localisation of function Flashcards
1
Q
what is localisation of function?
A
- theory that different areas of the brain are responsible for specific processes or activities
- if a certain area of the brain becomes damaged through illness or injury, the function associated with that area will also be affected
2
Q
how is the cerebrum divided?
A
2 symmetrical halves called the left and right hemisphere
3
Q
what is lateralisation?
A
the idea that some of our physical and psychological functions are controlled or dominated by a particular hemisphere
4
Q
what is activity on the left or right-hand side of the body controlled by?
A
- activity on the left-hand side of the body is controlled by the right hemisphere
- activity on the right-hand side of the body is controlled by the left hemisphere
5
Q
what is the cortex of both hemispheres divided into?
A
4 centres called lobes
6
Q
what are the four lobes of the brain?
A
- the frontal lobe
- the parietal lobe
- the occipital lobe
- the temporal lobe
7
Q
what is a lobe?
A
- a part of an organ that is separate in some way from the rest
- each lobe in the brain is associated with different functions
8
Q
describe the motor area
A
- back of frontal lobe in both hemispheres
- controls voluntary movement in opposite side of body
9
Q
what might damage to the motor area result in?
A
loss of control over fine movements
10
Q
describe the somatosensory area
A
- at the front of both parietal lobes
- separated from the motor area by a ‘valley’ called the central sulcus
- where sensory information from the skin (eg. related to touch, heat, pressure etc.) is represented
- the amount of SA devoted to a particular body part denotes its sensitivity
> eg. receptors for our hands and face occupy over half of the area
11
Q
describe the visual area
A
- in the occipital lobe at the back of the brain
- each eye sends information from the RVF to the left visual cortex and vice versa
- therefore, damage to the LH can produce blindness in part of the RVF in both eyes
12
Q
describe the auditory area
A
- in the temporal lobes
- analyses speech-based information
13
Q
what may damage to the temporal lobe result in?
A
- partial hearing loss
- the more extensive the damage, the more extensive the loss
- damage to a specific area of the temporal lobe, wernicke’s area, may affect the ability to comprehend language
14
Q
describe broca’s area
A
a small area in the left frontal lobe responsible for speech production
15
Q
what does damage to broca’s area result in and describe the condition
A
- broca’s aphasia
- characterised by speech that is slow, laborious and lacking in fluency
- difficulty with prepositions and conjuctions (a, the and etc.)
16
Q
describe broca’s most famous patient
A
- ‘tan’
- this was the only word he could say
17
Q
describe wernicke’s area
A
region in the left temporal lobe which is responsible for language understanding
18
Q
describe wernicke’s aphasia
A
- caused when wernicke’s area is damaged
- can produce language but severe difficulties understanding it
- the speech they produce is fluent but meaningless
- produce nonsense words (neologisms) as part of the content of their speech
19
Q
evaluation: evidence from neurosurgery
A
- damage to areas of the brain has been linked to mental disorders
- neurosurgery is a last resort method for treating some mental disorders, targeting specific areas of the brain
- eg. cingulotomy involves isolating a region of called the cingulate gyrus, which has been implicated in OCD
- dougherty et al. (2002) reported on 44 people with OCD who had undergone a cingulotomy
- at post-surgical follow-up after 32 weeks, about 30% had met the criteria for successful response to the surgery and 14% for partial response
- the success of these procedures suggests that behaviours associated with serious mental disorders may be localised
20
Q
evaluation: evidence from brain scans supports the idea that many everyday brain functions are localised
A
- petersen et al. (1988) used brain scans to demonstrate how wernicke’s area was active during a listening task and broca’s area was active during a reading task
- a review of long-term memory studies (buckner and petersen 1996) revealsed that semantic and episodic memories reside in different parts of the prefrontal cortex
- these studies confirmed localised areas for everyday behaviours
- therefore, objective methods for measuring brain activity have provided sound scientific evidence that many brain functions are localised
21
Q
evaluation: challenge to localisation theory from lashley (1950)
A
- lashley removed areas of the cortex (between 10-50%) in rats that were learning the route through a maze
- no area was proven to be more important than any other area in terms of the rats’ ability to learn the route
- the process of learning seemed to require every part of the cortex rather than being confined to a particular area
- this suggests that higher cognitive processes, such as learning, are not localised, but distributed in a more holistic way in the brain
22
Q
evaluation: language may not be localised to just broca’s and wernicke’s areas
A
- review by dick and tremblay (2016) found that only 2% of modern researchers think that language in the brain is completely controlled by broca’s and wernicke’s areas
- advances in brain imaging technqiues, such as fMRI, mean that neural processes in the brain can be studied with more clarity than every before
- language function seems to be distributed far more holistically in the brain than was first thought
- language streams have been identified across the cortex, including brain regions in the right hemisphere, as well as subcortical regions such as the thalamus
- this suggests that, rather than being confined to a couple of key areas, language may be organised more holistically in the brain, which contradicts localisation theory
23
Q
evaluation: case study evidence
A
- unique cases of neurological gamage support localisation theory, such as the case of phineas gage
- however, there are problems with case studies as it is difficult to make meaningful generalisations from the findings of a single individual
- also, conclusions drawn may depend on the subjective interpretation of the researcher
24
Q
evaluation: phineas gage (1848)
A
- a metre-long pole was hurled through his left cheek during an explosion, passing behind his left eye and exiting his skull from the top of his head taking more of his left frontal lobe with it
- the damage to his brain had left a mark on his personality
- he turned from someone who has calm and reserved to someone who was quick-tempered and rude
- the change in temperament following the accident suggested that the frontal lobe may be responsible for regulating mood
25
Q
evaluation: harasty (1997)
A
- found that women have proportionately larger wernicke and broca’s areas, resulting in women’s greater use of language
- this supports the idea of localisation of function, but suggests invidiual differences
- it suggests that male and female brains operate in a different manner and doesn’t follow the initial theories of the brain as suggested by early research
26
Q
evaluation: bavelier et al. (2011)
A
- found that when completing silent reading, different parts of the brain were active (eg. occipital or temporal)
- study shows the variability in the patterns of activation across the brain
- this contradicts the notion that specific areas are for specific functions in the brain
27
Q
evaluation: saygin et al. (2003)
A
- found that some patients displayed symptoms of wernick’es aphasia without any damage to this area
- this raises questions regarding the exact nature of wernicke’s area, and the ability to assign singular functions to brain regions and / or singular regions to complex functions
