Localisation Of Brain Function & Plasticity
Strengths : Limitations :
1. Evidence from brain scans supports the idea that 1. Process involved in learning are more holistic
many neurological functions are localised - For example, the work of Karl Lashley
- For example Peterson & Peterson (1988) suggests that higher cognitive functions,
used brain scans to demonstrate how such as processes involved in learning are
Wernicke’s area is active during listening more holistic.
tasks and Broca’s area was active during a - Lashley removed areas of the cortex
reading task, suggesting that these areas (between 10 and 50%) in rats that were
of the brain have different functions. OR learning a maze.
Tulving’s work on memory showed activity - No area was proven to be more important
in hippocampus for episodic LTM & than any other in the rats’ ability to learn
cerebellum for procedural LTM & the maze. The process of learning
Maguire’s research looking at appeared to require every part of the
hippocampus in taxi drivers cortex, rather than a specific area.
- THEREFORE this supports the idea of - This suggests that learning is too complex
brain localisation as each of these 2 to be localised and requires the
different areas of the brain have different involvement of the brain.
- HOWEVER this research was conducted on
functions
rats and so cannot be generalised to
2. There is also earlier evidence from case studies human brains
to support the idea of localisation 2. Localisation of function is undermined by
- For example, Phineas Gage, who in 1848 functional recovery after trauma
while working on a rail line, experienced a - We know that other parts of the brain can
drastic accident in which a piece of iron compensate for damage & in extreme
went through his skull. cases eg EB, the functions of a whole
- Although Gage survived this ordeal, he did hemisphere can be recovered HOWEVER
experience a change in personality, such recovery is rarely perfect & is affected by
as loss of inhibition and anger. age, gender etc)
- This change provided evidence to
support the theory of localisation of brain
function, as it was believed that the area
the iron stake damaged was responsible
for personality.
Split-Brain Research In Hemispheric Brain Lateralisation
Strengths : Limitations :
1. A positive is that the research method developed 1. Additional research has suggested that language
by Sperry, involved highly specialised and may not be restricted to the left hemisphere.
standardised procedures. - For example, Gazzinga (1998) suggests that
- This means that his work has high internal some of the early discoveries from
validity. This method would involve the split-brain research have been
patient staring at a fixation point, whilst
disconfirmed by more recent discoveries.
one eye was being blindfolded.
- The image projected would be flashed up - The case study of JW demonstrated that
for one-tenth of a second, which would the right hemisphere may play some part
prevent them moving their eyes across in language like the left hemisphere as he
both sides of the visual field and developed the capacity to speak out of
subsequently both sides of the brain. the right hemisphere (Turk et al 2002).
- This allowed Sperry to vary aspects of the - This is a weakness because it suggests
basic procedure and ensure that only one that there are inconsistent findings across
hemisphere was receiving information at a split brain research making it difficult to
time. form firm conclusions.
2. A strength of split brain research is that it has led 2. However many researchers have been expressing
to the understanding that brain lateralisation caution about drawing wide spread conclusions
can increase neural processing capacity. from these experiments
- For example, by using only one - Results from using split-brain patients
hemisphere to engage in a particular task may not be generalizable to the
(e.g. language, mathematical ability), this population as a whole.
would leave the other hemisphere free to - Sperry's experiments were conducted on 11
individuals, all with a history of severe
engage in another function.
epilepsy. It is possible that the extent to
- This is a strength because such research which their hemispheres were separated
does provide evidence that brain during the surgery, may also differ.
lateralisation enhances brain efficiency in - The control group that Sperry used had
cognitive tasks that demand the no history of epilepsy and it has been
simultaneous but different use of both argued that this was therefore
hemispheres. inappropriate.
- This therefore highlights that split brain
research has been useful in helping
individuals to understand more clearly the
role of the brain/different hemispheres of
the brain.
Ways of investigating the brain
, Ways of investigating Strengths Limitations
the brain
FMRI 1. Non-invasive 1. Only measures blood flow
- This process does not involve - It doesn’t look at the activity
any insertion of instruments of individual neurons
unlike PET but also doesn’t therefore it’s hard to tell
expose the patient to radiation. exactly what brain activity is
- This is beneficial to the being represented on the
economy as there is no recovery screen
time so people don’t have to be - THEREFORE there is a high
off work but also the patient will likelihood that the findings
not experience any side effects will be misinterpreted as it
from drugs. doesn’t show activity like
2. Has a high spatial resolution EEG/ERP.
- This refers to the smallest
feature that a scanner can 2. Poor temporal resolution
detect. - There is around a 5 second time lag
- A greater spatial resolution between the neuron firing and the
allows psychologists to detect image on screen.
- Therefore is less accurate compared
different areas of the brain with
to EEG
greater accuracy.
- They have a resolution of 1-2mm
which is significantly greater
than other techniques e.g. EEG
EEG 1. Has a good temporal resolution 1. Not highly accurate
- Temporal resolution refers to - When using EEG electrical
the accuracy of the scanner in activity is detected in several
relation to time; or how quickly regions of the brain
the scanner can detect changes simultaneously
in brain activity. - This makes it very hard to
- EEG scanners take readings pinpoint exactly which area
every millisecond, meaning it is producing this activity.
can record the brain’s activity in - THEREFORE cannot
real time. It has been invaluable distinguish differences in
in diagnosing epilepsy, which is activity between 2 closely
characterised by random bursts adjacent areas.
of activity, which can be easily
detected on screen. It has also
contributed to our
understanding of the stages
involved in sleep.
- This suggests EEG has a high
degree of accuracy when
examining brain activity,
allowing psychologists to make
accurate conclusions in relation
to the timing of neural activity.
ERP 1. Brings much more specificity to the 1. Lack of standardisation in
measurement of neural processes, than methodology between studies
could be achieved by using raw EEG
data. - In order to establish pure
- As they are derived from EEGs data, you need to eliminate
they also have excellent all extraneous material and
temporal resolution. this may not always be
- They have been widely used to achievable.
measure cognitive functions - The participant may react to
and deficits.
- Researchers have been able to background noise or a
identify many different types of difference in temperature –
ERP and describe the precise For experiments where these
role of these in cognitive variables can’t be controlled,
functioning it’s difficult to draw
conclusions.
- THEREFORE this makes it
hard to replicate
experiments and confirm
findings in a peer review
study.
Post mortem 1. Improved our medical knowledge 1. The issue of causation
Strengths : Limitations :
1. Evidence from brain scans supports the idea that 1. Process involved in learning are more holistic
many neurological functions are localised - For example, the work of Karl Lashley
- For example Peterson & Peterson (1988) suggests that higher cognitive functions,
used brain scans to demonstrate how such as processes involved in learning are
Wernicke’s area is active during listening more holistic.
tasks and Broca’s area was active during a - Lashley removed areas of the cortex
reading task, suggesting that these areas (between 10 and 50%) in rats that were
of the brain have different functions. OR learning a maze.
Tulving’s work on memory showed activity - No area was proven to be more important
in hippocampus for episodic LTM & than any other in the rats’ ability to learn
cerebellum for procedural LTM & the maze. The process of learning
Maguire’s research looking at appeared to require every part of the
hippocampus in taxi drivers cortex, rather than a specific area.
- THEREFORE this supports the idea of - This suggests that learning is too complex
brain localisation as each of these 2 to be localised and requires the
different areas of the brain have different involvement of the brain.
- HOWEVER this research was conducted on
functions
rats and so cannot be generalised to
2. There is also earlier evidence from case studies human brains
to support the idea of localisation 2. Localisation of function is undermined by
- For example, Phineas Gage, who in 1848 functional recovery after trauma
while working on a rail line, experienced a - We know that other parts of the brain can
drastic accident in which a piece of iron compensate for damage & in extreme
went through his skull. cases eg EB, the functions of a whole
- Although Gage survived this ordeal, he did hemisphere can be recovered HOWEVER
experience a change in personality, such recovery is rarely perfect & is affected by
as loss of inhibition and anger. age, gender etc)
- This change provided evidence to
support the theory of localisation of brain
function, as it was believed that the area
the iron stake damaged was responsible
for personality.
Split-Brain Research In Hemispheric Brain Lateralisation
Strengths : Limitations :
1. A positive is that the research method developed 1. Additional research has suggested that language
by Sperry, involved highly specialised and may not be restricted to the left hemisphere.
standardised procedures. - For example, Gazzinga (1998) suggests that
- This means that his work has high internal some of the early discoveries from
validity. This method would involve the split-brain research have been
patient staring at a fixation point, whilst
disconfirmed by more recent discoveries.
one eye was being blindfolded.
- The image projected would be flashed up - The case study of JW demonstrated that
for one-tenth of a second, which would the right hemisphere may play some part
prevent them moving their eyes across in language like the left hemisphere as he
both sides of the visual field and developed the capacity to speak out of
subsequently both sides of the brain. the right hemisphere (Turk et al 2002).
- This allowed Sperry to vary aspects of the - This is a weakness because it suggests
basic procedure and ensure that only one that there are inconsistent findings across
hemisphere was receiving information at a split brain research making it difficult to
time. form firm conclusions.
2. A strength of split brain research is that it has led 2. However many researchers have been expressing
to the understanding that brain lateralisation caution about drawing wide spread conclusions
can increase neural processing capacity. from these experiments
- For example, by using only one - Results from using split-brain patients
hemisphere to engage in a particular task may not be generalizable to the
(e.g. language, mathematical ability), this population as a whole.
would leave the other hemisphere free to - Sperry's experiments were conducted on 11
individuals, all with a history of severe
engage in another function.
epilepsy. It is possible that the extent to
- This is a strength because such research which their hemispheres were separated
does provide evidence that brain during the surgery, may also differ.
lateralisation enhances brain efficiency in - The control group that Sperry used had
cognitive tasks that demand the no history of epilepsy and it has been
simultaneous but different use of both argued that this was therefore
hemispheres. inappropriate.
- This therefore highlights that split brain
research has been useful in helping
individuals to understand more clearly the
role of the brain/different hemispheres of
the brain.
Ways of investigating the brain
, Ways of investigating Strengths Limitations
the brain
FMRI 1. Non-invasive 1. Only measures blood flow
- This process does not involve - It doesn’t look at the activity
any insertion of instruments of individual neurons
unlike PET but also doesn’t therefore it’s hard to tell
expose the patient to radiation. exactly what brain activity is
- This is beneficial to the being represented on the
economy as there is no recovery screen
time so people don’t have to be - THEREFORE there is a high
off work but also the patient will likelihood that the findings
not experience any side effects will be misinterpreted as it
from drugs. doesn’t show activity like
2. Has a high spatial resolution EEG/ERP.
- This refers to the smallest
feature that a scanner can 2. Poor temporal resolution
detect. - There is around a 5 second time lag
- A greater spatial resolution between the neuron firing and the
allows psychologists to detect image on screen.
- Therefore is less accurate compared
different areas of the brain with
to EEG
greater accuracy.
- They have a resolution of 1-2mm
which is significantly greater
than other techniques e.g. EEG
EEG 1. Has a good temporal resolution 1. Not highly accurate
- Temporal resolution refers to - When using EEG electrical
the accuracy of the scanner in activity is detected in several
relation to time; or how quickly regions of the brain
the scanner can detect changes simultaneously
in brain activity. - This makes it very hard to
- EEG scanners take readings pinpoint exactly which area
every millisecond, meaning it is producing this activity.
can record the brain’s activity in - THEREFORE cannot
real time. It has been invaluable distinguish differences in
in diagnosing epilepsy, which is activity between 2 closely
characterised by random bursts adjacent areas.
of activity, which can be easily
detected on screen. It has also
contributed to our
understanding of the stages
involved in sleep.
- This suggests EEG has a high
degree of accuracy when
examining brain activity,
allowing psychologists to make
accurate conclusions in relation
to the timing of neural activity.
ERP 1. Brings much more specificity to the 1. Lack of standardisation in
measurement of neural processes, than methodology between studies
could be achieved by using raw EEG
data. - In order to establish pure
- As they are derived from EEGs data, you need to eliminate
they also have excellent all extraneous material and
temporal resolution. this may not always be
- They have been widely used to achievable.
measure cognitive functions - The participant may react to
and deficits.
- Researchers have been able to background noise or a
identify many different types of difference in temperature –
ERP and describe the precise For experiments where these
role of these in cognitive variables can’t be controlled,
functioning it’s difficult to draw
conclusions.
- THEREFORE this makes it
hard to replicate
experiments and confirm
findings in a peer review
study.
Post mortem 1. Improved our medical knowledge 1. The issue of causation
