What is spatial summation in neurons? Spatial summation occurs when a number of axons synapse on a single neuron. Spatial summation occurs when synaptic potentials summate over a short interval of time. Spatial summation occurs when synaptic potentials that originate in different locations summate within a single neuron. Spatial summation occurs when one neuron can make synapses with a number of different neurons through collateral branches of the axon.