plasticity and functional recovery of the brain after trauma Flashcards
plasticity
the brains tendency to change or adapt because of experience and new learning
- this generally involves the growth of new connections
when does growth of synaptic connections peak
at around 2-3
what happens to nerve pathways that are used frequently
stronger connections are developed
what happens to nerve pathways that are rarely used
they eventually die
synaptic pruning
pruning away weak synaptic connections and developing new connections to adapt to a changing environment
is plasticity lifelong
yes, synaptic pruning allows for lifelong plasticity where new neural connections are formed in response to new demands on the brain
natural decline in cognitive functioning
age means that cognitive functioning naturally declines over time
whats the supporting study for plasticity
maguire
aim of maguire
To investigate whether changes in the brain could be detected because of
extensive experience of spatial navigation.
method of maguire
The sample consisted of 16 male London taxi drivers and 50 males who did
not drive taxis (control group). Using an MRI scanner, the researchers
calculated the amount of grey matter in the brains of taxi drivers and a set
of control participants.
findings of maguire
- The first finding was that the posterior hippocampus of taxi
drivers was significantly larger relative to those of control participants. This part of the brain is associated with spatial and navigational skills in humans and animals. - The second finding was that the posterior hippocampal volume was positively correlated with the amount of time they had spent as a taxi driver (a measure of the extent of their experience).
conclusion of maguires study
The brain changes physically because of experience (plasticity of the brain)
MRI scan - empirical
- strength of Maguire’s research is that it is highly empirical.
- Brain scans provide objective evidence to show that the cab drivers she studied did
indeed have a significantly greater volume of grey matter in the posterior hippocampus
than did a matched control group. - This is a strength because these findings provide verifiable evidence for brain plasticity and
so suggests that the conclusions drawn about brain plasticity are valid.
correlational data
- An issue with Maguire’s evidence is that it is only correlational.
- This means that she has not proven that the taxi driver’s brains have changed as a direct result of their experience – it might be due to some other factor.
- However, the correlation between their occupation and enhanced grey matter was very clear which suggests that, despite only being correlational, Maguire’s evidence is valid.
low population validity
- An issue with Maguire’s research is that she only used a small sample of 16 male London taxi drivers.
- It is possible that this group of participants is not representative of the population from which they were drawn.
- This means that Maguire’s conclusion that the brain changes physically as a result of
experience may not be valid. - However, there is no evidence to suggest that her sample was
unrepresentative which suggests that a lack of population validity is not really an issue in this
case. - However, since the sample only consisted of males it is possible that the findings may not be applicable to females.
age and plasticity
- There is evidence to support the claim that plasticity does not inevitably decline sharply with
age. - Ladina Bezzola et al demonstrated how 40 hours of golf training produced changes in the neural representations of movement in participants aged 40-60. Using fMRI scans,
researchers observed increased motor cortex activity in the novice golfers compared to a
control group, suggesting more efficient neural representations after training. - This demonstrates that neural plasticity can continue throughout the lifespan.
functional recovery
a form of plasticity following damage through trauma the brains ability to distribute or transfer functions usually performed by a damaged area to other undamaged areas
does functional recovery last
- occurs quickly after trauma (spontaneous recovery)
- slows down after several weeks and rehabilitation therapy may be needed to further recovery
what happens to the brain during recovery
- new synaptic connections formed close to the area of damaged
- secondary neuronal pathways that wouldnt normally be used are activated to enable functioning to continue
what 3 things happen in the brain
- axonal spouting
- denervation super sensitivity
- recruitment of homologous areas on the opposite side of the brain
axonal spouting
the growth of new nerve endings which connect with other undamaged nerve cells to form new neuronal pathways
denervation super sensitivity
axons that do a similar job become aroused to a higher level to compensate for the one that are lost
what is an issue with denervation super sensitivity
nerves can become oversensitive to messages relating to pain
recruitment of homologous areas on the opposite side of the brain
meaning specific tasks can still be performed
- eg if brocas area was damaged on the left side of the brain the right side equivalent may carry out its functions
- functionality may then shift back to the left side
what study provides supporting evidence for functional recovery
danelli
danelli aim
To investigate if the brain can functionally recover after trauma by redistributing functions
normally performed by the damaged area to other undamaged areas.
danelli method
EB was operated on at the age of two and a half to remove a large tumour from his left
hemisphere. Due to the size of the tumour virtually the entire left hemisphere was removed, and, at the time, all his linguistic abilities disappeared. He then underwent a long rehabilitation
programme to recover his language skills.
danelli results
His language abilities started to improve at around the age of 5. When tested again at the age of
17 to compare his language abilities with ‘normal’ controls Danelli et.al. found that his right
hemisphere had compensated for the loss of the left hemisphere and that he was functioning well linguistically. However, they did find some areas which were not to the expected standard e.g.,
minor grammatical errors and lack of speed when asked to name objects in pictures.
danelli conclusion
They concluded that hemispheric lateralisation can be compensated for to at least a basic degree by the non-specialist hemisphere.
case study
P Case studies of individuals are, by their very nature, unrepresentative. This is because there is
no certainty that they are typical of the population from which they are drawn.
E Consequently, we cannot be certain that the functional brain recovery demonstrated by EB
would occur in other human beings – older people in particular.
E This study therefore does not prove that functional recovery is possible.
L However, there is no evidence to suggest that EB is unrepresentative and hence the study of
Danelli et.al. provides reasonable evidence in support of this theory.
practical application of functional recovery
P One strength of functional recovery is its real-world application. Understanding the processes involved in plasticity has contributed to the field of neurorehabilitation.
E Following illness of injury to the brain spontaneous recovery tends to slow down after a
number of weeks so forms of physical therapy (such as electrical stimulation of the brain) may be required in order to maintain improvements in functioning.
E The success of such therapies (based as they are on research into plasticity) suggests that the
theory, and the research underpinning it, are valid. It also shows that research into functional recovery is useful because it helps medical professionals know when interventions need to be
made.
L However, it also shows that, even though the brain may have the capacity to ‘fix’ itself to some
extent, this process requires further intervention if it is to be completely successful.
