plasticity and functional recovery

• what is functional recovery

  When a function is regained after brain damage, because it is transferred from the damaged brain region to an undamaged brain region.
• first step of functional recovery

  -axon sprouting- When an axon is damaged, it affects its neighbours because they no longer receive input from it.  The neighbouring neurons sprout extra connections to compensate.  This usually happens two weeks after the damage has happened.  If the damaged and new axons do a similar job, then function is more likely to return.
• second step of functional recovery- denervation supersensitivity


  when axons do a similar job to the damaged one they become aroused to compensate for the lost ones.  This can have an unfortunate consequence if they are involved in carrying pain messages, because the pain levels would be increased for the patient.
• third step functional recovery- reformation of blood vessels


  – the brain is very reliant on a good blood supply to bring it oxygen and energy, so it is important for recovery that the blood supply is consistent.
• fourth change functional recovery- recruitment of homologous areas in the other hemispheres

  similar areas in the opposite hemisphere can be used for specific tasks.  This can be temporary or a permanent solution.
• factors that affect recovery rates 1/3

  -perseverance and stress-there is some evidence that if a person assesses that function is lost and does not try to use it, then there is less chance of recovery.  It takes a lot of effort to use something that is damaged and this results in fatigue.  Stress and alcohol consumption also seem to affect the chances of the function being regained (Fleet & Heilman, 1986).

   
• factors that affect recovery rates 2/3

  -age-Marquez de le Plata et al (2008) found that following brain trauma older patients (40+) regained less function than younger ones.  Follow up measurements 5 years later also showed that younger patients had less decline in function.
• factors that affect functional recovery 3/3

  -gender-research suggests women recover better as their function is not lateralised (concentrated in one hemisphere). 
• PLASTICITY research studies - maguire

  taxi drivers have increased plasticity- found that posterior hippocampul volume was correlated w their time as a taxi driver and there was sig diffs, shows that the brain can permanently change in response to frequent exposure to a particular task.
• PLASTICITY RESEARCH SUPPORT

  
  

  draganaski- found differences in posterior hippocampus and prietal cortex from 3 months before their final exams and after
• FUNCTIONAL RECOVERY RESEARCH SUPPORT

  Danielli- Investigated an Italian boy named EB who had most of his left hemisphere removed at age 2 1/2 to remove a tumour. After initial aphasia, his language skills recovered within 2 years, with the exception of some word finding problems. Over the years, the neuropsychological assessments showed that EB's language was near-to-normal and his right hemisphere was able to take over left hemisphere functions such as language and speech. This may have been more of a positive outcome because of his age.
• vililiablanca studied newborns who were born with a severely damaged hemisphere due to genetic problems, illness or birth difficulties.  The medical decision taken in these circumstances is to remove the damaged hemisphere soon after birth.  They found that very few showed any signs of behavioural or cognitive impairments as adults. The functions have been transferred to the healthy hemisphere and during childhood the brain has enough synaptic connections to cope with this dramatic change.  
• AO3


  individual differences- so many diff factors that affect chances of recovery-difficult to advise patients on outcomes of rehabilitation

  objective- fmri -
• plasticity


  refers to the brain’s ability to change and adapt as a result of new experience. Research has demonstrated that the brain continues to create new neural pathways and alter existing ones in response to changing experiences.
• Brain plasticity is present from birth.  During infancy, the brain rapidly grows the number of synaptic connections, peaking at 15000 at around 2 ½ years.  This is twice as many as an adult and reflects the vast amount of learning a baby has to do.  Connections that are unused are deleted and frequently used ones become stronger, this process is called synaptic pruning.
• plasticity -

  Kuhn et al found a significant increase in grey matter in various regions of the brain after participants played video games for 30 minutes a day over a 2 month period. Grey matter is responsible for muscle control and sensory perception skills such as seeing and hearing; memory function; and emotion, speech, decision formation - it also promotes better connectivity in certain subregions of the brain associated with these functions. This suggests that video gaming can change brain structure.