BP- Lateralisation of Function Flashcards
What is lateralisation of function?
- Lateralisation of function is the idea that the two hemispheres of the brain have different specialisations.
What is the left hemisphere dominant for ?
Language (Broca and Wernicke area)
What is the right hemisphere dominant for?
Visual motor tasks (Recognising faces)
What are the two hemispheres connected by?
A bundle of nerve fibres known as corpus callosum.
What is expressive aphasia?
- Language/speech problems caused by damage to Broca’s area.
- It affects language production but not understanding.
Where is the Broca’s area found?
Left hemisphere, frontal lobe
What is receptive aphasia?
- Receptive Aphasia is an impaired ability to understand language as a result of damage to the Wernicke’s area.
Where is the Wernicke’s area found?
In the left hemisphere of the temporal lobe.
What is split brain research?
When the corpus callosum has been cut in patients with epileptic seizures to prevent violent electrical activity crossing from one hemisphere to another.
Who investigated split-brain patients?
Sperry and Gazzaniga
Describe the research that Sperry and Gazzaniga conducted.
- Patients are asked to stare at a dot in the centre of a screen and info is presented in either left or right visual field.
- They’re then asked to make responses with either their left hand (right hemisphere) or right hand (left hemisphere) or verbally (left hemisphere) without being able to see what their hands were doing.
- E.g if they were flashed an image of a dog in the right visual field and they asked what they have seen. They will be able to answer “dog” because information would have gone into their left hemisphere which is where language centres are.
- If a picture of a cat is shown in the left visual field, they cant say it because info has gone into right hemisphere which has no language centres.
- However they can draw the picture with left hand because right hemisphere controls this hand.
What are the effects of the corpus callosum being cut?
- There is no way for the information presented to one hemisphere to travel to another.
- Info from left visual field goes into right hemisphere and vice versa.
Evaluate split brain research. (Disadvantages)
1) Many studies using split brain patients have as few as three participants, making it hard for results to be generalised.
ALSO
- The disconnection between the hemispheres is greater in some patients than in others, and some patients have drug therapy for their epilepsy which may affect the way in which their brain works. This means the findings of split-brain research cannot be generalised to the target population.
2)
- Research has found that language became more lateralised to the left hemisphere throughout childhood and adolescence but after the age of 25, lateralisation decreased with every decade.
- This shows our brain does not work in the same lateralised way throughout life and the fact that it changes with age makes us question Sperry and Gazzaniga’s conclusions.
- This is because if lateralisation is the brain’s way of functioning, it should be demonstrated by everyone regardless of age.
- Therefore lacks VALIDITY.
Evaluate split brain research. (Advantages)
1) Sperry and Gazzaniga’s research was an innovative and ingenious method that allowed scientists to scientifically study split brain patients.
- Scientists previously had a difficult time conceiving a standardized method in which all split brain patients could be investigated.
- Can be replicated
2) Has practical application
- Sperry and Gazzanigas conclusions can be applied to specifically design rehabilitation programmes that focus on verbal and visuo-spatial therapy for people who have brain damage.
- Can help those gone through damage to perform specific tasks to accelerate rate of recovery.
- Useful to improve lives
