brain plasticity: blakemore & cooper and maguire et al Flashcards
blakemore & cooper method?
lab expt, imd
iv: environment reared in (horizontal/vertical)
dv: visuomotor tests and neurophysiological tests
blakemore & cooper sample?
laboratory reared kittens housed in complete darkness until 2 weeks old
randomly allocated to two conditions, one from each condition used for neuro physical tests
blakemore & cooper procedure?
from 2 weeks old to 5 months, the kittens spent five hours a day in their ‘world of stripes’
2m by 46cm cylinder with clear perspex floor 1m up
kittens wore a black collar so they couldn’t see their own bodies
after 5 months, they spent time in a well lit room to be assessed (startle response, visual paw placement, responses to rods held v/h)
125 neurons tested for neuro physical effects
blakemore & cooper behavioural results?
despite normal pupil reflexes to light, kittens displayed visual defects, navigating through touch rather than light, no evidence of visual paw placement
failed to show no startle response and showed fear when reaching the edge of surfaces
a lot of these problems disappeared after 10 hours in a brightly lit room, but some stayed, continuing to bump into furniture and clumsily following objects
kittens only responded to perspex sheets and rods corresponding to their environment
blakemore & cooper neurophysical results?
normal cat has balance of horizontal and vertically dedicated neurons
kittens from vertical environments had no neurons within 20 degrees of the horizontal, and vice versa
blakemore & cooper conclusions?
the difference between horizontal and vertical kittens suggests neurons change in response to their early visual experience
thus, brain development responds to early environmental factors
establishes role of nurture in development of sight (at least for cats)
blakemore & cooper method evaluation?
lab expt, high levels of control
could manipulate & control conditions
environment for assessment of behaviour and materials were also controlled
blakemore & cooper data collected evaluation?
quantitative: results from neurophysical analysis, different conditions can be statistically analysed
qualitative: provides detailed descriptions of conditional responses
blakemore & cooper ethicality evaluation?
complies with home offices laws surrounding research concerning animals, however suffering of the kittens was inevitable and one from each condition was euthanised
ethics of animal research uses bateson’s cube
blakemore & cooper validity evaluation?
highly controlled conditions, kittens in darkness between sessions, can determine cause (the iv) and effect
effects of iv assessed two ways, concurrent validity
blakemore & cooper sampling bias evaluation?
use of cats means that generalisation to humans should be done with caution, issue with population validity
blakemore & cooper link with theme?
links to brain plasticity by demonstrating how a cat’s visual neurons develop an orientation reliant on the conditions they grew up in between the ages of 2 weeks to 5 months
cats who grew up with horizontal stripes develop neurons up to 20 degrees of the vertical, and vice versa
blakemore & cooper link to area?
assumption: all behaviour is first physiological
shows a definite link between the orientation of neurons in a kitten’s brain, and the behaviour this cat exhibits
maguire method?
quasi experiment, imd
data collected via mri for correlational analysis
maguire experimental sample?
16 right handed, male, london taxi drivers
mean age 44 (32-62)
licenced for at least 1.5 years (1.5-42 years, mean - 14.3)
average of 2 years on the knowledge
healthy medical, neurological and psychiatric records
maguire control sample?
selected scans from 50 individuals
all male, right-handed, non-taxi drivers
mean age and range matched to expt group
no one with health problems
maguire procedure?
voxel-based morphometry (grey matter volume)
pixel counting (hippocampal volume in relation to brain size)
counts performed by ‘blind’ expert
correction made to account for different brain sizes, using intercranial volume
maguire vbm results?
taxi drivers showed increase in grey matter in the left and right hippocampi
bilateral increase in posterior hippocampi but bilateral decrease in anterior hippocampi
maguire pixel counting results?
found no difference in overall hippocampal volume of expt and control groups
regional differences were recorded however, with taxi drivers having bigger posterior regions and smaller anterior regions
maguire correlation results?
saw a positive correlation between right posterior hippocampi volume and years as a taxi driver
also found a negative correlation between right anterior hippocampi volume and years as a taxi driver
no correlation for left hippocampus
maguire conclusions?
suggests a relationship between navigational skills and distribution of grey matter in the hippocampi
posterior hippocampus: previously learnt spatial information
anterior hippocampus: encoding new information (also involves post.)
taxi drivers require a mental map of london, which needs an increase in volume
suggests left has a different role to right hippocampus, perhaps to store episodic memory
maguire method evaluation?
highly controlled lab expt
however quasi design could lead to participant variables, although matching minimised this
mri scanning precise and objective, but expensive and machines and technicians have limited availability
correlational analysis can confirm a relationship, but not causation
maguire data collection evaluation?
only quantitative, allows statistical analysis and correlation
however, lacks detail
maguire ethicality evaluation?
carried out to bps guidelines
no deceit, informed consent given, right to withdraw ensured, no harm (bar claustrophobics and those with metal implants)
maguire validity evaluation?
despite quasi nature, ps being matched on age, sex and handedness increased design validity
concurrent validity from pixel counting and vbm
conclusions are supported by the correlation and animal research
no possibility of demand characteristics, so no worry of ecological validity due to lack of a task
blind technicians increased validity of dv measures
maguire sampling bias evaluation?
androcentric, can’t assume male and female brains function the same way
spatial memory of left and right handed people may work differently
taxi drivers chosen may be those more adaptable to the knowledge as they all completed it with an average of 2 years
maguire link to theme?
links to theme of brain plasticity by showing how an adult brain can adapt to the environmental demands placed upon it
in this case, it was the taxi drivers brains developing a larger posterior hippocampus and smaller anterior hippocampus
maguire link to area?
focuses on brain structures, functions and these can change under certain conditions
studied the neuroplasticity of taxi drivers and demonstrating how different regions of the hippocampi react to having to accomodate large amounts of spatial information
blakemore & cooper and maguire similarities?
both highly controlled lab expts
both produce objective, quantitative data from biological means
blakemore & cooper and maguire differences?
maguire is a quasi expt and blakemore & cooper was a true expt
maguire studied human brains and blakemore & cooper studied kittens
