When summation results from buildup of neurotransmitter released simultaneously by several presynaptic end bulbs it is called?

When summation results from the buildup of neurotransmitters released simultaneously by several presynaptic end bulbs, it is called spatial summation. This process occurs when multiple synapses on a postsynaptic neuron are activated at the same time, leading to a greater cumulative effect on the neuron's membrane potential. Spatial summation can enhance the likelihood of reaching the threshold for action potential generation.