Summation - Nervous System

SUMMATION

As already mentioned, each neuron can have many synapses. Therefore, the potential changes that occur in it depend on the net effect of all synapses. Certain synapses may produce inhibitory effects and others may produce stimulatory effects. What happens in the postsynaptic neuron depends on which effect is predominant.

For example, if action potentials arrive rapidly in a synapse that has a stimulatory effect, the potential in the postsynaptic neuron may reach threshold quickly and produce an action potential. At the same time, if action potentials arrive in a synapse that produces an inhibitory effect, the postsynaptic membrane will be-come hyperpolarized, making it difficult for action potential to be generated. This mechanism of inte-grating the effects of two or more neurons by the postsynaptic neuron is known as summation.