Brain Plasticity & Functional Recovery Flashcards
(10 cards)
plasticity
Plasticity refers to the brains ability to change and adapt (functionally and physically) as a result of change in the environment, eg. experience, damage, or to meet cognitive demands of new learning
during infancy, brain experiences a rapid growth in synaptic connections, peaking at 15,000 (2-3 years) (Gopnick et al, 1999). this is twice as many as the adult brain.
as we age, rarely used connections are lost (deleted) and frequently used connections are strengthened as part of a process known as ‘synaptic pruning’. this makes the brain a more efficient communication system over time.
recent research suggests these functional and physical changes in neural connections (plasticity) are not restricted to a critical period during childhood but can actually occur at any stage of life
functional recovery of the brain after trauma
following physical injury, or other trauma such as a stroke, unaffected areas of the brain are often able to adapt and compensate for areas of the brain that are lost (neuronal cell death) or damaged - known as functional reorganisation
the functional recovery of the brain after trauma is another example of neural plasticity.
healthy areas of the brain may take over the functions that are damaged/lost.
neuroscientists suggest that this process can occur quickly after trauma (spontaneous recovery) then slow down after several weeks/months.
at this point they may require further rehabilitative therapy to assist their recovery
process of functional recovery
the brain is able to rewire itself by forming new synaptic connections close to the damaged areas.
secondary neural pathways that would not normally be used to carry out certain functions are activated or ‘unmasked’ to enable functioning to continue.
this process is supported by a number of structural changes in the brain:
(1) axonal sprouting
the growth (sprouting) of new axons/ nerve endings from existing neurons which connect with other undamaged nerve cells to form new neuronal pathways.
(2) neural regeneration
the growth of new neuron cells
(3) reformation of blood vessels
(4) recruitment of similar areas on the opposite side of the brain
(eg if Broca’s area damaged, the right side equivalent would carry out its functions and after time, functionality may shift back to the left)
(5) denervation supersensitivity
to compensate for the loss of axons in a pathway the remaining axons become more sensitive (more likely to fire)
BUT, this can result in side effects such as over sensitivity to pain.
factors affecting recover of the brain after trauma
- age
- gender
- Rehabilitative Therapy
- perseverance/resilience
- physical exhaustion
- stress
- alcohol/drug consumption
- IQ/ lower education
- lower socioeconomic background
- age
recent research suggests these functional and physical changes in neural connections (plasticity) are not restricted to a critical period during childhood but can actually occur at any stage of life
HOWEVER, there is a deterioration of the brian in old age and this affects the extent and speed of recovery
Marquez de la Plata et al (2008): following brain trauma, older patients (40+) regained less function in treatment than younger patients. also more likely to decline in terms of function for 5 years following the trauma.
Boyke et al (2008): 60 year olds taught a new skill - juggling - showed increases in grey matter in the visual cortex which then stopped and was revered when practising stopped
- gender
research suggests that women recover better from brain injury as their function is not as lateralised (concentrated in one hemisphere)
Ratcliffe et al (2007) examined 325 patients with brain trauma for their level of response for cognitive skills to rehabilitation.
- Patients were 16-45 at injury, received rehabilitation and completed a follow up one year later.
- None of them had learning problems prior to the trauma.
- When assessed for cognitive skills, women performed significantly better than men on tests of attention/working memory and language, whereas men outperformed females in visual analytic skills
- Rehabilitative therapy
Focused effort results in improvement
Constraint induced therapy: stopping patients from using coping strategies (like body language for communication or using undamaged limbs for tasks) makes them improve via functional reorganisation.
reasons for plasticity
- Learning new skills (meet cognitive demands)
- A result of developmental changes
- Response to direct trauma to area of the brain
- Response to indirect effects of damage such as brain swelling or bleeding (from stroke)
Evaluate: Brain plasticity & functional recovery
- STRENGTHS
P) support from human research: Maguire et al (2000)
E) MRI scanned brains of London taxi drivers and found significantly more volume of grey matter in the posterior hippocampus than a matched control group
E) volume of this area positively correlated with the amount of time they had been a taxi drivers
L) human brain can adapt as a result of learning and experience
P) support from animal studies
E) Kempermann et al (1998) rats placed in complex environments had increased number of new neurons than rats in laboratory cages
E) brain of rats in complex environments had adapted and formed new neurons in the hippocampus (ability to navigate)
L) brain can adapt and change (plasticity as a result of experience)
P) support from case study of Jody
E) severe epilepsy, surgery removed right hemisphere
E) left hemisphere compensated, seizures stopped, walking in 10 days
L) functional recovery is possible due to brain plasticity
E) 3 years old - supports the idea hat younger people are more successful in recovery after brain injury (faster recovery)
P) practical applications: understanding the processes involved in plasticity has contributed to the field of neurorehabilitation
E) following illness/injury, spontaneous recovery tends to slow down after weeks, so forms of physical therapy may be required to maintain improvements in functioning
E) eg. movement therapy, constraint induced therapy (stopping patients from using coping strategies)
L) although the brain may have the capacity to fix itself to a point, further intervention is required to be completely successful (improve real lives)
- scientific research methods eg. objective, lab experiments, scanning, surgery
Evaluate: Brain plasticity & functional recovery
- LIMITATIONS
P) recovery from brain trauma is far more complex (individual differences)
E) certain individuals may have more of an ability to recover from brain trauma than others
E) Elbert et al (2001): adults require far more intensive training than children to produce neural changes in response to brain trauma
E) Schneider et al (2014) patients with a college education were 7x more likely to than those who didn’t finish high school to be disability free one year after brain injury
E) Mathias (2015): IQ and educational background are positively correlated with better outcomes after traumatic brain injury
L) number of factors contribute to brain plasticity and recovery from brain trauma that make it a complex area to study
E) nomothetic - more idiographic approach needed
P) plasticity can have negative consequences
E) Ramachandran and Hirstein (1998) found 60/80% of amputees have developed phantom limb syndrome (experience of sensation in lost limbs)
E) usually unpleasant/painful; due to cortical reorganisation in the somatosensory cortex due to limb loss
L) ethical issues/problematic/socially sensitive to assume plasticity is always useful
- study small samples of unusual ppts (eg case studies of brain damaged patients) eg Jody -> findings cant be generalised; low population validity, difficult to replicate/establish validity
- biologically reductionist ( ignores role of free will/ conscious efforts in recovery after trauma)
