Core study ten- Blakemore and Copper (Biological area) Flashcards
Background
Blakemore & Cooper were interested in investigating brain plasticity.
Brain plasticity - your brain adapts and changes according to what you do in your life.
Blakemore & Cooper were inspired by the work of Hirsch & Spinelli. They were interested in neurons in the visual cortex of the brain.
They found they could change the way the neurons in the visual cortex aligned themselves by controlling what kittens could see as they grew up.
Kittens were raised could only see vertical stripes in one eye and horizontal stripes in the other eye.
When the cats were then released into an everyday environment, the researchers found that they had visual impairments.
Visual cortex
the part of the brain that receives and processes sensory nerve impulses from the eyes
Startle response
The ‘backing off’ reaction of a cat when an object is moved quickly towards their face
Visual placing
When a cat puts its feet out to meet the edge of a surface
Overall aims
The aim was to investigate how being raised in a visually restrictive environment would affect the visual brain development of cats.
- Compare the behavioural consequences of raising kittens seeing only horizontal or vertical stripes.
- Investigate the neurophysiological effect on neurons in kittens’ visual cortex (brain plasticity)
Sample
2 kittens from birth until approximately 1 year of age.
Procedure
The first two weeks- The newborn kittens were kept in a completely dark room for the first 2 weeks of their life
2 weeks to 5 months- From the age of two weeks, the kittens were placed in a cylinder for 5 hours a day (and returned to the
darkened room for the rest of the day). The cylinders were 2m high and about 46cm in diameter. The
cylinders were made up of a series of black and white vertical or horizontal stripes of varying widths, with each kitten being placed in one of these environments.
At 5 months- The kitten was taken into a well lit room with furniture to be test their behaviour
Controls of the experiment
The kittens had identical visual environments, apart from the lines being vertical or horizontal.
The cylinders were the same size
The kittens spent the same length of time in the cylinders
They both wore a collar
They could move about freely in the cylinder
They were kept in the dark when not in the cylinder
Research method
Lab Experiment
IV
The Independent Variable was the orientation of the stripes within the cylinder (either horizontal or vertical)
Experimental design
As each kitten was exposed to a different striped cylinder the experimental design was independent measures
Behavioral results
The cats initially showed visual deficits when taken into the well lit room
They navigated around the room by touch
They were generally clumsy
They had normal pupillary reflexes
They had no startle response
They had no visual placing
After ten hours of exposure of the well-lit surroundings-what changed and what deficits did the kittens still show.
Deficits they quickly recovered from:
Visual placing
Startle response
Jump easily from chair to floor
Deficits that remained:
There tracking of visual objects was clumsy, jerky head movements and they often tried to reach for objects moving across the room and way out of their reach. They often bumped into things.
How did the vertical and horizontal cats differ
The cats were virtually blind to objects which were in the opposite orientation to the environment they were exposed to (i.e. the kitten raised in the vertically striped cylinder could not see horizontal lines and vice versa).
A sheet of perspex glass with thick black and white lines was held in front of them. If presented to them in the wrong orientation (e.g. vertically for the horizontally raised kitten), they would not respond but would show fear when held in the correct orientation.
A rod was shaken in front of them. The kittens would try to follow and chase the rod but only when it was held in the same orientation as the environment the kitten had been exposed to
Neurophysiological Findings
Results from the scans showed that the visual neurons within the visual cortex had aligned themselves to match the environment the kitten was brought up in. There were little to no neurons aligned to the opposite direction (For example the cat brought up within the horizontal cylinder had neurons aligned within a horizontal arrangement).
This is because the cats had no need for neurons in the other direction and therefore these were moved elsewhere.
