PLASTICITY AND FUNCTIONAL RECOVERY OF THE BRAIN Flashcards
Evaluation Points, Plasticity
> Possible negative behavioural consequences
May not decline sharply with age
Seasonal brain changes
Evaluation Points, Functional Recovery of Brain after Trauma
> Real-world application
Neural plasticity may be related to cognitive reserve
Small samples
PEEL IT: Plasticity, possible negative behavioural consequences
P-One limitation of plasticity is possible negative behavioural consequences
E-The brain’s adaptation to prolonged drug use leads to poorer cognitive functioning in later life, as well as an increased risk of dementia
E-60-80% of amputees have phantom limb syndrome (experience sensations in missing limb due to changes in somatosensory cortex).
L- This suggests that the brain’s ability to adapt to damage is not always beneficial and may lead to physical and psychological problems.
PEEL IT: Plasticity, May not decline sharply with age
P- One strength of plasticity is that it may not decline sharply with age
E- Bezzola et al demonstrated how 40 hours of golf training produced changes in the neural representation in participants aged 40-60
E- Using fMRI, motor cortex activity in the novice golfers increased compared to a control group, suggesting positive effects after training
L-This shows that neural plasticity can continue throughout the lifespan.
PEEL IT: Plasticity, seasonal brain changes
P- An issue with plasticity research is seasonal brain changes
E-Seasonal plasticity occurs in response to environmental changes eg. the suprachiasmatic nucleus (SCN) shrinks in spring and expands in autumn.
E-However, much of the work on seasonal plasticity has been done on animals, most notably songbirds. Human behaviour may be controlled differently
L-This suggests that animal research may be a useful starting point but can’t simply be generalised to humans.
PEEL IT: Functional Recovery after Trauma, real-world application
P-One strength of functional recovery is its real-world application
E-Understanding plasticity has led to neurorehabilitation. Understanding axonal growth encourages new therapies
E-For example, constraint-induced movement therapy involves massed practice with an affected arm while unaffected arm is restrained
L-This shows that research into functional recovery helps medical professionals know when interventions can be made.
PEEL IT: Functional Recovery after Trauma, Neural plasticity may be related to cognitive reserve
P-One limitation is neural plasticity may be related to cognitive reserve.
E-Research has looked at the time brain injury patients had spent in education (indicated by their cognitive reserve) and their chances of a disability-free recovery (DFR)
E-40% of patients who achieved DFR had more than 16 years education compared to about 10% of patients who had less than 12 years education
L-This suggests that cognitive reserve is a cognitive factor in determining how the brain adapts after trauma.
PEEL IT: Functional Recovery after Trauma, Small samples
P-An issue with research into functional recovery after trauma is that it often uses small samples
E-Research on new treatments eg Banerjee et al showed total recovery from stroke using stem cell treatment compared to a normal 4% recovery
E-However this study drew conclusions based on just 5 participants and had no control group, typical of research on functional recovery
L-This research may lack validity, but waiting for larger samples may prevent the development of viable treatments.
Structural changes in the brain whilst recovering from trauma
> Axonal sprouting
Denervation Supersensitivity
Recruitment of homologous (similar areas)
Axonal Sprouting
Growth of new nerve endings which connect with other undamaged cells to form new neuronal pathways.
Denervation Supersensitivity
Axons that do a similar job become aroused to a higher level to compensate for the ones that are lost
Recruitment of homologous (similar) areas
The opposite side of the brain takes over specific tasks eg. language production
Functional Recovery of the brain after trauma
> Healthy brain areas take over functions of areas damaged, destroyed or even missing. Neuroscientists suggest this process occurs quickly after trauma (spontaneous recovery) and then slows down.
The brain is able to rewire and reorganise itself by forming new synaptic connections close to the area of damage
Secondary neural pathways that would not be typically be used to carry out certain functions are activated/’unmasked’ to enable functioning to continue
Structural changes in the brain
Plasticity
> During infancy, the brain experiences rapid growth in synaptic connections, peaking at 15000 at 2-3 years.
As we age rarely used connections are deleted and used connections are strengthened (synaptic pruning), these can continue to be formed at any time due to learning and experience
Draganski et all (2006), imaged the brains of medical students 3 months before and after final exams. Learning-induced changes were seen in posterior hippocampus and the parietal cortex, presumably as result of learning for exam.
Maguire et al (2000)
> Maguire found significantly more volume of grey matter in the posterior hippocampus in London taxi drivers than in a matched control group.
This part of the brain is linked with development of spatial and navigational skills
As part of their training, taxi drivers take a complex test called ‘The Knowledge’ to assess recall of city streets and routes. The experience appears to alter the structure of their brains, the longer they’d been in job the more pronounced it was.
