Vision 4 Flashcards
What is the term for the loss of half the visual field?
Hemianopsia
The visual field is bisected into right and left sides, each side projecting to the contralateral side of the brain. How is this done? (2)
Partial dessucation of ganglion cell axons in the optic chiasm and right and left visual fields project to opposite lateral geniculate body and primary visual cortex.
What is the type of hemianopsia that results in loss of opposite visual fields?
Heteronym opus
Where would the lesion be for someone with heteronymous hemianopsia?
Lesion of the central optic chiasm (pituitary tumors)
What is the type of hemianopsia that results in loss of opposite visual fields?
Homonymous
Where would the lesion be for someone with homonymous hemianopsia?
Lesion of the optic system between optic chiasm and visual cortex.
Where is the lesion for total blindness in one eye?
Lesion of one optic nerve distal to the chiasm
Which pathway includes distinct parallel pathways that originate from different types of ganglion cells?
Retina-LGN-cortex pathway
What is the function of the retina-LGN-cortex pathway?
This parallel processing conveys different types of visual information along each route and underlies reconstructing the visual world and perception.
Which pathway transmits color and shape information for object perception and identification?
Parvocellular
Which pathway transmits movement related information for perception of motion and direction to enable visual attention, alerting, grasping, etc?
Magnocellular pathway
What, separate, pathway transmits some low acuity and color information to primary visual cortex, but mostly projects to extrastriate cortex for visual behavior outside of the usual visual consciousness?
Koniocellular
What are the 2 types of ganglion cells that project information for conscious visual perception?
Parvocellular (P, midget)
Magnocellular (M, parasol)
