The phenomenon which decides whether an action potential will be generated or not based on the cumulative effect of various excitatory and inhibitory signals that act on the neuron is called summation.
Summation is of two types- temporal and spatial.
When multiple presynaptic cells are acting o a neuron then the phenomenon of spatial summation occurs.
The spatial summation leads to the addition of various signals acting at different places of the neurons, i.e there is the addition of signals occurring at various areas of input.
If the signals are excitatory they will add up and would contribute to the generation fo action potential and if they are inhibitory they would try to suppress the firing of action potential
