When several inhibitory postsynaptic potentials (IPSPs) arrive at the axon hillock rapidly in sequence from a single dendritic location, hyperpolarizing the postsynaptic cell more and more and thus preventing an action potential, this is an example of
A) temporal summation.
B) spatial summation.
C) a normal action potential.
D) an action potential with an abnormally high peak of depolarization.

Question

Quizplus · Accepted Answer

Temporal summation occurs when several presynaptic inputs arrive in rapid succession at the same synapse, leading to the summation of their effects on the postsynaptic neuron. In the case described, the IPSPs arriving from a single dendritic location are adding up over time, hyperpolarizing the membrane potential and preventing the generation of an action potential. This is an example of temporal summation, rather than spatial summation (which involves the summation of inputs from multiple synapses at different locations). The other choices are not applicable to the scenario described.

When Several Inhibitory Postsynaptic Potentials (IPSPs) Arrive at the Axon