StudySmarter - The all-in-one study app.
4.8 • +11k Ratings
More than 3 Million Downloads
Free
Localisation of function in the brain is the concept that some brain regions are responsible for particular functions. They carry out and oversee the functions of behaviours and processes due to their structure and position. Examples include moving a limb or being able to speak.
This idea contrasts with the holistic view of the brain, which says that the brain's functions spread across large areas, if not the entire brain itself.
Therefore, when a particular brain area is damaged, this affects that area's associated function.
The brain has a left and right half called hemispheres which operate contralaterally.
Contralaterally refers to the side of the body opposite to which a function is responsible. So, the right hemisphere is responsible for the left side of the body and vice versa.
The corpus callosum connects the hemispheres.
Each hemisphere specialises in performing certain functions, which is called hemispheric lateralisation.
The cerebral cortex is critical. It is a thin outer layer of neural tissue, usually 2-4mm thick, of the brain. It is folded for the extra space (the bumps and ridges are known as the gyri, and the sulci are the furrows) and contains mainly cell bodies. Often referred to as grey matter, higher cognitive processes occur there, such as consciousness, reasoning, emotions, and language, amongst other things.
Particular areas are well-known for their relation to specific functions in the brain. Evidence for localisation of function can be seen in multiple aspects of the brain.
The prefrontal cortex is part of complex cognitive processes and higher-level functions. It is involved in executive functions (sorting through complicated and conflicting thoughts etc.) and working memory, orchestrating thoughts and personality expression and performing cognitive functions whilst inhibiting impulsive thoughts and actions.It is said to be directly involved with consciousness and sentience, so it is incredibly influential on cognitive functions and processes as a whole!
The motor and somatosensory cortex are areas of the cerebral cortex that run along a fold in the brain called the central sulcus. The motor cortex, responsible for muscle control, is located at the back of the frontal lobe, and the somatosensory cortex, responsible for processing sensations, is located in the parietal lobe.
The functions are carried out contralaterally. If you were to move your left hand, neurones in the right motor cortex would activate. Similarly, if you feel something tickle your left hand, the right sensory cortex would activate.
The motor cortex is responsible for:
Damage to these areas can result in the loss of the above functions. Paralysis may occur, as there's a loss of voluntary control over muscles. It is difficult to sequence movements or actions. For example, it would be harder to get dressed. Dexterity is affected; when the motor cortex is damaged, the more complex the movements are, the harder it is to carry them out. Eventually, with damage and muscle control loss, the muscles will become weaker, resulting in atrophy (loss) of the muscles.
The somatosensory cortex is situated in the postcentral gyrus (the bumps and ridges that make up the cerebral cortex), found in the parietal lobe, as seen in the above diagram.
The somatosensory cortex is contralaterally responsible for:
Receiving and processing sensations, such as touch and temperature.
Damage to the somatosensory cortex causes a loss of sensation from the opposite side of the body. It can result in one area being completely ignored, or there may be a loss of ability to recognise an object by its feel, known as agnosia.
The visual cortex is located in the occipital lobe at the back of the brain.
Light enters the eye and is converted into nerve impulses by the retina (located at the back of the eye). The optic nerve transmits these impulses to the thalamus and the visual cortex.
The right hemisphere processes visual information of the left eye, and vice versa for the left hemisphere. It operates contralaterally.
It is responsible for:
Damage to the visual cortex can result in partial or complete contralateral blindness, known as cortical blindness.
The auditory cortex is located at the top of the temporal lobe. The primary auditory cortex receives auditory information from the thalamus, which receives sound impulses (sensations) from the cochlea.
The cochlea converts sound waves into nerve impulses, carried by the auditory nerve for the auditory cortex to process and interpret.
The auditory cortex is responsible for:
Damage to this area can cause issues such as being unable to detect changes in a person's pitch or tone of voice, making conversing with someone and interpreting their intentions extremely difficult. If someone is serious or sarcastic, it would be hard to tell by pitch or tone alone. They wouldn't be able to determine where or what produced the sound.
Broca's area is located in the left frontal lobe, as illustrated below:
The exact location of Broca's area is up for debate, but researchers agree that it is located in the left frontal lobe.
It is responsible for:
Broca's area is in the left hemisphere specifically. The right hemisphere has a similar area, but it's not as pertinent.
Broca discovered the area when a patient with a severe leg infection came to him and could only produce the word 'tan'. The patient struggled immensely with speech production. The patient wanted to communicate but just couldn't. The only words Broca heard him say were 'God damn' in French due to his frustration over not speaking.
After the patient died, Broca performed an autopsy and found a large crater in the left frontal lobe. Broca ascribed this lesion (damage) to the loss of speech production in the patient. He discovered eight more cases with similar evidence and speech production issues to confirm this. It was the same place and on the left side.
The original patient became the first to be described as suffering from Broca's aphasia (a loss of ability to produce speech due to brain damage).
Therefore, the function of speech production was localised to Broca's area.
Wernicke's area is primarily said to be located in the upper temporal lobe, shown below:
It resides in the left hemisphere. The left hemisphere is becoming increasingly prominent in its dominance of language production functions.
Wernicke suggested damage in the left hemisphere, specifically the area we're discussing, would result in fluent but meaningless speech.
Patients could speak with fluent sounds and inflexions (changes in pitch to give meaning), but when listened to, the sound made little sense. This disorder is known as Wernicke's Aphasia. People often also struggle to understand language with this disorder.
Wernicke proposed a model including his and Broca's area to state that Wernicke's area is responsible for meaningful speech, and Broca's area is responsible for making plans and generating speech (through moving the mouth and tongue).
Damage to Wernicke's area does not always wholly disrupt comprehension, suggesting it is just one component of language comprehension.
Damaging Broca's and Wernicke's areas can result in global aphasia, where patients struggle to produce and understand speech.
There are strengths and weaknesses for the argument of localisation of function within the brain.
Localisation is the concept that certain brain areas are responsible for particular functions. This idea contrasts with the holistic view of the brain, which essentially says that the brain's functions spread across large areas, if not the entire brain itself.
Hemispheric lateralisation is where each brain hemisphere is specialised to perform certain functions. The brain generally operates contralateral.
The motor cortex is responsible for motor control, and the somatosensory cortex is responsible for sensation processing.
The visual cortex is responsible for visual processing functions and perceiving information. Damage to the visual cortex can result in partial or complete contralateral blindness, known as cortical blindness. The auditory cortex is responsible for sensing sound. Damage to this area can cause issues with understanding speech, what sound came from, and what specific sounds mean.
Broca's and Wernicke's areas are in the left hemisphere specifically. Broca's area is responsible for speech production, Wernicke's area is responsible for speech comprehension.
Both modern and old research supports localisation – fMRI shows activated areas, and damage to these areas disrupts associated functions. TMS can actively disrupt localised functions, and double dissociations support localised functions.
Issues arise with equipotentiality theory, beta bias, and how damage can extend beyond localised areas but still affect the functions associated with those areas.
Localisation of function in the brain is important because it helps researchers identify brain areas that could be responsible for specific functions. It aids massively in researching the complexity of the organ.
Functional localisation is the concept that some brain regions are responsible for particular functions.
Localisation is where a specific brain area is associated directly with a particular function. Lateralisation is where the brain has two hemispheres connected by the corpus callosum, and each hemisphere of the brain is specialised to perform certain functions or processes.
Many areas of the brain are associated with memory control. This includes the prefrontal cortex, the amygdala, the hippocampus, and the cerebellum.
of the users don't pass the Localisation of Function in the Brain quiz! Will you pass the quiz?
Start QuizBe perfectly prepared on time with an individual plan.
Test your knowledge with gamified quizzes.
Create and find flashcards in record time.
Create beautiful notes faster than ever before.
Have all your study materials in one place.
Upload unlimited documents and save them online.
Identify your study strength and weaknesses.
Set individual study goals and earn points reaching them.
Stop procrastinating with our study reminders.
Earn points, unlock badges and level up while studying.
Create flashcards in notes completely automatically.
Create the most beautiful study materials using our templates.
Sign up to highlight and take notes. It’s 100% free.