4.2.2 LOCALISATION OF FUNCTION IN THE BRAIN AND HEMISPHERIC LATERALISATION (FUNCTIONAL RECOVERY) Flashcards

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1
Q

what is the cerebrum?

A
  • largest part of the brain, divides into 4 lobes which all have a different function
  • splits down the middle into 2 hemispheres
    -> each has different specialisms (eg. left for language)
  • hemispheres communicate using the corpus callosum
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2
Q

what is the cerebellum?

A
  • sits at the back of the cerebrum
  • controls motor skills and balance and coordination
  • coordinates muscles to allow for precise movement
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3
Q

what is the brain stem?

A
  • regulates essential functions for life
  • breathing, heartbeat, swallowing
  • involves involuntary responses
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4
Q

what are two types of brain wrinkles?

A

1) gyrus
- the hills in the brain

2) sulcus
- the valleys in the brain (wrinkles)

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5
Q

what did scientists believe about science?

A

1) scientists believed the brain was holistic in its processing
- ie) all parts are involved in cognition

2) in 19th century, a new kind of thinking emerged
- what if different parts of the brain had performed different tasks / were associated to different places in the body

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6
Q

what is localisation?

A

the theory that specific areas of the brain are associated with particular physical and psychological functions

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7
Q

what happened to Phineas Gage?

A
  • there was an explosion where the tamping iron went straight through his skull
  • it was 3ft 8inches long / weighing 6kg
  • he was walking, talking, sat upright
    -> he threw up + this action caused some of his brain to fall out
  • the pre-frontal cortex is involved with personality and he damaged this
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8
Q

what happened during Phineas Gage’s recovery?

A
  • his brain was left uncovered during treatment and got infected
    -> he was then in an unconscious state until recovered
  • his employers couldn’t give him his job back as he was so different
    -> ie) rude / swears / doesn’t care about offending others / he’ll ignore you if he doesn’t want to follow your order
  • his friends said he was ‘no longer Gage’
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9
Q

what does Phineas Gage’s case study support?

A

the idea of localisation, and the personality change can be explained by the damage to a specific area of the brain

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10
Q

both hemispheres have 4 brain lobes?

A

1) frontal lobe

2) temporal lobe

3) partial lobe

4) occipital lobe

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11
Q

what does the frontal lobe do?

A

responsible for emotion, decision making and organisation

  • motor control (premotor cortex)
  • problem solving (prefrontal cortex)
  • speech production (Broca’s area)
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12
Q

what does the temporal lobe do?

A

responsible for:
- long term memory
- identifying and naming objects
- auditory processing
- language comprehension (Wernicke’s area)

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13
Q

what does the parietal lobe do?

A

responsible for processing sensory information and spatial awareness

  • touch perception (somatosensory cortex)
  • body orientation
  • sensory input
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14
Q

what does the occipital lobe do?

A

responsible for processing visual information

  • sight (visual cortex)
  • visual reception and interpretation
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15
Q

where is the motor area
what does it do
what happens if damage is caused to it?

A
  • at the back of the frontal lobe (both hemispheres)
  • controls voluntary movement
  • each hemisphere controls the opposite side of the body
  • damage to this area could lead to loss of fine motor movements
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16
Q

where is the auditory area
what can damage to it cause?

A
  • located in temporal lobes (nearest ears)
  • damage can lead to hearing loss / difficulty understanding what you’re hearing
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17
Q

where is the somatosensory area
what does it do?

A
  • at front of both parietal lobes
  • sensory info from the skin is represented there
  • amount of somatosensory area devoted to each body part devotes sensitivity
    -> eg) our hands + feet take up over 1/2 of the area
  • is separated from the motor area by a ‘valley’ (deep wrinkle) called the central sulcus
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18
Q

what is lateralisation?

A
  • cerebrum is divided into 2 hemispheres
    -> left and right
  • each hemisphere is responsible for some specific functions
  • = the dominance of one hemisphere of the brain for particular physical and psychological functions
19
Q

where are the language centres of the brain?

A
  • tends to be on the left side of the brain for most ppl
20
Q

the brain is contralateral - what does this mean?

A
  • the left side of the body is controlled by the right side of the brain and vice versa
  • if someone has a stroke in the left side of their brain, it will be physically evident on the right side of the body
21
Q

what is the right hemisphere responsible for?

A
  • dominant in recognising emotions in others
  • spatial information
  • facial recognition
  • drawing
  • viewing objects in the left visual field
  • controls left side of the body

-> known as minor hemisphere as it can’t process language

22
Q

what is the optic chiam?

A

where the visual pathways cross over

23
Q

what is the left half of the brain specialised for?

A
  • controls right side of the body
  • viewing objects in the right visual field
  • known as the major hemisphere as it processes language
24
Q

what is Broca’s area?

A
  • Broca correctly identified the area of the brain responsible for speech
  • they found not all words were equal in the Broca area and they were effected differently
  • nouns + verbs seemed to be less effected but predisposition and conjunctions were no longer able to be used
25
Q

who was Broca and how did he discover Broca’s area?

A
  • was a neurologist
  • one patient, Louis Lebornge (son of school teacher) suffered from epilepsy through childhood
  • he was educated and a craftsman, but eventually lost the ability to speak
  • Broca performed a post-morgen study on his brain
  • found a lesion on the left temporal lobe
  • Broca concluded this area was responsible for speech production as it was the only area of damage
26
Q

what does Broca’s aphasia mean?

A

used today for patients who display problems producing speech

27
Q

what is Wernickes Area?

A
  • separate area of language processing which has a specific function
  • Wernicke worked in a hospital in Germany
    -> found patients who had damage near the auditory cortex had specific language impairments
    -> inability to comprehend language and anomia
  • but found that the same ppl had fluent speech when they were able to access words quickly
  • mans suggested this area was important for understanding language and accessing words
28
Q

label this diagram of the brain

A
29
Q

what did Roger Sperry do want to do?

A

investigate what would happen if our hemispheres weren’t connected
and whether they perform different functions

30
Q

what was Sperry’s procedure?

A
  • studied 11 patients who had a corpus callosotomy as treatment for their epileptic seizures
  • the subjects gazes at a fixation point on an upright translucent screen where Sperry projected info into each visual field
  • slides containing words / images are projected either side of the fixation point for 1/10th of a second
  • in a series of test, ppts were asked to either say what they saw, draw it or pick it out from hidden objects
31
Q

what did Sperry find?

A
  • info presented to the left hemisphere could be spoken but not if it had been delivered to the right hemisphere
  • info presented to the right hemisphere could be drawn or picked out from objects with left hand
32
Q

the right hemisphere dominates when matching faces
how do we know this?

A
  • because when faces are shown to LVF, it’s sent to the right hemisphere, the correct matching picture is selected
  • when shown to the RVF, it’s sent to the left hemisphere and the matching. picture isn’t selected
33
Q

what happens when using a composite picture (where each hemisphere sees half a face)?

A
  • if RVF to left hemisphere, a verbal description can be given
  • if LVF to right hemisphere, can select a matching picture
34
Q

what is a commissurotomy?

A

the division of the two hemispheres by surgery

35
Q

what can we conclude from Sperry’s study?

A
  • when we separate the hemispheres we can clearly see that they act differently
  • the right hemisphere can recall and identify stimuli but cannot verbalise this
  • the left hemisphere is specialised for speech and writing
  • right hemisphere is mute and can’t speak or write
    -> can’t speak = aphasic
    -> can’t write = agraphic
36
Q

what are three negatives to Sperry’s study?

A

1) Sperry’s original ppts were epileptic
- can’t be said to represent normal brains
- their brains may somehow be different due to the epilepsy
- the control group (not spilt brain) weren’t epileptic

2) small sample size
- Sperry used 11 spilt brain ppts
- some ppl have more lateralised brains than others
- some ppl had more disconnection of the two hemispheres than others
-> this may mean that individual differences could influence results

3) sex differences
- although his work concluded that many functions are lateralised, subsequent work suggests that women have less lateralised brains
- this will influence the result of brain damage
- eg) Kimura reported more aphasia in men who had left hemisphere damage than women with it too

37
Q

what’s a strength of Sperry’s study?

A

1) despite these criticisms
- Sperry created a well controlled and replicable standardised procedure
- (asking ppts to stare at a fixed central point and presenting stimuli only briefly ensured each hemisphere received info from only one visual field)

  • has triggered a philosophical debate about the value of the mind
    -> are our 2 hemispheres so functionally different that they can be considered as two minds?
38
Q

what does plasticity mean?

A

the brains apparent ability to change and adapt both physically and functionally

39
Q

what happens to the brain during recovery?

A

1) axonal sprouting
- the growth of new nerve ending which connect with other undamaged nerve cells to form new neural pathways

2) reformation of blood vessels

3) recruitment of homologous areas
- when a homologous (similar) area of the brain on the opposite side is used to perform a specific task

40
Q

what did Maguire at al do and find?

A
  • conducted structural MRI scans on 16 male London taxi drivers were compared with 16 male matched (same age, education etc) non-taxi drivers
  • found posterior hippocampi in London cab drivers were significantly larger than the control group of non cab drivers
  • found size of posterior hippocampi was reflective on how long they’d been a cab driver
  • his research suggests the brain is plastic and able to configure itself to its environment and psychological demands
41
Q

what did Danielli et al do and find?

A
  • case study of EB who was 14yrs old
  • at 2yrs old, EB had a hemispherectomy on left side of his brain to remove a tumour
  • his language centres were removed, including Broca and Wernicke
  • immediately after surgery, he’d lost all language function
    -> but after 2yrs, he’s recovered his language ability without his left hemisphere
  • this supports brain plasticity, showing the brain can adapt and recover after trauma, especially early on in life
  • researcgers completed fMRI scans and found the right hemisphere acted as it was the left, for language
42
Q

what are two strengths of both Danielli and Maguire?

A

1) negative plasticity
- brains ability to rewire itself can sometimes have maladaptive behavioural consequences
- maladaptation itself isn’t a strength, but examples of it support the notion of the brain’s plasticity
- Medina et al found prolonged use of marijuana resulted in poorer cognitive functioning + increased risk to dementia

2) practical application
- used in real world + supports patients with changes / damage to brain
- contributed to the field of neurorehabilitation
- spontaneous recovery tends to slow down after a few weeks so physical therapy may be needed to maintain improvements in functioning
- eg) movement therapy, electrical stimulation to counter deficits in motor +/or cognitive functioning after stroke eg

43
Q

what’s a negative of these studies into brain plasticity?

A