Physiology: The Visual Pathway

Question 1

Which optic radiation carries fibres from the superior retinal quadrants (corresponding to the inferior visual field quadrants) through the parietal lobe to reach the visual cortex?

Answer 1

Upper optic radiation

Question 2

Which optic tract contains fibres from the right temporal retina, and the left nasal retina?

Answer 2

Right optic tract

Question 3

What is Hebb’s postulate?

Answer 3

Claims that correlated activity between presynaptic and postsynaptic cells strengthens synaptic connections between them - ‘cells that fire together, wire together’ Can explain the loss of binocularity in infant patients with untreated wandering eye

Question 4

Within the middle cranial fossa, the optic nerves from each eye unite to form the _____ _______

Answer 4

Optic chiasma

Question 5

What is the lateral geniculate nucleus (LGN)?

Answer 5

Relay system located in the thalamus which receives fibres from each optic tract and then sends out axons to reach the visual cortex via the optic radiation pathways

Question 6

Which optic radiation carries fibres from the inferior retinal quadrants (corresponding to the superior visual field quadrants) through the temporal lobe to reach the visual cortex?

Answer 6

Lower optic radiation

Question 7

Projections from the LGN arrive in which layer of the primary visual cortex?

Answer 7

Layer 4

Question 8

Why must you ensure an infant patient with strabismus (wandering eye) wears an eye patch until they are old enough for corrective surgery?

Answer 8

To prevent amblyopia - makes sure the brain develops properly to process signals coming from both eyes

Question 9

Describe the lasting impact of congenital cataracts once the cataracts have been removed

Answer 9

Patients will have difficulty perceiving shape and form due to having impaired vision from birth until removal - visual pathway does not form properly

Question 10

Which optic tract contains fibres from the left temporal (lateral) retina, and the right nasal (medial) retina?

Answer 10

Left optic tract

Question 11

Nerve fibers from the _____ half of each retina cross over at the optic chiasm

Answer 11

Nasal

Question 12

Both eyes project to each visual cortex of the brain, but at the primary visual area, they remain largely segregated into ocular _____ _______ - each column is dominated by input from one of the two eyes

Answer 12

Dominance columns