Brain Plasticity

Plasticity

Brain’s tendency to change and adapt, functionally and physically, as a result of experience and new learning. It was thought that this process was limited to childhood, and that the adult brain is static and fixed, but research has shown that at any point in life new neural connections can be formed.

Functional Recovery

• Following physical trauma, unaffected areas of the brain often adapt and compensate for damaged areas.

• Functional recovery after trauma is another example of neural plasticity.

• This can happen quickly after trauma, spontaneous recovery, and then slows down after a few weeks or months after which the patient may need rehabilitative therapy.

• the brain is able to rewire and reorganise by forming new synaptic connections close to the area of damage (neural reorganisation)

• secondary neural pathways that would not typically be used to carry out certain functions are activated in order to enable functioning to continue

• full recovery is more likely in younger people, especially children because the brain is still maturing

Axonal Spouting

Undamaged axons grow new nerve endings to reconnect neurons whose links were damaged or severed

Cochlear Implants

Cochlear implants demonstrate how the brain can change and adapt to discern sounds, from when someone puts it in they can’t understand anything, all speech just sounds like noise but over time they can begin to understand as their brain changes and develops new connections

Synaptic Connections

how learning works:

• pruning = where connections are lost due to lack of use

• bridging = where new connections are created due to use and new stimulus

Areas of the Brain involved in creating synaptic connections

• parietal lobe = integrates information from the different sense and plays an important role in spatial navigation

• cerebellum = associated with movement, balance and coordination

• frontal lobe = associated with higher order functions

Kuhn 2014

• got participants to play Super Mario for 30 mins a day for 2 months

• then compared their brain development to a control grouop

• found significant differences in grey matter

Davidson et al 2004

• studied Tibetan monks and compared them to a non-meditation control group

• each group was asked to meditate for a time and were fitted with electrical sensors to detect brain activity (EEG or ERI)

• the monk group showed significantly higher levels of gamma rays

Maguire et al 2000

• studied the brains of London taxi drivers who have to take the knowledge (have to know every street in London) compared to a matched control group (taxi drivers who didn’t have to take the knowledge, not from London)

• found more volume of grey matter in the posterior hippocampus than in a matched control group

• this part of the brain is associated with navigational and spatial skills

• results were correlational

• independent groups design

Draganski et al (2006)

• imaged the brains of medical students 3 months before and after their final exams

• learning induced changes were seen in the posterior hippocampus and parietal cortex

• repeated measures design

Structural Changes during Functional Recovery

• axonal sporuting

• reformation of blood vessels

• recruitment of homologous areas

  • this is where a similar area of the brain on the opposite side is used to perform a specific task

  • after a period of time functionality may shift back

Evaluation

Practical Application

• understanding plasticity has contributed to the development of neurorehabilitation

• following trauma to the brain spontaneous recovery tends to slow down after weeks or months so physical therapy may be needed to maintain improvements in functioning

• techniques include motor therapy and electrical stimulation in the brain to counteract any cognitive or motor deficits

Age and Plasticity

• the brain has a greater ability to reorganise in childhood as it is constantly adapting to new experiences and learning

• this was misinterpreted to mean that plasticity stopped in childhoood, but in reality it just reduces with age

• although, Bezzola at al (2014) found that 40 hours of gold practice produced changes in the neural representation of movement in participants 40-60

• using fMRI the researcher observed reduced motor cortex activity in the novice golfers compared to a control group, suggesting more efficient neural representation after training

Support from Animal Studies

• early evidence of neuroplasticity was derived from animal studies

• pioneering study by Hubel & Wiesel (1963) involved sewing one of a cat’s eyes shut and analysing the brain’s cortical responses

• it was found that the visual cortex of the shut eye continued to process information from the open eye

Cognitive Reserve

• evidence suggests that a person’s educational attainment may impact how well the brain adapts after injury

• Schneider at al (2014) discovered that the more time brain injury patients had spent in education the more likely they were to make a full recovery

• 769 patients were studied - 214 made a disability free recovery after 1 year

• 40% of these DFR patients had more than 16 years education whereas 10% had less than 12 years

• the study was retrospective looking at data from he US Traumatic Brain Injury Systems Data base