Specification: Plasticity and functional recovery of the brain after trauma.
Plasticity
The brain is not a static organ, and the functions and processes of the brain can change as a result of experience and injury. Brain plasticity refers to the brain’s ability to change and adapt because of experience. Research has demonstrated that the brain continues to create new neural pathways and alter existing ones in response to changing experiences.
Functional recovery
The brain also appears to show evidence of functional recovery: the transfer of functions from a damaged area of the brain after trauma to other undamaged areas. It can do this through a process termed neuronal unmasking where ‘dormant’ synapses (which have not received enough input to be active) open connections to compensate for a nearby damaged area of the brain. This allows new connections in the brain to be activated, thus recovering any damage occurring in specific regions.
Evaluation of plasticity and functional recovery
Kuhn et al. found a significant increase in grey matter in various regions of the brain after participants played video games for 30 minutes a day over a two-month period. Similarly, Davidson et al. demonstrated the permanent change in the brain generated by prolonged meditation: Buddhist monks who meditated frequently had a much greater activation of gamma waves (which coordinate neural activity) than did students with no experience of meditation. These two studies highlight the idea of plasticity and the brain’s ability to adapt as a result of new experience, whether it’s video games or mediation.
There is further research to support the notion of brain plasticity. Maguire et al. found that the posterior hippocampal volume of London taxi drivers’ brains was positively correlated with their time as a taxi driver and that there were significant differences between the taxi drivers’ brains and those of controls. This shows that the brain can permanently change in response to frequent exposure to a particular task. However, some psychologists suggest that research investigating the plasticity of the brain is limited. For example, Maguire’s research is biologically reductionist and only examines a single biological factor (the size of the hippocampus) in relation to spatial memory. This approach is limited and fails to take into account all of the different biological/cognitive processes involved in spatial navigation which may limit our understanding. Other psychologists suggest that a holistic approach to understanding complex human behaviour may be more appropriate.
There is research to support the claim for functional recovery. Taijiri et al. (2013) found that stem cells provided to rats after brain trauma showed a clear development of neuron-like cells in the area of injury. This demonstrates the ability of the brain to create new connections using neurons manufactured by stem cells.
While there is evidence for functional recovery, it is possible that this ability can deteriorate with age. Elbert et al. concluded that the capacity for neural reorganisation is much greater in children than in adults, meaning that neural regeneration is less effective in older brains. This may explain why adults find change more demanding than do young people. Therefore, we must consider individual differences when assessing the likelihood of functional recovery in the brain after trauma.
A final strength of research examining plasticity and functional recovery is the application of the findings to the field of neurorehabilitation. Understanding the processes of plasticity and functional recovery led to the development of neurorehabilitation which uses motor therapy and electrical stimulation of the brain to counter the negative effects and deficits in motor and cognitive functions following accidents, injuries and/or strokes. This demonstrates the positive application of research in this area to help improve the cognitive functions of people suffering from injuries.
Possible exam questions
Explain what is meant by the term ‘plasticity’. (2 marks)
Outline evidence in relation to brain plasticity. (4 marks)
Outline evidence in relation to functional recovery. (4 marks)
David is fourteen years old. Last year, he was hit by a bus when walking to school and suffered from serious head injuries. While David made a full physical recovery, he has problems with his speech and comprehension of language. However, after one year, David had recovered nearly all of his language abilities. Use your knowledge of functional recovery and plasticity to explain David’s recovery. (4 marks)
Discuss evidence for plasticity and/or functional recovery after trauma. (16 marks)
