Visual Plasticity

Question 1

What is amblyopia

Answer 1

lazy eye

Question 2

How does the Ocular Dominance column develop in the eye?

Answer 2

• Before birth, retinae produce waves of synchronous activity that drive the cortical cells well
• After birth, visual input drives coordinated retinal activity
• The afferents from each eye fire in synchrony, independent of the other eye
• Synapses are either weakened or strengthened depending on the relative amount of input from each eye

Question 3

How are synapses strengthened during OD development?

Answer 3

• if cell releases glutamate and is part of synchronous circuit other synapses will also release glutamate
  ◦ cell depolarises
• shows synapse part of useful depolarisation
• strengthens synapse
• each cell of cortex will be separate

Question 4

How can OD shrinkage occur?

Answer 4

• Before birth, retinae produce waves of synchronous activity that drive the cortical cells well
• After birth, visual input drives coordinated retinal activity
• The afferents from each eye fire in synchrony, independent of the other eye
• OD columns will segregate in response

HAPPENS WHEN ONE EYE IS COMPROMISED BEFORE BIRTH

Question 5

What is monocular deprivation and its critical period?

Answer 5

• in humans, OD column shift can be reversed
• visual pathway somewhat plastic for around 7 yrs
  ◦ once OD columns have shifted, hard to shift back
• treatment involves patching good eye and persuading child to do work w bad eye for at least 2hr a day