Plasticity and functional recovery of the brain after trauma

plasticity

the brain changing its structure and functioning in response to learning e.g. new synaptic connections are formed or lost 

functional recovery

the brains ability to transfer functions of a damaged part of the brain to another part of the brain after traumatic brain injury

synpatic pruning

Rarely used connections are deleted and frequently used ones are strengthened

neural connections can be maintained, formed or changed by what?

As a result of learning and experience

Spontaneous recovery

Healthy brain areas take over functions of areas that are damaged which will happen quickly after trauma and then slow down after several weeks or months 

What three things could happen during functional recovery?

1. Axon spouting

2. Denervation super-sensitivity

3. Recruitment of homologous (similar) areas in the opposite hemisphere

Axon sprouting

New nerve endings grow and connect with undamaged neurons to form new neural pathways 

Denervation super-sensitivity

neurons that do a similar job become aroused to a higher level to compensate for the ones that are lost (unfortunately can sometimes result in over sensitivity to messages such as pain

Recruitment of homologous areas in the opposite hemisphere

is an area in one hemisphere is damaged the similar area in the opposite hemisphere is likely to take over e.g. Broca’s area get damaged then the similar area in the right hemisphere often takes over speech production. Functionally may then shift back to the left hemisphere over time

Outline Draganski study for supporting plasticity 

found that medical students Brian scans showed larger posterior hippocampuses after final exams than compared to three months prior to their final exams. This suggests that the brain is changing as the students are learning and revising content. Draganski study is more valid than maguire so provides more credibility to plasticity. This is because Draganski scanned participants brans before and after the final exams so we can establish a cause and effect relationship between learning and the size of parts of the brain whereas magire only studies the brains after participants became taxi drivers

Supporting evidence for plasticity

Maguire found that London taxi drivers had larger hippocampus’s than the control group of healthy males who were not taxi drivers. Suggests that hippocampus codes for spatial memorie. Maguire additionally found that there was a positive correlation between the size of the taxi drivers hippocampus and the amount of years they had been a taxi driver. This suggests that the increased spatial memories has caused the volume of the hippocampus to increase adding credibility to the idea of plasticity. However, Maguire had not measured the size of participants hippocampuses prior to becoming taxi drivers so we cannot be sure they didn’t originally have larger hippocampus’s prior to the study which made them a better fit for the job potentially. Therefore, we cannot establish a cause and effect relationship so the study may not add credibility to plasticity.