1. Everyone gets Ca2+!: Calcium is required for both long term potentiation (LTP
ID: 207810 • Letter: 1
Question
1. Everyone gets Ca2+!: Calcium is required for both long term potentiation (LTP) and long term depression (LTD). How is it possible that an influx of calcium ions into a post synaptic cell does not activate both LTP and LTD pathways? Describe the differences between the LTP and LTD mechanisms in Schaffer collateral-CA1 synapses and how calcium plays a key role in different ways. Be specific as to the different key molecules involved.
2. Synaptic Input: Neuron A receives excitatory inputs from neurons B and C. The excitation from neuron B arrives at the same time as that of neuron C. Do these excitatory components sum linearly? Why or why not? Sketch what the summed inputs would look like, and sketch what the actual synaptic input looks like. How do active conductances affect this summation? (NMDA or gated channels).
Explanation / Answer
1. It is possible that an influx of calcium ions into a post synaptic cell does not activate both LTP and LTD pathways because it is now well established that rises in postsynaptic calcium are ideal for triggering long term depression pathway, however ample sturdier activation of N-methyl-d-aspartate further, that lead to more increases in postsynaptic calcium are essential to trigger long term potentiation pathways. LTP is due to stimulation of CaMKII that phosphorylates target proteins. Whereas LTD, consequence from stimulation of Ca2+-dependent.
Long-term potentiation present at Schaffer collateral synapses of synaptic strength is mainly due to the changes in AMPA receptor number and AMPA biophysical properties. Increase concentration of calcium, activate the SK2 channels that may contribute in synaptic changes once an activity-dependent decline contributes to long term potentiation.
LTD like LTP, govern the efficacy of transmission at the Schaeffer collateral synapse, but LTD, decline the effectiveness of synapses in the cerebellum as well as hippocampus.Calcium ion concentration, increase the efficiency of LTD.
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