Term
| The ____ _____ pathway for a signal is photoreceptor to bipolar cell to ganglion cell |
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Definition
| "minimal direct pathway" - shortest pathway |
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Term
| Which two cells form lateral connections and are critical for lateral inhibition and center-surround organization? |
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Definition
| horizontal cells and amacrine cells |
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Term
| rods - make connections to bipolar cells at the ____ _____ |
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Definition
|
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Term
| rods make connection to ganglion cells at the ____ ____ layer |
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Definition
|
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Term
| phototransduction occurs at the ___ segments of the rods |
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Definition
|
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Term
| photoreceptor cell bodies are in the ____ _____ ____ layer |
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Definition
|
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Term
| synaptic termini are in the ____ layers |
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Definition
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Term
| are there more rods or cones in the fovea? |
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Definition
|
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Term
| night vision also know as |
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Definition
|
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Term
| scotopic vision associated with rods or cones? |
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Definition
|
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Term
| photopic vision (daytime, bright) associated with rods or cones? |
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Definition
|
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Term
| color discrimination, fine focus, and rapid motion detection are associated with rods or cones? |
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Definition
|
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Term
daytime vision most associated with (rods/cones)
vision in darker areas more associated with (rods/cones) |
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Definition
daytime - cones
dark - rods |
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Term
| In the dark rods and cones are depolarized. Rods have cyclic GMP gated Na channels. Lots of Na on outside. When you open the Na channels, the rod outer segment is closed, depolarizing the rod. Then rod releases glutamate. So there is a good amount of glutamate released in the dark |
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Definition
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Term
| In the dark rods and cones are (polarized/depolarized) |
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Definition
|
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Term
| Rods have _____ gated Na channels |
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Definition
| cyclic GMP gated Na channels |
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Term
| What happens to the outer segment of the rod when Na channels open? This (polarizes/depolarizes) the rod |
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Definition
| the outer segment closes, depolarizing the rod |
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Term
| rods have discs (in plasma membrane/continuous with plasma membrane) |
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Definition
|
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Term
| cones have discs (in plasma membrane/continuous with plasma membrane) |
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Definition
| continuous with plasma membrane |
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Term
(When light turns on this occurs in the rods)
retinol is originally in 11-cis conformation, and the photon converts it to the All-trans conformation, which activates the enzyme ______ |
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Definition
|
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Term
(In rods)
Transducin transducer light and activates ____, which causes hydrolysis of ____ to ____. |
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Definition
| Transducin activates PDE6, which causes hydrolysis of cGMP to GMP. |
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Term
(In rods)
After hydrolysis of cGMP to GMP, there is nothing to hold the Na channels open, so they close, causing Na to stop flowing into the outer segment. The cell then (depolarizes/hyperpolarizes) and release of the neurotransmitter ______ stops |
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Definition
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Term
| Do rods or cones have quantum sensitivity? |
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Definition
|
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Term
| are rods present in the fovea? |
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Definition
|
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Term
| in the retina, these G-protein coupled receptors absorb photon energy |
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Definition
|
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Term
| There are 3 opsins, blue absorbs ___ wavelengths, green absorbs ___ wavelengths, and red absorbs ____ wavelengths |
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Definition
blue - short wavelengths
green - medium wavelengths
red - long wavelengths |
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Term
T or F
The release of glutamate from rods is an all-or-nothing response |
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Definition
False
The release of glutamate from rods is a graded response. |
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Term
T or F
There are 2 types of postsynaptic bipolar cells |
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Definition
True
One type hyper polarizes when lights are off
One type depolarizes when light is on |
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Term
| what type of glutamate receptor does the hyperpolarizing bipolar cell (OFF cell) express? |
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Definition
|
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Term
| what type of glutamate receptor does the depolarizing bipolar cell (ON CELL) express? |
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Definition
| metabotrophic glutamate receptor |
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Term
what is the rod/bipolar cell synapse called?
what type of bipolar cell do rods synapse with? |
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Definition
spherule
rods synapse with depolarizing bipolar cells |
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Term
| when a rod detects a photon of light, glutamate release (increases/decreases) and the rod bipolar cell is (activated/inactivated) |
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Definition
glutamate release decreases
the rod bipolar cell is activated |
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Term
| horizontal cells near rods have anti-glutamate receptors. When glutamate release decreases the horizontal cells (depolarize/hyperpolarize) while the bipolar cells (depolarize/hyperpolarize) |
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Definition
Glutamate release decreases…
The bipolar cell depolarizes
The horizontal cells hyperpolarize |
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Term
| the rod spherule is what type of synapse (called this because the rod synapses with TWO cells) |
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Definition
diad synpase
The synapse is also a "ribbon synapse" specialized for constant glutamate release ( this term refers to calcium channel positioning and neurotransmitter release which enables rapid neurotransmission signals-wikipedia) |
|
|
Term
| what is the cone/bipolar cell synapse called? |
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Definition
|
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Term
| What type of synapse is the pedicle? (called this because it has 3 elements) |
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Definition
|
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Term
| What are the 3 cells involved in the cone synapses? |
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Definition
Invaginating midget bipolar cell
Flat midget bipolar cell
Horizontal cell |
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Term
| The invaginating midget bipolar cells (depolarize/hyperpolarize) |
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Definition
| depolarize (ON bipolar cells) |
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|
Term
| Flat midget bipolar cells (depolarize/hyperpolarize) |
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Definition
| hyperpolarize (OFF bipolar cells) |
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Term
| In what layer do the rods and cones synapse with bipolar cells? |
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Definition
|
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Term
| Detecting objects lighter than a background is the (on/off) pathway |
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Definition
|
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Term
| Detecting objects darker than a background is the (on/off) pathway |
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Definition
|
|
Term
| which cells detect simultaneous contrast of visual objects? |
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Definition
| horizontal cells - they help enhance edges and contrasts |
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Term
| what are 2 important synaptic interactions that occur at the outer plexiform layer? |
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Definition
1. splitting of the visual signal into two separate channels of information flow, one for detecting objects lighter than background (ON pathway) and one for detecting objects darker that background (OFF pathway)
2. the instillation of pathways to create simultaneous contrast of visual objects |
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Term
| which bipolar cells cells are very small, located in the fovea, and used for detailed vision? |
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Definition
|
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Term
| which bipolar cells are for luminance (how bright or how dim) |
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Definition
|
|
Term
| which bipolar cells respond to red vs. green light? |
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Definition
|
|
Term
| which bipolar cells respond to blue light? |
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Definition
|
|
Term
| humans have how many types of horizontal cells? |
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Definition
|
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Term
| which horizontal cells contact M and L cones primarily but with a small number of contacts to any S cones in the dendritic field |
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Definition
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Term
| which horizontal cells contact short wavelength cones, directing major dendrites to these cones in their dendritic fields where they occur, and contacting with lesser numbers of terminals other types of non-short wavelength cone. |
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Definition
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Term
| Which horizontal cells have large dendritic terminals in medium and long wavelength cones, seemingly avoiding blue short wavelength cones in their dendritic tree |
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Definition
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Term
| What is the retinal area in which changing conditions of illumination produce an alteration of the cellular activity (the area of your world that lands on a certain spot in your retina) |
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Definition
|
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Term
T or F
With receptive fields of bipolar cells & more proximal neurons, the intensity of illumination is relatively unimportant in determining the level of activity… Rather the important parameter is the contrast between the different areas of the receptive field |
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Definition
|
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Term
| amacrine cells lie in which layer of the retina? |
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Definition
|
|
Term
| amacrine cells make contact with what 2 things? |
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Definition
| bipolar cells and ganglion cell dendrites |
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Term
| ___ amacrine cells take the information from rod bipolar cells to cone bipolar cells |
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Definition
|
|
Term
| amacrine cells respond (not release) to what neurotransmitter? |
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Definition
glutamate
they release GABA or glycine, serotonin, Ach, and many others |
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Term
| what are 4 main classes of ganglion cells? |
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Definition
Midget cells
Parasol cells
Bistratified cells
Photosensitive cells |
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Term
| Cone pathway - on center bipolar cells will increase firing rate with light (on/off) center |
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Definition
|
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Term
| Cone pathway - off center bipolar cells firing rate increases with light (on/off) center |
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Definition
|
|
Term
brighter stimuli stimulate (on/off) center cells
darker stimuli stimulate (on/off) center cells |
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Definition
brighter - on
darker - off |
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Term
| turning a light on - In the triad, the bipolar cell will (depolarize/hyperpolarize), horizontal cells will (depolarize/hyperpolarize), and flat off bipolar cells will (depolarize/hyperpolarize) |
|
Definition
Turning a light on - In the triad
bipolar cell - depolarizes
horizontal cells - hyperpolarize, causing flat off cells to hyperpolarize |
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|
Term
T or F
Bipolar cells are specifically involved in lateral inhibition which involves center surround receptive fields aka simultaneous contrast |
|
Definition
False
Horizontal Cells are involved with this |
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|
Term
T or F
If one photoreceptor is hyperpolarized and releases less glutamate, its neighbors will release more glutamate as a result of its surrounding horizontal cell interactions |
|
Definition
|
|
Term
T or F
Every point in the visual field is represented by both ON-center and OFF-center ganglion cells |
|
Definition
|
|
Term
| Every point in the visual field is represented by both ON-center and OFF-center ganglion cells. This enhances the speed of visual processing. Why? it takes MUCH less time to determine that a cell’s firing rate has increased than to detect a decrease! |
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Definition
| It takes MUCH less time to determine that a cell’s firing rate has increased than to detect a decrease |
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Term
| The purpose of having on and off center cells is? |
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Definition
| Detecting edges in a visual field, Transmitting information about firing rates, detect contrast |
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|
Term
In an ON center cell, in which pattern of light would you see the most firing of a ganglion cell?
Uniform darkness
Uniform light
Light only in center
Light only in surround |
|
Definition
|
|
Term
In an OFF center cell, in which pattern of light would you see the most firing of a ganglion cell
Uniform darkness
Uniform light
Light only in center
Light only in surround |
|
Definition
|
|
Term
| In ON bipolar cells, sign inverting feeds onto (ON/OFF) ganglion cells and spiking (increases/diminishes) |
|
Definition
| ON bipolar cells - sign inverting feeds onto ON ganglion cells and spiking increases |
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Term
| In OFF bipolar cells, sign conserving feeds onto (ON/OFF) ganglion cells and spiking (increases/diminishes) |
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Definition
| OFF bipolar cells - sign conserving feeds onto OFF ganglion cells and spiking diminishes |
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|
Term
T or F
The retina is interested in contrast differences (edges, light vs. dark. The on-off pathways are critical to both of these |
|
Definition
|
|
Term
| At what cell does the on-off pathway begin |
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Definition
|
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