3 - Brain Localisation + Lateralisation Flashcards

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1
Q

What is localisation?

A

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

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2
Q

What is another term for brain localisation?

A

Cortical specialisation

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3
Q

What was the belief about brain function before the localisation theory?

A

Holistic theory (all parts of the brain work together to cause processes/behaviours)

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4
Q

What will damage to a certain area of the brain cause?

A

The loss/impairment of the certain function associated with that area

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5
Q

What are the three concentric layers that make up the brain?

A
  • The central core
  • The limbic system
  • The cerebrum
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6
Q

Which concentric layer do we look at predominantly regarding brain localisation + lateralisation?

A

The cerebrum

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7
Q

Outline the features + function of the central core

A

Features…

  • Bottom layer of brain
  • Includes: brain stem, cerebellum, hypothalamus

Functions…

  • Regulates primitive functions (eating, sleeping, etc)
  • Helps with homeostasis (maintaining constant bodily state)
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8
Q

Outline the features + functions of the limbic system

A

Features…

  • Middle layer of brain
  • Includes: connection to hypothalamus, hippocampus

Functions…
- Regulates emotions

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9
Q

Outline the features + functions of the cerebrum

A

Features:

  • Made of left + right hemispheres
  • Hemispheres connected by corpus callosum

Functions:

  • Regulating higher intellectual processing
  • Lateralisation suggests left + right side have differently functions
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10
Q

What is lateralisation?

A

Theory that the two hemispheres of the brain (of the cerebrum) are functionally different + responsible for different mental processes + behaviours

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11
Q

What is the right hemisphere’s function?

A
  • Controls left side of body
  • The ‘synthesiser’ (holistic)
  • Specifically important for: emotion, holistic thought, creativity, face recognition
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12
Q

What is the left hemisphere’s function?

A
  • Controls right side of body
  • The ‘analyser’ (breaks down + analyses)
  • Specifically important for: language, analytical thought, logic + sequencing
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13
Q

What is the corpus callosum

A

The bundle of fibres that connects the two cerebral hemispheres
- Enables communication between hemispheres

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14
Q

How many lobes is each hemisphere divided into?

A

4

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15
Q

What are the names of the hemispheres’ lobes + their basic function?

A
  • Frontal lobe (movement, thinking, emotions)
  • Parietal lobe (senses, attention)
  • Temporal lobe (hearing)
  • Occipital lobe (vision)
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16
Q

What are the lobes of the cerebral hemisphere covered in?

A

Cerebral cortex (grey, 3mm thick, divided into multiple cortices)

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17
Q

What are the cerebral cortex’s cortices?

A
  • Motor cortex
  • Somatosensory cortex
  • Auditory cortex
  • Visual cortex
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18
Q

Motor cortex - location? Function? Effect of damage?

A

Location: back of frontal lobes

Function: conscious movement (control opposite sides of body)

Effect of damage: loss of control over fine movements

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19
Q

Somatosensory cortex - location? Function? Effect of damage?

A

Location: front of parietal lobes

Function: representation of sensory info, e.g. feeling pain, heat, etc

Effect of damage: issues processing sensory info

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20
Q

Auditory cortex - location? Function? Effect of damage?

A

Location: temporal lobe (by ears)

Function: receiving + processing auditory info (hearing)

Effect of damage: loss of hearing

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21
Q

Visual cortex - location? Function? Effect of damage?

A

Location: back of occipital lobes

Function: sending visual info from visual field to opposite visual cortex (sight)

Effect of damage: loss of vision (blindness)

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22
Q

Which side of the brain is language lateralised to?

A

Left

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23
Q

What are the two language centres of the brain?

A
  • Broca’s area

- Wernicke’s area

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24
Q

Broca’s area - location? Function? Effect of damage? Discovered by?

A

Location: left frontal lobe

Function: language production (speech)

Effect of damage: Broca’s aphasia - cannot produce speech properly (slow + broken)

Discovered by: Looking at Patient Tan (could understand language heard but could only say one syllable: ‘Tan’)

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25
Q

Wernicke’s area - location? Function? Effect of damage? Discovered by?

A

Location: left temporal lobe

Function: language comprehension (understanding)

Effect of damage: Wernicke’s aphasia - can only produce neologisms (nonsense speech) that isn’t understandable

Discovered by: Looking at patients with damaged left temporal lobes

26
Q

Give 2 positive evaluation points for localisation of brain function

A

Evidence from brain scans

  • Brain scans show brain activity in certain areas when completing certain tasks
  • E.g. Peterson et al used scans to show Broca’s area activity during a reading task + Wernicke’s area activity during a listening task - supporting localisation of language to these two areas
  • So, scans have produced objective, reliable, scientific evidence for localisation, allowing the formulation of general laws
  • BUT - involves inferences (that activity means controlling behaviour)

Success of neurosurgery

  • By treating an area where a mental disorder has said to be localised, the mental disorders have reduced
  • E.g. Cingulotomy - OCD said to be localised in the cingulate gyrus region + by isolating it in 44 OCD patients Doughtery found 30% success in treating their OCD
  • Success in treating certain mental disorders by focusing on certain areas supports theory that function is localised
27
Q

Give 2 negative evaluation points for localisation of brain function

A

Gender bias in localisation research

  • Localisation has been criticised for beta bias, as research was only on men + assumed womens’ brains the same
  • Since, research has shown women have a larger Broca’s area + superior language skills
  • So, localisation theory is based on androcentric research + may not be generalisable to everybody (ie. Women)

Alt. theories of equipotentiality + plasticity

  • Equipotentiality = basic motor + sensory functions are localised, but higher cognitive functions are spread across the brain
  • Supported by Lashley - removed 10-15% of rats’ brains + found their ability to learn a route round a maze wasn’t affected by the removal of certain areas, but by the total amount removed
  • Plasticity = after brain damage, functions can be relocated to non-damaged areas
  • Supported by stroke victims
  • So, there is support for the idea that some localisation exists, but it isn’t such a set theory and the brain is able to adapt
28
Q

What does contralateral refer to?

A

The idea that the hemispheres of the brain are ‘cross-wired’ (control the opposite sides of the body)

29
Q

Are all functions lateralised?

A

No

- E.g. sensory representation (somatosensory cortex in both hemispheres)

30
Q

What is split brain research?

A

A series of studies which began in the 1960s and are ongoing, involving people with epilepsy who had experienced treatment involving the surgical separation of their cerebral hemisphere

31
Q

What does split brain surgery do?

A

Severs the corpus callosum

32
Q

What are the effects of split brain surgery?

A
  • Stops large epileptic seizures (severs the connection between the hemispheres so an ‘electrical storm’ cant flow between and cause a seizure)
  • Stops the two hemispheres being able to communicate
33
Q

Who was the most important psychologist who did split brain research?

A

Sperry (1968)

34
Q

What was Sperry’s aim?

A

To test hemispheric lateralisation (extent to which behaviours are controlled by one side of the brain)

35
Q

What was Sperry’s sample?

A
  • 11 ppts (10 men + 1 woman)

- All had split brains after previous epilepsy problems

36
Q

How was Sperry’s split brain research controlled?

A
  • In a lab
  • Any images used only shown for less than 1/10 sec so eyes cant move + one hemisphere is definitely tested at a time
  • Used a control group to compare experimental groups’ performance with (11 people with no epilepsy + ‘normal’ connected brains)
37
Q

Outline Test 1 completed by Sperry + the findings

A

1) Describe what you see
- Images shown to right visual field for <1/10 sec
- Processed by left hemisphere
- Could describe it with words (language in left)

  • Images shown to left visual field for <1/10 sec
  • Processed by right hemisphere
  • Couldn’t describe it with words or said they didn’t see it
  • Could draw it (so did actually see it but can’t use language)

Findings: Language lateralised to left hemisphere

38
Q

Outline Test 2 completed by Sperry + the findings

A

2) Recognition by touch
- Object placed in right hand
- Processed by left hemisphere
- Could describe it with words (language in left)
- Could select it from a grab bag

  • Object placed in left hand
  • Processed by right hemisphere
  • Couldn’t describe it with words
  • Could select it from a grab bag

Findings:

  • Language lateralised to left hemisphere
  • Some capabilities aren’t lateralised (somatosensory)
39
Q

Give 2 evaluation points for hemispheric lateralisation

A

NEG: Plasticity

  • Neural plasticity suggests functions aren’t so fixed (challenges hemispheric lateralisation)
  • Research on patients with damage to one hemisphere has shown functions can be taken over by the other healthy hemisphere
  • E.g. speckles of language in right hem of left stroke patients
  • So, brains may be able to adapt to damage, meaning lateralisation is more fluid than was thought

NEG: Pop psychology

  • Pop psychology has over simplified the theory of lateralisation
  • E.g. quizzes about what ‘sided brain’ you have
  • Although left side is more analytical + right more holistic, they are both important + normally in constant communication
  • So, pop psychology skews the validity of the the theory that is available to the public
40
Q

Give 2 evaluation points for Sperry’s split brain research

A

POS: Some forms of control

  • Standardised + controlled his procedures
  • E.g. lab, images shown for <1/10 sec, control group
  • Increased internal validity (testing hemispheres we want to test) + reliability (easily repeated)
  • Control allows for repetition + formulation of general laws

NEG: Methodological flaws

  • Despite control, some flaws did lower the internal + external validity
  • E.g. lowering internal - control group didn’t have epilepsy too (hard to establish cause-effect with multiple differences between groups)
  • E.g. lowering external - small sample (11) so may not represent whole population
  • These issues lower the validity of the laws formulated
41
Q

Define plasticity

A

The brain’s ability to change and adapt as a result of experience + new learning. This involves the growth of new neural connections.

42
Q

When is the brain most ‘plastic’?

A

During infancy

  • Rapid brain development, making lots of synaptic connections
  • Number of synaptic connections peaks at age 2-3 yrs
43
Q

What was originally believed about neural plasticity in adulthood?

A

Brain fixed by then - no plasticity

44
Q

What is now believed about neural plasticity in adulthood?

A

Brain continues to change
Cognitive pruning - existing connections deleted + strengthened depending on use
Some new connections made - due to new learning + experiences

45
Q

What are pros of having neural plasticity?

A
  • Ability to learn new things
  • Ability to enhance existing cognitive capabilities
  • Ability to maintain functionality after damage (functional recovery)
46
Q

What is a con of having neural plasticity?

A
  • Changes in brain can be bad (e.g. prolonged drug use weakens connections via cognitive pruning, causing poorer cognitive functioning)
47
Q

What research supports plasticity?

A

Maguire - London Taxi Drivers

48
Q

Outline the research + findings completed to support plasticity

A

Maguire - London Taxi Drivers
Research:
- Used MRIs to compare volume of grey matter in the posterior hippocampus of London taxi drivers to a matched pairs control group.
Findings:
- Taxi driver group had on average much higher vol of grey matter in their posterior hippocampus than control group
- The longer their time as a taxi driver, the larger the hippocampus
Conclusions:
- Taxi drivers’ hippocampi enlargen (plasticity) to adapt to their training (for ‘the knowledge’ of streets + routes)

49
Q

What is the posterior hippocampus associated with?

A

Development of spatial + navigational skills

50
Q

Give 3 evaluation points for Maguire’s research on plasticity

A

GOOD - Real world example, high external validity
GOOD - Controlled, objective design increased internal validity (matched control group - reduced individual differences) (used MRI - objective and replicable)

BAD - Can’t confirm cause + effect, didn’t measure hippocampus before, people born with a larger hippocampus may be more likely to be taxi drivers

51
Q

Give a positive evaluation point for plasticity

A

Helpful throughout life

  • Greatest during infancy but doesn’t stop completely
  • Benefits of adapting + changing our brains are gained throughout life
  • E.g. Bezzola - used fMRIs to measure increased motor cortex activity in an experimental group (aged 40-60) who did 40hrs golf training, compared to control group who didn’t
  • Research supports the helpful role of plasticity throughout life
52
Q

Give a negative evaluation point for plasticity

A

Brain can change in a negative way

  • The bran can adapt + change for the worse
  • E.g. Medina et al find brain’s adaption to drug use caused loss of connections, poorer cognitive functioning, higher dementia risk
  • E.g. Phantom limb syndrome - 60-80% of amputees feel pain in lost limb due to remapping of connections in somatosensory cortex
  • Brain’s ability to change + adapt isn’t always positive
53
Q

Define functional recovery

A

A form of plasticity that occurs after brain damage.

The brain adapts + redistributed functions to undamaged areas.

54
Q

What is the difference between plasticity + functional recovery?

A

Plasticity - general ability of brain to change + adapt

Functional recovery - specific change AFTER DAMAGE

55
Q

When does functional recovery occur most quickly?

A

Straight after trauma, then slows

56
Q

When should individuals with brain damage seek rehabilitative therapy?

A

Straight away - recovery is easier then, with more spontaneous recovering happening naturally at this time

57
Q

What happens in functional recovery?

A

Brain forms new synaptic connections
- ‘Unmasks’ secondary, dormant neural pathways in non-damaged areas capable of completing the damaged function
Brain undergoes structural changes
- Axon sprouting
- Reformation of blood vessels
- Recruitment of homologous (similar) areas in opposite hemisphere

58
Q

What is axon sprouting?

A

When new nerve endings grow and connect with undamaged areas to form new pathways

59
Q

Give a positive evaluation point for functional recovery

A

Real-world application

  • Understanding processes involved in functional recovery has helped improve neurorehabilitation
  • E.g. understanding axonal growth has helped with new treatments such as constrained-induced movement therapy (stroke patients encouraged to move affected part + keep other areas still to promote axon sprouting)
  • Also known to start rehabilitation strait away (brain most plastic)
  • So, research into functional recovery has helped medical professionals improve treatment in the real world
60
Q

What is a piece of research that supports plasticity, not done on humans?

A

Lashley’s Rats

  • Removed 10-50% brains
  • Could still navigate maze because undamaged areas compensated
61
Q

Give a negative evaluation point for functional recovery

A

Cognitive reserve

  • Cognitive reserve suggests that the ability of functional recovery is limited by level of education
  • Suggests some uneducated people are less able to recover from brain damage
  • E.g Schneider - 16+yrs education: 40% had disability-free recovery
    - <12 yrs education: 10% had disability-free recovery
  • Suggests education level (linked to socio-economic status) limits success of functional recovery (socially sensitive)