Plasticity and Functional Recovery of the brain after trauma Flashcards
(17 cards)
what is brain plasticty?
the idea that the brain has the ability to change throughout life, as a result of experiences and learning
what happens to the brain during infancy?
- the brain experiences rapid growth in the number of synaptic connections it has
- peaking at 15,000 neurons at age 2-3 years (Gopnik et al)
what is synaptic pruning?
as we age:
- the rarely used connections are deleted
- frequently used connections are strengthened
what does synaptic pruning enable?
- lifelong plasticity
- new neural connections form in response to new demands of the brain
who are the researchers involved in the research of synaptic pruning?
- Maguire et al
- Draganski et al
what did Maguire et al find?
- studied the brains of London taxi drivers and found significantly more volume of grey matter in the posterior hippocampus than the matched control group
- the longer taxi driver had been in job the more pronounced the structural difference = positive correlation
why did Maguire et al find these findings?
- as a part of training the London cab drivers have to take a test called the Knowledge test
- this learning experiences alters the brain structure of the taxi drivers
what did Draganski find?
- imaged brains of medical students three months before and three months after the final exam
- learning induced changes occurred in the posterior hippocampus and parietal cortex
what is functional recovery?
- a form of plasticity where following brain trauma, the brain can transfer the functions usually performed by damaged areas to healthy areas
what do neuroscientists say about functional recovery?
- happens quickly after the trauma = spontaneous recovery
- slows down after several weeks or months
- at time point the individual may require rehabilitative therapy
how is the brain able to rewire itself?
by forming new synaptic connections close the the area of damage
- secondary neural pathways which aren’t usually used to carry out certain functions and activated and unmasked
during functional recovery what are the structural changes to the brain that may occur?
- axonal sprouting
- denervation supersensitivity
- recruitment of homologous areas in the opposite side of the brain
what is axonal sprouting?
- the growth of new nerve endings which connect with other undamaged nerve cells to form neuronal pathways
what is denervation supersensitivity?
- axons that have a similar job are aroused to a higher level to compensate for the ones which are lost
- can have a negative consequence of oversensitivity to messages such as pain
what is the recruitment of homologous areas of the opposite side of the brain?
- specific tasks can still be performed
- e.g. if Broca’s area was damaged on the left side of the brain = right sided equivalent would still carry out its functions
- after a period of time functionality may shift back to the left side
wha are the evaluations of plasticity?
Point: A limitation of plasticity is that it may have negative behavioural consequences
Evidence: For example, research shows estimates that 60-80% of amputees have developed phantom limb syndrome, where they continue to experience sensations of the missing limbs.
Explain: This is due to the cortical reorganisation in the somatosensory cortex, following the loss of a limb, and leads to unpleasant sensations.
Link: Therefore, this seems to suggest that the brain’s ability to adapt to damage might not always be beneficial.
Point: A strength of plasticity is that it may be a life-long ability of the brain.
Evidence: Bezzola (2012) has shown that 40 hours of golf training resulted in changes in the brain associated with movement in participants aged 40-60.
Explain: This means that the researchers, using fMRI, were able to measure increased motor cortex activity in the novice golfers compared to a control group.
Link: Therefore, this suggests that brain plasticity continues throughout a person’s lifespan.
what are evaluations of functional recovery?
+ real world applications: understanding the principles of plasticity has contributed to the field of neurorehabilitation. For example by simply understanding that axonal sprouting is possible has lead to new therapies being tested. For example constrained-induced movement therapy which is used for stroke patients whereby they repeatedly practice using the affected part of the body whilst the unaffected part is restrained
- level of education may influence the recovery rates: Schneider et al found that the more time spent in education(indicated by their cognitive reserve) the greater the chance of disability-free recover(DFR). 40% of people who achieved DFR had spend more than 16 years in educations compared to 10% who had spent less than 12 years in education
