Term
| When light goes from scotopic to photopic, what % of rhodopsin is available to catch light? |
|
Definition
|
|
Term
| What cells do the PR's talk to? |
|
Definition
| horizontal cells, bipolar cells, and other PR's |
|
|
Term
| Why are there more than one form of cone channel? |
|
Definition
| Different color channels? |
|
|
Term
|
Definition
the area on the retina in which a stimulus will produce a response from a particular cell.
OR
The area in space that correlates to that area on the retina that produces a response from the cell of interest. |
|
|
Term
| What is an area response curve? |
|
Definition
| The summation of response to stimuli presented in the receptive field |
|
|
Term
| How are PR and bipolar cell area response curves different? |
|
Definition
| both respond to a spot of light, but only the bipolar cell will respond to an annulus of light centered on the receptive field |
|
|
Term
| What is the neurotransmitter for horizontal cells? |
|
Definition
|
|
Term
| How many types of horizontal cells are there, and what is the nomenclature? |
|
Definition
|
|
Term
| What are H1 horizontal cells? |
|
Definition
| receive input from M and L cones under photopic; rods under scotopic. Measures luminosity! |
|
|
Term
| What does not synapse with H1 horizontal cells? |
|
Definition
| S-cones (cyanolabe or 426 nm) |
|
|
Term
| What does the H1 cell control? |
|
Definition
| Which PR to turn off or on, it controls dark and light adaptation |
|
|
Term
| What are H2 horizontal cells? |
|
Definition
| Receive strong input from the S-cones in addition to the M and L cones |
|
|
Term
| What is the ultimate purpose for the H2 cells? |
|
Definition
|
|
Term
| What are the spatial summation fields for horizontal cells? |
|
Definition
| They are circular over 1 arc minute for cones, circular over 10 arc minutes for the rods |
|
|
Term
| What do bipolar cells do? |
|
Definition
| Carry information from the outer plexiform leayer to the inner plexiform layer |
|
|
Term
| What synapses with bipolar cells? |
|
Definition
| PR and horizontal cells on the dendritic side, amacrine and ganglion cells on the axonal side |
|
|
Term
| Do bipolars have their own type of receptive field? |
|
Definition
| yes, they are doughnut shaped known as On- and Off-cells and feature spatial antagonism |
|
|
Term
| What is spatial antagonism? |
|
Definition
| When there is a double receptive field of opposite 'sign' such as an ON center with an OFF surround or vice versa |
|
|
Term
| How many bipolar cells per eye? |
|
Definition
|
|
Term
| How do horizontal cells turn off PR's? |
|
Definition
|
|
Term
| What is the field for an ON cell? |
|
Definition
| Center is ON, annular OFF periphery |
|
|
Term
| What is the field for an OFF cell? |
|
Definition
| center is OFF, annular ON periphery |
|
|
Term
|
Definition
| conventional synapse from the PR --> bipolar cell; only two elements involved. |
|
|
Term
| What is generally stronger for an area response, the center or peripheral response? |
|
Definition
|
|
Term
|
Definition
| the PR forms the pre-synaptic element, but there are multiple (usually three ) post-synaptic elements. The result is PR's can synapse with one horizontal and one bipolar cell at a time. |
|
|
Term
| What are purpose of triead synapses? |
|
Definition
| Allows cross-talk, maintains more efficient neurotransmitter use, sums horizontal cell's message with the PR before it reaches bipolar cells |
|
|
Term
| What do bipolar cells synapse with? |
|
Definition
| sometimes other bipolars and amacrine cells, this is called a backwards flow. Mainly synapses with ganglion cells |
|
|
Term
| What is lateral inhibition? |
|
Definition
| an active process by which adjacent PR's will be managed by a horizontal cell that is deciding which PR's will get to be fire and be 'heard' |
|
|
Term
| What neurotransmitter do On and Off cells use? |
|
Definition
|
|
Term
| What are diffuse vs midget bipolar cells? |
|
Definition
midget are 'broadband' connection, carrying single cones through to the ganglion. For high acuity.
Diffuse bipolar cells have a larger cell body and more extensive dendritic trees --> talk to more than one cone, usually ~6. H1 channel, not H2. |
|
|
Term
| Are rod and cone bipolar channels discrete? |
|
Definition
|
|
Term
| What is lost and what is gained when nerves are unmyelinated? |
|
Definition
| Speed, but what we gain is the possibility for a graded potential |
|
|
Term
| What is the physical location and innervation of an amacrine cell? |
|
Definition
In the inner nuclear layer, synapse in the inner plexiform layer.
Synapses in dyads, on pre and two post synaptic elements |
|
|
Term
| What is a mechanical advantage of having unmyelinated retinal nerves? |
|
Definition
| No myelin to block light transmission and reduce acuity and sensitivity |
|
|
Term
| What do amacrine cell do in frogs? |
|
Definition
| Initiate SkM response to stimuli; small shadow initiates tongue (eating), big shadow initiates legs (flight). Called the photomechanical effect |
|
|
Term
| What do amacrine cells do in humans? |
|
Definition
| reponse do motion, inhibit retina that is viewing a stationary field. Play a role in planning saccades |
|
|
Term
| How many ganglion cells are there per eye? |
|
Definition
| 1.2 million ganglion cells |
|
|
Term
| Ganglion cell AP's are the second in the retinal neuronal cascade after which type of cell? |
|
Definition
|
|
Term
| what are the 5 types of ganglion cells? |
|
Definition
Midget
Parasol
Bistratified
Photosensitive
Other |
|
|
Term
| What is the most populous type of ganglion cells? |
|
Definition
| Midget ganglion cells, about 70% of all ganglion cells |
|
|
Term
| What do midget ganglion cells do? |
|
Definition
| Begin the parvocellular stream: "central vision/what is it" stream. High bandwidth portion of retina. Low # of PR synapses per cell. |
|
|
Term
| Are midget cells slow or fast? |
|
Definition
Slower, can have sustained reponse, poor temporal resolution, longer response.
The retina's 'slow twitch' cells |
|
|
Term
|
Definition
| Magnocellular stream, the 'where' stream. Goes to LGN layer 2. Do not see color, but can see low contrast. |
|
|
Term
| How fast are parasol cells? |
|
Definition
| Relatively fast, not slow. Have better temporal resolution. Can see flicker. More rapid conduction due to larger axons |
|
|
Term
| What are bistratified ganglion cells? |
|
Definition
| Make up 8% of ganglion cells, start the konio stream. Used in blue-yellow color vision |
|
|
Term
| What is a photosensitive ganglion? |
|
Definition
| Has melanopsin photopigment, innervates the superchiasmic nucleus that controls circadian rhythms in pineal gland via melatonin |
|
|
