Type of summation that occurs when a number of subthreshold stimuli from same axon are repeated

Type of summation that occurs when a number of subthreshold stimuli from same axon are repeated

• A. Temporal summation
• B. Spatial summation
• C. Positive feedback
• D. Negative feedback

Answer: (A)

Temporal summation occurs when a number of subthreshold stimuli from the same axon repeat in rapid succession, causing their postsynaptic potentials to overlap in time. Each stimulus evokes an excitatory postsynaptic potential that, by itself, doesn’t reach threshold. If the next EPSP arrives before the previous one has fully decayed, their voltages add together, increasing the overall depolarization. If enough stimuli occur quickly enough, the cumulative depolarization can reach threshold and trigger an action potential. If inputs came from different neurons at the same time, that would be spatial summation; positive or negative feedback refer to network or system regulation rather than this temporal integration.

Temporal summation occurs when a number of subthreshold stimuli from the same axon repeat in rapid succession, causing their postsynaptic potentials to overlap in time. Each stimulus evokes an excitatory postsynaptic potential that, by itself, doesn’t reach threshold. If the next EPSP arrives before the previous one has fully decayed, their voltages add together, increasing the overall depolarization. If enough stimuli occur quickly enough, the cumulative depolarization can reach threshold and trigger an action potential. If inputs came from different neurons at the same time, that would be spatial summation; positive or negative feedback refer to network or system regulation rather than this temporal integration.