Plasticity and functional recovery

1. Plasticity and functional recovery

2. Starter: • Today we’re looking at ‘plasticity’ of the brain……. • Concentrate on the word ‘plasticity’; • What qualities doe you think this word is conveying about the brain? • If the word ‘plasticity’ didn’t exist which words do you think psychologists could use to replace it.

3. It may be possible in the exam that you are asked a 16 marker about either plasticity or functional recovery. If the wording is ‘plasticity’ it may be possible to include information on functional recovery as long as you explain if you recover you are showing plasticity. If the question only mentions functional recovery you need to be careful that you only talk about those who are recovering and ignore the plasticity associated with normal growth.

4. Plasticity of the brain (Also known as Neuroplasticity or cortical remapping ). This describes the brains tendency to change and adapt (functionally and physically) as a result of experience and new learning. https://www.youtube.com/watch?v=ELpfYCZa87g During infancy, the brain experience a rapid growth in the number of synaptic connections it has, peaking at approximately 15,000 by the age of 2-3 years old. This equates to twice as many as there are in the adult brain. As we age rarely used connections are deleted and frequently used connections are strengthened in a process known as cognitive pruning. This shows that the brain is in a continual state of change from growth in early years to change and refinement in adulthood as we learn and experience.

5. Sharp Brains Plasticity research: How Learning changes our brains ElanorMaguire et al (2000) studied the brains of London taxi drivers using an MRI and found significantly more grey matter in the posterior hippocampus than in the 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 is also noteworthy that the longer they had been doing the job the more pronounced was the structural difference (a positive correlation). APRC for this study

6. Evaluation of Mcguire et al • Control group allows us to say that there is a significant difference between taxi drivers and others. (good design). • Use of scientific, objective measurements (MRI) • An attempt to study a real world phenomena. • We can’t be sure that the difference is due to the ‘knowledge’. They could have been taxi drivers because of their already existing difference. (although the positive correlation between experience and structure makes this less likely) • Androcentric – lacks population validity

7. Functional recovery Following physical injury or other forms of trauma such as infection or the experience of a stroke, unaffected areas are sometimes able to adapt or compensate for those areas that are damaged. The functional recovery that occurs in these cases is an example of neural plasticity. Neuro scientists suggest that this can happen quickly after trauma (spontaneous recovery) and then slow down after several weeks or months. Therapy may then be needed. https://www.youtube.com/watch?v=VaDlLD97CLM

8. What happens in the brain during recovery? The brain is able to rewire and reorganise it’s self by forming new synaptic connections close to the area of damage. Secondary neural pathways that would not typically be used to carry out certain functions are ‘unmasked’ to enable functioning to continue. This process is supported by a number of structural changes. 1.Axon sprouting: new nerve endings grow and connect with undamaged areas. 2. Reformation of blood vessels. 3. Recruitment of homologous (similar)areas on the opposite hemisphere to do specific tasks

9. Research into functional recovery Tajiri et al (2013) provided evidence for the role of stem cells in recovery from brain injury. They randomly assigned rats with traumatic brain injury to one of 2 groups. One group received transplants of stem cells into the region of the brain affected by traumatic injury. The control group received a solution infused into the brain containing no stem cells. Three months after the brain injury, the brains of stem cell rats showed clear development of neuron-like cells in the area of injury. This was accompanied by a solid stream of stem cells migrating to the brain’s site of injury. This was not the case with the control group. APRC for this study • Animal study so hard to generalise to humans • Animal studies enable us to monitor the function of the brain before and after trauma because we cause it. Ethically we couldn’t do this in humans and it’s unlikely that we would have measured their function before a natural event (because we didn’t know it was going to happen).

10. Factors affecting recovery of the brain after trauma: Read and make notes on the following: Perseverance Physical exhaustion, stress and alcohol consumption Age Gender

11. Possible Exam Questions: Describe and evaluate evidence of plasticity and functional recovery after trauma in the brain. (16 marks) Joseph suffered a stroke when he was 45-years-old. He could move his left arm and leg but was paralysed down his right side. While Joseph could understand what was said to him, he was unable to speak. Referring to Joseph, discuss hemispheric lateralisation of language centres in the brain. (16 marks).

12. Prep – Explore these websites and videos https://www.headway.org.uk/