Biopsychology: Localisation of function

Question 1

What is localisation of function?

Answer 1

Refers to the belief that specific areas of the brain are associated with specific cognitive processes.

Certain areas of the brain are thought to be responsible for particular functions.

Question 2

What are the 6 parts of the brain?

Answer 2

• Motor cortex
• Somatosensory cortex
• Wernike’s area
• Visual cortex
• Auditory cortex
• Broca’s area

Question 3

What are the 3 types of centres in the brain?

Answer 3

• Visual and auditory centres
• Motor and somatosensory areas
• Language centres

Question 4

What is the Broca’s area?

Answer 4

• Broca’s area is the main area where speech is produced. It is located in the frontal lobe of the left hemisphere.
• The Broca’s area was identified by and named after Pierre Paul Broca in the mid 19th Century. From post-mortem autopsies, Broca observed that patients who had difficulty producing words had lesions (damage) in this area of the brain.
• Damage to the Broca’s area causes Broca’s aphasia (also called expressive aphasia), a condition characterised by slow speech, lack of fluency, and an inability to find the right words. Despite difficulties producing speech, people with Broca’s aphasia often have normal language comprehension – i.e. they understand what others are saying.

Question 5

What is the motor cortex?

Answer 5

Located in the posterior frontal lobe. The motor cortex of the brain is responsible for voluntary movements, such as walking. However, basic involuntary movements (like coughing) are controlled by other parts of the brain.

So, damage to the motor cortex may limit a person’s motor skills. For example, a person with a damaged motor cortex may have difficulty holding a pen.

It will also affect the right side of her body.

Question 6

What is the somatosensory?

Answer 6

The somatosensory cortex of the brain is responsible for sensing physical sensations on the skin, like pressure and heat. It is located in the parietal lobes of each hemisphere.

The number of neurons in the somatosensory cortex differs according to the body part. For example, there are many more neuronal connections dedicated to processing information from the hands than the ankles because people use their hands to feel things much more commonly than they do their ankles.

Question 7

What is the visual cortex?

Answer 7

The visual cortex of the brain is responsible for processing visual information from the eyes. It is located in the occipital lobes of each hemisphere. The visual cortex is contralateral: The right hemisphere processes data from the left of a person’s field of vision (both eyes) and vice versa.

So, damage to the visual cortex of the right hemisphere may make it difficult for a person to perceive objects to the left of them.

Question 8

What is the Wernike’s area?

Answer 8

• Another important (but separate) area for language is Wernicke’s area. The Wernicke’s area is primarily responsible for language comprehension (both written and spoken). It is located in the temporal lobe.
• Damage to Wernicke’s area causes Wernicke’s aphasia (also called receptive aphasia). Patients with Wernicke’s aphasia typically have no problems producing speech – they speak in a fluent and effortless way – but the content of what they say often lacks

Question 9

What is the auditory centre?

Answer 9

The auditory cortex of the brain is responsible for processing sound. It is located in the temporal lobes of each hemisphere. The auditory cortex is also contralateral: The right hemisphere processes sound from a person’s left ear and vice versa.

So, damage to the auditory cortex of the left hemisphere may cause hearing difficulties in a person’s right ear.

Question 10

What is the brain divided up into?

Answer 10

Two hemispheres

Question 11

What are the 2 hemispheres connected by?

Answer 11

The corpus callosum

Question 12

A03: Localisation of function

Answer 12

+ Importance of case studies

+ Research support (Sarah Scott)

• Individual differences
• Communication may be more important than localisation

Question 13

A03: Importance of case studies

Answer 13

There is a wealth of case studies on patients with damage to Broca’s and Wernicke’s areas that have demonstrated their functions. For example, Broca’s aphasia is an impaired ability to produce language; in most cases, this is caused by brain damage in Broca’s area. Wernicke’s aphasia is an impairment of language perception, demonstrating the important role played by this brain region in the comprehension of language.

Question 14

A03: Research support from Sarah Scott

Answer 14

A British girl named Sarah Scott suffered a stroke at 18 and developed Broca’s aphasia as a result. It is a great example of the sorts of difficulties that Broca’s aphasia can involve. These can be the output of spontaneous speech markedly diminished. There is a loss of normal grammatical structure (agrammatic speech). Specifically, small linking words, conjunctions (and, or, but), and the use of prepositions are lost.

Question 15

A03: Individual differences

Answer 15

Finally, some psychologists argue that the idea of localisation fails to take into account individual differences. Herasty (1997) found that women have proportionally larger Broca’s and Wernicke’s areas than men, which can perhaps explain the greater ease of language use amongst women. This, however, suggests a level of beta bias in the theory: the differences between men and woman are ignored, and variations in the pattern of activation and the size of areas observed during various language activities are not considered.

Question 16

A03: Communication may be more important than localisation

Answer 16

Psychologists suggest that it is more important to investigate how the brain areas communicate with each other, rather than focusing on specific brain regions. Wernicke claimed that although the different areas of the brain are independent, they must interact with each other in order to function. An example to demonstrate this is a man who lost his ability to read, following damage to the connection between the visual cortex and the Wernicke’s area, which was reported by Dejerine. This suggests that interactions between different areas produce complex behaviours such as language. Therefore, damage to the connection between any two points can result in impairments that resemble damage to the localised brain region associated with that specific function. This reduces the credibility of the localisation theory.