a. Spatial summation occurs when two excitatory inputs arrive at a postsynaptic neuron simultaneously. Together, they produce greater depolarization.
b. Temporal summation occurs when two excitatory inputs arrive at a postsynaptic neuron in rapid succession. Because the resulting postsynaptic depolarizations overlap in time, they add in stepwise fashion.
c. Facilitation, augmentation, and post-tetanic potentiation occur after tetanic stimulation of the presynaptic neuron. In each of these, depolarization of the postsynaptic neuron is greater than expected because greater than normal amounts of neurotransmitter are released, possibly because of the accumulation of Ca2+ in the presynaptic terminal.
- Long-term potentiation (memory) involves new protein synthesis.
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