Term
|
Definition
| 3 cellular layers, and 2 synaptic layers make up the ______ |
|
|
Term
| epithelial cells lining the retina |
|
Definition
| these cells recycle the photopigments |
|
|
Term
| horizontal cells, synapses between photoreceptor cells and bipolar cells |
|
Definition
| what is found in the outer plexiform layer? |
|
|
Term
synapses between the on/off bipolar cells
and ganglion cells, as well as lateral interneuron(amacrine) cells |
|
Definition
| what is in the inner plexiform layer? |
|
|
Term
1) ganglion cells(parvo/magno)/astrocytes
2) amacrine cells
3) on/off bipolar
4) horizontal cells
5) photoreceptors cells
Muller cells go the whole length |
|
Definition
| list the layers of cells in the retina in the order light would hit them |
|
|
Term
| between photo receptors and bipolar cells |
|
Definition
| where are the glutamtergic synapses? |
|
|
Term
| Lateral geniculate nucleus and super prismatic nucleus? |
|
Definition
| where do the ganglion cells synapse? |
|
|
Term
|
Definition
| lateral/horizontal cells release ____ on rods and cones and on/off bipolar cells |
|
|
Term
GABA or glycine (like the CNS)
they release it onto ON/OFF bipolar cells and ganglion cells |
|
Definition
| amacrine cells release this neurotransmitter in the inner plexiform layer |
|
|
Term
|
Definition
| in general the LATERAL inputs in the retina are _____ |
|
|
Term
|
Definition
| the major excitatory neuron in the eye/brain |
|
|
Term
Muller cell - spans entire retina
astrocytes - in ganglion cells layer |
|
Definition
| name the 2 glial cells of the eye and their location |
|
|
Term
| cones -> bipolar cells -> ganglion cells -> optic nerve -> brain |
|
Definition
| describe the basic retinal circuit (the vertical glutamatergic pathway of the retina) |
|
|
Term
1) phototransduction (light to chemical E)
2) adaption(photo sensitivity)
3) initial feature extraction |
|
Definition
| what are the 3 basic functions of the retina? |
|
|
Term
1) edge detection
2) contrast detection (center surround inhibition)
3) color
4) directional selectivity (detects movement across retina) |
|
Definition
| describe the components of initial feature extraction |
|
|
Term
|
Definition
| main pigment rods use to detects photons of light |
|
|
Term
|
Definition
| general location and # of rods in the retina |
|
|
Term
| multiple rods feed into few ganglion cells |
|
Definition
| rods use convergence, what does this mean? |
|
|
Term
|
Definition
| which cells are more sensitive to light but have low visual acuity? |
|
|
Term
3
red: long wavelength
green: medium wavelength
blue: short wavelength |
|
Definition
| how many types of cones do humans have? name them |
|
|
Term
| they are concentrated in the fovea |
|
Definition
| where are the cones found in the eye? |
|
|
Term
| not really, epecially in the fovea there is a 1:1 ratio between cones and their connection to the optic nerve |
|
Definition
| do cones undergo convergence? |
|
|
Term
|
Definition
| high acuity, low sensitivity cells that function best in bight light(photopic) conditions |
|
|
Term
| no, they are tonically depolarized |
|
Definition
| do photoreceptors have action potentials? |
|
|
Term
in the dark (aka the Dark current)
light inhibits neurotransmitter release but does not STOP neurotransmitter release |
|
Definition
| when do photoreceptors release more neurotransmitter? |
|
|
Term
|
Definition
| dip in the macula of the eye that is concentrated with cones cells that have a 1:1 ration between bipolar cells and ganglion cells, making it an area of high visual acuity(esp the center) |
|
|
Term
1) outer segment: light sensing aparatus
2) inner segment: contains the nuclei
3) synaptic terminal: where synaptic transmitter release occurs |
|
Definition
| describe the 3 parts of a photoreceptor cell |
|
|
Term
discs with rhodopsin, and a membrane with cGMP cation channels
guanylate cyclase converts GMP to cGMP |
|
Definition
| what is found in the outer segment? |
|
|
Term
| cGMP binds to a channel and causes Ca and Na to go down conc gradient(in) to combat the K+ leak in the inner segment and depolarize the cell (remember DARK = depolarized) |
|
Definition
| what does cGMP do in the outer segment of the eye? |
|
|
Term
| a constant K+ leak in the inner segment |
|
Definition
| what keeps a photoreceptors cell relatively depolarized(this happens in light or dark conditions)? |
|
|
Term
| voltage gated calcium channels open giving a coupled excitation event and then membrane bound vesicles are mobilized and diffuse, releasing glutamate |
|
Definition
| when the phororeceptor is depolarized (in the dark) what happens? |
|
|
Term
dark: -40 to -45
light: -60 mV |
|
Definition
| about what mV is a photoreceptor in the dark? in the light? |
|
|
Term
they cause cis-retinal to go to trans retinal -> rhodopsin -> transducin -> activates phosphodiesterase -> cleaves cGMP to 5'GMP,
-decreasing the overall cGMP in the outer segment, closing the Na channels = hyperpolarization because K+ is still leaking out
calcium still enters (not as much-voltage gated channels not activated) and little glutamate release |
|
Definition
| what happens when light hits the outer segment? |
|
|
Term
| on and off bipolar cell pathways |
|
Definition
| what helps you determine contrast? |
|
|
Term
the off layer (closer to the photreceptors) where the off bipolar cells synapse
and the ON layer where the on biplar cells synapse |
|
Definition
| what are the 2 sublamina of the inner plexiform layer and what do they contain? |
|
|
Term
photoreceptors: hyperpolarize with light
On bipolar cells: depolarize(excite) with light
off biplar cells: hyperpolarize with light |
|
Definition
| when light hits a photreceptor, what happens to on bipolar cells in terms of polarization? the photoreceptors? |
|
|
Term
| to sense dark and light stimuli (contrast) |
|
Definition
| what is the purpose of on/off bipolar cells? |
|
|
Term
| mGluR6 (metabotropic glutamate receptors) |
|
Definition
| what is the glutamate receptors on the On bipolar cell? |
|
|
Term
|
Definition
| what is the glutamate receptors on the Off bipolar cell? |
|
|
Term
OFF bipolar has this ion channel,
glu binds & opens channel, and Ca or Na + flow in and depolarize the cell |
|
Definition
| describe the action of the Glutamate receptor the KA/AMPA glutamate receptor |
|
|
Term
this is the on bipolar cell path
g protein coupled 7 transmembrane receptor coupled to a cation channel that closes and hyperpolarizes the cell membrane |
|
Definition
| describe the actions of mGluR6 when stimulated by glutamate |
|
|
Term
| 12, only 1 is exclusively to rods (the rod bipolar cell) so 11 connect exclusively to cones |
|
Definition
| how many types of bipolar cells are there? how many connect exclusively to rods? exclusively to cones? |
|
|
Term
| S cone and Rod bipolar cells |
|
Definition
| short wavelength cone signals use what bipolar cells? |
|
|
Term
|
Definition
| what kind cells to S cone bipolar cells receive input from? |
|
|
Term
|
Definition
| in the fovea what is the photreceptor: bipolar cell: ganglion ratio? |
|
|
Term
| rod cell - rod bipolar cell - A2 amacrine cell - into cone system via gap junctions or to a ganglion cell synapse (using neurotransmitter) |
|
Definition
| how are rod cell signals shunted into the cone system at low light? |
|
|
Term
| rod cell - gap junctions - cone cell (then down the path) |
|
Definition
| at high light levels how do rod pathways get into the cone system? |
|
|
Term
| rod bipolar cells are only ON bipolar cells (they synapse in the ON sublamina) but their signals are shunted through the cone system via A2 amacrine cells |
|
Definition
| there are on/of cone bi polar cells, what do rods have? |
|
|
Term
|
Definition
| ganglion cell system designed to handle tonic, high contrast, fine grain, small area color signals |
|
|
Term
|
Definition
| ganglion cell system designed to handle phasic, (motion) and things over a larger area - not fine detail |
|
|
Term
direct: bipolar cells
indirect: photoreceptor cells (via bipolar) |
|
Definition
| horizontal/lateral cells form direct synapse with ___ and indirect synapses with ___ |
|
|
Term
A type: no axon
B type: with an axon |
|
Definition
| what are the 2 types of horizontal cells? |
|
|
Term
|
Definition
| the somatic region of the horizontal cell has contacts with cones while the ____ end has contacts with rods |
|
|
Term
| A type (no axon terminal to contact the rods) |
|
Definition
| what type of horizontal cell contacts only cones? |
|
|
Term
|
Definition
| what are H1 horizontal cells like? |
|
|
Term
| A type (contact only cones) |
|
Definition
| what are HII & HIII horizontal cells like? |
|
|
Term
they adjust the retina's response to overall level of illumination
- they have a broad receptive field due to extensive gap junctions |
|
Definition
| what do A type horizontal cells do? |
|
|
Term
|
Definition
| inhibitoy feedback from _____ cells to cones and bipolar cells subtracts mean luminance level from signals transmitted to bipolar cells about local luminescence changes |
|
|
Term
|
Definition
| bipolar cell output to ganglion cells are modified by ____ |
|
|
Term
amacrine cells release GABA/glycing and also very specific neurotransmitters (all except seratonin, 5HT) and act more specifically, wheras horizontal cells act more broadly and only do GABA
both are inhibitory |
|
Definition
| what is the difference between horizontal cells besides location |
|
|
Term
|
Definition
| physiological responses of _____ cells are both transient and sustained and they can be depolarized with light (ON cells) in absence of light (OFF cells) or BOTH |
|
|
Term
| 15, M cells and P cells (magno/parvo) |
|
Definition
| how many types of ganglion cells are there? which are most important? |
|
|
Term
edges (of color or light) based on one cell being hyperpolarized or depolarized
segregated signals to the brain allow detection of an edge |
|
Definition
| center surround properties detect what? |
|
|
Term
|
Definition
| helps us to distinguish, recognize and remember real world objects |
|
|
Term
|
Definition
| who first used a prism to separate colors of light suggesting the different colors vibrate different structures in our eye? |
|
|
Term
Young & Hemholtz
there are red, green, and blue receptors and different combinations give different colors |
|
Definition
| who discovered trichromatic theory? what is trichomatic theory |
|
|
Term
he says that color is based on center surround that occurs at the bipolar cell level, and different brain regions that is antagonistic
ex:
red-green
blue-yellow
black-white
(M & L cone system) |
|
Definition
| who came up with opponent process theory? what is opponent process theory? |
|
|
Term
trichrome: in the photoreceptors
opponent process: in the bipolar cells, retinal ganglia cells, and lateral geniculate nucleus (high brain centers) |
|
Definition
| where does trichromatic color theory occur anatomically? opponent process theory? |
|
|
Term
| the presence of 3 pigments in cone cells (S, M, L cones aka blue 437, green 533, red 564 nm) |
|
Definition
| what is the physiological basis of trichrome theory? |
|
|
Term
|
Definition
| where is the peak sensitivity of rod cells? |
|
|
Term
|
Definition
| each photo-receptors has an opsin, what is this similar to? |
|
|
Term
|
Definition
| if there is a defect in an opsin, then what happens to the ability to sense a specific color? |
|
|
Term
| chromosome 7, M & L found on the X chromosome, so most color vision defects are x linked recessive, and thus sex linked |
|
Definition
| where is the S cone(blue) pigment found genetically? the M & L cones? |
|
|
Term
|
Definition
| how similar are S opsin to M & L opsins? to rods? |
|
|
Term
|
Definition
| how similar is the M opsin to the L opsin? |
|
|
Term
| makes it hard to distinguish colors based on their blue content,, ex: blue & gray or red and purple |
|
Definition
| as people age, yellowing and darkening of the lens makes blue darker, what problem does this cause? |
|
|
Term
digoxin: yellow/green are indistinguishable
viagra: blue
organic solvents: have color changes |
|
Definition
| what color does digoxin make your vision? viagra? what else messes up your colors? |
|
|
Term
glaucoma: 20-40% are normal, but others vary
diabetes: s cones
macular degeneration: red/green (M& L cones in fovea)
Optic neuritis
Parkinsons
Stroke
Trauma |
|
Definition
| list diseases that cause color deficits and how |
|
|
Term
ishihara pseudo-isochromatic plates
-hard to distinguish dichromats from anomalous trichromats (protanopia from protanomaly) |
|
Definition
| most common color vision test, what is a draw back of this test? |
|
|
Term
| anomaloscope: adjusts color bandwidths to fish out color defects |
|
Definition
| what helps identify genetic defects in the opsins? |
|
|
Term
| AMD (age related macular degeneration) |
|
Definition
| this disease is common in people over age 50 where there is a loss of central vision & acuity due to permanant degeneration of photoreceptors |
|
|
Term
wet: vascularized form, get excessive blood vessel growth that causes photoreceptor death
dry: unknown genetic cause that causes soft drusen formation under the macula (and throughout the retina) destroying photoreceptors |
|
Definition
| what is the difference between wet and dry macular degeneration? |
|
|
Term
|
Definition
|
|
Term
it can only stop the progression of the disease, not reverse it, but they use a laser to stop the blood vessel growth
in the past did macular translocation to move the macula out of the damage area by moving the retina, but the brain has to be re-taught how to see |
|
Definition
| what is the treatment for AMD? |
|
|
Term
|
Definition
| a group of genetic disease that causes loss of rod photoreceptors and loss of night vision |
|
|
Term
| RP (retinitis pigmentosa) |
|
Definition
| normally there is a thick layer of photoreceptors, but in ___ only one layer remains |
|
|
Term
relies on documentation:
1) progressive loss in photoreceptor function by ERG
2) visual field testing
3) genetic testing |
|
Definition
|
|
Term
|
Definition
| in addition to having only 1 layer of photoreceptors, ____ patients have a very jumbled, disorganized retina |
|
|
Term
|
Definition
| this disease targets all sensory cells (photoreceptors, hair cells etc) so it cause hearing loss, but acts like RP in that people end up blind and/or lose night vision |
|
|
Term
|
Definition
| what is the treatment for Usher syndrome? |
|
|
Term
| usually ganglia cells are affected, so the stem cells have to find their way all the way back to the brain |
|
Definition
| what is the problem with stem cells to treat RP? |
|
|
Term
1) prosthetics
2) algae transplant channel things
3) stem cells |
|
Definition
| what are some other new tratement options for RP? |
|
|
Term
|
Definition
| disease of ganglion cells, happens when the optic nerve is damaged and the nerve fibers degenerate, causing blind spots, and loss of PERIPHERAL vision |
|
|
Term
| aqueous humor doesn't properly drain to the trabecular meshwork (eye aqueous humor drainage system) causing pressure on the optic nerve and thus damage to it |
|
Definition
| describe the anatomical cause of glaucoma |
|
|
Term
most common: open angle glaucoma
less common: closed angle glaucoma |
|
Definition
| what is the most common form of glaucoma? what is the other type that is less common but more urgent? |
|
|
Term
1) increased eye pressure because the trabecular mesh work is less effective at draining, don't see symptoms until there is vision loss
2) closed angle has a structural problem: the iris breaks down, patients have pain, and surgery can be done to repair it, but it can also be caused by surgery, this type is detected early on |
|
Definition
| what is the different between open angle and closed angle glaucoma? |
|
|
Term
| use drugs to control the outflow of aqueous humor: adrenergic drugs |
|
Definition
| what is the treatment of glaucoma? |
|
|
Term
| it detects a voltage difference between the cornea and a reference location in response to a flash of light (like an EKG) |
|
Definition
| what does the ERG do? what is it? |
|
|
Term
|
Definition
| part of the ERG usually a downward negative deflection at the onset of light: the activation of photo receptors (glutamate decrease) |
|
|
Term
|
Definition
| starts at trough of the a wave measures transmission of the photoreceptor cells to the ON bipolar cells, maginitude of this determines of there is a defect in this pathway, tied to K+ and muller cell function |
|
|
Term
|
Definition
| this wave on an ERG is due to RPE(retinoid pigmented epithelial) cells, not an important gauge in looking at function |
|
|
Term
|
Definition
| this wave on the ERG looks at the OFF bipolar cell response (potential that occurs when you shut the light off) |
|
|
Term
| rods (cones cant detect flicker) |
|
Definition
| what does a flicker ERG look at? |
|
|
Term
| RETINAL, brain can still be messed up |
|
Definition
| ERG's measure ___ function, so a person with a normal ERG can still have vision problems |
|
|
Term
2: nasal portion- contralateral
temporal portion- ipsalateral |
|
Definition
| how many hemiretinas does each retina have? name them |
|
|
Term
| the right hemiretina (left nasal and right temporal) |
|
Definition
| which hemi retina of each eye sees the left visual field? |
|
|
Term
|
Definition
| the middle portion of your vision that gets information from both eyes |
|
|
Term
inferior retina
signals go to V1 in the calcarine cortex(superior bank takes info for superior retina inf. for inderior rerina) |
|
Definition
| what makes up the superior visual field? where do these signals go? |
|
|
Term
retina
optic nerve
optic chiasm
optic tract
lateral geniculate nucleus(thalmus)
optic radiations
primary visual cortex (V1) |
|
Definition
| follow the vision pathway from the retina to the brain |
|
|
Term
| 6, from dorsal -> ventral 6,5,4,3,2,1 |
|
Definition
| how many layers does the LGN have and how are they arranged? |
|
|
Term
|
Definition
| Receptive fields and center-surround properties are processed here |
|
|
Term
| 2,3,5 from the ipsalateral eye |
|
Definition
| what layers of the LGN process input from each eye (monocular stuff)? |
|
|
Term
| layers 1 & 2 (so rods only, motion and movement) |
|
Definition
| what layers of the LGN are parallel channels and the magnocellular system handled? |
|
|
Term
| layers 3-6 (they are small cells) do color and form info |
|
Definition
| what layers of the LGN handles the parvocellular system? |
|
|
Term
| optic chiasm (lose half of vision on both sides-nasal side) |
|
Definition
where is the lesion if there is bitermporal hemianopsia
blineness in nasal hemiretina of each eye
NO PERIPERHAL vision |
|
|
Term
| optic tract (lose nasal and temporal of 1 eye) |
|
Definition
where is the lesion if there is homonymous hemianopsia &
blindness in the contralateral visual field |
|
|
Term
|
Definition
|
|
Term
| V1/V2 nerve or cortical damage |
|
Definition
what sort of damage can cause
scotoma (blob in front of eye)
complete blindness, or
blind sight (perception issue) cannot see, but can precieve motion/activity |
|
|
Term
V3-form and dynamic form
V4-color
V5-motion
IT-object recognition
PP-object location and navigation |
|
Definition
| what do V3, V4, V5, IT, and PP detect? |
|
|
Term
|
Definition
what lesion would cause:
blindness in ipsalateral eye
monocular vision
deficits in depth perception and stereopsis |
|
|
Term
|
Definition
| most visual processing occurs in what lobe? |
|
|
Term
|
Definition
|
|
