Plasticity & Functional Recovery of the Brain After Trauma (AQA A Level Psychology): Revision Note

Plasticity & functional recovery of the brain after trauma

• Neuroplasticity refers to the brain's ability to adapt and change in response to experience, learning, or damage

• The brain is not a static, concrete mass

  • It is a flexible organ that responds and adapts to environmental stimuli and stressors

• There are two key processes to understand:

  • plasticity - changes in the brain's structure and connections due to learning and experience

  • functional recovery - the brain's ability to reorganise itself and recover lost functions after trauma or injury

Plasticity

• Plasticity refers to changes within brain structures and connections in response to learning, experience, or repeated activity

  • These changes happen gradually and reflect the degree of learning or experience

• The build-up of grey matter in particular brain regions is due to increased synaptic connections in those areas

• Plasticity also involves neural (synaptic) pruning, where frequently used synapses are strengthened and unused ones are cleared away, making the network more efficient

Examples of neuroplasticity

• London black cab taxi drivers spend years learning routes through central London

  • Their brains show increased grey matter in the posterior hippocampus, a region linked to spatial navigation (Maguire et al. 2000)

• People who learn a juggling routine show increased grey matter in the mid-temporal cortex compared to non-jugglers

  • When the jugglers stopped practising for three months, the grey matter linked to juggling decreased (Draganski et al. 2004)

  • This shows both plasticity (growth) and neural pruning (loss of unused connections)

• People who practice mindfulness show increased grey matter in the prefrontal cortex and decreased grey matter in the amygdala

  • Participants in this study reported a decrease in stress and anxiety symptoms (Gotink et al. 2016)

Functional recovery after trauma

• Functional recovery refers to the brain's ability to recover lost functions after trauma or injury

  • It does this by reorganising itself and using healthy regions to take over the work of damaged ones

• Functions such as mobility, memory and language can be partially or fully recovered, although the recovery is not always 100% of the original ability

• Functional recovery tends to begin with a rapid growth spurt, then slow down and eventually plateau

• Recovery is generally faster and more complete in younger brains, as ageing brains have reduced synaptic activity

Mechanisms of functional recovery

• Axonal sprouting - new nerve endings grow from surviving neurons and link up with undamaged cells, forming alternative neural circuits

• Reformation of blood vessels (angiogenesis) - damaged tissue triggers the growth of new blood vessels, restoring oxygen and nutrients to the recovering area

• Recruitment of homologous areas - the equivalent region in the opposite hemisphere takes over the function of the damaged area

  • E.g. if Broca's area in the left hemisphere is damaged, its right-hemisphere counterpart may compensate over time

• Neural reorganisation - surviving regions adapt their function and form new connections to support the lost ability

Examples of functional recovery

• A child who had half of her brain removed (hemispherectomy) to control her epilepsy was able to function almost completely normally after surgery

  • This was because her remaining hemisphere took over the tasks of the removed hemisphere

• Danelli et al. (2013) conducted a case study of E.B., a 14-year-old boy who had undergone a left hemispherectomy at age 2 to remove a tumour

  • The surgery removed his language centres, including Broca's and Wernicke's areas

  • Immediately after surgery, E.B. lost all language function

  • Two years later, E.B. had recovered his language ability

  • fMRI scans showed that the right hemisphere was carrying out language functions normally performed by the left

  • This demonstrates functional recovery and the brain's ability to adapt after trauma

Evaluation of plasticity & functional recovery

Strengths

• There is a strong body of research into neuroplasticity supporting the idea that the brain adapts to change

  • When several different studies come to the same conclusion then the theory has good internal validity

  • This means that researchers can rule out alternative explanations

• There are significant practical applications for both plasticity and functional recovery

  • Understanding the brain's capacity to compensate for loss and the slowing-down phase of functional recovery, is key to informing physical and cognitive rehabilitation for patients with brain damage

Limitations

• Neuroplasticity and functional recovery do not always occur when needed e.g.

  • The case of H.M. who had his hippocampus removed at the age of 27 and went on to suffer catastrophic anterograde amnesia

  • He never recovered short-term memory function

  • This casts doubt as to the universality of plasticity and functional recovery, as they do not apply in every case

• Much of the research in this field is correlational

  • This means that cause and effect cannot be established

  • It leaves too many unanswered questions e.g. why does grey matter build up in specific brain regions, and what other factors might account for the changes?

• Sample sizes in this research are often small (e.g. Maguire used only 16 taxi driver participants)

  • This limits how confidently findings can be generalised