Lesson 9 - Plasticity And Functional Recovery Flashcards
Brain plasticity
Brain plasticity refers to the brain’s ability to change and adapt as a result of experience. Plasticity allows the brain to cope better with the indirect effects of brain damage, such as swelling or haemorrhage following a road accident, or the damage resulting from inadequate blood supply following a stroke.
Effects of Life experience on plasticity
Nerve pathways that are used frequently develop stronger connections, those that are rarely used eventually die. By developing new connections and reducing weak ones the brain is able to adapt to a changing environment. However, there is also a decline in cognitive functioning with age attributed to these changes. Boyke et al. (2008) taught 60 year olds a new skill (juggling), this increased grey matter in the visual cortex.
Effects of video games on plasticity
Kuhn et al. (2014) compared a control group to a group who had been given video game training for at least 30 minutes a day for two months on the game ‘Super Mario’. They found that playing video games caused a significant increase in grey matter in the visual cortex, hippocampus, and cerebellum. Playing video games results in new synaptic connections in brain areas involved in spatial navigation, strategic planning, working memory and
motor performance.
Effects of meditation of plasticity
– Davidson et al. (2004) compared eight practitioners of Tibetan meditation with ten students who had no previous meditation experience. An EEG picked up greater gamma wave activity in the monks, even before they started meditating. Gamma waves coordinate neural activity.
Advantages of Plasticity
+ Kempermann et al. (1998) found far more new neurons in the brains of rats in complex environments compared to those housed in basic cages. This increase in neurons was most prominent in the hippocampus, which is involved in the forming of new long-term memories and the ability to navigate.
+ Maguire et al. (2000) measured grey matter in the brains of London taxi drivers using an MRI scan. The hippocampus in taxi drivers was significantly larger than a control group and this was positively correlated with the amount of time they had spent as a taxi driver (the extent of their life experience).
Functional Recovery
Functional recovery is a form of plasticity. Following damage caused by trauma, the brain can redistribute or transfer functions usually performed by damaged areas to other, undamaged, areas. When the brain is still maturing recovery from trauma is more likely (Elbert et al. 2001), however, the brain is capable of plasticity and functional recovery at any age. Studies have suggested that women recover from a brain injury quicker than men do.
Transfer of functions from damaged areas of the brain to undamaged ones can occur, this is called neural reorganisation. Growth of new neurons and/or connections (axons and dendrites) to compensate for damaged areas can also occur, this is called neural regeneration. Axon sprouting is part of neural regeneration, new nerve endings grow and connect with other undamaged nerve cells to form new neural pathways.
Spontaneous recovery from a brain injury tends to slow down after a number of weeks so physiotherapy may be required to maintain improvements in functioning. Techniques can include movement therapy and electrical stimulation of the brain to counter deficits in motor and cognitive functioning that can be experienced following a stroke.
Advantages of Functional Recovery
+ Phantom Limb Syndrome (PLS) can be used as evidence of neural reorganisation. PLS is the continued experience of sensation in a missing limb, as if it were still there. These sensations are often unpleasant and even painful. PLS is thought to be caused by neural reorganisation in the somatosensory cortex that occurs as a result of limb loss (Ramachandran and Hirstein, 1998).
+ Hubel and Torten Wisel (1963) sewed one eye of a kitten shut and analysed the brain’s cortical response. They found that the visual cortex for the shut eye was not idle (as was predicted) it continued to process information from the open eye. This is further evidence that brain areas can reorganise themselves and adapt their functions.
