plasticity, functional recovery of the brain after trauma, split brain research into hemispheric lateralisation, ways of investigating the brain Flashcards
BIOPSYCH
what is plasticity also referred to as?
neuroplasticity or cortical remapping
what is plasticity?
the brains tendency to change and adapt both functionally and physically as a result of experience and new learning
what happens to rarely used and frequently used connections as we age?
rarely used connections are deleted
frequently used connections are strengthened
what is the strengthening and deleting of connections process called?
synaptic pruning
what happens during infancy according to Gopnick et al.?
the brain experiences a growth in the number of synaptic connections, peaking at approximately 15,00 at age 2-3
can existing neural connections change, and new neural connections form at any time in life due to experience and learning?
yes
who studied the brains of London taxi drivers?
Maguire et al
what did Maguire et al. find?
London taxi drivers had significantly more volume of grey matter in the posterior hippocampus than in a matched control group
what is the posterior hippocampus associated with?
the development of spatial and navigational skills in humans and other animals
what is the learning experience that seems to alter London taxi driver’s brains?
‘the knowledge’- assesses their recall of the city streets and possible routes
what was the positive correlation that Maguire et al. find?
the longer the taxi drivers had been in the job, the more pronounced the structural difference was
who else found similar findings to Maguire et al’s. study? (2 people)
Draganski et al
Mechelli et al
what is functional recovery? is it a form of plasticity?
following damage through trauma, the brains ability to redistribute or transfer functions usually performed by a damaged area(s) to other, undamaged area(s)
yes
what do neuroscientists suggest in terms of how quickly functional recovery happens?
the process of functional recovery can occur quickly after trauma (spontaneous recovery), and then slow down after several weeks or months
how does the brain recover?
it rewires and reorganise itself by forming new synaptic connections close to the area of damage
what do secondary neural pathways that aren’t typically used to carry out certain functions do in functional recovery according to Doidge?
they are activated/’unmasked’ to enable functioning to continue
what are 3 structural changes in the brain that support Doidge’s ideas?
axonal sprouting
reformation of blood cells
recruitment of homolongous (similar) areas
what is axonal sprouting?
the growth of new nerve endings which connect with other undamaged nerve cells to form new neuronal pathways
what does recruitment of homolongous (similar) areas mean?
homolongous (similar) areas on the opposite side of the brain are recruited to perform specific tasks. after a period of time, functionality may then shift back to its original side
what field has plasticity contributed to?
neurorehabilitation
what does neurorehabilitation show regarding plasticity and functional recovery?
although the brain has the capacity to ‘fix’ itself to a point, it requires further intervention if it is to be completely successful
does plasticity have practical applications?
yes
can the brains ability to rewire itself sometimes have maladaptive behavioral (negative) consequences?
yes
does functional plasticity tend to reduce or increase with age?
reduce
who showed that neural plasticity continues throughout the lifespan in a study using golfers?
Bezzola et al
what did Hubel and Wiesel find in their early study on neuroplasticity and functional recovery using kittens and what was their procedure?
they sewed one eye of a kitten shut and analysed the brains cortical responses. the area of the visual cortex associated with the shut eye was not idle, but continued to process information from the open eye
does evidence suggest that a persons educational attainment may influence how well the brain functionally adapts after injury (the more education- the greater the chances of a disability free recovery (DFR))?
yes
what is hemispheric lateralisation?
the idea that the 2 halves (hemispheres) of the brain are functionally different and that certain mental processes and behaviors are mainly controlled by one hemisphere rather than the other
how was hemispheric lateralisation investigated?
using split brain studies
who were the participants in the split brain research?
epileptics who had experienced a surgical separation of the hemispheres in the brain
who conducted the split brain studies?
Sperry
why did Sperry conduct studies on split brains?
to see the extent to which the 2 hemispheres were specialised for certain functions, and whether the hemispheres performed tasks independently of one another
what procedure did Sperry use?
a general procedure in which and image or word could be projected to a patients right visual field (processed by the left hemisphere) and the same or different image or word could be projected to the left visual field (processed by the right hemisphere)
why did Sperry use this procedure on split brain patients?
in the ‘normal’ brain, the corpus callosum would immediately share the information between both hemispheres, giving a complete picture of the visual world. however, presenting the image to one hemisphere of a split brain patient meant that the information could not be conveyed from one hemisphere to the other
what were the findings of Sperry’s study when patients were asked to describe what they could see?
when a picture of an object was shown to a patients right visual field, the patient could easily describe what they saw. if, however, the same object was shown to the left visual field, the patient could not describe what was seen, and typically reported that there was nothing there. this is because language is processed in the left hemisphere, and not the right, meaning they weren’t able to describe what they saw in their left visual field
what were the findings of Sperry’s study when patients had to recognise an object by touch?
when an object were placed in the right hand (processed by the left hemisphere), the patients could verbally describe what they felt, and could identify the test object by by selecting a similar object. when an object was placed in the left hand (processed by the right hemisphere), however, the patient could not describe what they felt and could only make wild guesses. they could identify the test object by selecting a similar object
what were the findings of Sperry’s study when patients were asked to draw what they saw?
when a picture was presented to the right visual field (processed by the left hemisphere), the right hand would attempt to draw the picture but it never came out as clear as the left hand, which shows that the right hemisphere is superior in processing visual motor tasks. the left hand was able to draw a considerably clearer image of the picture, even though all the participants were right handed
what does the split brain research suggest about hemispheric lateralisation?
the left hemisphere is the analyser (analysing, verbal tasks)
the right hemisphere is the synthesiser (spatial tasks, music, contributes emotional and holistic content to language)
was Sperry’s procedure strong or weak? why?
stong
it was a highly specialised and standardised procedure
did Sperry’s work prompt a theoretical and philosophical debate about the degree of communication between the 2 hemispheres?
yes
what did Pucetti suggest?
the 2 hemispheres are so functionally different that it represents a form of duality in the brain- we are all 2 minds
what do other researchers argue (against Pucetti’s idea)?
the 2 hemispheres form a highly integrated system and are both involved in most everyday tasks
are there issues with generalisation in Sperry’s research? why?
yes
unusual participants- split brain epileptics only make up a tiny percentage of the population
how do functional magnetic resonance imaging (fMRI)’s work?
it detects the changes in blood oxygenation and flow that occur as a result of neural (brain) activity in specific parts of the brain. when a brain area is more active it consumes more oxygen and to meet this increased demand blood flow is directed to the active area
what are electroencephalograms (EEG’s)?
a record of the tiny electrical impulses produced by the brains activity. by measuring characteristic wave patterns, the EEG can help diagnose certain conditions of the brain
what are event-related potentials (ERP’s)?
the brains electrophysiological response to a specific sensory, cognitive, or motor event can be isolated through statistical analysis of EEG data
what are post-mortem examinations?
when the brain is analysed after death to determine whether certain observed behaviors during the patients lifetime can be linked to abnormalities in the brain
what are the strengths of fMRIs?
it does not rely on the use of radiation
risk free
non-invasive
straightforward
images are clear, and can easily see how brain activity is localised
what are the weaknesses of fMRIs?
expensive
poor temporal resolution- 5 second lag
what are the strengths of EEGs?
able to diagnose conditions e.g. epilepsy
helped our understanding of sleep stages
high temporal resolution
what are the weaknesses of EEGs?
generalised nature of the information received
what are the strengths of post mortem examinations?
provided a foundation for early understanding of key processes in the brain
improve medical knowledge
help generate hypotheses for further study
what are the weaknesses of post mortems?
causation issues
ethical issues- unable to consent
