Visual Cortex and Animal Experiments

Question 1

Visual cortex

Answer 1

The visual cortex is the region of the cerebral cortex where visual information is processed

Question 2

What develops after birth in neurones in the visual cortex

Answer 2

-Soon after birth, neurones in the visual cortex of young mammals form connections, or synapses, allowing them to transfer and process visual information in the visual cortex

Question 3

What needs to happen during the critical period + explanation of why this needs to happen

Answer 3

-Both eyes need to be visually stimulated in order for the neurones in the visual cortex to be correctly organised during this early period (critical period)
-Synapses that pass on nerve impulses during the critical period are strengthened and become a permanent parts of the structure of the visual cortex
-Synapses that do not pass on nerve impulses during the critical period are lost and cannot be reformed

Question 4

What is the result if not enough visual stimulation is provided during the critical period

Answer 4

-Can result in blindness in one or both eyes if there is inadequate visual stimulation during the visual period

Question 5

Why are animals often used in brain research

Answer 5

-The brain is difficult to study as brain tissues are delicate and easily damaged
-Many brain regions work together to carry out particular functions, so it is difficult to study them in isolation
-This is why animal models are used often when studying the brain
-Some animals have similar brain structures to humans so results from these models can be reasonably applied to human brains
-Many people believe that experimenting on animals for medical reasons is more ethical than experimenting on humans

Question 6

What did Hubel and Wiesel study

Answer 6

-Hubel and Wiesel studied the effect of depriving various animals of vision in one eye and the devlopment of the visual cortex

Question 7

Hubel and Wiesel Procedure with the kittens

Answer 7

-Hubel and Wiesel used kittens as their first animal model
-soon after birth, they stitched the kitten’s eye closed, meaning it could only see out of one eyes

Question 8

Findings (including ocular dominance columns)

Answer 8

-They found that after three months, the kittens were blind in the eye that had been stitched shut
-When the researchers looked at the neurone activity in the visual cortex, they found that the ocular dominance columns corresponding to the eye that had been stitched shut were smaller than normal, while the ocular dominance columns corresponding with the open eye were larger than normal

Question 9

Conclusions

Answer 9

-Hubel and Wiesel concluded that the ocular dominance columns in the blinded eye redistributed to correspond to the open eye

Question 10

What are ocular dominance columns

Answer 10

-Ocular dominance columns are groups of neurones in the visual cortex that only respond to input from one eye or another
-Right ocular dominance columns only respond to input from the right eye and left ocular dominance columns only respond to input from the left eye

Question 11

Research repeated using adult cat models and monkeys

Answer 11

-They found that a three month deprivation of vision in one eye led to no loss of vision and no redistribution of ocular dominance columns
-The results were also replicated in baby and adult monkeys, demonstrating the essential nature of light stimulation to the visual cortex during the early months of development
-Without early stimulation to the visual cortex during the early months of development, the ocular dominance columns do not develop correctly