Blakemore and Cooper (classic study) Flashcards
What is neuroplasticity?
The idea the brain can undergo functional/structural changes such as changes in neurones orientation or size in response to an external stimuli
What was the name of background research to this study?
Hirsch and Spinelli
Hirsch and Spinelli research outline
Used a kitten wearing goggles: one eye exposed to vertical stripes/one eye exposed to horizontal stripes
Hirsch and Spinelli findings
Neurones in the visual cortex preferred orientation of the stripes the eye saw: seeing horizontal stripes meant the neurones had changed direction to reflect this thus mainly saw horizontal contours
2 aims of this study
Compare behavioural differences in 2 kittens raised in a horizontal striped environment from birth to a vertical striped environment
Complete neurophysiological study by inserting rods into cats visual corset to measure orientation of neurones
2 aims of this study
Compare behavioural differences between 2 kittens raised in a horizontal striped environment from birth to a vertical striped environment
Investigate neurophysiological effect on neurones in the kittens visual cortex due to raising them in different environments
What type of experiment is this?
Lab experiment, had an independent variable manipulated by the researcher and controls
Independent variable
The orientation of stripes in the environment each kitten was raised in, either horizontal or vertical
List of controls
Time spent in the cylinder
Same width of cylinder
Both kept in a dark room when not in a cylinder: not exposed to any other light
Kittens used from birth (same method of raising the kittens)
Experimental design
Independent measures
Why was this study independent measures?
Because each kitten only went through one condition of being raised in either the horizontal or vertical striped cylinder and were not then repeating the experiment in the other condition
2 dependent variables
The behaviour of kittens once put into a normal environment (qualitative)
The orientation of the neurones of kittens in the visual cortex (quantitative)
How were the kittens raised in the first 2 weeks of their life?
In a completely dark room with no exposure to light: no external effect on the orientation of neurones in the visual cortex
General procedure
Depending on horizontal/vertical striped condition, kitten was put in the cylinder for 5 hours every day for 5 months
So only light exposed to was different striped orientations
And spent the rest in complete darkness
What was the cylinder like?
Same height and radius for both kittens
Illuminated stripes depending on condition
Glass platform to reflect stripes below them
Lid on top so could only see stripes
What were the kittens wearing in the cylinder?
A black collar to limit vision of their body to only see stripes
After the 5 months, what did the researchers do to observe behaviour of kittens?
Put in a well lit room with furniture (standardised for both kittens) to see how they behave
How many kittens were used in this study?
2
1 in each condition (saw either striped or vertical illuminates stripes in the cylinder)
2 Observations of when the kittens were put in their own room that disappeared after 10 hours
Had no startle response when an object was thrust toward their face
Did not show visual placing
What visual deficits did not disappear from the cats?
Virtually blind to contours perpendicular to the orientation of lines they experienced in the cylinder
What visual tests were done to test kittens visual deficits to seeing contours?
Shaking a rod in various directions
Presented a sheet of black and white lines in different orientations
Results for presenting a sheet of black and white lines to kittens
If the lines were horizontal shown to kitten in vertical cylinder, they had no reaction (blind to it)
If the lines were vertical shown to kitten in horizontal cylinder, they had no reaction (blind to it)
But would react if the lines were in same orientation to which they were raised
Investigating the actual orientation of visual neurones
By completing procedures to investigate the angle at which visual neurones preferred contours (thus could actually see) in these 2 kittens compared to a normal kitten: involved inserting electrodes
Visual neurones in a vertical striped raised kitten
No visual neurones preferred the horizontal orientation: explains why they could only see vertical contours
Visual neurones in a horizontal striped raised kitten
No visual neurones preferred the vertical orientation: explains why they could only see horizontal contours
Conclusions of the study
Visual stimuli can have consequences on the structural development of the brain:
Kitten raised in vertical striped environment only had neurones that preferred vertical orientations thus could only see them
Which effects behaviour (observations)
Evidence for brain plasticity
3 animal rights ethics
Replacement
Reduction
Refinement
Replacement ethics
If animals can only be used because it would be too unethical to experiment on humans
Reduction ethics
Keep the number of animals experimented on at a minimum
Refinement ethics
The severity of any procedures is limited
Evaluate the replacement ethics in this study
This study that investigates how the brain’s structure changes from birth would be way too unethical to complete on human babies
Evaluate reduction ethics in this study
The minimum number of 1 kitten per condition (2 kittens) were used
Evaluate the refinement ethic in regard to this study
The kittens were only trapped for 5 hours and not the whole day
Observing neurones did not kill the kitten and they were anaesthetised (little pain)
Criticise animal ethics of this study
The findings have little benefit to humans (limited practical applications) so may not outweigh the long term visual deficits these kittens were given
This is also because findings may not apply to humans (?)
