Plasticity and Functional Recovery of the Brain After Trauma

What is neuroplasticity?

The brain’s ability to adapt its structures and functions based on experience

Brain plasticity

Infancy : the brain experiences a rapid growth in the number of synaptic connections. Approx 15 000 at 2-3 years old. Twice as many as the adult brain

What is synaptic pruning?

Rarely used connections are deleted, frequently used connections are strengthened. Enables lifelong plasticity, new neural connections are formed in response to new demands

Case studies for brain plasticity

Maguire et al 2000 and Draganski et al 2006

Maguire et al 2000 background

Role of the Hippocampus is to facilitate spatial memory, form of navigation

Maguire et al aim

Examine whether structural changes could be detected in the brains of people with extensive experience of spatial navigation

Maguire et al procedure

Taxi drivers training for the Knowledge, made an ideal group for spatial navigation. 16 right-handed male London taxi drivers were compared to scans of 50 healthy right-handed males who didn’t drive taxis. Structural MRI scans were used

Maguire et al findings

Increased grey matter in the taxi drivers brains in right and left hippocampus. Found in the posterior hippocampus. Changes with navigation experience : positive correlation between the amount of time spent as a taxi driver and volume of the right posterior. Longer in the job = more structural differences

Maguire et al conclusion

Provide support for the idea of brain plasticity and suggest experience can change the structure of the brain

Draganski et al 2006

Imaged the brains of medical students 3 months before and after their final exams. Learning induced changes were seen to occur in the posterior hippocampus and the parietal cortex

What is functional recovery?

The brain’s ability to replace lost or damaged functions by using existing brain regions in their place

What happens during recovery?

Brain forms new synaptic connections close to the area of damage. Secondary neural pathways that aren’t normally used, carry out certain functions to enable functioning

What are the structural changes that occur in the brain?

Axonal sprouting, reformation of blood vessels, recruitment of homologous areas

Axonal sprouting

New growth of nerve endings from surviving neurons. The fibres link up with other undamaged cells to form alternative neuronal pathways

Reformation of blood vessels

Damaged tissue stimulates angiogenesis, restoring oxygen and nutrient supply to recovering areas

Recruitment of homologous (similar) areas

Regions in the opposite hemisphere adopt functions of injured zones