Visual perception & photoreception

Question 1

Q: Definition of the Full Visual Field?

Answer 1

A: The total space visible without moving the eyes or head

Question 2

Q: Where on the retina does the Fixation Point fall?

Answer 2

A: The Fovea (central point of the macula)

Question 3

Q: Where is the Optic Disc (Blind Spot) located on the retina relative to the Fovea?

Answer 3

A: Approximately 15∘ medial (nasal) to the fovea

Question 4

Q: How does the image appear when projected onto the retina?

Answer 4

A: It is inverted and reversed

Question 5

Q: The general rule for visual information processing in the brain?

Answer 5

A: Information from the left and right visual fields (from both eyes) is processed on the contralateral side of the brain

Question 6

Q: Which retinal half relays the temporal visual hemifield?

Answer 6

A: Nasal retina

Question 7

Q: Which retinal half relays the nasal visual hemifield?

Answer 7

A: Temporal retina

Question 8

Q: What happens to Nasal retinal fibers at the Optic Chiasm?

Answer 8

A: They cross to the contralateral optic tract

Question 9

Q: What happens to Temporal retinal fibers at the Optic Chiasm?

Answer 9

A: They remain on the ipsilateral optic tract

Question 10

Q: What structure sits directly inferior to the Optic Chiasm?

Answer 10

A: The Pituitary gland

Question 11

Q: Which two fiber types does the Optic Tract carry?

Answer 11

A: Contralateral nasal retina fibers and ipsilateral temporal retina fibers

Question 12

Q: What is the relay station where retinal axons synapse post-chiasmally?

Answer 12

A: Lateral Geniculate Nucleus (LGN) of the thalamus

Question 13

Q: Location of the LGN in the thalamus?

Answer 13

A: Posterior portion of the thalamus; posterior to the optic tract

Question 14

Q: Which LGN layers handle Motion and Spatial analysis (M channel)?

Answer 14

A: Layers 1-2

Question 15

Q: Which LGN layers handle Detailed form and Color (P channel)?

Answer 15

A: Layers 3-6

Question 16

Q: Where do the Superior Optic Radiations travel and terminate?

Answer 16

A: They run through the Parietal lobe and terminate in the superior bank (Cuneus) of the Calcarine fissure

Question 17

Q: What is the loop of the Inferior Optic Radiations called?

Answer 17

A: Meyer’s loop

Question 18

Q: Where do the Inferior Optic Radiations travel and terminate?

Answer 18

A: They run through the Temporal lobe (Meyer’s loop) and terminate in the lower bank (Lingula) of the Calcarine fissure

Question 19

Q: What is the Primary Visual Cortex also called?

Answer 19

A: V1, Area 17, or the Striate Cortex

Question 20

Q: Where is the Primary Visual Cortex located?

Answer 20

A: Lies on the banks of the Calcarine fissure in the occipital lobe

Question 21

Q: What visual field is represented by the posterior 1/3 of the visual cortex?

Answer 21

A: Macular representation (central vision)

Question 22

Q: Function of the Ventral Visual Stream (The “What?”)?

Answer 22

A: Analysis of form, color, faces, and patterns. Projects to the occipitotemporal association cortex

Question 23

Q: Function of the Dorsal Visual Stream (The “Where?”)?

Answer 23

A: Analysis of motion and spatial relationships. Projects to the parieto-occipital association cortex

Question 24

Q: Main blood supply to the visual cortex (V1)?

Answer 24

A: Posterior Cerebral Artery (PCA)

Question 25

Q: Artery supplying the Ventral Stream (Occipitotemporal cortex)?

Answer 25

A: Posterior Cerebral Artery (PCA)

Question 26

Q: Arteries involved in the Dorsal Stream (Parieto-occipital cortex)?

Answer 26

A: Lies in the MCA-PCA watershed territory, making it vulnerable to ischemia

Question 27

Q: Lesion at: Optic Nerve (Pre-chiasmal) results in

Answer 27

A: Ipsilateral Monocular Vision Loss (Monocular Blindness)

Question 28

Q: Lesion at: Optic Chiasm results in

Answer 28

A: Bitemporal Hemianopia (loss of both temporal visual fields)

Question 29

Q: Lesion at: Optic Tract (Post-chiasmal) results in

Answer 29

A: Contralateral Homonymous Hemianopia (loss of the entire contralateral visual field)

Question 30

Q: Lesion at: Inferior Optic Radiation (Meyer's loop) results in

Answer 30

A: Contralateral Superior Quadrantanopia ("Pie in the sky" loss)

Question 31

Q: Lesion at: Superior Optic Radiation results in

Answer 31

A: Contralateral Inferior Quadrantanopia ("Pie on the floor" loss)

Question 32

Q: Lesion at: Primary Visual Cortex (V1) results in

Answer 32

A: Contralateral Homonymous Hemianopia (often with macular sparing)