Blood Supply To The Brain
Two sets of blood vessels supply blood and oxygen to the brain: the vertebral arteries and the carotid arteries.
The external carotid arteries extend up the sides of your neck, and are where you can feel your pulse when you touch the area with your fingertips. The internal carotid arteries branch into the skull and circulate blood to the front part of the brain.
The vertebral arteries follow the spinal column into the skull, where they join together at the brainstem and form the basilar artery, which supplies blood to the rear portions of the brain.
The circle of Willis, a loop of blood vessels near the bottom of the brain that connects major arteries, circulates blood from the front of the brain to the back and helps the arterial systems communicate with one another.
What Is Broca’s Area And What Does It Do
In April of 1861, a 51-year old man named Louis Victor Leborgne was admitted to the surgical unit of young physician named Paul Pierre Broca. Leborgne had a severe leg infection that had become gangrenous, and Broca did not think it likely he would survive. Broca took much more interest in Leborgne than he would have in just another patient with cellulitis, however, as Leborgne also had a more unique disorder. The disorder, which Broca would come to all aphemia and which would later be named aphasia , caused Leborgne to have an extremely difficult time producing language. In fact the only word he could consistently generate was the word “tan,” which he would often utter in two-word refrains of “tan, tan.” Leborgne had thoughts he wanted to communicate, but he was unable to. He used gestures to interact with Broca, but sometimes became frustrated at his inability to express himself—causing him to utter the only other words Broca reported hearing him say: “sacre nom de Dieu,” or God damn.
Watch this 2-Minute Neuroscience video to learn more about Brocas area.
Although some of these additional functions linked to Broca’s area may be associated with the region’s role in language, they also make it clear that the function of Broca’s area is much more complex than originally thought. Thus, the role of Broca’s area in linguistic and non-linguistic functions is still being elucidated, and will likely be modified and expanded upon many times in the future.
To The Left Cortex And Beyond
It has long been established that humans capacity to use their native language is stored in the left hemisphere of the brain in over 90% of the normal population. The main parts of the brain involved in language processes are the Brocas area, located in the left frontal lobe, which is responsible for speech production and articulation, and the Wernickes area, in the left temporal lobe, associated with language development and comprehension.
Language learning, however, is a complex procedure that scientists have determined is not limited to any hemisphere of the brain, but instead involves information exchange between the left and the right sides. Nothing that comes as a surprise, if we consider just how many elements a single language entails.
But the complexity doesnt stop here. The part of the brain where humans store a second language varies according to the age they acquire it. A study conducted at the Memorial Sloan-Kettering Cancer Center in New York with the help of 12 bilingual volunteers revealed that children who learn a second language early on store it together with their native language, while in adult learners it is saved in a different area of the brain. This suggests that the brain accommodates languages separately at different points of the subjects lifespan, which means the structures involved in language acquisition and processing are not fixed, but change, undergoing cortical adaptation when a new language is added.
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Left Or Right Hemisphere Of The Brain: Learning A Foreign Language
If you’re reading this, your brain is performing a series of functions that allows you to recognize the patterns of the letters and words, put them in the correct order and comprehend their meaning. Until the late 20th century, scientists believed that almost everything you do, including the ability to learn a foreign language, was determined by which side of your brain you are using.
Patterns Of Brain Activation In Adults
The patterns of brain activation observed during performance of CN tests have also been analyzed using structural MRI and diffusion tensor imaging data, and reports indicate that the volumes of the left mid-frontal gyrus and right middle temporal gyrus correlate with accuracy on the Action Naming Test , while the volumes of the left mid-frontal gyrus and left planum temporale were seen to be negatively correlated with reaction times for correct trials on the BNT . Also, subjects with greater white matter density tended to achieve greater accuracy and faster reaction times. Better naming abilities were associated with the use of the bilateral perisylvian and dorsolateral frontal areas of both hemispheres. The authors of this study suggested that the older adults with relatively better naming ability may be relying on right-hemisphere perisylvian and mid-frontal regions and pathways in conjunction with left-hemisphere perisylvian and mid-frontal regions to achieve better test performance.
Figures , , and present some examples of fMRI activation during different language tasks.
fMRI activation in a right handed 13-year-old boy while performing a verb generation task. Activation of left Broca’s area is observed. The small coactivation of the medial frontal cortex is most likely related to selective attention, required during the task. Courtesy Dr. Byron Bernal, Miami Children’s Hospital, Radiology Department. Miami, FL, USA.
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Patterns Of Brain Maturation
Verbal generation measured by VF tests and vocabulary size measured by naming tests are obviously correlated with some of the neuroanatomical and neurophysiological changes that occur in the brain during childhood and adolescence. Functional and structural MRI studies have shown that one of the most important aspects of maturation across the cerebral cortex after age 5 is the overall decrease in gray matter volume and the continuous increase in the volume of white matter . The development of GM follows an inverted U pattern, with initial growth followed by a continuous decrease . The age at which this decrease in GM begins varies across the cerebral cortex; for example, the frontal system reaches its GM peak between the ages of 1214 years, while in the temporal lobe this occurs around age 17-18, and in the parietal at 1012 years. In contrast, the total volume of WM increases continuously . Giorgio et al. used diffusion-weighted magnetic resonance imaging to test for age-related WM changes in 42 adolescents . They found that the increase of WM is much more prominent than the decrease in GM, results which revealed that the most significant changes were in the body of the corpus callosum and the right superior region of the corona radiata .
Changes in gray and white brain matter between the ages of 4 and 22 years in males .
Language Processing In The Brain
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Dual stream connectivity between the auditory cortex and frontal lobe of monkeys and humans.
Language processing refers to the way humans use words to communicate ideas and feelings, and how such communications are processed and understood. Language processing is considered to be a uniquely human ability that is not produced with the same grammatical understanding or systematicity in even human’s closest primate relatives.
The division of the two streams first occurs in the auditory nerve where the anterior branch enters the anterior cochlear nucleus in the brainstem which gives rise to the auditory ventral stream. The posterior branch enters the dorsal and posteroventral cochlear nucleus to give rise to the auditory dorsal stream.:8
Language processing can also occur in relation to signed languages or .
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What Part Of The Brain Controls Speech
Your brain is responsible for nearly all functions of your body and for interpreting sensory information from the world around you.
Your brain has many parts but speech is primarily controlled by the largest part of the brain, the cerebrum.
The cerebrum can be divided into two parts, called hemispheres, which are joined by a band of nerve fibers called the corpus callosum.
Your speech is typically governed by the left side of your cerebrum. In about a third of people who are left-handed, however, speech may actually be controlled by the right side.
Confrontation Naming And Verbal Fluency In Adults
It has often been assumed that word retrieval difficulties are found commonly in older adults; indeed, several studies have reported evidence supporting an age-related decline in lexical retrieval ability . However, other research has failed to find evidence of such an age-associated lexical retrieval defect . We can conjecture, therefore, that there may be some variability in the decline in lexical retrieval or perhaps that the different experimental approaches using distinct tasks with a variety of study population account for some of the variation in results.
Kent and Luszcz , for example, studied an initial sample of 803 people with an average age of 76 who underwent an initial examination and a follow-up evaluation 2 years later. Finally, a subsample of 326 subjects was reevaluated 6 years after that. Results indicated that age and educational level, but not gender, affected naming ability. The authors concluded that there was a continuous decline in naming ability that correlated inversely with age. Such findings have been observed in both cross-sectional and longitudinal studies. Interestingly, in a 20-year longitudinal study, Connor et al. reported a decline of approximately 2% per decade in BNT scores.
Average Boston naming scores by age groups .
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The Brain Behind Language Learning
There are so many different factors to take into consideration when it comes to identifying why a student is having trouble understanding language and learning to read. A physical or innate problem, such as the way the brain works, is often a factor that is overlooked and may be hard to pinpoint.
Several areas of the brain must function together in order for a person to develop, utilize and understand language. Lets take a look.
- Brocas area: Located in the;frontal lobe;of the brain, is linked to speech production, and recent studies have shown it to also play a significant role in language comprehension. Brocas area works in conjunction with working;memory;to allow a person to use verbal expression and spoken words.
- Wernickes area: Located in the;cerebral cortex, this is the part of the brain involved in understanding written and spoken language. Damage to this area results in speech that is unable to be understood by others.
- Primary auditory cortex: Located in the;temporal;lobe and connected to the auditory system, this area is organized so that it responds to neighboring frequencies in the other cells of the cortex. It is responsible for identifying pitch and loudness of sounds.
- Angular gyrus: Located in the parietal lobe of the brain, this area is responsible for several language processes, including number processing, spatial recognition and attention.
Auditory Cortex And Angular Gyrus
The primary auditory cortex, located in the;temporal;lobe and connected to the auditory system, is organized so that it responds to neighboring frequencies in the other cells of the cortex. It is responsible for identifying pitch and loudness of sounds.
The angular gyrus, located in the parietal lobe of the brain, is responsible for several language processes, including number processing, spatial recognition and attention.
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Language Reception And Understanding: Lexical
In four different meta-analytic studies, the role of BA20, BA37, BA38, and BA39 in language was analyzed .
BA20 . Eleven papers, corresponding to 12 experimental conditions, and 207 participants were used in this analysis. Our results demonstrated seven clusters of activation: The first cluster included the left temporal lobe, BA20 and BA21, whereas Cluster #2 was located at the left insula and left prefrontal BA46. Cluster #3 involved the left inferior frontal lobe and Cluster #4 was situated in the left inferior temporal lobe . Cluster #5 was again situated in the left prefrontal cortex . The last two clusters involved the cingulate gyrus and the left occipital gyrus .
There were few activated areas outside the temporal lobe: insula , prefrontal cortex , cingulate gyrus , and the occipital lobe . All seven clusters were located in the left hemisphere.
Eleven papers, corresponding to 12 experimental conditions, and 201 participants were selected . Four different clusters of activity were found: two in the left and two in the right hemisphere . The first cluster included BA38, while the second contained the left insula and superior temporal lobe . The last two clusters involved were the right parietal and temporal lobes. Seemingly, this area has two major connection pathways: one within the left hemisphere and the other involving the right hemisphere plausibly participating in visuospatial and integrative audiovisual functions.
Languages Are Living Things
Lera Broditsky, an associate professor of cognitive science at the University of California, San Diego who specializes in the relationship between language, the brain, and a persons perception of the world has also been reporting similar findings.
In a TED talk she gave in 2017, which you can watch below, Broditsky illustrated her argument about just how greatly the language we use impacts our understanding of the world.
As an example, she uses the case of the Kuuk Thaayorre, an Australian tribe that uses cardinal directions to describe everything.
And when I say everything, I really mean everything,’ she emphasized in her talk. You would say something like, Oh, theres an ant on your southwest leg, or, Move your cup to the north northeast a little bit,’ she explains.
This also means that when asked in which direction the time flows, they saw it in relation to cardinal directions. Thus, unlike Americans or Europeans who typically describe time as flowing from left to right, the direction in which we read and write they perceived it as running from east to west.
The beauty of linguistic diversity is that it reveals to us just how ingenious and how flexible the human mind is. Human minds have invented not one cognitive universe, but 7,000. 7,000 languages spoken around the world. And we can create many more. Languages are living things, things that we can hone and change to suit our needs.
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The Lobes Of The Brain
Each hemisphere of the brain is divided into functional sections known as lobes. There are four lobes in each half of the brain. They are:
- Frontal lobe: Located at the front of the brain, right behind the forehead. The frontal lobe is quite large, occupying about one-third of the cerebral cortex’s total mass, and it controls personality, behavior, emotional regulation, and the ability to plan, solve problems, and organize.
- Parietal lobe: Located near the back and top of the head, above the ears. The parietal lobe controls the ability to read, write, and understand spatial concepts.;The function of the left and right parietal lobes do not completely mirror each other, with the dominant parietal lobe controlling speech and logic, while the non-dominant parietal lobe controls spatial skills and creativity. In fact, a stroke affecting the non-dominant parietal lobe can produce its own set of problems, including disorientation and an inability to recognize one’s own body.
- Occipital lobe: A small region located at the back of the head. The occipital lobe is responsible for the integration of vision.
- Temporal lobe: Located at the side of the head above the ears and below the frontal lobe. The temporal lobe controls hearing, memory, speech, and comprehension.
Language Development In Infancy And The Preschool Years
It has been well established that newborns respond to auditory stimuli in the range of language frequencies and show an overt preference for verbal sounds , suggesting a biological predisposition to detect and process human language signals. From 2 to 8 months, babies demonstrate an evident orientation to verbal sounds that gives rise to the so-called mother/father-child dialogue. Using the habituation paradigm , it has been shown that babies aged 22 to 140 days are capable of detecting consonant-vowel changes much better in the right ear than the left one , a finding which indicates that the left hemisphere is likely involved in processing language-related signals right from birth . This is a particularly important finding because it suggests an inborn brain asymmetry for language.
Consequently, it is important not only to consider biological variables when analyzing brain organization and the lateralization of language but also to include interaction with environmental conditions. It could be conjectured that the brain mechanisms required for language are not fixed at birth but present a dynamic organization during their development and exposure to language .
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What Happens To Your Brain When You Learn A New Language
In 2013, a group of researchers from the University of Edinburgh published the largest study to date about the correlation between bilingualism and progression of dementia and other cognitive diseases like Alzheimers. The subjects were 648 patients from Hyderabad, the capital city of the state of Telangana, in India. Telugu and Urdu are the predominant languages in that region, where English is also commonly used. Most of the residents of Hyderabad are bilingual, 391 of whom were part of the study. The conclusion was that the bilingual patients had developed dementia, on average, four and a half years later than the monolingual ones, strongly suggesting that bilingualism has a deep impact on neurological structures and processes.
The process of acquiring a second language might be one we dedicate a lot of time and effort to, at school for example, but in some cases it happens naturally . So how can it be that this process, regardless of how it takes place, has such a big impact on the brain?