Plasticity

• How is the brain plastic


  It can change throughout life
• How many synaptic connections are in a 2/3yr old brain

  15,000
• Synaptic pruning def


  As we get older, synaptic connections we don't use are detected & ones we use frequently are strengthened
• What did people believe before synaptic pruning

  After a critical period, the structure & function of brain will remain fixed
• How can new synaptic connection be made

  Through learning and experience
• What is some evidence supporting plasticity

  Stroke victims, who have experienced brain damage (thus lost brain functions) have shown the brain has the ability to rewire itself. The undamaged brain sites took over the function sof the damaged brain sites.
• What did Kuhn find (plasticity)

  Found significant increase in grey matter in various regions of the brain after ppt played video games for 30mons a day for 2 months
• Maguire (2000)


  1) Studied London taxi drivers brains (found more grey matter in posterior hippocampus)

  2) Posterior hippocampus associated with navigational skills

  3)Taxi drivers took "the knowledge test"

  4) This learning alters structure of their brains

  5)The longer they've been in the job, the more noticeable the structural difference is
• Draganski


  1)Imaged medical stu, 3 months before & after their final exams

  2)Found there were changes in posterior hippocampus & parietal cortex

  3) Seen as a result of learning
• Mechelli


  Found larger parietal cortex in brains of bilingual ppl vs monolingual control group
• How does plasticity contribute to the benefits of mindfulness

  Buddhist practices are "an intentional & non-judgemental focus on one's own emotions, thoughts & sensations", which can alter the structure and function of the brain
• Lazar (mindfulness)


  MRI scans showed experienced mediators had thicker cortex, especially in attention & sensory processing areas.
• Holzel (mindfulness)


  Asked ppt to take part in 8 week mindfulness based stress reduction course. Ppt showed high grey matter in left hippocampus (learning & memory area)
• Tang (mindfulness)


  Found 4 weeks of meditation, increased white matter in anterior cingulate cortex
• How does the brain recover functionally after trauma

  Healthy/unaffected areas adapt & compensate for damaged areas by taking over their functions and can occur quickly after trauma. However re cover may slow down & require patient to have rehabitative therapy.
• What is spontaneous recovery?


  When functional recovery occurs quickly after trauma
• How does the neurons allow the brain the recover

  The brain forms new synaptic connections close the the area of damage. Secondary neural pathways that aren't normally activated to enable function to continue
• Name the 4 structural changes happen the brain after trauma

  -Axonal sprouting

  -Reformation of blood vessels

  -Recruitment of homolgois areas

  -Denervation supersensivity
• What is axonal sprouting?

  Growth of new nerve endings, connecting to other undamaged nerve cells to form new pathways
• What is recruitment of homologous(similar) areas

  Opposite side of brain takes on its roles. After some time, the function may switch back to the original side
• What is Denervation supersensivity

  When axons w/ similar jobs become aroused to compensate for the lost ones to reduce severity of impairment.
• Evaluation ...
• Lu et al (disprove)


  Even in healthy indv, neuroplasticity declines with age
• How is practical application a strength

  1) Plasticity research help neuro rehabilitation

  2) Spontaneous recovery slows down eventually, so physical therapy may be necessary to continue improvement

  3)Techniques eg movement therapy & electrical stimulation used to counter motor & cognitive deficits after stroke

  4)This further intervention ensures complete recovery
• Who said support from animal studies is a strength

  Hubel & Wiesel
• Hubel and Wiesel


  Sewed 1 eye of a kitten shut & found the visual area associated with the shut eye wasn't idle but continued to process info from the open eye
• How is age and plasticity a strength

  1) Functional plasticity reduces with age

  2)Brain is used to adapting with new experiences in childhood

  3) BUT Bezzolo found 40 hrs of golf training changed motor cortex of 40-60 yr olds. So neural plasticity continues throughout the lifespan.
• How is negative consequences of plasticity a weakness

  - Prolonged drug use may result in lower cognitive functioning & higher risk of dementia later

  - 60-80% of amputees experience phantom lib syndrome (painful sensation in missing limb), due to cortical reorganisation in somatosensory area
• How is concept of cognitive reserve a weakness

  Edu Attainment may effect how brain recovers from trauma. Schneider found more time brain injury patients had spent in Edu (or cognitive reserve), the higher the chance of Disability Free Recovery. 2/5 DFRs had over 16yr in Edu vs 10% less than 12yr in Edu.