, or non-fluent aphasia (video example).
Broca’s aphasia, also known as expressive aphasia, is characterized by the loss of the ability to produce language but still maintain comprehension. (Healthline)
Damage to the Broca’s area is challenging, but so are the related aphasias. The National Aphasia Association website provides information, support, and opportunities for those wanting to learn more about aphasia or support the cause.
How Broca’s Aphasia Occurs
A neurological condition that damages cells in the language processing area of the brain result in aphasia.
When brain cells are deprived of oxygen long enough, that area of the brain stops working.
Often, the cause cannot be controlled and includes incidents such as:
- Brain tumor/s
- Head injuries
- Infections in the brain
- Progressive neurological conditions like Alzheimer’s disease
A person with Broca’s aphasia needs speech therapy and cannot expect the condition to improve by itself. (Healthline)
Speech therapy involves the individual working closely with a speech-pathologist to practice speaking in a safe environment.
Individuals with Broca’s aphasia can improve their impairment by going to support groups, book clubs, or social settings with people experiencing the same (or similar) condition.
They can also accelerate their progress by speaking to people they trust and who can give them the correct cues to communicate.
Broca’s Area Function
Since the discovery of Broca’s area, scientists and researchers have become more knowledgeable in understanding conditions that affect language production.
Individuals who present with damage to the Broca’s area are likely to present with symptoms relating to:
- Difficulties in formulating speech and written word
- Producing repetitive speech
- Speaking in non-coherent sentences
These occur as a result of brain lateralization.
What is Brain Lateralization?
Physician Paul Broca was one of the earlier advocates for the idea of lateralization of brain function.
Brain lateralization is the view that specific brain regions perform brain functions.
Prior to the idea of brain lateralization, many accepted that humans used the whole brain for every action and function performed by a person.
For this reason, many earlier researchers believed that every region of the brain produced language rather than being centralized.
Broca provided strong evidence for brain lateralization in his research.
He specifically provided evidence for the claim that language functioning is located in the dominant brain hemisphere (the left hemisphere in most people).
With their modern neuroimaging techniques, researchers can now focus on activity within Broca’s area to understand it more clearly.
One can also find the difference in the structure and function of the area in other conditions that affect language processes.
One example is a study by Bauman and Kemper in 2005 that suggested that language differences in individuals with Autism may correlate to differences in their Broca area.
While the importance of Broca’s area in language production is still up for debate, much of the collected evidence is through seeing what is impaired in individuals with language processing difficulties.
Because of this, there is still uncertainty over what specific language function is lost due to damage. (Simply Psychology)
Some studies suggest that Broca’s area plays a role in motor movements required for speech production, while others think it involves verbal working memory and grammar.
Other Specialized Language Areas
The brain is a complex system; language comprehension and expression are one of the more complicated processes.
Broca and Wernicke’s areas are located primarily in the brain’s left hemisphere.
Wernicke’s area is located close to the auditory cortex and is associated with language comprehension through signals from related sensory association areas.
Wernicke’s area is vital to personality since it is how sensory information is received and understood. It also accesses auditory and visual memories, which are events and perceptions that allow a difference in people.
On the other hand, Broca’s area is known as the motor speech area and is located close to the motor cortex, which controls motor actions.
The motor cortex triggers movement-specific signals, which are transmitted through the spinal cord and motor neurons into the muscles.
Because Broca’s area is so close to the motor cortex, it coordinates muscle activity related to the larynx, pharynx, cheeks, lips, jaw, and tongue.
Often when a person experiences traumatic injury to Broca’s area, they can make sounds, but words are limited and often not present.
Another area important for language processing is the receptive speech area, also known as the auditory association area.
This area utilizes feedback to adjust motor commons from the motor speech area.
A multitude of speech-related problems can occur if any of the specific sensory areas are damaged.
Most of the time, people with an impaired Wernicke’s area will be able to speak fluently, while people with an impaired Broca’s area experience non-fluent or broken language use.
The Wernicke’s and Broca’s areas are connected to one another via the arcuate fasciculus’s neuronal tract.
The arcuate fasciculus is a bundle of white matter containing long and short fibers connecting the frontal, parietal, and temporal lobes.
This tract acts as the main pathway from Broca’s area in the frontal lobe and Wernicke’s area in the temporal lobe.
The tract also has a functional role in syntax or word order within language.
Researchers believe that Wernicke’s area comprehends language and selects the appropriate response. The response is then sent through the arcuate fasciculus, which arrives at Broca’s area to be articulated.
Some people with injuries to this part of the brain struggle to form words and speak but can comprehend words spoken to them. Others can speak consistently but use many incorrect words. (Science Direct)
It’s important to note that Broca and Wernicke’s areas are the main language centers, but without other areas of the brain, they cannot coordinate reading, speaking, and writing.
The History Behind Broca’s Area
In 1861, French physician Paul Broca founded the Broca’s Area by studying patients who had language impairments.
He contributed significant research into understanding how humans produce speech, and almost 150 years later, researchers are still looking into this area.
At the age of 30, Louis Victor Leborgne lost his ability to produce recognizable speech patterns – the only syllable he could produce was ‘Tan.’ Upon his admission into a suburban Parisian mental hospital, Bicêtre, Leborgne was unable to speak for three odd months. (Scientific American)
Leborgne suffered immense epileptic seizures for years before his admittance. He continued to have these seizures and so remained one of Broca’s patients until his death 21 years later.
In Broca’s autopsy, he found a neurosyphilitic lesion on the surface of Leborgne’s left frontal lobe.
Another patient of Broca’s by the name of Lelong exhibited reduced productive speech. Upon admission, he could only utter five distinct words: ‘yes,’ ‘no,’ ‘three,’ ‘always,’ and ‘Lelo’ (a mispronunciation of his own name).
After his death, Broca conducted an autopsy in which he found a similar lesion in the lateral frontal lobe. This discovery pioneered the belief that speech was localized to that particular area.
Current Research Into Broca’s Area
In 2007, a study was published where Paul Broca’s two most notable patients’ brains were reinspected using high-resolution volumetric MRI.
This study aimed to take three-dimensional scans of the brains of Leborgne and Lelong (Paul Broca’s patients) to identify the extent of cortical and subcortical lesions more clearly.
The study also attempted to locate the lesion sites in the frontal lobe and see their relation to the area now known as Broca’s area.
What the researchers found was interesting.
The MRI imaging suggested that areas other than Broca’s area may have contributed to the patients’ reduced productive speech.
This finding is important because it means that lesions in Broca’s area alone can possibly cause temporary speech disruption – but do not result in severe speech arrest. (Wikipedia)
They also found that the region which was considered vital for language production by Paul Broca is not the exact region known as Broca’s area.
Their study supported the claim that language and cognition result from multiple brain regions rather than one localized area. (Weill Institute for Neurosciences)
While this study is not the most recent, it is one of the most significant in attempting to understand Broca’s research. It contributes important knowledge to the vastly unknown functions of the brain.
One study conducted in 2021 details Broca Area’s clinical significance, while others have looked into the neural architecture of language.
Cooke and fellow researchers found that using fMRI scans (functional magnetic resonance imaging) on participants.
At the same time, they were presented with written sentences differing in grammatical structure and short-term memory demands that there was significant activation in the area corresponding to Broca’s area.
Another study by Gabrieli and fellow researchers found that Broca’s area is activated during tasks that do not require actual speech.
A study that used PET scans (positron emission tomography) also found that there was an increased blood flow in the Broca area when participants read silently versus reading aloud.
This finding suggests that Broca’s area could be more important in semantic processing for silent reading than reading aloud.
Otherwise, a study by Bookheimer showed that there is increased activation in Broca’s area when people learn grammatical rules, reproduce rhymes, and discern between speech sounds.
This area is also thought to become more active during movement and action, as well as during the imitation of movement.
Broca’s area is also thought to contain mirror neurons.
Mirror neurons are a type of brain cell that respond equally when we perform an action and when we watch someone else performing the same action and then mirroring their performance.
Why it’s significant in research concerning Broca’s area is that it could suggest that the area is important in observing others’ movements during speech and imitating those speech-movement patterns.
The human is one of the most complex organisms, which means that a lot of research is still being conducted, especially regarding the brain and the processing of language.
The Broca area is only one of the regions in the brain believed to aid language processing.
It works by interacting with the flow of sensory information and creating a pathway for passing that information to the temporal cortex, where it can be spoken.
Sometimes, people experience trauma to this area of the brain, which can result in impaired language production.