Plasticity & functional recovery of the brain after trauma

What is plasticity

The brains tendency to change and adapt as a result of experience and new learning. This involves the growth of new connections

What happens to the brain during infancy

It experiences a rapid growth in the number of synaptic connections, peaking at about 15,000 per neuron at 2-3 years of age. This is about twice as many as there are in the adult brain

What happens to connections in the brain as we age and what is the process known as

Rarely used connections are deleted and frequently used connections are strengthened - synaptic pruning

What did Eleanor Maguire et al. study

The brains of London taxi drivers

What did she find

Significantly more volume of grey matter in the posterior hippocampus than in a matched control group

What is the posterior hippocampus associated with

The development of spatial and navigational skills in humans and other animals

What do London cab drivers have to do as part of their training and what did Maguire find about this

They have to complete a knowledge test that assesses their recall of the city streets and possible routes. She found that this experience alters the structure of taxi drivers brains. She also found that the longer they had been on the job, the more pronounced the structural difference was

Who found a similar finding and in what study

Bogdan Draganski et al. - imaged brains of medical students three months before and after final exams. Learning induced changes were seen to have occurred in the posterior hippocampus and parietal cortex

What is functional recovery and what is it an example of

The brains ability to redistribute or transfer functions usually performed by the damaged area to a non damaged area - example of plasticity

What happens in the brain during recovery

It is able to rewire and reorganise itself by forming new synaptic connections close to the area of damage

What is activated or ‘unmasked’ to enable functions to continue

Secondary neural pathways

What is the first thing that supports this unmasking process

Axonal sprouting: the growth of new nerve endings which connect with other undamaged nerve cells to form new neuronal pathways

What is the second thing that supports this unmasking process

Denervation supersensitivity: this occurs when axons that do a similar job become aroused to a higher level to compensate for those that have been lost. However, it can have a negative consequence of oversensitivity to messages such as pain

What is the third thing that supports this unmasking process

Recruitment of homologous areas on the opposite side of the brain: This means that specific tasks can still be performed. An example would be if Broca’s area was damaged on the left side of the brain, the right-sided equivalent would carry out its functions. After a period of time, functionality may then shift back to the left side

What is a limitation of plasticity

It may have negative behavioural consequences. Evidence has shown that the brains adaption to prolonged drug use leads to poorer cognitive functioning in later life, as well as increased risk of dementia (Medina et al. (2007). Also, 60-80% of amputees have been known to develop phantom limb syndrome, which is unpleasant and painful. It is thought to be due to cortical reorganisation in the somatosensory cortex that occurs as a result of limb loss (Ramachandran and Hirstein 1998). This suggests that the brains ability to adapt to damage is not always beneficial

What is a strength of plasticity

Brain plasticity may have a life-long ability. In general plasticity reduces with age, however Ladina Bezzola et al. (2012) demonstrated how 40 hours of golf training produced changes in the neural representations of movements in participants aged 40-60. Using fMRI researchers observed increased motor cortex activity in the novice golfers compared to a control group, suggesting more efficient neural representations after training. This shows that plasticity can continue throughout the lifespan

What is a strength of functional recovery

Its real-world application. Understanding the processes of plasticity has contributed to neurorehabilitation. Understanding axonal growth is possible encourages new therapies to be tried. For example, constraint-induced movement therapy is used with stroke patients where they repeatedly practice using the affected part of their body whilst the unaffected is restrained. Shows research into functional recovery is useful as it helps medical professionals know when intervention needs to be made

What is a limitation of functional recovery

The level of education may influence recovery rates. Eric Schneider et al. (2014) revealed that the more time people with brain injury had spent in education, the greater their changes of a disability-free recovery (DFR). 40% of those who achieved DFR had more than 16 years in education compared to about 10% of those who had less than 12 years of education. This implies that people with brain damage that have insufficient DFR are less likely to achieve a full recovery