Week 4 Vision Objective 5

Question 1

Dorsal lateral Geniculate Nucleus

Answer 1

receives information from optic nerve

relays information from optic tract to visual cortex via optic radiation (geniculocalacrine tract)

Question 2

which nucleus has 50% optic decussation in optic chiasm

Answer 2

lateral geniculate nucleus

Question 3

nuclear layers of lateral geniculate nucleus

Answer 3

6 layers

II, III, V receives signals from lateral half of ipsilaeral retina
I, IV, VI receive signals from medial half of opposite retina

Question 4

Layers I and II

Answer 4

magnocellular
large neurons
receives input almost entirely from Y ganglia
only black and white

supplies the rapidly conducting pathway to visual cortex
point to point transmission is poor

Question 5

Layers III and VI

Answer 5

Parvocellular layers
small to medium sized neurons
moderate conduction pathway to visual cortex
color vision
input entirely from X type ganglion cells
accurate point to point transmission

Question 6

Dorsal Lateral Geniculate Nucleus “transmission gating”

Answer 6

DLGN regulates how much of the signal is permitted to pass

corticofugal fibers from primary cortex and reticular areas of the mesencephalon

both of these sources are inhibitory and help highlight visual information that is allowed to pass

Question 7

Primary visual cortex

1. other name
2. location
3. signals from macular area
4. signals from peripheral retina areas

Answer 7

1. striated cortex
2. located in occipital cortex
3. signals from macula terminate near occipital cortex
4. signals from peripheral retina areas terminate at or along concentric half circles anterior to the pole, but still along the calcarine fissure

Question 8

of distinct of the primary visual cortex

Answer 8

6

Question 9

what fiber terminates in later IV of the PVC?

Answer 9

geniculocalcarine fibers

Question 10

Organization of IV’s subdivisions (Y and X ganglions esp)

Answer 10

Signals from Y terminate in layer VI calpha

Signals from X terminate in VI c-beta and IV alpha (yes, later 4)

Question 11

PVC organization of neurons

Answer 11

several million vertical columns of neurons

Question 12

Color blobs

Answer 12

special column like areas located among secondary visual areas

receive lateral signals from adjacent visual columns and are activated by color signals

Question 13

Fill in the blank

Signals from two separate eyes enter _____ _____ of columns near _______

Answer 13

alternating stripes

layer IV

Question 14

What role do the cortical areas play in regards to visual signals?

Answer 14

they make sure the visual images “are in register” with each other

also required for stereopsis