plasticity + functional recovery of the brain

• plasticity: in recent years it has become clear not only that neuronal organisation is changes as a result of experience, but also that there are many different types of experience that can do this
• plasticity: factors that are now known to affect neuronal structure and function include life experience, video games and even meditation
• plasticity as a result of life experience: as people gain new experiences, nerve pathways that are used frequently develop stronger connections whereas neurons that are rarely or never used eventually die
• plasticity as a result of life experience: by developing new connections and pruning away weak ones the brain is able to constantly adapt to a changing environment
• plasticity as a result of life experience: however there is also a natural decline in cognitive functioning w/ age that can be attributed to changes in the brain, this has led to researchers to look for ways in which new connections can be made to reverse this effect
• plasticity as a result of life experience: e.g. Boyke et al (2008) found evidence of brain plasticity in 60 year olds taught a new skill - juggling, they found increases in grey matter in the visual cortex, although when practicing stopped these changes were reversed
• playing video games: playing video games makes many different complex cognitive and motor demands, Kuhn et al (2014) compared a control group w/ a video game training group that was trained for 2 months for at least 30 minutes per day on the game Super Mario
• playing video games: they found a significant increase in grey matter in various brain areas including the cortex, hippocampus and cerebellum, this increase was no evident in the control group that did not play Super Mario
• playing video games: the researchers concluded that video game training had results in new synaptic connections in brain areas involved in spatial navigation, strategic planning, working memory and motor performance - skills that were important in playing the game successfully
• meditation: researchers working w/ Tibetan monks have been able to demonstrate that meditation can change the inner workings of the brain
• meditation: Davidson et al (2004) compared 8 practitioners of Tibetan meditation w/ 10 student volunteers w/ no previous meditation experience, both groups were fitted w/ electrical sensors and asked to meditate for short periods
• meditation: the electrodes picked up much greater activation of gamma waves (Important because they coordinate neuron activity) in the monks, the students showed only a slight increase in gamma wave activity while meditating
• meditation: the researchers concluded that meditating not only changed the working of the brain in the short term, but may also produce permanent changes based on the fact that the monks had far more gamma wave activity than the control group even before they started meditating
• functional recovery after trauma: in the 1960s researchers studied case studies in which stroke victims were able to regain functioning, they discovered that when brain cells are damages or destroyed as they are during a stroke the brain re-wires itself over time so that some level of function can be regained
• functional recovery after trauma: although parts of the brain may be damaged or even destroyed as a result of trauma, other parts appear able to take over the functions that were lost, neurons next to damaged areas can form new circuits that resume some of the lost function
• mechanisms for recovery: regenerative developments in brain functions arise from the brains plasticity, its ability to change structurally and functionally following trauma, 2 ways in which the brain is able to do this are neuronal unmasking and stem cells
• neuronal unmasking: Wall (1977) 1st identified what he called 'dormant synapses' in the brain, these are synaptic connections that exist anatomically but their function is blocked
• neuronal unmasking: under normal conditions these synapses may be ineffective because the rate of neural input to them is too low for them to be activated, however increasing the rate of input to these synapses as would happen when a surrounding brain area becomes damaged can then open (or 'unmask') these dormant synapses
• neuronal unmasking: the unmasking of dormant synapses can open connections to regions of the brain that are not normally activated creating a lateral spread of activation which in time gives way to the development of new structures
• stem cells: stem cells are unspecialised cells that have the potential to give rise to different cell types that carry out different functions including taking on the characteristics of nerve cells
• stem cells: there are a number of views on how stem cells might work to provide treatments for brain damage caused by injury or neurodegenerative disorders, the 1st view is that the stem cells implanted into the brain would directly replace dead or dying cells
• stem cells: a seconds possibility is that transplanted stem cells secrete growth factors that somehow 'rescue' the injured cell, a third possibility is that transplanted cells form a neural network which links an uninjured brain site where new stem cells are made w/ the damaged region of the brain
• evaluation plasticity S: Maguire et al (2000) in a study of London taxi drivers discovered that changes in the brain could be detected as a result of their extensive experience of spatial navigation, this not only shows that hippocampal volume was greater in those people w/ job-related experience of spatial navigation but also that the highest levels of plasticity were evident in those w/ more extensive experience
• evaluation plasticity S: Kempermann et al (1998) suggested that an enriched environment could alter the number of neurons in the brain - they found evidence of an increased number of new neurons in the brains of rats housed in a complex environment compared to those in laboratory cages, clear evidence of the brain's ability to change as a result of experience i.e. it demonstrates plasticity
• evaluation functional recovery S: Tajiri et al (2013) provided evidence for the role of stem cells in recovery from brain injury, in the study there were no developments of new neuronal cells in the control group which then supports the important role played by stem cells in recovery from brain injury
• evaluation functional recovery S: it is commonly accepted view that functional plasticity reduces w/ age (Huttenlocher, 2002) studied have suggested that even abilities commonly thought to be fixed in childhood can still be modified in adults w/ intense restraining, Elbert et al concluded that the capacity for neural reorganisation is much greater in children than in adults, as demonstrated by the extended practice that adults require in order to produce changes
• evaluation functional recovery S: Schneider et al (2014) found that patients w/ the equivalent of a college education are 7x more likely than those who didn't finish high school to be disability-free 1 year after a moderate to severe traumatic brain injury, researchers concluded that 'cognitive reserve' was an important factor in neural adaptation during recovery from traumatic brain injury
• evaluation functional recovery L: case studies frequently show functional recovery but have limited generalisability and although high in mundane realism, lack the necessary control to scientifically validate the process