Flashcards in RGCs and Amacrines (M2) Deck (43):
What type of neurotransmitter does AI amacrine cells release? 1. What are these cells involved in? 2
2. lateral inhibition
What are the visual symptoms that a patient with multiple sclerosis can present with?
1. dec VA
2. reduction in visual fields
3. sudden-onset diplopia
4. pupillary defects
5. color vision defects
6. Uhthoff's sign
7. Pulfrich's stereo phenomenon
Where do starburst amacrines with cell bodies in the GCL stratify in?
Is the synapse from AII amacrine cells onto ON cone bipolar cells sign-conserving or -inverting? 1. What is the connection like? 2
2. gap junctions
How many different types of amacrine cells are there?
What is the process of action potentials jumping node to node to increase speed called?
How many midget bipolar cells are connected to a foveal midget RGC? 1. What does this setup gear the vision towards? 2
2. high spatial resolution
Where are the voltage-gated sodium channels located that lead to saltatory propagation?
Nodes of Ranvier
For midget RGCs what is the relative cell body size? 1. Dendrites branching? 2. Stratification type? 3. Percent of total RGCs? 4
3. ON or OFF sublamina of IPL
Do midget or parsol RGCs exhibit center-surround antagonism?
What is the ratio of amacrine:bipolar synapses for parasol RGCs? 1. Midget RGCs? 2
What do AI amacrine cells have roles in?
1. amplifying rod-mediated signals
2. mediating the receptive field surround in RGCs during scotopic conditions (light more apparent)
What is the dendritic spread amount for small amacrine cells? 1. Medium? 2. Wide-field? 3
1. less than 300 um
2. between 300 and 500 um
3. greater than 500 um
What percentage of the foveal RGCs are midget? 1. Periphery RGCs? 2
For parasol RGCs what is the relative cell body size? 1. Dendrites branching? 2. Stratification type? 3. Percent of total RGCs? 4
3. ON or OFF sublamina of IPL
Do amacrine cells have graded potentials or action potentials?
Do midget or parasol RGCs have a more sustained response to light onset or offset? 1. Which have more transient response? 2
1. midget RGC
2. parasol RGC
Where are amacrine cells located?
2. GCL ("displaced" amacrine cells)
How do rod bipolars connect with RGCs?
no direct synaptic connections. Piggy-back into cone system via AII amacrines and onto their bipolars
Do parasol or midget RGCs receive input from more cones?
Do parasol RGCs display convergence or divergence along the path of a signal? 1. What does this lead to? 2
2. greater spatial summation than midget RGCs
Why are action potentials needed in retinal ganglion cells?
graded potentials decay gradually with distance from the point of initiation
What type of neurotransmitter do wide-field amacrine cells usually use? 1. What do mono-stratified wide-field amacrines mediate? 2
2. lateral inhibition (for center-surround)
What are the major functions of amacrine cells?
1. provide feedback inhibition to bipolar cells
2. provide feedforward inhibition to RGCs
3. visual processing
What are the dopaminergic amacrine cells that can send a process up into the OPL called?
Where do starburst amacrines with cell bodies in the INL stratify in?
During the daytime, what neurotransmitter is released more frequently? 1. What does this do to AII amacrine cells? 2.
2. closes gap junctions between AII amacrines and cone ON bipolars (preventing ON bipolar saturation)
What type of amacrine cells are involved in rod-driven retinal circuitry?
What is so unique about the dendrites of amacrine cells?
they can be presynaptic and postsynaptic
What do OFF parasol RGCs receive input from? 1. ON parasol RGCs? 2
1. multiple diffuse flat bipolars
2. multiple diffuse bipolars (not sure if flat or invaginating)
How many rod bipolar cells do AI amacrine cells receive input from? 1. Where do they provide output? 2
2. to same bipolar cells (negative feedback loop)
What is the Pulfrich Effect due to?
difference in conduction velocity between the right and left optic nerves
For bistratified RGCs what is the relative cell body size? 1. Dendrites branching? 2. Stratification type? 3. Percent of total RGCs? 4
3. ON and OFF sublamina of IPL
What type of neurotransmitter do narrow-field amacrine cells usually use? 1. How many sublamina of the IPL do each of these stratify in? 2. What do these types of cells mediate? 3
2. 2 or more
3. vertical inhibition
What neurotransmitters do starburst amacrine cells contain?
What are the three most common RGCs?
3. small-bistratified RGCs
Do starburst amacrine cells have a sustained or transient response? 1. Do they have center-surround (and ON or OFF)? 2. What are their circuits mostly involved in? 3
2. yes (both ON and OFF)
3. motion detection
What is the inhibition done by amacrine cells thought to contribute to?
1. inhibitory surrounds of RGC receptive fields (enhance center-surround)
2. make RGC responses to light stimuli more transient
For dopaminergic amacrine cells, what causes that cells to release dopamine?
1. light stimulation
2. circadian rhythm (high during day)
What is the most frequent cause of demyelination in the CNS? 1. What are the first symptoms these patients usually have? 2
1. multiple sclerosis
2. visual deficiencies
Is the synapse from AII amacrine cells onto OFF cone bipolar cells sign-conserving or -inverting? 1. What is the connection like? 2
2. glycine release (hyperpolarize)
What does the closing of AII amacrine cell gap junctions by dopamine lead to in the IPL?
1. switch from scotopic to photopic vision
2. alters gain of retinal circuits