Plasticity and Functional Recovery of the brain

• Plasticity 


  the brain's tendency to change and adapt due to experience and new learning. Generally involving the growth of new connections.
• Functional Recovery


  A form of plasticity following damage through trauma, the brains ability to redistribute or transfer functions usually performed by a damaged area to other undamaged areas. It is suggested this happens quickly after trauma and slows over weeks to months. After they may require rehabilitative therapy to further recovery.
• Plasticity through aging


  During infancy the brain experiences rapid growth in number of synaptic connections, peaking at approximately 15000 at 2-3 yrs. About twice as many as there are in the adult brain. As we age, connections that are barely used are deleted and frequently used ones are strengthened (synaptic pruning). People once thought the adult brain was incapable of change but synaptic pruning allows for lifelong plasticity, where new connections form in response to new demands.
• Taxi study on plasticity

  Maguire et al (2009) studied the brain the brains of London taxi drivers and found significantly more volume of grey matter in the posterior hippocampus than in a matched control group. This part of the brain is associated with the development of spatial and navigational skills in humans and other animals. London cabbies must take a complex test that recalls their memory of city streets and possible routes. He found this alters the structure of their brains. The longer they had been working the more the structural difference (positive correlation)
• Draganski plasticity study


  Dranganski (2006) imaged the brains of medical students before and after their final exams. earning-induced changes were seen to have occurred in the posterior hippocampus and the parietal cortex presumably as a result of learning.
• Process of functional recovery


  The brain can rewire and reorganise close to the area of damage. Secondary neural pathways that would not typically be used to carry out certain functions are activated to enable functioning to continue. This is supported by a number of structural changes in the brain.
• Structural changes involved in functional recovery

  Axonal Sprouting- growth of new nerve endings which connect other undamaged nerve cells to form new neural pathways

  Denervation hypersensitivity- when axons do a similar job and become aroused to a higher level to compensate for one's lost. It can, however, cause over-sensitivity to things like pain.

  Recruitment of homologous (similar) areas on the opposite side of the brain. Meaning specific tasks can still be performed. E.g. If Brocas is damaged, the equivalent on the right hemisphere would be activated. This may shift back over time.
• Negative Plasticity


  A negative of plasticity is it may have negative consequences. Evidence has shown the brain's adaptation to prolonged drug use, leads to poor functioning later in life and increased risk of dementia. 60-80% of amputees develop phantom limb syndrome, which is usually unpleasant, and painful and thought to be due to cortical recognition in the somatosensory cortex, which occurs as a result of limb loss. This suggests that the brain's ability to adapt to damage is not always beneficial.
• Age and Plasticity (strength)


  One strength of plasticity is that it does not always decline sharply with age, however, Bezzola et al (2012) demonstrated how 40 hours of golf training produced changes in neural connections of movement in participants 40-60 yrs. Using fMRI, the researchers observed increased motor cortex activity in the novice golfers compared to a control group, suggesting more efficient neural connections after training. Showing neural plasticity can continue throughout the lifespan.
• Seasonal Plasticity


  Research suggests there may be seasonal plasticity in the brain in response to environmental changes. For example, consider the supercharacteristic nucleus (SCN) seen to shrink in animals during spring and expand during autumn. However much of the work on seasonal plasticity has been done on animals, notably songbirds. Human behaviour may be controlled differently.
• Real-work application of functional recovery


  A strength of functional plasticity research is its real-world application. Understanding has contributed to the field of neurorehabilitation. Understanding axonal growth encourages new therapies to be tried. E.g. constraint-induced movement therapy for stoke patients, repeatedly practising movements using the affected body parts while the unaffected parts are restrained. Showing how functional recovery research helps professionals to know when interventions need to be made.
• Educations effect on functional recovery


  A limitation of functional recovery is that the level of education may affect recovery rates. Schnieder (2014) found the more time people with brain injuries had spent in education, the greater their chance of a disability-free recovery. 40% of those who achieved a disability free-recovery, had more than 16 years, compared to 10% of those who had less than 12 years. This would imply that people with brain damage who are less educated are less likely to achieve a disability-free, full recovery.