9. Neuro-optho Flashcards
(24 cards)
ON-center system: Light is shined in the middle with darkness in the surround
Higher rate of firing
ON-center system: Light is shined in the surround with darkness in the middle
Low rate of firing
ON-center system: Darkness in the surround and center
Medium rate of firing
ON-center system: Light in the surround and center
Medium rate of firing
OFF-center system: Light is shined in the middle with darkness in the surround
Low rate of firing
OFF-center system: Light is shined in the surround with darkness in the middle
High rate of firing
OFF-center system: Darkness in the surround and center
Medium rate of firing
OFF-center system: Light in the surround and center
Medium rate of firing
FACT: Major changes in firing rates of the ON and OFF center occur in the edges
FACT: Major changes in firing rates of the ON and OFF center occur in the edges
Scotopic vision
Allows you to see in starlight
Photopic vision
Allows you to see in bright light
Mesopic vision
Allows you to see in dim light (moonlight) (combo scotopic and photopic)
Which adaptation process takes longer: dark adaptation or light adaptation?
Dark adaptation takes longer (20-30mins) because you need to replenish all photopigments
Visual pathway
Optic nerve –> optic chiasm –> optic tract –> synapses with: 1. Lateral geniculate nucleus –> optic radiations or Meyer’s loop –> primary visual cortex 2. Suprachiasmatic nucleus –> wakefullness/sleep (circadian rhythm) 3. Superior colliculus –> coordinated eye movements 4. E-W nucleus –> pupillary reflex
A right side up person appears how in the retina?
Upside down and flipped right-to-left
Importance of visual information to cross over at center
Allows for depth perception
Which region of the retina accounts for a disproportionate cross-sectional area of the optic nerve, tract, radiations, and cortex?
Foveal region
What is the Meyer’s loop? What specific information does it carry?
Meyer’s loop is optic radiation fibers that curve anteriorly first before going posteriorly. Carry lower retinal fibers that carry upper visual field information
What happens if you have a lesion in the RIGHT Meyer’s loop?
Can’t see left upper visual field (left quadrant)
Scotoma
Partial alteration in field of vision
Where would this lesion be?
Homonomyous hemianopia
Left optic tract (contralateral homonomyous hemianopia)
Where would this lesion be?
Bitemporal hemianopia
Optic chiasm
Heteronymous hemianopia
Where would this lesion be?
Right Meyer’s loop
