where does summation occur
Temporal summation is the linear addition of graded potentials that overlap in time; that is, a second potential arrives before the first one from that source has finished. Spatial summation occurs when there is simultaneous arrival of graded potentials originating from more than one synaptic input. Summation occurs at the trigger zone. Typically a multipolar neuron has many active synapses at a given time, with multiple potentials being produced at each.