AQA Psychology for A Level Year 2 - Student Bk

The specification says… plasticity and functional recovery of the brain after trauma Plasticity and functional recovery of the brain after trauma. Neural plasticity is the apparent ability of the brain to change and adapt its structures and processes as a result of experience and new learning. This links directly to the notion of functional recovery – the way that certain abilities of the brain may be moved or redistributed rather than lost following damage or trauma to the brain. Key terms Plasticity – (also referred to as neuroplasticity or cortical remapping) This describes the brain’s tendency to change and adapt (functionally and physically) as a result of experience and new learning. Functional recovery – A form of plasticity. Following damage through trauma, the brain’s ability to redistribute or transfer functions usually performed by a damaged area(s) to other, undamaged area(s). Methods: Brainy cab drivers A researcher compared the hippocampal volume of taxi drivers (who drive different routes every day) with bus drivers (who follow the same routes every day). The researcher used an unrelated t -test to analyse the data and a significant difference was found at the 0.05 level. Questions 1. Explain two reasons why the unrelated t -test was an appropriate choice for this investigation. (4 marks) (See page 70) 2. With reference to this investigation, explain what is meant by the phrase ‘a significant difference was found at the 0.05 level’. (2 marks) (See page 72) @ookx hs @ookx hs Plasticity and functional recovery of the brain after trauma Brain plasticity The brain would appear to be ‘plastic’ (not literally – it’s a metaphor!) in the sense that it has the ability to change throughout life. During infancy, the brain experiences a rapid growth in the number of synaptic connections it has, peaking at approximately 15,000 at age 2–3 years (Gopnick et al . 1999). This equates to about twice as many as there are in the adult brain. As we age, rarely used connections are deleted and frequently used connections are strengthened – a process known as synaptic pruning . It was originally thought that such changes were restricted to the developing brain within childhood, and that the adult brain, having moved beyond a critical period, would remain fixed and static in terms of function and structure. However, more recent research suggests that at any time in life existing neural connections can change, or new neural connections can be formed, as a result of learning and experience ( plasticity ). Research into plasticity Eleanor Maguire et al . (2000) studied the brains of London taxi drivers and found significantly more volume of grey matter in the posterior hippocampus than in a matched control group. This part of the brain is associated with the development of spatial and navigational skills in humans and other animals. As part of their training, London cabbies must take a complex test called ‘The Knowledge’, which assesses their recall of the city streets and possible routes. It appears that the result of this learning experience is to alter the structure of the taxi drivers’ brains. It is also noteworthy that the longer they had been in the job, the more pronounced was the structural difference (a positive correlation ). A similar finding was observed by Draganski et al . (2006) who imaged the brains of medical students three months before and after their final exams. Learning-induced changes were seen to have occurred in the posterior hippocampus and the parietal cortex presumably as a result of the exam. Finally, Mechelli et al. (2004) also found a larger parietal cortex in the brains of people who were bilingual compared to matched monolingual controls. Functional recovery of the brain after trauma Following physical injury, or other forms of trauma such as the experience of a stroke, unaffected areas of the brain are often able to adapt and compensate for those areas that are damaged. The functional recovery that may occur in the brain after trauma is another example of neural plasticity. Healthy brain areas may take over the functions of those areas that are damaged, destroyed or even missing. Neuroscientists suggest that this process can occur quickly after trauma (spontaneous recovery) and then slow down after several weeks or months. At this point the individual may require rehabilitative therapy to further their recovery (see facing page). What happens in the brain during recovery? The brain is able to rewire and reorganise itself by forming new synaptic connections close to the area of damage (a bit like avoiding roadworks on the way to school by finding a different route). Secondary neural pathways that would not typically be used to carry out certain functions are activated or ‘unmasked’ to enable functioning to continue, often in the same way as before (Doidge 2007). This process is supported by a number of structural changes in the brain including: • Axonal sprouting : The growth of new nerve endings which connect with other undamaged nerve cells to form new neuronal pathways. • Reformation of blood vessels. • Recruitment of homologous (similar) areas on the opposite side of the brain to perform specific tasks. 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. Functional recovery after trauma is one dramatic example of how the brain is plastic and has the ability to adapt to changing circumstances. For this reason, if you are discussing brain plasticity, it would be acceptable to use material on ‘functional recovery after trauma’ within the answer. Study tip ’You wouldn’t believe the size of my mid-posterior hippocampus, mate.’ A London cabbie talks brain plasticity. Chapter 2 Biopsychology 40 •