Localisation of Function of the Brain Flashcards
1
Q
Localisation of Function
A
- Theory that different areas of brain are responsible for different behaviours, processes or acivities.
2
Q
Hemispheres
A
- Brain is divided into two halfs - left and right hemispheres.
- Some functions located more in one hemisphere than the other - known as lateralisation.
- Brain hemispheres are contralateral - right hemisphere controls persons left hand side and vice versa.
- Hemispheres connected by corpus callosum.
- Outside layer of both hemispheres called cortex - ours is bigger proportionally than less developed species.
- Supdivided into 2 lobes.
3
Q
Frontal Lobe Specialism
A
- Higher level thinking.
- Speech
- Motor Control
- Coordinating info from all lobes.
4
Q
Parietal Lobe Specialism
A
- Receive and interpret sensory info.
5
Q
Occipital Lobe Specialism
A
- Receive and Process visual info.
6
Q
Temporal Lobe Specialism
A
- Process auditory info and important in memory.
7
Q
What does the specialism of each lobe mean?
A
- Each lobe has a localised function.
- 2 hemispheres have some different functions to one another.
8
Q
Somatosensory Area
A
- Front of both parietal lobs.
- Sensory info from the skin is represented.
- Processes heat, touch and pressure.
- More receptors for more sensitive areas of the body - face and hands occupy half the area.
9
Q
Occipital Lobe
A
- Back of the brain - visual area.
- Eyes send info from right visual field to left visual cortex and vice versa.
- Damage to left hemisphere can result in blindness in right visual field of each eye.
- If a specific area is damaged called Area V1 then visual perception is problematic.
- Patients report no vision of any kind including conscious vision, imagery while awake or in their dreams.
10
Q
Motor Area
A
- Controls voluntary movement in opposite side of the body.
- In both hemispheres behind the frontal lobe.
- If damaged it can result in loss of control over fine movements.
- Areas that control specific parts of the body within it.
- Number of neurons needed to move a part of the body is not related to its size but its complexity of movement.
11
Q
Auditory Area
A
- In temporal lobes.
- Responsible for processing speech based info.
- Receives info from both ears.
- Info from right ear goes primarily to left hemisphere.
- Damage results in partial hearing loss and more extensive damage the more severe the loss.
- Complex sounds such as music are more difficult to process after damage.
- Two important areas linked to language - found in left hemisphere.
12
Q
Broca’s area
A
- In left frontal lobe - responsible for speech production.
- If damaged a person would have Broca’s aphasia.
- Speech is slow, laborious and lacks fluency.
- Usually limited to 4 word sentences.
- Comprehension can be fine and are able to read but have limited writing ability.
13
Q
Wernicke’s area
A
- Left posterior temporal lobe is responsible for language comprehension.
- Damaged causes clear speech that is meaningless and have severe difficulties understanding speech.
- Known as Wernicke’s aphasia.
- Unaware they are not making any sense.
- Have anomia - when someone struggles to find the word they need.
- Severely impaired reading and writing.
14
Q
Case of Phineas Gage
A
- Landmark case that suggested that frontal lobe was linked to mood regulation.
- Whilst working on a railroad his tampling iron was forced through his skull after an explosion.
- Survived even though a part of his brain was missing.
- His personality changed from being calm and friendly to being quick tempered and rude.
- Physically well but blind in one eye.
- Doctor at the time believed the area damaged had been responsible for planning, reasoning and self control.
15
Q
Case of Leborgne
A
- Died aged 51 - supports Broca’s aphasia.
- Was an epileptic who gradually lost power of speech but could say ‘tan’.
- Paul Broca treated him and carried out a post mortem where he found a lesion to left frontal lobe but no other damage.
- Despite the age of the research it is considered a robust finding has been supported by more recent research.
16
Q
Bridgemand and Staggs study
Overgaard et al
A
- Found that patients with Area V1 damage show blindsight - able to point where objects are despite being blind.
- Reported the case of GR - woman with blindsight - result of haemorrhage in left occipital lobe.
- Even though she was cortically blind, she could detect a letter on a screen despite seeing nothing.
- Reported an awareness of something.
- Suggests could be 2 types of vision - conscious and unconsciour and functions are located in different areas of brain.
17
Q
Brain scan evidence
A
- Extensive for localisation of function.
- Peterson et al demonstrated how Wernicke’s area was active when listening and Broca’s area active when reading.
- Supports idea that they have seperate language related functions.
18
Q
Evaluation of Brain Localisation - Supporting Research
A
- Wealth of evidence supporting view of different parts of brain have differing functions.
- Phineas Gage.
- Varied evidence, case studies, brain studies and post mortems.
- Strength - suggests findings are robust.
19
Q
However - supporting research
A
- Some evidence has used neurological case studies - Phineas Gage.
- Limited as they are only of one person and cannot be generalised.
- However - not practical or ethical to cause brain damage as part of a study to see what happens.
- Researchers can only use cases presented to them such as stroke victims, head injuries etc.
- Some case studies are old.
- Weakness - info gained from case studies can not be generalised to everyone.
20
Q
Evaluation of Brain Localisation - scientific, objective data
A
- Now exists a range of scientific, sophisticated ways of studying the brain.
- fMRI - objectiv, create a lot of info, far better than relying on post mortems as they allow researchers to see brain in real time.
- Strength - methodologies are valid and relaible.
21
Q
However - scientific, objective data
A
- Lashley suggested that some complex functions such as learning use every area of the cortex rather than confined to one area.
- Saw functionality more holisticially.
- Supported his view in experiment on rats - removed 10-50% of cortex and tested ability to learn mazes.
- No area removed proved to be more important and concluded that learning requires involvement of whole brain.
- Weakness - throws into question whole notion that brain function is localised. More recent research shows connections between areas are as important as areas themselves.
22
Q
Evaluation of Brain Localisation - Plasticity
A
- Cases where people have lost some brain function after a brain injury or stroke appear to later regain it.
- Called plasticity or cortical remapping - brain reorganises or rewires itself to compensate for damage.
- Weakness - suggests that neurons can adapt and compensate for damaged areas, not consistent with view that brains functions are localised.
23
Q
However - Plasticity
A
- Individual differences need to be taken into account - gender, age and stress and perseverance are all factors that can affect functional recovery.