The process that integrates neural inputs to a post-receptor cell is called what?

• A. Spatial summation
• B. Temporal summation
• C. Lateral inhibition
• D. Adaptation

Answer: (A)

When a neuron collects signals from several inputs, those signals produce postsynaptic potentials at different places on the dendritic tree and soma. The neuron then adds these potentials as they converge toward the axon hillock to decide whether to fire. This combining of inputs from multiple spatial locations is called spatial summation. If inputs arrive rapidly from the same site, the neuron can also sum them over time—temporal summation—which is a related but distinct way the cell integrates signals. Lateral inhibition would shape sensory contrast by inhibiting neighboring pathways, and adaptation refers to a receptor’s diminished response with a sustained stimulus. In this question, the integration across different locations on the postsynaptic cell is the key idea, so spatial summation is the best fit.