Localisation of function and hemispheric lateralisation Flashcards Preview

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Flashcards in Localisation of function and hemispheric lateralisation Deck (28)
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1
Q

What is localisation?

A

The theory that different areas of the brain are responsible for different behaviours, processes or activities.

2
Q

What is the structure of the brain?

A
Two hemispheres (right and left).
Outer layer of both hemispheres = cerebral cortex.
3
Q

What are the 4 lobes in the cerebral cortex?

A

Frontal
Temporal
Occipital
Parietal

4
Q

What centre is the frontal lobe associated with?

What is its function?

A

Motor area

Regulates movement

5
Q

What centre is the parietal lobe associated with?

What is its function?

A

Somatosensory area

Processes sensory information, e.g. touch

6
Q

What centre is the occipital lobe associated with?

What is its function?

A

Visual area

Receives and processes visual information

7
Q

What centre is the temporal lobe associated with?

What is its function?

A

Auditory area

Analyses speech-based information

8
Q

What hemisphere of the brain is language associated with?

A

Left

9
Q

What are the 2 areas of the brain that are associated with language?

A

Broca’s area

Wernicke’s area

10
Q

What is Broca’s area responsible for?

Where is it?

A

Responsible for speech production.

Left frontal lobe.

11
Q

What happens if Broca’s area is damaged?

A

Broca’s aphasia - slow speech that lacks fluency.

12
Q

What is Wernicke’s area responsible for?

Where is it?

A

Responsible for language comprehension.

Left temporal lobe.

13
Q

What happens if Wernicke’s area is damaged?

A

Wernicke’s aphasia - produce nonsense words as part of the content of their speech.

14
Q

State 3 positives of localisation?

A

Brain scan evidence:
- Petersen - Wernicke (listening task) Broca (reading task)
- Tulving (episodic right prefrontal lobe, semantic left prefrontal lobe)
- Highly sophisticated and objective method and provides sound scientific proof
Neurosurgical evidence:
- Dougherty - 44 OCD patients who had undergone a cingulotomy (lesioning of cingulate gyrus)
- 32 week follow up - 1/3 met criteria for successful response
- suggests symptoms and behaviours associated with serious mental disorders are localised
Case study:
- Phineas Gage - personality (frontal lobe may be responsible of regulating mood)

15
Q

What is plasticity?

A

Describes the brain’s tendency to change and adapt as a result of experience and new learning.

16
Q

What was Maguire’s research into plasticity?

A
  • Studied brains of London taxi drivers and found significant grey matter in the posterior hippocampus than in the matched control group.
  • Posterior hippocampus - associated with the development of spatial and navigation skills.
  • Take extensive test which assesses their recall of the city streets and possible routes.
  • This learning experience altered the structure of their brains.
17
Q

What was Draganski’s research into plasticity?

A
  • Imaged brains of medical students 3 months before and after their final exams.
  • Learning-induced changes were seen to have occurred in the posterior hippocampus and the parietal cortex.
18
Q

What is functional recovery after a trauma?

A
  • A form of plasticity.

- The brains ability to redistribute functions to compensate for damaged parts of the brain following trauma.

19
Q

What happens to the brain during recovery?

A
  • Brain is able to rewire and reorganise itself by forming new synaptic connections close to the area of damage.
  • Secondary neural pathways are activated to enable functioning to continue.
20
Q

What are the 3 structural changes that occur to the brain during recovery?

A
  1. axonal sprouting - growth of new nerve endings which connect with other undamaged nerve cells to form new neural pathways.
  2. Reformation of blood vessels.
  3. Recruitment of homologous areas on the opposite side of the brain to perform specific tasks.
21
Q

State 2 positives of plasticity.

A

Practical application:
- neurorehabilitation
- spontaneous recovery tends to slow down after a number of week so physical forms of therapy may be required to maintain improvements in function
- electrical stimulation of the brain, movement therapy
Age and plasticity:
- Bezzola - how 40 hours golf training produced changes in the neural representation of movement in 40-60 year olds
- used fMRI scans - found reduced motor cortex activity in the novice golfers compared to a control group
- suggests more efficient neural representation after training
- neural plasticity does continue throughout lifespan

22
Q

State a negative of plasticity.

A

Negative plasticity:

  • may have maladaptive behavioural consequences
  • 60-80% of amputees have known to develop phantom limb syndrome
  • result of cortical reorganisation in the somatosensory cortex
23
Q

What is hemispheric lateralisation?

A

The idea that 2 halves of the brain are functionally different and that certain mental processes and behaviours are mainly controlled by one hemisphere than the other.
E.G. language (left)

24
Q

Who conducted research into hemispheric lateralisation?

Who was is conducted on?

A

Sperry
Conducted on patients who had undergone a commissurotomy (in which the corpus callosum is severed in order to control frequent and severe epileptic seizues).
So Perry could see the extent to which the 2 hemispheres were specialised for certain functions.

25
Q

What was the procedure of Perry’s study?

A
  • An image/word was projected to a patients right visual field (processed by left hemisphere).
  • The same or different image/word was projected to a patients left visual field (processed by right hemisphere).
  • In a ‘normal’ brain the corpus callosum would immediately share the information between the 2 hemispheres giving a complete picture of the visual world.
  • In a split brain patient the information couldn’t be shared.
26
Q

What were the findings of Sperry’s research?

A

Describing what you see:
- Pictures shown to RVF could be identified and described but not those to LVF because no language centres in left hemisphere (connected to RVF).
Recognition by touch:
- Could not describe objects projected to LVF but able to select a matching object from a selection of objects in a grab-bag using their left hand.

27
Q

State 2 positives of research into hemispheric lateralisation.

A

Demonstrated lateralised brain functions:
- Sperry produced a sizeable body of research
- main conclusion: left hemisphere is more geared towards analytic and verbal tasks, right hemisphere towards spatial and music tasks
Strengths of methodology:
- highly specialised and standardised
- allowed Sperry to vary aspects of the basic procedure to ensure that only one hemisphere was receiving information at a time

28
Q

State 2 negatives of research into hemispheric lateralisation.

A

Issues with generalisation:
- split brain patients = unusual sample
- only 11 people took part in all variations
- all had history of epileptic seizures which may have caused unique changes in the brain that influenced findings
Theoretical basis:
- debate about degree of communication between the 2 hemispheres