Blakemore + Cooper

• Background pt1

  1. brain plasticity: the process in which the grey matter of the brain grows + shrinks (structural) or our neurones strengthen or weaken (functional)
  2. cats: physical structure of cat's brain is very similar to that of a human being there4 cats are also very intelligent -> can learn, solve problems, adapt to it's environment, communicate needs
• Background pt2

  1. Hirsch + Spinelli: monocular research of the visual cortex of kittens, found kittens exposed to horizontal lines showed a preference to horizontal contours
  2. what B+C aimed to investigate: wanted to improve H+S + do a binocular study with kittens having both eyes exposed to their environment
• More on Hirsch + Spinelli

  reported early visual experiences (visual cortex of infants) can change neural organisation in kittens. raised kittens with 1 eye viewing vertical stripes + 1 eye viewing horizontal. found out of 21 neurones they were all monocularly driven by one eye + in all but one case, the orientation of the receptive field closely matched the pattern viewed by that eye
• Ethical cost + benefit of using kittens

  + we're able to investigate functional brain plasticity of the visual cortex of human brains w/o exposing human infants to any harm

  -the kittens were exposed to harm as they were kept away from their mother in a strange environment (a cylinder of horizontal or vertical stripes). this breaks the principle of responsibility which may reduce the funding of future psychological research into brain plasticity
• Biological vs behavioural blindness

  • biological = biological changes within the visual cortex
  • behavioural = when a kitten's behavioural changes make it seem like they are blind
• What is the critical period

  the period in human/animal life in which the brain is most vulnerable to change: human = 0-5yrs, cats = 0-3months
• What is the aim

  to investigate the development of the primary visual cortex (in cats) and to find out if some of its properties(functions) such as orientation selectivity are innate or learned (interactionist)

  orientation selectivity = which shape the neuron's respond to
• The sample

  kittens were randomly allocated to one of the 2 conditions

  2 of the kittens (one raised in a horizontal environment + one raised in a vertical environment) were used to study neurophysiological effects

  all kittens were in the critical period of their lives (0-3months) in which the brain is most vulnerable to change
• Research method

  lab experiment with an independent measures design - controlled setting of lab at Oxford university

  IV = horizontal or vertical stripes

  DV = measuring behavioural or physical blindness (quantitative + qualitative)
• Procedure pt1

  • kittens were housed from birth in a completely dark room. from age of 2 weeks they were put in a specialist device for 5 hours a day
  • kitten stood on a clear glass platform in tall cylinder with the entire surface covered in high contrast black and white stripes that were either vertical or horizontal
  • no corners to the environment + the upper + lower limits were beyond view of kittens
  • wore a black collar which restricted their view to 130 degrees so they couldn't see their own body
  • kittens didn't seem upset + sat for longs periods of time inspecting walls of tube
• Procedure pt2

  • routine was stopped after 5 months (which is beyond the critical period where visual deprivation causes physiological defects, Wiesel + Huber found irreversible damage occurs from 3 months onwards)
  • kittens were taken for several hours each week to a small, well lit, furnished room where their visual + physical reactions were recorded
  • at 7.5 months 2 of the kittens (one reared in the horizontal and one reared in the vertical environment) were anaesthetised so their neurology could be examined
• Summary of procedure

  
• Behavioural findings (what the experimenters could see from the kittens)

  1. behavioural blindness was shown: kittens raised in vertical environment couldn't detect horizontally aligned objects + vice versa. both sets of kittens remained blind to contours perpendicular to stripes they lived with
  2. the eyes kitten in the vertical environment only followed + played with a rod if it was held + shaken vertically + vice versa (describe)
  3. some of the kittens' defects were permanent: always followed moving objects w jerky head movements + often tried to touch things well beyond their reach
• Physiological findings (the neurological changes measured by the electrode after 7.5 months)

  1. physical blindness occurred: kittens raised in vertical env had problems with horizontal plane recognition cells firing (electrical messages being sent across the synapse)+ kittens raised in horizontal env had problems with their vertical plane recognition cells firing
  2. in normal cats they'd have a balance of horizontal + vertical visual neutrons. kitten raised in vertical env had no neurones in the horizontal orientation + vertical raised kitten there were no neurones in the horizontal orientation
• Summary of findings

  
• Neurone distribution of each kitten

  This change shows the environmental manipulation changed their brains which shows nurture - the interaction between their visual cortex + their manipulated + restricted environment caused this brain plasticity
• Conclusions

  
• Conclusion example Q

  
• Evaluation table

  
• Key theme Q: what, how, who

  WHAT = B+C wanted to investigate functional brain plasticity of the primary visual cortex in cats + if some of its properties are innate or learned

  WHO = 2 kittens in critical period were randomly selected for the environment with horizontal or vertical stripes

  HOW = kept in a completely dark room from birth, after 2 weeks were taken into a tall cylinder with high contrast black + white vertical or horizontal stripes for 5 hours a day. After 5 months (past the critical period) the routine stopped and the kittens were tested for physical + behavioural blindness
• Key theme Q: finding + link

  FINDING: it was found that after this critical period the kittens raised in a purely horizontal environment had no neurones firing that preferred vertical contours

  LINK: links to key theme of brain plasticity as findings illustrate that the kittens visual cortex plasticised to prefer the environment + visual contours they had been exposed to
• How to answer link to approach Q

  2x buzz phrases with a link

  
• Controls

  • kittens wore a black collar so they couldn't see their own bodies to ensure the kittens only saw the vertical or horizontal stripes
  • housed from complete darkness from birth to stop them seeing anything else other than the stripes
• Extra behavioural findings

  kittens v clumsy

  no startle reflex when object thrust at them but v short lived
• What debates does Blakemore + Cooper link to

  • determinism = suggests that kittens visual cortex development is determined by their early visual experiences of either horizontal or vertical restricted environment during the critical period
  • scientific = B+C have high levels of control (kittens wore collar) + manipulated IV (whether kittens were raised in the vertical or horizontal environment) so C+E can be established (lab experiment). standardised (all kept in cylinder for 5 hours a day)