plasticity and functional recovery Flashcards
plasticity as a result of life experience
as people gain new experiences, nerve pathways used frequently develop stronger connections, whereas neurons rarely or never used eventually die
by developing new connections and pruning away weak ones, the brain constantly adapts to a changing environment. however, there’s also natural decline in cognitive functioning with age that can be attributed to changes in brain
plasticity - playing video games
playing video games makes complex cognitive and motor demands
kuhn et al - compared control group with video game training group that was trained for 2 months at least 30 mins per day - found significant increase in grey matter in various brain areas of video game training group, including cortex, hippocampus and cerebellum
concluded video game training resulted in new synaptic connections in brain areas involved in spatial navigation, strategic planning, working memory and motor performance
plasticity - meditation
davidson et al - compared 8 practitioners of tibetan meditation with 10 student volunteers with no previous meditation experience. both groups were fitted with electrical sensors and asked to mediate for short periods - electrodes picked up greater activation of gamma waves in monks while student showed only slight increase in gamma wave activity
concluded meditation may produce permanent changes in brain based on fact that monks had more gamma wave activity than control group even before they started meditating
functional recovery - mechanisms for recovery - neuronal unmasking
wall - identified dormant synapses - synaptic connection that exist anatomically but their function is blocked. increasing rate of input to these synapses can unmask the dormant synapses which can open connections to regions of the brain that aren’t normally activated, allowing development of new structures
functional recovery - stem cells
how stem cells might provide treatments for brain damage caused by injury:
stem cells directly implanted into brain replace dead or dying cells
transplanted stem cells secrete growth factors that somehow ‘rescue’ injured cells
transplanted cells form neural network which links uninjured brain site where new stem cells are made with damaged region of brain
plasticity evaluation - research support from human studies
maguire et al - studied london taxi drivers and discovered changes in brain could be detected as result of extensive experience in spatial navigation
using MRI scanner, they calculated amount of grey matter in brains of taxi drivers and control group. posterior hippocampi of taxi drivers were significantly larger relative to control group and posterior hippocampal volume was positively correlated with amount of time they spent as taxi driver
shows highest level of plasticity was evident in those with more extensive experience
plasticity evaluation - research support from animal studies
kempermann et al - suggested enriched environment could alter number of neurons in brain.
found evidence of increased number of neurons in brains of rats housed in complex environments compared to rats housed in lab cages. rats housed in complex environment showed increase in neurons in hippocampus which is associated with formation of new memories and ability to navigate from one location to another
shows clear evidence of brain’s ability to change as a result of experience
functional recovery evaluation - research support from animal studies
tajiri et al - provided evidence for role of stem cells in recovery from brain injury
randomly assigned rats with traumatic brain injury to one of 2 groups. one group received transplants of stem cells into regions of brain affected by injury, control group received solution infused into brain containing no stem cells
3 months later brains of stem cell rats showed clear development of neuron-like cells in area of injury accompanied by stem cells migrating to brain’s site of injury - supports importance of stem cells in recovery from brain injury
functional recovery evaluation - age differences in function recovery
commonly accepted view that functional plasticity reduces with age - only option following brain injury beyond childhood is to develop compensatory behavioural strategies to work around the deficit.
however, studies suggest that even abilities commonly thought to be fixed in childhood can still be modified in adults with intense retraining
however, elbert et al conlucded capacity for neural reorganisation is much greater in children than adults, as demonstrated by extended practice adults require to produce changes
