Plasticity and function recovery of the brain Flashcards
(14 cards)
What does brain plasticity mean?
refers to the brains ability to modify its own structure and function as a result of experience
How is plasticity a result of life experience?
As people gain new experiences, nerve pathways that are used frequently develop stronger connections, whereas neurons that are rarely used will eventually die out - allows brain to adapt to changing environment
How does age affect plasticity? What has this led researchers to do?
There is a natural decline in cognitive functioning with age that can be attributed to changes in the brain
Researchers look for ways in which connections can be made to reverse this effect a.g. Boyke et al - found evidence of brain plasticity in 60 year olds taught a new skill (juggling) - found increases in grey matter in the visual cortex, although when practising stopped these changes were reversed
How do video games increase neural activity? What study supports this?
Playing different video games makes many different cognitive and motor demands
Kühn et al - those who played Mario cart for 30 mins per day for 2 months had significant increase in grey matter in various areas of the brain (cortex, hippocampus and cerebellum) - control group did not have this
Researchers concluded that video games result in new synaptic connections in brain areas involved in spatial navigation, strategic planning, working memory and motor performance (skills important in playing the game successfully)
How has meditation been shown to affect the inner workings of the brain?
Davidson et al - compared 8 practitioners of Tibetan meditation with 10 student volunteers with no previous meditation experience - both fitted with electrical sensors and asked to meditate for short periods of time
Monks = greater activation of gamma waves (important as they coordinate neuron activity)
Students = only a slight increase
Researchers concluded meditation not only changes the workings go the brain in the short term but also produce permanent changes (monks had more gamma ways even before they started meditating)
What research support is there for plasticity?
Maguire et al - London taxi drivers
- MRI scanner found the researcher calculated the amount of grey matter of taxi drivers and a set of control participants
- Posterior hippocampi of taxi drivers was significantly larger relative to those of the control participants (job requires increased spatial navigation)
- Posterior hippocampal volume was positively associated with the amount of time they had spent as a taxi driver
- Plasticity also more extensive in those with more extensive experiences
What research support is there from animals?
Kempermann et al - an enriched environment could alter number of neurons in the brain
- Found an increase in neuorns in rats housed in complex environments compared to rats housed in laboratory cages (particularly an increase in neurons in the hippocampus- part of the brain associated with formation of new memories and ability to navigate)
CANNOT generalise animal studies to humans e.g. humans have conscious, much more complex…
What did researchers in the 1960s study? and what did they find?
Cases where stroke victims were able to regain functioning
They discovered the brain rewires itself over time so that some level of function can be regained - although some parts of brain are damaged of even destroyed by trauma - other parts appear to take over the functions
What can happen to neurons that to damaged areas of the brain?
They form new circuits that resume some of the lost function
What are the two ways in which the brain is able to change structurally and functionally following trauma?
Neural unmasking
Stem cells
What is neuronal unmasking as a way of functional recovery and who suggested it?
Wall - first identified ‘dormant synapses’ which are synaptic connections that exist anatomically but their function is blocked (usually ineffective because the rate of neural input to them is too low). However, increasing the rate of input (e.g. through brain damage) can unmask these synapses - creating a literal spread of activation which in time gives development of new structures
How do stem cells help with functional recovery?
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
Three possibilities on how stem cells might work to provide treatment:
1) stem sells implanted into the brain directly replace dead or dying cells
2) stem cells secrete growth factors that somehow ‘rescue’ the injured cells
3) transplanted cells from a neural network, which links an uninjured brain site, where now stem cells are made, with the damage region of the brain
What research support is there from animal studies for functional recovery?
Tajiri et al - randomly assigned rats with traumatic brain injury to one of two groups = one received transplants of stem cells into the brain affected by traumatic injury
- control group received a solution infused into the brain with no stem cells
3 months later, rats showed clear development of neutron-like cells in the area of injury (accompanied by a solid stream of stem cells migrating to the brains site of injury) - not evident in control group
How has educational attainment been shown to help functional recovery?
Schneider et al - patients with the equivalent of a college education are 7 times more likely than those who didn’t finish school to be disability-free one year after a moderate-severe traumatic brain injury
Carried out a retrospective study based on data from US Traumatic Brain Injury Systems Database - of the 769 studies 214 had achieved disability-free recovery (DFR) after 1 year
- Of these, 39.2% had 16+ years of education compared to 30.8% of those with 12-15 years of education, (9.7% = those with less than 12 years)
Researchers concluded that ‘cognitive reserve’ (associated with greater educational attainment) was an important factor in neural adaption during recovery from traumatic brain injury
