Ocular: Phototransduction 2: Nerve Conductance Flashcards
Where are light-evoked (phototranduction) signals transferred onto?
Onto bipolar cells and horizontal cells
What do horizontal cells provide?
Lateral interactions in the OPL
What do bipolar cells do?
Transfer light-evoked signals into the IPL onto the amacrine and ganglion cells
Where do ganglion cells get their signals? Where do they then transmit the signals?
-from bipolar and amacrine cells
-transmit signals to the visual centers of the brain
Is glutamate excitatory or inhibitory?
Excitatory
Examples of glutamatergic neurons:
-photoreceptors
-bipolar cells
-most retinal ganglion cells
Are GABA and glycine excitatory or inhibitory?
Inhibitory
GABAergic and glycynergic neurons:
-horizontal cells
-most amacrine cells
What is the Neurotransmitter for cone pedicles?
Glutamate
Glutamate is _______ in darkness and _________ by light
High, reduced
What happens to the OFF cone bipolar cells and horizontal cells when light hits them?
They are hyperpolarized
What happens to the ON cone bipolar cells when light hits?
They are depolarized by light
Where do OFF cone bipolar cells transfer signals onto?
OFF ganglion cells
Where do ON cone bipolar cells transfer their signals?
Onto ON ganglion cells
What is the midget system?
Where one cone is connected to a midget bipolar cell which is connected to a midget ganglion cell
What is the synaptic terminal of a cone?
Cone pedicle
What is the synaptic terminal of a rod?
Rod spherule
What is the neurotransmitter in rod cells?
Also glutamate
How many types of rod bipolar cells are there? What is the name(s)?
One, ON rod bipolar cells
What happens to the rod bipolar cells when light hits them?
They are depolarized by the light
Hwy si the direct synapse with an A-II amacrine cell important for rod bipolar cell signal?
So the signal can piggyback onto the ON or OFF pathway
Do horizontal cells modulate glutamate release? If yes, how?
Yes, they modulate glutamate release by shorting the activation curves of the rod spherule and cone pedicle Ca channels
Whta do horizontal cells release and what does that inhibit?
GABA, inhibition of bipolar cell dendrites
General light signal transmission pathway:
-light-evoked signals transferred onto bipola and horizontal cells
-horizontal cells provide lateral interactions and feedback to photoreceptors
-bipolar cells transfer the light signals onto amacrine cells (if rods) and ganglion cells (if cones)
-ganglion cells collect signals and transmit to the visual centers in brain
