What part of the brain controls slurred speech?
Speech impairment in adults
Speech and language impairment may be any of several problems that make it difficult to communicate.
The following are common speech and language disorders.
Aphasia is loss of the ability to understand or express spoken or written language. It commonly occurs after strokes or traumatic brain injuries. It can also occur in people with brain tumors or degenerative diseases that affect the language areas of the brain. This term does not apply to children who have never developed communication skills. There are many different types of aphasia.
In some cases of aphasia, the problem eventually corrects itself, but in others, it doesn’t get better.
With dysarthria, the person has problems expressing certain sounds or words. They have poorly pronounced speech (such as slurring) and the rhythm or speed of speech is changed. Usually, a nerve or brain disorder has made it difficult to control the tongue, lips, larynx, or vocal cords, which make speech.
Dysarthria, which is difficulty pronouncing words, is sometimes confused with aphasia, which is difficulty producing language. They have different causes.
People with dysarthria may also have problems swallowing.
Anything that changes the shape of the vocal cords or the way they work will cause a voice disturbance. Lump-like growths such as nodules, polyps, cysts, papillomas, granulomas, and cancers can be to blame. These changes cause the voice to sound different from the way it normally sounds.
Some of these disorders develop gradually, but anyone can develop a speech and language impairment suddenly, usually due to a stroke or trauma.
- Alzheimer disease
- Brain tumor (more common in aphasia than dysarthria)
- Head trauma
- Transient ischemic attack (TIA)
- Alcohol intoxication
- Diseases that affect nerves and muscles (neuromuscular diseases), such as amyotrophic lateral sclerosis (ALS or Lou Gehrig disease), cerebral palsy, myasthenia gravis, or multiple sclerosis (MS)
- Facial trauma
- Facial weakness, such as Bell’s palsy or tongue weakness
- Head trauma
- Head and neck cancer surgery
- Nervous system (neurological) disorders that affect the brain, such as Parkinson disease or Huntington disease (more common in dysarthria than aphasia)
- Poorly fitting dentures
- Side effects of medicines that act on the central nervous system, such as narcotics, phenytoin, or carbamazepine
- Transient ischemic attack (TIA)
- Growths or nodules on the vocal cords
- People who use their voice heavily (teachers, coaches, vocal performers) are more likely to develop voice disorders.
For dysarthria, ways to help improve communication include speaking slowly and using hand gestures. Family and friends need to provide plenty of time for those with the disorder to express themselves. Typing on an electronic device or using pen and paper can also help with communication.
For aphasia, family members may need to provide frequent orientation reminders, such as the day of the week. Disorientation and confusion often occur with aphasia.Using nonverbal ways of communicating may also help.
It’s important to maintain a relaxed, calm environment and keep external stimuli to a minimum.
- Speak in a normal tone of voice (this condition is not a hearing or emotional problem).
- Use simple phrases to avoid misunderstandings.
- Don’t assume that the person understands.
- Provide communication aids, if possible, depending on the person and condition.
Mental health counseling may help with depression or frustration that many people with speech impairment have.
When to Contact a Medical Professional
Contact the provider if:
- Impairment or loss of communication comes on suddenly
- There is any unexplained impairment of speech or written language
What to Expect at Your Office Visit
Unless the problems have developed after an emergency event, the provider will take a medical history and perform a physical exam. The medical history may require the assistance of family or friends.
The provider will likely ask about the speech impairment. Questions may include when the problem developed, whether there was an injury, and what medicines the person takes.
Diagnostic tests that may be performed include the following:
- Blood tests
- Cerebral angiography to check blood flow in the brain
- CT or MRI scan of the head to check for problems such as tumor
- Electroencephalogram (EEG) to measure electrical activity of the brain
- Electromyography (EMG) to check the health of the muscles and the nerves that control the muscles
- Lumbar puncture to check the cerebrospinal fluid that surrounds the brain and spinal cord
- Urine tests
- X-rays of the skull
If the tests find other medical problems, other specialist doctors will need to be consulted.
For help with the speech problem, a speech and language therapist or social worker will likely need to be consulted.
Language impairment; Impairment of speech; Inability to speak; Aphasia; Dysarthria; Slurred speech; Dysphonia voice disorders
Kirshner HS. Dysarthria and apraxia of speech. In: Jankovic J, Mazziotta JC, Pomeroy SL, Newman NJ, eds. Bradley and Daroff’s Neurology in Clinical Practice. 8th ed. Philadelphia, PA: Elsevier; 2022:chap 14.
Kirshner HS, Wilson SM. Aphasia and aphasic syndromes. In: Jankovic J, Mazziotta JC, Pomeroy SL, Newman NJ, eds. Bradley and Daroff’s Neurology in Clinical Practice. 8th ed. Philadelphia, PA: Elsevier; 2022:chap 13.
Rossi RP, Kortte JH, Palmer JB. Speech and language disorders. In: Frontera WR, Silver JK, Rizzo TD Jr, eds. Essentials of Physical Medicine and Rehabilitation. 4th ed. Philadelphia, PA: Elsevier; 2019:chap 155.
Review Date 5/2/2022
Updated by: Amit M. Shelat, DO, FACP, FAAN, Attending Neurologist and Assistant Professor of Clinical Neurology, Renaissance School of Medicine at Stony Brook University, Stony Brook, NY. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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We’ve Found The Part of The Brain That Helps Us Say Words How We Intend to
While it might feel as though we do it without thinking, getting words from our brain and out of our mouths in an intelligible way is actually an incredibly complex process – and scientists just made a new discovery about a key part of it.
Our brains are always adjusting what we’re saying based on what we’re hearing, such as when we raise our voices in a loud environment. When problems with this feedback system happen, it can lead to disorders including stuttering, autism, Parkinson’s disease, and schizophrenia, among others.
New research has identified the part of the brain that makes sure our words are being properly articulated: the dorsal precentral gyrus. This knowledge could help treat speech problems and neural disorders in the future, the researchers say.
The dorsal precentral gyrus is highlighted in red. (NYU Grossman School of Medicine)
«Our study confirms for the first time the critical role of the dorsal precentral gyrus in maintaining control over speech as we are talking and to ensure that we are pronouncing our words as we want to,» says neuroscientist Adeen Flinker from New York University.
While it was already known that the section of the brain called the cerebral cortex was responsible for controlling the movement of the mouth, lips, and tongue to form words, the details of how this worked hadn’t yet been fully established.
In the new study, researchers enlisted the help of 15 people with epilepsy who were already scheduled to have surgery to look at the cause of their seizures. This surgery involved fitting 200 electrodes to their brain, making them useful subjects to study.
During planned breaks in the surgery, the patients were asked to say aloud words and short sentences. While they read, the participants could hear what they were saying through headphones.
During the experiment, the playback was delayed by 50 milliseconds, 100 milliseconds, 200 milliseconds, or not at all. This technique, Delayed Auditory Feedback (DAF), has been used for decades to mimic slurred speech as a way of analyzing how the brain adapts.
Thousands of recordings were made in total, enabling the researchers to spot differences in neural activity as the delay increased and the study volunteers compensated, slowing down their speech rhythms to match, as you might do with an echo on a video call.
«Human speech production is strongly influenced by the auditory feedback it generates,» write the researchers in their published paper. «When we speak, we continuously monitor our vocal output and adjust our vocalization to maintain fluency.»
Normally, the brain can’t be readily accessed while people are conscious and talking, which is why there are gaps in our knowledge about which part of the brain handles which part of speech control.
The study showed that the superior temporal gyrus and the supramarginal gyrus were involved in correcting errors in speech – both brain regions have been implicated in aphasia, the inability to understand or produce language.
However, the dorsal precentral gyrus was dominant in terms of activity when the delays were introduced, suggesting this part of the brain is behind our vocal self-monitoring.
Now further research is planned into these feedback mechanisms. One potential avenue for study is whether or not the dorsal precentral gyrus is responsible for knowing how spoken words are supposed to sound, and how the pronunciation might differ.
«Now that we believe we know the precise role of the dorsal precentral gyrus in controlling for errors in speech, it may be possible to focus treatments on this region of the brain for such conditions as stuttering and Parkinson’s disease, which both involve problems with delayed speech processing in the brain,» says Flinker.
The research has been published in PLOS Biology.
What Part of the Brain Controls Speech?
What part of the brain controls speech? We participate in communication daily but we rarely stop to think about what part of our brain is responsible.
Have you ever wondered how our minds form words? Or how you understand what other people are saying?
The answer to these questions lies in understanding what part of the brain controls speech.
What Part of the Brain Controls Speech?
The part of the brain which is responsible for speech is called the Broca’s area. It is located in the cerebrum on the left side of the brain. You’ll find it in the frontal lobe. Damage in Broca’s area is characterized by slurred and unclear words. This condition is called Broca’s aphasia or non-fluent aphasia.
Sufferers are able to understand what is being said, they know what they want to say, but the order from the brain to the speech organs cannot be executed.
Speaking is a complex process, as it involves both speech comprehension and speech production. Healthy brains do both effortlessly.
Damage to any area involved in speech can cause various conditions such as dyslexia (not able to read), anomia (not being able to name things), and agraphia (not being able to write).
What Side of the Brain Controls Speech?
The left side of the brain controls speech.
As well as the Broco’s area, another area that controls speech is called the Wernicke’s area. It deals with understanding speech and language. That is how we can understand others and react with proper emotion. It is also connected to the sensory cortex.
People who have damaged this speech center are not able to understand what they hear. However, they do not have problems with word formation. This condition is called Wernicke’s aphasia.
People with damage to both areas have a condition called global aphasia.
Where Is the Speech Center of the Brain?
The entire cerebral cortex contains two hemispheres. They are, for the most part, symmetrical in function. The cerebellum also contains two hemispheres and is located at the back of the brain, the part of the brain responsible for our sense of balance.
For a majority of the population, the speech center of the brain is located in the left hemisphere (90% of right-handed individuals, 70% of left-handed individuals).
But it’s important to remember that all functionality of the brain is a mutual effort of all four lobes of the brain. Without the proper functioning of all four lobes, we would have difficulty with basic motor function, sight, speech, and higher thinking processes handled by the frontal lobe.
Which Part of the Brain Deals With Sight?
Interestingly enough, vision is controlled by the part of the brain which is furthest away from the eyes themselves – the occipital lobe. It is located in the back of your head above the brain stem, the part of your brain that controls breathing.
The occipital lobe also has two hemispheres. The left hemisphere processes information from the right eye and vice versa.
The primary visual cortex (V1) gets raw information from the eyes and sends them to the secondary visual cortex for further processing. The secondary visual cortex (V2, V3, and V4) is made out of the ventral stream and dorsal stream. Visual stimuli are processed in the temporal lobe as well.
It’s important to keep the brain healthy and to challenge it with new tasks on a daily basis. That way, we can keep our brains strong and functioning well.
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