Blakemor & Cooper

define neuroplasticity

neural pathways adapt, depending on experiences such as learning & injury. When neural pathways are used, they strengthen & when new things are learnt, they expand. This is called neural growth. When pathways aren't used, they might be "deleted". This is called neural pruning. 

what debates does neuroplasticity relate to, how?

• link to nature vs nurture - upbringing (nurutre) can change/rewire your brain (nature)

• free will vs determinism - your brain can be re-wired - behaviour can be changed

What are the 2 background studies for Blakemor & Cooper?

Hubel & Wiesel

Hirsch & Spinelli

what did Hubel & Wiesel find?

Hubel & Wiesel (1962) found all normal adult cats have neurons in V1 (primary visual cortex) (located in the same region as the human brain) that respond to all orientations of line received from both eyes, suggesting this may be an innate (since birth) perceptual ability. 

what did Hirsch & Spinelli find?

Hirsch and Spinelli (1970) however, found that kittens, reared with one eye viewing vertical stripes and the other horizontal, had neurons in V1 which responded to only one eye and only to the orientation of line that eye had experienced (measured using an electrode implanted in the kitten’s brains). This suggested early visual experience (nurture) had an influence on visual perceptual abilities and the development of V1 that controls visual perceptual functions.

what is the role of the primary visual cortex (V1)?

processes visual info received through the eyes (e.g. motion)

what was the aim of the study and what did it test?

To investigate how early visual experience, using normal binocular (using both eyes to see) vision, affected kitten’s perception of different orientations of line (which direction the line is; vertical/horizontal).

This tested whether the orientational selectivity of neurons in V1 was innate or acquired through nurture.

outline the sample

Kittens (don't open their eyes until 7 days) raised in the dark from birth, and then experimented on from 2 weeks to 7 ½ months. Only 2 were used for the neurophysiological tests (1 from each condition). 

How generalisable are the results of this study on the neuroplasticity of V1 in kittens to human infants?

It is not generalisable as most animals are born with instinctive abilities (e.g. walking). The organisation of their motor cortex & visual perceptual systems are likely innate so they don't have to learn this ability. As humans most of our abilities are learnt.

outline the procedure

All kittens were kept in the same completely dark environment from birth, and then at 2 weeks were exposed to only horizontal OR vertically lined, lit environments, using the same equipment. At 5 months, the kittens’ visual perception (visuo-motor behaviour) was observed for several hours each week in a well-lit room with tables and chairs: this included recording their response to vertically and horizontally shaken sticks (whether they tracked the object with their eyes). They then measured the function of V1 (neuro-physiological results) using electrodes at 7 ½ months. ​At 7 1/2 months, 2 of the kittens (one reared in the horizontal, the other vertical) were anaesthetised so their neurophysiology could be examined (preferred orientation of neurons in the V1 region).

what method was used?

lab exp

what experimental design was used?

independent measures design

what was the IV?

vertical lines or horizontal lines environment 

what was the DV?

• visual perception - whether they tracked the verticallly/horizontally shaken sticks with their eyes)

• function of V1

what were the controls of the study?

kittens raised in complete darkness to ensure kittens all start exp w/ no vision (dark so can't see)

what were the visuo-motor observational findings and conclusions?

Initially all kittens showed deficits in somevisuo-motor functions but recovered them within 10h of visual experience in a normal environment. Could not percieve opposite orientation. Each visuo-motorr ability they were initially lacking;

• startle response - caused kittens to flinch when stick shaken in front of them

• visual placing - placed arms/legs to protect themselves after being placed on the edge

This supports nature vs nurture bc they responded to an environment that they learned they should protect themself from: stick and edge of table

• gained back visuo-motor skills after

• critical period of biological maturation

• artifical env - negatively impacted visuo-motor functions

• However, some deficits were permanent: 

  • Kittens were clumsy when trying to track an object (follow its movement) and they often reached for objects out of their reach suggesting an issue with depth perception.

  • The results of tests on their ability to respond to visual stimuli of different orientations showed that kittens raised in a horizontal environment didn’t follow a stick with their eyes when it was being shaken vertically, and vice versa for vertically raised cats.

This supports nature & nurture bc kittens aquired through visual experience in a critical period of biological maturation.

what were the neurophysiological findings and conclusions?

• The two cats who were operated on showed abnormal neurophysiological development. The cat raised in a horizontal environment had neurons which selectively responded to horizontal orientations, and vice versa. This meant that their brains could not process any edges or lines in their environment which were oriented differently to the orientation of the lines in the environment which they had been raised.

  • No neurons which responded to any line within 20 degrees of the orientation the cat had never been exposed to.

  • There was no region of silent neurons found: there were not areas of neurons which showed no response to any visual stimuli. This suggests there aren’t neurons ready to respond to horizontal or vertical orientations that are just turned on/off by experience. The neurons change/adapt their function (what they respond to) based on the visual experience the kitten receives early on.

• Unlike Hirsch and Spinelli (1970), who had shown different visual stimuli to each eye of their cats, Blakemore and Cooper (1970) found that the majority of neurons (75%) responded to binocular information (visual information received from both eyes). 

evaluate the research method and technique

• lab conditions; extraneous variables controlled (e.g. kittens' first 2 weeks artifical completely dark room

• artifical env may act as an extraneous variable itself - may be the distress caused by the experience that affected the development of the kittens - this means the effects of visual deprivation observed in this study may not generalise everyday experiences. 

evaluate the validity of the study

• high internal validity - lab exp; highly controlled env

• clear cause & effect b/n visual experience & perception

evaluate the reliability of the study

• both cats responded in an almost identical way to the orientation of their rearing suggests consistency

what type of data was collected, how?

• quantitative data - reaction of neurons to orientation of lines, allowed comparison between cats

• qualitative data - observations made of cats in a well-lit env, such as tripping over table legs

evaluate the ethical considerations of the study

• kittens may have been affected by their visual and physical isolation - not protected from harm