Plasticity & Functional Recovery

• what is brain plasticity?

  the brains ability to reorganise neural pathways throughout the lifespan as a result of experiences
• how does the brain change?

  the structure of neurons & an increase in synapses
• as people gain new experiences, the nerve pathways that are frequently used become stronger
• life experiences

  Boyke et al (2008) - found evidence of brain plasticity in 60 year olds juggling
• what did Boyke find?

  an increase in grey matter in visual cortex, when the practice stopped, the changes were reversed
• video games

  Kühn et al (2014) - compared control group with video-trained pps. they trained for 2 months for 30+ mins a day
• what did Kühn find?

  there was a significant increase in grey matter in the cortex, hippocampus, and cerebellum (this was not evident in control group)

  there were new synaptic connections in areas involving spatial navigation, strategic planning etc
• meditation

  Davidson et al. (2004) - compared 8 practitioners of Tibetan monks & 10 student volunteers (no meditation experience).

  they were fitted with electrodes (they pick up gamma waves) during meditation.

  there was more activation of gamma rays in the monks
• what are gamma rays?

  • high-energy & fast acting electromagnetic radiation.
  • passes information rapidly and subtly
  • correlated with large scale brain network & cognitive phenomena (attention etc)
  • can be increased in amplitude via meditation
• AO3: research support from animal studies

  Kempermann et al. - an enriched environment could alter the number of neurons in the brain

  • found an increased number of new neurons in the brains of rats housed in complex environments compared to rats housed in laboratory cages
  • showed the increase of neurons in the hippocampus
• what is the hippocampus associated with?

  the formation of new memories & navigation
• AO3: research support from human studies

  Maguire et al - changes in the brain could be detected as a result of their extensive experience of spatial navigation

  • using an MRI scanner, researchers calculated the amount of grey matter in the brains of taxi drivers and control pps
  • the posterior hippocampi was significantly larger in taxi drivers
  • posterior hippocampal volume was positively correlated with the amount of time spent as a taxi driver

  highest level of plasticity were evident in those with more extensive experience
• what is functional recovery?

  The process of regaining abilities or skills that were lost or impaired due to injury or illness.
• what are the two ways in which the brain is able to regenerate?

  neuronal unmasking and stem cells
• what is neuronal unmasking?

  Wall - when dormant synapses (that exist anatomically & are blocked) become active when the surrounding brain area becomes damaged and creates a lateral spread of activation which gives way to the development of new structures
• what are stem cells?

  Undifferentiated cells that have the potential to develop into various types of specialized cells in the body.
• how do stem cells aid the recovery of the brain?

  • replacing the dead cells
  • secreting growth factors to help repair damaged cells
  • form new neural networks that links the uninjured part of the brain to the injured part.
• AO3: research support from animal studies

  Tajiri et al. - evidence for the role of stem cells in recovery from brain injury

  • randomly assigned brain injured rats into two groups
  • one group received a solution with stem cells and the other received solution with nothing in it
  • 3 months later, it was seen that brains of stem cell rats showed clear developments of neuron-like cells in the area of injury
  • it was also accompanied by a solid stream of stem cells migrating to the brains site of injury
• AO3: age differences in functional recovery

  Huttenlocher - functional plasticity reduces with age

  • studies have suggested that abilities commonly thought to be fixed in childhood can be fixed in adulthood but with intense training

  Elbert et al. - neural reorganisation is much greater in children than in adults
• AO3: educational attainment

  Schneider et al. - patients with college education are 7x more likely than those who did not finish highschool to recover from a traumatic brain injury

  • US Traumatic Brain Injury Systems database
  • 214/769 patients had disability free recovery
  • 39.2% 16+ years of education, 30.8% 12-15, 9.7% less than 12 years

  cognitive reserve was an important factor in neural adaptation