Blakemore & Cooper

Question 1

What were Blakemore & Cooper studying?

Answer 1

• Brain plasticity
• Does the brain change shape/size?

Question 2

What was the background?

Answer 2

Hubel & Wiesel - stimulated individual neurons in visual cortex and found columns of cells that respond to 1 particular orientation of line, if not used columns disappear.
Hirsch & Spinelli - raised cats so only 1 eye was exposed to horizontal lines, other only vertical, cells monocularly driven instead of binocularly.

Question 3

What were the aims?

Answer 3

• Look further at physiological and behavioural effects of restricted early visual experience on development of cells of visual cortex.
• Consider whether brain development/plasticity occurs due to nurture rather than nature.

Question 4

What were the IV’s?

Answer 4

• Vertical environment
• Horizontal environment

Question 5

What was the DV?

Answer 5

• Visual placing, behaviour differences, neurological responses

Question 6

What was the sample?

Answer 6

• 2 cats, new-born, visual cortex unaffected

Question 7

What materials were used?

Answer 7

• Cylinder (with stripes)
• Ruff around neck (black)
• Stood on transparent platform

Question 8

What was the procedure?

Answer 8

• first 2 weeks, raised in the dark (for normal binocular vision)
• placed in cylinder for average 5 hours a day, in the dark for the rest of the time
• after 5 months, visual deprivation was stopped (visual systems fully developed, past critical period)
• several hours a week cats were placed in well-lit & had chairs and tables
• cats were given artificial lenses to ensure vision differences were not down to astigmatism

Question 9

What happened in the assessments (behavioural & neurophysiological)?

Answer 9

Behavioural:
- observed -> lines on screen, rod waving in front of them, startled reaction, visual placing (reactions to sudden movements)
Neurophysiological:
- 7 1/2 weeks, cats were anaesthetised and temporarily paralysed, tested using electrode inserted in unit (measures electrical firing of each neuron)

Question 10

What are some conclusions?

Answer 10

• brain changes shape due to horizontal & vertical environments (visual cortex)
• nature modified by nurture (bio system fits demand of environment)
• unused part of innate nervous system does not degenerate but adapt to match visual experience

Question 11

What were some results (behaviour)?

Answer 11

• some cats reflexes are normal
• temporary deficit -> visual placing reflex not shown immediately, 10 hours of visual experience has recovered
• permanent deficit -> cats reached out to touch something that was actually far away

Question 12

What were some results (neurological)?

Answer 12

• 75% of cells were binocular and almost responded normally
• responses in certain orientations were abnormal (preferred orientation)
• horizontal didn’t respond within 20 degrees