Ch.9 CONT, pathway specifics

Question 1

how does the geniculostriate pathway work with each eye?

Answer 1

each eye sends projections to both LGNS, but projections from the two eyes go to different layers: processed separately
IMPORTANT: EACH LAYER ONLY PROCESSES FROM EITHER M CELL OR P CELL, BUT NOT BOTH

Question 2

where does information from the right side of each retina go?

Answer 2

right LGN
information from the contralateral side (the left side) would go to layers 1, 4, 6
information from the ipsilateral side (right side) goes to layers 2, 3, 5

Question 3

striate cortex/V1 layers

Answer 3

ALWAYS IN ROMAN NUMERALS
layers I, II, III: integrate
LAYER IV ALPA: receives from M cells (goes from rods first, then to m cells, then to layer I and II bc that’s the magnocellular layer, then to IValpha)
LAYER IVBETA: receives from P cells; goes from cones first, then to lgn, then layer 3-6, then project to IVCbeta

Question 4

cortical blindness

Answer 4

Cortical blindness is the total or partial loss of vision in a normal-appearing eye caused by damage to the brain’s occipital cortex

Question 5

RGCS

Answer 5

form the optic nerve (outside CNS) and optic tract (inside the CNS)

Question 6

Where does afferent info go in the striate cortex?

Answer 6

incoming, LaYER IV, which can be subdivded into IValpha and IVbeta

Question 7

Milner and goodale, dorsal and ventral vision streams

Answer 7

Dorsal; above “how stream”: shaping hand, visually guided movement, unconscious = if damaged, they can see the object, but can’t appropriately place their hand or get the proper grip
Ventral: what pathway, beneath, vision for identification, assigning meaning to objects, CONSCIOUS, if damaged = not able to put pieces of stimuli together to form a holistic whole, could also translate to facial recognition

Question 8

Visual form agnosia

Answer 8

VENTRAL = TEMPORAL LOBE
damage to the what pathway, which is ventral, object identification
Most common cause: carbon monoxide poisoning
can’t comprehend coherent image or object, but their how stream is functioning totally fine and even if they can’t fully “see” or identify it, they can still place their hands appropriately for a task*****

Question 9

Optic ataxia

Answer 9

dorsal stream damage; S1, PARIETAL LOBE,
deficit in the visual control of reaching and other movements
Can’t shape their hands appropriately to pick up objects correctly,but have good object recognition

Question 10

Patient D.F, lesion areas?

Answer 10

had visual form agnosia

Question 11

what would happen if the right optic tract was damaged?

Answer 11

both eyes have a deficit bc now is past the optic chiasm; the left hemifield for each eye would be completely blind

Question 12

what would happen if the left optic tract was damaged?

Answer 12

both eyes have a deficit bc now it is past the optic chiasm, but the right hemifield for each eye would be completely blind

Question 13

tophat questions?