The EPSPs from two different synapses occur at the same time and cause a larger depolarization than either one alone can cause. This is an example of:

• A. Presynaptic inhibition.
• B. Postsynaptic melding.
• C. Temporal summation.
• D. Spatial summation.

Answer: (D)

Verified step by step guidance

1. Understand the concept of EPSPs (Excitatory Postsynaptic Potentials): These are changes in the postsynaptic membrane potential that make the neuron more likely to fire an action potential.
2. Recognize that spatial summation occurs when multiple synapses are activated simultaneously, leading to a combined effect on the postsynaptic neuron.
3. Differentiate between spatial and temporal summation: Temporal summation involves multiple EPSPs occurring in quick succession at a single synapse, while spatial summation involves simultaneous EPSPs from different synapses.
4. Identify that the problem describes EPSPs from two different synapses occurring at the same time, which aligns with the definition of spatial summation.
5. Conclude that the larger depolarization caused by simultaneous EPSPs from different synapses is an example of spatial summation, as it involves the integration of signals from multiple locations on the neuron.