Localisation of Function of the Brain

Question 1

Localisation of Function

Answer 1

• Theory that different areas of brain are responsible for different behaviours, processes or acivities.

Question 2

Hemispheres

Answer 2

• 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.

Question 3

Frontal Lobe Specialism

Answer 3

• Higher level thinking.
• Speech
• Motor Control
• Coordinating info from all lobes.

Question 4

Parietal Lobe Specialism

Answer 4

• Receive and interpret sensory info.

Question 5

Occipital Lobe Specialism

Answer 5

• Receive and Process visual info.

Question 6

Temporal Lobe Specialism

Answer 6

• Process auditory info and important in memory.

Question 7

What does the specialism of each lobe mean?

Answer 7

• Each lobe has a localised function.
• 2 hemispheres have some different functions to one another.

Question 8

Somatosensory Area

Answer 8

• 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.

Question 9

Occipital Lobe

Answer 9

• 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.

Question 10

Motor Area

Answer 10

• 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.

Question 11

Auditory Area

Answer 11

• 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.

Question 12

Broca’s area

Answer 12

• 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.

Question 13

Wernicke’s area

Answer 13

• 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.

Question 14

Case of Phineas Gage

Answer 14

• 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.

Question 15

Case of Leborgne

Answer 15

• 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.

Question 16

Bridgemand and Staggs study
Overgaard et al

Answer 16

• 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.

Question 17

Brain scan evidence

Answer 17

• 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.

Question 18

Evaluation of Brain Localisation - Supporting Research

Answer 18

• 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.

Question 19

However - supporting research

Answer 19

• 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.

Question 20

Evaluation of Brain Localisation - scientific, objective data

Answer 20

• 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.

Question 21

However - scientific, objective data

Answer 21

• 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.

Question 22

Evaluation of Brain Localisation - Plasticity

Answer 22

• 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.

Question 23

However - Plasticity

Answer 23

• Individual differences need to be taken into account - gender, age and stress and perseverance are all factors that can affect functional recovery.