L12 - Retina 4 Amacrine Cells Flashcards
What NT do ALL amacrine cells contain? Some also contain?
ALL - GABA or glycine
Some - Ach, DA, ATP, NP
How many types of Amacrine cells are there?
22
Why is it referred to as a BP Dyad synapse?
Referred to as a Dyad because there are 2 elements. In the IPL, all BP contact at least 2 elements - either a GC and amacrine cell or 2 amacrine cells (rod pathway)
In an animal that does not have GABA receptor, the BP response fires smaller or bigger AP?
Fires bigger AP. This shows that amacrine cells fine tunes the “through” response.
Difference between cone and rod BP in relation to whether they synapses onto amacrine cells/GCs or not?
Cone BP synapses with GCs
Rod BP only synapses with two amacrine cells (DOES NOT synapses with GCs)
What receptors are on Rod-BP?
mGluR6 - same as ON BP
40% of all amacrine cells are? They express ____R which releases ____
A2, kainate (iGluR), Glycine as NT - inhibiting the ON and OFF BP it synapses onto
Where is the max vision in rod system?
*It is where A2 amacrine cells are at their highest density
Around 8 degrees
Do BP create directional selectivity?
No - response will be same in either direction light is shone. They only create firing pattern.
What NT do starburst amacrine cells release?
GABA and Ach
What cells are responsible for directional selectivity?
Starburst amacrine cells
Describe the features of a SBAC
1) No axons, only dendrites
2) Only distal part of cell can send outputs out (synapses with directional selective GC)
3) Ca2+ signalling (and hence GABA release) is directional selective - GABA is released when stimulus (light) moves from soma to dendrite but not when the stimulus moves towards the soma
4) Input: Glu, GABA, gly
Output: GABA, Ach
*Directional selectivity is related to GABA release BUT not with Ach (function unknown currently)
T/F: All amacrine cells are crucial for night vision
T
T/F: SBAC are important for motion detection
T
What are the main interneuron in the rod pathway?
A2 amacrine
