Plasticity and Functional recovery of the brain

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  • Plasticity and functional recovery of the brain
    • Plasticity
      • Plasticity as a result of life experience
        • Boyke 2008 found an increase in grey matter in 60 year olds after being taught how to juggle however when they stopped practising the changes were reversed
        • When you gain a new experience frequently used nerve pathways are  develop stronger connections and the ones that are rarely used die
          • This way your Brain is able to adapt to a changing environment
          • There is a natural decline with age in cognitive functioning
      • Playing video games
        • In a study by Kühn compared a control group with a group that had played super Mario for 2 months for at least 30 minutes a day
          • They found a significant increase in grey matter in various brain areas including the cortex, hypothalamus and cerebellum.
            • This was not found in the control group
          • They concluded that playing the video game had resulted in new synaptic connection in brain areas involved in spacial navigation
      • Meditation
        • Meditation can cause permanent change to the working of the brain
          • The monks showed high levels of gamma waves before they started meditating.
        • Study where Tibetan monks were compared to 10 students with no previous meditation experience
          • Both groups were fitted with electrical sensors that picked up gamma waves on the monks and very slight increase in gamma wave activity in the student while meditating
    • Functional recovery after trauma
      • Mechanisms for recovery
        • Neuronal unmasking:
          • Dormant synapses are synaptic connections that exist anatomically however their function is blocked
            • Ineffective under normal conditions due to a low rate of neural input so they cannot be activated
          • Increasing the rate of input into the synapses can open (unmask) this then opens connections to regions pf the brain that are not normally activated creating a lateral spread of activation which leas to the development of new structure
        • Stem cells:
          • Unspecialised cells that can rise to different cell types that carry out different functions including nerve cells
          • 1. stem cells implant into the brain would directly replace dead or dying cells
          • 2. transplanted stem cells secrete growth factors that rescue the injured cells
          • 3. transplanted cells form a neutral network which links an uninjured brain site where new stem cells are made with a damaged region of the brain
    • Evaluation:
      • Evaluation of Plasticity
        • Research support from animal studies:
          • Kempermann investigated whether an enriched environment could alter the number of new neurons in the brains of rats
            • They found an increased number of new neurons (particularly in the hippocampus)  in the brains of the rats in the complex environment compared to those in lab cages
        • Research support from human studies:
          • Maguire studied London taxi drivers to discover whether changes in the brain could be detected as a result of extensive spatial navigation
            • Using MRI the researcher calculated the amount of grey matter in the brains of the drivers and a set of control PP's
              • Posterior hippocampi in the taxi drivers was significantly larger relative to the control PP's an posterior hippocampal volume was positively correlated with the amount of time spent as a taxi driver
      • Evaluation of functional recovery after trauma
        • Research support from animal studies:
          • Tajiri provided evidence for the role of stem cells in recovery from brain injury
            • Randomly allocated rats with traumatic brain injury to one of 2 groups
              • Group 1 received transplant stem cells into the region of the brain affect
                • The control group received a solution infused with into the brain contains no stem cells
              • After 3 months the brains of the stem cell rats showed clear development of neuron like cells also a solid stream of stem cells migrating the the injured site of the brain
                • Not found in the control group
        • Age difference in functional recovery:
          • Functional plasticity reduces with age so after childhood the only option following brain trauma beyond childhood is to develop compensatory behavioural strategies to work around the deficit
            • Studies have suggested even abilities commonly though to be fixed in childhood can still be modified in adults with intense retraining
              • The capacity for neural reorganisation is greater in children than in adults this has been demonstrated by the extended practice that adults require in order to produce changes
        • Educational attainment and functional recovery:
          • Schneider found patients with the equivalent to a college education are 7 times more likely than those who didn't complete high school to be disability free a year after traumatic brain injury
            • A retrospective study based on data from the US Traumatic Brain Injury System Database of 769 PP's 214 had achieved disability free recovery after  a year
              • 39.2% of these PP's with 16 or more years of education achieved DFR as had 30.8% with 12-15 years and just 9.7% of those with less than 12 years
                • Researcher concluded that cognitive reserve could be a factor in neural adaption during recovery from traumatic brain injury


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