plasticity and functional recovery of the brain after trauma

Brain plasticity definition

The brain’s ability to modify neural pathways and synaptic connections as a result of environmental stimuli. this can happen in three ways

1. experience expectant plasticity

2. Experience dependent plasticity

3. Functional recovery

structural and functional plasticity

Structural plasticity is everyday event that shape our brains development

Functional plasticity is the brains ability to move functions from damaged areas to undamaged areas

three forms of plasticity

Synaptogenesis

Neurogenesis

Synaptic pruning

Synaptogenesis

When new synapsis are formed. This can occur throughout life, but during infancy there’s an explosion of synaptic formation known as exuberant synaptogenesis.

neurogenesis

this refers to when new neurons are grown. In infancy this is responsible for populating the growing brain with neurons but also occurs in adulthood.

synaptic pruning/axon pruning

The process of synapse elimination that typically happens between early childhood and onset of puberty. However, this has also been showing occur to less extent in adulthood.

experience expectant plasticity and experience dependent plasticity

experience expectant plasticity: infancy

experience dependent plasticity: black cab taxi drivers, gamers, astronauts spending months in space

Infancy

EEP

Brain experiences rapid growth in the number of synaptic connections it has, approximately 15000 by age 2 to 3 years old, synaptogenesis . Twice more than adults.

Computer gaming

EDP

kuhn et al

Benefits of playing super Mario for two months, 30 minutes each day

Increase new connections in brain specifically hippocampus (navigational learning) prefrontal cortex (cognitive processes) cerebellum (visual – motor)

Synaptogenesis

taxi driving

EDP

Maguire et at 2000

Studied London taxidrivers using MRI and found significantly higher grey matter in posterior hippocampus than non-taxi drivers

this part developed spatial and navigational skills. The knowledge test to assess recall of city and routes.

astronaut spending months in space Station

Koppelmans et al 2016

effect of no gravity affecting the brain

27 astronaut scanned before and after space mission

Between two weeks, a.k.a. six months in space, cerebellum shrunk and motor and somatosensory region swelled

functional recovery

the brain's ability to redistribute or transfer functions that were usually performed by a damaged area to other, undamaged areas of the brain.

Occurs with trauma such as an infection eg. meningitis or experience of a stroke

Me experience loss of brain function including paralysis, aphasia (language difficulty), memory loss (amnesia) or perception difficulty

1. neural regeneration

2. neuronal unmasking

3. neural re-organisation

Neural plasticity and spontaneous recovery

neural plasticity is when unaffected areas are sometimes able to adapt or compensate for those areas that are damaged. Spontaneous recovery is when it happens quickly after trauma and then slows down after several weeks or months.

neural regeneration

A.k.a. axon sprouting

Occurs when new endings grow and connect with undamaged areas

This can compensate for damaged areas and enable the recovery of previously lost function

Can be seen as synaptogenesis

neuronal unmasking

this occurs when dormant synopsis in the brain (exist anatomically but are blocked from functioning ) are opened and become functional

This can occur when a surrounding brain becomes damaged as the rate of input to these dormant synopsis would increase opening connections to regions of the brain that are not normally activated and allowing gradual development of new structures

This can be seen as a type of synaptogenesis/neurogenesis

neural re-organisation

This occurs when the brain transfers functions from the damaged area to undamaged sections of the brain

For example, if broca’s area in the left hemisphere was damaged than an area on the right hemisphere may take over. In extreme cases and with intensive therapy, whole errors of the brain can take over the functions of damage sections.

research support Danelli 2013

Danelli investigated the case of an Italian boy who had most of his left hemisphere removed each 2 1/2 to remove a tumour

With intensive therapy, his right hemisphere was able to take over almost all of the functioning like language and speech, that would normally have been done by the left. This is largely because his brain would have shown maximum plasticity.

evaluations

1. there are supporting research, Danelli 2013

2. Case study lacks population validity as it is not generalisable and androcentric

3. Limited in explaining complexity of recovery, recovery from brain trauma is not universal. eg women have esteogen and are more likely to functionally recover

4. Practical application in researching dementia

5. Maladaptive as prolonged drug use can result in poor cognitive functioning and an increased risk of dementia